# Xduoo Amplifiers



## JoeDoe

After a quick search, the only threads available regarding Xduoo are concerned with its portable amps.
  
 Just found these two on eBay.
  
 http://www.ebay.com/itm/xDuoo-TA-01-Tube-24bit-192KHz-USB-DAC-HiFi-Headphone-Amplifier-/290976915350?pt=LH_DefaultDomain_0&hash=item43bf935f96
  
 http://www.ebay.com/itm/xDuoo-TA-02-Tube-HiFi-Headphone-Amplifier-/290977485903?pt=LH_DefaultDomain_0&hash=item43bf9c144f
  
 TA-01 looks similar in function to the Aune T1 (however, the Xduoo supports 192k!) while the TA-02 seems LD Mk 1+ ish. 
  
 Has anyone had the opportunity to check these guys out?


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## JoeDoe

Bump


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## JoeDoe

And one more for fleeting hope...


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## Dopaminer

Ba-ba-bump.
  
 I just found the TA-02 on Amazon.jp here in Japan, for the same price as the Ebay seller.  It`s only a hundred bucks, so I may just go for it.  The TA-01 looks even more interesting; I could only find one review in English and it was luke warm, but very poorly written...
  
 http://earmass.com/2013/07/23/xduoo-ta-01-entry-level-tube-dacamp-combo/
  
The TA-01 I can`t find in Japan, but it`s still crazy-cheap from Ebay.  I`m using the Continental V2 from ALO with HD800 and love it but am interested in trying other portable tube options.  May just go for Analogue-squared Paper.....


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## JoeDoe

That's basically what I've seen. Keep us posted!


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## grizzlybeast

2.1 watts into 32 ohms is pretty powerful...


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## diaBoliQu3

This is a warm, thick, nice body, wide sound stage, and detail. Just finish doing side by side comparison with Aune T1. Thinking of getting rid my Aune T1.


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## grizzlybeast

diaboliqu3 said:


> This is a warm, thick, nice body, wide sound stage, and detail. Just finish doing side by side comparison with Aune T1. Thinking of getting rid my Aune T1.


 
 seriously?
  
 can you go into a bit more depth as to why? and explain the comparison results?


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## tattoou2

If anyone is interested, I believe RTW HiFiHouse stocks these.  I think RTW is in Chicago.


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## Rayzilla

I saw one of these yesterday at Jaben, Hong Kong. The guy said that they are on the warm side.


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## tattoou2

I bought a TA-01 to simply test.  Unfortunately, it does not seem to be compatible under Win8.  I cannot install drivers in two Win8 laptops and I get a message that it is incompatible with my system.


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## jason1969

Think they use a WM usb chip... try a Linux Distro, try a spare 2.5" HD with Linux or old copy of windows?
  
 Microsoft is sort of like IBM PS/2 only in slow motion re backwards compatibility & hardware... sigh.


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## tattoou2

jason1969 said:


> Think they use a WM usb chip... try a Linux Distro, try a spare 2.5" HD with Linux or old copy of windows?
> 
> Microsoft is sort of like IBM PS/2 only in slow motion re backwards compatibility & hardware... sigh.


 
 Tested it with a Win7 laptop and it worked fine.  Very warm, somewhat thick-sounding with decent sound stage.  Good power.  I used a DT880 250 ohms. Returned it; just not my cup of tea.


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## jason1969

Noted, this is where you end up as the Aune - only going through more components re valves, op-amps, capacitors, diodes etc as applicable. Reports elsewhere indicate the volume pot is not a top brand, and the supplied valve "poor".
  
 The GOOD thing about the Aune is it offers a starting point from which people have already improved - components to valves. At this rate we might actually create a Head-Fi DAC-AMP - kit or assembled  Commercially it might be a winner and people can even select parts based on their chosen headphone charateristics and preferences.


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## jason1969

Did you try a Mullard/Brimar valve?
  
 Stock china valve.
 Absolute junk - does improve to garbage after about 2hrs.
 So warm it is unusable, mid & vocals aren't great either, sort of a nasty mucked up 50s radio.
  
 NOS Brimar valve.
 Shockingly better - out of the box, and should get better over next 2hrs.
 Slightly warm, but not thick. Bass is deep, controlled. Vocals are airy, highs far better.
  
 Adele's vocals on quieter tracks sound absolutely haunting.
 However this is an amp that does not like extremely complicated music, musical fidelity headphone DAC amp (HPA) was better in that respect - BUT could become tiring quite quickly.
  
 There are 2 Gain jumpers.
 Stock is both set to HIGH not Low, so I may try setting them to Low at some point.
  
 Might also nosey around the PSU caps as that is an easy. Not sure about this one, NOS Mullard/Brimar makes it auditionable, stock tube is a toilet.


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## Maxx134

I am curious about this and the similar priced, new "Hifi RACOON SG300".
Old Thread here:
 http://www.head-fi.org/t/550692/impression-ber-muzik-tiny-tube-dac/0_20


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## Sniper1

Wow; check out this nice xDuoo TA-03 (or sometimes referred to as XT-03 )...
 Anybody tried it ?
  
http://www.xduoo.com/xduoo/ProductShow.asp?id=41


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## ostewart

I just got the TA-02, might try and get the TA-03 once ive review the TA-02.
 Stock i found the TA-02 underwhelming, lots of power but quite hot up top, little body, sucked out mids. Also one of the chinese tubes failed on me, lost it's vacuum (white mist at the bottom of the tube), so i got a pair of Mullard's off ebay (1964, mitcham factory) and this amp is tons better.
  
 I love the look of it, the build is good, the pot is nice and smooth and the sound is lush and smooth as is expected of tubes, no more sucked out mids like the stock tube. The mullard may not have the best top end, but pair it with slighty brighter headphones and it is great. With the new tubes, I am very happy with it. A great buy if you have extra tubes lying around or if you buy some different tubes pretty much straight away.
  
 Pics sooon


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## ostewart

Pictures:


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## kramer5150

Some pics of the internals... looks neat and tidy.  No first hand experience though.


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## ostewart

I left the top tube protectors off of mine, looks better


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## JoeDoe

Bump in case anyone has pulled the trigger on this guy!
  
 http://www.ebay.com/itm/xDuoo-xt-3-tube-headphone-amplifier-USB-DAC-24Bit-192KHz-2014-export-verision-/141225587675?pt=US_Home_Audio_Amplifiers_Preamps&hash=item20e1b373db


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## Maxx134

joedoe said:


> Bump in case anyone has pulled the trigger on this guy!
> 
> http://www.ebay.com/itm/xDuoo-xt-3-tube-headphone-amplifier-USB-DAC-24Bit-192KHz-2014-export-verision-/141225587675?pt=US_Home_Audio_Amplifiers_Preamps&hash=item20e1b373db






While it looks excellent, it does not state output impedance which, based on its design, should be higher since it is a transformer-less tube output.
Not sure if it has an impedance selector. Seems like slightly below the little dot 3 I used to own, but the little dot 3 had no DAC so this could be a sweet solution.


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## JoeDoe

Forgive my ignorance as this stuff has always evaded me, but is adapter impedance and output impedance the same?


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## Maxx134

You only worry about output impedance if you have headphones or IEMs that are low impedance because the ideal ratio is ten to one, with the amp output impedance being ten times less than the headphones impedance.
So the sound is better. 
OTL amps (output transformer less) naturally have a higher output impedance, so they sound better with headphones of higher impedance.
They may still sound OK, but low impedance headphones and IEMs can pick up him and noise floor more easily, so you would need better amp.
Transistor/op amp based amps don't have these problems as they can have very low impedance.
So my suggestion would be to go for a hybrid tube amp which uses solid state for output,
OR
If you can afford the best, a tube with transformer out is probably best if you like tube sound...
The only drawback with these designs are the expense of the output transformers and the lower power output which some cans like the Hifiman HE6 need a lot..
So to sum up.
This amp is nice for a higher impedance cans in the range that the specs actually state, in its power output Specs they state the usable impedance and that would be the ideal range.


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## JoeDoe

maxx134 said:


> You only worry about output impedance if you have headphones or IEMs that are low impedance because the ideal ratio is ten to one, with the amp output impedance being ten times less than the headphones impedance.
> So the sound is better.
> OTL amps (output transformer less) naturally have a higher output impedance, so they sound better with headphones of higher impedance.
> They may still sound OK, but low impedance headphones and IEMs can pick up him and noise floor more easily, so you would need better amp.
> ...


 
 Wow. I actually understood most of that. Thanks maxx. Since I'm mostly a Grado guy, looks like I'll hang on to my LD1 instead of letting upgraditis get the best of me...


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## Hanzo

joedoe said:


> Wow. I actually understood most of that. Thanks maxx. Since I'm mostly a Grado guy, looks like I'll hang on to my LD1 instead of letting upgraditis get the best of me...


 
 +1 Nicely explained.  I love learning stuff from this forum thanks to well worded, thoughtful explanations.
  
 Thanks!


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## NyquistRate

grizzlybeast said:


> seriously?
> 
> can you go into a bit more depth as to why? and explain the comparison results?


 
 Ooh, please provide more detail.  The Aune T1 is too bright for me, even after rolling tubes to several Amperex and others.


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## Superdud

Guys ,
  
 Just got a TA-03 locally in Australia from A1Futureshop  . They are the distributor for Australia and New Zealand. 
 Haven't got a chance to test it out yet. Do you reckon they will drive the Senn HD700 ? .


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## Nhubley

Should be able to drive the HD700.


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## ges11t

superdud said:


> Guys ,
> 
> Just got a TA-03 locally in Australia from A1Futureshop  . They are the distributor for Australia and New Zealand.
> Haven't got a chance to test it out yet. Do you reckon they will drive the Senn HD700 ? .


 
 Hey, I'm in Australia as well. Would love to hear your opinion on the TA-03, especially with the HD700 as I've got the HD800 and looking for a nice sounding tube amp.


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## kablecorner

Glad you asked. I first was thinking of either Schiit Audio or Woo Audio. However after discovering the TA-03 is much less in price and has a built in dac I gave it a go.
  
 The built quality:
 Very impressed.  Much much better then those Little Dot and Dark Voice/La Figaro amps.  Nice solid built with smooth side panels and has gold plated rca terminals. The packaging was great too. xDuoo spent some effort on the packaging to make it look professional unlike La Figaro was terrible. Instruction manual was clear and precise written in english.  Comes with a usb and AU type power cable. 
  
 The sound:
 At first the TA-03 sounded bit thin and bright. After about 10 hours burn in it started sounding more like a $300+ amp.  Through the HD700 to be honest , surprisingly I was very impressive. Lots of details in the music, Brightness disappeared, bass got tighter and cleaner, midrange silky smooth ,it now sounded more like a tube amp. I compared it with my Matrix M-Stage HPA-2 USB and immediately I could hear the differences. Especially when listening to classical music ( violin and piano music) the TA-03 definitely has this warmness in the music compared to the Matrix.
  
 Overall xDuoo did a great job on their top end model tube amp. Price is reasonable and well built. For the price paid I don't really complaints.


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## CriticalTodd

I picked up the TA-01 through the Massdrop deal and just today lugged it to my office cube to power my JVC HA-S680s (Brainwavz replacement pads). I also swapped out the stock tube with a Tung-Sol. I haven't messed with the gain jumpers. I find, for my uneducated ears, that I like the sound so far. I haven't burned them in much yet nor done any A/B testing but, at first blush, I'm happy with them. I'll try to remember to post an update once I've put a few days listening through them.


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## czcsfb

My TA-03's getting REALLY hot after 15 mins listening, by meaning hot I meant the whole body of my TA-03, not only the tubes (I know they are getting hot in all tube amp cases). Anybody has same issue? Is mine in right condition? Does this high temperature hurt the amp? Thanks in advance.


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## spykez

Going to bump this thread, my parents, especially my pops LOVES music and they just got done listening to my Little Dot MKIII and they LOVED the sound. So I'm planning on getting them some ampage going for their office.
  
 I'm kind of looking for an amp/dac in one, at some point I want to connect another amp that can power passive speakers.
  
 I'm confused with this TA-03. On the back it shows "Line In" on the RCA ports, but yet on their website, it shows at the bottom it can connect to other devices using the line out...check box 3 for details.
  
 http://www.xduoo.com/xduoo/EnProductShow.asp?ID=41
  

  
 So..do those ports actually do both input and output or what's the deal with this?


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## czcsfb

Good to know, I used my TA-03 as a pure amp and didn't expect my TA-03 could line out like the picture suggests. Anyway, I just tested it as a DAC connecting to my laptop and it did line out through the same ports successfully, so the result is positive, you are right the ports do input when used as a pure amp and output when used as a DAC like xDuoo suggested. Though I prefer the sound when it works as a amp pairing with my other DACs. Really like my TA-03. 
  
 If you like the sound of Little Dot's, then you won't be disappointed with TA-03. The only problem I can say is that my TA-03 has got overheated on surface and sides (not only the tubes) after 20-30 mins listening, I still couldn't find if it's my unit‘s issue or a common phenomenon for all xDuoo products. BTW, there is no functional problems on my unit, just got too hot to touch on its surface during listening.


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## kablecorner

Yes,when USB socket is used, the line in socket can be as output to an amp .


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## spykez

haha thanks guys, the site was down with some error so I asked xDuoo myself. I've NEVER gotten an answer back from ANY company so quick. It was like, within 20 minutes of sending the email they got back to me!
  
@czcsfb
  
 Could always get one of these 
 http://www.walmart.com/ip/4-Mini-Personal-Fan-Silver/34136727
  
 I got one for my mom as a joke, it's been running for years and actually pushes a lot of air haha. She keeps it on her desk. Out of stock online but there's always a shelf full at the stores.


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## czcsfb

Haha, I got ur idea. Well, I will keep using my TA-03 more to see how things going. Plus, ur feedback from xDuoo really seems help, Im gonna ask them directly If mine is safe. Anyway, thank u for all the information provided here.


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## spykez

here the email. Their site can be a bit weird
  
service@xduoo.com


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## rseminario

I'm planing to buy a ta-03, but dont seem to find many reviews, can you you guys help me with this? How does it compare to darkvoice 336, a bottlehead crack, woo audio (apart from the fact that it has a dac).


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## spykez

I can tell you now woo audio is in a different league, and a lot pricier


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## cleg

Made small video about TA-02

[VIDEO]https://www.youtube.com/watch?v=9BvEY6wwk6M[/VIDEO]


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## BCHIFI

Hi.. I'm looking for a tube amp, I don't need a DAC.. so, which would be better the xduoo TA-02 or TA-03?


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## nmatheis

Saw the TA-01 is up on MassDrop for $135 shipped. Thinking about using it mostly as an amp (Fiio X5 -> TA-01 -> AKG K553, HiFiMan HE400, and SoundMagic HP200). Good fit? Good deal?


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## alicaria

bchifi said:


> Hi.. I'm looking for a tube amp, I don't need a DAC.. so, which would be better the xduoo TA-02 or TA-03?



Ta02 can be beter for you
03 more professional


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## NeObliviscaris

Can anyone recommend this as a desktop Amp/DAC: https://www.massdrop.com/buy/xduoo-ta-01-dac-amp


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## alicaria

neobliviscaris said:


> Can anyone recommend this as a desktop Amp/DAC: https://www.massdrop.com/buy/xduoo-ta-01-dac-amp




Yes it's very good for this price


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## Me7roiD

Hey guys,
  
 Headfi newb here - and, as you could imagine, I'm scouting for some good entry-to-mid-level equipment which will mostly be used with my closed-back Denons and Senn HD650s (all kinds of rock / blues / jazz / funk). For budget, convenience & purely audio reasons, I'm interested in getting an integrated DAC + amp unit - both are an absolute necessity so I'd rather have them combined in one piece. I have looked at Schiit's combos and, while they seem like a good idea even though most of them are separate units, Julius' review @ Headfonia.com somewhat surprisingly seemed to favour the Aune T1 over the Schiit entry-level combo. Based on numerous comments within the HeadFi community and elsewhere, I'm left with the impression that Xduoo's TA-1 seems to represent an improvement over the Aune T1; Chinese-made equipment seems to be held in high regard lately and has been included in numerous of the "best" lists available around here - so I'm assuming that, in general, Xduoo make nice equipment (for the price).
  
 Now, my real question is how you guys feel about Xduoo's TA-3 DAC + amp:
http://www.xduoo.com/xduoo/EnProductShow.asp?id=41
 Weirdly enough, it has been dropped over on Massdrop at least once over the last few months and yet, I can't seem to find any full-length reviews of the TA-3. Luckily, some of you seem to have experience with it (thanks for sharing it in this thread!) - but some more detail would be very much appreciated... Generally, I'm wondering whether the TA-3 does represent a real improvement over the TA-1, as well as whether the "hotness" issue is something to worry about in the long run.
  
 Alternatively, I've also looked at JDS Labs' O2+ODAC combo which, with the 6.3mm jack "option" included, would end up costing quite a bit more though - and that's even before VAT. Besides, their new "Element" looks like a more interesting and better proposition in terms of design and sound quality - but it comes at a cost of >100 USD more than the Xduoo TA-3 which I must admit I find more handsome than the Element. Yeah, yeah, I know, glowing tubes and newbs - I admit that the added value of tube rolling is a really exciting option... aside from the purely aesthetic side of things 
  
 So it'd be nice if any one of you has the knowledge to help me out here - both with the above questions and with a general pointer in the direction of Xduoo / JDS / Schiit / elsewhere. I would, of course, just snatch a TA-3 and write a review - but to be honest my untrained ear doesn't really have that much to compare it to (yet!).


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## alicaria

this is turkish review of xduoo ta-01
 http://www.kulaklik.web.tr/xduoo-ta-01-lambali-dacamp-incelemesi/


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## Me7roiD

Thanks... The product I was really interested in hearing about was the TA-3, though. I can find bits and bobs on the TA-1 on various sites, but no comparisons / detailed reports on the TA-3 whatsoever.
  
 Bottom line is, I'm not so sure if that's the 'right' product since there's nowhere I can see actual numbers based on the TA-3's performance which I could pit against other similar usb tube dac amps. Considering how prices on the Xduoo TA-3 have mysteriously been jacked up by at least 20% from September 1 universally - which I found rather annoying - I'm already reconsidering.


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## elliotpiano

tattoou2 said:


> Tested it with a Win7 laptop and it worked fine.  Very warm, somewhat thick-sounding with decent sound stage.  Good power.  I used a DT880 250 ohms. Returned it; just not my cup of tea.


 
 Would you say that this amp doesn't sound good with high impedance headphones? Should I go with the Aune T1 if I have HD580's?


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## plainbriny

Got mine (TA-01) today.
  
 So far I like it, some have complained about the Chinese tube, but I found it OK.
 Since 17AU7s are not over priced here, I might try some other tubes in the next couple weeks.
 But I think I will use the stock tube for some time, to see how it performs after run-in.


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## plainbriny

jason1969 said:


> ... There are 2 Gain jumpers.
> Stock is both set to HIGH not Low, so I may try setting them to Low at some point.
> ...


 
  
 I have asked Xduoo, and they told me, just leave them at high, saying that the sound at high is better than low.


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## plainbriny

My tube rolling journey has started for a couple days by now...
  
 I have replaced the stock tube (12au7 China) with a Toshiba 5814A. Actually at first I intended to purchase plain Toshiba 12au7 Hi-S for communication and testing, but the seller mistakenly sent me a 5814A. Turned out I am the lucky one. Compared to the stock tube, the sound is more smooth and full. At first I found the Chinese tube OK, but after several days with 5814A, I put the stock tube back and found it not as pleasant as 5814A. Perhaps I have damaged the tube during the removal/reinstall process, because the mica is cracked and I can hear some noise, which was not present before the tube rolling and with 5814A.
  
 I have also bought a gold lion ECC82/B749, I think it is a reissued tube since the box is new and the price is very reasonable. I found that 5814A is not inferior to Gold Lion, but the burn in time for 5814A is much longer than Gold Lion, so the comparison may not be fair.
  
 From the same seller of 5814A, I also got one Toshiba 5963. Someone on the net have considered that 5963 very close to ECC802S, I can't comment on this, since I don't have experience with ECC802S, and only put the 5963 on for a very short time. However, my first impression of 5963 is also very good. The highs of 5814A are more piercing than 5863, sometimes a bit uncomfortable, while 5963 is more spacious than 5814A. However, the image I got from 5814A is clearer than 5963, and the mids seem richer. Which is better, I can't decide yet. Update: I have to admit, I can't really tell the difference of the two so far. 
  
 BTW, the 5814A I got are triple mica version, which is said to increase the ruggedness and reduce the microphonics. And indeed I didn't experience any microphonics with it. Interestingly enough, the stock 12au7 china also has triple mica structure, while the 5963 I got and gold lion 12au7 have double mica structure.
  

  
  
 Since these Japanese tubes are not as well known as those European/US ones, the prices are very reasonable and I am really happy with them, for now.


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## plainbriny

Both 5814A and 5963 are both very good on xDuoo TA-01, but I still want to try something different.
 So here it is, Sylvania 12BH7A in place of 12AU7:
  

  
 I have asked xDuoo and they clearly stated that 12BH7 can be used in place of 12AU7, that's reassuring.
 However, as the weather gets hotter, so as the temperature of TA-01, though it still functions well...
  
 This is a grey oval-plate, D-getter 12BH7A with yellow Sylvania marks (almost invisible now).
 I can't tell the difference between Toshiba 5814A and Toshiba 5963, but the upgrade to 12bh7a had significantly improved the dynamics, sound stage, warmth and speed.
 Some have argued that 12au7 is more emotional than 12bh7, however, I found the opposite. Maybe these Japanese tubes are more neutral?
 Next I would like to try 6350, however, I can't find an adapter for it now...


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## harry501501

plainbriny said:


> Both 5814A and 5963 are both very good on xDuoo TA-01, but I still want to try something different.
> So here it is, Sylvania 12BH7A in place of 12AU7:
> 
> 
> ...


 
 Hi, I've no experience with tube amps and was wondering if they would power my hd650s? I have the Xduoo X3 DAP which is excellent and far better than any of the Fiio DAPs I've used.


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## plainbriny

I don't have HD650, thus can't give you a definite answer.
 However, TA-01 is very powerful and can drive 16-600 ohm headphones.
 Of course, how does it pair with HD650 is another question.
 Since you already have DAP, maybe you can use their pure amp TA-02, or some popular tube amp, such as Bravo V2.
 (on the Bravo Audio V2 thread, some claimed that Barvo Audio V2 does not pair well with HD650 or high impedance headphones.)


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## plainbriny

Sylvania 6350 (green label, black plate, D(?)-getter) on TA-01 through a custom 6350 to 12au7 adapter.
  

  
 Only power on for a few hours now...
 Haven't compared with 12BH7A thoroughly, but so far it's not inferior to 12BH7A.


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## RedJohn456

got the TA-03 yesterday and I am in heaven   So damn good I was actually surprised lol. Can't wait for the tubes to settle and eventually tube roll. But for now, ut sounds like boss sauce out of my Geek Out V2. The amp is clearly the star here, the dac seems so so.


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## Alan Torres

jason1969 said:


> There are 2 Gain jumpers.
> Stock is both set to HIGH not Low, so I may try setting them to Low at some point.


 
 Noob here, I've opened the xduoo ta-01 and I see the gain jumpers but I have no idea how to actually switch/change it. Pls help


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## plainbriny

1. Open the cover by unscrew the top four screws (two in the front, two in the back).
  
 2. On the PCB near the back side (near the USB and RCA connectors), you can see two jumpers: J7 and J8. The two jumpers are placed in HIGH position by default. 
  

  
 3. There are four combinations for two jumpers, however, according to the production description, there are THREE levels of gain. Thus I assume you can set three levels as follows: a) both J7 and J8 set to HIGH (default), b) either J7 and J8 set to HIGH, and the other set to LOW (medium level), and c) both J7 and J8 set to LOW.
 Update: this part is wrong. There are only TWO levels, HIGH and LOW. J7 and J8 each serves one channel, J7 for left and J8 for right.
  
 However, I have asked xDuoo, and they told me that the sound quality of high gain is better than low gain.
  
 Therefore, if it's not absolutely necessary (such as high sensitivity/low impedance headphones), you should just keep the default HIGH gain setting.


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## Alan Torres

I guess I'll just leave it as is then. Thanks for the info


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## plainbriny

Today I read the thread on high gain/low gain (http://www.head-fi.org/t/543242/q-high-gain-low-gain-quality-difference) and decide to try it out.
  
 Turned out my post regarding the high gain/low gain setting for TA-01 was wrong: There was only TWO levels, not three. Therefore JP7/JP8 serve for each channel. If you set it to HIGH/LOW or LOW/HIGH, you will notice the volume difference between left and right. I believe JP7 is for left and JP8 is for right.
  
 Back to the high gain/low gain setting, I heard from Xduoo that sound quality of high gain is better. But their "sound quality" might not what we mean, rather it might just refers to "power/loudness". Ever since I got TA-01, I used HIGH gain setting, today I changed it to LOW, and it's not that bad. Actually I thought I heard more details and dynamic ranges with low gain, as well as more open stage.
 However, since I can't do a side-by-side comparison, this is really subjective and might just be some psychological effect.
  
 Anyway, if your cans did not come with high impedance, low gain might not be a bad idea after all. Just try it out and stick with the setting that suits you best.


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## Joel Eckert

The TA-01 is extraordinarily harsh. Tons of power, but ....
  
 I'll be replacing the tube with a Gold Lion and will update with the results.


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## plainbriny

Perhaps you can try the low gain setting as well.
  
 Since my headphones all have relative low impedance, I prefer the low gain setting over the high gain, though the guys in xDuoo claim high gain will provide "better quality". 
  
 Also you could try 12BH7 or 6350 (with adapter), both should perform better than any 12AU7 (even gold lion).


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## plainbriny

A small complaint to TA-01:
  
 The blue power LED of my TA-01 started to flickering a couple of weeks ago, and finally totally dimmed.
  
 I opened the case the find that the led is powered with 30V from the DC converter, with a 220K resistor in between to lower the voltage to around 2.5V. I have suspected the problems in the LED, the resistor, but they are all good.
  
 Finally I cut out the trace, using the 12 V from the power switch, and converted to 2.5V with a cheap DC converter module to power the LED, and now every thing works well. I don't know whether this is related to the use of 12BH7/6350 or not, but if you have doubt, there are many good 12AU7 equivalent tubes (I prefer 5814A over the others, though 6350 is still my favorite).


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## caenlenfromOCN

Does anyone know where I can download the drivers for the TA-01 model? I googled but nothing is popping up... I need it for Windows 10 because it is not showing up...


----------



## Joel Eckert

I can make the drivers available, have them on my Google Drive, not sure if it will let me post links to files though, let me know.


----------



## caenlenfromOCN

joel eckert said:


> I can make the drivers available, have them on my Google Drive, not sure if it will let me post links to files though, let me know.


 
  
 Yes please that would be very helpful, I am surprised there is a not a link for a website to just download them though


----------



## Joel Eckert

I can't seem to find it, had problems with my Windows user profile and had to blow it away.
  
 http://www.xduoo.com/xduoo/En/DownList.Asp
  
 Assuming it is xmos-usb-drive-xxx
 either of those files


----------



## caenlenfromOCN

joel eckert said:


> I can't seem to find it, had problems with my Windows user profile and had to blow it away.
> 
> http://www.xduoo.com/xduoo/En/DownList.Asp
> 
> ...


 
  
 Thanks I downloaded the XMOS 3.0 version, not sure why they would have a 2.0 as well... but oh well. Yeah I will be using the USB on the TA-01.  Thanks again and take care ^^


----------



## caenlenfromOCN

EDIT:  I got it installed, you have to login to the website XMOS, create an account, then download the drivers that way.
  
 I actually prefer the sound on this to my Vali 2... was not expecting that to happen...
  
 DOES ANYONE KNOW, HOW TO REMOVE THE TUBE????  agh its driving me insane, I have been slipping my fingers on the top of the tube for 30 minutes, I got a golden lion and I can't even get stock out to put new one in... lol


----------



## plainbriny

You have to unscrew the top two screws in the front, and the top two screws in the back.
 Then you can lift the top cover and replace the tube.
 If you use taller tube, like 12bh7, it's possible to replace the tube without opening the cover, but I haven't tried that though.


----------



## caenlenfromOCN

plainbriny said:


> You have to unscrew the top two screws in the front, and the top two screws in the back.
> Then you can lift the top cover and replace the tube.
> If you use taller tube, like 12bh7, it's possible to replace the tube without opening the cover, but I haven't tried that though.


 
  
  
 Do you know if the xduoo ta-01 can roll a 6922 tube? I have some 6922 NOS I want to use... but I am not sure its compatible and don't want to risk frying it.


----------



## plainbriny

caenlenfromocn said:


> Do you know if the xduoo ta-01 can roll a 6922 tube? I have some 6922 NOS I want to use... but I am not sure its compatible and don't want to risk frying it.


 
  
 Direct drop in is not likely.. the pins are different.
 You need at least an adapter to convert the pins, but even so I am not sure whether the circuit will be compatible.


----------



## caenlenfromOCN

plainbriny said:


> Direct drop in is not likely.. the pins are different.
> You need at least an adapter to convert the pins, but even so I am not sure whether the circuit will be compatible.


 
  
 I have them side by side and the spacing of the pins is exact same... hmm :/


----------



## plainbriny

pin number and spacing are the same, but the spec are different.
  
 12au7:
 1: plate 2
 2: grid 2
 3: cathode 2
 4: heater (+)
 5: heater (+)
 6: plate 1
 7: grid 1
 8: cathode 1
 9: heater center-tap (ground)
  
 6922:
 1: plate 2
 2: grid 2
 3: cathode 2
 4: heater (ground)
 5: heater (+)
 6: plate 1
 7: grid 1
 8: cathode 1
 9: internal shield (N)
  
 pin 4 and pin 9 are different.
  
 Also, heater voltage for 12AU7 is 12V (series) or 6V (parallel), while 6922 is 6.3V.
  
 I am not sure whether it will work. I know there's adapter to use 12AU7 in place of 6922, because 12AU7 can use 6.3 V designed for 6922. But I don't know whether the reverse is possible, since the circuit might provide 12V or 6V, and it will depend on the circuit design. An adapter might work (6V parallel) or might not work (12V series).


----------



## caenlenfromOCN

plainbriny said:


> pin number and spacing are the same, but the spec are different.
> 
> 12au7:
> 1: plate 2
> ...


 
 I see, noted, thanks! ^^


----------



## rikk009

I see there is a balanced amp from Xduoo http://www.xduoo.com/xduoo/En/ProductView.Asp?ID=14 but nowhere I can find it's price or a review.


----------



## Holypal

The new balanced tube amp finally arrived, in black or red color.

https://www.aliexpress.com/store/pr...-Headphone-amplifier/2718009_32827387939.html


----------



## rikk009

Holypal said:


> The new balanced tube amp finally arrived, in black or red color.
> 
> https://www.aliexpress.com/store/pr...-Headphone-amplifier/2718009_32827387939.html


By arrived you mean you bought it? Would like to hear impressions, that price is tempting and red colour is unique indeed.


----------



## Heops (Aug 26, 2017)

Anyone know anything about the sound and quality of the XDUOO TA-20?


----------



## chillysalsa

The new TA-20 looks interesting, anyone have more details on the architecture/design or sound?

I've had the TA-3 for several months now and can say for higher impedance cans it is fantastic. However, it definitely needed a 12AU7 replacement to sound it's best. I put a Japanese Baldwin (mullard design) tube and it's amazing with HD800. The warmth and more up front presentation is a great compliment to balance out the cool and wide balance of the cans, I'm blown away for the price.

Did try to change the 6P19 tubes, those are interesting. After buying about 10 on eBay, I could only find about 3 that were not micro phonic. However, the two Russian brands available sounded pretty much the same, and the stock Chinese tubes were pretty quiet anyway. The tube is a outstanding choice for an OTL amp, with a plate resistance Rp of about 100 ohms it's perfect for 300 to 600 ohm cans. I measured the output into 300 ohms and it managed 20V peak to peak, so that's some 2W into the HD800, which is double the allowed maximum. I'm listening to most stuff at 9 to 11 o clock on the volume knob. By 12 is starting to get uncomfortable and at 2o clock it takes your breath away (not listening volumes). Needless to say it drives them effortlessly!


----------



## Heops

There are images of almost everything including the components on the aliexpress site:
https://www.aliexpress.com/store/pr...-Headphone-amplifier/2718009_32827387939.html


----------



## RedJohn456

chillysalsa said:


> The new TA-20 looks interesting, anyone have more details on the architecture/design or sound?
> 
> I've had the TA-3 for several months now and can say for higher impedance cans it is fantastic. However, it definitely needed a 12AU7 replacement to sound it's best. I put a Japanese Baldwin (mullard design) tube and it's amazing with HD800. The warmth and more up front presentation is a great compliment to balance out the cool and wide balance of the cans, I'm blown away for the price.
> 
> Did try to change the 6P19 tubes, those are interesting. After buying about 10 on eBay, I could only find about 3 that were not micro phonic. However, the two Russian brands available sounded pretty much the same, and the stock Chinese tubes were pretty quiet anyway. The tube is a outstanding choice for an OTL amp, with a plate resistance Rp of about 100 ohms it's perfect for 300 to 600 ohm cans. I measured the output into 300 ohms and it managed 20V peak to peak, so that's some 2W into the HD800, which is double the allowed maximum. I'm listening to most stuff at 9 to 11 o clock on the volume knob. By 12 is starting to get uncomfortable and at 2o clock it takes your breath away (not listening volumes). Needless to say it drives them effortlessly!



On the subject of TA03, I personally like the stock tubes as they provide a really clear and pristine sound, which matches well with my HD600 and AKG K7XX. But I did try the bottlehead tubes and I liked the change in sound, so I may think of tube rolling again in the future. 

I am getting the TA20 in for review and will post impressions and make a thread for it once I have it in my hand   From what I understand, it is supposed to be a noticeable step up but I will withold personal judgement till I heard it for myself. I plan on using it with the balanced out of the Aune S6.


----------



## RedJohn456

Oh lookie who showed up to the party   

Haven't had a chance to play around with it but I will be sure to post impressions and comparisons properly once I have some playtime with it!


----------



## chillysalsa

Nice, looks good. What is the range for the digital volume control?


----------



## RedJohn456

chillysalsa said:


> Nice, looks good. What is the range for the digital volume control?



Goes to a maximum of 95 and the wheel keep scrolling, if that makes sense.


----------



## chillysalsa

Yea so it's and encoder connected to a solid state antenuator.


----------



## chris.egeskov

I like the idea of a balanced tube-amp - it could be fun to try it out


----------



## chillysalsa

[QUOTE="RedJohn456, post: 13695364, member:
Haven't had a chance to post around with it but I will be sure to post impressions and comparisons properly once I have some playtime with it![/QUOTE]
Any chance to play some impressions/comparisons to the TA-03?


----------



## Joong

Holypal said:


> The new balanced tube amp finally arrived, in black or red color.
> 
> https://www.aliexpress.com/store/pr...-Headphone-amplifier/2718009_32827387939.html


Can you share your experience with the XDUOO-TA-20?
My th900 phones should be tamed in highs, and the amp might be economic solution.
Many people who believe in Chi-fi should be interested for sure.


----------



## xenithon

Very much intrigued. Been looking for a tube amp to experiment with - with my ZMF's and HD800's. Had my eye on the LD Mk6+ as I wanted balanced but it is more than double the price of the TA-20. Keen to here some impressions on this amp.


----------



## omegaorgun (Apr 28, 2018)

RedJohn456 said:


> Oh lookie who showed up to the party
> 
> Haven't had a chance to play around with it but I will be sure to post impressions and comparisons properly once I have some playtime with it!



I just got the TA-01 and really impressed so ordered a Genalex tube for it. How are these DAC's and if your ever parting ways with one let me know.

The TA-01 packs serious punch and drives the T50RP with ease and is very loud at 12 o'clock.


----------



## caenlenfromOCN

omegaorgun said:


> I just got the TA-01 and really impressed so ordered a Genalex tube for it. How are these DAC's and if your ever parting ways with one let me know.
> 
> The TA-01 packs serious punch and drives the T50RP with ease and is very loud at 12 o'clock.



loudness is different than being properly drived. are you getting nice bass slam?


----------



## omegaorgun (May 1, 2018)

caenlenfromOCN said:


> loudness is different than being properly drived. are you getting nice bass slam?



Yep it has a full and satisfying sound, I have a Genalex Gold Lion tube ordered for it. Tested a cheap JJ which was nice but defective so returned that.

EDIT: JJ was not defective some weird setting in windows was messing up the sound.


----------



## omegaorgun

Threw a Gold Lion in the TA-01 and it is very sweet indeed. Musical gravy .


----------



## RedJohn456

omegaorgun said:


> I just got the TA-01 and really impressed so ordered a Genalex tube for it. How are these DAC's and if your ever parting ways with one let me know.
> 
> The TA-01 packs serious punch and drives the T50RP with ease and is very loud at 12 o'clock.



Its only the TA-03 that has a dac, and it's not bad as far as all in one solutions go, but I mainly use it as a standalone amp. The TA03 has lots of power on tap


----------



## omegaorgun

So just got an NFB.11 and the TA-10 is comparably as loud with a T50RP, it's more powerful than a NFB in low gain but maybe 80-85% when it's in high gain. So it's loud and the SQ is also comparable. 

You get something as good as an NFB with XLR & Tubes, I was selling mine but may keep it.


----------



## vlach

RedJohn456 said:


> Oh lookie who showed up to the party
> 
> Haven't had a chance to play around with it but I will be sure to post impressions and comparisons properly once I have some playtime with it!



Well? Are you going to share your impressions of the TA-20?


----------



## smallcaps

Sorry to necro this thread, but I am thinking of grabbing the TA-20 and online impressions seem to be very sparse. Anyone have any experience with this model? Thanks for any info you can afford!


----------



## omegaorgun

smallcaps said:


> Sorry to necro this thread, but I am thinking of grabbing the TA-20 and online impressions seem to be very sparse. Anyone have any experience with this model? Thanks for any info you can afford!



Don't be sorry at all, these are awesome devices.

What DAC are you pairing it with? I have the TA-10 which uses the AK4490 and responds well to tube change. They have the same power output it can get a T50RP to adequately loud levels and will shake them near the top. I love the SQ on mine is as good as NFB.11 etc but again depending on the tube smoother, more 3D as the imaging is great.
I don't know how different the two tubes will be but if you have the right DAC it should be great, let me know how it is if you get it.
I was going to sell mine a while back but opted not as it's rare and well sounds amazing! Paired with my MDR-Z7 it's truly amazeballs!

Note: I also have the smaller TA-01 which is a pocket rocket but I do not like how xDuoo have not released an updated spec page for the newer version.


----------



## smallcaps

omegaorgun said:


> Don't be sorry at all, these are awesome devices.
> 
> What DAC are you pairing it with? I have the TA-10 which uses the AK4490 and responds well to tube change. They have the same power output it can get a T50RP to adequately loud levels and will shake them near the top. I love the SQ on mine is as good as NFB.11 etc but again depending on the tube smoother, more 3D as the imaging is great.
> I don't know how different the two tubes will be but if you have the right DAC it should be great, let me know how it is if you get it.
> ...


Hi @omegaorgun and thanks for your reply and sharing your experiences. Still shopping for a dac to pair with the TA-20... most likely something like the SU-8 or another delta/sigma dac. I guess I will make the plunge regardless of the little discussion around this product. Will share once I get a hold of it. cheers


----------



## omegaorgun

smallcaps said:


> Hi @omegaorgun and thanks for your reply and sharing your experiences. Still shopping for a dac to pair with the TA-20... most likely something like the SU-8 or another delta/sigma dac. I guess I will make the plunge regardless of the little discussion around this product. Will share once I get a hold of it. cheers



I will of course recommend the TA-10.


----------



## grig

any feedbacks on the TA-20 ?


----------



## smallcaps

grig said:


> any feedbacks on the TA-20 ?


I've been using it for about a month now. Currently fed by an SMSL SU-8 in balanced mode, driving Beyerdynamic T1.2 via the balanced XLR.

So far, it's been really good and I'm able to push the T1.2s adequately. Compared to my Cavalli Liquid Spark, it actually sounds much more neutral with the stock tubes burned in, whereas the LS has a lower-mid hump, making it sound warmer some how. Differences in dynamics and resolution are moot, however the TA-20 has wider and deeper stage. 

Didn't really understand how an amp could be 'holographic', but the TA-20 does sound more 3D compared to the LS. Maybe it's the depth and instrument seperation? As for speed, it's not noticeably slower, but maybe the T1.2s mask this, as they are fairly fast cans to begin with.

I'm really looking forward to tube rolling at some point, and I haven't pushed any planars with it yet, but overall I'm really happy with the TA-20. Not only does it sound really good, but it's pretty compact, has decent connectivity, is built fairly well and the price is quite reasonable. The fact that it's balanced end to end is a bonus.


----------



## Brooklyn70

How well will this play with Planar cans,     What’s it sound like??


----------



## Brooklyn70

How well does the t20 play with planar headphones??


----------



## smallcaps

Brooklyn70 said:


> How well does the t20 play with planar headphones??


They work fine with the HE4XX I had before I sold them. It's a hybrid amp and the amp section is SS, so should work fine with most planars. There isn't exactly tons of power on tap with the TA-20 tho. However for the price, it's a pretty versatile amp and it compliments the rest of my collection very well.


----------



## arielext

Ta-20 VS loxjie P20 anyone?


----------



## arielext

I'll do the comparison myself  Just added the Xduoo TA-20 to my set-up.
Initial impression: they feel to have more soundstage as compared to the loxjie p20


----------



## arielext

Noise levels are higher compared to P20 but overall sound quality I'm giving that to the TA-20.
The detail retrieval is amazing combined with high end headphones like the TH900 and Stellia.
The TA-20 offers a wide soundstage and good placement. The synergy of Stellia with tube amps remains something that is breath taking.


----------



## omegaorgun

Do you guys ever notice a little click here and there when cycling through media on the PC like spotify and YouTube etc?


----------



## S Crowther

FireLion said:


> Do you guys ever notice a little click here and there when cycling through media on the PC like spotify and YouTube etc?


Anyone do tube rolling with the TA-20. I'm presently using Amperex Bugleboys.


----------



## omegaorgun

S Crowther said:


> Anyone do tube rolling with the TA-20. I'm presently using Amperex Bugleboys.



Always wanted a bugle boy supposed to be very good.


----------



## Ultrainferno

Today we look at the Xduoo HK TA-20 tube headphone amp. A first look, now on Headfonia!

https://www.headfonia.com/xduoo-ta-20-picture-sunday/

Of course we'll have a full review soon


----------



## S Crowther

FireLion said:


> Always wanted a bugle boy supposed to be very good.


Easy to find on eBay. Sounds good but I have not tried enough of others to say.


----------



## omegaorgun

Ultrainferno said:


> Today we look at the Xduoo HK TA-20 tube headphone amp. A first look, now on Headfonia!
> 
> https://www.headfonia.com/xduoo-ta-20-picture-sunday/
> 
> Of course we'll have a full review soon



Cool the TA-10 that is also a nice all in one. It's worth spending some money on a couple of NOS tubes, you can get them cheap enough on eBay and there is a heap of 12AU7's. 12AX7 adds a little gain.

I find the old tubes to be pretty amazing in the TA-10.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/163783700293

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/162615323290


----------



## dB Cooper (Sep 3, 2019)

FireLion said:


> It's worth spending some money on a couple of NOS tubes, you can get them cheap enough on eBay and there is a heap of 12AU7's. 12AX7 adds a little gain.



Finding that getting a little bit of gain would help since I have to climb up into the 70 range to listen to music at volume. Completely new to tubes but this seemed like the bargain of the century. It's built like an 1980s Mercedes Benz. The LED volume display is way too bright but that is the only complaint I could throw at it. I don't have much to compare it to, was using an O2 amp with a Burson v5i OP amp and was happy but you know, the audio itch. So after getting a pair of planars I wanted to "push" them and this amp kept coming up here and there with great reviews from everyone that talked about it. For the price it's a powerhouse.  They definitely add stage to an already pretty wide stage presence M1060 and my HD58X benefited as well.  You gotta go balanced in though, so to get this I had to fork money on a DAC; Gheshelli Labs ENOG2, cables and of course the tubes. No point getting this if you're not going to play with your tubes.  Currently using some 1960s Sylvania tubes made for Baldiwn organs, they sound good. Next on deck is a pair of GEs from the same era.

Only 2 watts but for 32 Ohm planars that's plenty of power.  Totally enjoying detail I'd never heard in my music before, glad I got here without spending too much on other stuff... man Hi-Fi was expensive then and it's expensive now. My wallet hates the internet.


----------



## omegaorgun

dB Cooper said:


> Finding that getting a little bit of gain would help since I have to climb up into the 70 range to listen to music at volume. Completely new to tubes but this seemed like the bargain of the century. It's built like an 1980s Mercedes Benz. The LED volume display is way too bright but that is the only complaint I could throw at it. I don't have much to compare it to, was using an O2 amp with a Burson v5i OP amp and was happy but you know, the audio itch. So after getting a pair of planars I wanted to "push" them and this amp kept coming up here and there with great reviews from everyone that talked about it. For the price it's a powerhouse.  They definitely add stage to an already pretty wide stage presence M1060 and my HD58X benefited as well.  You gotta go balanced in though, so to get this I had to fork money on a DAC; Gheshelli Labs ENOG2, cables and of course the tubes. No point getting this if you're not going to play with your tubes.  Currently using some 1960s Sylvania tubes made for Baldiwn organs, they sound good. Next on deck is a pair of GEs from the same era.
> 
> Only 2 watts but for 32 Ohm planars that's plenty of power.  Totally enjoying detail I'd never heard in my music before, glad I got here without spending too much on other stuff... man Hi-Fi was expensive then and it's expensive now. My wallet hates the internet.



I like Sylvania on the TA-10, the ones I used were warm with a thick low end. I got a solid state tube which is 12ax7, sounds very good and seems to be better after a little burn in.

https://www.ebay.com/itm/AMT-ELECTRONICS-WARMSTONE-12AX7-WS-WARM-STONE-SOLID-STATE-TUBE-2017-improved/152713381371?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649


----------



## dB Cooper

FireLion said:


> I like Sylvania on the TA-10, the ones I used were warm with a thick low end. I got a solid state tube which is 12ax7, sounds very good and seems to be better after a little burn in.
> 
> https://www.ebay.com/itm/AMT-ELECTRONICS-WARMSTONE-12AX7-WS-WARM-STONE-SOLID-STATE-TUBE-2017-improved/152713381371?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649



I had no idea that such a thing existed with the solid state tubes!  I'm really liking the Sylvania tubes actually.  A general question about tubes, if you find something you like (and the price is right) is it worth stoking up? What's the average lifespan of a tube that sees a couple of hours daily use?


----------



## omegaorgun (Sep 4, 2019)

dB Cooper said:


> I had no idea that such a thing existed with the solid state tubes!  I'm really liking the Sylvania tubes actually.  A general question about tubes, if you find something you like (and the price is right) is it worth stoking up? What's the average lifespan of a tube that sees a couple of hours daily use?



Not sure, It is good to have a few. I tend to look out for lots that are up for auction on ebay. I know one guy got 12 tubes for $23 posted and it had a few matching pairs the total value was many times what he paid. The advantage to the warmstone is it has tube like properties but won't wear out, it is pricey but same as a genalex gold lion. It has nice sound-stage and clarity, I am also a op-amp rolling fan so wonder what tech is in this.

http://amtelectronicsusa.com/productpage12AX7WS.html


----------



## Ultrainferno

Ultrainferno said:


> Today we look at the Xduoo HK TA-20 tube headphone amp. A first look, now on Headfonia!
> 
> https://www.headfonia.com/xduoo-ta-20-picture-sunday/
> 
> Of course we'll have a full review soon



Today we have the full review online: https://www.headfonia.com/xduoo-ta-20-review/


----------



## omegaorgun (Sep 5, 2019)

Ultrainferno said:


> Today we have the full review online: https://www.headfonia.com/xduoo-ta-20-review/



I swear by the TA-10 and with something like an SU-8 or even the SDAC-B the TA-20 might be one of the more intriguing tube hybrids. The warmstone 12ax7's might be nice on that. Any 12AX7 tube will add a little more gain for cans like the T50RP and all of it's evolved variants. Any planar I have used on the TA-10 sound amazing and also the Fostex bio-dynamics also get a new layer to them where the crazy bass gets somewhat controlled and imaging is improved or becomes a little more 3D like.


----------



## cleg

My video about TA-20


----------



## Gayron

Hi guys, I just bought a TA-20 to try out the tube sound, and it seems I got a faulty device. Once I turn it on, the tubes start producing some very tiny lights, which come off in a few second, and at this very moment the Protect indicator starts blinking, and in a few more minutes the unit turns off. Regarding this indicator the manual only says that "The device is abnormal". What do you think could be the problem? Could it be because the tubes are faulty, and if I replace them things are gonna be alright? Thanks!


----------



## dpump (Sep 26, 2019)

Try removing the tubes and then turn the amp on and see what happens. This will tell you if you have a tube which is causing the problem. On my TA-20 once I turn it on there is a short delay and then the display turns on. A few seconds later there is another click which I think is a relay which activates the headphone output. If you have the display lighting up without the tubes installed then you should be good with another set of tubes.


----------



## Gayron (Sep 27, 2019)

dpump said:


> Try removing the tubes and then turn the amp on and see what happens. This will tell you if you have a tube which is causing the problem. On my TA-20 once I turn it on there is a short delay and then the display turns on. A few seconds later there is another click which I think is a relay which activates the headphone output. If you have the display lighting up without the tubes installed then you should be good with another set of tubes.


Well, the problem was kinda solved last night. And it wasn't the obvious solution. I only did what I did out of desperation. I absolutely sure that the tubes were sitting correctly in their sockets and pushed in to the right depth, I checked that multiple times. But after I adjusted and tilted the tubes a tiny bit backwards in their sockets, bloody device started up alright. It's a relieve, but the unpleasant aftertaste remains about the device.


----------



## S Crowther

Gayron said:


> Well, the problem was kinda solved last night. And it wasn't the obvious solution. I only did what I did out of desperation. I absolutely sure that the tubes were sitting correctly in their sockets and pushed in to the right depth, I checked that multiple times. But after I adjusted and tilted the tubes a tiny bit backwards in their sockets, bloody device started up alright. It's a relieve, but the unpleasant aftertaste remains about the device.


The trouble shooting guide for the amp states that one of the first things to check is whether the tubes are seated properly.


----------



## Gayron

S Crowther said:


> The trouble shooting guide for the amp states that one of the first things to check is whether the tubes are seated properly.


Yes I read that, but I checked the tubes a few times, and I took them out and pushed back with an effort. What also confused me was the explanation given in the manual regarding the "Protect" indicator, it just said the device is abnormal. So I guess my inexperience with tube amps multiplied by confusing manual gave this result when I thought my unit was faulty. Thanks everybody.


----------



## S Crowther

Gayron said:


> Yes I read that, but I checked the tubes a few times, and I took them out and pushed back with an effort. What also confused me was the explanation given in the manual regarding the "Protect" indicator, it just said the device is abnormal. So I guess my inexperience with tube amps multiplied by confusing manual gave this result when I thought my unit was faulty. Thanks everybody.


No problems. This is my first tube amp also. Incidentally I have changed the tubes to Amperex Bugleboy with a noticeable improvement in sq.
Bought them on Ebay where there is a range of different tubes to try at reasonable prices. They seem to have different sound signatures so you can experiment to find ones that suit your system/, preferences


----------



## Gayron

S Crowther said:


> Incidentally I have changed the tubes to Amperex Bugleboy with a noticeable improvement in sq.
> Bought them on Ebay where there is a range of different tubes to try at reasonable prices. They seem to have different sound signatures so you can experiment to find ones that suit your system/, preferences


Thank you for the advice! I will look up these tubes. I also ordered a set of replacement tubes Golden Lion Genalex ECC82, somebody recommended them in a comment on Aliexpress.


----------



## S Crowther (Sep 28, 2019)

Gayron said:


> Thank you for the advice! I will look up these tubes. I also ordered a set of replacement tubes Golden Lion Genalex ECC82, somebody recommended them in a comment on Aliexpress.


Yes, I have heard good things about the Gold Lions also.
I saw advice only to buy tubes described as tested matched pairs and from a seller with a history.


----------



## ricinus13

I can confirm from experience, the Gold Lions are great. I have 4 tubes for my TA-10 including stock, and the GLs take the cake for me. But I'd also love to try one of those solid state tubes, I'm morbidly curious what they do to the sound. Would love to hear some thoughts on them.


----------



## cleg

*xDuoo TA-20 text review by Porta.Fi*​
English: https://porta.fi/xduoo-ta-20-headphone-amp-review-tubes-for-all/
Russian: https://porta.fi/ru/obzor-usilitelya-dlya-naushnikov-xduoo-ta-20-plyus-lampizacziya-vsej-strany/


----------



## ricinus13

Great review, I'd be interested in an update with said Mullard tubes. I've been thinking of trying even more tubes for my TA-10.


----------



## judas7

I have a Xduoo TA-20 on the way, and I too am interested in other's experience with tubes. I'm new to tube rolling, so I'm not looking to drive blind. I have a RME ADI-2 DAC with Fostex TR-X00 Ebony and Sennheiser HD660s cans. What I want from this combo is fuller sound down low on the Fostex and the same for the HD660. 

So far, the Fostex simply haven't delivered the bass I was expecting and the Senn's simply need bass, period. I love the Senn's for a lot of things and wanted the Fostex to be great for specifically low stuff from electronica, funk and hip hop. 

So, where should I start on replacing the stock tubes?


----------



## dB Cooper (Oct 3, 2019)

judas7 said:


> I have a Xduoo TA-20 on the way, and I too am interested in other's experience with tubes. I'm new to tube rolling, so I'm not looking to drive blind. I have a RME ADI-2 DAC with Fostex TR-X00 Ebony and Sennheiser HD660s cans. What I want from this combo is fuller sound down low on the Fostex and the same for the HD660.
> 
> So far, the Fostex simply haven't delivered the bass I was expecting and the Senn's simply need bass, period. I love the Senn's for a lot of things and wanted the Fostex to be great for specifically low stuff from electronica, funk and hip hop.
> 
> So, where should I start on replacing the stock tubes?



Have you tried to eq the sound with your RME DAC?  That's the first thing I'd experiment with.  Anyway, this is a good general guide to 127AU tubes, I've been using to make my purchasing decisions. Like everything else in life, ymmv but I've found it good enough for the handful of tube sets I've gotten so far.


----------



## judas7

That is very helpful. Thank you DB! Based on that info, I'm looking to start in the bottom left of that quadrant. Any recommendations on where to look/buy?

The RME is a really good amp. It sounds clean and I can EQ it if I want to change sound. However, there's something extreme sexy about the tubes. I will continue to use the RME amp for certain applications and music styles. I simply want the xduoo for the change up and exploration. I want the tube setup to provide a rich meaty sound with bass I can feel.


----------



## dB Cooper (Oct 3, 2019)

To start out I bought a pair of early 60's GE tubes and a pair of these Sylvania, both relatively inexpensive and from opposing quadrants given the chart. One thing I'll say is that the amp is warm in nature so a warm tube will probably just add more warmth.  Turned out I really liked the Sylvania tube they were NOS and have a very musical quality to them so that's what I kept in there.  https://www.ebay.com/itm/Vintage-Sy...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

The Mullards though in the bottom left quadrant are sought after but they're costly, I'd love to try those but too rich just to "try" especially since I'm pretty happy as is. My suggestion is start cheap and see if you like that, you can get into the > $100 a pair of tubes quickly!  It's a great amp, I'm loving it. It does get WARM though,m just the nature of the A/B type amp with the tubes, the tubes actually get hot not just warm!


----------



## Gayron

Hi everybody, I recently had an issue with TA-20 when the amp wouldn't work and the Protect indicator constantly blinking, and which was solved by slightly adjusting tubes position (slightly pushing to the side). Once I breathed with relief thinking I won't have to send it back to China, the device started acting again. When I turned it on last morning the Protect indicator started again, and this time I spent good ten minutes adjusting the tubes in their sockets and the bloody thing wouldn't start until I switched back to stock tubes. Next time I, again, install my custom Gold Lion tubes, and TA-20 suddenly working! I switch it off and on - not working, switch off, adjust tubes, switch on - working. Am I doing something wrong or is my device defective? What do you guys think. Also I noticed that the Gold lions produce a lot of hiss with my Denons D9200 even with iematch. Why? Thank you!


----------



## S Crowther

Gayron said:


> Hi everybody, I recently had an issue with TA-20 when the amp wouldn't work and the Protect indicator constantly blinking, and which was solved by slightly adjusting tubes position (slightly pushing to the side). Once I breathed with relief thinking I won't have to send it back to China, the device started acting again. When I turned it on last morning the Protect indicator started again, and this time I spent good ten minutes adjusting the tubes in their sockets and the bloody thing wouldn't start until I switched back to stock tubes. Next time I, again, install my custom Gold Lion tubes, and TA-20 suddenly working! I switch it off and on - not working, switch off, adjust tubes, switch on - working. Am I doing something wrong or is my device defective? What do you guys think. Also I noticed that the Gold lions produce a lot of hiss with my Denons D9200 even with iematch. Why? Thank you!


I think this may be a case of defective tubes or  just one tube.
I have read that hissing is a known symptom of a failing tube, particularly if it gradually gets worse. It happened to me with a set of tubes I bought on AliExpress.
This could well explain the problems you have encountered.


----------



## thesheik137

Just had to drop in here and say that the Xduoo TA20 was a great buy for me.

Running Hiby R5 through 4.4 to dual xlr into the TA20 and listening with the Focal Elex via 4 pin xlr is an outstanding setup. The Xduoo brings everything I could want from an amp for these cans. Great power, tone, dynamic control etc. I am also using it as a preamp for my speaker setup and it improves it the sound greatly. I am very satisfied listening with the TA20 in the chain and am not looking to upgrade soon. Xduoo continues to churn out great products at reasonable prices, but seem to get overshadowed by other big names like fiio.


----------



## dB Cooper

It is very much a sleeper amp. Surprised that it never took off in the community, since getting mine I've never thought about upgrading an amp again.


----------



## Evaherbiz

Thanks @thesheik137. Will this same set up work with Hiby R6 Pro through 4.4?
Will it pose a problem since R6 Pro 4.4 is not line out.



thesheik137 said:


> Just had to drop in here and say that the Xduoo TA20 was a great buy for me.
> 
> Running Hiby R5 through 4.4 to dual xlr into the TA20 and listening with the Focal Elex via 4 pin xlr is an outstanding setup. The Xduoo brings everything I could want from an amp for these cans. Great power, tone, dynamic control etc. I am also using it as a preamp for my speaker setup and it improves it the sound greatly. I am very satisfied listening with the TA20 in the chain and am not looking to upgrade soon. Xduoo continues to churn out great products at reasonable prices, but seem to get overshadowed by other big names like fiio.


----------



## thesheik137

Evaherbiz said:


> Thanks @thesheik137. Will this same set up work with Hiby R6 Pro through 4.4?
> Will it pose a problem since R6 Pro 4.4 is not line out.


It should work fine, just turn the volume up to 100 and you're set.


----------



## Evaherbiz (Oct 21, 2019)

thesheik137 said:


> It should work fine, just turn the volume up to 100 and you're set.


Thank you Bro. Getting that 4.4mm to dual xlr cable soon.

And oh by the way, will it be too much power (and issues of double amping) for an iem; Like fearless s8f and the likes?


----------



## thesheik137

Evaherbiz said:


> Thank you Bro. Getting that 4.4mm to dual xlr cable soon.
> 
> And oh by the way, will it be too much power (and issues of double amping) for an iem; Like fearless s8f and the likes?


Yes, there will be noise floor. But if you use an impedance adapter (100-150ohm) that can be resolved easily.


----------



## Evaherbiz

thesheik137 said:


> Yes, there will be noise floor. But if you use an impedance adapter (100-150ohm) that can be resolved easily.


Sure thanks


----------



## Wiljen

I have been working my way through tube rolling the Xduoo amps.  The first installment was the 5654 tubes and second the 12au7s.  I am working on a Ta-03s installment now but will be awhile as just getting a start on it.   
Here is the 1st installment:  https://audiofool.reviews/tube-rolling-the-xduoo-ta-02-and-ta-05-amplifiers/
and the 2nd:   https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/

Hope you enjoy it, I had fun doing the testing.

I started to post here under the Head Gear section, but not really a device review as much as a tube review.


----------



## thesheik137

Wiljen said:


> I have been working my way through tube rolling the Xduoo amps.  The first installment was the 5654 tubes and second the 12au7s.  I am working on a Ta-03s installment now but will be awhile as just getting a start on it.
> Here is the 1st installment:  https://audiofool.reviews/tube-rolling-the-xduoo-ta-02-and-ta-05-amplifiers/
> and the 2nd:   https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/
> 
> ...


Great post, man. Saves me a lot of time(/money) getting too deep into tubes. I'm going to go for your Amperex recommendation for the TA-20.


----------



## Wiljen

The Amperex are a great balance in the Ta-20.  If using a dry DAC (sabre) they bring just enough warmth back to it to keep it from sounding quite so clinical, and if using an AKM or CL dac, they add a touch of extra warmth that is nice without going overboard like the Mullard can.   If you love a warm tone and are using a clinical dac, grab the Mullard or Brimar as they really balance it off well and give the sound a bit more warmth and thickness.


----------



## thesheik137

I'm using CL dac, but I'm listening mainly with the Focal Elex so added warmth and body is welcome.


----------



## PinkyPowers

*To Burn and Glow – A Review of the XDuoo TA-20*
​


----------



## S Crowther

Any news when the TA-30 will appear?


----------



## Wiljen

S Crowther said:


> Any news when the TA-30 will appear?



Supposed to start showing up sometime right around Thanksgiving (11/28) was the last I heard.


----------



## Wiljen

Posted the review of the Ta-03s and the tube rolling article for it on my blog today.  The tube rolling part has been tons of work to keep up with each pair and really give them time to settle in, but it has been a lot of fun doing it too.  
https://audiofool.reviews/2019/11/05/xduoo-ta-03s/
https://audiofool.reviews/tube-rolling-the-xduoo-ta-03s/

Hope you guys find it useful.

W


----------



## SoyBean0809

Wiljen said:


> https://audiofool.reviews/2019/11/05/xduoo-ta-03s/
> https://audiofool.reviews/tube-rolling-the-xduoo-ta-03s/


Huge thanks to your work! The post about tube rolling is really helpful. But when click on the other link it raised a "503 service unavailable" error, I don't know if it is due to my network connection or something else, could you please check it and it would be nice to know more about your opinion towards this product


----------



## Wiljen

SoyBean0809 said:


> Huge thanks to your work! The post about tube rolling is really helpful. But when click on the other link it raised a "503 service unavailable" error, I don't know if it is due to my network connection or something else, could you please check it and it would be nice to know more about your opinion towards this product



fighting with ISP right now to get that fixed. They moved to a new platform and none of the content that has been added since works.


----------



## Wiljen

Should be fixed now-  was a problem with a wordpress plug-in for galleries.  Pictures not as pretty at the moment, but at least they work.


----------



## SoyBean0809

Wiljen said:


> Should be fixed now-  was a problem with a wordpress plug-in for galleries.  Pictures not as pretty at the moment, but at least they work.


Appreciate it!


----------



## arielext

Silly how quiet this thread is. The TA-20 is such a nice amp for hungry headphones like the beyerdynamic T1.2.
Right now I'm rocking with a pair of JAN Sylvana 12AU7WA tubes and the combination has such a smooth sound.


----------



## Wiljen

The Ta-20 and the Ta-03s are both really good amps for the price and can be made even better with the right tubes.  I'm not sure why they have not gotten the traction that some others have.  I think they are every bit the amp that the little dots, or dark voices are, and nip at the heels of some of the bigger more costly brands.


----------



## Shane D

I bought a new to me TA-20 last night. I will compare it to my Vali 2 and keep the winner.
The TA-20 looks cooler, has more power and is balanced.
The Vali 2 has a huge following and a pretty good track record.

It will be interesting.

Shane D


----------



## Wiljen

Shane D said:


> I bought a new to me TA-20 last night. I will compare it to my Vali 2 and keep the winner.
> The TA-20 looks cooler, has more power and is balanced.
> The Vali 2 has a huge following and a pretty good track record.
> 
> ...



Having had both, prepare to sell the Vali.


----------



## Shane D

Wiljen said:


> Having had both, prepare to sell the Vali.



Honestly, I am looking for "tubey" or at least "tube like". I like my Vali 2 but it sounds like a nice SS amp to me. My Cavalli LCX sounds "tubier" to me. I get that a hybrid will not do Exactly what I want, but with all my HP's being around 32 Ohm, I am limited in my choices. And I am not going to spend hundreds on tubes for a cheap amp, hoping that I can change it's sound substantially.

So far Shenzhen is really impressing me with the SMSL SU-8 and the SMSL SP200. Hopefully I'll be 3 for 3.

Shane D


----------



## Wiljen

Shane D said:


> Honestly, I am looking for "tubey" or at least "tube like". I like my Vali 2 but it sounds like a nice SS amp to me. My Cavalli LCX sounds "tubier" to me. I get that a hybrid will not do Exactly what I want, but with all my HP's being around 32 Ohm, I am limited in my choices. And I am not going to spend hundreds on tubes for a cheap amp, hoping that I can change it's sound substantially.
> 
> So far Shenzhen is really impressing me with the SMSL SU-8 and the SMSL SP200. Hopefully I'll be 3 for 3.
> 
> Shane D



If you really want tube warmth from the Ta-20, I recommend either the Mullard or the Sylvania black-plate 12au7s.  Mullards will be a bit more tubey but at a bit higher price.  The Sylvania will usually go in the $15-20 per tube in matched pairs and are a great inexpensive option.


----------



## Shane D

Wiljen said:


> If you really want tube warmth from the Ta-20, I recommend either the Mullard or the Sylvania black-plate 12au7s.  Mullards will be a bit more tubey but at a bit higher price.  The Sylvania will usually go in the $15-20 per tube in matched pairs and are a great inexpensive option.



That would be a very affordable option if it gets me where I want to go. Thanks!

Shane D


----------



## Shane D

Wiljen said:


> If you really want tube warmth from the Ta-20, I recommend either the Mullard or the Sylvania black-plate 12au7s.  Mullards will be a bit more tubey but at a bit higher price.  The Sylvania will usually go in the $15-20 per tube in matched pairs and are a great inexpensive option.



Would these be good ones?
Mullard 12AU7, Matched Pair https://www.amazon.ca/dp/B079SXZ5Y7/ref=cm_sw_r_em_apa_i_.16hEbYNHB200

Shane D


----------



## Wiljen

Shane D said:


> Would these be good ones?
> Mullard 12AU7, Matched Pair https://www.amazon.ca/dp/B079SXZ5Y7/ref=cm_sw_r_em_apa_i_.16hEbYNHB200
> 
> Shane D



No, those are current re-issue tubes made at the Reflector plant in Russia and don't have the same tone as the earlier British made tubes.  Sorry should have mentioned that the current made ones are Mullard in name only and not really in quality or tone.    Here is a better example:  and no I'm not suggesting you buy them from here, just that these are what you are looking for : https://www.ebay.com/itm/MULLARD-WE...449710?hash=item469c16c92e:g:HsAAAOSw4RNdZVc9


----------



## Shane D

The TA-20 amp went on Drop to day for $296.00.

Shane D


----------



## dpump

There's a used TA-20 in the classifieds for $260 with a pair of Amperex 12AU7. Someone should buy this ASAP!


----------



## Wiljen

I got a new toy today.


----------



## Shane D

Wiljen said:


> I got a new toy today.


Wow! That is a very expensive new toy. Sound better than the TA-20?

Shane D


----------



## Wiljen

I got lucky and Xtenik sent me one in exchange for doing some tube rolling and reviewing of it.   It is early in my listening for sure but first impressions are:

Best Xduoo product for sound quality to date, very clean sounding and tons of detail.  So much so that trading the internal dac for the Burson Swing with the upgraded discrete op-amps is a very minor upgrade.
The thing is a beast in the amp section.  I had to set Foobar to -10db to have enough usable range of volume adjustment for things like the Cascades,  the He560 is at 80dB at about 20% on the volume knob and even the vaunted He6 needs a bit less than 50% to be at a comfortable listening level.   I popped a Sylvania 5193 (milspec 5u4gb) in the rectifier position and ran some tests to look at output power.  It measured 3.2 Watts output with a 32Ohm load and was still over 1 Watt output with a 300 Ohm load.  

I have at least 9 different 5u4g or 5u4gb tubes I am going to roll through it and a couple of pairs of 12au7s for that part of the testing (Telefunken ribbed plates and Mullard M8136 as these two are classically the best of the 12au7s)  that should give a pretty clear picture of how sag in the rectifier is impacting sound of the amp.   I also have my normal assortment of 15 different 12au7 pairs to roll through and take some listening notes on.    Probably be mid February before the tube rolling article is published as I have a few 100 hours of listening to do.

W


----------



## Shane D

Wiljen said:


> I got lucky and Xtenik sent me one in exchange for doing some tube rolling and reviewing of it.   It is early in my listening for sure but first impressions are:
> 
> Best Xduoo product for sound quality to date, very clean sounding and tons of detail.  So much so that trading the internal dac for the Burson Swing with the upgraded discrete op-amps is a very minor upgrade.
> The thing is a beast in the amp section.  I had to set Foobar to -10db to have enough usable range of volume adjustment for things like the Cascades,  the He560 is at 80dB at about 20% on the volume knob and even the vaunted He6 needs a bit less than 50% to be at a comfortable listening level.   I popped a Sylvania 5193 (milspec 5u4gb) in the rectifier position and ran some tests to look at output power.  It measured 3.2 Watts output with a 32Ohm load and was still over 1 Watt output with a 300 Ohm load.
> ...



Cooling looking amp, but I don't need a DAC or Bluetooth. And that price is WAY out of my range.

However, I look forward to reading your review. Especially as it compares to the TA-20.

Shane D


----------



## dpump

I didn't see any mention of the price?


----------



## Shane D

dpump said:


> I didn't see any mention of the price?



On the Shenzhen Audio site it is $710.00 in US$'s.

Shane D


----------



## Wiljen

Finished up my review of the Ta-30 and a ton of tube rolling on it.  it is a beast with over 2 watts into a 150Ohm load in my tests.  Powers the He6 with plenty of headroom too.   Overall, it is impressive.     Review will be up here probably next week, but is on my site now https://audiofool.reviews/2020/02/10/xduoo-ta-30/ 
The tube rolling article will remain on my site only as the 10k limit here and table problems make it too much effort to move.  
https://audiofool.reviews/tube-rolling-the-xduoo-ta-30/

Hope you enjoy reading it and the tube notes help some of you who get one.

W


----------



## bgtip

I need an advice please.
My xDuoo's TA-20 red protect light started flashing today. No sound. Turned the amp on/off couple of times, in vain. Changed the tubes Lt-Rt and it's working fine again.
Background: those are new Amperex tubes, got them yesterday. Played back 12-14 hours non-stop to burn them in. Never happened with the 3 other pair of tubes I have. 

I'd appreciate any advice how to avoid this in future. 

Also I tend to keep TA-20 on all the time, even when not playing back music on it. Should I switch it off when I'm not listening to it?


----------



## Wiljen

Tubes have a limited lifespan so turning them off when not in use for long periods is probably advisable. If I am out of town for the week, I power mine down.  Having said that, I don't turn mine off every night as I think it makes little difference overall and tubes do take time to warm up.  My advice would be if it won't be used for several days power it down, otherwise enjoy it and just know that tubes are consumables and sooner or later will need replacement regardless of whether the device is left on or not.

As for the protect light, that can be a indicator of over-heating and may be that those same tubes will work when the device has time to cool, or it may be that one of the tubes has an issue.   Just for sake of argument, I'd get a pair of inexpensive 12au7s (organ tubes are great for this) and then put in one of the amperex and one of the cheap ones and see if it works.  Don't worry about channel balance etc, just whether it works.  switch sockets with those same two tubes and try again.   Then do the same set of experiments with the other amperex tube and the cheap one.  That should help identify which tube or which socket is at issue.   It may not cure the problem, but it should help narrow it down considerably.


----------



## Gayron

bgtip said:


> My xDuoo's TA-20 red protect light started flashing today. No sound.


I had similar problem with the Protect light. Only I had it right when I first got my unit. At one moment I was able to overcome this by adjusting tubes in their sockets, but every other time I turned my TA20 on it wasn't working, and I had to repeat this annoying tube adjusting procedure. Turned out my unit was faulty. I had to send it back to the Aliexpress seller, and they had Xduoo repair it. It was a major pain.


----------



## bgtip

Wiljen said:


> Tubes have a limited lifespan so turning them off when not in use for long periods is probably advisable. If I am out of town for the week, I power mine down.  Having said that, I don't turn mine off every night as I think it makes little difference overall and tubes do take time to warm up.  My advice would be if it won't be used for several days power it down, otherwise enjoy it and just know that tubes are consumables and sooner or later will need replacement regardless of whether the device is left on or not.
> 
> As for the protect light, that can be a indicator of over-heating and may be that those same tubes will work when the device has time to cool, or it may be that one of the tubes has an issue.   Just for sake of argument, I'd get a pair of inexpensive 12au7s (organ tubes are great for this) and then put in one of the amperex and one of the cheap ones and see if it works.  Don't worry about channel balance etc, just whether it works.  switch sockets with those same two tubes and try again.   Then do the same set of experiments with the other amperex tube and the cheap one.  That should help identify which tube or which socket is at issue.   It may not cure the problem, but it should help narrow it down considerably.


I'd like to thank you for your tube rolling article for TA-20. I bought the Amperex pair after reading it. The Amperex achieved the sound I crave - wide 3D soundstage with warmth and bass.


----------



## Wiljen

bgtip said:


> I'd like to thank you for your tube rolling article for TA-20. I bought the Amperex pair after reading it. The Amperex achieved the sound I crave - wide 3D soundstage with warmth and bass.



I'm glad you found it useful,  I do think tube rolling is under appreciated for the differences it can make in the overall sound and there are lots of great tubes out there that don't have to cost a ton to get into it.

W


----------



## TheBrandon

Good read here everyone thank you! Currently my setup is extremely sterile in regards to my HD800S and I’ve been exploring the TA-20 as my first tube amp as well as the for sale market here.

EL Dac is what I am using and a JDS Atom. My target is widest sound stage, warmer sound, no loss of detail and it’s huge for me not to lose imaging as I can get that from my T1 Version 2.  With this DAC, Sylvanian tubes mentioned?  Thoughts on if I should go for this or hang out on the FS side of the forums for a bit until I see something more fitting (historically) in my price range for the HD800/S? Is the TA-20 punching above its weight class in price compared to other tube amps? I’m more of a buy once cry once mindset but always looking for a gem. I was trying hard to track down a ZDT Jr as that seemed like a solid fit and for a good price. Was not wanting to go over a thousand

Any experiences where this is preferred over more tenured brands that have been loved for that tube magic you’ve preferred the TA-20?

Silly question, if I run RCA in from DAC I can use balanced out to headphones correct? Thanks again all.

The TA-30 would have been my first choice but not going that high considering the used market and not knowing much about the brand.


----------



## Wiljen

TheBrandon said:


> Good read here everyone thank you! Currently my setup is extremely sterile in regards to my HD800S and I’ve been exploring the TA-20 as my first tube amp as well as the for sale market here.
> 
> EL Dac is what I am using and a JDS Atom. My target is widest sound stage, warmer sound, no loss of detail and it’s huge for me not to lose imaging as I can get that from my T1 Version 2.  With this DAC, Sylvanian tubes mentioned?  Thoughts on if I should go for this or hang out on the FS side of the forums for a bit until I see something more fitting (historically) in my price range for the HD800/S? Is the TA-20 punching above its weight class in price compared to other tube amps? I’m more of a buy once cry once mindset but always looking for a gem. I was trying hard to track down a ZDT Jr as that seemed like a solid fit and for a good price. Was not wanting to go over a thousand
> 
> ...



Your best bet is to hit several meets or shows and audition as much as possible.  If that isnt an option, make sure you buy from a dealer with a liberal return policy.  

Ta-30 doesn't have balanced output either - the only headphone out is a standard 1/4 inch single ended jack.    If you want balanced, I think the Ta-20 is easily the most cost effective option as most inexpensive tube amps don't offer balanced output.  Bottlehead for example, the Mainline is their balanced design at $1300 while the crack is single ended and starts about about $350  In the Schitt line, you hit the Mjolnir before you have tubes and balanced output.   On the solid state side, things like the THX amps are also worth auditioning.


----------



## bgtip

TheBrandon said:


> ... Silly question, if I run RCA in from DAC I can use balanced out to headphones correct? ...


Yes you can run RCA in from the DAC and listen to the balanced out. This is what I used to do before buying my SMSL SU-8. Fully balanced setup however sounds better to me, especially the soundstage.


----------



## TheBrandon

bgtip said:


> Yes you can run RCA in from the DAC and listen to the balanced out. This is what I used to do before buying my SMSL SU-8. Fully balanced setup however sounds better to me, especially the soundstage.




With the SMSL SU-8 what Enhancement options do you have under "properties"?  If you right click on speaker, open volume mixer, click on the device (not sure how it would be labeled, probably Speakers") and choose enhancements.  What all do you see in there?  What driver is the SMSL 8 using?  I have one massive issue with my EL DAC but I believe it may be a few pieces of software specifically or Win 10 64 1909 problem.  Everything is pretty great in general with it.  Did a complete rebuild and so on but wouldn't mind at all trying another DAC.  

My motherboard has the ESS9118 how does this compare to the SMSL ES9038Q2M?  My board has WIMA and Nichicon gold caps and its not bad at all quite honestly but the EL DAC seems clearer. 

Unfortunately the way I have had to have it set up due to an application is through optical from board to EL DAC to Amp.  This is why I am inquiring about the drivers and options on SMSL.  I need Loudness Equalization with that specific application. I am trying to get an answer on how the digital audio stream is handled from the vendor but this means it needs to see an engineer or developer and well... that may or may not ever happen.  I have a workaround though with different driver but it should not be this way at all.   

I received my TA-20 today!!  It was $250 but open box.  I am just really really hoping its good to go and was told it was like new.  Fingers crossed, I'll be setting it up soon.


----------



## greenarrow

Just received my first tubes ..





Any good recommdations on better tubes over the default ones? The default tubes are pairing with HE-4XX, TakStar HF580 and DT880 Pro. What I'm looking for are tubes which can give me good bass, soundstage and clear mid and high. No audiophile here, just general listening of songs from the 50s till 70s.


----------



## Wiljen

greenarrow said:


> Just received my first tubes ..
> 
> 
> 
> Any good recommdations on better tubes over the default ones? The default tubes are pairing with HE-4XX, TakStar HF580 and DT880 Pro. What I'm looking for are tubes which can give me good bass, soundstage and clear mid and high. No audiophile here, just general listening of songs from the 50s till 70s.



The Ta-03s has a lot of good choices for the pre-amp tube, but not as many options for the power tubes.  I wrote up my tube rolling experience with it.  
https://audiofool.reviews/tube-rolling-the-xduoo-ta-03s/


----------



## bgtip

TheBrandon said:


> With the SMSL SU-8 what Enhancement options do you have under "properties"?  If you right click on speaker, open volume mixer, click on the device (not sure how it would be labeled, probably Speakers") and choose enhancements.  What all do you see in there?  What driver is the SMSL 8 using?  I have one massive issue with my EL DAC but I believe it may be a few pieces of software specifically or Win 10 64 1909 problem.  Everything is pretty great in general with it.  Did a complete rebuild and so on but wouldn't mind at all trying another DAC.
> 
> My motherboard has the ESS9118 how does this compare to the SMSL ES9038Q2M?  My board has WIMA and Nichicon gold caps and its not bad at all quite honestly but the EL DAC seems clearer.
> 
> ...


I don't have SMSL SU-8 anymore. I don't know if there are any Enhancements under Sound Properties, and I have never needed any. It doesn't need any drivers but if you wish you can download an XMOS driver from here http://www.smsl-audio.com/download.asp?p=1. I feeded TA-20 via ASIO in foobar2000 (highlighted selection):

I have never used optical output with SMSL SU-8. I didn't have to. USB DAC worked flawlessly and the resulting sound was nothing less than divine.


----------



## AudioProm

I'm considering NOS Brimar CV4003 for xDuoo TA-20. Anyone have any experience with this setup?
The chain is Bifrost 2 - xDuoo TA-20 - Ananda (mainly) or Verite open. I'm looking for a great sound stage without sacrificing smoothness and low end too much. 
I saw the guide on early post but it doesn't say much about sound stage and imaging properties of the tubes.


----------



## Wiljen

I've got a few Brimar 12au7 types and generally they are a very solid tube,  not quite as warm as a Mullard but not as clinical as the Telefunken can sound.  Overall a good compromise tube.   They tend to be similar to the Amperex which is another favorite but both are climbing in price.


----------



## TheBrandon

Wiljen said:


> I've got a few Brimar 12au7 types and generally they are a very solid tube,  not quite as warm as a Mullard but not as clinical as the Telefunken can sound.  Overall a good compromise tube.   They tend to be similar to the Amperex which is another favorite but both are climbing in price.


How is the sound stage compared to stock? I’m looking for widest sound stage but not wanting to spend a fortune (frontlines fighting covid 19 so who knows if I’ll have much time to enjoy it or quite honestly what the future holds) and exactly where people are buying these.

As an aside, I’ve refrained from commenting without really spending time putting it through the paces, not that my opinion matters but I really like TA-20. This thing is a massive sleeper and I feel that is an understatement. I’m not trying to sell it but super happy I have one.

Amazing how some people do not like tubes and others love them. Is there data or a study regarding hearing capabilities and what a person is capable of hearing with tubes? Maybe it’s just the added distortion on otherwise overly analytical headphones? I know with my Beyerdynamic T1.2 it’s amazing regardless of amp. HD800S definitely prefers tubes to my ears but great regardless and can be dependent on what media I’m listening too.

I swear if this had a different name it’d have taken off more than it has based on what I’m seeing. Darkvoice sounds cool. Atom sounds cool. TA-20 is fine but Xduoo sounds like hot turds. Crazy how much that matters but it really does imo.


----------



## Wiljen

TheBrandon said:


> How is the sound stage compared to stock? I’m looking for widest sound stage but not wanting to spend a fortune (frontlines fighting covid 19 so who knows if I’ll have much time to enjoy it or quite honestly what the future holds) and exactly where people are buying these.
> 
> As an aside, I’ve refrained from commenting without really spending time putting it through the paces, not that my opinion matters but I really like TA-20. This thing is a massive sleeper and I feel that is an understatement. I’m not trying to sell it but super happy I have one.
> 
> ...



Stage on the Brimar 12au7s I have tried is quite good, maybe not quite as wide as the Telefunken but certianly near the top of the class.    As for where to get them, you can gamble with places like ebay but I find you are generally better off paying a dollar or two more to go with a reputable seller who knows how to properly test and rate tubes.   Just because somebody puts test values on the advertisement doesn't mean they are correct or that the tube is good.    Buy from sellers who offer returns and refunds as the reputable sellers will happily take a return or refund a bad tube.


----------



## TheBrandon

Wiljen said:


> Stage on the Brimar 12au7s I have tried is quite good, maybe not quite as wide as the Telefunken but certianly near the top of the class.    As for where to get them, you can gamble with places like ebay but I find you are generally better off paying a dollar or two more to go with a reputable seller who knows how to properly test and rate tubes.   Just because somebody puts test values on the advertisement doesn't mean they are correct or that the tube is good.    Buy from sellers who offer returns and refunds as the reputable sellers will happily take a return or refund a bad tube.



Any suggestions for a reputable seller?  Embarrassingly, I am not sure who is reputable or is it just highly rated eBay sellers?  I'm sorry, I'm frontlines for COVID19 fight and haven't had time for research.  Pretty sure though I am going to have plenty of down time soon just hopefully God willing, not permanently. I did finally convince my wife to try my setup and she was actually floored so she could always enjoy it!  Her reluctance always kinda cracked me up because of how much she listens to music but always seemed to have the attitude "all sound the same".  Man I enjoyed that moment!!  Thanks again!!


----------



## Wiljen (Mar 28, 2020)

Tubeworldexpress, tubemonger, upscale audio, and audiotubes.com  to name a few - shop around for the best price.


----------



## Wiljen

Wiljen said:


> Tubeworldexpress, tubemonger, upscale audio, and audiotubes.com  to name a few - shop around for the best price.



Ebay Sellers I have had good luck with include: oldtymes, ibismachine, Jaelectronics, jpcollectibles, tube-finder, and murphken


----------



## AudioProm (Apr 2, 2020)

Wiljen said:


> Stage on the Brimar 12au7s I have tried is quite good, maybe not quite as wide as the Telefunken but certianly near the top of the class.    As for where to get them, you can gamble with places like ebay but I find you are generally better off paying a dollar or two more to go with a reputable seller who knows how to properly test and rate tubes.   Just because somebody puts test values on the advertisement doesn't mean they are correct or that the tube is good.    Buy from sellers who offer returns and refunds as the reputable sellers will happily take a return or refund a bad tube.



I received the NOS Brimar CV4003 yesterday and had a chance to A-B test it against my LYR3 with Psvane CV181-T Mk.2. Just as a reference, my chains are the following:

1. PC - Bifrost 2 [RCA] - LYR3 [Psvane CV181-T Mk.2] - Verite Open
2. PC - Bifrost 2 [XLR] - Xduoo TA-20 [*Nos Brimar CV4003*] [_Single ended out_] - Verite Open

Everything is connected to Furman PST-8D power conditioner.

So far on my initial impression at least, I'm very surprised how similar they both sound on most tracks I listen to.
• Soundstage: No discernible difference between the two. If there's any, I'd give the very slight advantage to Brimars+Xduoo combo
• Imaging: LYR3+Psvane combo wins here. The image separation and layering is better but not much, just enough to perceive.
• Lows: LYR3+Psvane combo slams harder at the same volume level which is not surprising due to the difference of power level. Sub bass extends well for both pairings.
• Mids: Brimars+Xduoo combo has more detail and texture to vocals. Not by much but there's definitely perceivable difference between the two.
• Highs: LYR3+Psvane combo is the clear winner here. The Brimars+Xduoo combo has a bit roll off in this area. They're not extended as well as the other pairing. EQ can probably fix this.

I wonder if the Xduoo TA-20+Brimars will improve after some burn-in. The seller claims they're already went through some burn-in but there's no way to verify until I do the same. I'm hoping the XLR out will improve things further. A tool to volume match will definitely help as well.

As far as the other tubes I've tried with Xduoo are the default Chinese tubes and re-production Gold Lion Genalex ECC82. The Chinese tubes are just bad; dead and uninspiring. The Gold Lion pairing is not a good match in my chain. It's a very warm tube and can turn some tracks into a hot mess.

OK, back to listening some more.


----------



## TheBrandon

Ended up getting these, Vintage Sylvania 12AU7A PLATINUM GRADE Preamp Tubes Matched Pair = (ECC82, 6189) for some tubes to play around with (marked Baldwin) supposed to be early 60's.  I ordered a second pair yesterday.  I am absolutely shocked at the difference. I've had these for 4 days now.  Full disclaimer is I have not spent a ton of time listening to music but I did go through a ton of various tracks and due to temp quarantine using these 12+ hours a day (work front line for COVID 19 fight, and personal.  On a rotation from being onsite vs off.)

Here are my observations,

Sound Stage- Wow.  If there is better\wider I am not sure it would be a good thing with my head phones (HD800S).  Would definitely try some day though to see.

Imaging- So far great.  I am going to switch up my listening habits today to verify how much better than stock.  Big improvement though so far but there is some content that really zeros this for me I haven't played with yet.

Lows- Fuller with some layers of depth that does not standout near as much with stock tubes (explosions for example roll vs just boom with layers).

Mids- These are definitely warmer but not over the top.  This brings the HD800S closer to the T1V2 which to my ears have pretty amazing mids and best I've ever heard.

Highs- This is hard for me to comment on clearly.  Better than stock is where I'd leave this and happy to test something if someone had a suggested they want details on with a source.  

In general, in some content it has literally made me paranoid. I am hearing crap I know was there and some I've never knew (there but never paid attention too therefore missing). Things in distance like Coyotes howling and stuff.  Birds popping in hard and stuff like that. Rustling of tent flaps, foot steps.    

I am not very good at describing audio stuff but this feels accurate to me.  Can someone comment on these tubes?  I am curious what I hear is similar to what is expected based on what real experts have said if they have tried them.  Not that it necessarily matters because I am floored at how good these are but because at that point I know what to expect with my ears if someone says, "x,y,z observations all match up but try A,b,c. for upgrade". The pair was $17.95... and if there was a tip jar I'd use it.


----------



## Wiljen

I think the Sylvania's are a great American made tube and are generally underrated when compared to RCA made tubes and certainly the various Euro made models.  I've always found them to be better than average and often near the top of the list.  They tend to last pretty well too which is a nice plus as well.    Organ tubes (Baldwin, Conn) can be fantastic values if NOS or lightly used.


----------



## Currawong

I just had a TA-30 arrive in for review. I've only had it running a couple of hours, so way too early to talk about sound, but it is already showing some promise. 

I'll probably hunt for some tubes once. Hopefully I can still get things mailed to Japan. 

My limited experience of tubes is that Sylvania is a safe bet. With some variance in decades and a few other factors, Sylvania and RCA, and a few other brands all came from the same factories as I understand things.


----------



## ngoshawk (May 12, 2020)

Currawong said:


> I just had a TA-30 arrive in for review. I've only had it running a couple of hours, so way too early to talk about sound, but it is already showing some promise.
> 
> I'll probably hunt for some tubes once. Hopefully I can still get things mailed to Japan.
> 
> My limited experience of tubes is that Sylvania is a safe bet. With some variance in decades and a few other factors, Sylvania and RCA, and a few other brands all came from the same factories as I understand things.



I have had the pleasure of @Wiljen TA-30 in house until mine arrived yesterday. I am using the RCA black plate as pre-amp tubes and a Sylvania 5931 as the rectifier. Quite impressive, so far. I really like the functionality of the TA-30 as well.

Sound is quite wonderful, too. Review coming as well, plus I’ve ordered some extra tubes to roll. Should be fun!


----------



## Wiljen

ngoshawk said:


> I have had the pleasure of @Wiljen TA-30 in house until mine arrived yesterday. I am using the RCA black plate as pre-amp tubes and a Sylvania ecc82 as the rectifier. Quite impressive, so far. I really like the functionality of the TA-30 as well.
> 
> Sound is quite wonderful, too. Review coming as well, plus I’ve ordered some extra tubes to roll. Should be fun!



Should be the Sylvania 5931 rather than ECC82  just for clarification.


----------



## Wiljen

I've been playing with the Ta-30 a good bit before loaning it out to @ngoshawk and my feeling is it benefits from clean power which is no surprise and is at its best with a 5u4Gb rectifier that recovers a bit faster and sags a bit less than the standard 5u4g although I have to say the 5u4g is more impressive visually with its Coke bottle shape.   As for pre-amp tubes, Mullard (early production), Amperex Bugle boys or the Brimar Yellow Ts are probably my favorites as they add a bit of warmth.   The Sylvania 12au7wa (6189) is a great budget option and the Sylvania 5814 offers a bit lower gain and still retains a bit of warmth for those looking to pair more sensitive iems or cans to the Ta-30.


----------



## ngoshawk

Wiljen said:


> Should be the Sylvania 5931 rather than ECC82  just for clarification.



Corrected. See what happens when I try to be an "expert"? I'll leave that to you others. I'm just having fun rolling tubes. This is a good amp.


----------



## ngoshawk

I will mention that the TA-30 is now keeping me from my review units nicely...fortunately I have some that I can combine to "complete the task" double-time, so to speak. This is a very fine unit, with the added benefit of rolling tubes. My tube rolling "extravaganza" will not be nearly as thorough as @Wiljen , but nonetheless, I am impressed so far!


----------



## XeNoNF50

Currawong said:


> I just had a TA-30 arrive in for review. I've only had it running a couple of hours, so way too early to talk about sound, but it is already showing some promise.
> 
> I'll probably hunt for some tubes once. Hopefully I can still get things mailed to Japan.
> 
> My limited experience of tubes is that Sylvania is a safe bet. With some variance in decades and a few other factors, Sylvania and RCA, and a few other brands all came from the same factories as I understand things.



Any brief thoughts on how they sound with the utopias?


----------



## Currawong (May 20, 2020)

With the stock tubes, it is all smoothness. I tried a Mullard metal base GZ34 (worth about $300) in it, and there was some improvement in clarity. I'm waiting for tube adaptors so I can try it with my stock of 6922 and similar tubes.

I have a Sovtek 5AR4 as well, which it seems to do pretty well with, if it isn't as pretty as that big coke-bottle Chinese rectifier. The slightly warm/smooth sound is a nice match with the Utopia.


----------



## Wiljen (May 20, 2020)

Currawong said:


> With the stock tubes, it is all smoothness. I tried a Mullard metal base GZ34 (worth about $300) in it, and there was some improvement in clarity. I'm waiting for tube adaptors so I can try it with my stock of 6922 and similar tubes.
> 
> I have a Sovtek 5AR4 as well, which it seems to do pretty well with, if it isn't as pretty as that big coke-bottle Chinese rectifier. The slightly warm/smooth sound is a nice match with the Utopia.



its a fun beast to tube roll for sure.  I'll be interested in the 6922 tests as I haven't gone down that path yet with mine.  My guess is with the gain on the 6922 being as much higher than it is on the 12au7 that you will lose a good bit of usable volume control as to me it is already on the high side for things like the Cascade and HD700s and unless you are running an He6 (and I do) you  wont get much above about the 10 o'clock position on the volume knob even with the lower Mu 12au7s.


----------



## Currawong

Wiljen said:


> its a fun beast to tube roll for sure.  I'll be interested in the 6922 tests as I haven't gone down that path yet with mine.  My guess is with the gain on the 6922 being as much higher than it is on the 12au7 that you will lose a good bit of usable volume control as to me it is already on the high side for things like the Cascade and HD700s and unless you are running an He6 (and I do) you  wont get much above about the 10 o'clock position on the volume knob even with the lower Mu 12au7s.



That's a good point. The gain is already too high as it is, with it at 9am with the Utopias. I was trying to avoid buying more tubes! I have some 6FQ7s here that have gone unused for years which I was hoping to roll in as well.


----------



## ngoshawk

Currawong said:


> That's a good point. The gain is already too high as it is, with it at 9am with the Utopias. I was trying to avoid buying more tubes! I have some 6FQ7s here that have gone unused for years which I was hoping to roll in as well.



I would add that with the Sylvania rectifier, I can raise the volume beyond 1000, without too much trouble on my LCD-3's. This tube also adds a very nice warmish tone to the overall sound. I am pleased enough that all I did with the original tubes was to check that they worked, then box up. And as @Wiljen stated, changing tubes is definitely a positive here!


----------



## RONJA MESCO

Wiljen said:


> If you really want tube warmth from the Ta-20, I recommend either the Mullard or the Sylvania black-plate 12au7s.  Mullards will be a bit more tubey but at a bit higher price.  The Sylvania will usually go in the $15-20 per tube in matched pairs and are a great inexpensive option.


Options..options...I was looking at the Ta-03s.


Wiljen said:


> Tubes have a limited lifespan so turning them off when not in use for long periods is probably advisable. If I am out of town for the week, I power mine down.  Having said that, I don't turn mine off every night as I think it makes little difference overall and tubes do take time to warm up.  My advice would be if it won't be used for several days power it down, otherwise enjoy it and just know that tubes are consumables and sooner or later will need replacement regardless of whether the device is left on or not.
> 
> As for the protect light, that can be a indicator of over-heating and may be that those same tubes will work when the device has time to cool, or it may be that one of the tubes has an issue.   Just for sake of argument, I'd get a pair of inexpensive 12au7s (organ tubes are great for this) and then put in one of the amperex and one of the cheap ones and see if it works.  Don't worry about channel balance etc, just whether it works.  switch sockets with those same two tubes and try again.   Then do the same set of experiments with the other amperex tube and the cheap one.  That should help identify which tube or which socket is at issue.   It may not cure the problem, but it should help narrow it down considerably.


So wait...you keep your amps on when not in use???Maybe I'm not hearing you right...


----------



## Wiljen

RONJA MESCO said:


> Options..options...I was looking at the Ta-03s.
> 
> So wait...you keep your amps on when not in use???Maybe I'm not hearing you right...



No you heard right, I tend to leave them on unless they will not be used for more than a day or two.  I figure the stress of running 24/7 is about the same as the stress created when first turning them on/off every day so in the end, the difference is only in saving a few bucks on the power bill maybe.


----------



## RONJA MESCO

Wiljen said:


> No you heard right, I tend to leave them on unless they will not be used for more than a day or two.  I figure the stress of running 24/7 is about the same as the stress created when first turning them on/off every day so in the end, the difference is only in saving a few bucks on the power bill maybe.


Wow... That's wild. I would think they'd run out faster this way.... But since you know what's up, I hafta try this out


----------



## XeNoNF50 (May 25, 2020)

My TA-30 arrived but it says 110v instead of 220v on mine. I live in the UK so I guess the sensible thing to do here is to use a step down converter rather than switching the AC lead to one with a UK plug and putting it into the mains?

This specific unit won't support the 230v mains in the UK will it?


----------



## Wiljen

XeNoNF50 said:


> My TA-30 arrived but it says 110v instead of 220v on mine. I live in the UK so I guess the sensible thing to do here is to use a step down converter rather than switching the AC lead to one with a UK plug and putting it into the mains?
> 
> This specific unit won't support the 230v mains in the UK will it?



My understanding is it is an auto-switching power supply and should be fine with 220 but I'd run it by Xduoo just to be positive that they haven't made a design change.


----------



## XeNoNF50 (May 26, 2020)

Wiljen said:


> My understanding is it is an auto-switching power supply and should be fine with 220 but I'd run it by Xduoo just to be positive that they haven't made a design change.



Will send a message but in the meanwhile didn't want to risk it. Got a step down converter. Listening to it tonight was probably a bad idea - this thing is as much as a space heater as my i7-7820x / 1080ti pc and it was 27 degrees Celsius here earlier today in the UK. I am however impressed. I take it this benefits from a period of burn in too?

Wish I had more of a range for the volume pot - not getting past 9 o clock with the Focal Utopia lol. This thing is powerful.


----------



## RONJA MESCO

Wiljen said:


> The Ta-20 and the Ta-03s are both really good amps for the price and can be made even better with the right tubes.  I'm not sure why they have not gotten the traction that some others have.  I think they are every bit the amp that the little dots, or dark voices are, and nip at the heels of some of the bigger more costly brands.


I have a Xduoo TA-03s incoming.... I am looking forward to rolling some new tubes for this.


----------



## XeNoNF50

LOVE how the TA-30 sounds with the Utopia. Really feels like a good match and has me satisfied for the foreseeable  Hopefully it lasts, I've had a couple of blown fuses since I received it, seemingly same as everyone who has reviewed it so far.


----------



## Wiljen

I've tried the 500mA fuse in place of the stock 250mA to see if it made any difference and it doesn't prevent the problem (may take a bit longer but still does it).  Odd thing for me is it only  blows them if the amp is powered off and plugged in.  It can be on for weeks straight and won't blow the fuse, but powered off, it takes about 10 minutes to guarantee it will blow it.   Some form of leak in a cap onto the mains I'd guess, but still working on finding it.


----------



## XeNoNF50

Yeah seems totally fine when powered on. The fuse seems to survive if it's off for a while then I turn it on. Two of the times I've turned it off then turned it on in quick succession it blew. I don't really plan on turning it off - with lockdown I am using it every day for long periods anyway.


----------



## Wiljen

Ok - News on Ta-30 fuse issue - IT IS RESOLVED!!!!

The factory is now shipping Ta-30s with a 750ma Fuse rather than the 250ma in the early batch and this does resolve the fusing issue entirely.  I've been able to run a 630mA ceramic in mine without blowing a fuse since putting it in (going on 2 weeks).

If you have an early Ta-30 - this is the fuse you need.  https://www.amazon.com/Compstudio-F0-75AL250V-F0-75AL-Cartridge-Fast-Acting/dp/B078NB957P


----------



## Wiljen

I have confirmed that both Lowes and Home Depot stock this fuse as well.  Both carry the Cooper Bussmann brand and the part # BP/GMA-750MA


----------



## XeNoNF50

So any 0.75A 250V fuse should work? 

Thanks for your persistence on finding this information! I really like this amp so I kept it despite the fuse issue. Good to know it's easily resolvable myself.


----------



## Wiljen

XeNoNF50 said:


> So any 0.75A 250V fuse should work?
> 
> Thanks for your persistence on finding this information! I really like this amp so I kept it despite the fuse issue. Good to know it's easily resolvable myself.



To my knowledge, any 5x20mm 0.75A should cure the issue.


----------



## Currawong

Going to write up a review as well here, but in the mean time...


----------



## XeNoNF50

Currawong said:


> Going to write up a review as well here, but in the mean time...




Great review. As an owner of the TA-30 I cannot disagree with much of this. I do really like what it does to the sound signature of the Utopia but I do agree with you that perhaps it comes at a small loss of detail vs alternatives.

I would say that the introduction of a good external DAC makes a difference not only on a sound quality front but also for quality of life due to the high gain rendering usable range of the volume dial quite useless


----------



## Wiljen

I've been pairing the Ta-30 to the new Topping D90MQa and really liking the combo and to @XeNoNF50 comment, using the pre-amp volume control on the D90 allows you to bring the gain down on the Ta-30 to the point you have more usable volume control on the Ta-30 itself.   That and a couple of tube upgrades and you have one heckuva amp for the $.


----------



## dpump

I was under the impression that the 12AU7 tubes are preamp tubes only and that the TA-30 has a solid state output amplifier. Never heard of 12AU7 being used for power amplification, much less the amount of power the TA-30 has. Am I missing something here? I think xDuoo calls them preamp tubes but I don't remember any mention of how output power is handled.


----------



## Wiljen

dpump said:


> I was under the impression that the 12AU7 tubes are preamp tubes only and that the TA-30 has a solid state output amplifier. Never heard of 12AU7 being used for power amplification, much less the amount of power the TA-30 has. Am I missing something here? I think xDuoo calls them preamp tubes but I don't remember any mention of how output power is handled.



12au7 is a pre-amp tube in the bulk of the Xduoo line-up.   Some models (Ta-03s) have tube output stage while other (TA-30, Ta-20,  etc) have a solid state output stage.


----------



## Wiljen

looks like a new one is coming out -  Ta-10R pictures have started to surface - don't have details yet.


----------



## dpump

Wiljen said:


> 12au7 is a pre-amp tube in the bulk of the Xduoo line-up.   Some models (Ta-03s) have tube output stage while other (TA-30, Ta-20,  etc) have a solid state output stage.


Currawong stated in his review that the 12AU7s were the output tubes. That's why I was questioning if that was true. He needs to correct that point in his review so as not to confuse those who have limited knowledge about tube equipment.


----------



## Wiljen

dpump said:


> Currawong stated in his review that the 12AU7s were the output tubes. That's why I was questioning if that was true. He needs to correct that point in his review so as not to confuse those who have limited knowledge about tube equipment.



Agreed, with nearly 4 watts of output power, there simply is no way any of the 12a_7 series could muster that.


----------



## Currawong

I should have mentioned it was a hybrid, my bad.  This is the kind of mistake I make as a result of not scripting my videos.


----------



## Wiljen

Currawong said:


> I should have mentioned it was a hybrid, my bad.  This is the kind of mistake I make as a result of not scripting my videos.




No worries, we've all goofed a time or two, it happens, you clean it up and go on.  I know I've made more than a few mistakes along the way.


----------



## Wiljen

Wiljen said:


> looks like a new one is coming out -  Ta-10R pictures have started to surface - don't have details yet.


Been told I have one on the way so I feel another tube rolling experiment coming on.


----------



## ryanmhz (Jul 1, 2020)

Hi, newbie here.

Im really interested with Xduoo TA-05, but there's no mention regarding if it can be use  as pre out to active speaker, and there are two sets of rca in the backside. I really need the  headphone hybrid amp that  also can be use as pre out. My other option is SMSL SP100 but it dont have enough power to drive R70X. In case someone own the TA-05, mind to share the experience and also answer my question regarding pre out.

Thank you

*sorry for my bad english


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## Wiljen

ryanmhz said:


> Hi, newbie here.
> 
> Im really interested with Xduoo TA-05, but there's no mention regarding if it can be use  as pre out to active speaker, and there are two sets of rca in the backside. I really need the  headphone hybrid amp that  also can be use as pre out. My other option is SMSL SP100 but it dont have enough power to drive R70X. In case someone own the TA-05, mind to share the experience and also answer my question regarding pre out.
> 
> ...



Both of the sets of RCAs on the back are inputs,  the Ta-05 does not have a pre-out.    To have a pre-out, you need to go to the Ta-10.   For the record  The Ta-20 and Ta-30 also have pre-outs,  The Ta-01b and Ta-03s do not.


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## ryanmhz

Wiljen said:


> Both of the sets of RCAs on the back are inputs,  the Ta-05 does not have a pre-out.    To have a pre-out, you need to go to the Ta-10.   For the record  The Ta-20 and Ta-30 also have pre-outs,  The Ta-01b and Ta-03s do not.


Thank you so much for answering my question, im having a hard time looking for someone that know the pre out thing in 05. 

Im in indonesia and my budget for my desk audio setup only around 250 bucks, in aliexpress i found ta-10 around 250 bucks with discount, i almost pull the trigger on ta-10 but recently i found out tempotec dsd serenade price going down quite a bit in aliexpress its around 100, so i change my option to one serenade and one ta-05, because it will be much more versatile and more option, i can use serenade for gaming or another task that need clear and not too much sound coloration, also some of my cans not work well with tube. TA 05 can be use for my speaker and pleasure listening session. But knowing that 05 doesn't have pre out, i need to change my option(again). 

If you have another recommended tube hybrid that under 150 that have pre out, it'll be much appreciated. 

And also is it okay to using tube amp (TA-10) for gaming? I find it kinda weird, well maybe because i am new in this desk setup, i am mostly into portable audio, but after owning R70x i began loving open ba k headphone, and it only for home use. 

*sorry for my bad english and sorry if its too long


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## Wiljen

ryanmhz said:


> Thank you so much for answering my question, im having a hard time looking for someone that know the pre out thing in 05.
> 
> Im in indonesia and my budget for my desk audio setup only around 250 bucks, in aliexpress i found ta-10 around 250 bucks with discount, i almost pull the trigger on ta-10 but recently i found out tempotec dsd serenade price going down quite a bit in aliexpress its around 100, so i change my option to one serenade and one ta-05, because it will be much more versatile and more option, i can use serenade for gaming or another task that need clear and not too much sound coloration, also some of my cans not work well with tube. TA 05 can be use for my speaker and pleasure listening session. But knowing that 05 doesn't have pre out, i need to change my option(again).
> 
> ...



Well it doesn't exactly fit in an Xduoo thread, but the Little Dot Mk II is probably the closest to what you are after as a tube amp with pre-out at roughly $150.   Not too many options at that price point.


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## XeNoNF50

Need some advice, I am guessing there is something wrong with one of the tubes on my TA-30? One is lit way more than the other.


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## Wiljen

Turn the amp off and let the tubes cool - reverse the tubes in the pre-amp sockets and turn it back on.   See if the problem follows the tube (moves to right) or the socket (stays left).  If you're lucky its a tube problem and you replace it, they are consumables after all.  If the swap reveals a socket problem, that's a warranty issue and it does back to Xduoo to fix.


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## arielext

After a few months with Sylvania tubes in my TA-20 I went back to the Philips tubes I had lying around and I'm impressed with the nuances a pre-amp tube can bring to the sound(stage). Beyerdynamic headphones pair really will with the amp, even the T5p. With the Philips tubes I have no audible hiss.


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## Cat Music

Has anyone had a ta-30 and a Feliks Echo to compare? I am impressed by both of them, but the decision is difficult, I am just looking for the best sound quality, I could choose the Echo knowing that it does not have a built-in dac like the ta-30 but if the sound improves with the Echo then I will not think twice


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## XeNoNF50

Wiljen said:


> Turn the amp off and let the tubes cool - reverse the tubes in the pre-amp sockets and turn it back on.   See if the problem follows the tube (moves to right) or the socket (stays left).  If you're lucky its a tube problem and you replace it, they are consumables after all.  If the swap reveals a socket problem, that's a warranty issue and it does back to Xduoo to fix.



Thanks for the advice. When I swapped them it happened again to the right sided tube so I guess it is the unit that is faulty, not the tube. Luckily I bought it from a seller on Amazon UK and returns period is up to 31st July so returns should be easy enough hopefully.


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## Wiljen

XeNoNF50 said:


> Thanks for the advice. When I swapped them it happened again to the right sided tube so I guess it is the unit that is faulty, not the tube. Luckily I bought it from a seller on Amazon UK and returns period is up to 31st July so returns should be easy enough hopefully.



Sorry to hear that, but hopefully it will get straightened out quickly.


----------



## Vaiet

Just a question out of curiosity. Anybody tried to use TA-30 purely as an amp and pair it with a DAC? I know it's a hybrid design but still wondering how it would act in such a combo


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## XeNoNF50

Vaiet said:


> Just a question out of curiosity. Anybody tried to use TA-30 purely as an amp and pair it with a DAC? I know it's a hybrid design but still wondering how it would act in such a combo


That's exactly how I had it with a Sabaj D5 DAC to  TA-30 to Focal Utopia. Worked well until my TA-30 went faulty.


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## Wiljen

Vaiet said:


> Just a question out of curiosity. Anybody tried to use TA-30 purely as an amp and pair it with a DAC? I know it's a hybrid design but still wondering how it would act in such a combo



Yep, I've had it paired to a Burson Swing, a topping D90, and a E30 just playing a bit.


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## Ultrainferno

In today's review we take a close look at the TA-30 and it gets a spot on our recommended buy list.
https://www.headfonia.com/xduoo-ta-30-review/


----------



## Tex Irie

Not sure if the thread is dormant...The TA-20 is my first tube amp and I'm blown away with the sweetness of the sound.   Has anyone compared the TA-20 to the Cavalli Liquid Platinum? I would really love to know if one is "better" than the other in terms of Soundstage, clarity, detail retrieval, musicality (PRaT) , coloration (slight warmth).


----------



## Wiljen

Tex Irie said:


> Not sure if the thread is dormant...The TA-20 is my first tube amp and I'm blown away with the sweetness of the sound.   Has anyone compared the TA-20 to the Cavalli Liquid Platinum? I would really love to know if one is "better" than the other in terms of Soundstage, clarity, detail retrieval, musicality (PRaT) , coloration (slight warmth).




I have had both and think they are within the margin of error of each other and easily can leap frog each other depending on other components and which tubes are in use.  The TA-20 is a great budget amp, You should be well served by it.  The next step up is probably going to take $1000 or more investment to really improve the sound quality notably.


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## soas

I've always wondered how it compares to something like the Bottlehead Crack which gets heaps of praise. That's something that punches way above its weight, helped by the fact that assembly costs are offset.

Hopefully I will get a chance to try out different tube amps to not only hear the differences, but also to find out if they're even for me or not.


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## Wiljen

I've had a crack floating around for years and what you will find is it is as good as the build materials, the quality of the build, and the quality of the tubes used in it.  If you do get one, get the speedball for sure and plan on spending about $200 on tubes to really get the best out of it.  It is at that point, that $1000 amp I was speaking of.


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## Tex Irie

Wiljen said:


> I have had both and think they are within the margin of error of each other and easily can leap frog each other depending on other components and which tubes are in use.  The TA-20 is a great budget amp, You should be well served by it.  The next step up is probably going to take $1000 or more investment to really improve the sound quality notably.



Any recommendations at the $1000 price range that work well with low impedance headphones and IEMs? Specifically the headphones and IEMs listed in my signature.


----------



## Tex Irie

Wiljen said:


> I've had a crack floating around for years and what you will find is it is as good as the build materials, the quality of the build, and the quality of the tubes used in it.  If you do get one, get the speedball for sure and plan on spending about $200 on tubes to really get the best out of it.  It is at that point, that $1000 amp I was speaking of.


Also which tubes did you use? I'll do the research on its sonic characteristics to see if it works with my setup.


----------



## Wiljen

Tex Irie said:


> Also which tubes did you use? I'll do the research on its sonic characteristics to see if it works with my setup.



Bendix 6080wb (about $150)  and a pair of Brimar Black plate / Red Logo 12au7s (these are now about $100 each, they were closer to $50 when I bought my stash several years back). .


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## Wiljen

Tex Irie said:


> Any recommendations at the $1000 price range that work well with low impedance headphones and IEMs? Specifically the headphones and IEMs listed in my signature.



At 1K, I'd look at Woo audio Fireflies, Feliks Audio Expressivo, the Little Dot MKViii (8), and the Xduoo Ta-30 (its that good).  

If you can stretch to $1300, the Woo Audio Wa2 should be on your short list of things to try, also in that price bracket the Feliks Audio Elise should be one to audition.  If you can find a used Auris Euterpe, it should be in the 1000-1300 range and is a great dac/amp as well.  

There are also a lot of Chinese models like the Yaqin series of amps that can be made fantastic but usually require a bit of DIY to get there.  Mine for example needed a new stepped attenuater (read volume knob) and to be recapped from one end to the other.  After those updates, it sounds fantastic, but it was a $749 amp to start with and work on it and tubes has very likely doubled that (I haven't done the math but the volume control alone was $235)  so really not much of a savings compared to something like the Feliks that starts with the upgrades already installed.


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## Garak (Aug 10, 2020)

Wiljen said:


> The next step up is probably going to take $1000 or more investment to really improve the sound quality notably.



Never mind, looks like you just beat me to it with the above post lol.


----------



## Tex Irie

Wiljen said:


> At 1K, I'd look at Woo audio Fireflies, Feliks Audio Expressivo, the Little Dot MKViii (8), and the Xduoo Ta-30 (its that good).
> 
> If you can stretch to $1300, the Woo Audio Wa2 should be on your short list of things to try, also in that price bracket the Feliks Audio Elise should be one to audition.  If you can find a used Auris Euterpe, it should be in the 1000-1300 range and is a great dac/amp as well.
> 
> There are also a lot of Chinese models like the Yaqin series of amps that can be made fantastic but usually require a bit of DIY to get there.  Mine for example needed a new stepped attenuater (read volume knob) and to be recapped from one end to the other.  After those updates, it sounds fantastic, but it was a $749 amp to start with and work on it and tubes has very likely doubled that (I haven't done the math but the volume control alone was $235)  so really not much of a savings compared to something like the Feliks that starts with the upgrades already installed.


Dude thank you for this treasure trove of information.


----------



## chillysalsa

Wiljen said:


> ...There are also a lot of Chinese models like the Yaqin series of amps that can be made fantastic but usually require a bit of DIY to get there.  Mine for example needed a new stepped attenuater (read volume knob) and to be recapped from one end to the other.  ...



Is there a Yaqin dedicated headphone amp? I see just integrated with a front headphone jack. My friend has the 103 integrated, he said it was pretty good but did have some quality issues.


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## Wiljen

chillysalsa said:


> Is there a Yaqin dedicated headphone amp? I see just integrated with a front headphone jack. My friend has the 103 integrated, he said it was pretty good but did have some quality issues.



Yes, there have been a couple different Yaqin headphone models.  Mine is an MS-34D (now discontinued I believe).  The current one is the PH-5L if memory serves.


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## chillysalsa (Aug 11, 2020)

Wiljen said:


> Yes, there have been a couple different Yaqin headphone models.  ... The current one is the PH-5L if memory serves.


I see, looks similar to the MS-23b phono preamp I used to have. Don't know how well the little pre tubes will drive stuff.


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## Cat Music

Wiljen said:


> At 1K, I'd look at Woo audio Fireflies, Feliks Audio Expressivo, the Little Dot MKViii (8), and the Xduoo Ta-30 (its that good).
> 
> If you can stretch to $1300, the Woo Audio Wa2 should be on your short list of things to try, also in that price bracket the Feliks Audio Elise should be one to audition.  If you can find a used Auris Euterpe, it should be in the 1000-1300 range and is a great dac/amp as well.
> 
> There are also a lot of Chinese models like the Yaqin series of amps that can be made fantastic but usually require a bit of DIY to get there.  Mine for example needed a new stepped attenuater (read volume knob) and to be recapped from one end to the other.  After those updates, it sounds fantastic, but it was a $749 amp to start with and work on it and tubes has very likely doubled that (I haven't done the math but the volume control alone was $235)  so really not much of a savings compared to something like the Feliks that starts with the upgrades already installed.


I am interested in a Feliks Echo, do I need to upgrade the tubes in that amp?


----------



## Wiljen

chillysalsa said:


> I see, looks similar to the MS-23b phono preamp I used to have. Don't know how well the little pre tubes will drive stuff.


me either as I haven't had a chance to play with one to date.  Maybe someday when things calm down again.


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## Wiljen

Cat Music said:


> I am interested in a Feliks Echo, do I need to upgrade the tubes in that amp?



No, you shouldn't have to upgrade tubes for it as there really are not very many options for it.  Both the 6N6P and 6N1P used in the Echo are true Soviet designs without a direct western counterpart.   The 6N1P was made in 5 different Russian facilities ( Svetlana, Reflector, Ulyanov, Voskhod, and Novosibirsk) at some point with both Svetlana and Reflector still producing them.  Likewise the 6N6P was made in most of those same plants and may have been made Ryazan as well.  This gives you some options to try out different tubes in the Echo if you decide to, but in my experience they are all close enough that having a spare set or two may be all your really need.  These are the same tubes used in the Schiit Valhalla as well so you may want to look at it as an option as they come up on the used market with fair regularity inexpensively.  Also many will say 6N1P is equal to 6922 - not true as the true 6N1P draws twice the heater current and if a circuit is designed for the 6N1P it may well destroy a 6922.


----------



## Cat Music

Wiljen said:


> No, you shouldn't have to upgrade tubes for it as there really are not very many options for it.  Both the 6N6P and 6N1P used in the Echo are true Soviet designs without a direct western counterpart.   The 6N1P was made in 5 different Russian facilities ( Svetlana, Reflector, Ulyanov, Voskhod, and Novosibirsk) at some point with both Svetlana and Reflector still producing them.  Likewise the 6N6P was made in most of those same plants and may have been made Ryazan as well.  This gives you some options to try out different tubes in the Echo if you decide to, but in my experience they are all close enough that having a spare set or two may be all your really need.  These are the same tubes used in the Schiit Valhalla as well so you may want to look at it as an option as they come up on the used market with fair regularity inexpensively.  Also many will say 6N1P is equal to 6922 - not true as the true 6N1P draws twice the heater current and if a circuit is designed for the 6N1P it may well destroy a 6922.


Thank you, I was unaware of that information. Now, I know you have the TA-30, but I don't know if you tried the Feliks Audio as my question is: which of the two will give me the best amplification in sound quality? I know the TA-30 has a built-in dac, quite the opposite, the Echo needs a Dac, but if we look for differences between the two amps in terms of sound quality, who will be the winner? Taking into account that the TA-30 was not made any update, that is, working with the tubes that come by default.


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## Wiljen

Cat Music said:


> Thank you, I was unaware of that information. Now, I know you have the TA-30, but I don't know if you tried the Feliks Audio as my question is: which of the two will give me the best amplification in sound quality? I know the TA-30 has a built-in dac, quite the opposite, the Echo needs a Dac, but if we look for differences between the two amps in terms of sound quality, who will be the winner? Taking into account that the TA-30 was not made any update, that is, working with the tubes that come by default.



There is no clear answer between the two.  The Echo is more comparable power wise to the Ta-03s or Ta-10 while the Ta-30 is a brute and actually more potent than even the Elise in the Feliks line-up.  what headphone are you planning on pairing this with?


----------



## Cat Music

Wiljen said:


> There is no clear answer between the two.  The Echo is more comparable power wise to the Ta-03s or Ta-10 while the Ta-30 is a brute and actually more potent than even the Elise in the Feliks line-up.  what headphone are you planning on pairing this with?


Sorry, I think I should have clarified that information, I currently have a Sendy Aiva, it is a magnetic plane, do you think it would be a good martch with either of the two amplifiers? If I go for the Echo I thought I would pair it with a D90 or Ares II


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## Wiljen

Cat Music said:


> Sorry, I think I should have clarified that information, I currently have a Sendy Aiva, it is a magnetic plane, do you think it would be a good martch with either of the two amplifiers? If I go for the Echo I thought I would pair it with a D90 or Ares II



The Avia requires a little power to drive well, but nothing insane so should do just fine with the Echo or something like the Valhalla.   The Ta-30 is overkill as I use mine with things like the He-560 and He-6 that are known for being about as sensitive as a brick.


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## Cat Music

Wiljen said:


> The Avia requires a little power to drive well, but nothing insane so should do just fine with the Echo or something like the Valhalla.   The Ta-30 is overkill as I use mine with things like the He-560 and He-6 that are known for being about as sensitive as a brick.


Thank you!! What you mention is about the proper power to drive the Aiva. What about the sound quality? which is the favorite?


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## Wiljen

Cat Music said:


> Thank you!! What you mention is about the proper power to drive the Aiva. What about the sound quality? which is the favorite?



I think the Feliks should do well with the Avia, the Ta-30 will have very little usable volume control before it is too loud to be usable so while SQ is probably about equal, the Echo is a much more realistic purchase.   As for Echo vs Schiit Valhalla2 - they are for all realistic use cases identical in both power and sound quality.   Buy the one you like the look of better or the one you can get for the least expense.


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## Wiljen

Got the 2nd round XP-2 (the pro) coming soon for review.  Be interesting to see how much more they packed in that tiny box.


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## cleg

My video about TA-30, it's great for full-size headphones


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## S Crowther

Are we expecting a new model to replace the TA-20?


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## Wiljen

S Crowther said:


> Are we expecting a new model to replace the TA-20?



Yes,  A ta-20 revamp is in the works as is a middle ground between Ta-20 and Ta-30.   Watch for the Ta-26.


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## arielext (Sep 18, 2020)

Source:  xDuoo TA26 - SLaudio - TAI NGHE VIỆT (taingheviet.com)
Not convinced yet it's the real deal though ...


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## S Crowther

arielext said:


> Source:  xDuoo TA26 - SLaudio - TAI NGHE VIỆT (taingheviet.com)
> Not convinced yet it's the real deal though ...


I hope not. It looks like it is SE only. The 2 things I like about the TA-20 design are that it is fully balanced and is amp only, no DAC.


----------



## dpump

The TA-26 looks to be a Bottlehead Crack style amp with a 6SN7 driver tube and a 6AS7 output tube. I hope it is a real product as that tube configuration is one of my favorites.


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## lycos

dpump said:


> The TA-26 looks to be a Bottlehead Crack style amp with a 6SN7 driver tube and a 6AS7 output tube.



I think you mean Darkvoice?
Crack uses 12au7 for driver.


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## cleg

xDuoo TD-30 text review​
English: https://porta.fi/dac-and-tube-amp-xduoo-ta-30-review-synthesis-of-times/
Russian: https://porta.fi/ru/obzor-czap-i-lampovogo-usilitelya-xduoo-ta-30-sintez-vremyon/


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## Wiljen

getting excited to see the Ta-20r and Ta-26 soon


----------



## r343

Does TA-20 rca Output tune signal with tubes or is it just passtrough?


----------



## BadgerRivFan

r343 said:


> Does TA-20 rca Output tune signal with tubes or is it just passtrough?


The output signal from the TA-20 is the same, whether single-ended or balanced.  The power output is different, but there is no "passthrough" of the signal if you are using the RCA vs. XLR output.


----------



## smoothb0re

Does anyone here have tube recommendations specifically for the TA-20 in the $40-60/pair range? It's damn difficult to decide what to get - there are a million options and I have no idea what's overpriced and what isn't. All I'm looking for is a safe bet that is neutral or warm-ish with decent bass, detail and stage. Nothing special, just an upgrade from the stock tubes.

I'd really love to hear your opinions. My TA-20 is on the way here and I hope to get tubes for it before xmas - I've been hearing that upgrading the tubes is a must.


----------



## Wiljen

smoothb0re said:


> Does anyone here have tube recommendations specifically for the TA-20 in the $40-60/pair range? It's damn difficult to decide what to get - there are a million options and I have no idea what's overpriced and what isn't. All I'm looking for is a safe bet that is neutral or warm-ish with decent bass, detail and stage. Nothing special, just an upgrade from the stock tubes.
> 
> I'd really love to hear your opinions. My TA-20 is on the way here and I hope to get tubes for it before xmas - I've been hearing that upgrading the tubes is a must.



I wrote an article specifically on tube rolling the Ta-20 - it has several good options in that price range depending on what your preferences are.
https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/


----------



## smoothb0re

Wiljen said:


> I wrote an article specifically on tube rolling the Ta-20 - it has several good options in that price range depending on what your preferences are.
> https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/



I actually read that article before, very well written. My issue still is that when searching for a tube, I get a million results with prices ranging from cheap to stupid, and I don't get what the difference is, and I have zero clue if I'm being ripped off.

I just now found that being EU based is a massive issue, seems that 90% of sellers are either in Asia or the US.


----------



## Wiljen

smoothb0re said:


> I actually read that article before, very well written. My issue still is that when searching for a tube, I get a million results with prices ranging from cheap to stupid, and I don't get what the difference is, and I have zero clue if I'm being ripped off.
> 
> I just now found that being EU based is a massive issue, seems that 90% of sellers are either in Asia or the US.



Ok, let me save you a little time then, start with a pair of 12au7 RCA Blackplates.  As long as they are matched reasonably, any of the RCA from the blackplate era should be solid performers without costing a ton and you don't have to worry about 1 year models or finding a specific type.


----------



## smoothb0re

Wiljen said:


> Ok, let me save you a little time then, start with a pair of 12au7 RCA Blackplates.  As long as they are matched reasonably, any of the RCA from the blackplate era should be solid performers without costing a ton and you don't have to worry about 1 year models or finding a specific type.


Thanks! 

I went ahead and got a pair of the black plates, and another pair of RCA 12au7 clear top, side getter, rib plate ones per another recommendation. It cost me a little bit more than what I had planned to because of expensive shipping, but I wanted to have atleast two good options to choose from. 

I appreciate the clear and concise advice! I'll let you know how they sound once the tubes, amp and headphones arrive.


----------



## Galapac

Apos Audio now selling the TA-10R
Apologies if this was posted previously.

https://apos.audio/products/xduoo-t...jb20iLCAia2xfY29tcGFueV9pZCI6ICJMZGs4U1cifQ==


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## 23jim

Looks very interesting with the new Dac I wonder if the soundstage will widen?


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## smoothb0re (Dec 12, 2020)

Not a fan of the red exterior, would like to see a black and/or silver alternative.

My TA-20 arrived a few days back and thus far I'm impressed. The aftermarket tubes haven't arrived yet, but even with stock tubes the amp sounds fantastic. My HE5XX hasn't arrived yet either, but I've been running Ollo S4's on the amp and it sounds great. There's just one major problem, an audible hiss on the left channel. The hiss persists no matter the volume or source used. Hopefully it's just a bad quality Chinese tube and can be fixed when the aftermarket tubes arrive later this month. I was also unable to check the 4-pin XLR output as I only have one balanced cable and it's for the HE5XX.


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## smoothb0re

I don't know how I didn't think of this in the first place, but I switched the tubes around and the hiss went from left channel to right, so it appears to be a tube issue while the amp should be ok. That's a relief, I really like the sound of the amp. Now I'll just have to wait for the aftermarket tubes to arrive to be sure.


----------



## BubbaJay

Just ordered the xDuoo TA-20 tube amp along with a set of JJ ECC802s to replace the cheap stock ones.  This will be only my second tube amp with the Schiit Vali being the only other I've had, though I've had both the original Vali and the second one so I guess this will be number 3 then.  Really looking forward to hearing how my Arya and AP2000ti sound with it since they're my most neutral and bright headphones but I think the Z1R will also sound good even though it's a warmer headphone, at least I hope it does.


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## smoothb0re (Dec 16, 2020)

BubbaJay said:


> Just ordered the xDuoo TA-20 tube amp along with a set of JJ ECC802s to replace the cheap stock ones.  This will be only my second tube amp with the Schiit Vali being the only other I've had, though I've had both the original Vali and the second one so I guess this will be number 3 then.  Really looking forward to hearing how my Arya and AP2000ti sound with it since they're my most neutral and bright headphones but I think the Z1R will also sound good even though it's a warmer headphone, at least I hope it does.



Let us know how the JJ ECC802s sound on it!

Both of the RCA tubes I ordered have arrived in the country, and should be in my post office by Friday, so I'll be able to get some impressions in during the weekend. Unfortunately I still only have the Ollo S4 loaner pair on hand to test with - my HE5XX is still on the way and probably won't be here before Christmas. (They arrived in Germany late last week, but still haven't even moved on from Frankfurt. Might take until January before they are in Finland. Not happy with drop.com's shipping options).

Gotta say, I really miss my Aeolus, HEXv2 and LCD-2C. I think all three would have absolutely LOVED this amp. No use crying over spilled milk though - at least selling those headphones literally helped save a life.

It's an incredible achievement for the asking price from Xduoo - it's not a surprise they had to go for cheap Chinese tubes when the price is so low and quality otherwise is so high. Impressive.


----------



## S Crowther

smoothb0re said:


> Let us know how the JJ ECC802s sound on it!
> 
> Both of the RCA tubes I ordered have arrived in the country, and should be in my post office by Friday, so I'll be able to get some impressions in during the weekend. Unfortunately I still only have the Ollo S4 loaner pair on hand to test with - my HE5XX is still on the way and probably won't be here before Christmas. (They arrived in Germany late last week, but still haven't even moved on from Frankfurt. Might take until January before they are in Finland. Not happy with drop.com's shipping options).
> 
> ...


The headphone that really does benefit from this amp is the Sennheiser HD800s.


----------



## Sound Eq

Tex Irie said:


> Any recommendations at the $1000 price range that work well with low impedance headphones and IEMs? Specifically the headphones and IEMs listed in my signature.


i have an auris euterpe for sale, if interested

https://www.head-fi.org/threads/auris-euterpe.945925/


----------



## smoothb0re

I have still yet to receive my HE5XX (Thanks, DHL eCommerce - 3+ weeks to get from Frankfurt to Speyer, that's like 100km? Wonder how long until it actually gets to FIN... Would have been nice to have them for the holidays, being stuck alone at home trying to avoid getting covid which would be a death sentence.), but even on the S4 loaner the TA-20 with the RCA 5963 black plates is absolutely fantastic. It's shocking how much the stock tubes hold this amp back. I've never heard such a big difference with a tube change before, so I was caught quite off guard. With a sub $30 tube investment it manages to largely compete with amps that cost twice as much, or more. To be honest, it's shockingly good - great slam and tight bass, much wider soundstage, and a slight injection of tube warmth and euphoria to the mids were my initial thoughts.

Next it'll be time to test the RCA cleartop side getter rib plates, and see how they differ from the 5963's. Exciting stuff, I can definitely see how people can get lost in this rabbit hole! More than anything, it'll be so nice to have proper audio gear once the 5XX arrive, after having been forced to sell everything I own - partly due to covid, partly due to my and a family member's health failing. I was lucky to be able to afford getting the 5XX and TA-20 thanks to sharing the cost with a friend. I realise I won't be able to afford anything like an Aeolus, HEXv2 or LCD-2c ever again, but at least I have the ability to enjoy some decent audio in the years I have left. It's nice that fairly good audio can be had for not a ton of money now, though I will always miss the aforementioned three, my all-time favourites.


----------



## smoothb0re

So far the TA-20 with RCA 5963 black plates seems to be a perfect match to the HE5XX. The combination definitely punches way above its price - my first impression was that I was listening to $1000 planars on a high-end amp.

I've found the HE5XX to be quite amp dependent - depending on the amp they can be anything from borderline endgame to mediocre. Even just changing the tubes on the TA-20 to RCA 12au7 cleartop side d getters had a pretty significant effect on the sound, and not a great one - though it was still better than any other amp I tried them on. On Vincent KHV-111 tube hybrid, Parasound Zdac's headphone amp, Schiit Magni, JDS O2 & Atom, drop 789, and SMSL SP200 the 5XX wasn't great. Only on the TA-20 and Topping NX4DSD the headphones really came alive. Huge recommendation to any 5XX owners - get a TA-20 with decent tubes.


----------



## arBalsekar

Seems like I want to buy xduoo TA-20 for my Hifiman Ananda, but I can't try it before buying. Did anyone listened to this combination? I'm curious if there is any hiss / background noise?


----------



## Dolores Dolomites (Jan 31, 2021)

smoothb0re said:


> Huge recommendation to any 5XX owners - get a TA-20 with decent tubes.


Hello everyone!
Sow-uh... I've only just slipped into the rabbithole along with the bloody apneademic so I'm by no means experienced yet, especially on tube amplifiers!
I've got the TA-20 on sale on BF because I wanted to start digging tube sound, but I really don't know where to start from with so many tubes to choose from...

What I'm looking for over the stock ones is a better S/N ratio - because yes, @arBalsekar, the amp has a relevant noise floor - a more spacious soundstage and good bass slam that the Massdrop x Sennheiser HD6XX which would love.
Not all of the previous feats need to be achieved together of course... There's probably tubes which benefit one over the other.
A little advice to get me oriented would be lovely, and thanks in advance!

Edit: Couple of important things I forgot to ask... Where do you suggest to shop for tubes in the EU?
How much would you suggest to get matched pairs for the extra cost?


----------



## CJG888

Before 31. December, I would have said Langrex...

Tube Amp Doctor here in Germany are also a reliable source.


----------



## Dolores Dolomites

CJG888 said:


> Tube Amp Doctor here in Germany are also a reliable source.


Thanks a lot for your advice! I had an eye on that shop already after googling around... Looks great !


----------



## smoothb0re

I just went on ebay with the recommendations I got from this thread, and the Schiit Lyr 3 tube rollers thread, and found two great pairs for less than 100€ overall. Especially the RCA 5963 black plates are absolutely amazing. 

As for noise, I had an audible hiss with stock tubes but that was easily solved with aftermarket tubes. I can't recommend tube rolling enough - the stock chinese tubes really hold the TA-20 back.


----------



## BubbaJay

I got my JJ and Mullard tubes for my TA-20 and they both sound better than the stock tubes but I don't hear too much of a difference between them.  The Mullard tubes might sound just a touch cleaner and the JJ's are a little warmer but the difference is very small.  I'm thinking of getting these GE tubes I've heard are very good but I'm going to wait for a while so I can really get the feel for these after I've put more hours on them.


----------



## Dolores Dolomites (Jan 10, 2021)

Thank You for all the useful information, Gentlemen!
Very happy with the TA-20 and Senn HD6XX even with the stock tubes, provides warmth and added 'stage with little to no detail loss. Awesome!


----------



## BubbaJay (Jan 12, 2021)

I just had my TA-20 go into protect mode with that little red light flashing.  I thought it had something to do with my cables because I was changing them and after I turned it back on it happened but it turns out it was the tubes that went out, either one which is what I'm guessing or maybe both.  As soon as I switched them out it was all good but I only had the tubes for a little over a week and that sucks because I really enjoyed how they sounded, but the 2 Mullard's I have in now sounds good as well.  I was planning on getting a few more eventually but I guess I'll go ahead and do it sooner.

It's been a few hours and I ended up seeing a review for some NOS GE military stock 12AU7 for sale that seems to be really good and I sure hope so at $100 for 2.  The Mullard's I'm using now does sound very nice and I'm hoping the GE tubes sound even better.  Tube rolling is a lot of fun because you can get subtle changes to the signature from tube to tube and I love that.


----------



## Dolores Dolomites

BubbaJay said:


> It's been a few hours and I ended up seeing a review for some NOS GE military stock 12AU7 for sale that seems to be really good and I sure hope so at $100 for 2. The Mullard's I'm using now does sound very nice and I'm hoping the GE tubes sound even better. Tube rolling is a lot of fun because you can get subtle changes to the signature from tube to tube and I love that.


Really sorry for your tube(s) passing away this soon, Bubba!
Sucks big time indeed.

I'm really enjoying the way my TA-20 sounds even with stock tubes on high-impedance 'phones (from FLAC > thru HQPlayer > M200...), but went on pulled the trigger on a pair of matched '50s RCA blackplates and some other... er... rather random 12au7's that tickled me, landing next week on my porch.
* Baby Rollin' *
Can't wait to fully understand that fun of experincing different sound imprints you mentioned... And hoping to keep this thread alive with impressions.
Unless I missed others taking this one over, that is.  =)


----------



## Shakmal

I have never used any tube amp before and would really appreciate for any expert opinion here if the the newly released XDUOO MT-602 can be a good tube pre-amp...
https://www.xduoo.net/product/mt-602/


----------



## kvad

arBalsekar said:


> Seems like I want to buy xduoo TA-20 for my Hifiman Ananda, but I can't try it before buying. Did anyone listened to this combination? I'm curious if there is any hiss / background noise?



I've been using the Ananda with the TA-20 and a pair of Philips NOS tubes. Sounds sublime. When I first got the Ananda I demoed it in the store on an Ayon tube amp which sounded marvelous. Got them home and didn't sound as good on the amps I had. Was a bit light at the bottom, and a bit too much energy up top for my taste. All that is good now though. More weight and the top has been reigned in a bit without loosing the airiness and subtle details.


----------



## jlspa182

Could someone give me their opinion on how xduoo ta 20 works with a fostex th900 or a ZMF Atticus? 
Thanks


----------



## HTSkywalker

kvad said:


> I've been using the Ananda with the TA-20 and a pair of Philips NOS tubes. Sounds sublime. When I first got the Ananda I demoed it in the store on an Ayon tube amp which sounded marvelous. Got them home and didn't sound as good on the amps I had. Was a bit light at the bottom, and a bit too much energy up top for my taste. All that is good now though. More weight and the top has been reigned in a bit without loosing the airiness and subtle details.


Am considering a Hybrid amp as well for my Ananda and both the Cavalli CTH and TA-20 are on my radar, any ideas about the CTH mating ? maybe you tried it before deciding on TA-20 ? are you using balanced input and output ?


----------



## cdf294 (Feb 2, 2021)

I purchased a used TA-20 some time ago and every time I think about upgrading to a different amp, I question why I need an upgrade.
The TA-20 has been one of the most enjoyable inexpensive purchases I've made in this hobby in a long time and I don't feel that it does a disservice to my planars in any way.


----------



## cdf294 (Feb 3, 2021)

Not that anyone has asked but I've tried quite a few pairs of vintage and new tubes in this amp and found that my preferred tube thus far has been the triple mica black plate CRP 5814A Raytheon. I only mention this because I scored the matched pair for $40 but I've also seen them selling for well over that cost.
The easiest solution is to pick up a matched pair of late 50's Baldwin (yellow label) black plate Raytheons for around $30 and call it good. IMO, newly manufactured tubes for the same money can't touch them.

Of course I suppose it's possible that I could prefer something other than the Raytheons if I were using a different set of headphones.


----------



## HTSkywalker

Anyone have an experience about the TA-20 compared to the Cavalli CTH ?


----------



## HTSkywalker (Feb 5, 2021)

arBalsekar said:


> Seems like I want to buy xduoo TA-20 for my Hifiman Ananda, but I can't try it before buying. Did anyone listened to this combination? I'm curious if there is any hiss / background noise?


I read a lot about the TA-20 and the Cavalli CTH and possible mating with the Ananda (which I have along with Focal Elear) and ended up ordering the CTH, will update you on the mating once received, please update me if you were able to try the TA-20 Ananda combination.


----------



## smoothb0re

cdf294 said:


> I purchased a used TA-20 some time ago and every time I think about upgrading to a different amp, I question why I need an upgrade.
> The TA-20 has been one of the most enjoyable inexpensive purchases I've made in this hobby in a long time and I don't feel that it does a disservice to my planars in any way.



Agreed - especially with proper tubes the TA-20 punches way above its price bracket. I mean I'd even say I see no reason to "upgrade" to a Liquid Plat, as I don't think it's much better sound-wise. That's remarkable for a 300€ amp - even if the tubes were an additional 50-100€ it's still cheap for the performance you get. How on earth did Xduoo manage that?


----------



## cdf294

I decided to do a little tube rolling on the TA-20 tonight since something unexpected happened that will result in some tube swapping in the near future.
I don't know if it is a good or bad thing but I stumbled into 3 pairs of tested Raytheons for $30 shipped- 2 pair of black plates and a pair of gray plates. I figure this means that I will pretty much be using Raytheons for the life of this amp, not that I am complaining if they sound anything like the 2 pair of Raytheons that I already have. In addition to the 5814, I also have a pair of Baldwin labeled black plates so I would think the 2 pair of black plates should be very similar although they will have halo getters instead of the square getters on the Baldwins. It's the gray plates that I am really wondering about since I already know I like black plates. For the price, I just couldn't walk away.

For a change of pace, I plugged in some 1950's lightning logo Sylvania black plates that will stay installed until the tubes I purchased today show up early next week.


----------



## kvad

HTSkywalker said:


> Am considering a Hybrid amp as well for my Ananda and both the Cavalli CTH and TA-20 are on my radar, any ideas about the CTH mating ? maybe you tried it before deciding on TA-20 ? are you using balanced input and output ?



Completely missed your question, sorry about that. I see in the meantime you went for the CTH, don't have any experience with that one.

I've been using the TA-20 with balanced output to the Ananda. It in turn is fed by a Musician Pegasus DAC via the record out of a Rega Elex-R (driving speakers) using regular RCA cables. I'll test with XLR cables directly from the DAC one of these days.


----------



## HTSkywalker

kvad said:


> Completely missed your question, sorry about that. I see in the meantime you went for the CTH, don't have any experience with that one.
> 
> I've been using the TA-20 with balanced output to the Ananda. It in turn is fed by a Musician Pegasus DAC via the record out of a Rega Elex-R (driving speakers) using regular RCA cables. I'll test with XLR cables directly from the DAC one of these days.


And how about your impressions about that combination ?


----------



## synfinatic

I'm using some socket savers in my TA-20 so 3D printed some risers for the guards.






On a side note, I discovered the ground wire in the case which mounts to the PCB was not tight.  The bolt holding it was too long for the hole.  Ended up cutting the screw shorter so I could have a solid ground connection.

Anyways, I'm still looking for tubes I like.  The stock tubes are way to sterile and flat for me.  I tried some RCA clear tops, but with my LCD-2C's it makes the music painful to listen to and gives me a headache after 5-10 minutes.  The feeling I get is when you listen to podcaster who doesn't know what they're doing and doesn't use a pop filter.

Currently have some Mullards in which are better than the other two.


----------



## kvad

HTSkywalker said:


> And how about your impressions about that combination ?



The Pegasus came before the TA-20/Ananda replacing a Chord Mojo. Tested the Mojo and Pegasus head to head with the Rega Elex-R driving a pair of Guru Junior speakers. It was a substantial improvement. Previously it had been slightly harsh, sometimes a bit fatiguing. That went away, while also feeling more detailed and adding a better sense of space. Right out of the box the Pegasus was very impressive, but had too much energy in the high frequencies. Thankfully that calmed down after about a day of use.


----------



## Wiljen (Feb 8, 2021)

MT-601 and 602 arrived in my collection about a week ago now.  Working on getting reviews finished and some of the tube rolling started but the spoiler is both are worth an audition.   Both are hybrid with the 601 using a 6922 followed by a pair of IRF630N mosfets while the 602 uses a pair of 6ak5 ahead of a quad of D882M BJT for power amplification.     The 601 is somewhat limited on output power so best used with 150 Ω  or so over-ears or iems.    The 602 has better than 1 watt output power and handles most of my stuff with ease.    Not too bad for a couple of Sub-$100 models.


----------



## HTSkywalker

Wiljen said:


> MT-601 and 602 arrived in my collection about a week ago now.  Working on getting reviews finished and some of the tube rolling started but the spoiler is both are worth an audition.   Both are hybrid with the 601 using a 6922 followed by a pair of IRF630N mosfets while the 602 uses a pair of 6ak5 ahead of a quad of D882M BJT for power amplification.     The 601 is somewhat limited on output power so best used with 150 Ω  or so over-ears or iems.    The 602 has better than 1 watt output power and handles most of my stuff with ease.    Not too bad for a couple of Sub-$100 models.


Was thinking of using the 602 as a pre-amp but probably the stock tubes should be upgraded adding an $80


----------



## Wiljen

HTSkywalker said:


> Was thinking of using the 602 as a pre-amp but probably the stock tubes should be upgraded adding an $80



Yep, I like your thinking and with a pair of JAN Sylvania 5654's it sings.


----------



## FyxeHexyz

Wiljen said:


> MT-601 and 602 arrived in my collection about a week ago now.  Working on getting reviews finished and some of the tube rolling started but the spoiler is both are worth an audition.   Both are hybrid with the 601 using a 6922 followed by a pair of IRF630N mosfets while the 602 uses a pair of 6ak5 ahead of a quad of D882M BJT for power amplification.     The 601 is somewhat limited on output power so best used with 150 Ω  or so over-ears or iems.    The 602 has better than 1 watt output power and handles most of my stuff with ease.    Not too bad for a couple of Sub-$100 models.


Looking forward to a review and the tube-rolling series with these bois  I just got my 602 today and I'm already loving it (my first tube amp, or even hybrid in the first place). 
Do you have any starting tube recommendation? I love the original tube so far but I'm looking for something that has slightly more sub-bass and soundstage


----------



## HTSkywalker

FyxeHexyz said:


> Looking forward to a review and the tube-rolling series with these bois  I just got my 602 today and I'm already loving it (my first tube amp, or even hybrid in the first place).
> Do you have any starting tube recommendation? I love the original tube so far but I'm looking for something that has slightly more sub-bass and soundstage


yeah let us know about your impressions, are you using it as an amp or pre-amp ? did you try with planars ?


----------



## FyxeHexyz (Feb 9, 2021)

HTSkywalker said:


> yeah let us know about your impressions, are you using it as an amp or pre-amp ? did you try with planars ?


I'm unsure as to how to describe it 🤣 but I'll try anyways.

I paired mine with the XD-05+ running as the DAC. Used Acoustune HS1695ti iem and Hifiman Sundara. There is a channel imbalance area near the bottom with right side being louder, I think it is around... 7 - 8 o'clock (the first bar from minimum)

The lows are there but it's only "enough"... At least for me. It's really clean though but it won't be a good kick. I call it a clean bass since it doesn't linger long. 

Mids are warm-ish and very clear 🤔 

The highs are there and it doesn't hurt my ears at least but it sparkles.

All in all.... It sounds like a balanced solid-state with refined highs and lows with more body to it. Although at times it can be thin-ish but accurate though 🤔 reminded me of the stock XD-05+ but with a larger soundstage, better imaging and clarity, less sub-bass, refined highs, good warmth in the mids n lows. Typical XDuoo house sound if you've listened to most of their stuff.

P.S. Definitely worth it for a $100 and could be endgame for most people who just wanted something simple n good. My 6J1 toobs haven't reached the 50 hours proper warm up yet but the lows n mids definitely is getting thicker and kicking more 🤣

P.S.S. Any slightly warmer toobs recommendation? I love the 6j1 sound but I want it to be slight warm-ish. 🤣 I'm used to the XD-05+ with Burson V5i


----------



## HTSkywalker

FyxeHexyz said:


> I'm unsure as to how to describe it 🤣 but I'll try anyways.
> 
> I paired mine with the XD-05+ running as the DAC. Used Acoustune HS1695ti iem and Hifiman Sundara. There is a channel imbalance area near the bottom with right side being louder, I think it is around... 7 - 8 o'clock (the first bar from minimum)
> 
> ...


nice and thorough analysis  but yet I got even more lost lol
did it have enough juice to run the Sundara to its full potential ? did you use the balanced ports ? I was checking on the TA-20, probably it's a much lesser amp.


----------



## FyxeHexyz

HTSkywalker said:


> nice and thorough analysis  but yet I got even more lost lol
> did it have enough juice to run the Sundara to its full potential ? did you use the balanced ports ? I was checking on the TA-20, probably it's a much lesser amp.


haha ikr. I got lost in the middle of explaining it myself. Audio is really hard to describe XD

To answer your question I'd say... yes  definitely yes. It's already loud around 10 - 11 o'clock. Balanced port? This guy doesn't have one I think. It has RCA and Aux in only. I'm currently using the aux in

oh and to add onto that, these two sounded like a wayyy better, warmer and cleaner XDuoo X20 DAP if you ever tried it. XDuoo have similar sound on all of its stuff XD


----------



## HTSkywalker

FyxeHexyz said:


> haha ikr. I got lost in the middle of explaining it myself. Audio is really hard to describe XD
> 
> To answer your question I'd say... yes  definitely yes. It's already loud around 10 - 11 o'clock. Balanced port? This guy doesn't have one I think. It has RCA and Aux in only. I'm currently using the aux in
> 
> oh and to add onto that, these two sounded like a wayyy better, warmer and cleaner XDuoo X20 DAP if you ever tried it. XDuoo have similar sound on all of its stuff XD


Got lost with the balanced LOXJIE P20 , probably it make sense to buy it and use it only with its stock tubes not to pay more. As I understood from you, the stock tubes are not that bad ?


----------



## FyxeHexyz (Feb 10, 2021)

HTSkywalker said:


> Got lost with the balanced LOXJIE P20 , probably it make sense to buy it and use it only with its stock tubes not to pay more. As I understood from you, the stock tubes are not that bad ?


To my ears, definitely not bad at all 🤣 it's quite balanced in my opinion. If you prefer warmer then get another tube. If you prefer more analytical and bright... Why the hell are you buying a hybrid tube amp to begin with? 🤣🤣🤣🤣

Eagerly waiting for audiofool tube roll review. I'm looking for a very slightly warmer tube XD too warm and it'll sound like the burson v5i lol


----------



## Wiljen

Western Electric 403b or Sylvania or GE 5654 are both a step up.   I have some early Sylvania blue tipped (aircraft grade) JHS 6AK5s that are particularly good in it with a much more 3d stage.


----------



## CJG888

Or the Mullard equivalent...


----------



## SrTexugo

Today the xduoo mt-602 arrived. The amp is beautiful, well finished, wonderful sound and with an output power of 1.3w. But ... I found the sound very similar to the Fiio k5 Pro that I have here. I expected it to be noticeably different, because of the tubes. Anyway, I only tested it for a few hours ... Maybe with a few days the differences will become clearer.


----------



## CJG888

Pan Am on the cheap?


----------



## CJG888

Without the DAC, of course ...


----------



## HTSkywalker

Received the CTH today and tried it a bit with both the Ananda and Elear.
Definitely it kicks way higher than its price with a very clean warm sound out of the box.
Sound should develop more after break in.


----------



## dsrk

HTSkywalker said:


> Received the CTH today and tried it a bit with both the Ananda and Elear.
> Definitely it kicks way higher than its price with a very clean warm sound out of the box.
> Sound should develop more after break in.


Hi,
Is it Alex Cavalli Tube Hybrid? How is it compared to Xduoo-TA20?


----------



## HTSkywalker

dsrk said:


> Hi,
> Is it Alex Cavalli Tube Hybrid? How is it compared to Xduoo-TA20?


Yes it is the Cavalli tube hybrid but i don’t have the TA-20. Regardless it’s a wonderful amp.


----------



## RONJA MESCO

Any one on here have the TA-03s? I am itching to tube roll again...any good suggestions?


----------



## Glokta

I have a TA-20 (3 months old) together with 3 different pairs of tubes (Mullard, Sylvania and Jan GE) for sale on ebay if someone's interested,  but only for UK.


----------



## FyxeHexyz

RONJA MESCO said:


> Any one on here have the TA-03s? I am itching to tube roll again...any good suggestions?


@Wiljen have written these~ you can refer to em 
Tube Rolling the Xduoo Ta-03s tube amplifier (12au7 and 6S19P). | Audiofool Reviews 

P.S. I'm sure my MT-602 has fully matured now. I'm actually loving the sound of the 6j1 ngl. It has a nice balance of being super clear and slightly warm. It curbs those sharp trebles down while staying sparkly at some songs. I feel the imaging and separation are all super good. Soundstage is wide but not deep for sure but they ain't super close. It has a nice distance to it. The sub-bass is a little weak though but it's there (pretty sure it's not my iem or headphone since I've heard these two give a good kick). I don't think I will tube roll for now since I can't find any good seller nearby my area (shipping is a pain right now since my wallet is dried). 

Used with Acoustune HS1695ti (In-Ear Monitor) and Hifiman Sundara (Open-Back Headphone).


----------



## HTSkywalker

Glokta said:


> I have a TA-20 (3 months old) together with 3 different pairs of tubes (Mullard, Sylvania and Jan GE) for sale on ebay if someone's interested,  but only for UK.


Would definitely be interested to know the reason why you are selling it 😊


----------



## Glokta

HTSkywalker said:


> Would definitely be interested to know the reason why you are selling it 😊



To be fair for me it's all about the journey, tinkering and testing with tubes, amps, headphones, finding things that punch above their weight, etc, but when your wife starts lookin' at you funny seeing 12 headphones on a shelf and 4-5 amps, 3 DACs... I started tiding up about two months ago and kept 4 headphones, a couple of IEM's and I'll get down to one amp probably.

Just to let you guys know, it has already been bought.


----------



## HTSkywalker

Glokta said:


> To be fair for me it's all about the journey, tinkering and testing with tubes, amps, headphones, finding things that punch above their weight, etc, but when your wife starts lookin' at you funny seeing 12 headphones on a shelf and 4-5 amps, 3 DACs... I started tiding up about two months ago and kept 4 headphones, a couple of IEM's and I'll get down to one amp probably.
> 
> Just to let you guys know, it has already been bought.


I know the funny look especially when you express ship with DHL from the US "tubes" which does not probably get well appreciated by females 🤣🤣


----------



## Dolores Dolomites

Glokta said:


> To be fair for me it's all about the journey, tinkering and testing with tubes, amps, headphones, finding things that punch above their weight, etc, but when your wife starts lookin' at you funny seeing 12 headphones on a shelf and 4-5 amps, 3 DACs... I started tiding up about two months ago and kept 4 headphones, a couple of IEM's and I'll get down to one amp probably.
> 
> Just to let you guys know, it has already been bought.


Ha! Totally agreed... It is really all about the journey.
And the looks... Oh yes. Since I have no wife (or girlfriend) and no profitable job these days, I've been giving _myself_ some funny looks and decided to settle with what I have for a while.

The TA-20 sounds as sweet as it's clearly getting nowhere else than on my wooden bedside pedestal, especially after I went for some aftermarket tubes pairs.
I've got a pair of Russian Tung-Sol 12AU7W / 6189 on right now. Exquisite result.
There're a couple of pairs I like even better though: the Sylvania/Philips USA 6189 have a bigger stage and warmer bass.
But nothing beats my absolute faves... The RCA 3-MICA Blackplates (D-getter) from the 50s. Bwuoys, they're absolutely amazing!
Pricey most of the times when you find 'em, but if anyone is out to buy one pair only - if you ask me - that would be IT. Jaw-dropping, holographic soundstage along with detail and tube goodness across the whole frequency spectrum. 💕 Saving those for the "special occasions". =)

I'm very glad to read about gentlemen are also having a great time with the new compact hybrid amps as well as with the TA-20 like I am.
I guess that xDuoo knows how to deal with the matter while making these toys accessible at the same time!  Bravo! 👏


----------



## Glokta

Oh yeah, I forgot, let me share my experience with the tubes that I've tried:
Mullard - great midrange, good bass, smooth and rich
Sylvania - detailed, high-end extension, high resolution
Jan GE - excellent definition, stunningly quiet, very good layering, a greater sense or realism


----------



## spookyshan

What’s the general consensus on the TA-30? neutral/warm amp? I’ve been pretty intrigued about possibly pairing this with dt1990.


----------



## tkddans

I ordered the TA-30 from Drop. Should be here in 1.5 months or so.

Any recommendations on tubes to roll? I already ordered a pair of Mullard 12AU7 after reading one person's recommendation earlier in the thread.


----------



## dpump

Why order the TA-30 from Drop when Apos Audio will match the Drop price, give you a 2-year warranty, and you will have it in less than 2 weeks?


----------



## tkddans

dpump said:


> Why order the TA-30 from Drop when Apos Audio will match the Drop price, give you a 2-year warranty, and you will have it in less than 2 weeks?


Because Drop is selling it for $525 right now (instead of $710). I also have $200 of Drop dollars to spend, and the purchase gives me $45 back in more drop dollars.

So my net cost is $280 instead of $710. Pretty big reason, for my case anyway.

Even without Drop dollars, it’s still nearly $200 discounted there for anyone right now.


----------



## Galapac

You could have used your Drop dollars on something else but it’s your $$$ and I get using your Drop points is like a rewards card redemption.

What @dpump was stating is that Apos would match the $525.00 price, get it shipped immediately, and give you a 2 year warranty.
Drop is offering no warranty with this purchase so you only have the 30 day return window.

I think of that $45 dollars as the warranty cost and piece of mind. The Apos team are great in my experience anyway.
Not having that warranty gave me pause on this Drop purchase.

https://drop.com/buy/xduoo-ta-30-tube-dac-amp/talk/2764698


----------



## tkddans (Feb 27, 2021)

Galapac said:


> You could have used your Drop dollars on something else but it’s your $$$ and I get using your Drop points is like a rewards card redemption.
> 
> What @dpump was stating is that Apos would match the $525.00 price, get it shipped immediately, and give you a 2 year warranty.
> Drop is offering no warranty with this purchase so you only have the 30 day return window.
> ...


Totally good point! I forgot about price matching.

But ya, that $200 I have....not sure what else I would use it on other than an item I’m looking to buy right now. I don’t expect to buy too much more on drop right now too, so I figure this is a good opportunity. I just happened to be looking for tube amps at an affordable price, and boom.

EDIT:: And I guess in terms of the scenario of me not liking the amp, I can sell it in the worst case scenario.


----------



## Galapac

tkddans said:


> Totally good point! I forgot about price matching.
> 
> But ya, that $200 I have....not sure what else I would use it on other than an item I’m looking to buy right now. I don’t expect to buy too much more on drop right now too, so I figure this is a good opportunity. I just happened to be looking for tube amps at an affordable price, and boom.
> 
> EDIT:: And I guess in terms of the scenario of me not liking the amp, I can sell it in the worst case scenario.


BTW...here is a good article on tube rolling the TA-30.... https://audiofool.reviews/tube-rolling-the-xduoo-ta-30/


----------



## tkddans

Galapac said:


> BTW...here is a good article on tube rolling the TA-30.... https://audiofool.reviews/tube-rolling-the-xduoo-ta-30/


Yea! That's the one I used to buy a pair. I got the top pic on his list. Any other recommendations for this amp or for tubes in general?


----------



## andred

Galapac said:


> BTW...here is a good article on tube rolling the TA-30.... https://audiofool.reviews/tube-rolling-the-xduoo-ta-30/


thanks for the audiofool article.   just got my ta-30 from a head-fi listing.  first impressions are that its good. i was hoping that the TA-30 took the strengths of the TA-20 (detail, imaging, openness etc) and added more heft and bottom.  it does those things - but sort of obscures the strengths of the TA-20.  imho.  so far.  without much tube rolling (other than to get the stock tubes out asap).  

looking for others' impressions of TA-20 vs TA-30 too.


----------



## tkddans

andred said:


> thanks for the audiofool article.   just got my ta-30 from a head-fi listing.  first impressions are that its good. i was hoping that the TA-30 took the strengths of the TA-20 (detail, imaging, openness etc) and added more heft and bottom.  it does those things - but sort of obscures the strengths of the TA-20.  imho.  so far.  without much tube rolling (other than to get the stock tubes out asap).
> 
> looking for others' impressions of TA-20 vs TA-30 too.


Interesting.

What do you feel the TA-20 did well that the 30 obscures?


----------



## andred

tkddans said:


> Interesting.
> 
> What do you feel the TA-20 did well that the 30 obscures?


the "bigger" sound of the TA-30 seems to fill in some of the "space" i perceive with the TA-20.    "thicker" and less "open" than the TA-20.   this is an "initial impression" at this point.  i've just ordered the rectifier tubes for the TA-30 that were recommended in the audiofool TA-30 tube rolling review and will make a more careful analysis after they arrive.


----------



## andred

cdf294 said:


> I decided to do a little tube rolling on the TA-20 tonight since something unexpected happened that will result in some tube swapping in the near future.
> I don't know if it is a good or bad thing but I stumbled into 3 pairs of tested Raytheons for $30 shipped- 2 pair of black plates and a pair of gray plates. I figure this means that I will pretty much be using Raytheons for the life of this amp, not that I am complaining if they sound anything like the 2 pair of Raytheons that I already have. In addition to the 5814, I also have a pair of Baldwin labeled black plates so I would think the 2 pair of black plates should be very similar although they will have halo getters instead of the square getters on the Baldwins. It's the gray plates that I am really wondering about since I already know I like black plates. For the price, I just couldn't walk away.
> 
> For a change of pace, I plugged in some 1950's lightning logo Sylvania black plates that will stay installed until the tubes I purchased today show up early next week.


impressions from the various tubes in your TA-20?  i'm about to embark on tube rolling in mine.  thanks


----------



## HTSkywalker

Anyone compared the TA-20 to Darkvoice 336SE ?


----------



## andred

cdf294 said:


> I purchased a used TA-20 some time ago and every time I think about upgrading to a different amp, I question why I need an upgrade.
> The TA-20 has been one of the most enjoyable inexpensive purchases I've made in this hobby in a long time and I don't feel that it does a disservice to my planars in any way.


+1 on the TA-20 being a bargain tube amp.  esp. if can find a used one.


----------



## andred

new to this thread.  sorry for the barrage.  i'm interested in any tubes to roll into the TA-20 to add or enhance bass weight.  thanks.


----------



## S Crowther

Any sign of an update/replacement for the TA-20?


----------



## S Crowther (Mar 4, 2021)

andred said:


> new to this thread.  sorry for the barrage.  i'm interested in any tubes to roll into the TA-20 to add or enhance bass weight.  thanks.


This may help:
High Resolution / Clear Detailed / High-End Extension:
12AU7A RCA clear top
ECC82=12AU7 Siemens
5184A Siemens long plates & triple mica 12AU7 Telefunken ribbed plate
12AU7 Tungsol
12AU7A Sylvania

Warm / Smooth / Rich:
7316 Amperex Holland or Philips Miniwatt Holland 1959-1963
12AU7 RCA Black Plates 1950's (very rich and creamy)
12AU7 Mullard (great midrange, good bass)
12AU7 Ediswan by Brimar (quiet, detailed, smooth, nice)
12AU7 Brimar 1960's
CV4003 Brimar (very relaxed, quiet, balanced)

Lively 3D Mid-range / Good Bass Mid-range Vocals More Pronounced Sweet Highs:
12AU7 Amperex Bugle Boy Holland
12AU7 Philips Holland
12AU7 Philips Miniwatt Holland

Detailed / Articulate / Warm:
12AU7 Mullard long plates 1950's-60's (best mids, best tonality, best with vocals and instruments)
CV4003 Mullard Box Plates 1960's
12AU7 Telefunken smooth plates
12AU7 GE early 1960's


----------



## InstantSilence

Whxih xduoo tube amp can power lcd4z? Trying to get started into tubes to see what it's about. 
But its a 17ohm (I think) planar that while it's marketed as easy to drive, it's actually quite demanding. 
 Any xduoo amp up to task?


----------



## HTSkywalker

InstantSilence said:


> Whxih xduoo tube amp can power lcd4z? Trying to get started into tubes to see what it's about.
> But its a 17ohm (I think) planar that while it's marketed as easy to drive, it's actually quite demanding.
> Any xduoo amp up to task?


The TA-20 gives good results with the 25 Ohms Ananda, should be fine as the TA-20 is a hybrid


----------



## InstantSilence

HTSkywalker said:


> The TA-20 gives good results with the 25 Ohms Ananda, should be fine as the TA-20 is a hybrid


Does this mean it doesn't get as *tubey* as full tube amps?  Does the hybrid mess with it? 

Looking for a super smooth, laid back listen.


----------



## HTSkywalker

InstantSilence said:


> Does this mean it doesn't get as *tubey* as full tube amps?  Does the hybrid mess with it?
> 
> Looking for a super smooth, laid back listen.


There is no Hybrid that can give more than 20% tube sound as the power amp is an SS while the pre-amp is tube driven but they have the advantage of driving planars. The Cavalli CTH is a laid back warm sounding amp.
If you want the full experience get an OTL but forget about the planar on it.


----------



## InstantSilence

HTSkywalker said:


> There is no Hybrid that can give more than 20% tube sound as the power amp is an SS while the pre-amp is tube driven but they have the advantage of driving planars. The Cavalli CTH is a laid back warm sounding amp.
> If you want the full experience get an OTL but forget about the planar on it.


Oh daddy! Don't say that... Deceive me! 
I need to keep the planar... There can't be an otl for Meh plannar 

Maybe one day... 
Know of any hybrid that has the most tubey sound?


----------



## HTSkywalker

InstantSilence said:


> Oh daddy! Don't say that... Deceive me!
> I need to keep the planar... There can't be an otl for Meh plannar
> 
> Maybe one day...
> Know of any hybrid that has the most tubey sound?


Darkvoice 330SE


----------



## Galapac

You can keep your planar just don’t expect to use an OTL amp with it that will sound halfway decent with it. The physics just aren’t there for a headphone with that low of an impedance. Buy another set of headphones if you want that warm tubey sound.


----------



## jonathan c (Mar 8, 2021)

InstantSilence said:


> Oh daddy! Don't say that... Deceive me!
> I need to keep the planar... There can't be an otl for Meh plannar
> 
> Maybe one day...
> Know of any hybrid that has the most tubey sound?


Hybrid h/p/a for planar magnetic h/p:  Liquid Platinum with capacitor upgrades and external linear power supply is the _least_ solid-state sounding hybrid h/p/a. When driving my Audeze LCD-X (stated impedance: 20 ohms), the LP is outstanding.


----------



## HTSkywalker

jonathan c said:


> Hybrid h/p/a for planar magnetic h/p:  Liquid Platinum with capacitor upgrades and external linear power supply is the _least_ solid-state sounding hybrid h/p/a. When driving my Audeze LCD-X (stated impedance: 20 ohms), the LP is outstanding.


Agree but the LP with an LPS would be in the $1K category, in this case A Violectric SS V280 is a good choice and it is warm, not tubey warm but as good as it gets and you will the ability to drive any kind of headphone. The LCD-X shines with the V280


----------



## HTSkywalker

Anyone tried the TA-20 with the Focal Elear ?


----------



## HTSkywalker

Anyone tried the TA-20 with the Focal Elear ?


----------



## Barndoor

Does anyone have any impressions of using HD6xx on the MT602?
I have a pile of 6J1 tubes I previously used in a little dot, so this is a tempting cheap little amp for me.


----------



## CJG888

The big question: is the MT-602 better than the LD 1+....

More something for the Grado fans out there.


----------



## Barndoor

CJG888 said:


> The big question: is the MT-602 better than the LD 1+....
> 
> More something for the Grado fans out there.


My LD I+ developed a lot of noise, so I don't use it anymore


----------



## Jonmakauu

Features and balanced capabilities aside, which is better, the TA-20 or the TA-10R? Considering both will have the topping d90 as the source.


----------



## hmscott

Jonmakauu said:


> Features and balanced capabilities aside, which is better, the TA-20 or the TA-10R? Considering both will have the topping d90 as the source.


My preference would be for the fully balanced design of the TA-20, plus I get to use the XLR balanced outputs from the D90 MQA to cut down on the environmental noise passed over an RCA link.

The only benefits I can think of is that the TA-10R is newest, comes in Red!, and only uses 1 12AU7 - which cuts tube rolling costs in half - but then again it's a different market for single tubes vs pairs of matched tubes - I think I get 2 good tubes easier and cheaper, while single tubes are usually the "odd man out" - kinda like the "3rd wheel" tube in triples - 2 tubes match and look great then there's that 3rd tube off enough to not match to either of the pair 

It's a tough call, a small savings in up front cost for the same power output and a single tube --- IDK, some of the expense goes into a DAC I wouldn't use and that's not always a good thing to have a digital device in an analogue amp box...

As always it comes down to listening sessions A/B'ing both with the same Tube(s).

If you get both and test them side by side, please do report back what you heard


----------



## Jonmakauu

hmscott said:


> My preference would be for the fully balanced design of the TA-20, plus I get to use the XLR balanced outputs from the D90 MQA to cut down on the environmental noise passed over an RCA link.
> 
> The only benefits I can think of is that the TA-10R is newest, comes in Red!, and only uses 1 12AU7 - which cuts tube rolling costs in half - but then again it's a different market for single tubes vs pairs of matched tubes - I think I get 2 good tubes easier and cheaper, while single tubes are usually the "odd man out" - kinda like the "3rd wheel" tube in triples - 2 tubes match and look great then there's that 3rd tube off enough to not match to either of the pair
> 
> ...


Yeah you have a point, the built in dac of the ta 10r would just be a waste. I might just get a 2nd hand ta 20


----------



## jonathan c

hmscott said:


> The only benefits I can think of is that the TA-10R is newest, comes in Red!, and only uses 1 12AU7 - which cuts tube rolling costs in half - but then again it's a different market for single tubes vs pairs of matched tubes - I think I get 2 good tubes easier and cheaper, while single tubes are usually the "odd man out" - kinda like the "3rd wheel" tube in triples - 2 tubes match and look great then there's that 3rd tube off enough to not match to either of the pair


If one is looking at “new production” tubes, single tube / pair tube pricing per tube is _almost_ equivalent - there is often a “matching” fee for pairing. With “new old stock” (vintage unused or lightly used) tubes, single tube / pair tube pricing can be vastly different - much higher per tube for pairs, especially for coveted items such as Siemens E288CC.


----------



## hmscott

jonathan c said:


> If one is looking at “new production” tubes, single tube / pair tube pricing per tube is _almost_ equivalent - there is often a “matching” fee for pairing. With “new old stock” (vintage unused or lightly used) tubes, single tube / pair tube pricing can be vastly different - much higher per tube for pairs, especially for coveted items such as Siemens E288CC.


What I was trying to say is it comes down to availability.  To get that pair of tubes for me I have to consider buying a Quad or a Triple in order to get the pair I desire.  If I wanted a single tube, the same consideration might apply, I'd need to buy a pair to get the single tube I desire, or maybe even the same Triple/Quad to get the single tube I need.

The single tubes are often the ones that don't match into a pair, not necessarily worse, but not necessarily better.  And, I've found to get what I want I may need to buy a desirable matched pair put with a 3rd unwanted tube - not matched to the other 2 - simply put there to move it out of inventory.  And, the singles I find are not necessarily desirable, the best tubes are matched into pairs.  I suppose buying a pair to get a single is kinda the same thing 

For new tubes you'd think you could simply buy a single, but the top end China boxed pairs are the best tubes paired off, again you'd need to buy 2 tubes to get one.

Either way, when buying tubes to match an amp with a single tube or a pair, there are similar considerations when buying tubes that may increase the cost beyond the single/dual socket costs expected.


----------



## jonathan c

hmscott said:


> What I was trying to say is it comes down to availability.  To get that pair of tubes for me I have to consider buying a Quad or a Triple in order to get the pair I desire.  If I wanted a single tube, the same consideration might apply, I'd need to buy a pair to get the single tube I desire, or maybe even the same Triple/Quad to get the single tube I need.
> 
> The single tubes are often the ones that don't match into a pair, not necessarily worse, but not necessarily better.  And, I've found to get what I want I may need to buy a desirable matched pair put with a 3rd unwanted tube - not matched to the other 2 - simply put there to move it out of inventory.  And, the singles I find are not necessarily desirable, the best tubes are matched into pairs.  I suppose buying a pair to get a single is kinda the same thing
> 
> ...


Good points. At least with tube headphone amps vs tube speaker power amps, the tubes should last longer making the purchase decision less frequent...unless tube “rolling” is in play...


----------



## hmscott

jonathan c said:


> Good points. At least with tube headphone amps vs tube speaker power amps, the tubes should last longer making the purchase decision less frequent...unless tube “rolling” is in play...


Well, IDK the exact lifespan of these preamplifier tubes, 2000-4000 hours is what I have heard, but then again I've heard some military spec tubes are supposed to go for 10k-20k hours.

Anyone know for sure?  Links?


----------



## John Massaria (Mar 18, 2021)

my quick review on the xDuoo MT-602 - enjoy the music always everyone - a thing that unites us all as a world and planet .... bottom line if everyone owned a sweet sounding tube amp like this I really do believe war and poverty would end...  
https://www.head-fi.org/showcase/xd...eadphone-amplifier.25046/reviews#review-25520


----------



## SoundGuru

I just picked up one of these. Its very powerful. I cant listen to Grados (32 ohm) with it as it gets way too loud. Its good with the HD650 though. Build quality is really nice and it is very quiet. I changed the stock tubes to some GE ones, not sure if its a big difference might change it back to the Chinese ones. Definitely recommended!


----------



## Wiljen

Posted my Xa-10 review today -  https://www.head-fi.org/showcase/xduoo-xa-10.25056/reviews    Full sized images on my blog.   Also posted the MT-601 and 602 tube rolling articles to my blog for those interested


----------



## SrTexugo

Wiljen said:


> Posted my Xa-10 review today -  https://www.head-fi.org/showcase/xduoo-xa-10.25056/reviews Full sized images on my blog. Also posted the MT-601 and 602 tube rolling articles to my blog for those interested


Did you see the audioscience review? What do you think about the objective measurements of the site?
I got a xa-10 and liked it a lot, but I was surprised by the results presented by audioscience...


----------



## Wiljen (Apr 23, 2021)

SrTexugo said:


> Did you see the audioscience review? What do you think about the objective measurements of the site?
> I got a xa-10 and liked it a lot, but I was surprised by the results presented by audioscience...



While I understand that others measure better than the Xa-10, realistically the difference between a 112 dB SNR and a 125 dB SNR is inaudible and even ASR admits that their criticism is not based on listening but on the fact that other devices measure better.    I liken this to buying equipment designed for elite athletes to go play tennis in the park, you may feel better because you have it, but it probably isnt changing your game.

W


----------



## SrTexugo

Wiljen said:


> While I understand that others measure better than the Xa-10, realistically the difference between a 112 dB SNR and a 125 dB SNR is inaudible and even ASR admits that their criticism is not based on listening but on the fact that other devices measure better.    I liken this to buying equipment designed for elite athletes to go play tennis in the park, you may feel better because you have it, but it probably inst changing your game.
> 
> W



Nice! Thanks for your review.


----------



## FyxeHexyz

SoundGuru said:


> I just picked up one of these. Its very powerful. I cant listen to Grados (32 ohm) with it as it gets way too loud. Its good with the HD650 though. Build quality is really nice and it is very quiet. I changed the stock tubes to some GE ones, not sure if its a big difference might change it back to the Chinese ones. Definitely recommended!


*sweats* meanwhile I've been using it with my iem (24 ohm)... Makes me question my ears hahaha


----------



## SoundGuru

I think my system has a louder than average source output from my DAC. I am using a Topping E30 from my laptop so its 2V using the DAC mode. That might be the reason...


----------



## Barndoor

Wiljen said:


> Posted my Xa-10 review today -  https://www.head-fi.org/showcase/xduoo-xa-10.25056/reviews Full sized images on my blog. Also posted the MT-601 and 602 tube rolling articles to my blog for those interested


Can I take it that the Sylvania 6AK5 are your favourite of the tubes you tried in the MT-602?
Have ordered myself an MT-602. Sylvania 6AK5 are the tube that I previously used in my Little dot before it went bad, so was the first I planned to try on the MT-602.


----------



## Wiljen

Barndoor said:


> Can I take it that the Sylvania 6AK5 are your favourite of the tubes you tried in the MT-602?
> Have ordered myself an MT-602. Sylvania 6AK5 are the tube that I previously used in my Little dot before it went bad, so was the first I planned to try on the MT-602.


The early Sylvania (pre-1968) are very good and the Western Electric 403b is also a great option.   I prefer the stage of the 6ak5 while Ngoshawk (who I sent the 602 and tubes) prefers the 403 for its mid-range warmth.


----------



## CJG888

I’ve ordered one of these (MT-602) for my „transportable“ system, to go between a Chord Mojo and my recabled DT250-250s. Have also ordered a pair of 1965 JAN Sylvania 6AK5s. I already have a pair each of the Mullards and the Voskhods.

Would there be any point in upgrading the PSU to an iFi iPower 12V?


----------



## CJG888

I‘m seeing this as a latter-day ALO Pan-Am...😀


----------



## Barndoor (Mar 22, 2021)

CJG888 said:


> I’ve ordered one of these (MT-602) for my „transportable“ system, to go between a Chord Mojo and my recabled DT250-250s. Have also ordered a pair of 1965 JAN Sylvania 6AK5s. I already have a pair each of the Mullards and the Voskhods.
> 
> Would there be any point in upgrading the PSU to an iFi iPower 12V?


I've also thought about the potential of using as transportable. I plan to try it with a battery pack and a 5v to 12v USB cable.


----------



## tkddans (Mar 22, 2021)

Just got the TA-30 in. After trying the stock tubes, which sounded great already for a lusher vocal sound over the THX 789, I replaced them with several after market tubes. See pics!

I'm loving it so far! It really feels on first impression that I have my audio chain completed  I have my neutral playback 789 solid state and my lush pleasant TA-30 tube amp. Even on stock they had a favorable impression (and the stock tubes actually looked better visually, particularly the rectifier). I should've shown a pic of them installed, but they're back in the box now.

Currently installed:
- two Mullard 12AU7 tubes (with socket savers from tubemonger)
- one Jan CHS 5931 rectifier


----------



## Barndoor (Mar 22, 2021)

Had a hunt through my tube box.
Have 5 that are compatible with the MT-602
Sylvania 6HA5
GE 6HA5
Philips JAN 5654W
Voskhod
EI Yugo






Not sure the date of the Sylvania and google didn't help.
Nothing seems to be marked on the Tube that would indicate a date.
I don't know whether the box design would be a rough guide?
One of the flaps on the box has 5Z on it. Don't know if that means anything?


----------



## iFi audio

CJG888 said:


> Would there be any point in upgrading the PSU to an iFi iPower 12V?



If your PSU is a regular noisy wall wart, I'd say it's good to at least give iPower a try. It's far quieter, so you might hear a rather noticeable improvement considering money involved.


----------



## SoundGuru

Getting the 601 to pair with Grado RS2e... I am in Malaysia so its easy to get these amps directly from China.


----------



## CJG888

SoundGuru said:


> Getting the 601 to pair with Grado RS2e... I am in Malaysia so its easy to get these amps directly from China.



Should be interesting.

Try to get hold of a JAN Sylvania 7308. I swear by them...


----------



## SoundGuru

Cool thanks for the tip! It should arrive next week.


----------



## tkddans (Mar 27, 2021)

A positive review I just wrote on Drop’s store page for the TA-30:



For amps, I’ve been using the THX 789 solid state and I’ve tried the Jotunheim 2. And way long ago I used the Darkvoice tube amp (and quickly returned it). After using the 789 most of the time now, and trying a newly bought TA-30, I find myself preferring to use the TA-30 - particularly when switching out the tubes with:

Mullard 12AU7 tubes
Jan CHS 5931 rectifier
Not only do I still retain much of the resolution I would have sought out in the 789, I have gained a greater sense of impact, reverb, decay, and a generally bigger sense of natural presence to my music with the TA-30. At first, I preferred the TA-30 only with my HD800 S, rather than playing the 800 S off of my THX 789, but now I also find myself preferring the Hifiman HE6SE V2 off of the TA-30 (and the HE6SE is notoriously difficult to power)! The TA-30 sometimes needs to be turned to the max for the HE6SE to be loud enough (particularly for classical music), but this tube amp does indeed get loud enough to be very enjoyable. I wouldn’t really want to go any louder actually. And for the rest of the headphones you could possibly plug into the TA-30, all being easier to power than the HE6SE, there is always plenty of headroom left over. Just about the only things I have that I prefer to go back to the THX 789 for may be my Clairvoyance IEM’s, and I could still really enjoy them off the tube amp! I would just recommend socket savers from tube monger if you do this, since they have silicone inside to absorb micro phonics - maybe a must for sensitive earphones/headphones. I got the TA-30 when it was priced at $525 (currently it is $599 at time of writing), and I would totally recommend the product at either price or actually full price. The only other thing I would mention is that I’m running the TA-30 from my Schiit Bifrost DAC. It’s not a world of difference from the already very capable built in DAC inside the TA-30, but I do prefer the sound of the TA-30 when using the Bifrost 2 as my DAC. Oh, and the form factor is actually surprisingly smaller than I imagined. It has a thin profile on the desk and fits nicely next to anything else you may have going on.


----------



## Galapac

tkddans said:


> A positive review I just wrote on Drop’s store page for the TA-30:
> 
> 
> 
> ...


Nice write up! Since the TA-30 has an RCA out, did you try passing that into the 789? That would be a nice experiment to see if you get both the tube sound from the TA-30, with the detail retrieval of the 789. I have used the 789 in the past on its own and it can be a bit cold and neutral, things I don’t necessarily enjoy as I really like the sound that tubes convey on my music. That warm distortion just makes me smile as I can “feel” my music.


----------



## spookyshan

tkddans said:


> A positive review I just wrote on Drop’s store page for the TA-30:
> 
> 
> 
> ...


I am curious since you’ve tried both jot2 and ta-30 with HD800s, do you overall prefer HD800s with TA-30? With the upgraded tubes?


----------



## tkddans (Mar 28, 2021)

spookyshan said:


> I am curious since you’ve tried both jot2 and ta-30 with HD800s, do you overall prefer HD800s with TA-30? With the upgraded tubes?


I preferred the THX 789 over the Jot 2, so that may be something to have in mind if you have a different taste on that comparison to start with.

But then I got the TA-30 and prefer it over the 789 for the 800S. You might think that means I would then have to say I like the TA-30 more than the Jot . And...ya it is true for me.

The Jot 2 didn’t do something to the music in any way that I enjoyed more than what I was already getting from the THX 789. And now the TA-30, with my tubes, is adding a new layer of engagement with my music that I didn’t feel with my memory of the Jot 2 or my A/B comparisons with the 789.

I love the 800S on almost anything, including the 789 or still plenty well on the Jot, but the TA-30 has me smiling with a new sensation I haven’t had with the others. It may be a honeymoon phase, with how nice it feels to me right now, but the experience is different enough to sit well as a companion at the desk.

And honestly....if I had to choose which to keep on my desk and which to sell, then I would feel better about keeping the TA-30 than keeping either the 789 or Jot 2. At least, that’s how I feel in this first week here. Grains of salt please


----------



## CJG888

SoundGuru said:


> Cool thanks for the tip! It should arrive next week.


Also, I would recommend getting some of these heat-resistant O-rings (available on Amazon) to damp any residual microphonic issues with the ECC88 / 7308:


----------



## arar

Is the MT-602 a good pick for someone who's interested in getting a feel on how tubes sound (in general and wrt the rest of their gear)? "Proper" OTL tube amps are pretty pretty pretty expensive, so if the 602 has a "tube-y" sound and can sort of give you some hints of what to realistically expect with better tube amps, the asking price seems like a bargain.


----------



## SoundGuru

The 602 for me is not that typical tube sound that is mellow. This amp sounds more balanced, but a bit smoother and natural, than pure solid state. This amp is low impedance so it is quite different to an OTL amp. I use it with HD650 and this pairs quite nice for me.


----------



## arar

Haha, it's starting to feel like every time I pay attention to one tube amp or the other and ask around, the conclusion is that they don't have "that typical tube sound". But I gotcha. I'll likely get the 602 anyway since it's so cheap and cute and I'm so intrigued, but I'll keep in mind that if I dislike the sound, it's not necessarily representative of how I'd feel about OTL tubes (or vice versa).


----------



## fishda30

Waiting for my mt602 to arrive.what tubes to get and where?😁


----------



## CJG888

NOS Sylvanias are generally a good bet. I bought a pair of these:

https://www.ebay.de/itm/1960s-Vinta...-/124508617288?_trksid=p2349624.m46890.l49286


----------



## Wiljen

The Western electric 403b is also a good choice in the 602.


----------



## CJG888

Is it entirely equivalent to a 6AK5? I know some people use it in the LD 1+.


----------



## Wiljen

CJG888 said:


> Is it entirely equivalent to a 6AK5? I know some people use it in the LD 1+.



Technically speaking the 403a version is the exact match for the 6ak5 as both have 175mA heater current.  The 403b has a lower heater current of 150mA so can be used safely in any socket designed for the 6AK5.   If a circuit were designed for the 403b, putting a 6AK5 might overtax the power supply but with such a small difference in current usually this is well within the margins of the design and I know of no instances where using a 6AK5 in a circuit that originally called for a 403b has caused problems.  

Another thing I have been asked several times now regards use of 6AJ5 in the 6AK5 socket.   These two tubes are electrically identical with the 6AJ5 being optimized for high frequency signals (think radio waves) while the 6AK5 is optimized for lower frequencies (audible frequencies).   It was not entirely uncommon to see radios and early tvs that used one tube or the other for both applications in order to only have to stock a single part.     This does not mean the 6AJ5 will necessarily perform as well as microphonics are not a concern once out of the audible range and these may not have ever been tested for that when built.     Also worth noting, I know of no other tube series in which J and K are interchangable so please do not make that inference.


----------



## SoundGuru (Apr 2, 2021)

Got the 601... Unfortunately for me it's picking up alot of RF noise. I thought it was the tube, but sitting in another part of my condo, and the noise is gone. I am not sure if its WiFi noise or something else? Anybody else had a similar problem?

The noise is there with just the headphones plugged in with no source... very strange

After messing around with unplugging everything in my office.... I think the noise actually reduces quite a bit when music is playing.

This amp is still really powerful for 200 mW, and I need to turn my source to 20/100 in windows to get the volume to 9 o clock. This sound is less in your face and probably a better pair with Grado than the 602.. IMO


----------



## fishda30

Will ge5654 fit and work with the 602?


----------



## CJG888

A 5654 is a 6AK5. However, I wasn’t impressed by the sound of the GEs back in the days when I had a LD Mk 3.


----------



## fishda30

CJG888 said:


> A 5654 is a 6AK5. However, I wasn’t impressed by the sound of the GEs back in the days when I had a LD Mk 3.


Thanks.what tubes do you like?


----------



## fishda30

CJG888 said:


> A 5654 is a 6AK5. However, I wasn’t impressed by the sound of the GEs back in the days when I had a LD Mk 3.


Double post.sorry. not sure what happened.


----------



## CJG888

fishda30 said:


> Thanks.what tubes do you like?


I can’t say anything about the 602 yet, as mine is still stuck in Customs.

As far as the LD Mk.III is concerned, I liked the Mullard CV4010 best. Second best were the Voskhods. Upon recommendation from another forum, I bought a pair of Sylvania NOS from 1965.


----------



## SoundGuru

I took a chance on a Phillips JAN 6922 - for the 601 and its great... it helped to reduce the noise a bit, but it definitely improves the low end (detail & control) and really opens up the soundstage compared to the stock tube. This is definitely an improvement over the stock one. In Malaysia it cost me about 30 USD.. (100 rm).


----------



## CJG888

I have one of those in my “Big Box O’ Tubes”. It sounds good, but, alas, is a little noisy. May not be NOS.


----------



## fishda30

Finally here. Very good build quality i must say. Will play with it tonight.


----------



## CJG888

Mine arrived today too. Tested it briefly with Grado 325is. Sound is not bad at all (with the Sylvania tubes), but the usable range of the volume pot is tiny. I will probably have to swap the volume control...


----------



## CJG888

This gives an idea of scale:


----------



## CJG888

Alas, one of my NOS Sylvanias is slightly microphonic.


----------



## jwong

I ordered an Mt602 a couple weeks ago, but it hasn't even shipped yet. I bought 2 sleeves of 1967 Sylvania JAN 5654s. Not that I needed 10 tubes, but there was a coupon I wanted to use.  I just wish the amp would get here so I could try them out!


----------



## CJG888

I’ll try it with the HD250 tonight.


----------



## fishda30

CJG888 said:


> Mine arrived today too. Tested it briefly with Grado 325is. Sound is not bad at all (with the Sylvania tubes), but the usable range of the volume pot is tiny. I will probably have to swap the volume control...


Is it hard to pull out and replace the tubes?


----------



## fishda30

This amp is powerful. Max that i can go with my sundara is 12oclock.

Not sure if the stock tubes need burn in but i replaced them after listening for a few minutes as i didn't get the tubey sound that i was expecting from them. When i plugged in my ge5654 i noticed a more airy presentation. Sound stage a little wider and bass was more extended. There was a difference i can say. Loving it so far. 

I'm really surprised by how this amp performs. As early as now i can say that this is a keeper. Now where do i get those upgrade tubes from?😁


----------



## CJG888 (Apr 8, 2021)

Not at all! Just remember to pull the tubes straight upward, and don’t “wiggle” them in the bases.


----------



## CJG888

There is definitely a design issue here. This amp needs a gain switch!


----------



## CJG888

I just made a major improvement to the sound. I disconnected the SMPS and replaced it with a 5V Anker power bank and 12V converter cable.

This thing is now an ALO Pan Am on the cheap!


----------



## tkddans

CJG888 said:


> I just made a major improvement to the sound. I disconnected the SMPS and replaced it with a 5V Anker power bank and 12V converter cable.
> 
> This thing is now an ALO Pan Am on the cheap!


Wait why? Does it cause damage to roll or “wiggle” the tubes out? Seems easier that way.


----------



## CJG888

Now to find a way of reducing the gain.


----------



## CJG888

tkddans said:


> Wait why? Does it cause damage to roll or “wiggle” the tubes out? Seems easier that way.


The tube sockets are soldered to a PCB. Wiggling the tubes can work the socket loose.


----------



## tkddans

CJG888 said:


> The tube sockets are soldered to a PCB. Wiggling the tubes can work the socket loose.


Oh not if I’m using socket savers though, ya?


----------



## CJG888

Probably not a bad idea, actually. That way you also have the tubes outside the case. Where can I get septal socket savers?


----------



## CJG888

With PSU upgrade.

Now it’s a portable amp, right?


----------



## tkddans

CJG888 said:


> Probably not a bad idea, actually. That way you also have the tubes outside the case. Where can I get septal socket savers?


I got my 9 pin socket savers from tube monger.

Accessories page showing all socket savers here.


----------



## CJG888

Excellent match for the HD250s.


----------



## CJG888

Portable rig:


----------



## Barndoor

CJG888 said:


> Portable rig:


Still waiting for my 602. Ordered it from Australia hoping to get quicker than from China as was for my birthday. Turns out that they ran out of stock, so would probably have had it quicker from China and cheaper.

My plan is also to try it off a battery pack. How long do you reckon the battery will run it for (what capacity battery is it btw?)


----------



## fishda30

CJG888 said:


> With PSU upgrade.
> 
> Now it’s a portable amp, right?


Were there any changes with the sound?


----------



## CJG888

Blacker background, wider soundstage. Not a dramatic difference, though. There is still a little residual hum, but this is not audible at any level that would be used for listening!


----------



## CJG888

I’ve no idea how clean the 12V converter cable is. Presumably it uses some sort of “voltage doubler”, such as that used in the Chord Mojo.


----------



## hmscott

tkddans said:


> Oh not if I’m using socket savers though, ya?


I tried using socket savers, but the Xduoo TA-20 sockets themselves are too far recessed into the body to reach - when you try to pull a tube out of the socket saver it results in the socket saver getting pulled out along with the tube I was trying to replace...  I couldn't get my fingers in there to hold down the socket saver to pull against it to get the tube out by itself.

I gave up on the socket saver idea, so I go slow and steady with the force to insert, and slowly work out the tube by working it a bit side to side and it pops out without too much fuss.

I've only done maybe 30-50 insertions / removals so far, and I don't detect any loosening of the socket - tubes take about the same force to insert and remove - the ones with clean pins that is.

I tried inserting a tube with "dirty" corrosion, and it wouldn't seat well, so I don't recommend doing that - I'm looking for a stiff brush and some contact/pin cleaner to remove the corrosion before inserting.

The are a lot of Chinese ceramic socket replacements available, and I am very comfortable with soldering - I actually considered soldering in the socket savers - but decided I'd wait till the stock sockets needed replacing.  Something to look forward to


----------



## CJG888

Barndoor said:


> Still waiting for my 602. Ordered it from Australia hoping to get quicker than from China as was for my birthday. Turns out that they ran out of stock, so would probably have had it quicker from China and cheaper.
> 
> My plan is also to try it off a battery pack. How long do you reckon the battery will run it for (what capacity battery is it btw?)


It’s a 20,000mAh battery pack.


----------



## CJG888

The 602 works a treat with Grados (325is in my case). You just need to keep the line input well below line level.


----------



## fishda30 (Apr 11, 2021)

Ge5654 brings out the vocals of the 602s. It's very good for jazz with female vocals.


----------



## KevinS2020

I love the XD05 series


----------



## KevinS2020

Especially because you can Op Amp roll. I like the Burson V5i as my favorite.


----------



## screwdriver

Wondering which amp or amp /dac to get  for the ananda and gl2000


----------



## Wiljen

screwdriver said:


> Wondering which amp or amp /dac to get  for the ananda and gl2000


Ananda is easy enough to drive that pretty much any good amp should work.  I can't speak to the GL2000 as I haven't tried it yet.


----------



## S Crowther

Any sign of a replacement for the TA-20?


----------



## der luda

By chance I came across the Xduoo TA 10R a few weeks ago, actually not my area at all.
I got it brand new for € 230, I thought nothing could be lost ... I exchanged the standard tube for a NOS Mullard UK.

I've been listening for a few days now, Ibasso SR2, Clear MG, Ananda ... the LCD X is just coming.
I'm not sure, I don't quite get it ... this amp has such a wonderful listening experience, such a stage, so silky fine spatial, that doesn't match the price and the much more expensive amp   

The hardware too ...how does it work??


----------



## screwdriver

der luda said:


> By chance I came across the Xduoo TA 10R a few weeks ago, actually not my area at all.
> I got it brand new for € 230, I thought nothing could be lost ... I exchanged the standard tube for a NOS Mullard UK.
> 
> I've been listening for a few days now, Ibasso SR2, Clear MG, Ananda ... the LCD X is just coming.
> ...


i received my xduoo ta 10R today . i swapped the stock tubes right away with Brimar CV4003 / 12AU7.  im loving this amp with the GL2000 and the Anada , i think its an excellent amp  if 2wpc at 32 ohms is enough for you .


----------



## der luda

TA 10R
Structure, components and cabling, all very valuable and high-quality components.


----------



## Wiljen

tkddans said:


> Just got the TA-30 in. After trying the stock tubes, which sounded great already for a lusher vocal sound over the THX 789, I replaced them with several after market tubes. See pics!
> 
> I'm loving it so far! It really feels on first impression that I have my audio chain completed  I have my neutral playback 789 solid state and my lush pleasant TA-30 tube amp. Even on stock they had a favorable impression (and the stock tubes actually looked better visually, particularly the rectifier). I should've shown a pic of them installed, but they're back in the box now.
> 
> ...


Hope you like warm brandy.    that thing gets hot.


----------



## tkddans

Wiljen said:


> Hope you like warm brandy.    that thing gets hot.


Hah yea it does. I’m more concerned for my electric bill then anything.

But boy does it power everything I throw at it!


----------



## Wiljen

tkddans said:


> Hah yea it does. I’m more concerned for my electric bill then anything.
> 
> But boy does it power everything I throw at it!


Oh yeah,  I've run an He6 on that thing and it runs it swimmingly.  Hard to imagine it would struggle with much of anything based on that.    It definitely is designed for the power hungry.   The trade off is that you need a -10dB pre-amp gain to use it with iems to give me more usable volume and keep it from hissing.


----------



## cleg

My video about MT-602, once again xDuoo managed to deliver a great value for the price asked


----------



## fishda30

Mt602 is amazing with the e30.


----------



## fishda30

Transportable dac amp. 😁


----------



## Ultrainferno

Second article of @Aerosphere this week, and it's all about the XA-10. Feel free to ask him anything about the XA-10

https://www.headfonia.com/xduoo-xa-10-review/


----------



## Wiljen

MT-604 announced - balanced version of the 602 it looks like with independent volume controls per channel.


----------



## CJG888

Just like the old Croft Supermicro preamp…


----------



## Nooborghini

Wiljen said:


> MT-604 announced - balanced version of the 602 it looks like with independent volume controls per channel.


You think we can tube roll these decently?


----------



## Wiljen

Nooborghini said:


> You think we can tube roll these decently?


I intend to get one and find out


----------



## Nooborghini

Wiljen said:


> I intend to get one and find out


Just ordered one today as well. Gonna be exciting how it pairs with my headphones.


----------



## CJG888

Presumably the Sylvanias will work just as well in there…


----------



## Wiljen

I think one of the potentially big advantages to the dual volume controls of the 604 is that you should be able to use less than perfectly matched quads and volume level using a quick test with a mic and then just use a volume control on a pre-amp/dap rather than tinkering with two volume knobs.   Might be a chance to use some of that stash of tubes that weren't quite good enough to use in other things.


----------



## tudedude

XDUOO MT-602, is there any sound difference between the aux-in on the front vs the RCA-in on the back panel?


----------



## fishda30

tudedude said:


> XDUOO MT-602, is there any sound difference between the aux-in on the front vs the RCA-in on the back panel?


There's no difference on mine.


----------



## CJG888

Same here.


----------



## Nooborghini (May 24, 2021)

Just received mine today and this amp is nice. Bit of a hiss but I think  one of my tube is just defective/poor quality, I can hear the microphonics from it.

Can't wait until I roll these. Really impressed for sub $200 CAD hybrid amp.


----------



## Wiljen

Nooborghini said:


> Just received mine today and this amp is nice. Bit of a hiss but I think  one of my tube is just defective/poor quality, I can hear the microphonics from it.
> 
> Can't wait until I roll these. Really impressed for sub $200 CAD hybrid amp.


what headphone are you using with it?   Specs show a fairly potent amp so it may hiss some with high sensitivity iems and do better with high impedance over-ears.


----------



## Nooborghini

Wiljen said:


> what headphone are you using with it?   Specs show a fairly potent amp so it may hiss some with high sensitivity iems and do better with high impedance over-ears.


Currently swapping between my HD800, HD820, Hifiman HE1000 V2.

The hiss has gone away after I reseated my tubes but the microphonics are still there.


----------



## Wiljen

Nooborghini said:


> Currently swapping between my HD800, HD820, Hifiman HE1000 V2.
> 
> The hiss has gone away after I reseated my tubes but the microphonics are still there.



Gotta agree that with at least the Sennheiser models there shouldn't be hiss from sensitivity.   He1000 probably not either but not quite as hard to drive as the 800/820.


----------



## Nooborghini

Yeah after some time, my left channel is having noise, buzzing, and popping sounds. I hope it is just the tubes, will replace the tubes and see if it fixes it from there. Will need to call Xduoo for the query as well.

When it is working, it's amazing lol. As I write this my right channel is also buzzing slightly.


----------



## tudedude

I've been playing with the xduoo mt-602 for a day now and can't really hear any tubey sound. I've tried the stock tubes and Sylvanias. One thing that surprised me was that it seems a hell lot more powerful than the Magni 3 despite the advertised stats. So for at the same price I think this would be the better option.


----------



## Cran

For xDuoo TA-20 owners:
Can I connect my DAC to TA-20 XLR input, and then RCA out to another amp so the TA-20 function as pre-amp?

The description here says so:
https://drop.com/buy/xduoo-ta-20-balanced-headphone-amp#overview
"The TA-20 can also function as a preamplifier through the RCA out"

But a user left comment here:
https://drop.com/buy/xduoo-ta-20-balanced-headphone-amp/talk/2785712?utm_source=linkshare
"The description is incorrect. I have TA20 and it CAN'T function as a preamplifier through the RCA out. This is only signal pass through."


----------



## Qupie

Interested in getting the TA-10R for my Focal clear MG. Have people on here experience with pairing Focals with xDuoo tubes?

Additional bonus question: is there anyone with pro version of the Clears and TA-10R? I am really curious if the red matches somewhat


----------



## Slim1970

Wiljen said:


> MT-604 announced - balanced version of the 602 it looks like with independent volume controls per channel.


I just placed an order for one of these to tryout. What’s the consensus on sound and has anyone tried different tubes yet?


----------



## Wiljen

Slim1970 said:


> I just placed an order for one of these to tryout. What’s the consensus on sound and has anyone tried different tubes yet?



Working on reviewing it now.  I've been using the Tone2pro to control volume and just set both knobs on the 604 to 90%.     It does improve with other tubes but I'm not through with tube rolling it yet so can't say whats best yet.   Early lead goes to the western electric 403a but still have several to go.


----------



## Slim1970

Wiljen said:


> Working on reviewing it now.  I've been using the Tone2pro to control volume and just set both knobs on the 604 to 90%.     It does improve with other tubes but I'm not through with tube rolling it yet so can't say whats best yet.   Early lead goes to the western electric 403a but still have several to go.


Nice, looking forward to reading more about this product before I get it. I know you’re in the process of writing your review, but can you comment on the bass on this amp?


----------



## Wiljen

Slim1970 said:


> Nice, looking forward to reading more about this product before I get it. I know you’re in the process of writing your review, but can you comment on the bass on this amp?


Bass extension is somewhat tube dependent, but it has good impact even with the stock tubes.  I don't think it elevates the bass as it seems to be pretty linear, but it does have enough power so that big hits don't sag it badly when you have 2 or 3 in succession.


----------



## HTSkywalker

Nooborghini said:


> Just received mine today and this amp is nice. Bit of a hiss but I think  one of my tube is just defective/poor quality, I can hear the microphonics from it.
> 
> Can't wait until I roll these. Really impressed for sub $200 CAD hybrid amp.


Looks good in the dark but would definitely benefit from all 4 tubes rolled, how do you like it ?


----------



## Slim1970

Wiljen said:


> Bass extension is somewhat tube dependent, but it has good impact even with the stock tubes.  I don't think it elevates the bass as it seems to be pretty linear, but it does have enough power so that big hits don't sag it badly when you have 2 or 3 in succession.


Thanks, it sounds like the MT-604 is a nice gateway to getting some tube flavor. The specs look decent enough and I can’t wait to give it go. I think it will play nicely with my Utopia’s. We shall see


----------



## tudedude (Jun 6, 2021)

I didn't notice much tube sound from the xduoo so I added a one little bear as a premamp.  Does it sound better? I don't know. Does it sound more tubey? I don't know. Are there more tubes? yes.

Edit: It sounds better with the Xduoo as the preamp. Much more tubey fullness and better lows. However the little bear sounds the best on its own. Just doing this for schits and giggles.


----------



## Cran

tudedude said:


> I didn't notice much tube sound from the xduoo so I added a one little bear as a premamp.  Does it sound better? I don't know. Does it sound more tubey? I don't know. Are there more tubes? yes.
> 
> Edit: It sounds better with the Xduoo as the preamp. Much more tubey fullness and better lows.


Interesting! What’s the model?


----------



## tudedude

Cran said:


> Interesting! What’s the model?


It's the Nobsound Little Bear FU32 (P32) with the Xduoo mt-602. I'm using the Qudelix 5k as a Bluetooth Dac/DSP


----------



## HTSkywalker

tudedude said:


> I didn't notice much tube sound from the xduoo so I added a one little bear as a premamp.  Does it sound better? I don't know. Does it sound more tubey? I don't know. Are there more tubes? yes.
> 
> Edit: It sounds better with the Xduoo as the preamp. Much more tubey fullness and better lows.


Meaning the Xduoo is not impressive in the tubey sense


----------



## HTSkywalker

tudedude said:


> It's the Nobsound Little Bear FU32 (P32) with the Xduoo mt-602. I'm using the Qudelix 5k as a Bluetooth Dac/DSP


Little bear is nice 👍


----------



## Barndoor

I received my MT602 a couple of weeks ago and also had the same reaction that it doesn't sound as tubey as I'd hoped.


----------



## Cran

tudedude said:


> I didn't notice much tube sound from the xduoo so I added a one little bear as a premamp.  Does it sound better? I don't know. Does it sound more tubey? I don't know. Are there more tubes? yes.
> 
> Edit: It sounds better with the Xduoo as the preamp. Much more tubey fullness and better lows.


How can you connect them?


----------



## HTSkywalker

Barndoor said:


> I received my MT602 a couple of weeks ago and also had the same reaction that it doesn't sound as tubey as I'd hoped.


Then it’s useless to me


----------



## HTSkywalker

Cran said:


> How can you connect them?


Not sure the little bear have any balanced connectors so probably using converters


----------



## tudedude

Cran said:


> How can you connect them?


I use an rca to 3.5mm cable to connect the two amps. You can also use the headphone out from the xduoo, so 3.5mm to 3.5mm cable. The little bear only has one input, 3.5mm.


----------



## HTSkywalker

tudedude said:


> I use an rca to 3.5mm cable to connect the two amps. You can also use the headphone out from the xduoo, so 3.5mm to 3.5mm cable. The little bear only has one input, 3.5mm.


Too many connectors, not a good platform to assess the Xduoo


----------



## HTSkywalker

And stock tubes are normally very cheap


----------



## tudedude

Barndoor said:


> I received my MT602 a couple of weeks ago and also had the same reaction that it doesn't sound as tubey as I'd hoped.


Yeah, exactly why I bought the Little Bear. If you don't need a lot of power it's a better budget amp to get the tubey sound.


----------



## HTSkywalker

tudedude said:


> Yeah, exactly why I bought the Little Bear. If you don't need a lot of power it's a better budget amp to get the tubey sound.


Agree


----------



## jsmiller58

Thinking about picking up the TA-10R….  Is there a big difference over a solid state amp?  Other than the 602 I only have solid state amps and want to make sure I will have a different experience versus what I already have.  Thank you in advance!


----------



## chillysalsa

Has anyone compared the TA series amps? I have the TA-03 which I love with the HD800, since it really responds to the 12AU7 tube choice, and picking a nice warm liquidy tube has great synergy. But... I want to possibly drive other lower ohm cans down the road. Are the other TA amps a sidegrade, or sacrifice the tube character optimization?


----------



## HTSkywalker

jsmiller58 said:


> Thinking about picking up the TA-10R….  Is there a big difference over a solid state amp?  Other than the 602 I only have solid state amps and want to make sure I will have a different experience versus what I already have.  Thank you in advance!


If you want a real difference, get a Darkvoice


----------



## seamon

Just want to confirm - If I connect powered speakers to the RCA out of a xDuoo TA-20, will it go through the tube preamp section?
It should but I want to confirm definitively.


----------



## Cran (Jun 7, 2021)

seamon said:


> Just want to confirm - If I connect powered speakers to the RCA out of a xDuoo TA-20, will it go through the tube preamp section?
> It should but I want to confirm definitively.


Some users here say RCA doesn't pass through:


BadgerRivFan said:


> The output signal from the TA-20 is the same, whether single-ended or balanced.  The power output is different, but there is no "passthrough" of the signal if you are using the RCA vs. XLR output.


But users there say the reverse:
https://drop.com/buy/xduoo-ta-20-ba...k/2785712?utm_source=linkshare&referer=EM4X5H
https://drop.com/buy/xduoo-ta-20-ba...k/2627137?utm_source=linkshare&referer=EM4X5H

I am confused.


----------



## seamon

Cran said:


> Some users here say RCA doesn't pass through:
> 
> But users there say the reverse:
> https://drop.com/buy/xduoo-ta-20-ba...k/2785712?utm_source=linkshare&referer=EM4X5H
> ...


Looks like it doesn't pass through the tube section. Sadge


----------



## HTSkywalker

seamon said:


> Looks like it doesn't pass through the tube section. Sadge


You will need to get a definite answer from the manufacturer or check an open amp, some amp like the DV does pass through the tube and some others like the Violectric does not. Normally if the pot can play with the volume of the pre-out it means it does pass through the tube section.


----------



## Slim1970

Got this little beauty today. I'm giving it a go with my new AT WP900's.


----------



## Cran

HTSkywalker said:


> You will need to get a definite answer from the manufacturer or check an open amp, some amp like the DV does pass through the tube and some others like the Violectric does not. Normally if the pot can play with the volume of the pre-out it means it does pass through the tube section.


I asked xduoo, they said no, it can’t function as tube preamp


----------



## Cran

Slim1970 said:


> Got this little beauty today. I'm giving it a go with my new AT WP900's.


Too bad it can’t be a preamp


----------



## Slim1970

Cran said:


> Too bad it can’t be a preamp


I believe it can be used in that manner. You just need a 4mm to whatever dual output you need or you can get a male 4-Pin XLR to whatever dual output you need. Both should work just fine.


----------



## Cran

Slim1970 said:


> I believe it can be used in that manner. You just need a 4mm to whatever dual output you need or you can get a male 4-Pin XLR to whatever dual output you need. Both should work just fine.


Won't it become TA-20 (tube preamp) > TA-20 (SS headamp) > headamp.  Seems something wrong.


----------



## Slim1970

Cran said:


> Won't it become TA-20 (tube preamp) > TA-20 (SS headamp) > headamp.  Seems something wrong.


Isn't the TA-20 also a hybrid amp? Just like the MT-604 you're getting a mixture of two. The benefits of tubes in the preamp section with the benefits of having a solid state output. If you use it as a preamp to feed a power amp or some other source you'll retain the sound quality of the MT-604 in the same manner as using the TA-20. The only difference is the topology of the two amps. So MT-604 won't sound exactly like a TA-20


----------



## FyxeHexyz

I have a question. Newbie here, I'm currently using my iem with the MT-602 + XD-05Plus (as DAC) and I hear a slight microphonic? (electrical-ish kinda sound). I was wondering if I should jump to the TA-10R or XA-10. I do know the XA-10 would be silent with most iem but does the TA-10R have less noise than the MT-602? I really like the sound and soundstage of the 602, it would be a shame to lose that if I switched to the XA-10. I don't use balanced cables so I don't mind about them much. Anyone have tried all three and could give me a little rundown? That would be extremely helpful, thank you so much.


----------



## Wiljen

chillysalsa said:


> Has anyone compared the TA series amps? I have the TA-03 which I love with the HD800, since it really responds to the 12AU7 tube choice, and picking a nice warm liquidy tube has great synergy. But... I want to possibly drive other lower ohm cans down the road. Are the other TA amps a sidegrade, or sacrifice the tube character optimization?



If you want a drive anything tube amp in the Ta series look at the Ta-30.  It has a lot of tube character and reacts to changes in rectifier as well (faster recovery time, less sag etc).    Being a hybrid with an output transformer makes it suitable for planars and other low impedance headphones that don't like OTL designs.


----------



## Wiljen

FyxeHexyz said:


> I have a question. Newbie here, I'm currently using my iem with the MT-602 + XD-05Plus (as DAC) and I hear a slight microphonic? (electrical-ish kinda sound). I was wondering if I should jump to the TA-10R or XA-10. I do know the XA-10 would be silent with most iem but does the TA-10R have less noise than the MT-602? I really like the sound and soundstage of the 602, it would be a shame to lose that if I switched to the XA-10. I don't use balanced cables so I don't mind about them much. Anyone have tried all three and could give me a little rundown? That would be extremely helpful, thank you so much.



first try something with a higher impedance and lower sensitivity than the iem you are using.  A lot of iems will pick up some hiss on high potency amps as they just don't need that much power and the noise floor becomes evident when fed more than they like.   If the noise is still there when using a 300Ohm over-ear then you have a microphonics issue and start juggling pieces (tubes, cables, etc) to find and remove it.


----------



## FyxeHexyz (Jun 18, 2021)

Wiljen said:


> first try something with a higher impedance and lower sensitivity than the iem you are using.  A lot of iems will pick up some hiss on high potency amps as they just don't need that much power and the noise floor becomes evident when fed more than they like.   If the noise is still there when using a 300Ohm over-ear then you have a microphonics issue and start juggling pieces (tubes, cables, etc) to find and remove it.


ah thank you for the clarification  I'll try to check for those then.

Edit/Update:- I re-seated the tubes and they're gone but I can still hear a very soft like... "shhhhh" sound thingy. Are those just tubes?


----------



## Cran

Slim1970 said:


> I believe it can be used in that manner. You just need a 4mm to whatever dual output you need or you can get a male 4-Pin XLR to whatever dual output you need. Both should work just fine.


Sorry I was replying wrongly.  I should talk about your MT-604.

I see there are three output on the front.  Seems all of them are headphone out, but not line out.  Simply connect the 4mm (you mean 4.4mm?) output to another power amp will "power" the signal twice.   Please correct me if my understanding is wrong.


----------



## Slim1970 (Jun 18, 2021)

> Sorry I was replying wrongly.  I should talk about your MT-604.
> 
> I see there are three output on the front.  Seems all of them are headphone out, but not line out.  Simply connect the 4mm (you mean 4.4mm?) output to another power amp will "power" the signal twice.   Please correct me if my understanding is wrong.



Yes there are three outputs on the front. One 4.4mm input, one 4-Pin XLR output and one 4.4mm output. Either output I'm assuming could be used to power another device making the MT-604 a preamp. You won't be powering a signal twice, you sending the same signal instead of to headphones to a different device where that unit becomes the power output source. MT-604 will then become the volume controller.


----------



## HTSkywalker

FyxeHexyz said:


> I have a question. Newbie here, I'm currently using my iem with the MT-602 + XD-05Plus (as DAC) and I hear a slight microphonic? (electrical-ish kinda sound). I was wondering if I should jump to the TA-10R or XA-10. I do know the XA-10 would be silent with most iem but does the TA-10R have less noise than the MT-602? I really like the sound and soundstage of the 602, it would be a shame to lose that if I switched to the XA-10. I don't use balanced cables so I don't mind about them much. Anyone have tried all three and could give me a little rundown? That would be extremely helpful, thank you so much.


IEMs are normally wonderful but I don't think they need any kind of headphone amp to shine, especially tube ones or even hybrids. Those amps usually needs a higher impedance cans.


----------



## FyxeHexyz (Jun 18, 2021)

HTSkywalker said:


> IEMs are normally wonderful but I don't think they need any kind of headphone amp to shine, especially tube ones or even hybrids. Those amps usually needs a higher impedance cans.


well true but they do open up the sound for me at least hmm~ I do like the MT-602, I'm looking for a solid state that can give me a similar sound. Warm and opennnn~ I was thinking of the Singxer SA-1.... probably would have to sell my kidney for it 

P.S. I do own a Sundara as well so the Singxer would still benefit me other than using it with IEM.

P.S.S. Have anyone tried the TA-10R with IEMs? My friend is offering to buy it for me so it's getting kinda hard to resist.... I can then ditch my MT-602 and let my XD-05+ rest from acting as a DAC while charging all the time lol


----------



## Cran

FyxeHexyz said:


> well true but they do open up the sound for me at least hmm~ I do like the MT-602, I'm looking for a solid state that can give me a similar sound. Warm and opennnn~ I was thinking of the Singxer SA-1.... probably would have to sell my kidney for it
> 
> P.S. I do own a Sundara as well so the Singxer would still benefit me other than using it with IEM.
> 
> P.S.S. Have anyone tried the TA-10R with IEMs? My friend is offering to buy it for me so it's getting kinda hard to resist.... I can then ditch my MT-602 and let my XD-05+ rest from acting as a DAC while charging all the time lol


I have singxer sa-1, warm and smooth.  Its at the mid range price range, you'll still have plenty left after trading your kidney


----------



## 40lb

Does anyone have driver issues with their Xduoo DAC/AMPS? Using the XA-10 for a while now, and when using Amazon Music, it won't go higher than 16 BIt/44.1kHz on their Ultra HD tracks, and Foobar does the same when playing 24Bit/96kHz FLAC.


----------



## CADCAM

I have had my 602 for a few days now and am super impressed. Installed now is a pair of 67' Sylvania 5654's and I'm totally impressed by the sound. Feeding it from a SMSL SU-8 DAC which has a volume control, very useful with this amp.
Just ordered a pair of 1953 Sylvania 6AK5 and have heard good things about them... I'm doubtful, but hoping sound gets even better. Either way this ones a keeper, hope the tube sockets hold up to rolling. So far only tried it with my Superlux trio ~ HD672, HD668b & EVO drives them all effortlessly.


----------



## CADCAM (Jul 2, 2021)

SoundGuru said:


> I just picked up one of these. Its very powerful. I cant listen to Grados (32 ohm) with it as it gets way too loud. Its good with the HD650 though. Build quality is really nice and it is very quiet. I changed the stock tubes to some GE ones, not sure if its a big difference might change it back to the Chinese ones. Definitely recommended!


Try some Sylvania's from the 60's...amazing!


----------



## LongBeforeShort

Wiljen said:


> If you want a drive anything tube amp in the Ta series look at the Ta-30.  It has a lot of tube character and reacts to changes in rectifier as well (faster recovery time, less sag etc).    Being a hybrid with an output transformer makes it suitable for planars and other low impedance headphones that don't like OTL designs.


There is a catch though, the gain is so high, that its painful to adjust even driving more demanding headphones, for example the Hifiman Arya. Other than that it's a great.


----------



## Wiljen

LongBeforeShort said:


> There is a catch though, the gain is so high, that its painful to adjust even driving more demanding headphones, for example the Hifiman Arya. Other than that it's a great.


True, it isn't the best choice for high sensitivty, low impedance models unless you have some volume adjustment before it in the chain.  I've found using a -8dB pre-amp setting in foobar helps for times I need more usable volume range on the Ta-30.


----------



## amiltonc

Wiljen said:


> True, it isn't the best choice for high sensitivty, low impedance models unless you have some volume adjustment before it in the chain.  I've found using a -8dB pre-amp setting in foobar helps for times I need more usable volume range on the Ta-30.


I read your excellent article and saw that you have a lot of experience with tubes. Based on your article, I'm looking for a pair of Sylvania 50s to 70s to my Xduoo MT 602; a local seller told me that the Sylvania 1967 6ah6wa is compatible, but I couldn't find any information online.

Based on your experience, do you believe the 6ah6wa (cv 5450) tube would actually work on the Xduoo MT 602?


----------



## Wiljen

amiltonc said:


> I read your excellent article and saw that you have a lot of experience with tubes. Based on your article, I'm looking for a pair of Sylvania 50s to 70s to my Xduoo MT 602; a local seller told me that the Sylvania 1967 6ah6wa is compatible, but I couldn't find any information online.
> 
> Based on your experience, do you believe the 6ah6wa (cv 5450) tube would actually work on the Xduoo MT 602?



I wouldn't make that swap.  The 6ah6wa is closest to the 6J5 Chinese tube, not the 6J1 used in the 602.


----------



## LongBeforeShort (Jul 1, 2021)

Wiljen said:


> True, it isn't the best choice for high sensitivty, low impedance models unless you have some volume adjustment before it in the chain.  I've found using a -8dB pre-amp setting in foobar helps for times I need more usable volume range on the Ta-30.


Yes, if you have the chance to use pre amplifyer Setting its a great device, otherwise it will be hard to find the right volume, or even dangerous if you turn up by mistake. Asking myself, if they were testing with susvara alone...  Theyput also a lot of effort into that bluetooth unit, very powerful with super long range and stability.

xduoo seems to have a lot of interesting offerings in a fair price range, to be honest, as well as different design. Can't watch rectangle boxes anymore.


----------



## CADCAM

The 1953 Sylvania 6AK5 tubes came in today, they were suppose to be NOS but the pins were pretty dirty\oxidized so perhaps they have seen some use. I use a 220 fine sandpaper very lightly first then clean them with 91% alcohol repeat with fine emery paper then another alcohol rinse.  Sound is very good but I am wondering if the 67' Sylvania 6564 didn't sound even better in the 602...
I did notice the 6AK5's have silver\grey plates and the 6564 have black plates. I've read the black plates dissipate heat better but in this application I don't think that's even an issue. Anyone know any good info on plate material and color differences?
The treble is different. Don't know if that could mean they've been used or if they are NOS and needs a bit of burn-in time.
Listening now though and it does sound awful good! I'll let them burn-in a few more hours and take a close listen.


----------



## Wiljen

CADCAM said:


> The 1953 Sylvania 6AK5 tubes came in today, they were suppose to be NOS but the pins were pretty dirty\oxidized so perhaps they have seen some use. I use a 220 fine sandpaper very lightly first then clean them with 91% alcohol repeat with fine emery paper then another alcohol rinse.  Sound is very good but I am wondering if the 67' Sylvania 6564 didn't sound even better in the 602...
> I did notice the 6AK5's have silver\grey plates and the 6564 have black plates. I've read the black plates dissipate heat better but in this application I don't think that's even an issue. Anyone know any good info on plate material and color differences?
> The treble is different. Don't know if that could mean they've been used or if they are NOS and needs a bit of burn-in time.
> Listening now though and it does sound awful good! I'll let them burn-in a few more hours and take a close listen.



That is not at all uncommon for a tube that has sat 50 years.  They are probably NOS and just have 50 years worth of corrosion on the pins.  If cleaned up, I suspect they will work just fine.


----------



## CADCAM

Wiljen said:


> That is not at all uncommon for a tube that has sat 50 years.  They are probably NOS and just have 50 years worth of corrosion on the pins.  If cleaned up, I suspect they will work just fine.


They ended up sounding fantastic as the hours went on but I'm not sure if it was the tube getting better and better or my ear\brain adjusting to the sound. I am an old skool converted audiophile, trust my ears to some extent and believe the 67' 5654's might have sounded even better than the 53' 6AK5's. Either way it was an enjoyable listening session. Do you happen to know if the earlier tubes had the grey plates and the "newer" had black? I'd be interested in hearing a black plate from the 50's if they exist...


----------



## Wiljen

CADCAM said:


> They ended up sounding fantastic as the hours went on but I'm not sure if it was the tube getting better and better or my ear\brain adjusting to the sound. I am an old skool converted audiophile, trust my ears to some extent and believe the 67' 5654's might have sounded even better than the 53' 6AK5's. Either way it was an enjoyable listening session. Do you happen to know if the earlier tubes had the grey plates and the "newer" had black? I'd be interested in hearing a black plate from the 50's if they exist...



I'll have to take a look at some of my reference books and see if I can find the exact years of the black-plates.  The dates change per maker and per tube but generally were a late 50 and 1960s item.  I do know that gray plates exist on either side of that range so early 50s are gray and 70s are gray just not sure of exact start stop dates on the black plate.


----------



## CADCAM

Wiljen are you the one who wrote the article on tube rolling for the MT-602 on audiofoolreview?


----------



## Wiljen

CADCAM said:


> Wiljen are you the one who wrote the article on tube rolling for the MT-602 on audiofoolreview?


yep, I am audiofool.reviews, it's my blog.  Working on a 604 article to go with it now.


----------



## CADCAM

So I switched back to the 67' Sylvania 5654's in the MT-602 amp and they do sound better than the 53' Sylvania 6AK5's, now I'm not saying another pair of old 6AK5's wouldn't thrash the 67's but this particular set of 5654's sound freaking amazing! Listening now and right away bass is present, tight, right there...also treble is detailed and accurate, guitars sound so "textury" and piano even sounds realistic. That bass though! With the 6AK5's I was constantly swapping cd's and changing tracks but with the 5654's I'm not touching anything just listening. That is a good indicator. 
Listening to physical cd's btw with a NAD cd player, SMSL SU-8 DAC and Superlux HD668b & EVO cans. Also listened with my HE400i with great results.
More to come as I have DT990's and several other cans to check out on this little wonder amp.


----------



## amiltonc

Wiljen said:


> I wouldn't make that swap.  The 6ah6wa is closest to the 6J5 Chinese tube, not the 6J1 used in the 602.


Thanks!
I had only found this option in my country, I refused that, luckily the seller found a pair of Sylvania 6ak5 D getter in stock, it cost twice the price of the 6ah6wa and he doesn't know the date of these D getter tubes, but how was it the only one that I found, I bought it anyway. Hoping for it to be as good as what you tested.


----------



## pomegren8

I'm totally new to tubes and am considering buying a nice entry to hybrid tube amps just to have a slightly warmer source. I have the Topping E30-L30 and am loving how clean things are. I dont really want something to overly smear details. Just enough warmth to make things pleasurable but not to the expense of loosing details. How does a 2 tube amp like the MT-602 differ from the Vali 2/ 2+ ?
Also I'm guessing tube rolling is a lot simpler with the Vali since it's just one tube. But I also wonder if the 602 is considered an upgrade from the Vali or vise versa? Or at the same level. Do any of them power IEMs well or are they too noisy? Also are either also enough to power a Sundara or hd600?


----------



## CADCAM

pomegren8 said:


> I'm totally new to tubes and am considering buying a nice entry to hybrid tube amps just to have a slightly warmer source. I have the Topping E30-L30 and am loving how clean things are. I dont really want something to overly smear details. Just enough warmth to make things pleasurable but not to the expense of loosing details. How does a 2 tube amp like the MT-602 differ from the Vali 2/ 2+ ?
> Also I'm guessing tube rolling is a lot simpler with the Vali since it's just one tube. But I also wonder if the 602 is considered an upgrade from the Vali or vise versa? Or at the same level. Do any of them power IEMs well or are they too noisy? Also are either also enough to power a Sundara or hd600?


I have the Loxjie P20 & the Xduoo MT602 both hybrid tube amps. I won't say either is super "tubey" sounding the 602 with Sylvania 5654's sound a bit forward but does not smear anything and sounds excellent IMHO. I have read the little Xduoo's are not suitable for sensitive IEM's. Volume pot on the 602 is aggressive so a volume on your DAC would be welcome with most headphones. I'm listening right now and my DAC volume is set at 20 and goes up to 36.
Never owned any Shiit equipment so can't comment. I will say my Little Dot MKIII and Monoprice Monolith amps have more of that classic "tube sound" than either of my hybrids. 
As for power the 602 could probably power most headphones out there, seems like the gain is cranked up a bit on this one. I love the little $#!+ though so far and it has become my go to amp for listening lately. Very impressed with it.


----------



## pomegren8

CADCAM said:


> I have the Loxjie P20 & the Xduoo MT602 both hybrid tube amps. I won't say either is super "tubey" sounding the 602 with Sylvania 5654's sound a bit forward but does not smear anything and sounds excellent IMHO. I have read the little Xduoo's are not suitable for sensitive IEM's. Volume pot on the 602 is aggressive so a volume on your DAC would be welcome with most headphones. I'm listening right now and my DAC volume is set at 20 and goes up to 36.
> Never owned any Shiit equipment so can't comment. I will say my Little Dot MKIII and Monoprice Monolith amps have more of that classic "tube sound" than either of my hybrids.
> As for power the 602 could probably power most headphones out there, seems like the gain is cranked up a bit on this one. I love the little $#!+ though so far and it has become my go to amp for listening lately. Very impressed with it.


are there any tubes that you can roll on these for a more classic tubey sound just to get a taste of what's the warmest audio hug you can get? or is that really up to the bigger dog tubes. lol! 
602 definitely piqued my interest and is an my radar. especially with the sylvanas i read about that increase soundstage while maintaining clarity. unfortunately no sellers in my local market for sylvanas and will probably have to import tubes from ebay or something to the Philippines. 

does decreasing dac volume help with decreasing noise for IEMs? i also see those noise reduction 3.5 to 3.5 adaptors, do those work too or are they not worth the time? 
im particularly curious in tubing the HZSound Heart Mirror actually as i heard it might go well with tubes. will have to see if it's too lean for my taste on my topping stack first. should arrive anytime this week.


----------



## CADCAM

pomegren8 said:


> are there any tubes that you can roll on these for a more classic tubey sound just to get a taste of what's the warmest audio hug you can get? or is that really up to the bigger dog tubes. lol!
> 602 definitely piqued my interest and is an my radar. especially with the sylvanas i read about that increase soundstage while maintaining clarity. unfortunately no sellers in my local market for sylvanas and will probably have to import tubes from ebay or something to the Philippines.
> 
> does decreasing dac volume help with decreasing noise for IEMs? i also see those noise reduction 3.5 to 3.5 adaptors, do those work too or are they not worth the time?
> im particularly curious in tubing the HZSound Heart Mirror actually as i heard it might go well with tubes. will have to see if it's too lean for my taste on my topping stack first. should arrive anytime this week.


I never even tried the stock tubes but heard they are actually pretty good. https://audiofool.reviews/tube-rolling-the-xduoo-mt-602/ does a tube rolling article that was helpful. I have only tried 1967 Sylvania 5654 black plates which I love and 1953 Sylvania 6AK5 grey plates that were good but not as good as the 5654's IMHO. 
I think a volume control before the amp is almost a prerequisite with this unit unless you have something difficult to drive.


----------



## CJG888

pomegren8 said:


> are there any tubes that you can roll on these for a more classic tubey sound just to get a taste of what's the warmest audio hug you can get? or is that really up to the bigger dog tubes. lol!
> 602 definitely piqued my interest and is an my radar. especially with the sylvanas i read about that increase soundstage while maintaining clarity. unfortunately no sellers in my local market for sylvanas and will probably have to import tubes from ebay or something to the Philippines.
> 
> does decreasing dac volume help with decreasing noise for IEMs? i also see those noise reduction 3.5 to 3.5 adaptors, do those work too or are they not worth the time?
> im particularly curious in tubing the HZSound Heart Mirror actually as i heard it might go well with tubes. will have to see if it's too lean for my taste on my topping stack first. should arrive anytime this week.



Mullard CV4010s might do it.


----------



## Zbell

Anyone have experience or thoughts pairing an HE6se with the xDuoo TA-30?


----------



## HTSkywalker

If you are looking for a real Tubey sound, get the Darkvoice or for a Hybrid get the Cavalli CTH which will also excel with Planars


----------



## tkddans

Zbell said:


> Anyone have experience or thoughts pairing an HE6se with the xDuoo TA-30?


I use the HE6SE V2 on the TA-30, and it works wonderfully with plenty headroom. All tube, and lots of power. Pretty compact on the desk too.

Zero complaints and only good things to say, especially with the tubes I use.


----------



## amiltonc

CADCAM said:


> I never even tried the stock tubes but heard they are actually pretty good. https://audiofool.reviews/tube-rolling-the-xduoo-mt-602/ does a tube rolling article that was helpful. I have only tried 1967 Sylvania 5654 black plates which I love and 1953 Sylvania 6AK5 grey plates that were good but not as good as the 5654's IMHO.
> I think a volume control before the amp is almost a prerequisite with this unit unless you have something difficult to drive.


The annoying thing about this article is knowing that the best tube for the MT 602 would be the Sylvania 6ak5 from 1950 to 1968, as I understand it. It's very difficult to find tubes on these specific dates, I bought the only Sylvania 6ak5 pair available in my country, but the seller didn't know the date and I didn't find it either, because the code on the tube is C1E - 139 (C1E is below 6ak5 and 139 stands vertically on the tube), but I did a lot of research and didn't find any information on how to know the date through these codes.


----------



## jsmiller58 (Jul 6, 2021)

Sorry if this has already been covered…. For those looking to pick up the MT602, I would mention they are incredibly powerful with no gain setting I can discern…. And that power brings up what I see as trouble…. The volume pot ha tremendous channel imbalance at low volumes…. So if you are listening to hard to drive cans you likely will find the volume uncomfortably loud before you turn the volume up to levels where this s no longer an issue…. If your DAC / source has volume controls you should be good!


----------



## CJG888

I also find this to be a major issue. There must be some way of reducing the gain. Attenuating the input will result in a loss of quality.

I suspect Xduoo just wanted to optimise their paper specifications, and threw the baby out with the bathwater.

Worst case, I will try a different volume pot. The correct solution, however, would be to reduce the gain in the solid state section.

Frankly, it looks like there is a great budget amp in there, trying to get out - but it will take some modding. Or just use it exclusively with planars!


----------



## tudedude

amiltonc said:


> The annoying thing about this article is knowing that the best tube for the MT 602 would be the Sylvania 6ak5 from 1950 to 1968, as I understand it. It's very difficult to find tubes on these specific dates, I bought the only Sylvania 6ak5 pair available in my country, but the seller didn't know the date and I didn't find it either, because the code on the tube is C1E - 139 (C1E is below 6ak5 and 139 stands vertically on the tube), but I did a lot of research and didn't find any information on how to know the date through these codes.


I have some 1950s sylvania tubes and honestly I'm not hearing any expansive soundstage as the article describes.  I have a feeling the writer of the article is really exaggerating or has some incredible golden ears. The characteristic that stands out to me with the sylvanias are crisper more glassy highs compared to the stock tubes but that could be just placebo mind tricks. The tubey influence on this hybrid amp is very subtle if in my opinion.


----------



## CJG888

Maybe too much of the gain is being produced by the solid state amplification stage…


----------



## CADCAM

amiltonc said:


> The annoying thing about this article is knowing that the best tube for the MT 602 would be the Sylvania 6ak5 from 1950 to 1968, as I understand it. It's very difficult to find tubes on these specific dates, I bought the only Sylvania 6ak5 pair available in my country, but the seller didn't know the date and I didn't find it either, because the code on the tube is C1E - 139 (C1E is below 6ak5 and 139 stands vertically on the tube), but I did a lot of research and didn't find any information on how to know the date through these codes.


As I said earlier I already had the 1967 Sylvania 5654 from my Little Dot MKIII amp and installed them in the 602 as soon as it arrived and they are fantastic. 
After reading the article on rolling I went on fleabay and searched until I found a pair of 1953 Sylvania 6AK5's purchased them installed and listened pretty extensively but felt they were not superior to the 67' 5654's.
It may be the pair I have though and I wish I could try another pair of 6AK5's from the early 50's in my 602, it would be amazing if it could sound even better!


----------



## CADCAM

tudedude said:


> I have some 1950s sylvania tubes and honestly I'm not hearing any expansive soundstage as the article describes.  I have a feeling the writer of the article is really exaggerating or has some incredible golden ears. The characteristic that stands out to me with the sylvanias are crisper more glassy highs compared to the stock tubes but that could be just placebo mind tricks. The tubey influence on this hybrid amp is very subtle if in my opinion.


My 67' Sylvania's are a bit forward sounding in the mids which works out great for guitar and piano and the bass is incredible! I think instrument separation is also very very good for an amp at this price point. 
The 53' 6AK5 were also very good and if anyone in the US wants to try them I'll sell for exactly what I paid for them $22.00 bucks


----------



## amiltonc

tudedude said:


> I have some 1950s sylvania tubes and honestly I'm not hearing any expansive soundstage as the article describes.  I have a feeling the writer of the article is really exaggerating or has some incredible golden ears. The characteristic that stands out to me with the sylvanias are crisper more glassy highs compared to the stock tubes but that could be just placebo mind tricks. The tubey influence on this hybrid amp is very subtle if in my opinion.


I understand what you mean, I already had the Bravo Ocean and the Hifiman EF5, both used 12AU7 tubes, I tried several and the difference was always very subtle, to the point that I didn't think it was worth the expense with the tubes, and in the end, I preferred the new Russian Genalex Gold Lion to the NOS. Well, I've already received the 6ak5 Sylvania D Getter, I don't know the date, I still have to receive the MT602 now, it's already in my country for delivery, so I'm going to compare the Chinese tube with these Sylvania.


----------



## amiltonc

CADCAM said:


> My 67' Sylvania's are a bit forward sounding in the mids which works out great for guitar and piano and the bass is incredible! I think instrument separation is also very very good for an amp at this price point.
> The 53' 6AK5 were also very good and if anyone in the US wants to try them I'll sell for exactly what I paid for them $22.00 bucks


How is your Sylvania 1953 code written? Mine is D getter, and I read that D getter used to be used in the 50s, so I wanted to confirm if my 6ak5 Sylvania is really from this decade. My Peer has written under the description 6ak5, B1E on one tube and C1E on the other, and both vertically have written code 139.


----------



## amiltonc

It appears that the 3-digit code indicates the week and year, where the first digit would be the year ending with that number, and the other 2 digits would be the week; my pair is code 139, so it's a tube made in the thirty-ninth week of a year ending in 1. Since it's a black plate with Getter D, with a green and black box, I've come to the conclusion that my tubes are from 1951, so it must have the magic described in the Audiofool Reviews article.


----------



## CADCAM (Jul 7, 2021)

Mine came in the original boxes. 12/53 & 8/53
I'll try and post some pics of the tubes if I get a chance.


----------



## Wiljen

pomegren8 said:


> I'm totally new to tubes and am considering buying a nice entry to hybrid tube amps just to have a slightly warmer source. I have the Topping E30-L30 and am loving how clean things are. I dont really want something to overly smear details. Just enough warmth to make things pleasurable but not to the expense of loosing details. How does a 2 tube amp like the MT-602 differ from the Vali 2/ 2+ ?
> Also I'm guessing tube rolling is a lot simpler with the Vali since it's just one tube. But I also wonder if the 602 is considered an upgrade from the Vali or vise versa? Or at the same level. Do any of them power IEMs well or are they too noisy? Also are either also enough to power a Sundara or hd600?



Tube rolling isn't necessarily any easier with a single tube as the internal sections often need to be balanced to prevent volume imbalances when using a single tube to handle both channels.  A pair of tubes may well be more forgiving as the two triodes are averaged in the final output so small imbalances may be hidden in the output.   If I was gunning for something that adds some warmth without going into huge expense, I'd probably look at something like the Ta-10r with either a good Mullard or Amperex tube.


----------



## pomegren8

Wiljen said:


> Tube rolling isn't necessarily any easier with a single tube as the internal sections often need to be balanced to prevent volume imbalances when using a single tube to handle both channels.  A pair of tubes may well be more forgiving as the two triodes are averaged in the final output so small imbalances may be hidden in the output.   If I was gunning for something that adds some warmth without going into huge expense, I'd probably look at something like the Ta-10r with either a good Mullard or Amperex tube.


but the TA-10R is more expensive than the 602 haha! so i guess the warmer sources really are priced higher up and the cheaper hybrids really are more transparent in general?

I'd have to audition a full fledged warm source somewhere before shelling out money for that. Not sure if I like super warm sources. I just want a taste for now. I'm pretty sure my preferences are for the transparent types anyways altho I'm quite intrigued in how the 602 can warm up the mids without the expense of losing too much detail depending on what tube you put.

Here's an example. If you're familiar with the Moondrop Aria vs Starfield. I didn't like the starfield because it was too warm and smeared the details for my taste esp in the treble area. But I did appreciate the warmth of its midrange.

And I'm mainly curious in how the 602 can warm up the Sundara's mids. I heard it's no problem with planars since it's a hybrid anyways


----------



## Wiljen

pomegren8 said:


> but the TA-10R is more expensive than the 602 haha! so i guess the warmer sources really are priced higher up and the cheaper hybrids really are more transparent in general?
> 
> I'd have to audition a full fledged warm source somewhere before shelling out money for that. Not sure if I like super warm sources. I just want a taste for now. I'm pretty sure my preferences are for the transparent types anyways altho I'm quite intrigued in how the 602 can warm up the mids without the expense of losing too much detail depending on what tube you put.
> 
> ...



i'd probably give the Western Digital 403b a try in the 602 then as it is likely to be the tube of choice for warmth.  I picked it #2 in the 602 and #1 in the 604 so it consistently performs near the top.   I do think the 6AK5 in general does not get as warm as the 12au7 can which is why I suggested the 10r if you want a really warm source.


----------



## CADCAM

After having this amp (MT-602) for a while now I believe a DAC with a volume control is a prerequisite. I'm not sure how I would have listened to some of my headphones without being able to turn the volume down downstream. I have the SMSL SU-8 DAC and with it this amp is a keeper IMHO.


----------



## CJG888

You can buy inline attenuators or attenuated phono cables…


----------



## pomegren8

I do have the Topping E30 and it has a preamp mode where I can set the volume so I think I'm pretty much set if ever I pull the trigger on the 602. So far that's what I'm most interested in.
I probably should write down the tube options and go window shopping sometime on what's available locally and if I have to go to ebay and source some there. Thanks for the insights! It might be a while tho as I kinda want a nice dynamic driver headphone first before dipping my toes into hybrids. either the 6xx or the 660s


----------



## CJG888

Why not the classic HD600?


----------



## CADCAM

I had the HD600 and they sounded good but hurt my jaw. I'm a pretty big guy and have a big head btw and it may have been the oval shape of the cups but had to sell them. My jaw would ache after a listening session. YMMV


----------



## Jonmakauu

Is the TA-26 an OTL Tube amp? Wouldn't make sense to just make it single ended if it were just another hybrid like a lot of their tube amps.


----------



## Barndoor

Can't beat a bit of tube glow on a winter's day


----------



## jsmiller58

Barndoor said:


> Can't beat a bit of tube glow on a winter's day


Winter…. It has been incredibly hot and dry here in the western part of the US…. Could use some of that winter!

I haven’t had much of a chance to use my 602 for a while, so I envy you that as well!


----------



## Barndoor

jsmiller58 said:


> Winter…. It has been incredibly hot and dry here in the western part of the US…. Could use some of that winter!
> 
> I haven’t had much of a chance to use my 602 for a while, so I envy you that as well!


I'll take that sunshine. We are getting hit by storm after storm at the moment


----------



## pomegren8

I'm wondering for all the 602 users here, how hot does the 602 get? and what ambient temperatures are you having in your respective places?
Also is there a maximum temperature recommended for the tubes before it's too hot for usage?


----------



## CADCAM (Jul 9, 2021)

pomegren8 said:


> I'm wondering for all the 602 users here, how hot does the 602 get? and what ambient temperatures are you having in your respective places?
> Also is there a maximum temperature recommended for the tubes before it's too hot for usage?


I have measured 105°F degrees max at the tubes themselves, I do have central air and the room is set to 74°F. No heat issues here my Monolith in the same room has hit over 300°F at the tubes.


----------



## CJG888

I can second that. Heat is negligible. 

The Tzar’s 6S41S get up to 260C, though. You could sear steak on that, never mind fry an egg!


----------



## mikemuzak

pomegren8 said:


> I'm wondering for all the 602 users here, how hot does the 602 get? and what ambient temperatures are you having in your respective places?
> Also is there a maximum temperature recommended for the tubes before it's too hot for usage?


No they really don't. I took the side panel off the other day to get a better look and sure enough there are two little LEDs directly below the tubes. I pulled the tubes out and flipped the power switch to the ON position and sure enough they lit up. So I don't know if the the 6J1 tubes and/or equivalent even produce a glow at all.


----------



## jsmiller58

mikemuzak said:


> No they really don't. I took the side panel off the other day to get a better look and sure enough there are two little LEDs directly below the tubes. I pulled the tubes out and flipped the power switch to the ON position and sure enough they lit up. So I don't know if the the 6J1 tubes and/or equivalent even produce a glow at all.


Thanks for confirming what most have surmised - LEDs produce the glow.  It is a nice touch by Xduoo, and a little deceptive, at the same time!


----------



## CADCAM

mikemuzak said:


> No they really don't. I took the side panel off the other day to get a better look and sure enough there are two little LEDs directly below the tubes. I pulled the tubes out and flipped the power switch to the ON position and sure enough they lit up. So I don't know if the the 6J1 tubes and/or equivalent even produce a glow at all.


They are going to glow and light up as any other tube would, Xduoo mounted lighting under tubes to "enhance" the tube effect. The tubes are definitely working and used in the circuitry as swapping tubes changes sound characteristics. I had heard of all the tubes not being used in the 604 but Z's review proves that wrong.


----------



## Wiljen

my 604 review went up today here and my blog.  https://www.head-fi.org/showcase/xduoo-mt-604-balanced-tube.25147/reviews#review-26233 

Tube rolling article is also done and up (blog only for now).


----------



## amiltonc

One more here to report that the Xduoo MT 602 doesn't heat up; mine arrived today and so far impressed me in 2 things, the first is the fact that it doesn't heat up absurdly and the second is the silence, I don't hear any noise even with it at full volume without playing music. I've had 2 hybrids, the Bravo Ocean and the Hifiman EF5, and both were very hot, the Bravo Ocean even more, it even bothered the hand when playing, and the Bravo Ocean had noise even at low volumes , without playing music, we always heard the hiss, when playing the music, they were not audible as the music was louder, on the other hand, the EF5 had noise at a volume close to the maximum.
For now I have the same Chinese 6J1, later I'll put on my 1951 Sylvania and see if the heat and noise issue changes.


----------



## CADCAM (Jul 10, 2021)

Installed my Yugoslavian 6HM5's today in the MT-602...very nice! They run around 95 degrees (if anyone is interested) and sound fantastic, I still believe the 67' Sylvania 5654's are the best sounding tube thus far though. The Yugo's have great mid range detail and bass is pretty good from my HE400i but the Sylvania tubes had better low end IMO. I love the fact the 6HM5 are tall bottles as swapping tubes is a pain with this little amp. 
Switching to my Superlux EVO bass is registering a bit lower and I might even like this combo better! Listening to Alasdair Fraser, Stanley Clarke and Dizzy Gillespie...very musical and at this price point not much to criticize.
100 dollar amp with 40 dollar headphones just shouldn't sound this good! Great hobby!


----------



## tkddans

If anyone is in the market for a tube amp, or looking to move to a more tube heavy tube set from a smaller hybrid setup, Drop has the TA-30 out again now.

I own it myself and have no complaints, plus the fun and visual aesthetic of seeing the small tubes as well as the larger rectifier on the desk


----------



## CADCAM (Jul 13, 2021)

Great listening session with the 602 with the Yugoslavian tubes! Listened to Niacin ~ High Bias which is a HDCD straight through. Started with the Superlux EVO's but they struggled just a bit with the complexity of the music so I switched to my HE400i and they did the job. If you want to see if your system can hang try some Niacin, Sheehan is a beast on bass and Dennis Chambers is possibly my favorite drummer. Talk about PRaT!




Rockin' the tall bottles in the 602


----------



## Galapac (Jul 12, 2021)

CADCAM said:


> Great listening session with the 602 with the Yugoslavian tubes! Listened to Niacin ~ High Bias which is a HDCD straight through. Started with the Superlux EVO's but they struggled just a bit with the complexity of the music so I switched to my HE400i and they did the job. If you want to see if your system can hang try some Niacin, Sheehan is a beast on bass and Dennis Chambers is possibly my favorite drummer. Talk about PRaT!


If you like Niacin, you’ll like Octavarium by Dream Theater
it has elements of Pink Floyd, Deep Purple, and Rush rolled into one.


----------



## CADCAM

Galapac said:


> If you like Niacin, you’ll like Octavarium by Dream Theater
> it has elements of Pink Floyd, Deep Purple, and Rush rolled into one.



Big early DT fan here!


----------



## Wiljen

I've got the new Ta-26 on its way here so a new tube rolling journey begins.  6AS7/6SN7GT combo in this one.


----------



## CJG888

Looks like Xduoo‘s answer to the 336i…


----------



## Galapac

Wiljen said:


> I've got the new Ta-26 on its way here so a new tube rolling journey begins.  6AS7/6SN7GT combo in this one.



Interesting. I did a search of 6N5P and it shows an entirely different tube than what is pictured. I wonder if they mean the 6N5PJ, which is similar to 6AS7G tube.
Anyway this appears to be a possible competitor to the Dark Voice with better components.

I would be interested in your evaluation when you receive it!


----------



## Wiljen

Galapac said:


> Interesting. I did a search of 6N5P and it shows an entirely different tube than what is pictured. I wonder if they mean the 6N5PJ, which is similar to 6AS7G tube.
> Anyway this appears to be a possible competitor to the Dark Voice with better components.
> 
> I would be interested in your evaluation when you receive it!


Yep, the 6N5P moniker is confusing as it seems that Chinese and Russian references correlate to two very different tubes with the Russian references being a 9-pin noval miniature quite similar to the 1539 and the Chinese being an octal and a much larger tube and a clone of the 6AS7G.     I can confirm the correct tubes are indeed 6SN7GT and 6AS7G based on conversations with reps.


----------



## Zbell

Sup all - Just FYI / PSA - The Xduoo TA-30 Dac/Amp is available on Drop for $599 with about $90 in store credit added on top. However, if you purchase through Drop you will not have a warranty.

Also wanted to post this and mention that Apos Audio has a price match program of sorts. Reach out to their support and provide a link to active Drop page and they should match the $599 price and it will include a 2-year warranty and an awesome Apos customer service experience (and you don't have to wait 2 months for shipping). With that said, you'll likely miss out on the $90 in store credit you could get through Drop.


----------



## CADCAM

Wiljen 
what do you think of the 6HQ5 Sylvania? It's a tall bottle so easier for rolling and I love the sound of the current Sylvania's I have...


----------



## Wiljen

CADCAM said:


> Wiljen
> what do you think of the 6HQ5 Sylvania? It's a tall bottle so easier for rolling and I love the sound of the current Sylvania's I have...


The 6HQ5 has 200mA heater current vs the 6ak5 175mA,  a plate current of 11.5mA vs 7.5mA for the 6AK5, and the maximum plate voltage is also higher at 200V vs 180V for the 6AK5.  While it may work, it could shorten the life of other components as it needs more power to supply the tube than the original design called for.    If Xduoo used fairly wide tolerances it maybe perfectly safe, but without confirming with their engineers, I'd be hesitant to try it.


----------



## CADCAM

Wiljen said:


> The 6HQ5 has 200mA heater current vs the 6ak5 175mA,  a plate current of 11.5mA vs 7.5mA for the 6AK5, and the maximum plate voltage is also higher at 200V vs 180V for the 6AK5.  While it may work, it could shorten the life of other components as it needs more power to supply the tube than the original design called for.    If Xduoo used fairly wide tolerances it maybe perfectly safe, but without confirming with their engineers, I'd be hesitant to try it.


Do you know if they (Xduoo) has a representative here on Head-FI that I could ask?


----------



## Ichos

I don't know if you people are aware of it but Apos is doing a giveaway of the xduoo MT - 602.

You can enter here.

https://apos.audio/blogs/news/apos-audio-xduoo-mt-602-tube-class-a-headphone-amplifier-giveaway


----------



## FyxeHexyz

Greetings people~
Here I am again, still can't make a decision on what I want haha so I need more opinion.

I'm currently using an IEM (Acoustune HS1695ti. DD driver) and Hifiman Sundara on the MT-602. 
But I was thinking of getting the TA-10r or the XA-10. The reason I was thinking of switching is because it is really hard for me to get my hands on a 6j1 in my country and the shipping is pretty hellish. I can get the tubes the TA-10r uses since there is a shop here that sells em or I can just go with the XA-10. 

Regarding low hum noise with iem, the MT-602 has it but it's barely noticeable and disappears when I play music, so I think my iem is not particularly too sensitive. I really love the sound signature of the 602 (stock tubes). So I'm looking for something similar in sound? 

So which one would probably be a better choice?


----------



## Wiljen

CADCAM said:


> Do you know if they (Xduoo) has a representative here on Head-FI that I could ask?



Not that I am aware of. I've asked since I have some contacts there and we will see what is said.


----------



## CADCAM

So without question the 67' Sylvania 5654 is the "best" sounding tube I have tried in the 602. Tall bottle 6HM5 was very entertaining, the 53' Sylvania 6AK5 had some good attributes but the 5654 is just so musical. I have yet to try the Tung-Sol 6AK5W or 6J1-ev mostly because it's so difficult to get the short stubby tubes out, I feel like I may damage the socket and\or circuit board with the amount of rocking and effort you need to put in extracting those little tubes!
Do they make a tall Tung-Sol 6AK5W??


----------



## HTSkywalker

CADCAM said:


> So without question the 67' Sylvania 5654 is the "best" sounding tube I have tried in the 602. Tall bottle 6HM5 was very entertaining, the 53' Sylvania 6AK5 had some good attributes but the 5654 is just so musical. I have yet to try the Tung-Sol 6AK5W or 6J1-ev mostly because it's so difficult to get the short stubby tubes out, I feel like I may damage the socket and\or circuit board with the amount of rocking and effort you need to put in extracting those little tubes!
> Do they make a tall Tung-Sol 6AK5W??


Any luck with the Tung Sol ?


----------



## CADCAM

HTSkywalker said:


> Any luck with the Tung Sol ?


No, I haven't tried the Tung-Sol in the Xduoo yet but I hope to try it soon. I will say it is my favorite preamp tube for my Little Dot MKIII... even sounding better than the Yugoslavian 6HM5 or anything else I've tried.
The Tung-Sol's are even shorter than the Sylvania 5654 and I'm worried about getting them out if they don't sound better.


----------



## CADCAM

Wiljen said:


> Not that I am aware of. I've asked since I have some contacts there and we will see what is said.


I did hear back from Xduoo and they gave a short no on the 6HQ5 tube being an option in the MT-602.


----------



## dsrk

CADCAM said:


> So without question the 67' Sylvania 5654 is the "best" sounding tube I have tried in the 602. Tall bottle 6HM5 was very entertaining, the 53' Sylvania 6AK5 had some good attributes but the 5654 is just so musical. I have yet to try the Tung-Sol 6AK5W or 6J1-ev mostly because it's so difficult to get the short stubby tubes out, I feel like I may damage the socket and\or circuit board with the amount of rocking and effort you need to put in extracting those little tubes!
> Do they make a tall Tung-Sol 6AK5W??


I am interested in buying MT-602, can you help with the link for Sylvania 5654?
is this the same?
https://www.ebay.com/itm/184484228043


----------



## Wiljen

dsrk said:


> I am interested in buying MT-602, can you help with the link for Sylvania 5654?
> is this the same?
> https://www.ebay.com/itm/184484228043


yep those appear to be 1969 made Sylvania 5654s.  I can't vouch for the seller, but the tube does appear to the be the one we are discussing.


----------



## Wiljen

CADCAM said:


> I did hear back from Xduoo and they gave a short no on the 6HQ5 tube being an option in the MT-602.


Yep, just got the same today.   I thought the curves were far enough apart it wasn't likely to be a good idea but glad we got clarification.

W


----------



## CADCAM

dsrk said:


> I am interested in buying MT-602, can you help with the link for Sylvania 5654?
> is this the same?
> https://www.ebay.com/itm/184484228043


I found these and they seem to be exactly what I am using and was going to order another pair as backup\replacements but the seller could not sell me a matched pair. With the amount of tubes he sells you would think he has a tester but it seems he doesn't. I asked if he would sell a pair of 67's and he never got back to me...
I want to order a pair but it would be nice to get a pair electrically matched.
Wiljen what do you think??

https://www.ebay.com/itm/1849024280...rentrq:ed6bde1f17a0a1205e34647affec8840|iid:1


----------



## CADCAM

Wiljen said:


> Yep, just got the same today.   I thought the curves were far enough apart it wasn't likely to be a good idea but glad we got clarification.
> 
> W


It's funny I did try my Yugo 6HM5 and it sounded really good. Only listened for an hour or less and hope I didn't do any damage...
I know the 6HM5 and 6HQ5 are basically the same.


----------



## Wiljen

CADCAM said:


> It's funny I did try my Yugo 6HM5 and it sounded really good. Only listened for an hour or less and hope I didn't do any damage...
> I know the 6HM5 and 6HQ5 are basically the same.


I suspect you can get away with it short term as overloading a power supply tends to be one of those things that gradually takes a toll over time unless you really go way beyond what it can handle.    Small overages it will struggle with for quite awhile before failing usually,  big ones, not so much.


----------



## CADCAM

dsrk said:


> I am interested in buying MT-602, can you help with the link for Sylvania 5654?
> is this the same?
> https://www.ebay.com/itm/184484228043


I ended up buying a pair of these, the seller says they are heat tested...not sure what that actually means, probably not much but the tube(s) (and box) looks to be in excellent condition and I figured why not give them a try. When they come in I'll post thoughts.


----------



## omegaorgun

Have a like new TA-10 with 16 tubes if anyone wants to buy or trade.


----------



## SrTexugo

=)


----------



## jsmiller58

SrTexugo said:


> =)


That is a great looking set up - and I imagine it sounds glorious!


----------



## dsrk (Jul 30, 2021)

SrTexugo said:


> =)


WOW. looks vibrant!!!
Definitely taken on a DSLR.


----------



## HTSkywalker

SrTexugo said:


> =)


Deja vu in the Ananda thread 😂😂


----------



## HTSkywalker

Am happy you are parading your Ananda, I love it too 😍😍😍


----------



## Wiljen

I am working on the TA-26 review and comparing with a borrowed darkvoice 336se and my bottlehead crack w/speedball.    Build quality is better on the Ta-26 than the other two for sure as the metal is heavier and better finished vs Darkvoice and I built the Crack so it isn't up to the level of a few I have seen.  I'm sure some people have built gorgeous cases for their cracks but mine is pretty plain pine.      Tube rolling on the 26 is yielding some interesting results as well.   Lots of good choices for tubes with some old standbys being at or very near top of the charts (Mouse ears) and others at or near the bottom (Bad boys).    I'll have something posted likely the end of next week or the week after as I've got probably 35 different tubes in the mix on the 3 amps.


----------



## CoCostanza

How is 604 compared to 602? Is it a lot better? Is it worth to get a balanced dac and headphones just for it?


----------



## Wiljen

CoCostanza said:


> How is 604 compared to 602? Is it a lot better? Is it worth to get a balanced dac and headphones just for it?



I would not advocate getting a balanced dac and headphone just to use the 604.  It is a solid offering and would make a good addition to a collection that already has some of those pieces if you wanted an amp with a bit of warmth.     It is good kit, but maybe not build your whole system around it good.


----------



## HTSkywalker

Wiljen said:


> I am working on the TA-26 review and comparing with a borrowed darkvoice 336se and my bottlehead crack w/speedball.    Build quality is better on the Ta-26 than the other two for sure as the metal is heavier and better finished vs Darkvoice and I built the Crack so it isn't up to the level of a few I have seen.  I'm sure some people have built gorgeous cases for their cracks but mine is pretty plain pine.      Tube rolling on the 26 is yielding some interesting results as well.   Lots of good choices for tubes with some old standbys being at or very near top of the charts (Mouse ears) and others at or near the bottom (Bad boys).    I'll have something posted likely the end of next week or the week after as I've got probably 35 different tubes in the mix on the 3 amps.


And what's your impression comparing all 3 amps ? have a feeling the DV makes it on the top ? 🙂🙄🙄


----------



## dsrk (Jul 31, 2021)

Hi,

Received my MT-602 this morning. I can't locate my RCA cables, using AUX cable line out from my FiiO M11 Pro for now.

If I am really happy with its performance, I will think about investing in a decent DAC.

I am not much of a desktop user. If I feel the improvement is worth, I will start investing in desktop gear.

It's not that powerful compared to my XD-05 Plus. May be M11 line out is weak. But I am noticing slight improvement in sound quality. 

I have to order decent RCA cable now.

I never listened to a tube AMP, so I don't know how tuby it sounds.

But the initial impressions are positive.


----------



## Barnold Schwarzenficker

I recently purchased the MT-602 but noticed that the right tube (the smaller one) was not fully inserted into it's socket (the pins were showing) and that the tube was leaning to one side. I Removed the tube and indeed saw that one pin was bent. I contacted the seller and he provided me with a replacement. However that one too does not fully insert into the socket and from what I can see (photo's attached) one pin is preventing all the pins from being fully inserted and by now is probably bent as well.

I'm a complete novice when it comes to tube amplifiers but as far as I know the pins should not be showing.

The amp has no issues producing sound, I however find that sound not to be vastly different from most solid state amplifiers I have tried.

Please let me know what you think.


----------



## CADCAM

dsrk said:


> I am interested in buying MT-602, can you help with the link for Sylvania 5654?
> is this the same?
> https://www.ebay.com/itm/184484228043


I got those tubes in that you posted the link to and they sound excellent! I would say if you haven't go ahead and order a pair without hesitation. 
Mine looked new and even the boxes are in excellent shape being 52 years old!!!
The sound is at least on par with my 67's and percussion sounds especially good. 
Nice find!


----------



## dsrk

CADCAM said:


> I got those tubes in that you posted the link to and they sound excellent! I would say if you haven't go ahead and order a pair without hesitation.
> Mine looked new and even the boxes are in excellent shape being 52 years old!!!
> The sound is at least on par with my 67's and percussion sounds especially good.
> Nice find!


Thanks. But the seller does not ship to India unfortunately.


----------



## CADCAM

dsrk said:


> Thanks. But the seller does not ship to India unfortunately.


Oh man that sucks. Can I do anything? I'm in New England USA


----------



## dsrk (Aug 4, 2021)

CADCAM said:


> Oh man that sucks. Can I do anything? I'm in New England USA


I want to get them but don't know how.

Is there a noticeable improvement compared to the stock tubes?


----------



## CADCAM

dsrk said:


> I want to get them but don't know how.
> 
> Is there a noticeable improvement compared to the stock tubes?


I never tried the stock tubes but Wiljen might be able to chime in here and give an opinion...


----------



## CADCAM

While we're at it Wiljen do you think the 602 and HE400i would be a good pairing?


----------



## Jolterrrr

CADCAM said:


> It's funny I did try my Yugo 6HM5 and it sounded really good. Only listened for an hour or less and hope I didn't do any damage...
> I know the 6HM5 and 6HQ5 are basically the same.


Wait.. you cannot use Yugo 6HM5 in mt-602? 😥


----------



## CADCAM (Aug 5, 2021)

Jolterrrr said:


> Wait.. you cannot use Yugo 6HM5 in mt-602? 😥


I guess not...
I contacted Xduoo to ask about the 6HQ5 and they responded "no" that's it, no explanation, no elaboration, just no.
The 6HQ5 and 6HM5 are basically identical I've been told.


----------



## Jolterrrr

CADCAM said:


> I guess not...
> I contacted Xduoo to ask about the 6HQ5 and they responded "no" that's it, no explanation, no elaboration, just no.
> The 6HQ5 and 6HM5 are basically identical I've been told.


Hmm maybe that person dont know. So he says No instead? Must be a reason.


----------



## Jolterrrr

CADCAM said:


> I guess not...
> I contacted Xduoo to ask about the 6HQ5 and they responded "no" that's it, no explanation, no elaboration, just no.
> The 6HQ5 and 6HM5 are basically identical I've been told.


I asked Trolldragon at this forum and he Said.

"The 6J1 that the MT-602 uses is a pentode and the 6HM5 is a triode, if they are using the screen grid on that 6J1 then no you could not use a 6HM5 or any other triode in it's place."


----------



## dpump

Any experience using iems with the MT-601? Power output of 601 seems to be more inline with iem use versus regular headphones. As Wiljen said in his review, he thought the 6.35mm headphone jack on the 601 should have been 3.5mm to allow use of iems without an adaptor. I agree.


----------



## devin.oct (Aug 6, 2021)

Hello, anybody using MT-602?
Mine does a popping sound on my HD6XX when turning off the amp, it is about a listening volume, volume knob is at zero and source is muted, no popping sound when turning on though.
Anybody also experienced this? Is this normal?


----------



## dsrk

devin.oct said:


> Hello, anybody using MT-602?
> Mine does a popping sound on my HD6XX when turning off the amp, it is about a listening volume, volume knob is at zero and source is muted, no popping sound when turning on though.
> Anybody also experienced this? Is this normal?


It's normal, I hear the pop too every time I turn it off.


----------



## devin.oct

dsrk said:


> It's normal, I hear the pop too every time I turn it off.


Thanks, so is it better to unplug headphone first before turning off?


----------



## CADCAM

My 602 also has a nasty pop when you turn the unit off, I unplug my headphones every time I remember. I don't understand why this wasn't addressed by Xduoo during development/production of this amp. Long term affects of the pop and the extra unplugging and plugging of the headphones...


----------



## AudioCats

the little ta-26 looks interesting, does anybody know what kind of B+ voltage it is running at?

not a lot of space inside for upgrades though.


----------



## Wiljen

Barnold Schwarzenficker said:


> I recently purchased the MT-602 but noticed that the right tube (the smaller one) was not fully inserted into it's socket (the pins were showing) and that the tube was leaning to one side. I Removed the tube and indeed saw that one pin was bent. I contacted the seller and he provided me with a replacement. However that one too does not fully insert into the socket and from what I can see (photo's attached) one pin is preventing all the pins from being fully inserted and by now is probably bent as well.
> 
> I'm a complete novice when it comes to tube amplifiers but as far as I know the pins should not be showing.
> 
> ...


That is fairly normal - as long as it is making solid contact and sounds good (no cracks and pops like a sporadic connection will cause) I wouldn't worry about it.  You can spend a lot of time trying to get them to seat perfectly only to find out the glass jars are different heights (like my 604) and have it still drive you nuts to look at it.   It makes my OCD flare up for sure.


----------



## Wiljen

CADCAM said:


> While we're at it Wiljen do you think the 602 and HE400i would be a good pairing?



Should do just fine.  With the 602 being a hybrid it shouldn't have any trouble driving planars (within reason).


----------



## Wiljen

CADCAM said:


> I never tried the stock tubes but Wiljen might be able to chime in here and give an opinion...



I might try the Russian tube as it may be considerably easier to source in India than the Sylvania made tubes will be and the Soviet war-time production tubes were quite good as well.  Yes, I do think it makes a difference as the stock tubes showed fairly poor quality control in my experience.   Some are good, others not so much and there is no real way to tell other than to try.   With my 604, I got 2 different styles of tube (different bases and bottle heights) with 4 different overall heights.    They all worked, but that's about as positive a comment as I can make about them.   They are microphonic with one that really talks a lot.


----------



## dsrk

Wiljen said:


> I might try the Russian tube as it may be considerably easier to source in India than the Sylvania made tubes will be and the Soviet war-time production tubes were quite good as well.  Yes, I do think it makes a difference as the stock tubes showed fairly poor quality control in my experience.   Some are good, others not so much and there is no real way to tell other than to try.   With my 604, I got 2 different styles of tube (different bases and bottle heights) with 4 different overall heights.    They all worked, but that's about as positive a comment as I can make about them.   They are microphonic with one that really talks a lot.


Please give the model of the Russian tubes


----------



## Wiljen (Aug 7, 2021)

AudioCats said:


> the little ta-26 looks interesting, does anybody know what kind of B+ voltage it is running at?
> 
> not a lot of space inside for upgrades though.



I measured mine at 169V.    My DV336 measures at 142V by comparison.  The Crack has the highest at 186V.   For the record, the Ta-26 is the worst of the 3 to get inside to measure anything.  Definitely not DIY friendly.


----------



## Wiljen

dsrk said:


> Please give the model of the Russian tubes



They should be listed as either 6J1P-EV  or 6ZH1P-EV depending on the source and most were made at Voskhod.


----------



## AudioCats (Aug 7, 2021)

Wiljen said:


> I measured mine at 169V.    My DV336 measures at 142V by comparison.  The Crack has the highest at 186V.   For the record, the Ta-26 is the worst of the 3 to get inside to measure anything.  Definitely not DIY friendly.



Thanks!
is the filament supply AC? or DC? regulated? or not?  .


----------



## dsrk (Aug 8, 2021)

Wiljen said:


> They should be listed as either 6J1P-EV  or 6ZH1P-EV depending on the source and most were made at Voskhod.


Are these good enough to order? My headphones are HD6XX, Final E5000, FiiO EM5 and Moondrop Kanas Pro
https://www.ebay.com/itm/273238026793

or these
https://www.ebay.com/itm/184902428030


----------



## spookyshan

xduoo ta-30 is $600 on drop again I believe, really considering it for dt1990


----------



## Wiljen

AudioCats said:


> Thanks!
> is the filament supply AC? or DC? regulated? or not?  .





dsrk said:


> Are these good enough to order? My headphones are HD6XX, Final E5000, FiiO EM5 and Moondrop Kanas Pro
> https://www.ebay.com/itm/273238026793
> 
> or these
> https://www.ebay.com/itm/184902428030



Either pair should do well.


----------



## Wiljen

AudioCats said:


> Thanks!
> is the filament supply AC? or DC? regulated? or not?  .


I'll have to tear it down again and trace it all to be sure but I am thinking it is DC


----------



## dsrk (Aug 9, 2021)

Hi All,

I am not much of desktop user, so I don't have of any experience with desktop AMPs other than Schiit Magni 3+.

It's been more than a week and I am simply loving this tiny AMP MT-602. I did not expect this level of improvement over my XD-05 Plus with Burson V5i dual.
I always boost little bit of treble and bass with FiiO M11 Pro + XD-05 Plus + H6XX but with M11 Pro + MT602 I am just adding little bit of sub bass and I get much better dynamics and slam.

I had Magni 3+ for my HD6XX for while but I did not like the pairing much over XD-05+.

If anyone trying to get a budget AMP for HD6XX, look no further MT-602 is a fantastic paring with HD6XX IMO.

Now it brings me to these questions:
1. I am looking to upgrade, how much an improvement the bigger brothers ( TA-10R and TA-20) bring over MT-602?
2. Will adding a desktop DAC (like Topping E30) give any improvement to my current setup (FiiO M11 Pro line out to MT-602)?

Please advise.


----------



## Wiljen

dsrk said:


> Hi All,
> 
> I am not much of desktop user, so I don't have of any experience with desktop AMPs other than Schiit Magni 3+.
> 
> ...



The Ta-20 adds a bit of power and has more tube options so it can be made a bit warmer than the 602 can if using things like the Mullard 12au7 or the Amperex.  Having said that, I wouldn't expect night and day differences with the 602 vs the Ta-20 when using the HD6xx as it doesn't really need the additional power (as you've already found) and unless you go balanced the Ta-20 is likely mostly added cost rather than added improvements.

I would not expect the E30 to make a huge difference over the M11 pro either as both have similar DACs and capabilities.   I think the next step up would be something that is a bracket or two higher cost wise.    Something Like the RME ADI-2 or Denafrips is likely to be notably better but with costs pushing close to the 1K mark, they should be.


----------



## dsrk

Wiljen said:


> The Ta-20 adds a bit of power and has more tube options so it can be made a bit warmer than the 602 can if using things like the Mullard 12au7 or the Amperex.  Having said that, I wouldn't expect night and day differences with the 602 vs the Ta-20 when using the HD6xx as it doesn't really need the additional power (as you've already found) and unless you go balanced the Ta-20 is likely mostly added cost rather than added improvements.
> 
> I would not expect the E30 to make a huge difference over the M11 pro either as both have similar DACs and capabilities.   I think the next step up would be something that is a bracket or two higher cost wise.    Something Like the RME ADI-2 or Denafrips is likely to be notably better but with costs pushing close to the 1K mark, they should be.


Thanks for the reply.
Yes they both have AKM DACs but E30 uses 4493 and M11 Pro uses 4497.


----------



## Wiljen

dsrk said:


> Thanks for the reply.
> Yes they both have AKM DACs but E30 uses 4493 and M11 Pro uses 4497.


Most of the time I find the implementation to be far more critical than which chip is used as the RME uses an AKM chip too but resolves better than either the M11 Pro or the E30.   The Denafrips is a true ladder dac so isn't a chip based implementation and will have a different tonality than the AKMs typically do.


----------



## dsrk

Anyone tried these on MT602?
Riverstone Audio - Matched Pair (2 Tubes) JAN 5654W Fully-Tested Vacuum Tubes 6J1 / 5654 /6AK5/ EF95 / 6AK5


----------



## Wiljen

dsrk said:


> Anyone tried these on MT602?
> Riverstone Audio - Matched Pair (2 Tubes) JAN 5654W Fully-Tested Vacuum Tubes 6J1 / 5654 /6AK5/ EF95 / 6AK5



These are standard GE 5654W military surplus tubes.   They should work fine in the 602 but in my experience the GE are nothing particularly exciting about them.


----------



## dsrk

Wiljen said:


> These are standard GE 5654W military surplus tubes.   They should work fine in the 602 but in my experience the GE are nothing particularly exciting about them.


Oh ok, they are available on Amazon India. Thought they would reach me faster.

I now have to order on ebay which almost takes a month or more to reach me.

Thanks Wiljen.


----------



## dsrk

Wiljen said:


> These are standard GE 5654W military surplus tubes.   They should work fine in the 602 but in my experience the GE are nothing particularly exciting about them.


Which pairs best with HD6XX Sylvania or Russian tubes?


----------



## CADCAM

dsrk said:


> Which pairs best with HD6XX Sylvania or Russian tubes?


Out of my current crop my favorite is the 1969 Sylvania 5654, which I believe, (it's so hard to evaluate) sound superior to the 1967 Sylvania's that were my previous favorite. Either one sounds better than anything else I've tried which include the GE 5654. The only tube I haven't tried yet in my 602 is the Tung-Sol 6AK5W mainly because I'm not sure I'd be able to get it out, they are short!


----------



## CADCAM

Just got another pair of the 69' Sylvania's, these must have been sitting in the boxes since 69' because the boxes are like new except for fading from age and the tubes look new. Printing on tube was perfect but unfortunately the pins were very oxidized and no matter how careful you are some of the printing gets damaged during the cleaning process  you have to hold the thing to clean it!
Anyway... going to try them at home later on the MT-602 and hopefully they sound as fantastic as the last pair


----------



## Wiljen

AudioCats said:


> Thanks!
> is the filament supply AC? or DC? regulated? or not?  .



I got a thorough tear down and took some photos and on tracing the pins the Heaters are AC powered and not DC.  Glad I went back and checked because my initial thought was incorrect.

I'll post teardown shots in the review so you can see boards in them.


----------



## dsrk (Aug 15, 2021)

MT-602 pairs well with Ananda, I like it better than HD6XX + MT-602.


----------



## tkddans (Aug 18, 2021)

Just got a MT-604 review unit from Apos, a loaner I have to give back, and I’m honestly getting strong out of the box impressions with sound quality.

Plus, it doesn’t hurt that they have a very pleasant color coming through the tubes more than the TA-30 I have, at any angle I try to look between the two. Now, I do wonder if that glow is purely due to lights installed, and not actually tubes warming up (since, when I turned on the 604, the orange light was IMMEDIATELY brightly glowing; and tubes need time to warm up and glow brighter, in past experiences with my TA-30). Or maybe the filaments are just genuinely glowy? I gotta switch tubes to see what happens, but I think it’s just lights. Still very pretty!











I normally use a Xduoo TA-30 ($700 retail, often $600 on Drop), so my point of comparison is pretty strong already. Not to mention, my TA-30 has maybe $100 or more of tube replacements.

And yet, even before tube rolling the 604, I’m almost not inclined to bother switching them out to say that I enjoy what I get from it. And the thing is only what…$170? I gotta check the site for price again but I think that’s right (I’m on my phone and lazy right now ok?!) haha

I was only going to make an impressions video, but now I feel I have to record full fledged demos of the 604 with stock tubes, my TA-30 with my favorite tubes, and the 604 with those same favorite tubes. I gotta share sound samples in a video so people can hear for themselves what I’m hearing - that is, this cheap  entry level priced tube amp may just be the best bang for the buck.

The only caveat may be, and I haven’t discovered yet if this is true, that the 604 may not respond to tube rolling as noticeably as the TA-30, because the 604 is not a full tube amp but a hybrid solid state and tube. Amps with solid state components are said to be less “tubey” than pure tube driven gear.

More thoughts to come in an official video review with demos!!

EDIT: Just occurs to me that my other tubes are too big, I think, for the 604. Does anyone have recommendations for these smaller tube slots?


----------



## jsmiller58

tkddans said:


> Just got a MT-604 review unit from Apos, a loaner I have to give back, and I’m honestly getting strong out of the box impressions with sound quality.
> 
> Plus, it doesn’t hurt that they have a very pleasant color coming through the tubes more than the TA-30 I have, at any angle I try to look between the two. Now, I do wonder if that glow is purely due to lights installed, and not actually tubes warming up (since, when I turned on the 604, the orange light was IMMEDIATELY brightly glowing; and tubes need time to warm up and glow brighter, in past experiences with my TA-30). Or maybe the filaments are just genuinely glowy? I gotta switch tubes to see what happens, but I think it’s just lights. Still very pretty!
> 
> ...


Definitely LEDs under the tubes, but looks great!

This link gives some suggestions for tubes - https://audiofool.reviews/tube-rolling-the-xduoo-mt-604/


----------



## CJG888

tkddans said:


> Just got a MT-604 review unit from Apos, a loaner I have to give back, and I’m honestly getting strong out of the box impressions with sound quality.
> 
> Plus, it doesn’t hurt that they have a very pleasant color coming through the tubes more than the TA-30 I have, at any angle I try to look between the two. Now, I do wonder if that glow is purely due to lights installed, and not actually tubes warming up (since, when I turned on the 604, the orange light was IMMEDIATELY brightly glowing; and tubes need time to warm up and glow brighter, in past experiences with my TA-30). Or maybe the filaments are just genuinely glowy? I gotta switch tubes to see what happens, but I think it’s just lights. Still very pretty!
> 
> ...


Isn’t the TA-30 a hybrid too?


----------



## tkddans

CJG888 said:


> Isn’t the TA-30 a hybrid too?


Oh you’re right! Silly me 

but it does have a rectifier tube and the transformer in the back. I’m not an expert on how the circuitry differences play out exactly, etc etc.; though would it be true that the addition of the large transformer and rectifier in the circuit path mean that there could be more opportunity for sound to be affected by those additions to the unit, compared to the 604?

I wish I had smaller tubes to roll out with the 604 and see how much different I could make the sound appear.

I know that with my TA-30, I hear the sound change between tubes quite audibly. But with the 604, I can’t say right now since I don’t have the tubes to try.

I just assumed that the additional components on the 30 meant for greater leeway for rolling and for different experiences, but hey I don’t actually know for sure if it’ll be so different than what’s possible on the 604 without rectifier and transformer.

Thanks for pointing it out!


----------



## AudioCats

Wiljen said:


> I got a thorough tear down and took some photos and on tracing the pins the Heaters are AC powered and not DC.  Glad I went back and checked because my initial thought was incorrect.
> 
> I'll post teardown shots in the review so you can see boards in them.



Thanks. Any idea what the heater voltage is?


----------



## Wiljen

AudioCats said:


> Thanks. Any idea what the heater voltage is?


mine measures at 6.26-6.28V when in operation.   Had to wire an adapter to get a multimeter on the pins.


----------



## AudioCats

Thanks. 
That is perfect filament voltage, wow.


----------



## AudioCats (Aug 24, 2021)

ta-26 is now on sale, 10% off. 
$287 is still a good chunk of change, though.


----------



## Wiljen

AudioCats said:


> Thanks.
> That is perfect filament voltage, wow.


Yeah it seems to be a pretty well designed amp from the measurements.  It won't please the DIY crowd at all as the crack and DV336 are much easier to tinker on, but it does provide a finished product for less $ than a crack that comes closer to rivaling the finished crack/speedball than the DV does without pushing the price to double that of the base model.


----------



## AudioCats

the TA26 enclosure is a bit on the narrow side but workable.  If it is 1" wider that would be perfect. Tube combination is good, and the metal case helps heat dissipation.  

I am mainly curious of whether (after removing the output capacitors) there will be enough room in the TA26 for HV regulation (heat dissipation ~ 3w), filament power management, and maybe even CCS for output (replacing the 1k resistors). 

BHC and DV enclosures are larger, but still not big enough. To do it right, output capacitor banks will need to be in a separate box anyway.


----------



## Wiljen (Aug 25, 2021)

AudioCats said:


> the TA26 enclosure is a bit on the narrow side but workable.  If it is 1" wider that would be perfect. Tube combination is good, and the metal case helps heat dissipation.
> 
> I am mainly curious of whether (after removing the output capacitors) there will be enough room in the TA26 for HV regulation (heat dissipation ~ 3w), filament power management, and maybe even CCS for output (replacing the 1k resistors).
> 
> BHC and DV enclosures are larger, but still not big enough. To do it right, output capacitor banks will need to be in a separate box anyway.



Its going to be a tough case to work in as there isn't much room.  I suspect any major upgrade is going to require case replacement as part of the process.


----------



## AudioCats (Aug 25, 2021)

wonderful pictures! Thanks.

so the bottom board is dropped by quite a bit (top board is about even with 220uf/250v kgx caps, so about 1.2")

Does the bottom board slide into some kind of grooves inside the case?


----------



## Wiljen

AudioCats said:


> wonderful pictures! Thanks.
> 
> so the bottom board is dropped by quite a bit (top board is about even with 220uf/250v kgx caps, so about 1.2")
> 
> Does the bottom board slide into some kind of grooves inside the case?



The board rides in slots milled into the case sides.


----------



## AudioCats

Are there other such slots in the case to allow the board to go up by about 3/4"?


----------



## Wiljen (Aug 26, 2021)

AudioCats said:


> Are there other such slots in the case to allow the board to go up by about 3/4"?


No, there is one additional that might net 1/4" tops but even then you'd need to replace the front and rear faceplates as the pot and RCAs would have to be lowered if the board were moved up and that would mean cutting the board to allow for it.


----------



## tkddans (Aug 26, 2021)

My review is still processing, but I'm about to sleep and want to share this haha. Enjoy the review of the Xduoo MT-604 ($170) with a sound demo of it, along with comparisons with the Drop THX 789 and the Xduoo TA-30 ($700).

To sum up, I totally recommend going cheaper if your only priority is sound quality. Because...I cannot tell the difference between the two amps (apart from the more expensive TA-30 having more rolling potential since it has a rectifier while the 604 does not).

If you want bluetooth or filter adjustments, or a pre-existing tube collection that fits the larger sockets of the TA-30, then you may still prefer the TA-30.

Big caveat though with the cheaper 604, it has independent R/L channel volume knobs. So, that can be better or worse for you if you are ok adjusting them independently to adjust your volume. On the plus side, it means you can fix any channel imbalances your gear may have!


----------



## AudioCats

Wiljen said:


> No, there is one additional that might net 1/4" tops
> ...



good to know, thanks. 
So no real way to get extra space under the bottom board. I was hoping if it can go up 3/4", then the switch and connectors can flip from above the board to below the board (they will likely be upgraded anyway, which usually means chassis-mounted stuff off the PCB). No such luck.


----------



## S Crowther

tkddans said:


> My review is still processing, but I'm about to sleep and want to share this haha. Enjoy the review of the Xduoo MT-604 ($170) with a sound demo of it, along with comparisons with the Drop THX 789 and the Xduoo TA-30 ($700).
> 
> To sum up, I totally recommend going cheaper if your only priority is sound quality. Because...I cannot tell the difference between the two amps (apart from the more expensive TA-30 having more rolling potential since it has a rectifier while the 604 does not).
> 
> ...



Any sign of a replacement for the  TA-20? Amp only and fully balanced design.


----------



## tkddans

S Crowther said:


> Any sign of a replacement for the  TA-20? Amp only and fully balanced design.


Though I haven’t tried the TA-20, my experience here with the MT-604 and TA-30 tells me I could likely be happy with any Xduoo.

The differences between those two devices, one low cost and one high cost, came more down to features and degrees of play with tube rolling - more than differences in sound, for which I heard practically none on the tubes I had in.

Everyone’s ears are different, and tubes they own, but I would recommend getting the TA-20, or TA-30, or 604 for their feature differences and not the expected sound differences.

Like, do you want bluetooth? Do you want the chance to play with swapping out the large rectifier tube available on the TA-30? Do you want independent channel control (604)? Or do you simply prefer the aesthetics or form factor of one or another?

That’s my personal take on how to approach Xduoo amp choices at this time.


----------



## AudioCats

Wiljen said:


> Its going to be a tough case to work in as there isn't much room.  I suspect any major upgrade is going to require case replacement as part of the process.



any idea how hot those two front electrolytic (C1 and the one next to it) get, after running the TA-26 for a few hours?


----------



## Wiljen

AudioCats said:


> any idea how hot those two front electrolytic (C1 and the one next to it) get, after running the TA-26 for a few hours?


no, I can't speak to that as the board does not lend itself to running it outside the case for any extended length of time as it doesn't have adequate support or stand offs.   I suppose you could rig some form of test frame but I have not gone to that length to date


----------



## AudioCats

what I meant was "how hot will C1 get when in the enclosure".
If your multi-meter has a temp probe, try touch the tip of probe to the cap and take a reading? maybe through the side vent holes or through the power tube opening above.

 The cap temp can tell a lot about how long the caps will last.  KXG series is rated 10000hr at 105C.

There is not much to go wrong in this type of amp, one main weak link being the electrolytic cap.


----------



## jsmiller58

My MT-602, purchased the last week of March from Apos, is now quite dead - will not power up.  Anyone else experience this, and if so, what did you do?


----------



## Slim1970

jsmiller58 said:


> My MT-602, purchased the last week of March from Apos, is now quite dead - will not power up.  Anyone else experience this, and if so, what did you do?


I have the MT-604 and so far so good.


----------



## jsmiller58

Slim1970 said:


> I have the MT-604 and so far so good.


I have the 604 as well, and no problems so far either.  

My 602 did not get much use so I was surprised today to find it had failed.  Turned it on, it got a bit warm and also smelled strange, so most likely an electrical short.


----------



## Slim1970

jsmiller58 said:


> I have the 604 as well, and no problems so far either.
> 
> My 602 did not get much use so I was surprised today to find it had failed.  Turned it on, it got a bit warm and also smelled strange, so most likely an electrical short.


Dang, sorry to hear that. I want some more resolving tubes for my MT-604. I was doing some listening on the MT-604 with my Abyss TC's and the sound wasn't that bad. It's just lack some resolution and midrange clarity. I think with better tubes it can be a pretty good performer.


----------



## Athur126

Trying to decide between the TA10R and TA03S to pair with my Hifiman Ananda/DT880s. The shop I went to didn't have either model on demo but I managed to try the HM602 with a Topping DAC and quite enjoyed that. Any recommendations?


----------



## FyxeHexyz

Greetingsss~ I currently have a XA-10. Is there any difference in sound between the Single-Ended and Balanced ports? I don't have a Balanced cable to try it out myself so I would like to get an input about it.


----------



## dsrk

FyxeHexyz said:


> Greetingsss~ I currently have a XA-10. Is there any difference in sound between the Single-Ended and Balanced ports? I don't have a Balanced cable to try it out myself so I would like to get an input about it.


Yes, more power and dynamics.


----------



## Dobrescu George

If you need a nice headphone amplifier with Tubes, Xduoo could have the answer! 

The one amp I am reviewing today is from their entry-level line, and it uses many tricks to reach our ears, it ain't perfect, but at 100 USD nobody expects perfection. 

It delivers well on the sonics, if you have a separate DAC already, and is light, plus it has some of that tube magic, but more info in my full written review about it ~ 

https://www.audiophile-heaven.com/2021/09/xduoo-mt-602-tube-headphone-amp-freak-trickster.html


----------



## YanaMJ

I'm considering buying a TA-20 and I'd like to roll the tube but I'm lost...


----------



## YanaMJ (Sep 15, 2021)

Dolores Dolomites said:


> Hello everyone!
> Sow-uh... I've only just slipped into the rabbithole along with the bloody apneademic so I'm by no means experienced yet, especially on tube amplifiers!
> I've got the TA-20 on sale on BF because I wanted to start digging tube sound, but I really don't know where to start from with so many tubes to choose from...
> 
> ...


I'm exactly in the same situation and I like to know where to buy decent tubes in EU...


----------



## Silver Wolf

YanaMJ said:


> I'm considering buying a TA-20 and I'd like to roll the tube but I'm lost...


It all depends on if you want to try new current tube, NOS or used old stock, here's a link on basic rolling and differing types of tubes.

https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/

I'm currently enjoying some British NOS Brimar, as to where to buy tubes well online there are all sorts of places. I've bought mine so far just via eBay or online stores.


----------



## 9leonn

I’ve just bought a used ta-20, which sounds really great (first tube amp for me).
There’s just an annoying imbalance with the XLR output, left channel being louder. It gets me crazy!
Since warranty is expired, Audiophonics won’t repair it or help to send it back to XDUOO, 

I’ve tried all cables, sources, switch tubes, etc. But no,result…

Have any of you experienced this and solved the issue?


----------



## Slim1970

Anyone looking for a MT-604, I have one listed in the classifieds:

https://www.head-fi.org/classifieds/xduoo-mt-604.11393/


----------



## wakokokoyz

hi all.
question; 
i have mt602 volume somewhere between 9 and 11 o'clock as normal listening volume. if i change to ta26, will i be utilizing it with less that of mt602? considering all to be same (source and headphones). i worry ill be stuck to volume below 9 o'clock. any input will be gladly appreciated. cheers!


----------



## asarkhentamentiu

Athur126 said:


> Trying to decide between the TA10R and TA03S to pair with my Hifiman Ananda/DT880s. The shop I went to didn't have either model on demo but I managed to try the HM602 with a Topping DAC and quite enjoyed that. Any recommendations?


Were you able to audition the TA03s and the Ananda? That amp also caught my eye, but I keep reading how supposedly the two are incompatible


----------



## Busyman201

ta-26/ or mt-604 for hd600/hd800?


----------



## CJG888

TA-26!

300 Ohm headphones are a perfect match for an OTL amp. They will benefit far more from this than from balanced operation.


----------



## toodles1978

What would be the best suggestion for the kennerton magni?


----------



## jonathan c

CJG888 said:


> TA-26!
> 
> 300 Ohm headphones are a perfect match for an OTL amp. They will benefit far more from this than from balanced operation.


Mmm…mmm…Senn HD600…ZMF Atticus / Auteur / Aeolus / Eikon / Verite…


----------



## cirodts

I bought an xduoo ta-20, but it turns on and off only with the switch on the back or is there a way to put it in stand-by?


----------



## BadgerRivFan

cirodts said:


> I bought an xduoo ta-20, but it turns on and off only with the switch on the back or is there a way to put it in stand-by?


I also have a TA-20 and the short answer is “no.“  You would always want to turn it off anyway in order to save the life of your tubes.


----------



## hmscott (Nov 10, 2021)

cirodts said:


> I bought an xduoo ta-20, but it turns on and off only with the switch on the back or is there a way to put it in stand-by?


Nope, it's a bit annoying at first, but after 1+ years of enjoying the TA-20, tube rolling, and going back and forth between it and my Topping A90, I only listen with the TA-20.

Keeping AC away from the headphone ports on the front panel and the electronics in between the back and front panels is a good idea anyway, and adding indirect switching / relay would add another circuit and introduce another point of failure, not to mention costing more to implement either way.

A lot of devices do this, keeping the AC in the back by keeping the on/off switch and Fuse in the back next to where the AC comes in.

Also, stand-by would add still more cost, and with Tubes you need to keep the heaters running - you don't want them to cool down - so IDK how much standby would help.

You could set up a power strip on your desk and switch off the TA-20 with that power strip power switch, or some other indirect way of controlling the power to the TA-20 via a switch more convenient to your reach.

Update: Here's a bonus idea, I have used LAN connected power strips for decades professional in data centers, and now they are getting cheap enough for consumers, I've not tried any of these so do your own homework as to their viability for your needs:
https://www.amazon.com/Web-IP-Power-Switch/s?k=Web+IP+Power+Switch

For each power socket you label the device info in the configuration, then you can control to your devices via a browser, and potentially automate their power cycles. The professional controllers provided power usage, voltage tracking, along with temperature monitoring.


----------



## Wiljen

cirodts said:


> I bought an xduoo ta-20, but it turns on and off only with the switch on the back or is there a way to put it in stand-by?



Nope, no standby mode.  Tubes generally need 15-20 minutes to fully come up to heat and do their best work so I just leave my tubes on unless I am going to be away for an extended period.


----------



## cirodts

thanks for the answers, it was just curiosity, a little patience for the accent but the sound is fantastic.
I had topping A90 and I say that the ta-20 beats it in separation clarity and sweetness of sound, I never liked the A90, it has a too lean and sometimes fatiguing sound.
why the trigger relè is delayed at the ignition?


----------



## hmscott (Nov 10, 2021)

cirodts said:


> thanks for the answers, it was just curiosity, a little patience for the accent but the sound is fantastic.
> I had topping A90 and I say that the ta-20 beats it in separation clarity and sweetness of sound, I never liked the A90, it has a too lean and sometimes fatiguing sound.
> *why the trigger relè is delayed at the ignition?*


To give the Tube heaters a minimum time to warm up to avoid in-rush current induced audible "pops" and "weak/static" sound out of the cold tubes.

The TA-20 delay timeout is calibrated to 12AU7, but I've had no problems with 12AT7/12AX7 class tubes and equivalents.

The E80CC's take longer to heat up and they can cause the TA-20 Protect to light up and block audio on the first cold power on.  After the 2nd power on with average ambient temperatures the E80CC's will be hot enough to run, when it is cold in the room it can take 3 power on's to get the E80CC's hot enough to turn on the relay. 

A neat trick I found was the leave my A90 (sitting under the TA-20) powered on to "pre-heat" the TA-20 and therefore the E80CC's ambient temperature, and even in cold weather the TA-20 / E80CC's turn on the first time.


----------



## cirodts

hmscott said:


> To give the Tube heaters a minimum time to warm up to avoid in-rush current induced audible "pops" and "weak/static" sound out of the cold tubes.
> 
> The TA-20 delay timeout is calibrated to 12AU7, but I've had no problems with 12AT7/12AX7 class tubes and equivalents.
> 
> ...


Nice tactic of staying on at 90, which tubes would you recommend for the best sound quality?
maybe if they are on amazon it is better.


----------



## hmscott (Nov 11, 2021)

cirodts said:


> Nice tactic of staying on at 90, which tubes would you recommend for the best sound quality?
> maybe if they are on amazon it is better.


Well, that is a tough question to answer as there are a seemingly infinite number of makes/models/factories/years/variations out there, and availability is roughly unreliable for the most sought after tubes - especially for reasonable prices - to really give a definitive answer.  But, I'll try to share some things I've learned and tried, from experience.

I can give you some suggestions to start, but it is a personal journey only limited by your curiosity and willingness to read up about purchases before buying, and read up on sources before you buy - comments and reviews help, but first hand experience is what sticks with you as a guide over time.

I wouldn't blow a lot of money on NOS tubes to start - New Old Stock - even though that is where I found the best sound, tubes from the 50's, 60's, and some into the 70's, I did start with Current Manufacture 12AU7/12AT7 tubes from China, Russia, etc.

For the TA-20 I'd recommend 12AT7/ECC81/6060/6201 and similar 12AT7 family tubes. The 12AU7's are great sounding too, but I enjoy the sound of the 12AT7's more in the TA-20 specifically, and I haven't found a 12AU7 tube that I prefer over my favorite 12AT7's.

Here are the best sounding 12AU7's I've found:
Tung-sol 12au7 Black Glass

The problem with buying NOS tubes is that some sellers on eBay consider used tubes that measure within a 85%-90% range "NOS", and NIB or New in Box tubes as the unused tubes.  So be certain to buy 100% Life Remaining new tubes from whatever era.

I did get some of those "semi-used" tubes to try as they shaved off some cost, and I found if you only use "Over-the-Ear" headphones and don't use IEM's these "Semi-Used" tubes may be great.  But, I've found tubes start to show stronger and stronger HISS in IEM's when they are under 95%  Measured Life Remaining.  Starting at 95% and less Life Remaining I can start to detect HISS.  HiSS doesn't get in the way of listening to music on IEM's until under 90%, but that likely varies.  Best to stick to 100% Life Remaining - unused actual New tubes.

Reading up on all of this before I ordered the TA-20, I ordered a selection of Current New Manufacture 12AU7 tubes, mostly Chinese and Russian tubes that are 100% new, and I found they actually sound great-  better than the included pair of 12AU7s that come with the TA-20.

I've found tubes I really enjoy more since, and when I find those tubes now I buy a backup pair right away - specific make/model/datecode tubes are often hard to find - you have to hunt for them for a while to find them, so be patient - that is why I bought the Current Manufacture pairs from Amazon, eBay, and AliExpress so I could listen happily while hunting for 100% Measured Life - New In Box examples of the tubes I wanted to try.

Starting out, I really liked the PSVANE series of tubes, especially the PSVANE 12AT7T MKII's, but PSVANE has stopped making those.  PSVANE has released their new 12AT7-S Art Series which also sound great - but I can't find them for sale on Amazon right now - where I originally bought both series:
https://www.amazon.com/Matched-Psvane-12AT7-T-Vacuum-Premium/dp/B00N4S3DYU <= Unavailable, and I only have 1 pair myself...
https://www.amazon.com/s?k=psvane+12at7-s+tubes <= the listing I bought from is gone, and no other listings exist right now on Amazon
https://www.amazon.com/s?k=psvane+12au7-s+tubes <= This would be a good starter tube too, I started with the PSVANE 12AU7-T MK II and PSVANE 12AU7-S, before I asked Xduoo if the 12AT7's were compatible, to which Xduoo replied that the TA-20 would also run the 12AT7 and 12AX7, but we both found the 12AX7 too "hot".

It looks like you would need to buy direct from China companies right now for the PSVANE 12AT7-S Art Series, which I've also done from AliExpress, but some of the PSVANE Chinese distributors also list on eBay, and ship from China:
https://www.ebay.com/sch/i.html?_nkw=PSVANE+12AT7-S

I buy NOS-NIB 100% tested/measured remaining Life tubes from eBay and from other shops online, and although I can recommend a few reliable sellers, they each don't always have stock that I want to buy at any particular instant in time.  Sometimes they will get a bunch in stock, and then their inventory may be "dry" for months.

So, let me see, how about I focus on recommending a pair of NOS tubes I bought recently (last 6 months) - these two are the same tube from 2 different decades, and the newer one measures quieter, but I started with the older set (Quad) first:

RARE Matched Pair NOS/NIB Mullard GEC/B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958 <= currently #3 in my list
RARE Matched Pair Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes 1968 <= next on my list

There really aren't any others on Ebay - via quick look - right now that I'd be able to recommend at or under $100/pair, so maybe focus on a few pair of Current Manufacture Tubes, I can recommend the PSVANE, Telefunken, maybe recent Genalex and Mullard, and get one great pair of NOS tubes to start.  I can tell you that I wasn't as happy with the JJ Electronics, Electro-Harmonix, but there are people that review those and love them, so it is all down to personal taste.

GE 6201's sound great and are inexpensive (and expensive, depending on the age), and here's one that looks like a good candidate.  It is a bit pricey, but I've also seen these made in France go for $199/pair.  I've bought from overseas a few times and the only thing is they take a long time to get here (USA), and shipping can be pricey if you want to get them quicker:
General Electric USA matched pair NOS 6201 tubes ECC801S 12AT7 ECC81 NIB

A few other observations:

Tubes made for the Military/Laboratory/Medical/Aero will often be better made with longer rated lifetimes.  As tubes become more desireable they become outragously expensive, so I try to find the best reviewed tubes that are at or under $50/tube at most.  Reliable operation, mechanical silence, and even the sweetness of the sound comes down to the ruggedness of the build of the tube.  Copper Rods Holding the layers rigid, Double or Triple Mica layers, shapes - sizes - count of the "getter" will affect the sound.  Gold pins - kept corrosion free - will help keep your tube sockets clean and easy to insert/remove tubes - I don't put dirty pinned tubes into the socket - I clean the pins first, or even reject the tubes if they are bad enough.

Which brings up another important thing to look for when picking a dealer/seller, make sure they have at least a 14 day return period.  I stay away from the sellers on eBay that don't accept returns.  I've only returned 2 orders over time, and I wouldn't have been stuck for much if they didn't let me return them, but good dealers will want to get feedback on what went wrong with their tubes.  One set failed in the TA-20 - protection lit up right away.  The other set had pins that were so corroded - they were gold pins but in the photo's they looked like steel pins.  It's not so bad buying on eBay if you can make a return.

Someday if I get the energy and focus together I may write up each of the tubes I've tried, what they sound like to my ears in the TA-20, how they compare to others in the list, where I found mine and where I've seen them lately, and perhaps come up with some order of recommendation... someday


----------



## CJG888

RFT NOS tubes are also good value, as are Ei. These were generally made on Philips or Mullard production lines which had gone East…


----------



## CJG888

I  extremely happy with a bunch of NOS Ei ECC83 which I bought for a few quid back in the 90s.


----------



## hmscott (Nov 11, 2021)

CJG888 said:


> RFT NOS tubes are also good value, as are Ei. These were generally made on Philips or Mullard production lines which had gone East…





CJG888 said:


> I  extremely happy with a bunch of NOS Ei ECC83 which I bought for a few quid back in the 90s.


I don't think I've ever seen "EI" tubes, do you have some links/examples?  Ahh, found a couple Used:
https://www.ebay.com/itm/124907188528
https://www.ebay.com/itm/124907187110

I've seen RFT tubes a number of times, but haven't learned much about them - not enough to pick a winner with some measure of certainty.

I've bought a few rebadged tubes - like Haltron E80CC's - which were originally either Tungsram or Philips made, the E80CC's of an era all look pretty identical in material and manufacturing.

The Czech manufacturing - like Tesla ECC802s/ECC802s/ECC803s - I've heard are sweet when you can find actual real examples - I heard there were / are a lot of Tesla/Telefunken fakes at some points in the past.  I may jump in and get some NIB Tesla Yellow ink labeled from the 60's next time I see them for sale.  The Telefunken ECC802s/ECC802s/ECC803s from the 60's are too expensive.

There are tube collectors that will pay for rarity - higher prices don't always equate to "best" sound for your own tastes, you may find $400/pair tubes you wouldn't enjoy, so that is why I keep to the $50/tube max spend.  You can also save per tube by buying in quantity, but it doesn't make sense to acquire boxes of tubes unless you want to go into the tube reselling business, or belong to an active community of traders - welcome to the pandemic... I've noticed tube inventories are pretty stagnent right now.  Not like it was before the pandemic.

What are you using right now in your Xduoo amp?

I'm listening right now with Brimar 6060s, I had the Mullard CV4024's running for weeks before those, I am partial to the 12AT7 sound.


----------



## cirodts

Thanks then I will read very carefully later because there is a need for attention.
How many hours of burn-in does the TA-20 need?
What improves after burn-in


----------



## hmscott (Nov 11, 2021)

cirodts said:


> Thanks then I will read very carefully later because there is a need for attention.
> How many hours of burn-in does the TA-20 need?
> What improves after burn-in


All tubes need initial power on warm up time to stabilize, that is why the TA-20 doesn't immediately pass signal.  You can get pops and clicks and warm up anomalies in the amplification during the initial in-rush of current and subsequent warm up to stabilized temperature.

The TA-20 recesses the tubes into the case which I think helps it all come to equilibrium temperature quicker.  In practice, I don't find any of the tubes I enjoy need much warm up if the ambient temperature is 68F-73F.  They start out sounding good, and any improvement is small enough.  Tube testers have a heater warm up time before the test results are valid, a few minutes is usually enough, they measure with stable readings when at the equilibrium temperature, watch the meter needle or digits come to rest on a stable reading.

New tubes - as in never used - change how they sound to me over a wider range of time, some sound fine right away and some take a good 20+ hours and as much as 100 hours - but after that if you aren't enjoying them file them away to trade with someone that does enjoy them - through their own testing they may find that tubes sound profile fits their music or taste, even if you don't particularly enjoy them.

As 100% New out of the box the base characteristics of the tube - tonality, sound stage, air show from the start - if there is any harshness or sharpness that can reduce over time - usually 40 hours is enough.

When I cycle tubes out in rotation - I try to swap tubes every few weeks - and move to a known good pair again for a while and then go back to that new pair to get a fresh listen - I find the positive and negative characteristics I remember when I put them away are still there.  I find myself looking for certain pairs to listen to and others don't get much time.  I have 5-8 pair in rotation I enjoy, but recently that's circled around 3 pairs.  I have 2 pairs that sound great of each of those tubes, and so I have thousands of hours of great listening set aside, and far more with the wider circle of tubes I enjoy.

I am pretty much at the end of the hunt for tubes I "need", at least of the 12A_7 variety, I don't feel the need to find better tubes right now, I think I have enough.

But, I still read and learn, and I still have a list I am watching out for at a good price, but I'm not in any rush of need at this point.  That took about a year or so for me.


----------



## cirodts

is there a lot of difference in sound when changing tubes?
is it worth changing?


----------



## cirodts

As a DAC I have a gustard x16 and as an amp I have a loxjie p20 with ge5670 tubes and ifi power 12v and it is very good for the money, but the TA-20 already with the standard tubes is on another level, I'm happy.


----------



## HTSkywalker

cirodts said:


> is there a lot of difference in sound when changing tubes?
> is it worth changing?


YES and YES 🙂


----------



## Silver Wolf (Nov 11, 2021)

Rolling or trying other tubes is purely a personal/subjective thing so while folks may be able to make some random suggestions the best gear is your own ears for finding your own tastes. The differences vary depending on the tubes and from person to person, I got stuck on a set of British 1960's Brimar's and have several still to try but have just sat using these as I enjoy them.

So the other thing I can offer is if you are already happy with how the OEM tubes sound why change? Just enjoy, "it's all good" if you get bored at some point worry about opening cans of worms up then.

Just thought I'd share this pic as I'm wearing/using the T60RP on the xDuoo TA-20 today/right now in fact and it powers the hungry T60RP's fine, great combo. Who say's tubes and planar's don't mix ????? I'm really enjoying them.


----------



## hmscott (Nov 11, 2021)

cirodts said:


> is there a lot of difference in sound when changing tubes?
> is it worth changing?


You'll need to decide that for yourself.  If you notice a difference, one you enjoy more over another, then yes I find the tubes I enjoy have a wide, deep and tall sound stage.  Moving around in the top 3 the Brimar 6060's have a more full pleasing sound to me, and a wider - beside and behind the ears sound stage - that sounds more "real" to me, and is striking enough that I often need to pull off the headphones to tell if outside sounds are what I am hearing, or if the environment being mixed into what I am watching or listening to is the source of the "realism".

With those 3 pairs, Brimar 6060, Mullard M8162 (12AT7WA, CV4024), and Haltron E80CC they are similar but different enough to me that I can enjoy the changes between them.

If the E80CC's didn't run so hot - they use 2x the heater current and make the TA-20 run "hotter" - I'd probably just burn through the 5 pair of those I have.  I thought the Brimars and Mullards gave me a wide sound stage, but the E80CC's make a surprisingly stark improvement to my ears, the E80CC's focus all the sound sources in the mix for me to the point I would keep listening to them, but I think I need a backup TA-20 just in case the high heat takes a toll on my single unit.  So I rotate in the other wide sound stage tubes I enjoy - to keep my single TA-20 running longer.

But, I could also pick another 3 pair out of the others I have boxed up and enjoy those too.  The more enjoyable sounding - interesting sounding? - it doesn't mean more "accurate" but perhaps more "realistic" sounding to my ears, especially considering our methods of storage and presentation (speakers/headphones), so find what pleases you to listen to at the time and enjoy it.

I don't worry about how someone else is going to judge my enjoyment because our paths of experience are all very different, far more varied than are the shared same experiences.

If you do the same things all the time, you start to notice things, you become sensitive to differences if you pay attention.  I was fortunate in that I began listening to radio signals with headphones when I was 7 or 8, and got my Amateur radio license when I was 12, and participated in competitive CW contests until just before High School when I started working and didn't have much free time, but those early days of picking out weak signals, trying different headphones and amplifiers in and added on to existing radios, filters and equalizing the audio to best get the edge on hearing faint signals, still sticks with me today.

I have to bear the burden of my experience, but if you don't hear a difference, don't sweat it, it may come to you over time and it may not - either way enjoying the music doesn't often require those last smidgens of differentiation in the audio.


----------



## cirodts

oh


hmscott said:


> You'll need to decide that for yourself.  If you notice a difference, one you enjoy more over another, then yes I find the tubes I enjoy have a wide, deep and tall sound stage.  Moving around in the top 3 the Brimar 6060's have a more full pleasing sound to me, and a wider - beside and behind the ears sound stage that sounds niew "real" to me, and is striking enough that I often need to pull off the headphones to tell if outside sounds are what I am hearing or if the environment being mixed into what I am watching or listening to is the source of the "realism".
> 
> With those 3 pairs, Brimar 6060, Mullard M8162 (12AT7WA, CV4024), and Haltron E80CC they are similar but different enough to me that I can enjoy the changes between them.
> 
> ...


thanks for the advice of these valves rimar 6060, Mullard M8162 (12AT7WA, CV4024), and Haltron E80CC.


----------



## hmscott (Nov 11, 2021)

cirodts said:


> oh thanks for the advice of these valves Brimar 6060, Mullard M8162 (12AT7WA, CV4024), and Haltron E80CC.


There are lots of other great sounding tubes out there, I wouldn't focus your search too early except to use them as a starting point for your own discoveries.  You may like other tube characteristics more than the ones I enjoy, you won't know for sure until you actually take the time to listen.


----------



## marbert

SoundGuru said:


> This amp is still really powerful for 200 mW, and I need to turn my source to 20/100 in windows to get the volume to 9 o clock. This sound is less in your face and probably a better pair with Grado than the 602



Hello, do you still like xDuoo MT-601 as an amplifier for Grado? During this time did you find any problems or minuses in MT-601?


----------



## cirodts

Which tube has the fullest and deepest sound?


----------



## S Crowther

cirodts said:


> Which tube has the fullest and deepest sound?


----------



## SoundGuru

marbert said:


> Hello, do you still like xDuoo MT-601 as an amplifier for Grado? During this time did you find any problems or minuses in MT-601?


For me it sounded pretty good with the Grado as it has a more laid back sound, and had a better synergy compared to MT-602 (way too powerful and has volume channel imbalances at low volumes with low impedance headphones like Grado). For some reason the MT-601 was picking up some background noise. I moved it to another part of my condo where this noise has reduced, and I sometimes use it for listening.

If it wasnt for the noise problem, I would use it much more. I contacted the seller and they said it might be the power supply. I ended up changing the tube to Phillips NOS and this did not fix the problem. I thought it was the power so I also invested in a conditioner, that did not fix it either. The 601 also gets quite hot.

The MT-602 is dead quiet for comparison.

I am not sure if my unit was an outlier or if others have had similar problems....


----------



## cirodts (Nov 12, 2021)

Many thanks, interesting.
I am not an expert but I see many different abbreviations and numbers to characterize the tubes, how do I understand which tubes are suitable for the TA-20?


----------



## cirodts

with xduoo TA-20 c there is a big difference between listening with balanced and unbalanced inputs.
In balanced there is more power, soundstage and detail, a delight.


----------



## marbert

SoundGuru said:


> For me it sounded pretty good with the Grado as it has a more laid back sound, and had a better synergy compared to MT-602 (way too powerful and has volume channel imbalances at low volumes with low impedance headphones like Grado). For some reason the MT-601 was picking up some background noise. I moved it to another part of my condo where this noise has reduced, and I sometimes use it for listening.
> 
> If it wasnt for the noise problem, I would use it much more. I contacted the seller and they said it might be the power supply. I ended up changing the tube to Phillips NOS and this did not fix the problem. I thought it was the power so I also invested in a conditioner, that did not fix it either. The 601 also gets quite hot.
> 
> ...


Thanks for the detailed answer. And what could you say about the sound of MT-601? Everywhere reviews only about MT-602 and extremely few reviews about 601 model.

I am interested in can I hear "*soft warm tube sound*" in the MT-601? Many write that 602 model in this sense differs little from the amplifier on the transistors and the tube is not very noticeable in sound.


----------



## SoundGuru

Yea I would say its less forward sounding. These are hybrid amps, so they will not be the full tube experience. It also depends on the tubes used. With the phllips NOS it was definitely on the warm side with smooth treble.


----------



## marbert

SoundGuru said:


> Yea I would say its less forward sounding. These are hybrid amps, so they will not be the full tube experience. It also depends on the tubes used. With the phllips NOS it was definitely on the warm side with smooth treble.


Ok, thank you.


----------



## cirodts

I have the opportunity to buy these valves on amazon for my TA-20 ABOUT 80 EURO PER PAIR
https://www.amazon.it/dp/B01HQYWB7M...olid=1EIC48SPBXWFV&psc=1&ref_=lv_ov_lig_dp_it
you think it's a good deal compared to the standard tubes I have on my TA-20.
Thank you


----------



## marbert

SoundGuru said:


> Yea I would say its less forward sounding. These are hybrid amps, so they will not be the full tube experience. It also depends on the tubes used. With the phllips NOS it was definitely on the warm side with smooth treble.


Oh, sorry, one more question. Does your MT-601 have a strong click when you turn on? And what is the constant voltage at the headphones jack output? If you have measured. And is there any protection in MT-601?


----------



## SoundGuru

Yea but this doesn't always happen. I am not sure of the voltage havent measured.

Not sure what you mean by protection? The amp gets very loud and there is no limiter. I wish the amp gain wasn't so high, so that there was more of a range for suitable volumes.


----------



## CJG888

They are Mullard reissues, standard current production Russian tubes. 80€ per pair is too much.


----------



## cirodts

CJG888 said:


> They are Mullard reissues, standard current production Russian tubes. 80€ per pair is too much.


thanks.


----------



## hmscott

cirodts said:


> I have the opportunity to buy these valves on amazon for my TA-20 ABOUT 80 EURO PER PAIR
> https://www.amazon.it/dp/B01HQYWB7M...olid=1EIC48SPBXWFV&psc=1&ref_=lv_ov_lig_dp_it
> you think it's a good deal compared to the standard tubes I have on my TA-20.
> Thank you


Yes, the Mullard reissue 12AU7 are fine, many enjoy them, here are some good places to get them that have a fair price, and I've bought from them with 100% satisfaction before:
https://www.thetubestore.com/mullard-12au7-reissue
12AU7 Selection: https://www.thetubestore.com/preamp-tubes/12au7-ecc82-tube-types
https://www.vivatubes.com/new-mullard-12au7-ecc82-reissue-vacuum-tube/
12AU7 Selection: https://www.vivatubes.com/new-mullard-12au7-ecc82-reissue-vacuum-tube/
https://tubedepot.com/products/mullard-12au7-ecc82-new-production-preamp-vacuum-tube
12AU7 Selection: https://tubedepot.com/t/tubes/preamp-tubes/12au7-ecc82-cv4003-5814a

Some of these sellers also have ratings or descriptions for their tubes to help decide what to purchase.  Either in the tube listing itself, or in tabs above, look around and discover what they have to offer.

And, you can see their prices vary for specific tubes, so I shop the the lowest price from vendors I trust - that is why it is a good idea to have multiple suppliers, they all get different "deals" on parts themselves and sometimes even the best dealer doesn't get a "best price" on their stock and have to charge a bit more.

That is why I shop around, but I don't always keep strictly to that "best price" criteria, as some dealers are closer and can ship quicker, or offer other services like balancing gain within the tube and externally, and those dealers can cost more.

If they don't off balancing gain options, ask them via their support email if they will balance pairs/quads of tubes, and if they can pick your's for balanced gain within the tube - some amps use only 1 tube so you can't gain average between 2/4 tubes.

Good listening


----------



## cirodts

hmscott said:


> Yes, the Mullard reissue 12AU7 are fine, many enjoy them, here are some good places to get them that have a fair price, and I've bought from them with 100% satisfaction before:
> https://www.thetubestore.com/mullard-12au7-reissue
> 12AU7 Selection: https://www.thetubestore.com/preamp-tubes/12au7-ecc82-tube-types
> https://www.vivatubes.com/new-mullard-12au7-ecc82-reissue-vacuum-tube/
> ...


What is the difference between the Mullard 12AU7 reissues and the originals?
still is the price high for the Mullard 12AU7 reissues?


----------



## CADCAM

MT-602 being fed from a SMSL SU-8 (thank God for the volume control) in turn being fed from a NAD C542, 1967 Sylania's and a pair of Takstar Pro82 should not sound this good...
Listening to some Black Light Syndrome


----------



## cirodts

for the xduoo TA-20 these valves at 50 euros the pair: https://www.amazon.it/dp/B09GB9KD4J...lid=1EIC48SPBXWFV&psc=1&ref_=lv_ov_lig_dp_its are a good improvement in your opinion?


----------



## HTSkywalker

cirodts said:


> for the xduoo TA-20 these valves at 50 euros the pair: https://www.amazon.it/dp/B09GB9KD4J...lid=1EIC48SPBXWFV&psc=1&ref_=lv_ov_lig_dp_its are a good improvement in your opinion?


Good valves, not a good price. Avoid Amazon


----------



## cirodts

from italy where to buy them?


----------



## YanaMJ

cirodts said:


> for the xduoo TA-20 these valves at 50 euros the pair: https://www.amazon.it/dp/B09GB9KD4J...lid=1EIC48SPBXWFV&psc=1&ref_=lv_ov_lig_dp_its are a good improvement in your opinion?


I have the JJ in gold version and sound is far better than the stocks one. Lots of punch. I love them


----------



## cirodts

YanaMJ said:


> I have the JJ in gold version and sound is far better than the stocks one. Lots of punch. I love them


link?


----------



## YanaMJ

cirodts said:


> link?


I've bought them in France I don't know if this would help you


----------



## HTSkywalker

cirodts said:


> from italy where to buy them?


Probably cheaper to ship from the US


----------



## cirodts

it is my first serious tube amplifier after the loxjie p20, I am not an expert on tubes and I do not know from Italy which site to buy, I will try ebay


----------



## cirodts

YanaMJ said:


> I've bought them in France I don't know if this would help you


this https://www.ebay.com/itm/3839545262...3EHGclISO%2BAATF|clp:2334524|tkp:BFBMmPuE5aNf


----------



## YanaMJ (Nov 14, 2021)

cirodts said:


> it is my first serious tube amplifier after the loxjie p20, I am not an expert on tubes and I do not know from Italy which site to buy, I will try ebay


Be careful with ebay...
But if you're from Italy you can buy easily from France. If you want I'll tell you where I've bought mine.


----------



## YanaMJ

cirodts said:


> this https://www.ebay.com/itm/383954526294?_trkparms=ispr=1&hash=item5965792056:g:sO4AAOSwAQ5gKINU&amdata=enc:AQAGAAACkPYe5NmHp%2B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsSQuF9OYLb3wphIAOfpJK8RvXdCi7B%2FY2Ui1shBmqfb2DIe8qc2PQLZBqObNd6VxSgfVZLgjtxy4R0AlOPAbrdOEy4ztWgUC95K%2BIoMqy%2BRpSF%2FVBRI55tXCUPFxsZCyeQs2zRL6g37cPCcY0HJejzNa7bGbzZcPIj9MheXYFhFNHYT4fxuw2H5vK6Fy53zrucmKguBQ3DJJ8T3to%2FiDPbGXp19LzXlCs5OIEMmBhDBba7WYARMDAXE6vWMmIENGjpLIrWQs8FRH3rFgILbNKLuSOmmZ70R1wZnVy4kVY1fUCfX2KgzbwN2Rf%2FgLlq6bCAKII7byQw4gSGaoHu0596O7Mulo2pYjJlSQwiOSCgJDdrelu1cJ7fBcADlAc9r1JDeORoTEBfZRMOG24GvulyvAhaBgLMNCFabj2dbpgvwkRCAioVxbJNuHl02t1%2BK2FJrmzuF14R9C8CzrYW%2BxejMOTGrm94wCqog8k7sidANfm%2FPQuDd08IvV5M5pVB8S2TFQs7LfFgoZVAwjPFYf1Vy4gNhKcXB4gQa3YI8OogvJtaRFi22QKNa%2B6ErUDVd8CG6MN9q%2Fru7axPzMQ6iSg0I2idccmNr1Iwuw%2BJAXlD2JD3ecgThuY7EAKwL%2FmrfXk0a6JdhzT3loNSMBUkyfY7xhBdMbfId3Yx6u4jy00QKoCvekGyj7re33vBu%2FVp%2BjLjz4AFNzWcucJz%2B3Ednb6cd8RucEst%2FwE8GCrJIPsNz3cbH6asxVdrKcEsA2iKPC1eg30jpNojlcD%2FJz9bUVwa0m1KEGzBogAL%2F42H1Zm4yvAWRDytZs3EHGclISO%2BAATF|clp:2334524|tkp:BFBMmPuE5aNf


https://www.atelierdesamplis.com/preamp/12au7-et-ecc82/

You have you to choose JJ gold matched pair, 59 euros for the pair


----------



## cirodts

YanaMJ said:


> Be careful with ebay...
> But if you're from Italy you can buy easily from France. If you want I'll tell where I've bought mine.


Thank you very much


----------



## CJG888

cirodts said:


> for the xduoo TA-20 these valves at 50 euros the pair: https://www.amazon.it/dp/B09GB9KD4J...lid=1EIC48SPBXWFV&psc=1&ref_=lv_ov_lig_dp_its are a good improvement in your opinion?


Look for RFT.


----------



## cirodts

is it a good valve?
https://www.amazon.it/gp/product/B00FWK9U5E/ref=ox_sc_act_title_1?smid=ASLRU2KUH1JUL&psc=1


----------



## hmscott (Nov 16, 2021)

cirodts said:


> What is the difference between the Mullard 12AU7 reissues and the originals?
> still is the price high for the Mullard 12AU7 reissues?


Reissue differences vary, due to previous manufacturing equipment availability for duplication, assembly / manufacturing techniques available for reference, jigs and automation available to repopulate the line, and materials / coatings available - and investment used to recreate the product(s).  It may take them years to get the right mix of materials and techniques - and training of new workers - to get the best product.

To me the reissues are capable and certainly listenable, but not the best in the reproducing the characteristics I am hearing in old NOS tubes I enjoy most.

That doesn't mean you or anyone else wouldn't enjoy them, and they might be prefereable to you to your current stock tubes.   I tried many of them myself, and still have them as reference for comparison, or for trades later.

Reissues are inexpensive enough to be good first tubes for comparisons, maybe temporary end game while you look for your future "end game" tubes 


cirodts said:


> is it a good valve?
> https://www.amazon.it/gp/product/B00FWK9U5E/ref=ox_sc_act_title_1?smid=ASLRU2KUH1JUL&psc=1


FYI -  I have tried the JJ Red/Gold label + steel/gold plated versions of JJ 12AU7 tubes, and while they are fine tubes that work and were more enjoyable than the stock Red label TA-20 stock tubes, I don't pull them out any more to listen to them.  I worked through the JJ tubes fairly quickly, and I moved on to the PSVANE, Telefunken reissues, and Mullard Reissues, and haven't rotated in the JJ tubes since my first days of owning the TA-20.

As a recommendation I'd jump right into the PSVANE, Telefunken reissue, or Mullard reissue, and skip the JJ Electronics, Electro-Harmonix, and similar very inexpensive tubes.  And I can also highly recommend adding 12AT7 versions "along with/instead of" the 12AU7's, at least one of the PSVANE/Telefunken(?)/Mullard 12AT7's to go with your 12AU7's, for comparison, you might like the 12AT7 sound as I do.
After reading of others experience recommending I skip JJ/ElectroHarmonix tubes, I decided I wanted to hear them for myself so I bought several JJ tubes too.


----------



## YanaMJ

At that time, I've tested the JJ gold and the NOS Sylvania green label.

They sound very different and even if I have a little preference, I love both type.

JJ gold have lots of punch (this is what I love with those tubes) with a good soundstage but not huge, highs are a little bright to me.

NOS Sylvania green label have never bright highs, are very balanced and have tight bass. I love their highs and their very balanced feeling when I listen with them. But they have less punch, music is less "alive" (I don't know if it makes sense for you)  than with the JJ gold. It's an easy listening, not fatiguing at all.

The problem with tubes is that you have to test them, we're not all looking for the same things. For example, my husband prefer the JJ gold and I prefer the sylvania.
It also depends of your budget. I don't want to put a lot of money on the tubes and NOS tubes can be very very very expensive.


----------



## cirodts

hmscott said:


> Reissue differences vary, due to previous manufacturing equipment availability for duplication, assembly / manufacturing techniques available for reference, jigs and automation available to repopulate the line, and materials / coatings available - and investment used to recreate the product(s).  It may take them years to get the right mix of materials and techniques - and training of new workers - to get the best product.
> 
> To me the reissues are capable and certainly listenable, but not the best in the reproducing the characteristics I am hearing in old NOS tubes I enjoy most.
> 
> ...


many thanks for your explanations, I would like a tube with a warm, detailed and airy sound to listen to heavy metal music without accumulating listening fatigue, on which tubes would you direct me?


----------



## CJG888

Did I mention RFT?

As I presume you are based in the EU, this might be an idea:

https://www.tubeampdoctor.com/ecc82-rft/e.germany-nos?c=37

I’ve used TAD before, so far they have been a reliable source. Langrex and Watford Valves are now, alas, outside the EU. Bloody Brexit!


----------



## cirodts

CJG888 said:


> Did I mention RFT?
> 
> As I presume you are based in the EU, this might be an idea:
> 
> ...


now I understand what RFT means


----------



## CJG888

VEB Rundfunktechnik


----------



## YanaMJ

Yes TAD is also a reliable source


----------



## hmscott (Nov 16, 2021)

YanaMJ said:


> At that time, I've tested the JJ gold and the NOS Sylvania green label.
> 
> They sound very different and even if I have a little preference, I love both type.
> 
> ...


I've also tried and enjoyed these NOS Sylvania Green label 5963 12AU7/ECC82 compatible, $32.80 shipping found on eBay:





The Sylvania 6201 12AT7/ECC81 equivalents are also very nice:




And, I've found these while looking for images - the sold ebay listings have expired - and found these still available 3 (triple) Mica 6201's still available, a bit more expensive but should be quieter and longer lasting builds of the same design.  In general heavy post triple mica versions are more sought after for their lower noise build components:




Sylvania JHS 12AT7WA / 6201 Triple Mica​*http://www.nostubestore.com/search?q=6201+mica* <= a few other 6201 TMGP (triple mica black plate) in general Black Plate finish, and Silver/Chrome Plate finish are more sought after than grey plates.  Welded plates are another higher priced category => https://fuzzaudio.com/vacuum-tubes-plate-cheat-sheet-fuzz-audio

I haven't bought from this dealer before, but I've run across them many times during searches, hopefully these are a long active listings as there are comments from many years ago.  They have a tab explaining how to order - that is why there are no Buy/Cart buttons to select for ordering.

Then there are these Sylvania variants that look interesting: http://www.nostubestore.com/search?q=sylvania+12au7

These I found early in my search, worn off logos, non-original boxes, but 3 mica grey plate with close to 100% Lifetime measurements were a good early NOS choice.
SYLVANIA GOLD LOGO 3 MICA Gray Plate D Getter JHS 12AT7WA Tubes




BTW, desireme1979 is a great dealer on ebay, very nice to interact with - I encourage you to ask questions, she helped me a lot early on getting back into finding tubes.

Lots of great tubes are out there to find, the hunt is much more rewarding when you find great tubes, 12AU7, 12AT7, she adds to her listings from her inventory frequently.


----------



## cirodts

Out of curiosity between the 2 valves for my Xduoo TA-20:
Mullard 12AU7 and jj electronic ecc82 which one has a more mellow and non-fatiguing sound?


----------



## YanaMJ

cirodts said:


> Out of curiosity between the 2 valves for my Xduoo TA-20:
> Mullard 12AU7 and jj electronic ecc82 which one has a more mellow and non-fatiguing sound?


I don't know the Mullard so I can't answer for them but the JJ gold are more fatiguing than my Sylvania for example. I'd be happy to know for the Mullard too.


----------



## hmscott (Nov 16, 2021)

cirodts said:


> Out of curiosity between the 2 valves for my Xduoo TA-20:
> Mullard 12AU7 and jj electronic ecc82 which one has a more mellow and non-fatiguing sound?


None of the tubes in the TA-20 were particularly "fatiguing" or shrill as some describe some of the tubes I've tried, the emphasis can be on the bright/harsh side like the JJ Electronics - a thin sound overall, or mid/bass heavy in comparison with the JJ Electronic like the Mullard.

I kind of find heavy Bass fatiguing - tiring or wearing on me - just from the pressure changes against my eardrum from beating repetitive Bass, but I don't EQ headphones so I don't force more Bass than is natural from the driver, but it is a matter of personal taste.

The TA-20 Tube/SS amplification is sweet sounding, not dry like the A90 - the original tubes/JJ are more toward that thin sound I don't enjoy much.  Some might hear it as etched or even fragile, not a good solid meaty sound.

Again, it takes some time and gained experience to compliment your components / headphones and match them together into something you find specially leaning to the sound you enjoy.  For me that is the TA-20 + 12AT7/E80CC + Hifiman Ananda/HE6 SE V2 + Sennheiser HD660S.  The D90 MQA is the solid source needed, there are many other candidates for all the positions in the setup.  The FiiO M15 puts DAC/AMP together into one "small" box that is portable, no tubes, yet the sound is better than the A90, but not quite up to the TA-20 with my favorite tubes.

In general the 12AU7's to me sound thinner, and the 12AT7's sound more full and spacious, with harder hitting Bass and more extended high's, with more air and dynamics.

Perhaps if I spent more $$$ on the sought after 12AU7's I might change my views - if the affordable 12AU7's did for me what the much more affordable 12AT7's do  for me I'd recommend them, but for now I haven't found any affordable 12AU7's to recommend over my favorite 12AT7's, even the cheaper 12AT7's sound great.  And, again, I'm talking about $100/pair 12AT7 tubes to $200/pair tubes 12AU7 tubes.

These are the 12AU7's I am eyeing next, but Mullard 12AT7 NOS tube's have been winning out over the 12AU7's for a few months of purchases 

*Matched Pair Mazda NOS/NIB ECC82/12AU7 tubes - France - Test NOS* -$199/pair

These Mullard '58 / '68 12AT7's are half the price and are my 3rd best sounding tubes, behind the Brimar 6060, and top Haltron E80CC's

*Matched Pair Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes* - $99/pair

I think my Haltron E80CC's look like the very clean build of the Philips Harleen made E80CC's, but some other Haltron E80CC's look like Tungsram, and get good reviews.

There are out of Russia and Ukraine brand new never opened till tested Tungsram E80CC tubes for $30-$50 each, and they will match a pair for you upon request.  Some have more expensive shipping and handling charges, and they will take a long time in transit + I've heard of packages going missing as well in/out of Russia during the Pandemic, so I've steered away myself.  But the costs are low and you might get a nice pair of E80CC's for under $100 to try 

https://www.ebay.com/sch/i.html?_nkw=Tungsram+E80CC&_sacat=0&rt=nc&LH_ItemCondition=1000

These are a good example of what my Haltron E80CC's look like.  Mine have either E80CC, E80CC/6085, or 6085 only lettering/labels.  Be careful cleaning them, as my Microfibre cloth apparently had solvent remnants soaked into it and it wiped the lettering clean off of one of my E80CC labeled tubes, that lettering is always mottled as paint drops off over the years.  The labels are very fragile. 

*Matched Pair E80CC HALTRON/ Philip HEERLEN Gold Pin*

Those gold pins look very dirty, so they looked stored out of the original box.  Mine look gold, with some oxidation that wipes off.  Those still are the first I've seen listed on eBay for quite a while.

Here is the equivalent with Philips markings / box for a bit more:

*Matched pair Philips E80CC gold pins Heerlen NOS with original boxes free ship!*

And, the prices go up from there:
https://www.ebay.com/sch/i.html?_nk...&LH_TitleDesc=0&LH_ItemCondition=1000&_sop=15


----------



## cirodts (Nov 16, 2021)

hmscott said:


> None of the tubes in the TA-20 were particularly "fatiguing" or shrill as some describe some of the tubes I've tried, the emphasis can be on the bright side like the JJ Electronics - a thin sound overall, or mid/bass heavy in comparison with the JJ Electronic like the Mullard.
> 
> I kind of find heavy Bass fatiguing - tiring or wearing on me - just from the pressure changes against my eardrum from beating repetitive Bass, but I don't EQ headphones so I don't force more Bass than is natural from the driver, but it is a matter of personal taste.
> 
> ...


thanks, so do you recommend the 12At7 with a fuller and more meaty sound, are they compatible right for the ta-20?
At the same price, the mullard 12AT7 is better than the 12AU7 vreo or am I wrong?


----------



## hmscott (Nov 16, 2021)

cirodts said:


> thanks, so do you recommend the 12At7 with a fuller and more meaty sound, are they compatible right for the ta-20?
> At the same price, the mullard 12AT7 is better than the 12AU7 vreo or am I wrong?


Yes, of course I'd already read about others using the 12AT7/12AX7/E80cc on the TA-20 and TA-30, but I double checked with Xduoo before trying them myself for the first time, I asked Xduoo if the 12AT7/12AX7 were compatible in the TA-20, here is what Xduoo through Hifigo said about tube compatibility on 2 occasions:

"...is it possible to substitute the 12AU7 with 12AT7 or 12AX7 : Xdoo reply yes no problem."

"...E80CC ( 6085 ) is ok to match with TA20 and TA30 xduoo replied,  and they thank you for your questions and testing. "

I haven't done that specific comparison, reissue Mullard 12AU7 pair vs reissue Mullard 12AT7 pair, that would be a great contribution if you bought both and compared them here in the thread.

BTW, I haven't mentioned before that A/B comparison as such isn't really possible for tubes in the same device as it takes time to remove/insert and then wait to warm up the tubes to the same stable operating temperature - about 20-30 minutes, by then the typical immediacy of A/B comparisons is lost... so you need longer listening notes - say a playlist that covers your favorite songs vs audio spectrum and attack notes, and you'll want to write down your observations in a notebook - on a piece of paper - or txt/doc file on your computer/tablet for each tube after it has warmed up to then compare - A/B - your own notes for each pair of tubes.

I'd love to set up 2 TA-20's to then warm up two sets of different tubes to switch between and compare, an actual real-time A/B comparison, maybe someday 

If you are only going to be able to choose one pair of tubes go ahead and get  either one, roll the dice, toss the bones, Eenie Meenie Miney Moe, rock paper scissors, as you'll eventually want 2 different pairs to compare.  I'd say get the Mullard 12AU7 to compare against the (Shuguang) 12AU7 that comes with the TA-20, but then you wouldn't get to hear the 12AT7 right away...but there's no rush...

Please don't kill yourself trying to hear the differences, you can leisurely enjoy the music for 20+ hours - on each pair of tubes - before thinking about making comparisons, it will just come to ou at some point, hey I didn't hear *that* on the XXX tubes, but I do on these.  Sometimes it's obvious, sometimes it is more subtle, you'll see... hear it for yourself, eventually.

You may hear the differences right away, or you might not, it is an ability gained over many hours, weeks, months, years, and it gets more discerning as time moves on - as long as you keep listening all that time.   And, the differences will be more/less apparent in over-the-ear headphones vs IEMs, and Dynamic vs Planar Headphones and Planar IEMs.

What tubes have you tried in your TA-20 so far?


----------



## chillysalsa

The Mullard I tried was quite smooth and lush, at least compared to a JAN and RCA tube. I didn't have any JJ tubes, only used those as 12AX7 tubes in a guitar amp, as they have a bit more drive and harmonics.


----------



## hmscott

chillysalsa said:


> The Mullard I tried was quite smooth and lush, at least compared to a JAN and RCA tube. I didn't have any JJ tubes, only used those as 12AX7 tubes in a guitar amp, as they have a bit more drive and harmonics.


What are your favorite tubes so far when listening on the TA-20?


----------



## chillysalsa

My favorite have been Japanese 5963 Toshiba tubes, these are an industrial 12AU7 designed for low noise allocations, but they are pricey to find now.


----------



## cirodts

I have only tried the standard tubes from the TA-20 but they say they are bad, I would prefer a more meaty sound.


----------



## S Crowther

hmscott said:


> What are your favorite tubes so far when listening on the TA-20?


Amperex Bugle Boy.


----------



## YanaMJ

S Crowther said:


> Amperex Bugle Boy.


Lots of people say the Amperex Holland are the best for TA-20 but hard to find in Europe 😔


----------



## YanaMJ

cirodts said:


> I have only tried the standard tubes from the TA-20 but they say they are bad, I would prefer a more meaty sound.


What is a "meaty sound" ?


----------



## hmscott (Nov 18, 2021)

cirodts said:


> I have only tried the standard tubes from the TA-20 but they say they are bad, I would prefer a more meaty sound.


They aren't so bad, they are just not very "tubey" sounding - they reminded me of the Topping A90 sound, a bit thin and dry.

They are certainly listenable, and running them will "break-in" the TA-20 - you want to test it fully during the return period to bring out any "bugs" in the unit so you won't run into problems needed to fix under warranty.  Unlikely as that is in either case. 

The Shuguang factory was shutdown due to encroaching suburbs and planned to move, but it still hasn't reopened that I am aware of, and the stock of their higher end tubes have been dwindling - at least I see far fewer shops listing them for sale on AliExpress.  Here's a few that might be worth checking out before they disappear altogether...

PAPRI Shuguang 12AU7-T Vacuum Tube Replace Tube For Amplifier Audio HIFI DIY Factory Tested Matched - select Color: 1 Pair, the boxed Matched Set

Shuguang tube 12AU7-T instead of 12AU7 ECC82 vacuum tube quality product precision (pairing) - select Color: 2pcs

And if you ever need a replacement stock tube for the 12AU7, these look like the same to me:

SHUGUANG Tube 12AU7 12AX7 12AT7 made in China - 12AU7, 12AT7, and 12AX7 versions for sale, maybe the 12AT7/12AX7 will sound better? 

The PSVANE Cossor series are "different" in that they have tube length inner Black coating which gives them a unique look:

PSVANE COSSOR 12AX7 12AU7 12AT7 ECC83 ECC82 Vacuum Tube HiFi Audio DIY Vintage Tube Pre-amp Guitar AMP - Select Color: COSSOR 12AT7-1Pair

I haven't heard those, but I do enjoy the similarly inner coated Tung-Sol 12AU7 Black Glass tubes, but those are also very rare - but they do turn up on eBay from time to time, here are some links that describe them:
https://tubemaze.info/tung-sol-12au7-black-glass/
http://www.nostubestore.com/2013/08/tung-sol-12au7-usa.html

There are a few other Shuguang Matched Pair boxed set tubes I recall, but I am not seeing them on AliExpress right now, I'll add them later if I find them.


YanaMJ said:


> What is a "meaty sound" ?


Everyone eventually has their own definition of "Full" or "Meaty" sound vs. "Thin" or "shrill" sound from a tube/amplifier.

For me the tubes with "impact", thick mid-range, full treble extension without tizzy/sparkle distortion, and a wide sound stage that almost or does wrap-around your head.  A Full Sound or Dynamic Sound - as opposed to Thin sound.

In comparison, it is more clearly obvious than described - until you've heard it then you will recognize the description - and add your own words of description.

I bought my FiiO M15 first, and even though it has less specification for wattage than my Topping A90, to my ears the M15 is a more "Full" sound and the A90 is more thin, but not shrill - it is without distortion that I can hear.

Without having heard the M15 first for a few months I might not have realized - or compared - the A90 sound to anything else for a while, and not been motivated to look for that tube sound I remembered as a kid - SS sounded like "junk" back then, more a curiosity than pleasurable listening - in comparison to the long optimized tube sound.

Today there are SS amps that sound like that to me, "junk" or "yuck", the A90 is not that, it sounds great, but it isn't as enjoyable to me as the FiiO M15, or the Xdu00 TA-20 with my favorite tubes.

The FiiO M15 shows me it is possible to make a great full sounding SS AMP without tubes, but even so it isn't all the way there yet either.

Anyway, it's a process, I've been listening to Stereo since the late 1960's, before the Moon landing, and even though I was happy with my Solid State amps "Class A" and Class "AB" for most of that time, I was more interested in the source material and entertainment than optimizing the sound beyond "impact".

Now that I am listening for enjoyment to things I have heard many times, finding the right equipment - headphone AMP, DAC, headphones, IEM's is a nice pastime and to make it more interesting re-listening to old favorites - and discovering new sounds and music as well as discovering older music I missed, I find optimizing the sound helps differentiate it for me and make it more interesting.

I haven't heard my favorite music sound this good ever before 


YanaMJ said:


> Lots of people say the Amperex Holland are the best for TA-20 but hard to find in Europe 😔


I've had to go to Netherlands based dealers on eBay or outside of eBay, for the most part, some German dealers also have reasonable prices on new stock of Heerlen Factory Philips Tubes.  I'm looking to try Philips Heerlen E180cc tubes some time soon...and that reminds me - the Philips Miniwatt 12AU7's and 12AT7's are also worth trying - as are most/all tubes made by Philips Factory in Heerlen, Holland.


----------



## cirodts

YanaMJ said:


> What is a "meaty sound" ?


Sorry, I meant full-bodied sound not thin


----------



## YanaMJ

cirodts said:


> Sorry, I meant full-bodied sound not thin


Ok thanks 😉


----------



## cirodts

I think this world of valves is fantastic and gives infinite choices, having the stock valves to start with what do you recommend between Mullard 12AU7 Preamp Vacuum Tube or jj electronic 12AU7


----------



## schrackin (Nov 18, 2021)

Hi Folks,
has anybody heard the Xduoo TA-10R with the Hifiman Sundara? Would it be a good match?
Currently I'm using a JDS Atom stack as dac amp for my Sundara 2020, I mostly like it, but I'm looking for a little bit warmer sound signature. It would be nice to get a little bit more slam when i listening tracks with drums like instruments_. _


----------



## chillysalsa

For 'meaty' full bodied sound, I would try new production Sovteks, Tungsol, or even the Gold Lions. I am lately prefering reasonably priced new production, after getting a little jaded in regards to NOS tubes that were lauded online, and then finding that NOS RCA, Sylvania JAN tubes to be underwhelming.


----------



## hmscott (Nov 20, 2021)

chillysalsa said:


> For 'meaty' full bodied sound, I would try new production Sovteks, Tungsol, or even the Gold Lions. I am lately prefering reasonably priced new production, after getting a little jaded in regards to NOS tubes that were lauded online, and then finding that NOS RCA, Sylvania JAN tubes to be underwhelming.


Yup, I too went through a downturn when I was disappointed with the RCA Clear Top, RCA Long Black Plate, and some JAN offerings I found all "ho-hum" in a continuous stretch of them, but still they were doing a better job than some, just not top level "wow" material, that is why I don't recommend them in general.

There are specific Sylvania tubes I like, again not top sound, but elevated above most, like the 6201 tubes, even GE 6201's , where I don't usually recommend GE tubes at all, there are some specific models that do stand out.

I actually thought the same as I realized there are too many tubes out there and they all cost $$, I can only audition so many before I am gonna give up, and then I got the Tung-Sol 12AU7 Black Glass pair with 100% Life left, and then found another 2 pair in the same condition, and for a while that was my "find" and joy. 

Whatever keeps you going, researching for tubes you might like, and hunting them down, finally finding a worthy pair, it's a fun and not too expensive way to while away the pandemic, at least for me...

Again, I want to emphasize that NOS is not considered "New/Unused" as the name New Old Stock implies.  I've gotten to know a number of dealers and a few have told me that NOS is considered "measures NOS", but is a range that includes clearly "Used tubes".  And, I also found that tubes starting at 95% life left as measured with a calibrated tube tester, is the point tubes start HISSing while listening with IEMs.

So I now specifically only buy "New" tubes that actually measure at the top of the specific tube measurement chart.  There are enough great tubes out there still that you don't have to settle for "used" tubes.

I'd recommend to hang in there, enjoy the new reissues - they are also good tubes - but if you find a pair with potential, get it and give it a try, you might find a gem in amongst the dross.  

*Update: *here is a long time NOS dealer - Brent Jesse, he has a lot of great listings with descriptions to pick up on details for tubes when hunting - I use his listings as a reference from time to time, and he has a lot of detailed entries for tubes not currently in stock I find interesting, but most of the ones I want from his inventory that are in stock are far too expensive for me to spend, so I just look and find inexpensive tubes elsewhere... his inventory does turn over quickly, so checking daily is a good idea if you are looking for specific tubes - try emailing him with questions too, he is a great guy and I enjoyed purchasing from him. 
http://www.audiotubes.com/12au7.htm
http://www.audiotubes.com/12at7.htm


----------



## AudioCats

does anybody have a picture of the TA-26's power transformer? 

I am wondering what type they are using and how big.


----------



## hmscott

AudioCats said:


> does anybody have a picture of the TA-26's power transformer?
> 
> I am wondering what type they are using and how big.


Not sure, but I don't think I've seen anything but the bottom of the Xduoo Hybrid Headphone amp transformers - wires coming out into the chassis - and I think those are likely sealed/potted during assembly.  I've knocked on the top of my transformer box on top of the TA-20 and it doesn't ring it thumps solidly - like it's filled with potting material.

Has anyone taken their Xduoo Hybrid apart to see from the bottom where the wires from the transformer come in if they are coming out of a solid block?

It is common practice to pot transformers to stop vibrations being transferred into the chassis causing audible noise and component vibration issues.


----------



## duanepo

hmscott said:


> but after 1+ years of enjoying the TA-20, tube rolling, and going back and forth between it and my Topping A90, I only listen with the TA-20.


Curious what made you ditch the A90 and listen exclusively with your TA-20. May i know what headphones you use these with mostly?  Looking to get a TA-20 as well soon.


----------



## hmscott (Nov 22, 2021)

duanepo said:


> Curious what made you ditch the A90 and listen exclusively with your TA-20. May i know what headphones you use these with mostly?  Looking to get a TA-20 as well soon.


It actually happened pretty quickly, right after I received the TA-20 I popped out the stock tubes and put in PSVANE 12AU7-T MkII's, and from then on I pretty much only used the TA-20.  I did try to keep using my A90, but now it only gets a little "on time" when I need to change tubes - while I wait for them to cool down, and I want to listen - then when the tubes are swapped I switch back from the A90 to the TA-20.

Also, when I need to "warm up" the TA-20+E80CC tubes during cold weather I'll also let the A90 run for a while, then when the E80CC tubes are running stable with no "Protect" standby - the E80CC tubes are warm enough to run, I'll switch back to the TA-20 and turn off the A90.

So, my A90 is still pretty much an invaluable part of my audio set up.


----------



## duanepo

hmscott said:


> It actually happened pretty quickly, right after I received the TA-20 I popped out the stock tubes and put in PSVANE 12AU7-T MkII's, and from then on I pretty much only used the TA-20.  I did try to keep using my A90, but now it only gets a little "on time" when I need to change tubes and I want to listen - then when the tubes are swapped I switch back from the A90 to the TA-20.
> 
> Also, when I need to "warm up" the TA-20+E80CC tubes during cold weather I'll also let the A90 run for a while, then when the E80CC tubes are running stable with no "Protect" standby - the E80CC tubes are warm enough to run, I'll switch back to the TA-20 and turn off the A90.
> 
> So, my A90 is still pretty much an invaluable part of my audio set up.


I see ! Thanks for sharing!


----------



## marbert

Wiljen said:


> Also posted the MT-601 and 602 tube rolling articles to my blog for those interested


Hello Wiljen, I saw a photo of *MT-601* circuit board in your review on audiofool.reviews, it is very similar to the fissure next with a tube connector (see the attached photo). It arose when you tried to replace the tube?


----------



## Wiljen

marbert said:


> Hello Wiljen, I saw a photo of *MT-601* circuit board in your review on audiofool.reviews, it is very similar to the fissure next with a tube connector (see the attached photo). It arose when you tried to replace the tube?


Honestly, I sent the 601 out to Josh Trienen sp? to have a look at a couple months back now and he's run into some other issues so I have not received it back to look at.   I don't recall any issues with trading tubes on that board but with no central support I can see how repeatedly trading tubes would cause flex in the pcb and might eventually lead to a problem.  If/when it returns, I'll take another couple photos and see if it has worsened.


----------



## hmscott (Nov 23, 2021)

tubemazestore on ebay is having a 15% off Thanksgiving sale - through Dec 1, 2021

I really enjoy the '58 Quad Mullard's I bought:

RARE Matched *Quad *NOS/NIB GEC/Mullard B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958
https://www.ebay.com/itm/174432228156

Also available as a pair:

RARE Matched *Pair *NOS/NIB GEC/Mullard B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958
https://www.ebay.com/itm/174474431717

and tubemazestore recommends the '68's as having a lower noise floor.:

RARE Matched *Quad *Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes
https://www.ebay.com/itm/174841732527

Also available as a pair:

RARE Matched *Pair *Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes
https://www.ebay.com/itm/203136271616

He has several pages of tubes at 15% off...
https://www.ebay.com/sme/tubemazest...ent&_soffid=8324385403&_trksid=p2047675.m2197


----------



## PetFju

Hi guys. I am pretty new to the scene here, and so far i daily a pair of Hifiman Sundaras that are driven by a ADI-2 dac through a Little-Dot 1+. I am quite happy with that setup, but i i have ordered a xDuoo TA-20, which is on the way 
My question to the gurus in here though; I have rolled both tubes and op-amps on my LD 1+, with good results. And i was wondering if there is any reason to change opamps in the TA-20, and if so; what are the alternatives to its pair of Ti OPA926 or the Ti OPA1612?

Best regards
-Pete


----------



## wakokokoyz

picked up xa-10 couple of days ago. this is a great all in one dac-amp. compact, powerful and stylish. it may not measure well or not the most detailed dac-amp but its freaking engaging and fun to listen to. plus, that tube-ish sound😍


----------



## cirodts

I bought used 2 g and 5814 with 5 green stars, the sound of the TA-20 has become cleaner and fuller, very beautiful.


----------



## cirodts

hmscott said:


> It actually happened pretty quickly, right after I received the TA-20 I popped out the stock tubes and put in PSVANE 12AU7-T MkII's, and from then on I pretty much only used the TA-20.  I did try to keep using my A90, but now it only gets a little "on time" when I need to change tubes - while I wait for them to cool down, and I want to listen - then when the tubes are swapped I switch back from the A90 to the TA-20.
> 
> Also, when I need to "warm up" the TA-20+E80CC tubes during cold weather I'll also let the A90 run for a while, then when the E80CC tubes are running stable with no "Protect" standby - the E80CC tubes are warm enough to run, I'll switch back to the TA-20 and turn off the A90.
> 
> So, my A90 is still pretty much an invaluable part of my audio set up.


I also had the a90 then I sold it and I got the TA-20 I'm very satisfied, I installed some G.E. 5814 with five green stars and the TA-20 sounds great.
Get to know the G.E. 5814a?


----------



## hmscott

Heads up, I posted some responses from Xudoo on opamp's used on the TA-20 to the Opamps thread:
https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436


----------



## hmscott (Dec 18, 2021)

cirodts said:


> I also had the a90 then I sold it and I got the TA-20 I'm very satisfied, I installed some G.E. 5814 with five green stars and the TA-20 sounds great.
> Get to know the G.E. 5814a?


I had heard those were a good choice, the GE 5814(a) series, especially the 3 Mica and 5 Star - IDK if Green vs White 5 Star makes a difference in build, it might be Green was added when printing color came into vogue.

The Brimar Yellow T 6060 tubes for instance came out in the 1950's, but weren't printed Yellow, they had a temperature safe plastic applique for the Big Yellow T 

When I started out with the TA-20 I bought a pair of Phillips JAN 5814A:





And they sounded good, but nothing like what I've heard since moving to 12AT7/ECC81/E180CC/E80CC tubes.  I've found I prefer the 12AT7 specification tubes over the 12AU7 and equivalent, like the 5814A.  But, I haven't heard the Green 5 Star GE 5814a's yet 

I've read the GE 5814a Green 5 Star tubes have the best sound of the series, but there are a lot of Military spec tubes also available - 5 White Star, and JG-5814A, all with 3 Mica and Square D Getters.  Have you tried any of those? should I try those when I find them?

I would think the White labeling would be older tubes - usually built to higher Mil spec, than the commercial Green 5 Star's, but sound tells through the specs, have you tried White 5 Star's of the same or better specification to the 5 Green Stars?

Color tube labels came out the 70's/80's well after the Golden age of tubes - so far the 50's/60's tube have been the sweet spot.  The 50's sound as good but the 60's built can have lower noise measurements.

Right now, these two are my favorites, I received the lower noise measuring '68 build tubes yesterday:

RARE Matched Quad Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes (1968)
https://www.ebay.com/itm/174841732527

RARE Matched Pair Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support tubes (1968)
https://www.ebay.com/itm/175054641567

RARE Mullard NOS/NIB M8162/ECC81/12AT7 Dual getter support Copper plates tube (1968)
https://www.ebay.com/itm/174346933341

These are the first set I received in September, and still enjoy:

RARE Matched Quad NOS/NIB GEC/Mullard B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958
https://www.ebay.com/itm/174325851178

RARE Matched Pair NOS/NIB Mullard GEC/B309/M8162/CV4024/12AT7WA/ECC81 tubes 1958
https://www.ebay.com/itm/174910341182

RARE GEC/Mullard NOS/NIB B309/M8162/CV4024/12AT7WA/ECC81 tube - England 1958
https://www.ebay.com/itm/184391947782

If you find any Green 5 Star GE 5814a Quad/Pair, please let us know 

Update: @cirodts It looks like desireme1979 an ebay seller I trust has a bunch of GE 3 Mica 5814a variants in stock with 100%+/100%+ measurements - plus/minus - but no Green 5 Star GE's...should I give any of these a try?
https://www.ebay.com/sch/m.html?_ssn=desireme1979&_osacat=0&_armrs=1&_odkw=&_nkw=GE+3+mica&_sacat=0


----------



## hmscott (Dec 7, 2021)

Moving discussion from here:
https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436


PetFju said:


> Thank you so much for the info. I did try to find info about this in the Xduoo thread as well, but i guess i didn't look well enough
> Anyways, i do use the balanced inputs from my ADI-2 dac. So i guess there's no need to change anything. And i do have a pair of mullards on the way here, as well as some other tubes, can't even remember which ones atm. Sorry for hijacking this thread, i'll continue about this in the xduoo thread
> 
> -Pete


Yeah, not much out there on swapping TA-20 opamps, likely due to the small clearance between the board and the base plate, so I ended up asking Xduoo directly.  It was very nice of Xduoo to respond with such detail (see Xduoo responses here), it really answers all my TA-20/opamp questions 

Which Mullards did you get?  Link?  I have posted some recent ones I've bought that I enjoy in this post:
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16699553


----------



## PetFju (Dec 7, 2021)

hmscott said:


> Moving discussion from here:
> https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436
> 
> Yeah, not much out there on swapping TA-20 opamps, likely due to the small clearance between the board and the base plate, so I ended up asking Xduoo directly.  It was very nice of Xduoo to respond with such detail (see Xduoo responses here), it really answers all my TA-20/opamp questions
> ...


 Got a matched pair (not that it matters tho  ) of Mullard 12AT7WA / CV4024 Do not know more about them really, but they are modern variants i believe
Edit; i checked now, they're actually NOS tubes.


----------



## PetFju

I am also considering getting a pair of Genalex Reissue 12AT7 ECC81 GOLD PINS https://www.ebay.com/itm/1528916184...&brand=Genalex&_trksid=p2506613.c100290.m3507


----------



## hmscott (Dec 20, 2021)

PetFju said:


> I am also considering getting a pair of Genalex Reissue 12AT7 ECC81 GOLD PINS https://www.ebay.com/itm/152891618472?_trkparms=amclksrc=ITM&aid=111001&algo=REC.SEED&ao=1&asc=20160727114228&meid=791b179fe3bd478d884c3403c549eb33&pid=100290&rk=1&rkt=4&sd=152891618472&itm=152891618472&pmt=1&noa=1&pg=2506613&brand=Genalex&_trksid=p2506613.c100290.m3507


I have a pair of the Genalex Reissue 12AU7's and they sound good, and I was wondering how the Genalex Reissue 12AT7's might sound, please report back after you've run them for a while - usually 100-200 hours is enough, and let us know how they compare to other tubes you enjoy 

I do recommend Viva Tubes, I've bought from them before myself, but I usually shop for the lowest price, and right now that is also tubemazestore on ebay:
https://www.ebay.com/sch/i.html?_nk...pins&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15

Matched Pair Genalex ECC81/12AT7/B739 tubes Gold Pins - Russia
https://www.ebay.com/itm/174820418205

Even without the 20% Holiday Discount, their price is lower than Viva Tubes... either one would be fine, maybe Viva Tubes would do price matching if you asked nicely?


----------



## PetFju

hmscott said:


> I have a pair of the 12AU7's and they sound good, was wondering how the 12AT7's might sound, please report back after you've run them for a while - usually 100-200 hours is enough, and let us know how they compare to other tubes you enjoy
> 
> I do recommend Viva Tubes, I've bought from them before myself, but I usually shop for the lowest price, and right now that is also tubemazestore on ebay:
> https://www.ebay.com/sch/i.html?_nk...pins&_sacat=0&LH_TitleDesc=0&LH_BIN=1&_sop=15
> ...


Thank you for the tip about the different shops. I usually try to buy locally, as there is at least a semi-probability of getting any issues that might arise resolved quickly and without too much hassle. 
I will let you know how i find the new tubes, read somewhere else (can't remember where) that the 12AT7's are a good pairing for this amp. But i guess we'll see. But i do have some hopes for better sound, because right now the Little Dot 1+ (although modded quite a bit) actually sound better with a wider soundstage and in general better tonality than the TA-20. And i have no doubts about the fact that the TA-20 is the superior amp, it just needs a little bit of love


----------



## hmscott (Dec 9, 2021)

PetFju said:


> Thank you for the tip about the different shops. I usually try to buy locally, as there is at least a semi-probability of getting any issues that might arise resolved quickly and without too much hassle.
> I will let you know how i find the new tubes, read somewhere else (can't remember where) that the 12AT7's are a good pairing for this amp. But i guess we'll see. But i do have some hopes for better sound, because right now the Little Dot 1+ (although modded quite a bit) actually sound better with a wider soundstage and in general better tonality than the TA-20. And i have no doubts about the fact that the TA-20 is the superior amp, it just needs a little bit of love


Well, tube only amps will give more "tubey" sound, but I've found the 12AT7 Mullard's of the links I've shared, in my TA-20, have given the widest sound stage and most focused sound for directionality - instrument and "enemy" placement, while being not too expensive.

I've ordered these Mullard E180CC tubes, and will report back when I hear them, I'm hoping they are the 12AT7 version of the E80CC tubes:

Matched Pair E180CC NOS Mullard Holland Valve Tubes
https://www.ebay.com/itm/111861807456

They also have unmatched single tubes for less:

E180CC 5965 12AV7 NOS Mullard Holland Valve Tubes
https://www.ebay.com/itm/112112339682

I've also seen Mullard E80CC tubes, maybe next month


----------



## Silver Wolf (Dec 13, 2021)

Have to just look often and keep your eyes peeled for NOS deals.

Just scored a matched pair NOS Mullard m8162 tubes (build: 1968 models, Mullards own factory at Mitcham), even the boxes still look minty... $60 isn't bad, I'm happy.

Been stuck on these old 12au7 Brimars, will be my first set of 12AT7 in the TA-20


----------



## PetFju (Dec 16, 2021)

So my Mullard tubes got stuck in shipping. So still no news on those 12AT7 mullards as of yet. But i did get a pair of NOS 12AU7 WE JAN GE tubes. I have the samy brand/type in my Little Dot 1+, where they excel, and figured i could try the 12AU7 versions as well, just for the hell of it. I know it's not apples to apples comparison, but i figured it was worth a shot. 
So far i have played 4-6 hours on them and they certainly sound cleaner than the stock tubes. However, they are almost TOO clean. I'll have to give them another 10-20 hours before i judge them, but as of now they are just very very "accurate" sounding, and has a medium/normal soundstage with a good amount of separation. 
I am looking forward to having them go head to head with the Mullard tubes 
Btw; so far they have made it so that the TA-20 by far has outdone the Little Dot as far as sound quality goes, so they are certainly doing something right..That is on the Hifiman Sundaras as well as the Sennheiser 58X jubilee's.


----------



## PetFju

On another note; i just got a "collect-notice" on two pairs of matched RCA cleartop 12AU7 from tubedepot. I forgot i ordered those..lol  But i'll have a go with them throughout the week-end as well, and i'll post my findings. Have a good one out there!


----------



## PetFju (Dec 18, 2021)

Ok, so after a few hours on the GE 12AU7WE JAN and the RCA 12AU7 cleartops i am surprised to say the differences aren't glaringly obvious. 
So far i do not get all the hype around the RCA tubes, but it might just be that they need more burn-in. 
I did however recieve my "Royal Air Force" Mullard CV4024/12AT7's. And oh boy...They've only been in the TA-20 for less than 30 minutes, and as such one can say that they're not burned in, or even warmed up for that matter, but the sound..This is why i got a tube amp in the first place. Just airy and big, with taut bass, yet detailed and smooth highs. If this carries on, or gets even better with time, i honestly think these tubes are a golden pick for these amps. 
I will update after some time has passed. Have a good week-end everyone!


----------



## CJG888

Where did you get RAF surplus CV4024s?


----------



## PetFju (Dec 18, 2021)

CJG888 said:


> Where did you get RAF surplus CV4024s?


I sourced them locally here in Norway. Also i didn't know they were RAF surplus until i checked their markings/designation. 
I see now that the ad is down, so i don't know if he has any more of them, but you could contact him at: 

https://www.hifisentralen.no/forumet/members/kimandersen.25342/

Please note that this forum is norwegian, and as such you might have some language issues.. 

-Pete

Edit- Btw, i see these are also sold here: https://upscaleaudio.com/products/mullard-cv4024-12at7


----------



## PetFju (Dec 18, 2021)

"Deleted" - Can be removed by admin


----------



## hmscott (Mar 6, 2022)

r343 said:


> Does TA-20 rca Output tune signal with tubes or is it just passtrough?





Cran said:


> Some users here say RCA doesn't pass through:
> 
> But users there say the reverse:
> https://drop.com/buy/xduoo-ta-20-ba...k/2785712?utm_source=linkshare&referer=EM4X5H
> ...


Xduoo Confirmed through Hifigo that the TA-20 RCA Output is a passthrough - without going through the Tube/SS stages.

Xduoo's TA-20 Manual has this to say:


Which says the TA-20 RCA Aux1/Aux2 ports output directly through the AUX Output port without passing through the Tubes or SS, a simple source passthrough.

The Xduoo TA-26 AUX Output (RCA) does go through the tubes. The *TA-26 PDF Manual* says:


Product details not mentioned in the marketing materials, are often mentioned in the product manuals


----------



## hmscott (Dec 19, 2021)

PetFju said:


> Ok, so after a few hours on the GE 12AU7WE JAN and the RCA 12AU7 cleartops i am surprised to say the differences aren't glaringly obvious.
> So far i do not get all the hype around the RCA tubes, but it might just be that they need more burn-in.


I think the RCA Cleartop 12AX7 in Guitar Amps has the "special edge", at least that is what I've heard.  In the TA-20 the 12AU7 RCA Cleartop sounds nice, but nothing "special".  Same goes for the JAN tubes I've heard - great but nothing special.  Only the Tungsram Black Glass 12AU7 and Tungsram/Philips E80CC (12AU7) stands out for me so far, but the 12AT7's outshine all of the 12AU7s I've heard so far.


PetFju said:


> I did however recieve my "Royal Air Force" Mullard CV4024/12AT7's. And oh boy...They've only been in the TA-20 for less than 30 minutes, and as such one can say that they're not burned in, or even warmed up for that matter, but the sound..This is why i got a tube amp in the first place. Just airy and big, with taut bass, yet detailed and smooth highs. If this carries on, or gets even better with time, i honestly think these tubes are a golden pick for these amps.
> I will update after some time has passed. Have a good week-end everyone!


That is awesome!, I'm happy for you, it's great to find a sweet sounding pair of tubes, it makes all the time hunting worthwhile. 

That's pretty cool about the "Royal Air Force" branding; please post some photo's when you get a chance of the tube lettering on the sides, and if you find some more, please "share" a link. 

The best 12AU7's I've heard don't have the airy sound of the '58/'68 Mullard M8162 CV4024 BVA Made in England - or 12AT7s in general - as compared to 12AU7s in the TA-20.

The E180CC NOS Mullard Holland Valve Tubes and E180CC 5965 12AV7 NOS Mullard Holland Valve Tubes are still in transit, the Royal Mail tracking peg hasn't moved for 10 days and probably won't till it makes land-fall, hopefully soon.  USPS is now showing the tracking too, a good sign.


----------



## hk29

Quick impressions on the MT604 with the stock tubes using iBasso DX220 Max balanced line out to Meze Empyrean:

1) Takes of the sharp edges of sounds and rounds them out
2) Provides holographic image
3) Bass blooms nicely (Less detail, but pleasant)
4) "Darker"/ treble is rolled off slightly with less air -- I suspect this is due to the stock tubes.

Overall really nice and "musical" - vocals sound real.   And I think the level of detail from the MT604 is "good enough" in the sense that its about the same as I would normally hear in real life talking to someone. 

It's a nice complement to the iBasso sound which is more transparent, sharper image, more detailed, and slightly warm.   They both sound forward and intimate.

Lastly, the dual volume control is a pleasure to use and very easy;  You adjust one, and the other when the image snaps in the middle and it sounds balanced;  it takes another 1-2 seconds to adjust it in.  The volume knobs have a nice weight and are smooth.  Of course if you're OCD (no offense intended), then maybe you'd feel a bit more hesitant, but then this $170 amp probably isn't for you to begin with ... point is don't let the dual volume knob sway you away from trying this amp.   

And because I use 4.4mm from the iBasso, its great the MT604 uses 4.4mm as well.   

Great little amp!  This will do nicely when I just want a bit of tube sound but still maintain a transportable system...


----------



## PetFju

hmscott said:


> That is awesome!, I'm happy for you, it's great to find a sweet sounding pair of tubes, it makes all the time hunting worthwhile.
> 
> That's pretty cool about the "Royal Air Force" branding; please post some photo's when you get a chance of the tube lettering on the sides, and if you find some more, please "share" a link.



Here Is a picture of the tube. It also has some faint typings on the back, as you can see i picture 2. The boxes they came in are standard white with black lettering
[


----------



## Silver Wolf

If I'm reading codes correctly looks to be Mullard's own Mitcham factory, build week 3 of Jan 1972, but I get confused easily lol.


----------



## PetFju

Silver Wolf said:


> If I'm reading codes correctly looks to be Mullard's own Mitcham factory, build week 3 of Jan 1972, but I get confused easily lol.


It might be me who's confused here. I Honestly don't know much about this other than what Google tells me..lol


----------



## Silver Wolf (Dec 19, 2021)

My understanding is the bottom line of code on the back tells you factory and production date info.


----------



## cirodts

when I insert the valve on the right side of my TA-20 I hear a click what could it be?


----------



## hmscott (Dec 21, 2021)

cirodts said:


> when I insert the valve on the right side of my TA-20 I hear a click what could it be?


With the power off, you hear a mechanical click?  There could be a loose nut/bolt for that tube "riser" that holds the socket, perhaps?  Mechanical stress can cause even tight couplings to "creak/click".  If the TA-20 wasn't so tightly packed between the bottom plate and that assembly I'd suggest taking a look, but for now I wouldn't go that far, yet.  Perhaps it won't further loosen, but over time it might.  Keep an ear on it for now? 


Silver Wolf said:


> If I'm reading codes correctly looks to be Mullard's own Mitcham factory, build week 3 of Jan 1972, but I get confused easily lol.





PetFju said:


> It might be me who's confused here. I Honestly don't know much about this other than what Google tells me..lol





Silver Wolf said:


> My understanding is the bottom line of code on the back tells you factory and production date info.


Here are some online listings of the codes and how to read them; you both sound like you've found them ok - these are a few of the useful links I've found that might help others too:
https://mullard.org/blogs/news/mullard-valve-etched-codes-how-to-interpret-them
https://www.audiotubes.com/mullcode.htm
Download or view the tube type code list.

That last link is "Brent Jessee's" and he lists and sells tubes too, even if the entry is out of stock much can be learned from his tube listings.  These are his 12AU7 and 12AT7 listings, also the preamble of tube variants leading each for sale listing is very helpful when looking for new tube types:
http://www.audiotubes.com/12at7.htm
http://www.audiotubes.com/12au7.htm


----------



## waveSounds (Dec 20, 2021)

Hey folks, I had an MT-602 turn up today - which I'm enjoying so far with a pair of Mullard CV4010 tubes I already had from a Little Dot MKII - but I have a question about its operation. What's the general consensus on when to plug in and unplug the headphones in regards to powering on and off? I know the amp waits for about ~20 seconds before it literally clicks into operation with a bit of the sound transmitting through the drivers, but if my cans are still plugged in when I turn it off it produces a pop much louder. Is this the norm with these amps?

Edit - searched the thread and found this from a member earlier on.



CADCAM said:


> My 602 also has a nasty pop when you turn the unit off, I unplug my headphones every time I remember. I don't understand why this wasn't addressed by Xduoo during development/production of this amp. Long term affects of the pop and the extra unplugging and plugging of the headphones...



Unless anyone else has something else to add I guess I'll just follow this chaps advice and go with unplugging prior to turning the amp off.


----------



## hmscott (Dec 20, 2021)

waveSounds said:


> Hey folks, I had an MT-602 turn up today - which I'm enjoying so far with a pair of Mullard CV4010 tubes I already had from a Little Dot MKII - but I have a question about its operation. What's the general consensus on when to plug in and unplug the headphones in regards to powering on and off? I know the amp waits for about ~20 seconds before it literally clicks into operation with a bit of the sound transmitting through the drivers, but if my cans are still plugged in when I turn it off it produces a pop much louder. Is this the norm with these amps?
> 
> Edit - searched the thread and found this from a member earlier on.
> 
> ...





CADCAM said:


> My 602 also has a nasty pop when you turn the unit off, I unplug my headphones every time I remember. I don't understand why this wasn't addressed by Xduoo during development/production of this amp. Long term affects of the pop and the extra unplugging and plugging of the headphones...


Xduoo should have designed in a function like at power on to switch out the headphone(s) when switching off the amp, to eliminate Pops when powering down:
https://xduoo.net/product/mt-602/

Perhaps Xduoo did intend that same circuit/relay design to also interrupt the signal to the headphones during power off?

I'll ask Xduoo, and you guys can also use the contact form at Xduoo, or email service@xduoo.com to report the problem. "The squeaky wheel gets the grease" 

I've seen pop reducers for speakers, perhaps there are some that could be used for headphones, I'll update here if I find them...

Here are a few inline filters that also mention removing pops.  Perhaps one of those will attenuate that shutdown pop enough that you can feel comfortable leaving your headphones connected at power off with one inline.

Perhaps @iFi audio knows which would be the best one to try for your Pop at shutdown issue?

"Annoyed by hisses and pops from your earphones?" - iFi Ear Buddy
https://ifi-audio.com/products/ear-buddy/

"Do your earphones suffer from pop and hiss? Sound quality just not quite ‘there’ at normal listening levels?
You need the iEMatch+"
https://ifi-audio.com/products/iematch-plus/

"Do your earphones suffer from irritating hiss and pop? Not getting the full impact of your music?"
iFi iEMatch(3.5), iEMatch4.4, iEMatch2.5,
https://ifi-audio.com/products/iematch/
https://ifi-audio.com/products/iematch4-4/
https://ifi-audio.com/products/iematch2-5/

You could also use a front end switch box - 6.35mm/3.5mm headphone outputs to single 3.5/6.35mm input, and before powering off switch to an empty headphone output position.

The "Nobsound Little Bear 4 Way Audio Switch" has a big Red Mute button that you could press before powering down the MT-602 to block that "Pop".  A nice side benefit is you can connect 4 of your headphones at the same time, and switch between them. 

Nobsound Little Bear 4 Way Audio Switch; 3.5mm Audio Switcher; Stereo AUX Audio Selector; Audio Splitter; 4(1)-in-1(4)-Out
https://www.amazon.com/Nobsound-Audio-Switcher-Selector-Splitter/dp/B07Q1W4484


----------



## waveSounds

Thanks for that, @hmscott. Really helpful stuff! I actually already have an IEMatch but hadn't thought about using it with this amp until you mentioned it. I've just plugged it in (set to ultra) so we'll see what happens when it's time to flip the power switch in a bit. At the very least, it has expanded my usable volume from just below 9 o'clock with a significant decrease in source volume to boot, to 12 o'clock and only a minor decrease in source volume. A small win, eh!


----------



## Silver Wolf (Dec 20, 2021)

Just got the NOS Mullard m8162 factory matched pair I bought last week. Certainly in good/like new condition for age, just fitted them in to the TA-20 and am about to have a listen once they warm up.


----------



## waveSounds

waveSounds said:


> Thanks for that, @hmscott. Really helpful stuff! I actually already have an IEMatch but hadn't thought about using it with this amp until you mentioned it. I've just plugged it in (set to ultra) so we'll see what happens when it's time to flip the power switch in a bit. At the very least, it has expanded my usable volume from just below 9 o'clock with a significant decrease in source volume to boot, to 12 o'clock and only a minor decrease in source volume. A small win, eh!



Update: with the IEMatch set to ultra, the pop on power off can still be heard but is greatly reduced to near negligible levels. Happy to leave the cans attached now. Thanks @hmscott for the suggestion!


----------



## PetFju

Silver Wolf said:


>


Looking good there! I am looking forward to hearing your impressions after a little while with the tubes under load.


----------



## Silver Wolf (Dec 22, 2021)

PetFju said:


> Looking good there! I am looking forward to hearing your impressions after a little while with the tubes under load.



I'm certainly enjoying them already, high on my keeper list.... As an early guesstimate they will prolly knock me off my beloved Brimar's lol with thanks @hmscott for suggesting them. Similar sound signature, I guess both British 1960's competing tubes so understandable. Initial impressions, for the higher gain sound floor is very low/quiet which surprised me but the extra push seems to help with bass/bottom end control. To keep it short, I think imaging is very good indeed and mid-range is delightful and meaty. Very organic and inviting with improved dynamics overall, glad I tried them because they may be a new fav.

I wonder, has anyone tried 12BH7A tubes as yet in the TA-20. Just been advised on a nice buy on a matched NOS pair so may try them as well, though I imagine tube protection rails may not fit with taller tubes. Not an issue for my situation, so wondering about giving them a try...price is right though my wallet is empty/tight lol being the time of year it is.

Some of the tunes/playlists I enjoyed in my listening session/s this afternoon, sorry in advance for my eclectic tastes lol... I have been sampling homemade booze as well


----------



## hmscott (Dec 23, 2021)

Silver Wolf said:


> I'm certainly enjoying them already, high on my keeper list.... As an early guesstimate they will prolly knock me off my beloved Brimar's lol with thanks @hmscott for suggesting them. Similar sound signature, I guess both British 1960's competing tubes so understandable. Initial impressions, for the higher gain sound floor is very low/quiet which surprised me but the extra push seems to help with bass/bottom end control. To keep it short, I think imaging is very good indeed and mid-range is delightful and meaty. Very organic and inviting with improved dynamics overall, glad I tried them because they may be a new fav.


That's great, and I've found the same, I really enjoy the Brimar 6060's, but the Mullard Mitchum 12AT7's are as good or better for air and dynamics 


Silver Wolf said:


> I wonder, has anyone tried 12BH7A tubes as yet in the TA-20. Just been advised on a nice buy on a matched NOS pair so may try them as well, though I imagine tube protection rails may not fit with taller tubes. Not an issue for my situation, so wondering about giving them a try...price is right though my wallet is empty/tight lol being the time of year it is.


Yup, with the E80CC's I turn the protection bars upside down - legs pointed up, and slide them in around the tubes to at least give the illusion of protection - a reminder to not touch the *HOT* tubes 

I've not tried the 12BH7A's yet, I'd compare the pin-outs against some specification sheets - check B+ current requirements, and do some sleuthing to see if anyone else has run them in the TA-20/TA-30... I have a fuzzy recollection seeing someone talking about them for the TA-30, but no link to share right now...


----------



## marbert

waveSounds said:


> Hey folks, I had an MT-602 turn up today - which I'm enjoying so far with a pair of Mullard CV4010 tubes I already had from a Little Dot MKII - but I have a question about its operation. What's the general consensus on when to plug in and unplug the headphones in regards to powering on and off? I know the amp waits for about ~20 seconds before it literally clicks into operation with a bit of the sound transmitting through the drivers, but if my cans are still plugged in when I turn it off it produces a pop much louder. Is this the norm with these amps?


I'm afraid the general problem is that xDuoo engineers don't want to strain with inexpensive models. They could provide a delay when turned on, add the relay, but no... Is it so difficult for xDuoo engineers?

For example, recently, I measured the temperature of my MT-601 (_attached the results below_). Two of the four transistors installed vertically with radiators, while the other two transistors soldered onto the board. In this case, the board becomes a radiator and heats the adjacent elements. As a result - the temperature of the headphone jack 6.3 mm has more than 60 °C (degrees Celsius). Although the jack should not be heated so much.

Keep in mind, this is an open board and when the amplifier is assembled, the temperature will be even higher.

Yesterday I wrote in xDuoo and showed them the results, but they still have not answered.


----------



## cirodts

just for curiosity how do you release the crown where the valves are placed in the TA-20?
With a screwdriver or snap?


----------



## hmscott (Dec 23, 2021)

cirodts said:


> just for curiosity how do you release the crown where the valves are placed in the TA-20?
> With a screwdriver or snap?


The 2 - protective Metal Frame "Cages" around the tubes up top are a simple 2-legged "plug-in" that is held in with magnets in the legs.  It only "hovers" above the tube with a small air gap - there is no contact with the tubes.

They are easy to pull out and set aside when changing tubes.  They are made with light aluminum with little mass so they don't hold much heat nor for long, when the TA-20 is powered off they quickly cool to the touch.


----------



## cirodts

so they can be easily extracted without a screwdriver, I would like to extract the right one because it makes a little noise when I put a valve in it.


----------



## hmscott (Dec 23, 2021)

cirodts said:


> so they can be easily extracted without a screwdriver, I would like to extract the right one because it makes a little noise when I put a valve in it.


Ah, I see, are you talking about a "Guard" around the socket?

*Update* - There isn't anything around the socket - the sockets are soldered into the PCB without anything else around it.  Your photo suggested a ring around the socket, but it was the beveled edge of the metal top plate reflecting the light.

I haven't taken the Xduoo TA-20 apart, but previous Vacuum Tube PC boards I've seen have that metal shield held on with "tabs" formed into the metal going through the PC board, and either twisted with a pliers to hold them in place, or the "tabs" are soldered onto a pad to hold it in place.  (Perhaps this method was ended decades ago  )

That is a bit weird that the shield isn't more centered around the socket - that's the point of the tabs going into the PC board holding the shield centered in place.

Let me see if I can find a representative photo showing what I am trying to describe in words. 

Of course the first photo I find is a riveted shield onto a socket 



The kind I was describing were 2 piece socket/shield parts independently attached to the PCB...which is what your top down photo of the TA-20 socket / shield looks like - a "one-piece" riveted part in the photo above and below would be "pre-centered" and unlikely to be askew as your photo shows.

I've looked for a TA-20 PCB with those 2 sockets / shields, but all I find are photo's of the bottom of the PCB under the bottom plate.

I could ask Xduoo, but I think they are away for their Holiday/Vacation - I haven't gotten replies this week from them yet, probably won't hear back till next week or until after the 1st.

*Update: *@cirodts , in the Xduoo marketing materials I see Xduoo shows a photo of the tube / socket PCB, and oddly enough, there is no shield...

https://xduoo.net/product/xduoo-ta-20/

You might unplug your TA-20 and using a long nose (thin tines) pliers or a long nose tweezers see if you can move that shield independent from the socket, perhaps it is loose?

*Update:* No, please don't do that   There isn't anything around the socket.  The sockets sit naked on the PCB - soldered to it.  Please leave the socket be.


----------



## hmscott (Dec 23, 2021)

hmscott said:


> Ah, I see, the "Guard" around the socket.  I haven't taken the Xduoo TA-20 apart, but previous Vacuum Tube PC boards I've seen have that metal shield held on with "tabs" formed into the metal going through the PC board, and either twisted with a pliers to hold them in place, or the "tabs" are soldered onto a pad to hold it in place.  (Perhaps this method was ended decades ago  )
> 
> That is a bit weird that the shield isn't more centered around the socket - that's the point of the tabs going into the PC board holding the shield centered in place.
> 
> ...


@cirodts - I looked at my TA-20 with a flashlight into both tube socket holes in the top plate of the TA-20, and there is nothing in there to rattle, no shield, only the naked socket soldered to the PCB.

So are you saying the socket / PCB assembly makes stress creaking noises while applying pressure to insert / extract the tubes?

I hear that too sometimes if I press too hard - or the tube pins are too corroded - that's why I like buying new tubes with gold plated pins - those slide in / out with less force.

I wiggle the tube side to side, not so much wiggle as "tilt" the tube ever so slightly side to side and then change directions and tilt it side to side the other way while pulling/pushing with gentle force.

Patience helps, I let it happen slowly, then it will release and just "pop/drop out", no squeaking from the socket or the PCB...

It would be a pain to replace the tube sockets soldered onto the PCB, so I take each tube removal/insertion slowly, and I'll hopefully nudge semi-infinite insertions/extractions out of those sockets.


----------



## cirodts

thank you very much for the explanation, my fear is that that little creak may cause the welds to break.


----------



## hmscott (Dec 23, 2021)

cirodts said:


> thank you very much for the explanation, my fear is that that little creak may cause the welds to break.


It is probably not the solidly soldered socket pins, instead it is usually the fasteners used to connect the PCB to the chassis, or in this case to the other PCB below the tube/socket PCB:



I highlighted in Yellow the 4 - bolt/screw/nut pairings at the 4 corners where the stress is passed, I would expect those fasteners are where the creaks are coming from.

The sockets are strong - as are the pins passed through the PCB - soldered on both sides of the holes the pins passthrough (pcb through-hole).  There is also a "spacer" the bolt is going through to raise the socket PCB above the main PCB - there could be noise generated by the stress of the force applied to those bolts going through the "spacer" too, or the lock washers against the PCB.

The socket tines that open to accept the tube pins can also make a noise, scraping the pins against them also can make a noise, but usually the actual tube pin to socket noise is very hushed.

Again, I hear these same sounds occasionally and when I hear them I - breath out - relax - and use a little less force and add a little more time / patience to the task 

*Hmmm*, I hope Xduoo put a support under the middle of that tube socket PCB, connecting to the PCB under it - like the 4 corners.  That is a long enough span that could cause the socket PCB to "bend" down at the middle as pressure is applied unless a center bolt/spacer takes the pressure...


----------



## cirodts

in fact I believe and hope this is it The socket tines that open to accept the tube pins can also make a noise, scraping the pins against them also can make a noise, but usually the actual tube pin to socket noise is very hushed.


----------



## PetFju (Dec 23, 2021)

i actually considered ordering some new tube sockets while i was at it ordering some new caps for the TA-20. Then i decided i have plenty of time to do that whenever they're worn out, and didn't bother. 
However; i did order some new signal caps for the TA-20. Unfortunately really good ones won't fit inside the chassis, so it had to be "lower end" good brands. 
I got one set of 8.2uF 400Vdc Jantzen Standard Z-Cap Capacitor and one set of 8.2uF 250V Mundorf MCap MKP Classic Capacitor , as they are recognized brands with units that'll ctually fit. And also might just up the sound a tiny bit 

Does anyone have any experience modding these amps in any way like this, and if so; what's your findings?


----------



## cirodts

hallo, I made a video of my problem, noise when applying the valve, what can it be?


----------



## hmscott (Dec 24, 2021)

cirodts said:


> hallo, I made a video of my problem, noise when applying the valve, what can it be?



Definitely a "tick" sound, a distinctly different sound than the socket tines scraping by the tube pins, but both are sounds that I am not hearing.  You have the Microphone close to the TA-20, closer than my ears, so when I put in tubes I don't hear anything of note, unless I am "not gentle" - thoughtlessly pushing in the tube, as when I am in a hurry.  But that sound is a "creak", which I don't hear on your video/audio.

I've heard similar "ticks" when hardware isn't tightened down.  Or more accurately, I have heard "ticks" and "clicks", like a screw / nut not tightened fully - enough to be considered "close enough", but there is still one "tick" of play in the fastening hardware.  I've cured those by going in and tightening all the hardware I can find around the stress point I am compressing.  Nut driver in hand, screw driver set at the ready, and zip up all the hardware, and that gets rid of the sound.  I've occasionally found a rivet not completely punched and then I have to replace the whole assembly (socket in this case).

Where did you buy your TA-20?  Do you still have time in your return period?  Perhaps this is a known thing, not a problem, you could send a link to that video to your seller support email and ask if it is something to be concerned about, as it is concerning enough to you to ask.


----------



## cirodts

hmscott said:


> aaa
> 
> Definitely a "tick" sound, a distinctly different sound than the socket tines scraping by the tube pins, but both are sounds that I am not hearing.  You have the Microphone close to the TA-20, closer than my ears, so when I put in tubes I don't hear anything of note, unless I am "not gentle" - thoughtlessly pushing in the tube, as when I am in a hurry.  But that sound is a "creak", which I don't hear on your video/audio.
> 
> ...


Hi, if you turn up the volume of the video you will hear between a tick between a hook and the other of the tube.


----------



## hmscott (Dec 25, 2021)

cirodts said:


> Hi, if you turn up the volume of the video you will hear between a tick between a hook and the other of the tube.


Does the same "tick" sound happen when installing in the other tube socket?  And, does the sound happen when you swap the tubes - try the other tube in the "noisy" socket?

I can't get close enough to my TA-20 to hear much of any sound from tube insertion/removal - I don't hear the "tick".

Does anyone else hear a "tick" when inserting a tube in their TA-20?


----------



## cirodts

it ticks only on the right side of the ta-20 even if I switch the valves.


----------



## hmscott (Dec 29, 2021)

cirodts said:


> it ticks only on the right side of the ta-20 even if I switch the valves.


It's likely a tube socket riser board support fastener not tightened fully, I don't see one, but a "ring clip" not fastened properly with room to move can also "tick" as the pressure exerted meets the bottom of the travel and is transferred to the attachment clip.

Without taking it apart and tightening all the fasteners on that side - I wouldn't have anything else to recommend right now.

Perhaps there is also a "clip" used to lock the socket in place for soldering - there might be a physical attachment to hold the socket in place before soldering it - although the friction of the 9 pins might be enough to hold them in place for soldering.

There should be no travel possible after soldering all 9 pins - no movement of the socket possible - so I am back to the fasteners at the edge of the PCB on that side or underneath - if there is mid-span support for that socket PCB.

I wouldn't worry about it, but if it bugs you, see if you can RMA it to the dealer/Xduoo for inspection - or if you can still return it to the seller, best option, then return it and swap it for another new one.   That's what I would do myself if it bothered me enough.

Happy Holidays!


----------



## hmscott (Dec 25, 2021)

dsrk said:


> It's normal, I hear the pop too every time I turn it off.





devin.oct said:


> Thanks, so is it better to unplug headphone first before turning off?





CADCAM said:


> My 602 also has a nasty pop when you turn the unit off, I unplug my headphones every time I remember. I don't understand why this wasn't addressed by Xduoo during development/production of this amp. Long term affects of the pop and the extra unplugging and plugging of the headphones...





waveSounds said:


> Thanks for that, @hmscott. Really helpful stuff! I actually already have an IEMatch but hadn't thought about using it with this amp until you mentioned it. I've just plugged it in (set to ultra) so we'll see what happens when it's time to flip the power switch in a bit. At the very least, it has expanded my usable volume from just below 9 o'clock with a significant decrease in source volume to boot, to 12 o'clock and only a minor decrease in source volume. A small win, eh!


I received a reply from Xduoo:

"Hi, Scott
Here is an article on how to solve this problem：
https://www.audiosciencereview.com/...gging-in-headphones-dc-offset-tutorial.25470/
We also noticed this problem and solved it
*Best Regards"*

After reading through the procedure, I would feel comfortable doing the adjustment myself, but I wouldn't recommend to anyone else to take that on unless you are an experienced professional - there are too many things that can be unknown to someone the first time they work on live voltage bare components.

Also, I wouldn't use a screw driver to make the adjustment, too easy to slip and zap yourself. Instead get a non-conducting tuning tool.

I've sent an email to Xduoo...


----------



## Galapac

hmscott said:


> I received a reply from Xduoo:
> 
> "Hi, Scott
> Here is an article on how to solve this problem：
> ...


Good advice. I personally poke around with a chopstick myself.
Always unplug your unit and let it rest for at least a half hour.
Never use 2 hands to poke around inside, best to leave one hand in your pocket. You could create a ground and stop your heart, seriously.
If you know how you can always discharge your caps with a multi meter connected to a resistor to safely discharge.
Many YouTube’s vids on this procedure and safer once the caps have no juice.
Wear rubber soled shoes.
Remove any jewelry beforehand.

If I scared you a bit then I did my job as electricity is nothing to fool with.

If you do decide to open the amp up, read/watch instructional videos first until you feel comfortable or entrust it to someone with experience.


----------



## cirodts

hmscott said:


> It's likely a fastener not tightened fully, I don't see one, but a "ring clip" not fastened properly with room to move can also "tick" as the pressure exerted meets the bottom of the travel and is transferred to the attachment clip.
> 
> Without taking it apart and tightening all the fasteners on that side, perhaps there is also a "clip" used to lock the socket in place for soldering - there might be a physical attachment to hold the socket in place before soldering it - although the friction of the 9 pins might be enough.  But, there should be no travel possible after soldering all 9 pins - no movement of the socket possible - so I am back to the fasteners at the edge of the PCB on that side or underneath - if there is mid-span support for that socket PCB.
> 
> ...


thanks, Happy Holidays.


----------



## hmscott (Dec 29, 2021)

hmscott said:


> Well, tube only amps will give more "tubey" sound, but I've found the 12AT7 Mullard's of the links I've shared, in my TA-20, have given the widest sound stage and most focused sound for directionality - instrument and "enemy" placement, while being not too expensive.
> 
> I've ordered these Mullard E180CC tubes, and will report back when I hear them, I'm hoping they are the 12AT7 version of the E80CC tubes:
> 
> ...


A quick after Xmas update - What I got for Xmas this year.  

The 5 - E180CC Mullard tubes arrived at the local Post Office (From Great Britain), Dec 25th... sigh...expecting delivery on Dec 27th 

I had a nice surprise in an email from Xduoo Nov 27th:

"Hi, Hmscott
yes, thanks.
As a feedback, I can give you a TA-26, if you like it
*Best Regards,"*

I hadn't asked for anything, they simply offered it as thanks for my feedback.  Of course, I said YES!!

I received the TA-26 on the 23rd and opened it yesterday evening...and here are my first impressions:

After digging through my headphone bags/boxes, I found my 6.35mm cables, removed the 4.4mm balanced cables, and tried out the TA-26 using the Topping D90 MQA.

At first it was "different", these are new tubes - they look like the standard China tubes Xduoo is famous for, and after swapping headphones around for a while:

Hifiman HE6SE V2, almost but not quite enough power - up to 80% on the TA-26 volume dial - The TA-20 delivers better power and experience.

Hifiman Ananda, wow, even at first play - I had to turn down the volume to 25% - the sound is full and encompassing, initially with some sharp tinges, but those went away after a few hours of listening.

Beyerdynamics DT770 Pro 16 ohm, that impedance is too low for the TA-26 - 60ohm-600ohm - so I'll try my DT880/600ohm and DT990/600ohm later and report back.

The Hifiman Ananda sounded so amazing on the TA-26 even with the stock tubes, that I didn't want to swap the Ananda out for any other headphones/IEM's.  And, that was on movies (HBOMAX - Matrix Resurrections) and Youtube videos, but then when I listened on Tidal is when I was truly in appreciation of the TA-26 sound.  The TA-26 SLAM! is unlike the TA-20, far more impactful and the "airy" sound I enjoy comes through on the Ananda's in excess to what I hear on the TA-20.  And, that is with the stock tubes...

And, yes, of course I've already spec'd out a couple of new Mullard's for the TA-26, but before I pull the trigger on them does anyone with the TA-26 have any suggestions for tube pairings?  I'll go back in this thread and start researching elsewhere for TA-26 tube ideas.  I'll update here on what I find and enjoy.
Right when I thought I'd found the last tubes I'd need for my TA-20, Xduoo sucks me back in with the TA-26; I see what you did there. 

Thanks to Xduoo for their kind gesture, and you can all be sure I'll not go too easy on Xduoo from here on out.  

*Update: *Setting -12.0dB output on the Topping D90 MQA DAC, and the sharpness is gone and the TA-26 sounds Sweet 

New Update: after listening in both -12dB and -0.0dB, I enjoy both at different times.  It is nice with -12dB to be able to have more Volume Control range on the dial when I want to rock out, but the 0.0dB stock setting is also useful, but not when I want to increase volume gradually - there isn't enough Volume Control movement room.

*Update:* The TA-26 is an upgraded/modernized Darkvoice _homage_, using the same tubes: *Darkvoice 336i & 336SE Tuberolling PartII*

*Update: The Mullard Holland made E180CC tubes arrived and are installed in the TA-20, WOW!  More later...*


----------



## cirodts

hmscott said:


> A quick after Xmas update - What I got for Xmas this year.
> 
> The 5 - E180CC Mullard tubes arrived at the local Post Office (From Great Britain), Dec 25th... sigh...
> 
> ...


you can try the ta-20 IN full BALANCED compared to the ta-26 who sounds better?


----------



## hmscott (Dec 28, 2021)

cirodts said:


> you can try the ta-20 IN full BALANCED compared to the ta-26 who sounds better?


Too early to tell, and until I get the Mullards or other NOS tubes in the TA-26 it is an unfair comparison overall.

I will say they both sound very different, the TA-20 SS amp section reduces the "airy-ness" on the TA-20, while the TA-26 is pure tube bliss... with the sharp edges of new tubes keeping my from declaring the TA-26 over the TA-20, in anything. *-- It turns out I was overdriving the TA-26 with my D90, adding -12dB attenuation cleaned up the TA-26 audio completely, now it is smooth and sweet--Now, I don't need to reduce the D90 output, I guess the tubes "warmed up" *

The stock tubes on both the TA-20 and TA-26 are too sharp out of the gate, and need burn in, the longer the better - I've read/heard 50-200 hours.  At least that is what others report that stick with the stock tubes long enough to reap the rewards.

I bought new issue tubes for the TA-20 so when it arrived I could swap out the stock tubes.  For the TA-26 it will be a couple of weeks before I select/order/receive replacements, so I will endure the stock tubes, I am enjoying the TA-26 that much.

But, at this stage, I'd say there are definite headphones/IEM's that won't be compatible with the TA-26 due to impedance -  as I've already found, which is why I selected the TA-20 Balanced Tube with SS output for wide impedance compatibility, and there will likely be music / source material I'll still prefer on the TA-20 Tube/SS vs Tube only - but that could eventually lean in the TA-26's direction with better pairings of NOS tubes.

Like I said, too early to tell


----------



## cirodts

Isn't the balanced ta-20 as airy as the unbalanced ta-26 with both having stock tubes?


----------



## hmscott (Dec 26, 2021)

cirodts said:


> Isn't the balanced ta-20 as airy as the unbalanced ta-26 with both having stock tubes?


No, the TA-20 stock tubes weren't airy, it was more SS than Tube sound - I did immensely enjoy the stock tubes compared to my Topping A90, and when I swapped in the first PSVANE 12AU7 matched pair, that was it, I was hooked on the TA-20.

So I ordered new issue 12AU7 tubes, a couple PSVANE series, Genalex Gold pin, JJ Electronics regular and gold pin, Telefunken - all 12AU7's, and then started into finding NOS tubes, gradually finding my footing through talking with friendly Tube dealers - until I decided to try a 12AT7 

That was another turning point for me, the 12AT7 really bumps up the air and Slam from the TA-20, with the 12AX7 being a bit too "Hot".

The stock tubes on both the TA-20 and TA-26 are good for confirming functionality after delivery, and provide an increasingly enjoyable listening experience - time / burn-in for the tubes and electronics mellows the sound as reported by others, but I am too interested in hearing the best both headphone amps can provide to keep the stock tubes running long enough to give them their due.

I will say I am happy I heard the stock tubes, then did the gradual incremental listening experience of going through all the intermediate steps / tubes over the last year+.  I don't think I'd recommend "jumping in with both feet" right away - give yourself the enjoyment of the full longer term listening experience of gradually trying many NIB/NOS tubes, starting with 12AU7/equivalents then 12AT7/equivalents.

Or, order some NIB/NOS 12AT7 Mullards that I've linked before a few times, and jump right to the best tubes I've found so far for the TA-20.  There are lots of dealers on ebay and elsewhere that sell those same NIB/NOS Mullard 12AT7 tubes - from the 50's-80's - they aren't difficult to find - the 50's/60's built Mullard 12AT7's sound great to me - and you can also skip the intermediate expenses of purchasing all those other tubes I've tried on the path to the Mullards. 

The TA-26 stock tubes are extremely airy in comparison to the Mullard 12AT7's on the TA-20, but are a bit sharp as new out of the box, it would take a lot of run time to then judge those tubes against equally run NIB/NOS tubes in a fair comparison.

Again, all too early to tell, I've only got about 6-8 hours on the TA-26! 

*Update:* Started looking for video reviews / tube rolling advice for the TA-26 (Darkvoice uses same exact Chinese stock tubes), and DMS has a good start on the path for tube rolling the Darkvoice and a Little Dot tube headphone amp that kind of echoes my thoughts on the stock TA-20 tubes vs stock TA-26 tubes.  Every little bit of info gathered from others experience can provide help on finding what you will really enjoy.

I did try what DMS suggested for using the D90 on the Darkvoice (same tubes as the TA-26), to turn down the D90's output a bit, I've attenuated it by -15dB, and the sound is less sharp - suggesting the D90 4V is overdriving the TA-26 input; that reduction in drive requires moving the volume dial on the TA-26 from 25% to 35% - I'll ask Xudoo what the maximum recommended input drive voltage is for the TA-26.

When I asked Xduoo the same question about the TA-20, Xduoo replied that the TA-20 can take 8V on the inputs, and the D90 is 4V, so I ran/run the D90 at full output for the TA-20:

January 4, 2020, relayed through Hifigo from Xduoo:
"Hello, Scott, sorry for late reply, they have 3days holiday here.
Xduoo reply below 8V is all no problem. if it is above 8v, it will cause distortion."

I'll report back what Xduoo recommends for the maximum input voltage for the TA-26


----------



## cirodts

the 12AT7 and 12AX7 are not suitable for the TA-20 or am I wrong?
I only use 12au7 for safety.


----------



## hmscott (Dec 27, 2021)

cirodts said:


> the 12AT7 and 12AX7 are not suitable for the TA-20 or am I wrong?
> I only use 12au7 for safety.


Xduoo has confirmed that the 12AT7 and 12AX7 were ok to use in the TA-20 before I tried it myself.  You could email service@xduoo.net to ask the same question so you can hear it direct from Xduoo.

December 14, 2020, relayed through Hifigo from Xduoo:
"Hi Scott, sorry for late reply.
...is it possible to substitute the 12AU7 with 12AT7 or 12AX7 : Xdoo reply yes no problem."

I also confirmed with Xduoo that the E80CC is compatible before I plugged in a pair of E80CC's.  I was concerned because the E80CC, even though it is a 12AU7 variant the E80CC draws 2x the heater current of the 12AU7, and Xduoo said:

August 4, 2021, relayed through Hifigo from Xduoo:
"Hello, Scott,
Sorry for late reply.  E80CC ( 6085 ) is ok to match with TA20 and TA30 xduoo replied,  and they thank you for your questions and testing.
If you have any futher questions, pls let me know.
Best regard ~ "

The TA-20 runs warmer with the E80CC's, but not as hot as the stock tubes on the TA-26, I guess I should post what the temps are on the TA-26:

The TA-26 6N8P Preamp tube measures *115F*, the 6N5P "buffer" measures *143.8F* - the front panel measures *86.7F*, the top of the Transformer box measures *90.2F* - Ambient temperature is 72F, using an infrared thermometer set to measure "Objects" / not "Bodies".

I've already posted the TA-20 temps, and it is powered off right now...

Update: Settling on -12.0dB output on the Topping D90, the Stones sound Sweet on the TA-26 + Hifiman Ananda, volume set to 35%-50% on the TA-26... 

Rolling Stones - Beggars Banquet - 1968
https://tidal.com/browse/album/77735208

Crosby, Stills, & Nash - 1969
https://tidal.com/browse/album/306604

Diana Krall - The Girl in the Other Room - 2004
https://tidal.com/browse/album/64325935

Diana Krall - California Dreamin' - 2013
https://tidal.com/browse/track/51070811
https://tidal.com/browse/album/51070810

Diana Krall - The Look of Love - 2001
https://tidal.com/browse/track/576622
https://tidal.com/browse/album/576613

Diana Krall - This Dream of You - 2020
https://tidal.com/browse/album/155663945

*Update:*  A nice review of the TA-26 here on head-fi:  xDuoo TA-26: a perfect match for my Sennheiser HD 650, and more posts in that thread.

*Update:* Zeos's Xduoo T26 Comparisons/Reviews...:
⭐⭐⭐⭐⭐Xduoo TA-26 _(Z Reviews)_ --Start of Tube Week--
Miltra OTL PCL86 _(Z Reviews) (vs TA-26, and Zeos keeps favoring the TA-26)


----------



## PetFju

@hmscott ; You seem to have had a lucky strike there with xduoo  Happy for you, and that is an awesome thing for them to do! 
I am interested in trying a "full tube" myself, so it is interesting hearing your impressions and opinions on the matter 
Btw; I did order another set of tubes for the TA-20, Tung Sol Black glass 12AU7. Looking forward to testing them, but i think that'll be it for a while. I have spent more on tubes than the amp at this point..lol


----------



## hmscott (Dec 27, 2021)

PetFju said:


> @hmscott ; You seem to have had a lucky strike there with xduoo  Happy for you, and that is an awesome thing for them to do!


Thank you! Xduoo are awesome 


PetFju said:


> I am interested in trying a "full tube" myself, so it is interesting hearing your impressions and opinions on the matter


I'd say go for it.  Even the TA-26 stock tubes sound great now that I've reduced the output drive from the Topping D90 MQA DAC to -12dB, before - to me - it sounded overdriven with the full output of the D90 MQA into the TA-26, it made the TA-26 "sharp" which I was attributing to the new tubes.  Now they sound Sweet 

I'm finding I enjoy both the Hybrid Tube/SS TA-20 along with the TA-26. They complement each other for listening with different headphones / IEM's, and their sound characteristics are different enough there is no "sameness" comparing similar material side by side.


PetFju said:


> Btw; I did order another set of tubes for the TA-20, Tung Sol Black glass 12AU7. Looking forward to testing them, but i think that'll be it for a while. I have spent more on tubes than the amp at this point..lol


Wow!, that's awesome, Congratulations - those Tung-sol Black Glass 12AU7's are tough to find new @ 100%!


----------



## hmscott (Dec 28, 2021)

Interestingly, while the Hifiman HE6SE v2 are driven better by the TA-20, my Beyerdynamic DT880SE 600ohm are far better sounding on the TA-26, with a big wide sound and plenty of dynamic range - and more than enough power.  Really nice.  I didn't know what I was missing!

And, I'm not sure now I need to reduce the output on the D90, as I have -0.0dB set on the D90 and the DT880SE 600ohm has clear sweet audio.

I still have the DT990SE 600ohm, Sendyaudio Aiva, Sennheiser 660s, and a few more to break in on the TA-26.

The TA-26 stock tubes really do sound great now.


----------



## cirodts

hmscott said:


> Interestingly, while the Hifiman HE6SE v2 are driven better by the TA-20, my Beyerdynamic DT880SE 600ohm are far better sounding on the TA-26, with a big wide sound and plenty of dynamic range - and more than enough power.  Really nice.  I didn't know what I was missing!
> 
> And, I'm not sure now I need to reduce the output on the D90, as I have -0.0dB set on the D90 and the DT880SE 600ohm has clear sweet audio.
> 
> ...


you wrote: while the Hifiman HE6SE v2 is driven better by the TA-20, but are you referring to BAL or SE?


----------



## cirodts

best pairings headphones-TA-20?


----------



## PetFju (Dec 28, 2021)

cirodts said:


> best pairings headphones-TA-20?


I think the answer to that will be as diverse as the people answering tbh. As long as the headphones aren't insanely hard to drive or are crappy in general, i think you'll be happy with the amp  My experience with it so far only includes Hifiman Sundara, Sennheiser HD58X jubilee, Philips Fidelio X2, Beyerdynamic DT700 PRO X and Shure SH940. 
And the amp doesn't in any way "eq" the headphones, it doesn't impress its own sound onto the headphones, rather some smaller details can be adjusted with different tubes, but the sound in general is pretty neutral. 
I guess what i am trying to say here is that the source (dac,  file quality etc) and the soundsignature of the actual headphone will matter more, as the amp in my opinion is basically a solidstate amp with a little bit of tube flavoring to be tilted a bit in the direction the owner desires. 
That flavoring though, will not change the sound of the headphones, if that makes sense. 

However; this all wasn't really a straight answer for you, but i think all my cans sound good on this amp, and i don't think i need something "better" to get the best out of most medium and medium-highly priced headphones.


----------



## hmscott (Feb 27, 2022)

cirodts said:


> you wrote: while the Hifiman HE6SE v2 is driven better by the TA-20, but are you referring to BAL or SE?


It doesn't matter, the TA-20 specifications show 2000mw for both Balanced and Single-ended.  To me, between the two choices, there is a center focus pull to the Single-ended sound, so I prefer the Balanced mode sound on the TA-20 and have converted all of my cables to 4.4mm or 4-pin balanced because of the higher power delivery on the FiiO M15 and Topping A90, and 2.5mm on the BTR5.  The TA-20 has the same power delivery on both 4-pin balanced and 6.35mm Single-Ended.

On the TA-26 there is only one choice, Single-ended, but the image presentation doesn't sound to me as "pulled in to the Center" as Single-ended on the TA-20 - after listening for a couple of dozen hours my ears are used to the presentation, and Single-Ended sounds as wide and detailed as Balanced on the TA-20.


cirodts said:


> best pairings headphones-TA-20?


The whole reason I bought the TA-20 is due to the Hybrid Tube/Solid-State design, which drives a wider range of IEM/headphone impedance, so there is less of a "compatibility" limitation with the TA-20 (8ohm-600ohm) as I've found on the TA-26 (60ohm-600ohm).

The 16 ohm DT770 didn't "sound right" on the TA-26 but the DT770 16 ohm sounds great on the TA-20.  The 600 ohm DT880SE sounds "amazing" on the TA-26, and only "good" on the TA-20, after comparison with the TA-26. The TA-20 doesn't have enough power at 600ohm to make the 600 ohm headphone "pop" like on the TA-26.  I'm looking forward to hearing my Sennheiser 120ohm/300ohm headphones on the TA-26.

And, I haven't tested IEMs, or mid-range 120ohm-300ohm headphones on the TA-26 yet.  So, I've not completed testing/comparing the TA-26 vs TA-20. The TA-26 has that 60ohm low-end impedance range.  IEM's 60ohms and under - most of them(?) may not sound as good on the TA-26 as on the TA-20, similar to what I heard with the DT770 16 ohm headphones on the TA-26.

On the TA-20, after I solved EMI/RFI and PC/GPU noise issues with Mogami 2534 QuadStar cable built by WBC, and the iFi iDefender+ on the USB input to the D90.  IEM's which in general have a lower range of impedance than headphones, as well as higher sensitivity to system noise levels, sound great to me on the TA-20 - with a noise-free black background.  The TA-26 has a noise-free quiet background on my headphones tested so far, but I've not tried sensitive headphones/IEM's on the TA-26 yet.

The TA-20 in either Bal/SE does great for all of my lower impedance IEM's and headphones, on up to 600 ohm, where most amps start to "fade" in power to drive 600 ohm headphones, the TA-20 drives headphones across the entire impedance range.  As compared to the TA-20, the TA-26 has more "power/drive" on my 600 ohm DT880SE - it sounds "glorious", very tubey - even with the stock TA-26 tubes.

The TA-20 Hybrid Tube/SS design does a great job with IEM's, dynamic, BA, piezo, planar, hybrid designs, and also sounds great with dynamic, and planar headphones.  They all sound great, and I've not been disappointed with anything I've listened with on the TA-20.


----------



## AudioCats

a different TA-26 on ebay? or the same?
https://www.ebay.com/itm/3042806079...oQ5TFU3A2A%3D%3D|clp:2334524|tkp:BFBMsoKdzcBf


----------



## alexeyi (Dec 29, 2021)

It is the same model. I purchase one of these two months ago from a local supplier in Europe and it is decent.

LE:
@vmiguel I sent you a PM with the link.


----------



## vmiguel

alexeyi said:


> It is the same model. I purchase one of these two months ago from a local supplier in Europe and it is decent.


Can you give a link, please?
TIA


----------



## hmscott (Dec 29, 2021)

AudioCats said:


> a different TA-26 on ebay? or the same?
> https://www.ebay.com/itm/304280607988


Yup, they added on a couple of bucks - list price is $319, comes from China.  Do you know the seller?

IDK if there are authorized dealers for Xduoo on eBay?  You might ask the seller you want to buy from if they handle warranty claims or do you end up needing to go direct with Xduoo for service?

Xduoo sells direct, with Paypal:
https://xduoo.net/product/ta-26/

I normally buy from Hifigo.com as they have great shipping sense - picking the best carrier at the time to get here in the US the quickest, I always get my stuff quickly - as quick as the best route available during the pandemic.  Sometimes DHL isn't the fastest, so Hifigo.com uses Fedex.com or other Chinese carriers - using USPS "last mile" from port (LA/Oakland).  https://hifigo.com/products/xduoo-ta-26-tube-headphone-amplifier-pre-amplifier

Xduoo shipped my TA-26 via DHL - not sure what shipping service Xduoo's direct sales uses to your location. Mine was shipped on Dec 17th from China, received by DHL Hong Kong on 21st, and arrived on Dec 23rd in US @ San Francisco DHL, and to me same day on Dec 23rd, so my TA-26 got here as quick as anything else I've bought direct from China. 


alexeyi said:


> It is the same model. I purchase one of these two months ago from a local supplier in Europe and it is decent.
> 
> LE:
> @vmiguel I sent you a PM with the link.





vmiguel said:


> Can you give a link, please?
> TIA


Which Xduoo dealer in Europe?  You might as well share the link(s) with everyone here


----------



## alexeyi

hmscott said:


> Yup, they added on a couple of bucks - list price is $319, comes from China.  Do you know the seller?
> 
> IDK if there are authorized dealers for Xduoo on eBay?  You might ask the seller you want to buy from if they handle warranty claims or do you end up needing to go direct with Xduoo for service?
> 
> ...



Sure, the place where I bought the equipment can be found under the name of Muziker


----------



## PetFju (Dec 29, 2021)

Which one to try in the TA-20...Any advice/experiences?
Edit; I went with the Mundorf caps, as the Jantzen were a tighter fit. So i'll try these for a while, and then change


----------



## PetFju (Dec 29, 2021)

So far i have to be honest, i don't hear much of a difference. If anything there might be a tiny bit bigger soundstage, but that could easily be chalked up to expectation bias..
But i'll listen like this for a while, then swap the Mundorf caps for the Jantzen and hear if i can pick out any differences. This is what is fun about this hobby to me, and also why i don't buy more expensive equipment. It's more fun (and less hazardious to my wallet..) to tinker with the equipment to see what one can get out of it


----------



## hmscott (Dec 30, 2021)

PetFju said:


> Which one to try in the TA-20...Any advice/experiences?
> Edit; I went with the Mundorf caps, as the Jantzen were a tighter fit. So i'll try these for a while, and then change


Thank you for the awesome photo's of the interior boards and wiring 

I know it isn't your focus, but next time you have your TA-20 disassembled, can you please check out the riser board that holds the tube sockets, for a couple of things?

First, does that riser board have a support between it and the base board in the middle of the board?

The 4 corners have bolts,nuts, but does it also have a "spacer"?

Would you please photograph the edge on view so we can see the base board edge, bolt/spacer, and riser board assemblage, along with see the middle of the riser board gap to see what support there is in the middle of the base/riser board.

It would be helpful to also see an edge on view of the socket, whether there are "pins" off the sockets that go through the riser board and are soldered on both top/bottom, or if there are "tabs" off the socket that only solder to the top of the riser board.

And, if one/both of the bolt/screw "nut" pairs are loose on one side of the riser, is there movement of the board/socket when inserting a tube in that side's socket?

That is all for @cirodts and others noticing a "tick" when inserting a tube on one or both sides of their TA-20, it would be fun to figure out what might cause that tick by recreating it on a TA-20 that is getting opened on a semi-regular basis to test mod's.

What also might be interesting is to change the values of the caps, you have several of the same value, it would be interesting to solder them in parallel or solder them in series - changing the value - I wonder if those changes would be "more audible" than manufacturer/model/material changes?

Also, another fun project would be to calculate/reference the tube resistance/capacitance interace values to match the tube characteristics more exactly for the change from 12AU7 to 12AT7 - and perhaps 12AX7 - as well as E80CC/E180CC - as the 12AT7/12AX7/E80CC/E180CC tube swaps might sound "different" if correctly "tuned" tube interface values were used?

Of course, the inbalance of interface component value tuning might be what makes the swap from the 12AU7 to a 12AT7 sound so intriguing?


----------



## PetFju

hmscott said:


> Thank you for the awesome photo's of the interior boards and wiring
> 
> I know it isn't your focus, but next time you have your TA-20 disassembled, can you please check out the riser board that holds the tube sockets, for a couple of things?
> 
> ...



From what i remember seeing, there is no supprt in the middle of the riserboard. Also, there are no lockwashers on the nuts that are holding it onto the standoffs from what i could see. So there is a real possibility for the nuts to loosen over time, or if they weren't tightened sufficiently in the first place. 



hmscott said:


> Would you please photograph the edge on view so we can see the base board edge, bolt/spacer, and riser board assemblage, along with see the middle of the riser board gap to see what support there is in the middle of the base/riser board.
> 
> It would be helpful to also see an edge on view of the socket, whether there are "pins" off the sockets that go through the riser board and are soldered on both top/bottom, or if there are "tabs" off the socket that only solder to the top of the riser board.
> 
> And, if one/both of the bolt/screw "nut" pairs are loose on one side of the riser, is there movement of the board/socket when inserting a tube in that side's socket?



I'll take those (and better) pictures the next time i open the thing up, from all angles.
And i'll check if there is any play in the board, but i am certain there will be if one or more of the nuts are loose.



hmscott said:


> What also might be interesting is to change the values of the caps, you have several of the same value, it would be interesting to solder them in parallel or solder them in series - changing the value - I wonder if those changes would be "more audible"?



I am not too keen on changing the capacitance all that much considering i don't know what to expect from doing so. I am no electrical engineer, i am just a curious dude with a soldering iron.. 



hmscott said:


> Also, another fun project would be to calculate/reference the tube resistance/capacitance interace values to match the tube characteristics more exactly for the change from 12AU7 to 12AT7 - and perhaps 12AX7 - as well as E80CC/E180CC - as the 12AT7/12AX7/E80CC/E180CC tube swaps might sound "different" if correctly "tuned" tube interface values were used?
> 
> Of course, the inbalance of interface component value tuning might be what makes the swap from the 12AU7 to a 12AT7 sound so intriguing?



This, unfortunately, is way "above my paygrade"...lol. If you know someone who can make these calculations (and comment on the effect of changing cap values) please let me know and i'll be the guineapig if it is not unsafe  Also, that might mean changing other components and their values, which is getting out there as far as potential benefit goes (to my knowledge).
But yea, you're probably right in that the amp can be tuned to work "better" with for instance the 12AX7 than it does atm.


----------



## AudioCats

hmscott said:


> Yup, they added on a couple of bucks - list price is $319, comes from China.  Do you know the seller?



hmm, they changed the price. I think it was $230 when I posted the link.


----------



## ColSaulTigh

Does anyone have any direct experience with the TA-30 vs. a Woo Audio WA7 (2nd or 3rd gen) or any other tube amps ~$1k USD?  I'm contemplating picking up something else for poops and giggles and curious if anyone has any other opinions.

Headphones in my signature.

Thanks!


----------



## AudioCats (Dec 29, 2021)

another listing.  Lets see if they change the price on this one as well.

(search ebay using "quality TA-26 6n5p 6n8p")


----------



## hmscott (Dec 30, 2021)

AudioCats said:


> another listing.  Lets see if they change the price on this one as well.
> 
> (search ebay using "quality TA-26 6n5p 6n8p")


Well, IDK, it's of course up to your own "things of interest", but I tend to ignore those strange unexplained "ebay phenomena" 

Usually I am focusing on finding what I need at a good price, from a reliable seller - then I try to get a "read" on that eBay seller - looking at what else they sell, to see if they focus on what I am buying for long term support, or repeatability should I want to purchase something else similar, or recommend them to someone else, or if it is an oddity in their "line of work".

To have prices change dramatically, change the name of the product - manufacturer hiding, would - to me - be "unreliable" in general, with exceptions it might be worth tracking down exactly what is going on.

There is no savings in costs if the end result isn't pleasant.

In this case they have a lot of successful transactions - *1762*, and no negative feedback showing recently.  All good measures of a seller for me.

So, in this case, I'd simply ask them directly.  Why are you selling so far below cost/MSRP?, and why are you calling an "Xduoo" Device a "Quality" Device.  Then quickly exclaim you are a serious buyer with cash on hand, but you are wary of the seemingly at odds points you've raised, and would like their answers before deciding whether to purchase from them, or not.

If they sell it at the loss, and it turns out to be a real Xduoo device that works - and didn't "Fall off of a Truck" - see if you can get the serial number from them before purchase to check with Xduoo (service@xduoo.net) and ask Xduoo if that is a "legit serial number" without encumbrances (was it reported stolen?)

There might be a perfectly reasonable explanation.  Like, "we can't sell for under MSRP using "Xduoo" as the name", and "we bought a pallet of TA-26's from a company in bankruptcy, and need to sell them quickly to recover working capital".

Please let us know how it works out for you


----------



## hmscott (Dec 30, 2021)

ColSaulTigh said:


> Does anyone have any direct experience with the TA-30 vs. a Woo Audio WA7 (2nd or 3rd gen) or any other tube amps ~$1k USD?  I'm contemplating picking up something else for poops and giggles and curious if anyone has any other opinions.
> 
> Headphones in my signature.
> 
> Thanks!


It is a bit of a reach, but I recalled that Sandu mentions his previous WooAudio WA6 Special Edition in his lead-in: xDuoo TA-30 Review – A Box Full of Surprises

"A lot of time passed since I listened an all tube amplifier at my place. I still have good memories of my former WooAudio WA6 Special Edition that I was upgrading monthly with better vacuum tubes and better capacitors, just to squeeze the best out of it."

Sandu also mentions details of burn-in requirements, with intermediate reads on the performance, so he knows what he is talking about.  So many today poo-poo burn-in, but having lived through a time where that was a normal part of manufacturing and sales - reminding customers to not immediately reject a product due to how it sounds out of the box, give it time to "burn-in", was a widely recognized truism.  Today there are devices that have components that don't "burn-in", but if any contribute to the audio path that do age over their "powered on time", they will indeed affect the resulting produced sound.  Tube amps are right there smack in the middle of being affected by "burn-in", and tubes continue to age and "burn-in" to the point of "going bad".   And, "Safety First", especially with devices that can kill you, several ways. 

"I. Burn-In requirements & Safety Precautions

Since TA-30 is full with high-grade Nichicon and Elna electrolytic caps and with some fat metal polyester film caps, plus that oversized transformer, it was mandatory running it in for at least 100 hours. As silly as it sounds, those driver tubes and the rectifier tube also need some burn-in, it is recommended at least 48 hours before making any critical listening. Another interesting fact is that TA-30 will sound at its best only after about 15 minutes of warm-up. I put TA-30 for a 7-day burn-in connected to a laptop that was playing tunes on repeat. I only turned it off at night since it is really hot to the touch after about one hour.

*At first it sounded closed-it, it was on the hotter side with brighter treble, there wasn’t any spaciousness, dynamics felt forced and really stiff. On week later, there is nothing of that left, spaciousness and transparency improved the most, bass made its appearance and finally it is sounding easy going and smooth.*

Having a higher gain and an impressive power output, TA-30 is on the hotter side if you crank that volume up. When I’m listening to Audeze LCD-4 at 11 o’clock position, TA-30 is hot to the touch, so I do not recommend putting it on top of another audio equipment, in direct sunlight or in tighter spaces. It should be used only in a dry and cool place with some extra room between it and other equipment. Please check the user manual and read the “Safety Directions” for a clear explanation."


----------



## ColSaulTigh

hmscott said:


> It is a bit of a reach, but I recalled that Sandu mentions his previous WooAudio WA6 Special Edition in his lead-in: xDuoo TA-30 Review – A Box Full of Surprises
> 
> Sandu also mentions details of break-in requirements, with intermediate reads on the performance, so he knows what he is talking about.  So many today poo-poo break-in, but having lived through a time where that was a normal part of manufacturing and sales - reminding customers to not immediately reject a product due to how it sounds out of the box, give it time to "break-in", was a widely recognized truism.  Today there are devices that have components that don't "break-in", but if any are in the audio path that do age over time, they will indeed affect the resulting produced sound.  Tube amps are right there smack in the middle of being affected by "break-in", and tubes continue to age and "break-down" to the point of "going bad".   And, "Safety First", especially with devices that can kill you, several ways.
> 
> ...


Thank you for this!  I'm going to check out that review in a bit.

I've already been tube-rolling it (see my sig).  Plenty of burn on time coming this weekend....


----------



## hmscott (Dec 30, 2021)

ColSaulTigh said:


> Thank you for this!  I'm going to check out that review in a bit.
> 
> I've already been tube-rolling it (see my sig).  Plenty of burn on time coming this weekend....


Cool, that's great 

With tubes there is no easy "A/B" testing, unless you have 2 units running - burned-in semi-equally - with tubes also through initial burn-in - with tubes you don't want to burn-in "too far", as it is a waste of their useful lives 

This could be a negative for discerning "subtle" differences between tubes, but for most comparisons the difference is immediately noticeable, even after a longer than immediate power down/swap/warm-up.

The difference between 12AU7 and 12AT7 in TA-20/TA-30 is great enough that it is immediately noticeable.  The 12AU7 is softer with less attack than 12AT7, at least the one's I've heard in the TA-20 - and I've heard the same reports from TA-30 owners.  The last TA-30 owner I talked with was overwhelmingly positive on E80CC tubes, a longer life (10,000 hours) 12AU7 variant.  I've found the E80CC sounds great in the TA-20 too.  Now, I am on to E180CC - a long life (10,000 hour) 12AT7 variant.

The TA-30 outputs 50% more power (3000mW) than the TA-20 (2000mW), but the TA-30 also has an internal DAC which I would pay for and not use as I already have an external Topping D90 DAC.   I have asked Xduoo if they would produce an updated TA-20 with TA-30++ power for power hungry Planars like the Hifiman HE6SE V2 and 600ohm headphones - and without a built-in DAC - then the pandemic hit, I'm not sure where Xduoo are with that product...

The TA-26 - tube only - has it's own unique advantages over the TA-20/TA-30, as I am discovering - I haven't even ordered tubes to roll yet 

At least for my Beyerdynamic 600ohm headphones, Hifiman Ananda's, quite likely my Sennheiser 150ohm/300ohm headphones, the TA-26 even on stock tubes has an engaging sound... and it is "only" $319, if you are looking for a "lark" the TA-26 is an inexpensive one with the only limitation I can see is 60ohm or less headphones/IEM's...


----------



## hmscott (Dec 30, 2021)

cirodts said:


> the 12AT7 and 12AX7 are not suitable for the TA-20 or am I wrong?
> I only use 12au7 for safety.





hmscott said:


> Xduoo has confirmed that the 12AT7 and 12AX7 were ok to use in the TA-20 before I tried it myself.  You could email service@xduoo.net to ask the same question so you can hear it direct from Xduoo.
> 
> December 14, 2020, relayed through Hifigo from Xduoo:
> "Hi Scott, sorry for late reply.
> ...


Here is another Tube design that accommodates a 12AU7, 12AT7, and 12AX7, and others... 

"_This design decision permits the circuit to operate many low, medium, and high gain tubes that are available today from current manufacturers. NOS tubes are also available and will provide the user with even more choices. You can use 12-AU7, 12-AT7, 12-AX7, and many more._"
"The Stealth will enable you to adjust your gain (volume) to your liking depending on the strength of your input signal. This will eliminate the need for a gain switch especially when an attenuator is being used. Thus the flexibility and strength of this amp will make you appreciate the variety and number of tubes that it can accommodate to tailor the sound to your liking."
http://www.raysamuelsaudio.com/products/stealth.html
Stealth Pre-Amp/Headphone Amp     $2,495.00

The Stealth is a much different headphone amp + pre-amp, and much more costly, it is impressive how Xduoo accomplished a similar wide compatibility with tubes for such a low price of $399 with the TA-20.


----------



## cirodts

what do the 12at7 and 12ax7 have better than the 12au7 on the TA-20?


----------



## PetFju

cirodts said:


> what do the 12at7 and 12ax7 have better than the 12au7 on the TA-20?


Like @hmscott mentioned above; the 12AT7 seems to offer a little more of everything so to speak, except "tube-muddiness". 
Only thing to keep in mind is that it is also more "immediate" and dynamic (in my opinion) in the TA-20, and as such as such can (to some people) make the amp sound more like solid state. 
My experience is that it opens up the soudstage a little, gives a little morer "oomph" where needed, and is just "better", as subjective as that may be. YMMV as far as type and quality of tube goes though, as i find the tung-sol 12AU7 black glass to be quite similar in sound to f.ex. the 12AT7 mullard that i have, except it sounds a little more "rounded", as in less etched highs (for better or worse).


----------



## hmscott (Dec 31, 2021)

cirodts said:


> what do the 12at7 and 12ax7 have better than the 12au7 on the TA-20?


The subjective increase in impact, soundstage, and overall enjoyment.  The same as finding better sounding (to you) 12AU7's, the 12AT7 opens up a wider range of options, and again I wouldn't suggest jumping in all at once, take your time with exploring the 12AU7 and 12AU7 variants first, to get a good ear to what to listen for as far as differences, before jumping off into 12AT7, E80CC, E180CC, 12BH7, etc.

That path provided me with months of listening enjoyment - getting to know the 12AU7 options, hunting them down, finding the best measuring and best priced 12AU7's, and then when I was ready  - I felt I could do justice to a whole new target when I found one, I moved to 12AT7's, and on to E80CC, 6060, and recently E180CC's.

And, for me the 12AX7 is a bit too *HOT* sounding in the TA-20, perhaps get a nice RCA 12AX7 Black Plate to try and see what I am talking about, but I wouldn't start off ordering a bunch of 12AX7s to start, I'd sample a single 12AX7 pair first. 


PetFju said:


> Like @hmscott mentioned above; the 12AT7 seems to offer a little more of everything so to speak, except "tube-muddiness".
> Only thing to keep in mind is that it is also more "immediate" and dynamic (in my opinion) in the TA-20, and as such as such can (to some people) make the amp sound more like solid state.
> My experience is that it opens up the soudstage a little, gives a little morer "oomph" where needed, and is just "better", as subjective as that may be. YMMV as far as type and quality of tube goes though, as i find the tung-sol 12AU7 black glass to be quite similar in sound to f.ex. the 12AT7 mullard that i have, except it sounds a little more "rounded", as in less etched highs (for better or worse).


Yup, that is also what I have found.  The dynamic impact of the 12AT7 is only exceeded by the E80CC (12AU7 variant) and now that I've experienced the E180CC (12AT7 variant) it has the characteristics of the 12AT7 in the TA-20, in an upgraded longer life tube design - 10,000 hours, and the E180CC delivers to my ears the best so far, again.

In comparison to the TA-26, even the most tubey sounding 12AT7/E180CC/6060/E80CC tubes in the TA-20 pale in comparison to the TA-26 stock tubes for tubiness.

But, the TA-20 with the 12AT7/E180CC/6060/E80CC tubes sound amazingly detailed - SS- like - in comparison to the broader deeper soundstage and tubiness of the TA-26.

I think both the TA-20 and TA-26 are making a wide dual path into the audio soundscape, both have different strengths and both best serve different headphone impedances best, I'm enjoying A/B'ing both side by side.


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## hmscott (Dec 31, 2021)

Happy New Year!!

I love these old Tube movies, this one is from 1940, years gone by, it is fun to look back at yesteryear when approaching a new year...and to see our NOS Tubes when they were brand new!

_*AT&T Archives: A Modern Aladdin's Lamp, about vacuum tubes,1940*_


*Vacuum Tubes/Valves by Mullard ~Manufacture for Audio TV Radio*


*Vintage Technology: Vacuum Tubes 1943 Training Film (The TRIODE) Signal Corps Army Air Force Radio*
​


----------



## PetFju

hmscott said:


> Happy New Year!!



Happy new year, to everyone here


----------



## cirodts

hmscott said:


> The subjective increase in impact, soundstage, and overall enjoyment.  The same as finding better sounding (to you) 12AU7's, the 12AT7 opens up a wider range of options, and again I wouldn't suggest jumping in all at once, take your time with exploring the 12AU7 and 12AU7 variants first, to get a good ear to what to listen for as far as differences, before jumping off into 12AT7, E80CC, E180CC, 12BH7, etc.
> 
> That path provided me with months of listening enjoyment - getting to know the 12AU7 options, hunting them down, finding the best measuring and best priced 12AU7's, and then when I was ready  - I felt I could do justice to a whole new target when I found one, I moved to 12AT7's, and on to E80CC, 6060, and recently E180CC's.
> 
> ...


between ta-20 and ta-26 which do you feel has the most impact for a rock metal listening?


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## hmscott (Jan 2, 2022)

cirodts said:


> between ta-20 and ta-26 which do you feel has the most impact for a rock metal listening?


It is going to depend the most on what impedance headphones you have.  If you have 60 ohm and under headphones then the TA-26 isn't a good match, literally 

The TA-20 does great on up through 300 ohm, and adequately at 600 ohm, but the TA-26 has a bit of an edge at 600 ohm, for any genre.

I don't listen to metal though, so I cannot give you any specific comparisons... perhaps someone else that is a fan of metal can help you?
PS @cirodts -  song/album links, youtube/Tidal or the full name of the song/title/band, I will compare them on the TA-20 and TA-26


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## hmscott (Jan 3, 2022)

Well, I went and did it, I ordered some new tubes for the TA-26:

I ordered some Russian 6ASG compatible tubes, those are gonna take 4-6 weeks to get here - he is on vacation till the 15th and then he said it takes 3 weeks to transit, and I listed them here in a For 6AS7G tube rollers here ..... group post where I researched them. These are the large Stepped Glass tube envelope tube in the back of the TA-26

Then I bought a few 6SN7's.  For 2 of them the dealer was kind enough to split 1 tube off of his Quad/Pair Matched Tube Listings!, what an accomodating dealer...

6SN7 GTA SYLVANIA NOS SAME DATE CODE TALL GLASS
TUBE1) 3000/3000 uSIEMENS ; 7.6/7.6 ma
https://www.ebay.com/itm/143395297531

SYLVANIA VT 231 6SN7 GT NOS Well-Balanced Gm ; Ip
TUBE1) 94/95 uSIEMENS ; 10.3/10.4 ma
https://www.ebay.com/itm/133347142184

And, the same goes for another 6NS7 split from a pair:

Sylvania VT-231 6SN7GT ECC33 Mil-Spec Tubes - Matched Pair, Tested, NOS, Bad Boy
These tubes have black Bad Boy T plates and foil getters. Date codes are from the late 1940's. The tubes test with readings of 110/110...
https://www.ebay.com/itm/255288806061

When I ask for a specific tube - with it's identifying measurements - I only purchase from dealers that list the full measurements - I ask for tubes "like this" (if I remember) instead of those specific tubes, but these dealers were very helpful right off, I'd not purchased from either of them before.

I'm used to purchasing pairs of tubes for the TA-20, this is new, needing to find only 1 of each tube type when everyone else seems to want pairs or quads of these tubes


----------



## cirodts

hmscott said:


> It is going to depend the most on what impedance headphones you have.  If you have 60 ohm and under headphones then the TA-26 isn't a good match, literally
> 
> The TA-20 does great on up through 300 ohm, and adequately at 600 ohm, but the TA-26 has a bit of an edge at 600 ohm, for any genre.
> 
> ...


thanks, that's why the dt 880 600 hom sounded better on the ta-26 than the ta-20, so a dt 880 250 hom will do well on the ta-20.


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## hmscott (Feb 27, 2022)

....


cirodts said:


> thanks, that's why the dt 880 600 hom sounded better on the ta-26 than the ta-20, so a dt 880 250 hom will do well on the ta-20.


Actually, a 250ohm headphone should do great on the TA-26, but I haven't tried my 120/250/300 ohm headphones on the TA-26 yet, I'm taking it slowly.

And, yes the TA-20 does a great job with 250 ohm headphones too


----------



## cirodts

I would like to buy a hifiman ananda to match the xduoo ta-20, is it a good match in your opinion for a rock listening?


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## hmscott (Jan 3, 2022)

cirodts said:


> I would like to buy a hifiman ananda to match the xduoo ta-20, is it a good match in your opinion for a rock listening?


I certainly enjoy the Ananda on the TA-20, and I listen to Rock, and I have really enjoyed it.  And, I listen to a wide range of music and enjoy it on the Ananda.

Moon-Audio thinks the Ananda is to be recommended for Rock and Metal, along with other Hifiman headphones:
https://www.moon-audio.com/best-headphones-for-rock-and-metal-

I was surprised to find Moon-Audio don't include the Ananda in other music categories, but instead recommend the more expensive Arya...

I have enjoyed listening to the Ananda on the TA-26 - even though the Ananda should be too low in impedance @ 25 ohm's - 33.2 ohm's measured.  Ananda is also very sensitive at 109.2 dB/V SPL - I think that plays into making the Ananda very listenable on the TA-26 which isn't recommended for headphones under 60 ohms.

Side by side I prefer listening to the Ananda on the TA-20, as on the TA-26 the Ananda doesn't get as loud as on the TA-20.

I would rather recommend Sennheiser headphones, or Beyerdynamic headphones with mid-range impedance because those lines of headphones were what I have listened to Rock on most of my life.

If you already have those headphones and want to experience something different, then I think the Ananda is a great choice


----------



## cirodts

the bayers and sennheisers did not please me much because they are not engaging, I much prefer the fidelio x2hr headphones which have a very strong impact on rock.
I remember ananda with topping a90 a very clean and wide sound but unfortunately it was not as full-bodied and full as I hoped, on the ta-20 you find the ananda a little warm and full?
thank you.


----------



## hmscott (Jan 4, 2022)

cirodts said:


> the bayers and sennheisers did not please me much because they are not engaging, I much prefer the fidelio x2hr headphones which have a very strong impact on rock.
> I remember ananda with topping a90 a very clean and wide sound but unfortunately it was not as full-bodied and full as I hoped, on the ta-20 you find the ananda a little warm and full?
> thank you.


Well, I wouldn't call the Ananda, "warm" and full, but I think "detailed" and engaging would be fair. 

There are no perfect headphones that I have ever heard, only more open and engaging, and the Ananda is a definate upgrade for me.

The Hifiman Sundara or the new Hifiman Edition Xs might be another good choice, I haven't heard them but the reports I've heard are good.

I've also heard the Arya are a good uprade to the Ananda, as is of course is the Susvara.

The Ananda also has that long tall fitting oddity.  I am 6'2", and have a  large / tall head, so for me the Ananda fits perfectly and is very comfortable for many hours of enjoyable listening, but others have said the Ananda is a bit too big for them.

The Sundara might be a good choice if the Ananda isn't a good fit, as the Xs and Susvara are also best fitting for a long / tall head.

For me the Ananda is a good fit, and a nice upgrade, and along with the HE6SE V2 have been very enjoyable on the TA-20.

I also enjoy the new HD660s on the TA-20, and I really like the long time Sennheiser and Beyerdynamic sound - I also enjoyed the new Beyerdynamic Amiron Copper Wireless, so maybe my favorite headphones won't match yours?

It is all very personal, and I think very dependent on what equipment we use to drive them, as well as what music we enjoy listening to, many many variables go into whether a headphone will "click" or not...all we can do is listen and enjoy the uniqueness of each headphone.


----------



## No Deal

I am thinking about pairing this amp with the Audio Technica WP900 (38 ohms) for my work desktop.  Foolishness or possible? I am not certain about whether or not this amp sounds as good close to 8 ohms as it does several hundred ohms.


----------



## hmscott (Jan 5, 2022)

No Deal said:


> I am thinking about pairing this amp with the Audio Technica WP900 (38 ohms) for my work desktop.  Foolishness or possible? I am not certain about whether or not this amp sounds as good close to 8 ohms as it does several hundred ohms.


If you are thinking of the Xduoo TA-20 then yes it is a good match, as the TA-20 supports 8ohm to 600ohm.  And, the WP900's 100 dB/mW sensitivity should help too.

The Xduoo TA-26 is a tube only AMP and the design supports 60 ohms to 600 ohms, so it would not be a good fit - theoretically - with a 38 ohm headphone, but here I am enjoying the sound of the TA-26 on my 25-33 ohm Ananda's, where Hifiman's listed 103 dB/mW sensitivity helps it perform well on the TA-26.

So IDK what to say, by specs the TA-26 wouldn't work, but it will likely depend on the headphone - and how it interacts with the TA-26 in real life.

Also the TA-26 handles 600 ohm with more punch than the TA-20, even though both list 600 ohm support.

With the TA-20 I can run the full output of my Topping D90 4v XLR into the TA-20 with all of my headphones, Xduoo lists maximum input voltage as 8v, but the TA-26 Volume control seems a bit over sensitive in that it has a very small volume "range" on the dial if I run the full RCA input from the D90.  Especially with my Sennheiser 660s, it helps to attenuate the D90 output from -12dB to -20dB to get more travel on the TA-26 volume control.
I hope you were talking to me, asking about the TA-20/TA-26


----------



## hmscott (Jan 6, 2022)

cirodts said:


> between ta-20 and ta-26 which do you feel has the most impact for a rock metal listening?


Ok, so I found some "Metal", and there seems to be a lot of "*SHOUTING!!"*. 

*Best of Metal 2021 - Tidal*
https://tidal.com/browse/playlist/2af6731f-36e0-4f01-acbb-415252aa35f1

And, for the TA-26, I swapped in one of the new tubes - a 6N8P replacement, the Sylvania VT-231 6SN7GT (Late 1940's) measuring 110%/110% Lifetime, and "Wow!", that made a huge improvement!

My first thought was, that really added some "impact", and that reminded me of your question, find Metal, and...

Now the TA-26 is solidly rocking Metal!  The Guitar licks, and Growling, are winning me over... 

Now it is an even tougher call.  The TA-20, using Mullard E180CC NOS tubes, was in the lead with more detail and impact, and now the TA-26, using the Sylvania VT-231,  has added impact + detail and lost the "sharp edges" that were due to the stock tube.

The "G.E. 6AS7GA" replacement for the stock 6N5P is arriving in a few days, hopefully that will kick things up another notch


----------



## No Deal

hmscott said:


> If you are thinking of the Xduoo TA-20 then yes it is a good match, as the TA-20 supports 8ohm to 600ohm.  And, the WP900's 100 dB/mW sensitivity should help too.
> 
> The Xduoo TA-26 is a tube only AMP and the design supports 60 ohms to 600 ohms, so it would not be a good fit - theoretically - with a 38 ohm headphone, but here I am enjoying the sound of the TA-26 on my 25-33 ohm Ananda's, where Hifiman's listed 103 dB/mW sensitivity helps it perform well on the TA-26.
> 
> ...


Yes.  The TA-20 is what I would like to try. I plan to connect it to my Ibasso DX160's line out and hope for the best.  Thank you!


----------



## vmiguel

Joining the club


----------



## kibot

Privet!
Can sombody help -  I use TA-26 with Cambridge Audio DacmagicPlus DAC and Takstar HF580 headphones with my PC as a sourse – so i hear sound distortions in high-mid and especially in high volume. Is this normal for such setup? (also i use ibasso dx 80 as a sourse and there are no sound distortions)


----------



## ColSaulTigh

kibot said:


> Privet!
> Can sombody help -  I use TA-26 with Cambridge Audio DacmagicPlus DAC and Takstar HF580 headphones with my PC as a sourse – so i hear sound distortions in high-mid and especially in high volume. Is this normal for such setup? (also i use ibasso dx 80 as a sourse and there are no sound distortions)


How works you describe the "distortion"?  Is it crackly, fuzzy, garbled, clipped?


----------



## vmiguel

I have a TA-26 with Cambridge DacMagic 200M and Senn HD 650 (Drop version) and no distortion. Tube amps are normaly regarded as a not so good match with low impedance phones, and specially with planar. Do you have any dynamic driver phones to test? Or a higher impedance ones?


----------



## kibot

ColSaulTigh said:


> How works you describe the "distortion"?  Is it crackly, fuzzy, garbled, clipped?


Clipped 



vmiguel said:


> I have a TA-26 with Cambridge DacMagic 200M and Senn HD 650 (Drop version) and no distortion. Tube amps are normaly regarded as a not so good match with low impedance phones, and specially with planar. Do you have any dynamic driver phones to test? Or a higher impedance ones?


Only "kz dq6" - i will try it tommorow 

So as i said - i almost dont hear those distrotion (clipped ) when i use ibasso dx 80 as a sourse(only in very high volume)


----------



## vmiguel

Those KZ are IEM with even lower impedance...
In my case I've found that the output from the DacMagic was too high, limiting the volume travel on the TA-26. It was too loud even bellow 9 o'clock position. But the DacMagic has a preamp mode wich allows to lower the volume on the dac, so you can get more travel on the TA-26. Maybe you can try this?


----------



## kibot

vmiguel said:


> Those KZ are IEM with even lower impedance...
> In my case I've found that the output from the DacMagic was too high, limiting the volume travel on the TA-26. It was too loud even bellow 9 o'clock position. But the DacMagic has a preamp mode wich allows to lower the volume on the dac, so you can get more travel on the TA-26. Maybe you can try this?


Great spasibo for anwer !🙋‍♂️
Im not at home now - i will try it tommorow
So i need to use volume knob in DacMagic(now it switch off and i use only TA 26 volume knob) - right?


----------



## vmiguel (Jan 7, 2022)

Look at the DacMagic manual. The volume has two modes for the RCA/XLR connections: fixed (the volume does nothing and the DAC is always on max), and preamp mode (the volume works as expected).
The DacMagic volume always works for the heaphone out, the modes I'm mentioning only affect the RCA/XLR out in the back.
So, on preamp mode you turn down the volume on the dac and see (hear) if the distortion goes away. Naturaly, to get the same volume on the Takstar you will need to turn up on the TA-26.

EDIT: From the manual:



> Note: The DacMagic Plus is supplied as default with Digital Preamp mode enabled. In this mode the output from the Unbalanced and Balanced audio outputs is controlled by the front panel Volume control. If you wish to disable this mode (and have fixed line-level level output from the Unbalanaced and Balanced Audio outputs) switch the DacMagic Plus off, then push and hold the Volume control in whilst switching the DacMagic Plus on. The DacMagic Plus confirms the setting by flashing the source LEDs downwards for Digital Preamp Mode and upwards for Fixed Line Level Mode.


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## kibot (Jan 8, 2022)

vmiguel said:


> Look at the DacMagic manual. The volume has two modes for the RCA/XLR connections: fixed (the volume does nothing and the DAC is always on max), and preamp mode (the volume works as expected).
> The DacMagic volume always works for the heaphone out, the modes I'm mentioning only affect the RCA/XLR out in the back.
> So, on preamp mode you turn down the volume on the dac and see (hear) if the distortion goes away. Naturaly, to get the same volume on the Takstar you will need to turn up on the TA-26.
> 
> EDIT: From the manual:


Hello! So i tried this and thats sounds better now but the distortion(clipped) appear in high\very high volume in loud-recorded songs.
So how and on what should I adjust the volume now ? (for example I use TA-26 volum knob in 12 or 2 o'clock lever now(its between mid and high-mid voume)


----------



## PetFju (Jan 8, 2022)

kibot said:


> Hello! So i tried this and thats sounds better now but the distortion(clipped) appear in high\very high volume in loud-recorded songs.
> So how and on what should I adjust the volume now ? (for example I use TA-26 volum knob in 12 or 2 o'clock lever now(its between mid and high-mid voume)



Hi

My view on this might not be what you want for an answer, and it's not a direct answer to you question. However; i truly believe it will be the best solution for you if it is an option.
If i were you i'd immedeately sell or in another way swap out the dacmagic + . 

Let me explain my standpoint here; When i first started my true HiFi journey, my first real Dac was the Dacmagic + from Cambridge audio. At first i was happy, but as i kept listening i realized i was having issues with fatigue because of a high-mid emphasis, and a treble spike. I went as far as to change just about all of my components out to try and fix this issue, but i eventually realized that the reason for the issue was the dac. And i who thought all dacs sounded good because all it did was translate 1's and 0's..

Anyways, my problem all along was the Dacmagic +, and once i realized this and started researching dacs and options i not only found myself enjoying my stereo, but learned that i was not alone in this opinion on the dacmagic+. 
Reasons why the dacmagic+ sounds this way are from what i learned two-fold; 
1. The dac chip. The particular chip (Wolfson WM8740) lends itself to this kind of "sharp" sound (for reasons unknown to me). 
2. The power supply. The wall-wort that comes with the dacmagic+ does the dac no favors. 

The problem could get better or even close to remedied with a linear psu, but that costs about as much as a new dac. 
To summarize; if you could afford it i would highly recommend getting a new dac. It would solve your issues, as well as give you a better sound experience, IMHO. 

Lastly; this is my subjective opinion on the matter, and for all i know you love the sound of the dacmagic+. If that's the case just disregard this post, in the end this is all about what makes you happy .


----------



## kibot

PetFju said:


> Hi
> 
> My view on this might not be what you want for an answer, and it's not a direct answer to you question. However; i truly believe it will be the best solution for you if it is an option.
> If i were you i'd immedeately sell or in another way swap out the dacmagic + .
> ...


Great thanks for opinion and advice - so i aslo use it as preamp to my Audionet APM 3 + Polk Audio S20 and i like the sound 

...but i agree - i will sell it in future but now i need to use it


----------



## kibot

So i also want to ask about TA 26- is that transformer noise are normal for this model? (there is not from tubes cuz the noise are here without tubes but in 50% quiter)


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## PetFju (Jan 8, 2022)

kibot said:


> So i also want to ask about TA 26- is that transformer noise are normal for this model? (there is not from tubes cuz the noise are here without tubes but in 50% quiter)



That sound is not supposed to be there, meaning not at all that strong anyways. It's kind of hard to tell, but could it be a 50 or 60hz noise? I don't know what kind of power grid you have where you live (Russia?), but it could be "transformer-hum" if it's in the frequency of the powergrid. 
There could be all kinds of reasons why that happens, it could be different harmonic intereference from the power grid, or it could be that the transformer is loose inside its case or hase loose windings, if this is indeed the issue.

Or it could also be faulty tubes, i have had a music angel ma800 (i think it was) with a faulty KT88 tube which sounded similar. 

But to me it does sound like a power-related issue.

Btw; nice guitar


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## kibot (Jan 8, 2022)

That's what official xduoo servise answer after i check the amp without tubes :
 "So,we can confirm that the noise is comming from the tranformet. But if the noise is not bother your listening,you can continue to use it or you can return it to us for free repairing"
So that noice dont bother my listening and i just wanted ask users about it

Offtop - spasibo! i have a collection of this guitars . This guy make it with hellyeah awesome quality https://lavky.com/mg-custom-shop/


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## hmscott (Feb 27, 2022)

kibot said:


> Privet!
> Can sombody help -  I use TA-26 with Cambridge Audio DacmagicPlus DAC and Takstar HF580 headphones with my PC as a sourse – so i hear sound distortions in high-mid and especially in high volume. Is this normal for such setup? (also i use ibasso dx 80 as a sourse and there are no sound distortions)





vmiguel said:


> I have a TA-26 with Cambridge DacMagic 200M and Senn HD 650 (Drop version) and no distortion. Tube amps are normaly regarded as a not so good match with low impedance phones, and specially with planar. Do you have any dynamic driver phones to test? Or a higher impedance ones?





kibot said:


> Clipped
> 
> Only "kz dq6" - i will try it tommorow
> 
> So as i said - i almost dont hear those distrotion (clipped ) when i use ibasso dx 80 as a sourse(only in very high volume)





vmiguel said:


> Those KZ are IEM with even lower impedance...
> In my case I've found that the output from the DacMagic was too high, limiting the volume travel on the TA-26. It was too loud even bellow 9 o'clock position. But the DacMagic has a preamp mode wich allows to lower the volume on the dac, so you can get more travel on the TA-26. Maybe you can try this?





kibot said:


> Hello! So i tried this and thats sounds better now but the distortion(clipped) appear in high\very high volume in loud-recorded songs.
> So how and on what should I adjust the volume now ? (for example I use TA-26 volum knob in 12 or 2 o'clock lever now(its between mid and high-mid voume)


*Note: the TA-26 only supports headphones with impedance from 60 ohm to 600 ohm - Low impedance headphones and low impedance IEM's aren't a good fit for the TA-26.*

The TA-26 has a fixed gain with a very narrow volume dial range depending on what impedance/sensitivity headphones are used.  Beyond the top of that narrow volume range the TA-26 gain is too high and can be overdriven by the DAC input.  In use the TA-26 can have way too much gain and no gain switch, attenuating the output of the DAC at the DAC, or with a Passive/Active Preamp between the Fixed output DAC and the TA-26 could help tame the gain.

The TA-20 doesn't have a gain switch either, but the TA-20's design works without the need for a gain switch, up to 8vpp input on XLR.  I can use my D90 in DAC mode at full output, and not worry about varying the output voltage.

For the TA-26 I set the D90 Preamp output from -12dB to -20dB attenuation depending on the headphones - with adequate attenuation the TA-26 volume dial is much nicer to adjust the volume, with a broader space to use on the volume dial, I like to have from 9 o'clock to a bit past 12 o'clock.  After setting the DAC output level for a specific impedance headphones, I only adjust the TA-26 volume control.

Right now I am listening with the Sennheiser 660S 120ohm @ -20dB D90 output.  With higher impedance headphones I don't need to reduce the D90 output to the TA-26, such as my Beyerdynamic DT880/DT990 600 ohm headphones.

*Note: the TA-26 only supports headphones with impedance from 60 ohm to 600 ohm - Low impedance headphones and low impedance IEM's aren't a good fit for the TA-26.*


kibot said:


> So i also want to ask about TA 26- is that transformer noise are normal for this model? (there is not from tubes cuz the noise are here without tubes but in 50% quiter)


I'd ask Xduoo if they would cross-ship a TA-26 model for your region, to minimize your downtime without a TA-26, otherwise I'd ship it to Xduoo for a transformer/parts swap.

IDK the long term effect of running with the wrong hz/cycle mismatch, but to me that mechanical noise is way too loud to deal with, I'd get it fixed / replaced.

There could be some relation between some of the distortion you are hearing and the power hz/cycle mismatch causing mechanical vibration.  That mismatch could be showing up as unattenuated normal hz/cycle distortions - IDK what parts changes are involved in localizing for your region/power.

It could also be a bad transformer/parts, either way a replacement swap or a RMA is needed to get rid of that transformer buzz.


----------



## kibot

hmscott said:


> *Note: the TA-26 only supports headphones with impedance from 60 ohm to 600 ohm - Low impedance headphones and low impedance IEM's aren't a good fit for the TA-26.*
> 
> The TA-26 has a fixed gain with a very narrow volume dial range depending on what impedance/sensitivity headphones are used.  Beyond the top of that narrow volume range the TA-26 gain is too high and can be overdriven by the DAC input.  The TA-26 has too much gain and no gain switch.
> 
> ...


Great thanks for answer!!!!🙋‍♂️
So how i can set the attenuation from -12 to -20 dB ? DacMagic unfortunately havent any volume indication😔

About ta26 external noise - it also may be cuz of electricity grid in my apartament(there are only external noise not in headphones)


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## hmscott (Jan 8, 2022)

kibot said:


> Great thanks for answer!!!!🙋‍♂️
> So how i can set the attenuation from -12 to -20 dB ? DacMagic unfortunately havent any volume indication😔


Using some trial/error you can find the optimal setting of the DacMagic attenuation for each headphone.  I like to have a 9 o'clock to just over 12 o'clock span on the TA-26 volume dial, and a -12dB to -20dB setting on the D90 allows that volume range on the TA-26, with the headphones I've tried, so far.  You could make a back drop of Marks behind the DacMagic "Volume" dial where each headphone you have allows the range on the TA-26 volume dial you enjoy.


kibot said:


> About ta26 external noise - it also may be cuz of electricity grid in my apartament(there are only external noise not in headphones)


Yes, it could be a bad power grid causing the HZ/cycle mismatch.  I have seen very dirty power requiring a large "isolation transformer".  When I lived near a lake in the wilds of Yosemite, the Mountain Power killed my Macintosh within about 30 minutes, the 2nd Macintosh power supply bit the dust after only a few minutes.  A giant 75lb isolation transformer was enough to smooth out the power spikes until the power company could replace line equipment that was causing the problem.

A HZ/Cycle mismatch is tougher to compensate, you would need a conditioning power supply that can also recover/adjust/smooth the output to the correct power cycle. Probably too expensive new, but perhaps some surplus Russian Military hardware can be found?

You could get an inexpensive power socket tester, to make sure it is wired correctly coming from the wall socket/power strip.

Also, I wanted to mention that the TA-26 stock tubes are "crunchier" at the limits, compared to the upgraded tubes I am breaking in now.  And, these new tubes are getting sweeter by the day, as they break-in.  I've read 50-100 hours, 200 hours at the outside for some 10,000 hour rated tubes, is enough to sweeten the sound.

Russian OTK Military 6SN7/6AS7G tubes are reported to sound great, and are competitive with the much more expensive NOS US tubes for much lower cost.  My Russian tube order is shipping on Jan 15th, so I'll report back after they've arrived and been broken in.


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## kibot (Jan 8, 2022)

hmscott said:


> Doing some trial/error you can find the optimal setting of the DacMagic attenuation.  My goal is to be able to use 9 o'clock to just over 12 o'clock on the TA-26 volume dial, and a -20dB setting on the D90 allows that volume range on the TA-26.
> 
> Yes, it could be a bad power grid causing the HZ/cycle mismatch.  I have seen very dirty power requiring a large "isolation transformer".  When I lived near a lake in the wilds of Yosemite, the Mountain Power killed my Macintosh within about 30 minutes, the 2nd Macintosh power supply bit the dust after only a few minutes.  A giant 75lb isolation transformer was enough to smooth out the power spikes until the power company could replace line equipment that was causing the problem.
> 
> ...


Ah i forgot to say - extarnal noise appears durin 5-7 minutes after i switch it on


And also i noticed that distirtion (clipping)of sound appears in loud-recorded music , there are many songs where i can use almoust 100% of volume without distortions (clipping)🤷‍♀️


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## ocZZ (Jan 10, 2022)

I wanted to share some experiences since getting the TA-20 about a month ago.  I'm running balanced from a Topping D10b and this combo sounds much better than the  Topping E30 / Drop THX Amp before it.   I've tried a few different tubes based on recommendations in this forum:

(edited)
# *stock */ I only tried for a few days and sounded OK.
#* JJ ECC802s/12AU7*  /  improvement from stock, larger soundstage, highs more rounded.
# NOS *Radiotechnique/RT 12AT7WA/ECC81 *France O-Getter / meh.  Very detailed to the point that it's fatiguing.
# Upscale Audio NOS RAF *Mullard CV4024 12AT7 / *These were my favorite before getting the E180CC's below.  Very good but not on the same level of the Amperex.
# NOS *AMPEREX *HOLLAND 1960'S* E180CC *7062 D-getter / These are the best I've tried so far.   I'm thinking of checking out some other E180CC's since these were so good.

Maybe the best change from stock has been replacing the stock USB cord going to my DAC with another cable.  The Topping D10b taking audio and power from the USB and I replaced it with a Oyaide NEO d+ class A USB cable *and *iFi iSilencer+.  The iFi iSilencer made a small difference *I think* but changing the cable from stock to the Oyaide NEO was a wow moment.  I'm thinking of replacing balanced interconnects with Oyaide next.  Anyways, I'm really enjoying the amp and thank you everyone for the recommendations in this thread.
​
​


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## hmscott (Jan 10, 2022)

ocZZ said:


> I wanted to share some experiences since getting the TA-20 about a month ago.  I'm running balanced from a Topping D10b and this combo sounds much better than the  Topping E30 / Drop THX Amp before it.   I've tried a few different tubes based on recommendations in this forum:
> 
> # *stock */ I only tried for a few days and sounded OK.
> #* JJ ECC802s/12AU7*  /  improvement from stock, larger soundstage, highs more rounded.
> ...


I found the same small incremental change by adding the iFi iSilencer+, the biggest reduction in PC induced noise (GPU) was the iFi iDefender+, but if you don't have GPU induced "chirping" from the PC source, then it's not absolutely necessary, but might be worth a try, because sometimes we don't know what noise level we are hearing until it is gone.

Most PC USB sources are going to carry noise on the 5v power lines in the USB cable, so as long as your DAC doesn't need that power to function, you can disconnect it, and the iFi iDefender on of the easiest ways to accomplish that disconnect.

I've had the same listening results for the tubes like yours I've heard on the TA-20, all great choices at their price points.  Someone could go for a long time with only the JJ ECC802S Gold pin, and they aren't expensive at all; it is the 17mm long plates and the rugged construction that makes 12AU7's sound great and exhibit low noise.

For me the Mullard 12AT7 are "end game", even more so the Mullard E180CC, which is what my TA-20 has installed, right now. Along with pretty much any Holland Heerlen factory made tubes, and if you can find Holland Heerlen Mullards, especially E180CC's, those are the "best", along with the British made Mullards in Mitcham and Blackburn.

What tubes are you planning on trying next?


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## ocZZ (Jan 8, 2022)

I've spent just about as much on tubes as the amp itself at this point  also, just retesting the 12AT7 Mullards and E180CC Amperex with the new USB cable, it's clear the Amperex is a better fit. The highs are more rounded (can be too bright on Mullard), the mids are more forward (mids muted and muffled on Mullard), bass is about the same but maybe abit tighter on Mullard but sound stage is really good on the Amperex. I think these are from Harleen according to the item description but not Mullard but Amperex. https://www.ebay.com/itm/185071855549


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## hmscott (Jan 15, 2022)

ocZZ said:


> I've spent just about as much on tubes as the amp itself at this point  also, just retesting the 12AT7 Mullards and E180CC Amperex with the new USB cable, it's clear the Amperex is a better fit. The highs are more rounded (can be too bright on Mullard), the mids are more forward (mids muted and muffled on Mullard), bass is about the same but maybe abit tighter on Mullard but sound stage is really good on the Amperex. I think these are from Harleen according to the item description but not Mullard but Amperex. https://www.ebay.com/itm/185071855549


That is the dark secret behind Tube amplifiers, the cost of the "razer" isn't anywhere near the cost of the "Blades", over time. That is why it is important to shop around, learn the details about each tube before buying.  Often a little patience, waiting for a good deal, pays off.  But, knowing when to pounce on a great tube at a great price can only be known through learning the details.

Yes, Amperex/Philips tubes from Holland Heerlen are great too.  And, pauls994 is a great guy to work with!

I forgot to mention, my first thought about your negative or less positive comments about some of the tubes, is that it takes 50-200 hours of run time for tubes to "mellow", the sharpness and recessed mid's disappear with burn-in.  At least that is what I've heard, when I can manage to leave in a set of tubes long enough.  Some explain it by the "burning off" of oxidized cathode material, when that has been burned through the sound improves.

I've found used tubes, with plenty of "meat" left on the bone, 95%/95% Lifetime, actually sound better than new tubes, they've already gone through burn-in.  But, then they HISS in my IEM's immediately or after a short while, so even 95% usage is too much, it is best to start with New/NIB NOS tubes, like these:

NOS NIB D GETTER PHILIPS/AMPEREX HOLLAND 1960'S E180CC 7062 TUBE 12AT7 TYPE

And, it may be that Mullards made in the Heerlen Holland plant are better sounding than those made in the British Mitchem / Blackburn tubes, but I've heard both and enjoy them greatly, I've not heard anything that would cause me to reject them.


----------



## Shared

Any tube rolling recomendations? I currently use my mt 602 w ge 5654w, looking for the most tubish sound


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## ocZZ (Jan 8, 2022)

Except for the stock pair and the Amperex holland E180CC's I just received; I've left the ta-20 on for a week while testing a particular tube pairing for burn in.  With the Amperex, I don't think that much time is needed  they're clearly better than all of the others.  The Amperex Hollands have completely different sound and really more aligned with what I was expecting when I got this amp.   Everything is tighter, the highs are controlled (without EQ), soundstage larger and just has an overall more pleasant sound.


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## PetFju (Jan 9, 2022)

So after y'all ranting on about the E180CC tubes i decided to take the plunge as well; https://www.ebay.com/itm/133642391945?hash=item1f1db51189:g:9qwAAOSwiftgBwl0
Will be interesting to see how the "SQ" tubes sound, as i've read many places that they're special (more than in name). 

Also, about USB cables..Not to start a debate here, because i just wont, but i've heard differences as well in both the USB cables and with galvanic isolators on the line for USB. I've used the Ifi ipurifier myself, but find that it adds some "glare" in the top end, which sounds unnatural. *EDIT: i should point out; it's the ipurifier V1, so that all might be better with the newer versions.

I bought the Topping HS01 to clean up some of the ground related noise, and i percieve it to do its job with zero audible negatives. Only problem is that you need two USB cables, as it needs an in and an out. 

Anyways; about the Oyaide cables; They are premium cables over all. Every cable i've had from there has been good. As a matter of fact i am using one of the right now into my HS01. 
But if anyone is out looking for a good, no-nonsense USB cable that is affordable, well shielded and makes the "sound" come out the other end as clean as it came in i can recommend Supra cables USB. They look cheap, but there's nothing cheap about their quality


----------



## PetFju

Oh by the way, and this goes out particularly to @hmscott; You guys are killing me with your TA-26 impressions as well, and it being lot more "tubey" than the TA-20. 
So now i've ordered one..

I foretell bigger tube expenses in my future as well now..lol


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## hmscott (Jan 15, 2022)

ocZZ said:


> Except for the stock pair and the Amperex holland E180CC's I just received; I've left the ta-20 on for a week while testing a particular tube pairing for burn in.  With the Amperex, I don't think that much time is needed  they're clearly better than all of the others.  The Amperex Hollands have completely different sound and really more aligned with what I was expecting when I got this amp.   Everything is tighter, the highs are controlled (without EQ), soundstage larger and just has an overall more pleasant sound.


That's great to hear, it is easy to be fascinated with the sound of a new tube before it has turned only to find it isn't sounding long term as you thought it did at first.

What are the rest of your listening system components and headphones?


PetFju said:


> So after y'all ranting on about the E180CC tubes i decided to take the plunge as well; https://www.ebay.com/itm/133642391945?hash=item1f1db51189:g:9qwAAOSwiftgBwl0
> Will be interesting to see how the "SQ" tubes sound, as i've read many places that they're special (more than in name)...


Both of your excellent E180CC finds have been in my eBay cart for a long time, but there are only so many tubes one can buy at a time before getting tube overload, which I've also done with the TA-20. 

Which is why it is so wonderful that we can all share our finds and compare them to other shared finds to help us all focus on our next purchases.  I had trimmed down my eBay cart to less than 50 after ordering the E180CC, I figured I was done for a while, then Xduoo drops the TA-26, and I am back up to 89 items in my eBay cart!

I'll fit in both E180CC's over the next 2 months and report my comparisons here too 


PetFju said:


> Oh by the way, and this goes out particularly to @hmscott; You guys are killing me with your TA-26 impressions as well, and it being lot more "tubey" than the TA-20.
> So now i've ordered one..
> 
> I foretell bigger tube expenses in my future as well now..lol


Congratulations on your new TA-26!!  

Here is what I've bought and received so far for the TA-26, which are already teaching me about the different variations of the 6N5P (6AS7G, 6080, 5998, 7632...) and 6N8P (6SN7 GT/GTA/GTB...) that come with our TA-26's:

Sylvania 6SN7GTA received 1/9, Cost $81.19
6SN7 GTA SYLVANIA NOS SAME DATE CODE TALL GLASS
TUBE1) 3000/3000 uSIEMENS & 7.6/7.6 ma
https://www.ebay.com/itm/143395297531

SYLVANIA VT 231 6SN7 GT NOS Well-Balanced Gm & Ip received 1/9, Cost $137.37
TUBE1) 94/95 uSIEMENS & 10.3/10.4 ma
https://www.ebay.com/itm/133347142184

Sylvania VT-231 6SN7GT ECC33 Mil-Spec Tube - Tested, NOS, Bad Boy, Single Tube received 1/5, Cost $100
This tube has black Bad Boy T plates and foil getters. Date code is from the late 1940's.  This was tested on my Dan Nelson calibrated TV-7B. It has been tested for shorts, gas, and transconductance. The tube tests with a reading of 110/110. Minimum is 50.
https://www.ebay.com/itm/255309286381

NEW BOXED MILITARY QUALITY G.E. 6AS7GA DUO-TRIODES FOR AUDIO received 1/6 Cost $42.54
BRAND NEW IN THE ORIGINAL CARTON ROUND GETTER SILVER TOP 6AS7GA POWER DUO-TRIODES MANUFACTURED BY GENERAL ELECTRIC FOR THE US MILITARY - ORIGINALLY USED AS A REGULATOR, THEY HAVE FOUND WIDE APPLICATION FOR AUDIO AMPLIFIER AND PREAMPLIFIER USE  Tested on my recently calibrated TV-7D/U where 36 is minimum tube measured 98/104.
https://www.ebay.com/itm/154779730790

The TA-26 China 6N8P - US 6AS7G - Russian 6H13C or 6N13S Svetlana tubes are much less expensive, and I've heard can be very quiet and good sounding, but not great - I'm not sure what that means yet, mine are shipping on the 15th and in shipping for 3 more weeks after that...there are also Russian 6SN7 equivalents, and I am to be getting one (or two, or more?) instead of a $17 refund on combined shipping, so I'll compare those too.

But, it's clear a lot of money can be spent on the TA-26 tubes, but with careful shopping I was able to get those bargains above, yes those tubes can sell for more, so I watch for the measurements - ask for the test results if not listed, but I've found over time if a seller doesn't list the measurements they probably can't provide them.  Many "from the case" sellers won't or can't test, and assume New In Box / NOS from case are as good as new.  Same as for the TA-20 tubes, with the TA-26 tubes I'm buying NIB or 100%/100% measuring NOS tubes.

The TA-26 sound is different than the TA-20, very enjoyable too but unique, and the stock tubes while nice and tubey can be "sharp" at the edges - as soon as I swapped in the first 6SN7GT VT-231 (late 40's) tube, the "sharp edges" were mostly gone, after installing the GE 6AS7G the "sharp edges" were gone.

I've since tried the other VT-231 6SN7GT and found they are of course very similar sounding, which made the Sylvania 6SN7GTA Tallboy Chrome Dome stand out as so differnt sounding.

The 6SN7GT, GTA, and GTB variants have differeces in their specifications - with the GT to GTA jump the largest - but I need to put in more reading time before I can say exactly what all those differences are.  The maximum plate voltage is the big one, I've learned that, but I've also learned that our Audio application doesn't "tax" these tubes, so even though the maximum Plate voltages are different between the GT and GTA/GTB we don't need to worry about that with the TA-26 - I need to confirm that with Xduoo, but first more reading, and listening!

BTW, the GE 6AS7G is in a smaller glass envelope, with straight sides instead of the billowing stepped glass of the stock 6N5P.  And, the GE 6AS7G is much smaller than the traditional stepped envelope, but it runs at about the same temperature of 143F.  The GE 6AS7G still "towers" over the 6SN7GT, but when I put in the Sylvania 6SN7GTA Tallboy Chrome Dome - the GE 6AS7G is now smaller than the tube in front!

The RCA 6AS7G is the "standard" and should be a first purchase, but I couldn't find any not overpriced when I was shopping for my first TA-26 tubes, so I went the Russian tube route.  I've since negociated splitting some Quad/Pairs for purchase next month.  Be sure an look for and ask for 5250/5250 mhos as a minimum target for your RCA 6AS7G, as the 100%/100% 5800/5800's are not to be found, althought I am going to keep looking 

When you get your TA-26, be sure to be aware that with full DAC output some headphones will have a very small usable Volume range - between 8-9 o'clock, turning down the DAC output with onboard attenuation if you have a Pre-mode, or through a Pre-amplifier to control the input to the TA-26, and now I have 9 o'clock to 1-3 o'clock on the TA-26 Volume dial.  I wonder if a different resistance value and curve on the TA-26 volume control would help?


----------



## ocZZ (Jan 10, 2022)

I'm at around 100 hours now with the Amperex Holland E180CC's and they just keep getting better  they also run warmer than the other tubes I've tried.   My setup is a Topping D10s > xDuoo TA20 > Hifiman Edition XS (balanced).  Any recommendations on another set of EC180's I could try?


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## hmscott (Jan 11, 2022)

ocZZ said:


> I'm at around 100 hours now with the Amperex Holland E180CC's and they just keep getting better  they also run warmer than the other tubes I've tried.   My setup is a Topping D10s > xDuoo TA20 > Hifiman Edition XS (balanced).  Any recommendations on another set of EC180's I could try?


There's Philips branding, made in Holland, same plant - IDK if the Philips is a rebrand of the Amperex - or the other way around.  The E180CC tubes from pauls994/Upscale audio are rebrands - CEC didn't make them - and there are lots of similar rebrands of Heerleen tubes by other brands too.

There are Philips SQ versions of most tubes Philips makes, which are selected for lowest noise / non-microphonic, basically cherry picked tubes.

There are the usually far more expensive "pinched waist" versions, earliest versions with "pinched" glass envelops to help secure the mica layers in place.  The expensive ones are non-microphonic, as they are typically microphonic.  A problem that can be minimized easily - ignore the external vibration induced noises, as long as the tube isn't self-resonating.

The E180CC is also called a 7062, and there may be specific medical, laboratory, aviation, space related culls of tubes of either kind.  Overtime I've seen various E180CC/7062's on eBay and eBay.uk.co and eBay.de, there are other tube sites around that likely have interesting variations.

The E180CC's from pauls994 right now are also sold by Upscale Audio, and they have various tubes of interest from time to time.

Brent Jesse sells tubes, and here is his 12AT7 listings page which includes E180CC tubes. tubemaze on eBay also has/had E180CC's, but I cannot see them right now as his store is closed till Feb 02.

And, speaking of great tall tubes, the E80CC also sound great, but run a bit hotter than the E180CC, a different sound - 12AU7 on "10,000 hour" heaters too, and sound great.

Please keep us up on what you find, with links so we can check them out too!  Thanks for posting all the deets!


----------



## hmscott (Jan 12, 2022)

@rev92 posted a TA-26 review thread, and a new review here:  

xDuoo TA-26
https://www.head-fi.org/showcase/xduoo-ta-26.25647/reviews


----------



## rev92

hmscott said:


> @rev92 posted a TA-26 review thread ,and a new review here:
> 
> xDuoo TA-26
> https://www.head-fi.org/showcase/xduoo-ta-26.25647/reviews


Ha, you got me!


----------



## PetFju (Jan 13, 2022)

hmscott said:
			
		

> Congratulations on your new TA-26!!



Thank you! As for all your tube recommendations and all, i've simply ordered what was most readily available and seemed like decent choices just to get me started; 
https://www.ebay.com/itm/255291800650?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
https://www.ebay.com/itm/185249082433?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
I have 0 clues as to how they sound, or what to expect, but like i said it'll get me started. 

Btw, the amp is now shipped from France (I ordered it here; https://www.audiophonics.fr/en/search?search_query=ta-26)
So price was 216€ plus shipping. Obviously i have to pay import tax (Norway) which is 25%, but so i would have to if i ordered from anywhere else. This was the cheapest i could it find atm, as it equals to 247$ USD,and also it is a reputable reseller.


----------



## hmscott

PetFju said:


> Thank you! As for all your tube recommendations and all, i've simply ordered what was most readily available and seemed like decent choices just to get me started;
> https://www.ebay.com/itm/255291800650?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
> https://www.ebay.com/itm/185249082433?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
> I have 0 clues as to how they sound, or what to expect, but like i said it'll get me started.
> ...


Both tubes look like solid choices, NIB/NOS - and not too expensive - they should sound mellower than the "sharp" stock tubes.


----------



## BubbaJay

I hadn't used my TA-20 in months and I don't think I've even used it with my iFi Neo yet so when I finally did a few days ago I was very happy to hear how good it sounds.  The NOS GE military tubes I got a while back sound great and are by far the best sounding ones I've used out of the 4 or 5 pairs I've tried.  There's the warmth you want but there's also very nice clarity and the highs have good sparkle and texture to them.  Whether I was using a dynamic driver headphone or planar they all sounded good on the TA-20.

If there are any tube recs people have let me know because I'm always down to try new ones and I prefer a more clean and clear sound over a very warm one.


----------



## hk29

Re: MT-604.  I purchased a quad set of Sylvania JHS-5654/6AK5W NOS/NIB 1952.   I have probably over 50 hours on them.  They much more refined, detailed, and provide a more space and trebly energy than the stock.  The Sylvania is a bit cleaner through the midrange.  The stock felt more "tubey" because it was more mid-centric, darker, and a bit more "fuzzier" in the midrange.  

Tube rolling is fun, but its painful trying to replace 4 small tubes in a small unit.  It is not something I want to do regularly.  I'm thinking I want to stock up on more tubes before they get even harder and more expensive to find ...

MT-604 continues to blow my mind in what you can get for $170 MSRP + $40 quad tubes.


----------



## Arghavan

kibot said:


> Privet!
> Can sombody help -  I use TA-26 with Cambridge Audio DacmagicPlus DAC and Takstar HF580 headphones with my PC as a sourse – so i hear sound distortions in high-mid and especially in high volume. Is this normal for such setup? (also i use ibasso dx 80 as a sourse and there are no sound distortions)


Tube amps especially OTL ones with high output impedance such as TA26 are not a good match with low impedance low sensitivity headphones such as these planars at all. The reason is that OTL tube amps can provide a lot of voltage but are current-starved, low sensitivity planars are current hungry and when the amp can't push these it distorts.


----------



## kibot

Arghavan said:


> Tube amps especially OTL ones with high output impedance such as TA26 are not a good match with low impedance low sensitivity headphones such as these planars at all. The reason is that OTL tube amps can provide a lot of voltage but are current-starved, low sensitivity planars are current hungry and when the amp can't push these it distorts.


Spasibo for answer!
As i said there are almoust no distortions(clipping) when i use DX80 (only in very high volume wich not intended for listening)



Some news about external noise from my TA 26 - its a transformer and I send it for repair to store where i bought it so i inform when i bring it back👌


----------



## tarikuz

I played with OTL, even if I have Senny HD800s definitvely I prefer solid state...


----------



## Ohmboy

Shared said:


> Any tube rolling recomendations? I currently use my mt 602 w ge 5654w, looking for the most tubish sound


Voskhod 6J1P-EV and Mullard M8100 are both Tubey sounding tubes so worth checking out 👍


----------



## Shane D

Thinking about getting the MT-604, but my efficient headphone collection runs from 32 to 80 Ohms. So as with my LP (probably more so), gain will be an issue. There are several options and I was curious about some feedback:

1) My two existing amps can both operate as pre-amps, but I am not sure if that will fix the problem. Won't know until I try.

2) I can pull my SMSL SU-8 DAC out of the office and run two DAC's in my system to get the volume feature. Seems kind of redundant, but certainly the cheapest outside outside of pre-amping. And I do like this DAC.

3) Attenuation. Kind of in pre-amp territory. There are inline attenuators on Amazon.ca ($45.99 X 2 and get -15Db's). Garage1217 also sells attenuators (-20Db), but it is for after the amp. It is a 4-pin XLR headphone out? With this you only need one ($45.00US), but how would the sound be affected? Pre-amp? After amp? I have no idea.

I can get this amp in Canada for $225.00. I also found a tube supplier that sells 403b's in matched sets. He has several matched sets and can recommend two similar matching pairs and all four would be about $90.00 (thanks @Wiljen). I like what I hear about this amp and the cost at about $300.00 - $350.00Cdn. seems like a decent risk. It is not dirt cheap, but everything costs more in Canada. 

Anxious to hear feedback from owners/potential owners. To be clear my biggest issues are that my headphones are Very efficient and I am not a loud listener.

Thanks.


----------



## Shane D

Ohmboy said:


> Voskhod 6J1P-EV and Mullard M8100 are both Tubey sounding tubes so worth checking out 👍


The Voshkods were my favourite tubes in the Little Dot MKIII.


----------



## jonathan c

Shane D said:


> Thinking about getting the MT-604, but my efficient headphone collection runs from 32 to 80 Ohms. So as with my LP (probably more so), gain will be an issue. There are several options and I was curious about some feedback:
> 
> 1) My two existing amps can both operate as pre-amps, but I am not sure if that will fix the problem. Won't know until I try.
> 
> ...


•  The headphone input impedance alone should not pose a gain issue. Take a look at headphone sensitivity: in dB/mw or in dB/V (which takes impedance into account).
•  Your headphone impedance range of 32 ohms to 80 ohms is not unusual. What is unusual is the LP volume knob/circuitry. I could never tolerate anything on the LP close to “ten o’clock”! 😵‍💫


----------



## Shane D

jonathan c said:


> •  The headphone input impedance alone should not pose a gain issue. Take a look at headphone sensitivity: in dB/mw or in dB/V (which takes impedance into account).
> •  Your headphone impedance range of 32 ohms to 80 ohms is not unusual. What is unusual is the LP volume knob/circuitry. I could never tolerate anything on the LP close to “ten o’clock”! 😵‍💫


My LP is gone now. Due to my collection, OTL amps are no use to me. I would like a little tube amp with a fun sound to add to the collection. But if my Grado's can't go much past 8:00, what's the point?


----------



## AudioCats

Shane D said:


> My LP is gone now. Due to my collection, OTL amps are no use to me. I would like a little tube amp with a fun sound to add to the collection. But if my Grado's can't go much past 8:00, what's the point?



hybrid amps typically use the tube to do voltage gain, this gain is typically not needed for low impedance phones. 

Maybe consider a tube amp with output transformers? (wooaudio WA6 etc)


----------



## Shane D

AudioCats said:


> hybrid amps typically use the tube to do voltage gain, this gain is typically not needed for low impedance phones.
> 
> Maybe consider a tube amp with output transformers? (wooaudio WA6 etc)


Woo stuff looks nice, but it is about five times the price.

I like the look of Woo, but for those prices I would Really have to love the sound.


----------



## AudioCats

my main point was that an "output transformer coupled" amp will be more suitable for low z phones, especially if you don't listen loud.


----------



## Shane D

AudioCats said:


> my main point was that an "output transformer coupled" amp will be more suitable for low z phones, especially if you don't listen loud.


I'll look into it thanks.

I had an SET amp from MAD that was great for my Grado's, but didn't really move me.

Just looking for cheap fun.


----------



## PetFju

I just recieved my TA-26 yesterday. Here are a couple of first impressions 

First power up and listen; Sounds like complete and utter horses***.. Hardly any bass, muddy mids and heavily veiled highs..

It's now been on for a few hours, and the change has been nothing short of dramatic. Everything has opened and tightened up, and there is bass. Not the "kick you in the nuts" kind of bass, but at least bass. 
Not even a hint of what some has referred to as sharp highs though. Just a very comfortable sound, with a big soundstage. And i guess there is more to come, based on the fact that the amp has only been on for 8-10 hours and playing maybe three-four of them. Looking forward to it!

But boy oh boy does it get hot.. This is a space heater! 





Looks good!  I'll post an update after a few more hours of listening.


----------



## alexeyi

PetFju said:


> I just recieved my TA-26 yesterday. Here are a couple of first impressions
> 
> First power up and listen; Sounds like complete and utter horses***.. Hardly any bass, muddy mids and heavily veiled highs..
> 
> ...



Mine started sounding “right” after 50 hours mark, so be patient with it. It will open up nicely.


----------



## PetFju (Jan 20, 2022)

alexeyi said:


> Mine started sounding “right” after 50 hours mark, so be patient with it. It will open up nicely.


I hope (and expect so). I also recieved my RCA 6AS7G and put it in for s***s and giggles. I percieve a sound with softer edges and possible even more space, but it's subtle. I'll swap back to the stock tube after a while to see what i can pick out regarding differences.
I also ordered another tube, based on nothing but a hunch. Hopefully it'll sound good; https://www.ebay.com/itm/313314773875?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
Does anyone have any experience with this or other JAN tubes for this amp? I've found that JAN tubes normally sound clear and strong in most amps/configs, and that is the hope for this one as well.


----------



## kibot

PetFju said:


> I hope (and expect so). I also recieved my RCA 6AS7G and put it in for s***s and giggles. I percieve a sound with softer edges and possible even more space, but it's subtle. I'll swap back to the stock tube after a while to see what i can pick out regarding differences.
> I also ordered another tube, based on nothing but a hunch. Hopefully it'll sound good; https://www.ebay.com/itm/313314773875?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
> Does anyone have any experience with this or other JAN tubes for this amp? I've found that JAN tubes normally sound clear and strong in most amps/configs, and that is the hope for this one as well.





PetFju said:


> I just recieved my TA-26 yesterday. Here are a couple of first impressions
> 
> First power up and listen; Sounds like complete and utter horses***.. Hardly any bass, muddy mids and heavily veiled highs..
> 
> ...


My congrats , друг!!!!✨✨✨👍


----------



## PetFju

kibot said:


> My congrats , друг!!!!✨✨✨👍


Thanx! I am looking forward to seeing how this amp performs going forward.


----------



## Halimj7

Looking for recommendations for a really warm and lush tube amp or amp/Dac combo. I have a Sony TA-Z1Hes and DMP-Z1. Im looking for something warmer (via an increased low end) and smoother in the upper mids and highs and without bringing the mids too forward. I don’t care too much about resolution or power it will be primarily for my Audiotechnica AWAS. Ideal price would be less than $2000. Thanks.


----------



## ColSaulTigh

Halimj7 said:


> Looking for recommendations for a really warm and lush tube amp or amp/Dac combo. I have a Sony TA-Z1Hes and DMP-Z1. Im looking for something warmer (via an increased low end) and smoother in the upper mids and highs and without bringing the mids too forward. I don’t care too much about resolution or power it will be primarily for my Audiotechnica AWAS. Ideal price would be less than $2000. Thanks.


For that price range, look at a Woo Audio WA6-SE.  I know there's a user on here selling one for well under your budget.


----------



## Shane D

Halimj7 said:


> Looking for recommendations for a really warm and lush tube amp or amp/Dac combo. I have a Sony TA-Z1Hes and DMP-Z1. Im looking for something warmer (via an increased low end) and smoother in the upper mids and highs and without bringing the mids too forward. I don’t care too much about resolution or power it will be primarily for my Audiotechnica AWAS. Ideal price would be less than $2000. Thanks.


Recently watched a Zeos review and he was very impressed with a new Woo DAC/Amp called, I think, the WA7, third gen. I know warm and lush is in the ear of the listener, but it looks cool, there is only one piece and the price is $1,399.00.


----------



## Audiophile PT

Halimj7 said:


> Looking for recommendations for a really warm and lush tube amp or amp/Dac combo. I have a Sony TA-Z1Hes and DMP-Z1. Im looking for something warmer (via an increased low end) and smoother in the upper mids and highs and without bringing the mids too forward. I don’t care too much about resolution or power it will be primarily for my Audiotechnica AWAS. Ideal price would be less than $2000. Thanks.


I also have the TA-ZH1ES and was also looking for something warmer (to smooth the treble region of my Meze Liric).
Meanwhile I decided to get the TubeAmp Xduoo TA-20 and I'm enjoying it a lot.
Right now I have it paired with RME ADI-2 DAC and I must say that I'm really pleased with the sound from that pairing.
I've replaced the stock tubes and now I'm using Psvane Art Series Tubes.
The TA-ZH1ES is paired with another TubeAmp (Loxjie P20 with GE5670 Tubes) and although the resulting sound is good but not as good as with the Xduoo TA-20.


----------



## hmscott (Jan 25, 2022)

PetFju said:


> I just recieved my TA-26 yesterday. Here are a couple of first impressions
> First power up and listen; Sounds like complete and utter horses***.. Hardly any bass, muddy mids and heavily veiled highs..
> It's now been on for a few hours, and the change has been nothing short of dramatic. Everything has opened and tightened up, and there is bass. Not the "kick you in the nuts" kind of bass, but at least bass.
> Not even a hint of what some has referred to as sharp highs though. Just a very comfortable sound, with a big soundstage. And i guess there is more to come, based on the fact that the amp has only been on for 8-10 hours and playing maybe three-four of them. Looking forward to it!
> ...


Congratulations!! 

What are the headphones you are using to burn-in the TA-26?  Using the Sennheiser HD660S on the TA-26; with the NOS/NIB Sylvania VT-231 6SN7GT and Sylvania 6SN7GTA tubes, I get plenty of Bass! 


Spoiler: TA-26 volume knob travel



As I've mentioned before the TA-26 volume knob may not need to move very far with a full RCA 2V input voltage from a DAC, or other device, when listening with lower than 600 ohm impedance headphones.

My primary listening has been using the Sennheiser HD660S on the TA-26, with only 150 ohm impedance.  I can run at the full 2V output of the Topping D90 MQA DAC, but I am limited to a short amount of volume knob movement.  That doesn't bother me, and the TA-26 ALPS volume control is clean and precise so I can make very small movements to fine tune the volume setting.  But, that won't be "Normal" for most people, and that might be difficult to accept.

 I cannot "crank up the power" - move the volume dial a large distance - but with the volume knob travel available I get the same full Bass sound earlier in the volume knob range of movement, so the sensation of "cranking it up" is missing, but the same Full Bass sound is there.

If I attenuate my D90 DAC output by -20dB then I get much more travel in the TA-26 Volume knob, and I can actually "crank it up" to over 12 o'clock, but actually the sound is the same as with the Full 2V DAC output, but the sensation of "cranking it up" isn't there.

It took me a little while to get used to the +0dB Full Output of my D90 into the TA-26, and "learn to Love" the short travel of the Volume knob, and I am still finding myself setting attenuation on the D90 to -20dB, then -15dB, then -10dB, then -5dB, simply to prove to my "Lizard brain" that it is indeed, the same at any attenuation - it is simply getting accustom to the small amount of Volume knob travel. 

I can see how some simply give up and exclaim, I can't turn the *(&*& Volume Up!! 
But, the TA-26 sound I am enjoying is well worth retraining my "Lizard Brain" to accept this strange volume dial "Rocking Reality".  


*Update: *I've been avoiding listening to IEM's on the TA-26 due to their typically lower than 64 ohm impedance, but now that I've received a review tour set of the *SeeAudio X Crinacle Yume Midnight *IEMs from Hifigo.com - I couldn't resist trying them on the TA-26, they Rock!

I was pleasantly surprised to find that the 32 ohm *Midnight *IEMs sounded so good on the TA-26, and there is no added noise from the TA-26! Together the *Midnight *IEM and TA-26 have a black 'noiseless" background together, even with the TA-26 volume up all the way!

I have also listened to the *Midnight *on the Xduoo TA-20 and Fiio M15, and in comparison, the 32 ohm _*Midnight *_sounds completely "normal" on the TA-26, but with that TA-26 tube sound!

I'll pull out my "watch case" of various favorite IEMs over the next 2-3 weeks to compare to the *Midnight*, and enjoy on them all on the TA-26 too! It is all very exciting to find that I can enjoy my IEM's on the TA-26 too! 

*Update*: Interestingly, with such a low impedance of 32 ohms, the *SeeAudio X Crinacle Yume Midnight *IEMs on the TA-26, I am playing and comparing between +0dB, -10dB, and -20dB attenuation settings on the Topping D90 in Pre-Mode, I am finding *more" volume dial movement available with the *Midnight ...*more later.


----------



## PetFju

hmscott said:


> Congratulations!!
> 
> What are the headphones you are using to burn-in the TA-26?  Using the Sennheiser HD660S on the TA-26; with the NOS/NIB Sylvania VT-231 6SN7GT and Sylvania 6SN7GTA tubes, I get plenty of Bass!



Thank you 

For the most part i am using Sennheiser 58X's. I Must say that bass has improved dramatically since first listen. Also my RCA tubes have arrived, and has replaced the stock tubes. They already seem better in all respects really, but i'll swap back after a while to confirm. 

BTW; 6SN7GTA -> i know there are loads of different variations to this tube, but i was unsure as to anything after the 6SN7GT (A or B or whatever). Is there a list somewhere of all compatible tubes?

-P-


----------



## alexeyi

hmscott said:


> Congratulations!!
> 
> What are the headphones you are using to burn-in the TA-26?  Using the Sennheiser HD660S on the TA-26; with the NOS/NIB Sylvania VT-231 6SN7GT and Sylvania 6SN7GTA tubes, I get plenty of Bass!
> 
> ...



I also listened to some lower impedance headphones in pairing with TA-26, most of them sound really good, with a warm added signature, specific to tubes. 

I can say that in my listening experience, headphones over 120Ohm are the better experience overall, but using lower than 64Ohm is definitely possible and maybe a nice surprise.


----------



## hmscott (Jan 25, 2022)

PetFju said:


> Thank you
> 
> For the most part i am using Sennheiser 58X's. I Must say that bass has improved dramatically since first listen. Also my RCA tubes have arrived, and has replaced the stock tubes. They already seem better in all respects really, but i'll swap back after a while to confirm.


Yup, it takes time to get our heads wrapped around the whole sound change, controls, and tube burn-in progression timing, the TA-26 is similar to the TA-20 in many ways, yet very different in so many other ways. 


PetFju said:


> BTW; 6SN7GTA -> i know there are loads of different variations to this tube, but i was unsure as to anything after the 6SN7GT (A or B or whatever). Is there a list somewhere of all compatible tubes?
> 
> -P-


There are a bunch of threads here on head-fi covering *the 6SN7*

"*The Reference 6SN7 Thread"* 1st post listing has a ton of useful "6SN7 Reference" Info 
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-1380036

Here is the first part, the quick description list of 6SN7 tubes:

*6SN7GT* *- First designation of the 6SN7 tube type. ‘G’ = glass body & ‘T’ = short bottle.
*6SN7W* / 6SN7A* / 6180* *- 10000hrs minimum life. Often labeled with JAN-CHS (equals Sylvania-made military stock) The A is generally a taller bottle with the mica above the metal band while the W has the bottom mica a bit below the metal band. But it's common to find both labelled as each other also.
*6SN7GTA* *- 'Upgrade' of 6SN7GT, max 450Volt Ua, 5W per system and 7.5W total. Hence tube better fulfills special requirements for TV sweep applications, like higher peak power and better impulse capabilities.
If your amp is designed around this tube, you MAY NOT be able to substitute in other 6SN7 versions due to the higher ratings for this tube – check with your manufacturer.
*6SN7GTB* *- Same as GTA, but with faster tube heat-up (11 seconds only).
If your amp is designed around this tube, you MAY NOT be able to substitute in other 6SN7 versions due to the higher ratings for this tube – check with your manufacturer.
*6SN7GTC* *- Metal envelope type 6SN7 [ie. glass envelope replaced by a metal cap]. Not well regarded. From Audio Asylum: _”South American trash can style 6SN7, 1970's vintage, pure rubbish, I wouldn't even count on it really being a 6SN7 as the South American tube makers were fairly...'liberal'...with their use of tube numbers.” –Robert H_
If your amp is designed around this tube, you MAY NOT be able to substitute in other 6SN7 versions due to the higher ratings for this tube – check with your manufacturer.
*6SN7GTY* *- Only found on 6SN7GTs with brown ‘low-loss’ Micanol bases. RCA (US - lighter brown) and Brimar (British - darker brown) made GTYs.
*6SN7WGT* *- Military version of the 6SN7GT; 10,000hrs minimum life (up for debate). _“IMO, while tubes (like car engines or light bulbs) may be rated for a specific lifetime, a LOT depends on the actual usage type and pattern the tube will see. E.g. Switch your amp on/off 10 times a day? Don’t expect 10,000hrs.”_ -Author
*6SN7WGTA* *- Military version of 6SN7GTA.
*6SN7WGTB* *- Military version of 6SN7GTB.

*VT-231* *- Military Part number for 6SN7. Part number used until 1945 - hence presence of this designation is usually a guarantee for real old tubes.
*JAN-XXX-6SN7** - JAN= Joint Army Navy. Factories conducted stress tests (above normal 'civilian' specs) on samples of standard tubes. If they survived, the whole lot would be approved (batch approval), and marked with the prefix JAN. The samples that are actually used for the stress tests are discarded. *Do remember that the stress tests conducted were on SMALL samples. “ Very interesting thing nobody talks about - especially dealers who have made a living buying old military stock that occasionally pops out of warehouses. What did the government do with tube shipments they received where their spot testing results were not acceptable? Well, in some cases, they sent them back, whereupon the manufacturer sold them into the secondary markets. A lot of those are still floating around today. OR - the government stuck the shipment into a warehouse, and in typical bureaucratic fashion, forgot about them - until some SoCal slickster approaches them with a great offer. Bingo! They are back on the market as super-duper cold war commie beating top grade mil-spec tubes - and sold to you and I, who don't realize that they probably failed the spec test. The VT or JAN designations have too often been assumed in tube folklore to be better tubes. In reality, they may be the rejects. I have occasionally found FIELD STOCK in foreign countries left behind after a war. This is the primo stuff. Not the stuff sitting in a US or UK warehouse.” –Robert H. [PHOTO HERE]
5692 *- Military part number for a 'shock-proof' tube. Introduced 1948. The famous RCA "red base" is a 5692. Weight is much higher, and tube construction differs from 6SN7s. 275V maximum plate voltage & maximum 1.75W per section. *[PHOTO HERE]

33S30A* / 33S30B** - Swedish military versions of the 6SN7. Very _very_ rare and sought after.
*ECC31, 32, 33, 34* - Popular MISconception: these are *NOT *equivalent to 6SN7. Especially the ECC32/CV181 - close, but the 50% higher current draw will probably fry some transformers. Grid voltage, gain and transconductance are all different for these tubes. Ask your amp manufacturer first before substituting these in.
*CV181/CV2821* – Alternate designations for ECC32/ECC33 respectively. The popular Mullard CV181 is NOT a drop-in replacement for 6SN7s – 50% more power draw means that the tube will probably send your transformer up in smoke.
*1633/6042* - 25V/0.15A heater version of the 6SN7.
*6N8S** - Old Russian designation for the 6SN7. Some Eastern European and Chinese tube factories still use this designation.
*6H8C* - Russian designation for a 6SN7 with a higher plate voltage. *[PHOTO HERE]
13D2* - Europe-only 'special quality' version of the 6SN7GT. The tube is reinforced for additional mechanical rigidity. *[PHOTO HERE]
CV1986* / CV1988* *- Both are the UK Government Common Valve designation for the 6SN7GT. *[PHOTO HERE]
CV2627* *- UK Government Common Valve designation for the 6SN7W.
*B65** - 6SN7 replacement made by Marconi/Osram/GEC. _Extremely _rare and sought after. *[PHOTO HERE]
7N7 *- Electrically IDENTICAL to the 6SN7 tube. This tube has a loctal-base. To fit a 6SN7 socket, a loctal-socket-to-octal-base adaptor must be fashioned. Why loctals? These tubes were created (and strongly advocated by RCA and Philco) for use in high-frequency radio applications, where the longer wires present in normal 6SN7 bases were causing problems by picking up interference. *[PHOTO HERE]"

There is a ton more info in that 1st Post, and the whole thread, check it out here:*

"*The Reference 6SN7 Thread"* 1st post listing has a ton of useful "6SN7 Reference" Info 
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-1380036

I read up, see photo's, and post in the "*6SN7 Tube Addicts*" thread:
https://www.head-fi.org/threads/6sn7-tube-addicts.479031/post-16772217
https://www.head-fi.org/threads/6sn7-tube-addicts.479031/post-16772903

And, for the other TA-26 tube - the 6AS7G - here is the "*For 6AS7G tube rollers here .....*" thread, and it's first post has a great list of 6AS7G variants!
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

*"6080 - low gain @ 2- great vocals, wide sound staging

7236 - medium gain - great bass, fast and dynamic. Almost SS sounding

5998A - medium gain in straight bottle. Plate construction like 6AS7.

5998 - medium gain at 5, full-bodied sound, same current load as 6AS7

421A - same as 5998 but with matched plates/sections

6AS7G - low gain, the standard tube for most, plentiful

6AS7GA - low gain, like the standard 6AS7G in straight bottle

6520 - premium 6SA7G, sometimes with 5998 plates

6H13 - Russian 6AS7G equivalent. nothing magical with these

ECC230 - European 6AS7G equivalent. haven't seen one in person

6528 - equiv to 5998 but very high gain at 9, twice the current load. Make sure you amp can handle it

6336 - like 6528 but low gain at 2, still twice current load. Make sure you amp can handle it"*


----------



## PetFju

hmscott said:


> There are a bunch of threads here on head-fi with *posts concerning the 6SN7*



Holy S***.. OK! Thank you!


----------



## PetFju

I have another question for the TA-26 owners out there; I have a bit of an issue with transformer hum through the headphones. 
Nothing major, but noticeable. And when there's no sound playing it's quite audible. 
Is this a common problem (ref. @kibot 's issue)? There's no noise from the amp itself, only through the headphones. 
And my amp is connected to the mains via a light filter which should help with a lot of HF noise and DC etc, but there could be grounding issues within the amp that might not be all that uncommon?


----------



## alexeyi (Jan 25, 2022)

PetFju said:


> I have another question for the TA-26 owners out there; I have a bit of an issue with transformer hum through the headphones.
> Nothing major, but noticeable. And when there's no sound playing it's quite audible.
> Is this a common problem (ref. @kibot 's issue)? There's no noise from the amp itself, only through the headphones.
> And my amp is connected to the mains via a light filter which should help with a lot of HF noise and DC etc, but there could be grounding issues within the amp that might not be all that uncommon?



I also experienced some 'hum' mainly in the right earcup with smaller impedance headpones.
It started to dim and disappear in the end after around 40 hours of burn-in.

With heaphones having 600Ohm impedance, I could not hear it at all, from the start.

You could try what @hmscott suggested below, you might experience a hum related to something else.


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## hmscott (Jan 25, 2022)

PetFju said:


> I have another question for the TA-26 owners out there; I have a bit of an issue with transformer hum through the headphones.
> Nothing major, but noticeable. And when there's no sound playing it's quite audible.
> Is this a common problem (ref. @kibot 's issue)? There's no noise from the amp itself, only through the headphones.
> And my amp is connected to the mains via a light filter which should help with a lot of HF noise and DC etc, but there could be grounding issues within the amp that might not be all that uncommon?


It is coming through the RCA cable from your DAC - passed through ground leakage from it or other devices, as it did from my D90 MQA DAC previously with my Topping A90 when connected with RCA to my D90 MQA.

*If you fully disconnect the RCA cable(s) from your DAC to your TA-26 - pulled out from the back of the TA-26 - does the hum in your headphones connected to the TA-26 stop completely, even with the volume up all the way?  It should.*

The noise passed through the RCA / USB cables will vary based on a lot of factors.  One day you may hear little to no hum/noise, and after someone turns on or plugs in other electronics nearby, or you game on your PC, you may get a lot more noise at another time.

When I bought my Topping A90 + D90 MQA I went through a lot of "pain" getting rid of noise carried in via RCA and USB cables - not so much hum as EMI/RFI Noise and GPU noise from my PC induced into my D90 DAC via the USB cable +5v power wires.

I got rid of all the noise by getting heavily shielded cables, and a modified USB power/ground interruption/lift solution - iFi Audio iDefender+

For the hum you are hearing I would try a Worlds Best Cables RCA cable:

*1 Foot – Directional Quad High-Definition Audio Interconnect Cable Pair Custom Made by WORLDS BEST CABLES – Using Mogami 2534 Wire and Amphenol ACPR Die-Cast, Gold Plated RCA Connectors $31*
https://www.amazon.com/Foot-Directional-High-Definition-Interconnect-Connectors/dp/B01ALHTVMO

The cable/wire description is from Mogami:





The design description from WBC comes down to lifting the shield ground at the destination end.  That keeps the shield borne induced noise out of the TA-26:




The WBC RCA cables got rid of all the of the Topping A90 RCA noise except for the PC GPU noise borne by the USB power wires (iDefender+ got rid of that).  I also have a $100+ filtered power strip, but with that alone, before the WBC cables and iDefender+, the filtered power strip wasn't enough to get rid of all the noise.

During normal listening with the TA-26 Volume knob at the highest listenable setting, with or without music, I don't hear any hum.

Sometimes, I can get barely detectable hum coming through the TA-26 RCA cable at 100% Volume with the WBC RCA cable connected from the D90 MQA in DAC-mode with full RCA Voltage output, but when I use the D90 Pre-Mode attenuation on the Topping D90 MQA DAC, there is no Hum detectable at all with 100% Volume.

If you have hum/noise coming through your RCA cable(s) (check by disconnecting from TA-26), please try the WBC RCA cables built with Mogami 2534 Quad Twisted Conductors (WBC have various pre-built lengths), and see if that is enough of a diminution of the hum/noise for your situation. 

Note: I have run my A90/D90 on a RavPower RP-BP187 with PureSine wave 300w AC power, without "mains power", the A90 / D90 ran even quieter - there is no ground connection external to the RP-BP187 when run "offline" in battery mode, which runs them both for about 10-12 hours.  The power brick that comes with the RP-PB187 doesn't have a ground connection either, and so I could also run in power passthrough mode - charging at the same time - and it would run 100% quiet endlessly 

Warning: When running on Mains AC power, I don't recommend using cheater plugs to "lift the ground pin" to get rid of "hum" or "ground loops", you can get into trouble if you accidentally connect a grounded device into that ungrounded system and a "ground loop" is created, so please don't do that.

IDK if I am going to spend time tracking down my hum source since it is at such a very low level that I'll never hear it while listening on the TA-26, but maybe I could try some solutions for those of you that have it much worse.


----------



## PetFju

hmscott said:


> It is coming through the RCA cable from your DAC - passed through ground leakage from it or other devices, as it did/does from my D90 MQA DAC previously with my Topping A90 when connected with RCA to my D90 MQA.
> 
> *If you fully disconnect the RCA cable(s) from DAC to your TA-26 - pulled out from the back of the TA-26, does the hum in your headphones connected to the TA-26 stop completely, even with the volume up all the way?  It should.*
> 
> ...


Yea, i am not unused to these kinds of issues, as i am an "old hifi nerd". And as such i've gotten some decent cables (Wireworld  cables all around) as well as a Topping HS01 galvanic isolator for the USB. The HS01 takes care of a lot of issues actually.
The hum is still there if i disconnect the RCA cables, which is why i believe it originates within the amp somehow. With that said i could try some different power cables to see if there's any kind of RFI or whatever getting in that way. 
But thanks for the response! I know a lot of people modify their DV amps for this reason, and that was actually one of the reasons i got the TA-26 in stead of a DV, cause it simply seem to be a better built amp. 
I'll do some digging to see what may alleviate it, but so far i think i can exclude groundloop issues based on the disconnect in usb and the DAC which has a non-grounded psu (RME adi-2 fs).


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## Shane D

I ordered the MT-602 last night from Apos. It would have been five weeks from Amazon.ca. I also ordered JAN 5654W's and Voshkods from Amazon since I had a gift card.

I was looking for some cheap fun and this is it. Now, just the waiting.


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## hmscott (Jan 25, 2022)

PetFju said:


> Yea, i am not unused to these kinds of issues, as i am an "old hifi nerd". And as such i've gotten some decent cables (Wireworld  cables all around) as well as a Topping HS01 galvanic isolator for the USB. The HS01 takes care of a lot of issues actually.
> The hum is still there if i disconnect the RCA cables, which is why i believe it originates within the amp somehow. With that said i could try some different power cables to see if there's any kind of RFI or whatever getting in that way.
> But thanks for the response! I know a lot of people modify their DV amps for this reason, and that was actually one of the reasons i got the TA-26 in stead of a DV, cause it simply seem to be a better built amp.
> I'll do some digging to see what may alleviate it, but so far i think i can exclude groundloop issues based on the disconnect in usb and the DAC which has a non-grounded psu (RME adi-2 fs).


Yup, if you are getting hum without the RCA connection, it's coming from your power / ground, or one of your tubes is exhibiting the hum some people have reported with tube-rolling new tubes on the Darkvoice.


alexeyi said:


> I also experienced some 'hum' mainly in the right earcup with smaller impedance headpones.
> It started to dim and disappear in the end after around 40 hours of burn-in.
> 
> With headphones having 600Ohm impedance, I could not hear it at all, from the start.
> ...


@alexeyi - I have heard that tube "burn-in" reduces hum, but it was for certain tubes when tube rolling on the DarkVoice, and the TA-26 is supposed to have carefully selected tubes to keep their customers from worrying about "new tube" problems, if they stick with the stock tubes.


----------



## alexeyi

hmscott said:


> Yup, if you are getting hum without the RCA connection, it's coming from your power / ground, or one of your tubes is exhibiting the hum some people have reported with tube-rolling new tubes on the Darkvoice.
> 
> @alexeyi - I have heard that tube "burn-in" reduces hum, but it was for certain tubes when tube rolling on the DarkVoice, and the TA-26 is supposed to have carefully selected tubes to keep their customers from worrying about "new tube" problems, if they stick with the stock tubes.
> 
> ...



It is not my first tube amp, so I knew what I have to do, but you might be right. Since then, I changed the stock tubes, so I can’t check that anymore, but thanks for the hint


----------



## PetFju

For me the stock tubes makes no difference when it comes to the hum. Maybe the transformer is having issues with the 230-240v that comes out of the outlet here, as opposed to the 220v often specced into electrical devices for the general European market. 
It really shouldn't though, as it is well within spec for the grid to run a little hot, but still. 
Who knows. It's not an issue with either my TA-20 or my Little Dot Mk1+, which brings me back to the amp/transformer itself. 
Anyways, it's not "bad" by any means, i can live with it just fine, so if i can't figure it out or remedy it it's not that big a deal.


----------



## alexeyi

PetFju said:


> For me the stock tubes makes no difference when it comes to the hum. Maybe the transformer is having issues with the 230-240v that comes out of the outlet here, as opposed to the 220v often specced into electrical devices for the general European market.
> It really shouldn't though, as it is well within spec for the grid to run a little hot, but still.
> Who knows. It's not an issue with either my TA-20 or my Little Dot Mk1+, which brings me back to the amp/transformer itself.
> Anyways, it's not "bad" by any means, i can live with it just fine, so if i can't figure it out or remedy it it's not that big a deal.



You should give it a little more time, then, if the issues is still present, send back the unit.


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## hmscott (Jan 25, 2022)

PetFju said:


> For me the stock tubes makes no difference when it comes to the hum. Maybe the transformer is having issues with the 230-240v that comes out of the outlet here, as opposed to the 220v often specced into electrical devices for the general European market.
> It really shouldn't though, as it is well within spec for the grid to run a little hot, but still.
> Who knows. It's not an issue with either my TA-20 or my Little Dot Mk1+, which brings me back to the amp/transformer itself.
> Anyways, it's not "bad" by any means, i can live with it just fine, so if i can't figure it out or remedy it it's not that big a deal.





alexeyi said:


> You should give it a little more time, then, if the issues is still present, send back the unit.


It might be outside of your return window if you wait too long. IDK how long you have to do a return vs an RMA repair from your seller.

You might consider asking Xduoo support, as they are the experts on the design and support for their hardware 

service@xduoo.com - I'd make a short explanation that is clear and to the point, basically stating your voltage/frequency locally vs what the particular build of TA-26 is spec'd to expect, and see what they suggest as a solution to the mismatch.

I've seen people buy voltage/cycle matching hardware to solve similar problems, but I don't have any experience with those issues myself, so I don't have any specific solutions to recommend.

It is possible Xduoo could suggest a simple parts mod to match that TA-26's power setup to your own, or it might require RMA to replace the transformer to one that matches your local voltage/frequency.


----------



## PetFju

Just read this on the drop forum about the DV amp; "Where I see a tube lifespan destroying 7v from the trafo instead of the normal 6.3v, someone on 230v operating gear with a 220v trafo would see something closer to 6.5v which is a bit hot but within the generally ok range for heaters. Excess heater AC voltage will cause very unpleasant mains noise, thus the nasty 60hz. x_X" https://drop.com/buy/xduoo-ta-26-tube-headphone-amplifier/talk/2828859 
Another tip from forum.hifiguides.com seems to be to run the amp without the powertube for a day or three, and that solves the issue for some people; https://forum.hifiguides.com/t/xduoo-ta-26-tube-amplifier/26808/15


----------



## alexeyi

PetFju said:


> Just read this on the drop forum about the DV amp; "Where I see a tube lifespan destroying 7v from the trafo instead of the normal 6.3v, someone on 230v operating gear with a 220v trafo would see something closer to 6.5v which is a bit hot but within the generally ok range for heaters. Excess heater AC voltage will cause very unpleasant mains noise, thus the nasty 60hz. x_X" https://drop.com/buy/xduoo-ta-26-tube-headphone-amplifier/talk/2828859
> Another tip from forum.hifiguides.com seems to be to run the amp without the powertube for a day or three, and that solves the issue for some people; https://forum.hifiguides.com/t/xduoo-ta-26-tube-amplifier/26808/15



If you would live in North America or Japan, then I could understand the 60Hz concern, but not in Europe.

I would go for the second option described in your post, but it is up to you.


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## PetFju (Jan 26, 2022)

alexeyi said:


> If you would live in North America or Japan, then I could understand the 60Hz concern, but not in Europe.
> 
> I would go for the second option described in your post, but it is up to you.


Only difference is that our grid is 50hz and not 60, if i am not mistaken. The issues could still very well be similar, depending on the trafo.
However, i agree with you about the solution. I will give this some time, see if the issue goes away on its own, or try the "no powertube" option.

And i think this only bugs me because i've spent way too many years with hifi equipment which costs *many* times more than the TA-26, and so i am used to critical listening.
Ironically that's what i hoped to remedy with Head-Fi, and tubes in particular; to bring back the pleasure of just listening to music, in stead of analyzing every sound and note. I guess i am tainted by experience in this regard, and fixing this won't come that easy 
Anyway; it's not a big deal, simply noticeable when there's no sound playing, and i am quite certain a lot of people wouldn't even notice.


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## Audiophile PT (Jan 26, 2022)

hmscott said:


> Yup, it takes time to get our heads wrapped around the whole sound change, controls, and tube burn-in progression timing, the TA-26 is similar to the TA-20 in many ways, yet very different in so many other ways.
> 
> There are a bunch of threads here on head-fi covering *the 6SN7*
> 
> ...



Excellent post with valuable info of tubes for the TA-26.
As a newcomer to TubeAmp world I would love to see a similar post for the TA-20


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## hmscott (Jan 26, 2022)

Audiophile PT said:


> Excellent post with valuable info of tubes for the TA-26.
> As a newcomer to TubeAmp world I would love to see a similar post for the TA-20


There exists such info out there - I dug it up when I started looking for 12xx7 headphone amps - before I decided on the Xduoo TA-20 and that info helped me decide on the Xduoo TA-20. It'll take me a little while to pull it together again, but I'll drop some as I find it 

I'm sure there are a bunch of others out there with a TA-20 that would be able to contribute their favorites


----------



## hmscott (Jan 27, 2022)

Shane D said:


> Thinking about getting the MT-604, but my efficient headphone collection runs from 32 to 80 Ohms. So as with my LP (probably more so), gain will be an issue. There are several options and I was curious about some feedback:
> 
> 1) My two existing amps can both operate as pre-amps, but I am not sure if that will fix the problem. Won't know until I try.
> 
> ...


...

I don't have an MT-602/MT-604, but they look great - each with their own special character, the MT-604 I find especially fascinating as I love balanced + independent volume control, most are missing right/left balance controls.

IDK if you've found these threads on head-fi:

xDuoo MT-602 Tube Class-A Headphone Amplifier - pages of reviews + comments clustered at the end of each page
https://www.head-fi.org/showcase/xduoo-mt-602-tube-class-a-headphone-amplifier.25046/
https://www.head-fi.org/showcase/xduoo-mt-602-tube-class-a-headphone-amplifier.25046/reviews

xDuoo MT-602 hybrid headphones amplifier review


xDuoo MT-604 Balanced Tube - 3 pages of reviews + comments clustered at the end of each page 
https://www.head-fi.org/showcase/xduoo-mt-604-balanced-tube.25147/
https://www.head-fi.org/showcase/xduoo-mt-604-balanced-tube.25147/reviews

Xduoo MT-604 tube amp, My Thoughts...


As far as attenuation, any added device in the signal path will affect the sound.  Some attenuation can improve the experience of adjusting the volume and it takes time to find what your hearing responds to positively, which can change over time too, it's all a journey of discovery.


----------



## Shane D

hmscott said:


> I don't have an MT-602, but it looks great, especially as I love balanced + independent volume control, most are missing right/left balance controls.
> 
> IDK if you've found these threads on head-fi:
> 
> ...



Yes sir. I went through every review and thread that I could find online. I ended up ordering the 602 as the price and tube rolling would be much cheaper. Also my RCA switcher has an opening and I sold my XLR switcher with my LP.

Curious to play with it and see how the high gain works out.


----------



## hmscott (Jan 26, 2022)

Shane D said:


> Yes sir. I went through every review and thread that I could find online. I ended up ordering the 602 as the price and tube rolling would be much cheaper. Also my RCA switcher has an opening and I sold my XLR switcher with my LP.
> 
> Curious to play with it and see how the high gain works out.


That's great 

I am funny how I post things, I start by posting what is found first, then when I have something I don't want to lose written up, I post it, but I continue the thought and keep adding to it.  Sometimes (often), I go back and edit it again and again, catching typo's and errors myself, and adding Updates.

You read it when I hadn't finished yet, so perhaps check it out again later... still editing.  I should really put an "editing" comment in the post while I am still adding to it, but in the end I'd almost have to leave that "editing" note there for a looong time 

Congrats on the new MT-602!  I hope you really do enjoy it, and find some great tube discoveries along the way!  For me it has really helped the "pandemic" go by with more joy while passing the time in lockdown(s).


----------



## Blackrao

I checked out the xDuoo MT-604 its suppose to have a Class A buffer, which not sure if that matters much in this case, and is a hybrid tube balanced tube amp. The power output this thing puts out is pretty crazy I barely have to turn the dial. I tried sennheiser on tubes since everyone always talks about how much they like that, and I feel like the hd 58x pairs pretty well due to higher impedance 150 and sound signature


----------



## PetFju (Jan 27, 2022)

hmscott said:


> There exists such info out there - I dug it up when I started looking for 12xx7 headphone amps - before I decided on the Xduoo TA-20 and that info helped me decide on the Xduoo TA-20. It'll take me a little while to pull it together again, but I'll drop some as I find it
> 
> I'm sure there are a bunch of others out there with a TA-20 that would be able to contribute their favorites


@Audiophile PT

On this note; I just picked up my Philips Miniwatt E180CC SQ tubes (https://www.ebay.com/itm/133642391945?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649) 12AT7 equivalents to be used in my TA-20.
First impression (probably no surprise here..) is that i could have just not bothered buying any of the other tubes i have for this amp.
I would have saved (quite a bit) of money just buying these in the first place. So to anyone looking for the best starting point although somewhat pricey (100$ + - depending), it'll probably save you in the long run if you're the type to "set and forget" tubes, as opposed to a rolling fanatic.
If you're in it for the game, to roll tubes and just have a marry old time doing so, then start with whatever you fancy.
But if you want to spend once, and be happy with the fact that it probably doesn't get much better for a reasonable amount; then these should be it.

Obviously this is my glaringly subjective opinion, and must be understood as such. But to me this is going to be "endgame" for this amp. Simple as that.
Also worth mentioning is that this is paired with Hifiman Sundara balanced in my case, and obviously YMMV as far as your taste in sound signature. 

Compared to the TA-26 This is now a in a kind of strange place, as it sounds more detailed and "cleaner", however i guess it can be percieved as bright in comparison. The TA-20 still has that tubey "space, glow and glare" which is so fascinating. I guess the TA-20 with these tubes sound more "high end"?
It's hard to describe really, but it's just a little more dynamic than with any of the other tubes i've tried with it, that includes the Mullard 12AT7's, which are a bargain buy for this amp in my opinion (about 50$ or so) and a great pairing as well.

Again; my opinion/experience with my setup and my points of reference. But i now have quite a few spare pairs of 12AU7's ..


----------



## Audiophile PT

PetFju said:


> @Audiophile PT
> 
> On this note; I just picked up my Philips Miniwatt E180CC SQ tubes (https://www.ebay.com/itm/133642391945?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649) 12AT7 equivalents to be used in my TA-20.
> First impression (probably no surprise here..) is that i could have just not bothered buying any of the other tubes i have for this amp.
> ...



Thanks for the info @PetFju 
I'm looking for a set of TA-20 Tubes that could smooth the accentuated treble signature of the Meze Liric.
For this particular purpose perhaps those Philips are not enough.
Could you please give me some more insight about the difference between the Mullard's and the Philips.
Thanks.


----------



## PetFju

Audiophile PT said:


> Thanks for the info @PetFju
> I'm looking for a set of TA-20 Tubes that could smooth the accentuated treble signature of the Meze Liric.
> For this particular purpose perhaps those Philips are not enough.
> Could you please give me some more insight about the difference between the Mullard's and the Philips.
> Thanks.


I see. If you want tubes that will shave off some highs you might want to look into some version of 12AU7 Mullard NOS tubes. Exactly which ones i am not sure of as there are a few different versions with different plates, getters and pins, and i am not well versed in them, but there is much info to gain by a simple google search on the topic. 
That said the Mullard 12AT7's i refer to in my previous post are more similar to the E180CC tubes, and as such are considered more detailed and "clear" sounding. If your goal is to shave off some highs you want something different. Someone else will have to chime in here, as i have little experience with Mullard 12AU7's. 

BTW; did you look into some simple EQ'ing for that purpose? I mean with tubes it could be a bit "hit or miss", but with eq you can hone in on your target sound a bit more easily and get exactly what you're after. 
Anyways, just a thought there. I use a RME adi-2 dac with a very good built in digital eq option, which is great if needed. Or one can use Schiit Lokius (?) which i believe is an analog eq, or PEACE software if you want to do it in the digital pc-realm.


----------



## hmscott (Jan 27, 2022)

Yup, the E180CC of various makes/factories/years are "end game" for the TA-20 in many ways, but give it some time as you may find as you get more rounded tubes for the TA-26 that the E180CC's are a bit sharp/bright/edgy, or not, it all depends on your own personal preference.  One persons perfect tube choice may not be yours.

Also headphones play a big role in what we hear from our tubes.  The Sennheiser's roll off the High's, so you may not be hearing the "sharp high's" I was hearing on the TA-26 stock tubes I was hearing through the Hifiman Ananda and sensitive IEM's with treble extension.  On those the sharpness was quite annoying, that is why I moved to the Sennheiser HD660s's - I could still tell it was sharp, but it wasn't as annoying.  When the GE 6AS7G Straight wall tubes arrived the sharpness slightly reduced, but I stayed with the HD660s until the first Sylvania VT-231 arrived, and the sharpness was completely gone.  Now I'm listening to sensitive IEM's on the TA-26, and they sound great!

@Audiophile PT - There are more rounded tubes for the TA-20, like the Tungsram 12AU7 "Black Glass" - those were "end game" for me, found after my previous "end game" tubes, the 6201 Sylvania's, and after both of those the Brimar 6060's (12AT7) were yet another notch up further in the "end game" territory.

I found the Mullard's of the 50's/60's to be not as sharp as the E180CC Mullard, while not being as dynamic - yet at the time I was enjoying them, before the E180CC - those 12AT7/M8162/CV4024 Milspec Mullards of the 50's were also "end game" tubes.   Are we seeing a pattern here?

But, I do agree with @PetFju - a TA-20 owner could save money overall by simply jumping the line of progression many of us have traveled right to a pair of 12AT7 / ECC81 / E180CC, or E80CC tubes made in Heerlen Holland, or Mitcham England, as a first upgrade pair, and be quite happy for a long time, but there will always be that itch to find something better.  How does one know those are the "best" for you without having heard the progression of subsequently better and better tubes along the way?

There are E180CC's that a pair will cost well under $100, if you keep a vigil eye for good prices / sales.  And, if you put those in your cart - a bunch / all of the available options - and wait patiently, likely as not some seller eager to meet their monthly payments will Make an Offer with a discount for 10%/20% even 50% off!

If you look back at my posts here on head-fi - search for TA-20 by hmscott - and on ASR, same hmscott username, I have posted a number of TA-20 tube feedback for my own purchases, and I also posted some of that early info as well... I'll get around to posting it here too, but a simple search on those 2 sites should find what I have posted so far. 

*Update:* I've been watching a Movie on DVD with Cyberlink PowerDVD and it has that TrueTheater Surround, set to Living Room + Full Dynamic Range , and moving from the TA-20 with Mullard '68 M8162 Copper Posts Mitchem Factory, which sounds awesome, plugging into the TA-26 with GE 6AS7G Straight Wall Tubes + Sylvania 6SN7GTA Chrome Top Tall Boy's, and Wow!  There's a huge increase in space and dynamics!  No contest the TA-26 is much more involving in this particular sound track.

*Update:*  I switched to the E180CC Mullard Heerlen Holland tubes, and Wow again!, the jump up from the Mullard Mitchem M8162's is clear, but still not as wide dynamic and deep as the TA-26 with the same GE/Sylvania tubes.

Also, a neat trick I finally figured out on the TA-20!  The black metal guard tube cages can fit *over* the tips of the E180CC's!  That's right, the cage top is *Hollow* at the tube apex, and the tips of the E180CC tubes fit right up into the guard, nice.


----------



## cirodts

i have a sennheiser hd 650 "300 hom" new version with silver drivers, what do you recommend between a ta-20 and a ta-26? and why?


----------



## hmscott (Feb 27, 2022)

cirodts said:


> i have a sennheiser hd 650 "300 hom" new version with silver drivers, what do you recommend between a ta-20 and a ta-26? and why?


Well, I haven't used an HD650 nor a 300 ohm headphone on the TA-20 nor TA-26, so I would only be sharing what I have heard from others experiences with the HD600/HD650 300 ohm headphones on Tube and Tube/Hybrid amplifiers.

In my experience the TA-26 in general does better than the TA-20 with higher impedance headphones, my 600 ohm Beyerdynamic headphones sound much better on the TA-26 vs TA-20, but I had no problems enjoying my Beyerdynamic 600 ohm headphones on the TA-20 before I got the TA-26.

I do enjoy my HD660s 120 ohm headphones on both the TA-20 and TA-26 with both having installed each the best tubes I've found so far.  The TA-26 edges out the TA-20 only so much, but going back to the TA-20 I have no problem listening there for hours.

I will say that there are also definite differences between the Tube/SS sound vs Tube only sound, and it isn't so much that one is better than the other, as the characteristics of both the TA-20 and TA-26 are engaging to me.  Neither are perfect, but both are engaging and enjoyable to listen with my headphones.

I think after hearing both, you'll probably want both, as I am finding too - I can see there will be times I'll want to switch back to the TA-20 to change up the sound characteristics - and then back to the TA-26;  as our ears can get too much of a good thing and all that goes with it.

I have had the 300 ohm Sennheisers on my radar for a long time, but I've got enough headphones for now, as I need more tubes more than more headphones...


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## PetFju (Jan 29, 2022)

hmscott said:


> In my experience the TA-26 in general does better than the TA-20 with higher impedance headphones, my 600 ohm Beyerdynamic headphones sound much better on the TA-26 vs TA-20, but I had no problems enjoying my Beyerdynamic 600 ohm headphones on the TA-20 before I got the TA-26.
> 
> I do enjoy my HD660s 150 ohm headphones on both the TA-20 and TA-26 with both having installed each the best tubes I've found so far.  The TA-26 edges out the TA-20 only so much, but going back to the TA-20 I have no problem listening there for hours.
> 
> ...



I couldn't agree more. I've spent the majority of my time since purchase using my TA-26 with a pair of HD-58X which are 150 ohms. The TA-26 has zero issues running them to what i believe is their limits and far beyond as far as sheer volume goes.
The last day or two i've spent some time using the Beyer DT880 600ohms as well, and the same goes for those really. Depending on what output gain i push from my dac i either end at max 3 o'clock or 1 o'clock. So no issues. And it drives them with control and plenty of dynamic headroom for my listening levels. Way better than the TA-20 does for the Dt880.
The only other amp i have that come close to the TA-26 is the Atrox V2 (solid state), which outputs approximately 500mw (2x500mw single ended according to specs) at 600 ohms, and 20w at 8ohms. You could basically run a pair of speakers with that thing, so that should tell you something.
Anyways; Great amps, both the TA-26 and the TA-20. Btw i tried running my Sundaras with the TA-26. That was a complete folly, just killed the dynamics of the planars completely, even at full tilt. So that was a futile exercise. So the stated 60-600 ohms load suggestion from Xduoo should at least be kept in mind when pulling the trigger on the TA-26. The TA-20 on the Sundaras on the other hand; To say that they are a superb match would be an understatement


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## kibot (Jan 30, 2022)

PetFju said:


> I couldn't agree more. I've spent the majority of my time since purchase using my TA-26 with a pair of HD-58X which are 150 ohms. The TA-26 has zero issues running them to what i believe is their limits and far beyond as far as sheer volume goes.
> The last day or two i've spent some time using the Beyer DT880 600ohms as well, and the same goes for those really. Depending on what output gain i push from my dac i either end at max 3 o'clock or 1 o'clock. So no issues. And it drives them with control and plenty of dynamic headroom for my listening levels. Way better than the TA-20 does for the Dt880.
> The only other amp i have that come close to the TA-26 is the Atrox V2 (solid state), which outputs approximately 500mw (2x500mw single ended according to specs) at 600 ohms, and 20w at 8ohms. You could basically run a pair of speakers with that thing, so that should tell you something.
> Anyways; Great amps, both the TA-26 and the TA-20. Btw i tried running my Sundaras with the TA-26. That was a complete folly, just killed the dynamics of the planars completely, even at full tilt. So that was a futile exercise. So the stated 60-600 ohms load suggestion from Xduoo should at least be kept in mind when pulling the trigger on the TA-26. The TA-20 on the Sundaras on the other hand; To say that they are a superb match would be an understatement


Privet! ✌
What do you mean about   "That was a complete folly, just killed the dynamics of the planars completely, even at full tilt" ? 
When i used TA 26 with Takstar HF580 planars  thats was very dynamic,but with some distortions i high volume (i think that was cuz of broken transformer )
So i will wait my TA 26 and will try it again with HF580 😉


----------



## PetFju

kibot said:


> Privet! ✌
> What do you mean about   "That was a complete folly, just killed the dynamics of the planars completely, even at full tilt" ?
> When i used TA 26 with Takstar HF580 planars  thats was very dynamic,but with some distortions i high volume (i think that was cuz of broken transformer )
> So i will wait my TA 26 and will try it again with HF580 😉


Sorry if i was unclear  What that means is simply that the Sundaras didn't sound right, or dynamic, even when the TA-26 was at full volume output. It did get loud, but at one point it was like the TA-26 simply ran out of power, and it didn't get any louder, even when turning the volume wheel. Also there was just lacklustre bass and bad dynamics.
Btw; all planars are different, so "your miles may vary", and it may well be that the Takstar you mention will work just fine  For your sake i hope they fare better than the Sundaras!


----------



## cirodts

PetFju said:


> Sorry if i was unclear  What that means is simply that the Sundaras didn't sound right, or dynamic, even when the TA-26 was at full volume output. It did get loud, but at one point it was like the TA-26 simply ran out of power, and it didn't get any louder, even when turning the volume wheel. Also there was just lacklustre bass and bad dynamics.
> Btw; all planars are different, so "your miles may vary", and it may well be that the Takstar you mention will work just fine  For your sake i hope they fare better than the Sundaras!


I have never understood why there is so much fuss for the sundara, it has a thin sound and is often too bright and it is very difficult to pair it with an amplifier that makes it sound good.


----------



## kibot

PetFju said:


> Sorry if i was unclear  What that means is simply that the Sundaras didn't sound right, or dynamic, even when the TA-26 was at full volume output. It did get loud, but at one point it was like the TA-26 simply ran out of power, and it didn't get any louder, even when turning the volume wheel. Also there was just lacklustre bass and bad dynamics.
> Btw; all planars are different, so "your miles may vary", and it may well be that the Takstar you mention will work just fine  For your sake i hope they fare better than the Sundaras!


ah i understand now great thanx!!


----------



## PetFju

cirodts said:


> I have never understood why there is so much fuss for the sundara, it has a thin sound and is often too bright and it is very difficult to pair it with an amplifier that makes it sound good.


That is your opinion. There are many like it, but that one is yours 
Anyways, i guess it depends on many factors whether you like them or not. They are not in any way, shape or form the be all and end all of headphones, but for me they have a place in my setup. They aren't the ones i use the most, or least. 
They are quite neutral, but thin? That is not my experience. Well, that is to say that with the right pairing of source and amp they sound great with a lot of music, i'll even go as far as to say most music. At least my pair, with my gear. But i will end this post like i started it; That's my opinion. There are many like it, but that one is mine. Cheers


----------



## cirodts

PetFju said:


> That is your opinion. There are many like it, but that one is yours
> Anyways, i guess it depends on many factors whether you like them or not. They are not in any way, shape or form the be all and end all of headphones, but for me they have a place in my setup. They aren't the ones i use the most, or least.
> They are quite neutral, but thin? That is not my experience. Well, that is to say that with the right pairing of source and amp they sound great with a lot of music, i'll even go as far as to say most music. At least my pair, with my gear. But i will end this post like i started it; That's my opinion. There are many like it, but that one is mine. Cheers


yes, in fact, it is a simple impression of mine, being extremely neutral the sundara never gave me that sense of fullness of the instrument I was looking for despite having combined it with different amps.


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## PetFju (Jan 30, 2022)

cirodts said:


> yes, in fact, it is a simple impression of mine, being extremely neutral the sundara never gave me that sense of fullness of the instrument I was looking for despite having combined it with different amps.


Gotcha. Sorry to hear that, as i find it to be quite a good value, as many others have concluded before me. However, i see how one could come to the same conclusion as you.
It's the same way with speakers for me. I have had quite expensive hifi-speakers, which were great neutral and linear sounding. However, i always seem to have come back to Klipsch (examples of Klipsch's i've owned are RF-7's, RF-5's and Cornwall 3's, Heresy 3's) who for some reason just sound more musical, and pleases me more. They make my feet move, and just engage me in a different way than a lot of "hifi" speakers do (did).
The most engaging and fun setup i've ever owned was a McIntosh MA8000 integrated amp running Klipsch Cornwall 3's split at the bottom at 80hz to a pair of Ken Kreisel subs. Not my most expensive setup, or even close to most hifi "correct", but by far the most enjoyable and as such most utilized.
Just goes to show how things both change (now i enjoy the sundaras..lol) and are quite subjective.
There are no "right answers", and as long as we're enjoying our music all is well in the world as far as i am concerned 
Edit: Sorry for the OT btw


----------



## cirodts

PetFju said:


> Gotcha. Sorry to hear that, as i find it to be quite a good value, as many others have concluded before me. However, i see how one could come to the same conclusion as you.
> It's the same way with speakers for me. I have had quite expensive hifi-speakers, which were great neutral and linear sounding. However, i always seem to have come back to Klipsch (examples of Klipsch's i've owned are RF-7's, RF-5's and Cornwall 3's, Heresy 3's) who for some reason just sound more musical, and pleases me more. They make my feet move, and just engage me in a different way than a lot of "hifi" speakers do (did).
> The most engaging and fun setup i've ever owned was a McIntosh MA8000 integrated amp running Klipsch Cornwall 3's split at the bottom at 80hz to a pair of Ken Kreisel subs. Not my most expensive setup, or even close to most hifi "correct", but by far the most enjoyable and as such most utilized.
> Just goes to show how things both change (now i enjoy the sundaras..lol) and are quite subjective.
> ...


I understand you ... I also have klipsch.


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## hmscott (Jan 30, 2022)

PetFju said:


> Sorry if i was unclear  What that means is simply that the Sundaras didn't sound right, or dynamic, even when the TA-26 was at full volume output. It did get loud, but at one point it was like the TA-26 simply ran out of power, and it didn't get any louder, even when turning the volume wheel. Also there was just lacklustre bass and bad dynamics.
> Btw; all planars are different, so "your miles may vary", and it may well be that the Takstar you mention will work just fine  For your sake i hope they fare better than the Sundaras!





cirodts said:


> I have never understood why there is so much fuss for the sundara, it has a thin sound and is often too bright and it is very difficult to pair it with an amplifier that makes it sound good.





kibot said:


> ah i understand now great thanx!!


Guys, that is why I bought the TA-20 first, as my favorite headphones are the Hifiman Ananda and Hifiman HE6SE V2, which both respond best to amplifiers that can drive low impedance headphones.

This is also why I suggest having both the TA-20 (or TA-30) + TA-26 works out great as between the two they both cover the range of headphones most of us have, with enough power to drive them to enjoyable levels.

The TA-20 with SS output excels in driving low impedance headphones with enough power to light up the Hifiman HE6SE V2 to enjoyable levels.  The HE6SE V2 really needs 2w-5w to bring the HE6SE V2 to full potential.  And, some think it is more like 7w-14w 

The TA-26 really does help my Sennheiser and Beyerdynamic headphones blossom furthering the enjoyment they brought me on the TA-20.  The full Tube sound of the TA-26 really does bring the dynamic and more realiistic sound stage for me for many recordings, and especially with SFX Audio Movies!  Even with only 2.0 sound the movie Theater and Livingroom settings in Cyberlink's PowerDVD audio options sounds more real than on the TA-20 - or other SS amps.

I haven't heard the Sundara yet, but I enjoy my Amanda on the TA-20 very much.


----------



## pattont

hmscott said:


> Guys, that is why I bought the TA-20 first, as my favorite headphones are the Hifiman Ananda and Hifiman HE6SE V2, which both respond best to amplifiers that can drive low impedance headphones.
> 
> This is also why I suggest having both the TA-20 (or TA-30) + TA-26 works out great as between the two they both cover the range of headphones most of us have, with enough power to drive them to enjoyable levels.
> 
> ...


Ty for posting this. I was looking at the TA-20 vs TA-26


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## hmscott (Feb 4, 2022)

pattont said:


> Ty for posting this. I was looking at the TA-20 vs TA-26


I have a few posts here on head-fi from the last month with TA-26 vs. TA-20 comments.

Do you have any specific questions we can answer about either the TA-26 or the TA-20?

Which one of them are you leaning toward?, the TA-20 balanced?, or TA-30 unbalanced?, or the TA-26 unbalanced? - with the "Tubiest" sound?


----------



## PetFju

Just a quick little update on a slow friday night about the TA-26, which i've owned for a little while now.
I recieved my 6SN7GT JAN GE BLACK PLATE (Canadian made) and have been playing it for about 12 hours now. I have to say, it was a very good investment, and luckily it paid off as i hoped. This beats out the 6SN7GT RCA tube that was in before it by miles. Stronger sound, cleaner and quite a bit more open soundstage. I can easily recommend this tube for the TA-26.
To put it in words many might understand; The TA-26 with this tube gives the Sennheiser HD58X an actual soundstage and some space. Very very good in my opinion. Try Anything by Chris Jones, Allan Taylor or the like and just be carried away into the music.. The TA-26 has so far made me very happy for not that high a price!
BTW; have a great weekend


----------



## hmscott

PetFju said:


> Just a quick little update on a slow friday night about the TA-26, which i've owned for a little while now.
> I recieved my 6SN7GT JAN GE BLACK PLATE (Canadian made) and have been playing it for about 12 hours now. I have to say, it was a very good investment, and luckily it paid off as i hoped. This beats out the 6SN7GT RCA tube that was in before it by miles. Stronger sound, cleaner and quite a bit more open soundstage. I can easily recommend this tube for the TA-26.
> To put it in words many might understand; The TA-26 with this tube gives the Sennheiser HD58X an actual soundstage and some space. Very very good in my opinion. Try Anything by Chris Jones, Allan Taylor or the like and just be carried away into the music.. The TA-26 has so far made me very happy for not that high a price!
> BTW; have a great weekend


Happy Friday


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## hmscott (May 2, 2022)

ocZZ said:


> I've spent just about as much on tubes as the amp itself at this point  also, just retesting the 12AT7 Mullards and E180CC Amperex with the new USB cable, it's clear the Amperex is a better fit. The highs are more rounded (can be too bright on Mullard), the mids are more forward (mids muted and muffled on Mullard), bass is about the same but maybe abit tighter on Mullard but sound stage is really good on the Amperex. I think these are from Harleen according to the item description but not Mullard but Amperex. https://www.ebay.com/itm/185071855549


Hi, how are you?  

I followed through and picked up a "pinched waist" variant of the "PHILIPS/AMPEREX HOLLAND 1960'S E180CC 7062 TUBE" from pauls994 :

NOS NIB PHILIPS HOLLAND PINCHED WAIST D FOIL GETTER E180CC 7062 12AT7 E81CC
https://www.ebay.com/itm/185162828671

...for comparison with the Mullard I'm enjoying now on the TA-20:

180CC 5965 12AV7 NOS Mullard Holland Valve Tubes
https://www.ebay.com/itm/112112339682

pauls994 's own comment on the sound comparison between the Amperex 7062's"

"After listening to various 12AT7 type tubes, I think I finally found the best balance between dynamics, warmth, liquidity, and transparency - the Amperex Holland D Foil getter 7062 E180CC. The pinched waist version is also quite good - having greater warmth and liquid sound, and a bit less of transparency and dynamics."

I'll give the "pinched waist" variant a listen in comparison to the Mullard, and try the non-"Pinched Waist" variant next month.

What are you listening to these days?, are you content with your Amperex 7062?


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## hmscott (Feb 11, 2022)

Guys, I asked Xduoo a while back "Which tubes have you tried and enjoyed on the TA-26?" and here is Xduoo's answer:

"Hi, Scott
At present, we confirm that the model of tube that can be replaced as follow:
6N5P-->6H5C、6AS7、6N13P、6080
6N8P-->6H8C、6SN7、ECC33、5692
*Best Regards*"

Here is my email to Xduoo asking about compatibility of tubes on the TA-26, and what I am thinking about trying:


Spoiler: Click to see...



"Hi!, Happy New Year!! 

I am looking for tubes to upgrade the TA-26 from tube dealer friends on eBay and elsewhere, and one of them asked a question I was wondering... can the TA-26 transformer/power delivery accommodate the 6528a?

I found this posting listing various tube options for the Darkvoice:
https://www.head-fi.org/threads/darkvoice-336i-336se-tuberolling-partii.348833/post-14878993

6528 - equiv to 5998 but very high gain at 9, twice the current load. _*Make sure your amp can handle it*_

I did a little research and on other amplifiers it requires some circuit changes to allow the increase in power, so I wanted to find out from you what you would suggest.

I planned on getting a NIB/NOS 6as7g RCA from the 50's, or a Tungsol/Cetron 6080 to start.  And, a nice Tall Sylvania 6NS7GTA, _*single tubes of each*_, that is what lead me to the discussions from one dealer about the 6528a.

FYI, here are those tubes:

6SN7 GTA SYLVANIA NOS SAME DATE CODE TALL GLASS PLATINUM MATCHED QUAD
https://www.ebay.com/itm/143395297531
TWO MATCHED NEW BOXED BLACK PLATE MIL. QUALITY RCA 6AS7G DUO-TRIODES FOR AUDIO
https://www.ebay.com/itm/154774264096

I've also looked at the new PSVANE 6SN7 options.

Which tubes have you tried and enjoyed? 

Thank you!, Scott"

Unfortunately those nice '52 6AS7G's are only available as a pair, the seller doesn't want to split them and sell singles.  He's relisted it since and the matched pair are still available:
https://www.ebay.com/itm/154819826553


Up till today I've had trouble finding what I really wanted for the 6N5P spot, but I did get a nice GE 6080 that did pick up the Bass, and paired with a couple of 1940's Sylvania 6SN7GT VT-231 and a Tallboy Chrome Top Sylvania 6SN7GTA tube, I've really been enjoying listening to music, vocals, and video/movies.

The Russian 6H5C, 6N13P Svetlana tubes are now shipping and on their way.  The seller was on vacation, and when he came back we discussed another tube, a 1953 Melz 6H8C Metal Base along with a pair of Melz 1578's.  For now I decided on the 1953 Melz to try first and listen to for a while before getting the 1578's.

Working with 12-rocketman has been very educational and fun, I really did appreciate his help and information he shared.  We must have exchanged a few dozen messages, even during his holiday, it was quite pleasant.

The same can be said for all of the sellers I've bought from and had enjoyable discussions, and I might as well share with you the other tubes I haven't mentioned and are on the way right now:

NOS VINTAGE TUNG SOL CETRON 7236 5998 TUBE WOO HEADAMPS PAIRS AVAILABLE - *sounds great!, really punchy, clear, solid bass+vocals+instruments*

6AS7G RCA Headphone Amplifier Tube Made in U.S.A Amplitrex Tested#309008 - *Much different than the 7236, while still wide, clear, it is more "full" sounding*

6N8S / 6SN7 / 1578 MELZ TUBE HOLE PLATE NOS METAL BASE DATE 1953 Lot 1pc.- *It's gonna be a while coming from UA*

CBS JAN CHY 5692 6SN7 VACUUM TUBE SINGLE BLACK PLATE NOS ORIGINAL BOX - *Received, not tried yet...*

1pc 6N8S / 6Н8С ~ 6CC10,6SN7,1578 Double triode NEW. OTK. MILITARY. METAL BASE -*En route from Russia.*

KEN-RAD JAN CKR 6SN7 GT VT-231 1944 LEGENDARY BLACK BEAUTY CHROMED FOIL NIB MINT - *Received, not tried yet...*

And, here is the one I was looking for all along, hopefully I'll get it, but it is a work in progress: *This NIB 50's JAN RCA 6AS7G is the best sounding so far!*
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-16802216

These along with the Russian 6AS7G equivalents should keep me busy for a while 

*Updated each tube listed with status, more later...*


----------



## claud W

1952 and 53 Sylvania JHS 5654 tubes


----------



## Shane D

Still waiting on my MT-602! I want to post here damnit!


----------



## jonathan c

claud W said:


> 1952 and 53 Sylvania JHS 5654 tubes


Does the amplifier body get really warm? Have you tried socket savers / tube risers?


----------



## claud W (Feb 9, 2022)

jonathan c said:


> Does the amplifier body get really warm? Have you tried socket savers / tube risers?


I have been unable to find any 7 pin socket savers. The body of the amp does get warm, but not hot.


----------



## fonkepala

Shane D said:


> Still waiting on my MT-602! I want to post here damnit!


Loads of power, happy with mine. I think you'll most probably like it. Do you plan on swapping tubes right away?


----------



## Shane D

fonkepala said:


> Loads of power, happy with mine. I think you'll most probably like it. Do you plan on swapping tubes right away?


Yes. I ordered (and received) two sets of matched tubes when I ordered the amp:
2 X GE JAN5654W's
2 X 6J1P-EV's 

Still no update on my amp though. Ordered Jan.25th. If I had known that it needed to be shipped from China, I would have made other arrangements. Likely woukd have ordered the MT-604 that was in stock at Amazon.ca


----------



## jonathan c

claud W said:


> I have been unable to find any 7 pin socket savers. The body of the amp does get warm, but not hot.


Have a look if you wish:


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## PetFju (Feb 9, 2022)

I have a question to those of you out there with a TA-20. I just got myself a pair of HifiMan Edition XS, and they replaced my Sundaras on the TA-20 as my "planar setup".
However, i noticed now for the first time that microphonics is REAL real. Even turning the volume wheel makes audible noise from the driver in the headphones. And tapping lightly on the chassis or tubes is just a serious no-go. Is this normal? I have never ever had any issues of this sort nearly this evident before.
Obviously this issue came into my life alongside the Edition XS's, but still. I didn't think that they would be that much more sensitive than any other headphone i've ever tried out on the TA-20.
Any experiences and or opinions on the matter out there?


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## Silver Wolf (Feb 9, 2022)

I have the XS and TA-20, are you hearing this while music is playing or without and just rotating volume knob on the TA-20?

edit: just threw mine on to try out... silent..... tapped on chassis...silent...finger nail tapped tubes...nothing. Mind you these XS do sound very nice on the TA-20 (BAL or SE but then I think power is same on both with this amp) for my tastes.

Wonder if it's a tube, I did get a little something similar from one of my old Brimar tubes but only when I touched it, when just sitting back listening it was all good.


----------



## PetFju

Silver Wolf said:


> I have the XS and TA-20, are you hearing this while music is playing or without and just rotating volume knob on the TA-20?


When music is playing it is inaudible unless the volume is all the way down, and is only audible when i am actually manipulating the amp in one way or another. 
And its no issue when just playing music as the amp is placed on my desk, and on a little "platform" isolated from the desk surface with some rubber dampeners.
Another thing is that it the left channel is more heavily affected then the right (haven't tried swapping the tubes around yet tp see if it "follows" the tube)


----------



## fonkepala

Shane D said:


> Yes. I ordered (and received) two sets of matched tubes when I ordered the amp:
> 2 X GE JAN5654W's
> 2 X 6J1P-EV's
> 
> Still no update on my amp though. Ordered Jan.25th. If I had known that it needed to be shipped from China, I would have made other arrangements. Likely woukd have ordered the MT-604 that was in stock at Amazon.ca


Nice! Here's hoping you get your MT602 soon. And do let us know how it goes with those tubes you've ordered.




jonathan c said:


> Have a look if you wish:


First time I'm getting to know about these. I'm assuming they're to lessen the chances of the vacuum tube sockets being damaged when doing frequent tube-swapping?


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## hmscott (Feb 11, 2022)

PetFju said:


> I have a question to those of you out there with a TA-20. I just got myself a pair of HifiMan Edition XS, and they replaced my Sundaras on the TA-20 as my "planar setup".
> However, i noticed now for the first time that microphonics is REAL real. Even turning the volume wheel makes audible noise from the driver in the headphones. And tapping lightly on the chassis or tubes is just a serious no-go. Is this normal? I have never ever had any issues of this sort nearly this evident before.
> Obviously this issue came into my life alongside the Edition XS's, but still. I didn't think that they would be that much more sensitive than any other headphone i've ever tried out on the TA-20.
> Any experiences and or opinions on the matter out there?


Microphonics are conducted and exacerbated by stiff headphone cables, and Hifiman's Classic "Medical tubing" sheathed cables are one of them 

If your tubes are microphonic you want to find/use soft jacketed cables that won't conduct any vibrations, stiff coverings that can conduct the vibrations will make more noise when moving them around.

I replaced my Hifiman cables with GUCraftsman Silver plated cables for the Ananda and HE6SE V2, and also for my HD660S, HD598cs headphones:
https://www.aliexpress.com/store/3879013
https://hifigo.com/collections/gucraftsman

For my IEM's I use KB Ear 16 Core Silver and 4 core 99% Pure Silver cables.
https://hifigo.com/collections/kbear
https://hifigo.com/products/kb-ear-...th-metal-2pin-mmcx-qdc?variant=31605483667505
https://hifigo.com/products/kbear-4...-with-2pin-qdc-mmc-tfz?variant=32250235322417

That said, most of my tubes aren't microphonic.  I've been told that E180CC Pinched Waste tubes are *all* microphonic, but these weren't - at least on my TA-20 with soft cables:

NOS NIB PHILIPS HOLLAND PINCHED WAIST D FOIL GETTER E180CC 7062 12AT7 E81CC
https://www.ebay.com/itm/185162828671

I might have been lucky with those though... I just tapped on the top of both of them in my TA-20 and I had to hit the top of the tube pretty hard to hear anything.

I'm listening with my Sennheiser HD660S stock cable, which is a nice thick rubber like covering for the 6.35mm to 3.5mm converter, and even plugging in the Zip Cord cable that the long length of the cable is made from - still soft and rubber like covering.

BTW, that pair of PHILIPS HOLLAND PINCHED WAIST D FOIL GETTER E180CC sound phenominal, I mean it was so timely getting them along with this latest selection of tubes for the TA-26, as it put the TA-20 back in the "competition", they provide the most space and air of any previous tubes.
With these the TA-20 is "keeping up" with the TA-26  

Give me a day or two and I'll run through my tubes / cables - including the stock Hifiman cables - to see which are making noisy from physical movement / tapping.

Which make/model of tube is doing this?  Is it both tubes?  Do you have a soft adapter extension you could use to interrupt the vibrations?

I haven't felt the need to get any, but there are "tube rings" made for each tube type, heavy metal and rubber, I don't recall where I saw them last, but those are used to dampen oscillations from bad microphonic tubes.

You could also try putting a soft cable converter like mine is between the headphone cable and amp...


----------



## hmscott (Feb 11, 2022)

fonkepala said:


> First time I'm getting to know about these. I'm assuming they're to lessen the chances of the vacuum tube sockets being damaged when doing frequent tube-swapping?


The TA-20 has recessed tube sockets...which I didn't think about too much, until I tried to use a "socket/tube saver"...  then I thought about it a lot.  

The Socket Saver is Short, too short to get a grip around it when plugged in to the TA-20 recessed socket.  I tried to hold it down so I can pull out only the Tube, instead what comes out varies.  If I am pushing down from the right direction, with the right angle, my forefinger's precisely cut fingernail can lock down the "Socket Saver", briefly - sometimes enough to pull out only the tube.

Perhaps there is some solution I am not thinking of.  And, I did try Stacking Two Socket Savers, but it just looked silly - too tall, and it leaned a bit too, but it did work.

Good luck


----------



## PetFju

hmscott said:


> Microphonics are conducted and exacerbated by stiff headphone cables, and Hifiman's Classic "Medical tubing" sheathed cables are one of them
> 
> If your tubes are microphonic you want to find/use soft jacketed cables that won't conduct any vibrations, stiff coverings that can conduct the vibrations will make more noise when moving them around.


I am using a soft aftermarket cable already, and it doesn't seem to have anything to do with it. 

The tubes are the Philips miniwatt E180CC SQ. So the tubes should be good? They sure sound good anyways. 
Like i said; i can hear it even when turning the volume dial, so i am not sure the tubes are the only issue? However it is only audible with the Hifiman Edition XS, no other headphones. Which makes me think the sensitivity of the headphones are to blame. With that said there would be no noise if the amp was actually quiet. 
Anyways; it's no big deal, as i don't usually hold, bump or in other ways touch my amp when listening to music other than turning the volume dial.

Btw i guess i need another set of tubes now, even if i did have the same type of experience of "keeping the TA-20 in the running" using the E180CC tubes


----------



## hmscott (Feb 11, 2022)

PetFju said:


> I am using a soft aftermarket cable already, and it doesn't seem to have anything to do with it.
> 
> The tubes are the Philips miniwatt E180CC SQ. So the tubes should be good? They sure sound good anyways.
> Like i said; i can hear it even when turning the volume dial, so i am not sure the tubes are the only issue? However it is only audible with the Hifiman Edition XS, no other headphones. Which makes me think the sensitivity of the headphones are to blame. With that said there would be no noise if the amp was actually quiet.
> ...


Yes, the tubes are the only issue.  When I have Microphonic tubes in the TA-20, any physical touch on the TA-20, Volume Dial, and depending on how sensitive the tubes are to vibration, even bumping the table the amp is on will caue the tubes to, make "the noise".

Sorry man, I know it's annoying, but you can work around it and still enjoy the tubes.  Especially if you already stopped the headphone cable from triggering the noise.

If you have a soft cable, then you aren't getting headphone cable induced microphonics - which is great, as that is the worst part of it.  Triggering the Microphonics by simply moving your head - moving the headphone cable - is the worst.  So I'm happy to hear your cable isn't triggering the Microphonics.

For the most part we don't touch the TA-20 after plugging in and setting the volume, and as long as your headphone cable isn't triggering the sound, and you aren't bumping the table where the TA-20 sits, you are ok - until you need to adjust the volume.

That's when I use my Topping D90 MQA DAC Volume control in Preamp mode to adjust the volume of the TA-20, and it's even better using the D90 remote control! 

Can you adjust the output of your DAC into the TA-20?  So you never need to touch the TA-20 except to turn it on / off?

Yeah, well, I have a couple of microphonics tubes, and I still use them from time to time and I can make it work, so you can too. With some practice I've discovered how to find the operating an mode that doesn't trigger the noise.

Also, yes, you need more tubes.  "More tubes" is always the most important part of any audio solution.


----------



## PetFju (Feb 11, 2022)

hmscott said:


> That's when I use my Topping D90 MQA DAC Volume control in Preamp mode, with remote control!
> 
> Can you adjust the output of your DAC into the TA-20?  So you never need to touch the TA-20 except to turn it on / off?



That is actually not a bad idea. I can use the ADI-2 as my volume control. The only issue i see with that is that there might be more noise induced in the amp itself when it is at "full gain" at all times?

BTW; Yes, as long as i leave it alone and don't touch it, it's quiet. Only when i adjust volume or touch it in any other way does it make the noise. 

And yes, MOAR TUBEZ


----------



## hmscott (Feb 11, 2022)

PetFju said:


> That is actually not a bad idea. I can use the ADI-2 as my volume control. The only issue i see with that is that there might be more noise induced in the amp itself when it is at "full gain" at all times?
> 
> BTW; Yes, as long as i leave it alone and don't touch it, it's quiet. Only when i adjust volume or touch it in any other way does it make the noise.
> 
> And yes, MOAR TUBEZ


OMG, please don't put the TA-20 at full gain! Yipe!

Well, it would be "fine", I've tested it a couple of times at 100% when testing new cables - to find the best shielded cable(s), and now I have no noise out of the TA-20 at 100% volume, but it's not necessary to run the TA-20 at 100%, in face you want to run the DAC closest to 100% for the best sound integrity.

Basically, you want to run all the "data source" device chain at 100% volume - ideally the PC (source) + DAC both run at a 100% fixed output voltage into the headphone amp for best signal to noise ratio, and the headphone volume is controlling the level heard in the headphones.

The way I do it is to set the DAC / Source output to 100%, and then find the normal maximum Volume setting on the Headphone AMP where I normally leave it set to listen to music/video, and then use the DAC variable output to lower the volume from "normal", to reduce the sound in the headphones.

This way I am not dropping the DAC output much - maintaining maximum source S/N ratio - and the Headphone AMP is at it's "optimal" Volume setting too.

Of course, we cannot increase the headphone output once we are at 100% on the DAC, so then we'd need to increase the volume on the TA-20... and eventually I found the optimal highest volume setting on the TA-20 that would in concert with the D90 remote control volume output, be satisfactory for hands off volume range control of the TA-20 output.
And yes, MOAR TUBEZ!


----------



## PetFju

@hmscott Ok, i see what you mean now. I thought you meant to use basically use the TA-20 as a "power-amp" and the dac as a "pre". 
But yea, i think i optimized the output volume already, but there is some available adjustment in the DAC as it is atm, so i'll try that to see how it fares. There is also the option to use the windows volume more as well, even though it is sonically inferior. 
I'll try some different things and find what i like the best.


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## hmscott (Feb 11, 2022)

PetFju said:


> @hmscott Ok, i see what you mean now. I thought you meant to use basically use the TA-20 as a "power-amp" and the dac as a "pre".
> But yea, i think i optimized the output volume already, but there is some available adjustment in the DAC as it is atm, so i'll try that to see how it fares. There is also the option to use the windows volume more as well, even though it is sonically inferior.
> I'll try some different things and find what i like the best.


I went looking for tube dampers, and found this review of a bunch of options (at the time the article was written):

Herbie's Tube Damper Comparison
https://herbiesaudiolab.com/pages/herbies-tube-damper-comparison

Herbies Tube Dampers
https://herbiesaudiolab.com/collections/tube-dampers

Perhaps a note to Herbie to let him know what tubes you have and what the characteristics of the noise you are hearing would help him recommend single/double rings per tube, or?  Plus other damping suggestions - Herbie would be the guy to ask, with all those years of experience designing, testing, and marketing real solutions.

This is the first I've seen of this site, never talked with Herbie, but a first read on the situation tells me he would be worth contacting


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## PetFju

hmscott said:


> I went looking for tube dampers, and found this review of a bunch of options (at the time the article was written):
> 
> Herbie's Tube Damper Comparison
> https://herbiesaudiolab.com/pages/herbies-tube-damper-comparison
> ...


I already ordered some Audio research tube dampers from a local retailer (as shipping will be much quicker), but thanks for the tip 
Especially interesting to have the list of different types for posterity (i might try different ones)


----------



## hmscott

PetFju said:


> I already ordered some Audio research tube dampers from a local retailer (as shipping will be much quicker), but thanks for the tip
> Especially interesting to have the list of different types for posterity (i might try different ones)


The customer reviews are interesting too, with photo's of their tube amps + damping solutions.

What is the link to the product(s) you ordered - seller/manufacturer's product pages, both?


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## PetFju (Feb 11, 2022)

https://www.mono.no/audio-research/9633126/audio-research--tube-dampers-pr-stk-2-stk-rør-dempere-anbefales-pr-rør

Don't have the manufacturers link unfortunately

Also, the site is in Norwegian (obviously) as the store is located in Norway.


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## hmscott (Feb 11, 2022)

A thread elsewhere - I haven't even looked here on head-fi yet 

"Best tube dampers that you have used"
https://forum.audiogon.com/discussions/best-tube-dampers-that-you-have-used

Note: I haven't used any of these dampers myself (yet?).


----------



## PetFju

hmscott said:


> A thread elsewhere - I haven't even looked here on head-fi yet
> 
> Best tube dampers that you have used
> https://forum.audiogon.com/discussions/best-tube-dampers-that-you-have-used


Based on this i apparently need to check out Herbies..


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## hmscott (Feb 11, 2022)

PetFju said:


> https://www.mono.no/audio-research/9633126/audio-research--tube-dampers-pr-stk-2-stk-rør-dempere-anbefales-pr-rør
> 
> Don't have the manufacturers link unfortunately


Cool, something like that is what I was thinking of too, large enough + mass to make a difference.  After reading Herbie's discussion though, they may be over doing it a bit, affecting the sound - besides damping the oscillations they might affect the music.  Some are reporting all of the dampers affect the sound, for the worse, reducing the "tubiness".

Hopefully they will stop the distracting tube microphonics, and improve the sound too 


PetFju said:


> Based on this i apparently need to check out Herbies..


Yup, me too. 

Let's share when we've had a chance to test them as we get them.  I will need to find my microphonic tubes again.  I think one pair were the 17mm black plate RCA clear tops...

But, given what people are reporting, it might be worth trying rings out on tubes that aren't microphonic, to see how the rings affect the sound.

More Tube Toys


----------



## albertmuc

A „Xduoo Ta 20“ is coming.  

I have already been instructed to order a pair of matched "Genalex Gold Lion 12AU7/ECC82 Gold Pins".  

If it’s imperative to add another pair of specific tubes to the order, please let me know, so I can do it all in one go…


----------



## jonathan c

albertmuc said:


> A „Xduoo Ta 20“ is coming.
> 
> I have already been instructed to order a pair of matched "Genalex Gold Lion 12AU7/ECC82 Gold Pins".
> 
> If it’s imperative to add another pair of specific tubes to the order, please let me know, so I can do it all in one go…


If you can, order a pair of RFT ECC82. These are _fantastic _12AU7s (especially the ‘foil getter’ version). I have been using these in a Rogue RH-5.


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## PetFju

albertmuc said:


> A „Xduoo Ta 20“ is coming.
> 
> I have already been instructed to order a pair of matched "Genalex Gold Lion 12AU7/ECC82 Gold Pins".
> 
> If it’s imperative to add another pair of specific tubes to the order, please let me know, so I can do it all in one go…


If you have read this thread you would see that a lot of us are settling on a variant of E180CC Tubes, a 12AT7 variant. You should look into tubes of this type at least, and you could get good advice on specific types by reading the last few pages of this thread.


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## albertmuc (Feb 11, 2022)

jonathan c said:


> If you can, order a pair of RFT ECC82. These are _fantastic _12AU7s (especially the ‘foil getter’ version). I have been using these in a Rogue RH-5.





PetFju said:


> If you have read this thread you would see that a lot of us are settling on a variant of E180CC Tubes, a 12AT7 variant. You should look into tubes of this type at least, and you could get good advice on specific types by reading the last few pages of this thread.


The designations of the tubes are all similar, although they actually all look the same, there are small differences somewhere. If there are many indications that the tube corresponds to the one you are looking for, then these are not available as a matched pair. Kind of confusing. On top of that, so many recommendations. I'll order some tubes and then bend the legs until it fits


----------



## jonathan c

albertmuc said:


> The designations of the tubes are all similar, but there are small differences somewhere, although they actually all look the same. If there are many indications that the tube corresponds to the one you are looking for, then these are not available as a matched pair. Kind of confusing. On top of that, so many recommendations. I'll order some tubes and then bend the legs until it fits


The 12AT7 has a gain of 60x: the 12AU7 has a gain of 20x. Filament current is the same. The gain of the 12AT7 may be too much for the TA-20: distortion and noise floor may rise.


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## PetFju (Feb 11, 2022)

albertmuc said:


> The designations of the tubes are all similar, but there are small differences somewhere, although they actually all look the same. If there are many indications that the tube corresponds to the one you are looking for, then these are not available as a matched pair. Kind of confusing. On top of that, so many recommendations. I'll order some tubes and then bend the legs until it fits


Well, the E180CC are just another designation for a variation of the 12AT7 tube, which is physically (not electrically) identical to the 12AU7. Meaning the pins are the same, and the layout/size of the glass tube is similar enough. The TA-20 works just fine with the 12AT7, according to xDuoo themselves.
The 12AT7's and their variations are just fine to use with this amp, and slots right in no mods needed. The electrical differences account for the difference in sound signature to the 12AU7, and in most cases the sound signature of the 12AT7 vs the 12AU7 in this amp is more dynamic, clear and offers a little more "oomph" in most respects.
Obviously YMMV with the specific tubes and some 12AU7's certainly will sound better than some 12AT7's, but in general most people that have tried 12AT7 in the TA-20 seems to have stuck with it.
So take from this what you will, it is simply meant to inform you that there are options out there


----------



## CJG888

jonathan c said:


> If you can, order a pair of RFT ECC82. These are _fantastic _12AU7s (especially the ‘foil getter’ version). I have been using these in a Rogue RH-5.


+1 on the RFTs. I’ve been saying this for years.


----------



## claud W

Received my MT-604 a few days ago. Pulled all the tubes out and installed Sylvania 1952 & 3 JHS 6AK5s. Sounded pretty damn good. Been playing it a little bit until today when it got overly bright. Pulled the Sylvania and installed WE 403Bs . Much better, but I am going to leave this amp on for about 100 hours to burn it and tubes in,


----------



## PetFju

CJG888 said:


> +1 on the RFTs. I’ve been saying this for years.


https://www.ebay.com/itm/265405072714?hash=item3dcb60054a:g:BVAAAOSwf7NhL8nv

Just ordered a pair. We'll see how these fares


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## albertmuc (Feb 12, 2022)

PetFju said:


> https://www.ebay.com/itm/265405072714?hash=item3dcb60054a:g:BVAAAOSwf7NhL8nv
> 
> Just ordered a pair. We'll see how these fares


You don't care about matched tubes...


----------



## jonathan c

PetFju said:


> https://www.ebay.com/itm/265405072714?hash=item3dcb60054a:g:BVAAAOSwf7NhL8nv
> 
> Just ordered a pair. We'll see how these fares


Those are the ones. The seller, delax777mechanics,  is one whom I highly recommend. I have bought on numerous occasions RFTs of different types from him. Great tubes, prompt delivery 👍.


----------



## PetFju

albertmuc said:


> I see you don't care about matched tubes...


In this case; No. The reason for that was that a matched pair was simply unavailable with the foil getters, at least for a sane amount of money. 
Also i have yet to have an audible issue regarding the matter (mached vs unmatched pair) tbh, meaning as long as the tubes are all good, of the same type and NIB+NOS i will not be able to hear anything out of sorts unless one ore both of the tubes are faulty. 
If my equipment cost 10-20 times more i might care, but the differences in this case should be miniscule if any.


----------



## PetFju

jonathan c said:


> Those are the ones. The seller, delax777mechanics,  is one whom I highly recommend. I have bought on numerous occasions RFTs of different types from him. Great tubes, prompt delivery 👍.


Glad to hear it. Like i mentioned above i went for the foil getters rather than matched pair in this instance. I'm excited to see what the hype is about, as i really was determined to stick with my E180CC tubes for the foreseeable future. I find them just about perfect tbh, so it'll take something special to dislodge them from the sockets permanently


----------



## albertmuc (Feb 12, 2022)

PetFju said:


> https://www.ebay.com/itm/265405072714?hash=item3dcb60054a:g:BVAAAOSwf7NhL8nv
> 
> Just ordered a pair. We'll see how these fares


I also ordered out of solidarity 😊


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## jonathan c

PetFju said:


> Glad to hear it. Like i mentioned above i went for the foil getters rather than matched pair in this instance. I'm excited to see what the hype is about, as i really was determined to stick with my E180CC tubes for the foreseeable future. I find them just about perfect tbh, so it'll take something special to dislodge them from the sockets permanently


There is plenty of raving about the RFT foil getters in the Schiit Mjolnir II threads !


----------



## hmscott

Each of you with a TA-20 might want to try the 12AT7/ECC81 out for yourselves.

When plugging in the 12AT7/ECC81 and variants like the 6060, 8162, CV4024, E80CC, E180CC, I've found they all bring a very special sound that in comparison the 12AU7's sound "uninspiring", at least to me and the people that have posted their own thoughts on trying them in their TA-20's.

The 12AX7 has even more gain than the 12AT7, and it indeed sounds "hot" to me in the TA-20, so I've only tried a couple of pair of them, and then that was enough to convince me the magic is in the 12AT7 and variants in the TA-20.

The E180CC's I've plugged in to the TA-20 are really the pinnacle of the best tubey sound in the TA-20, but the Brimar 6060 Yellow T's, Tung-sol Black Glass 12AU7 come close

PHILIPS HOLLAND PINCHED WAIST D FOIL GETTER E180CC <= Latest, competed well with the TA-26, until the latest combination of tubes for the TA-26, see below
Matched Pair E180CC NOS Mullard Holland Valve Tubes
E180CC 5965 12AV7 NOS Mullard Holland Valve Tubes

The TA-26 with stock tubes right out of the box was far more tubey sounding to me than the best 12AT7 in the TA-20, and the TA-26 has only gotten better with 1940's/50's/60's tube changes.  Earlier I posted my recent tubes for the TA-26, and right now these 2 pairings are really amazing, and only the newest E180CC Amperex Pinched Waist tubes come close, but not quite enough.  These tube combinations on the TA-26 really are thrilling:

Jan RCA 6AS7G + KEN-RAD JAN CKR 6SN7 GT VT-231 1944 LEGENDARY BLACK BEAUTY CHROMED FOIL

And it really is a toss-up whether that KEN-RAD VT-231 or this CBS JAN CHY 5692 are "better", they both sound different with the JAN RCA 6AS7G, both thrilling and compelling, I was mesmerized with the JAN 5692+JAN 6AS7G.

Sorry about that, we were talking about the TA-20? 

I've written a lot here on the TA-20 tubes and Xduoo interactions, and I will continue to post about new TA-20 tubes as I find gems like this one, which shows I haven't completely given up on the 12AU7 in the TA-20, these are supposed to be comparable to Telefunken Smooth Plate tubes.  As I've tried to find affordable NIB Telefunken tubes and find them far too pricey, I am hoping these come close:

4 Strong Matched NOS IC Ei Yugoslavia Long SMOOTH Gray Plate 12AU7 / ECC82 Tubes

It has been very enjoyable slowly stepping through the 12AU7's until I found enough people recommending 12AT7 as sounding so much better in the TA-20, that I asked Xduoo if 12AT7/12AX7's were also supported in the TA-20:


Spoiler: Xduoo's short reply relayed through Hifigo



is it possible to substitute the 12AU7 with 12AT7 or 12AX7 :* Xdoo reply yes no problem. <= for TA-20, and others have inquired Xduoo with same answer*


And, I've been running nothing but 12AT7 variants for the better part of a year with no apparent problems.  No smoke or any increase in heat output of the TA-20 or the running tubes.

Also, the difference in "gain" is handled / balanced by the Xduoo discrete transistor SS output stage.  On the TA-20 a difference in "gain" between the 12AU7 and the 12AT7/12AX7 does not affect - increase- the TA-20 volume.  The Volume Dial setting on the TA-20 remains the same for the same output no matter which 12xx7 tube is installed.

I have my eyes out for other desireable 12AU7 tubes, but for right now I am mostly focusing on the TA-26


----------



## hmscott (Feb 27, 2022)

jonathan c said:


> If you can, order a pair of RFT ECC82. These are _fantastic _12AU7s (especially the ‘foil getter’ version). I have been using these in a Rogue RH-5.





CJG888 said:


> +1 on the RFTs. I’ve been saying this for years.





PetFju said:


> https://www.ebay.com/itm/265405072714?hash=item3dcb60054a:g:BVAAAOSwf7NhL8nv
> Just ordered a pair. We'll see how these fares





jonathan c said:


> There is plenty of raving about the RFT foil getters in the Schiit Mjolnir II threads !





PetFju said:


> In this case; No. The reason for that was that a matched pair was simply unavailable with the foil getters, at least for a sane amount of money.
> Also i have yet to have an audible issue regarding the matter (mached vs unmatched pair) tbh, meaning as long as the tubes are all good, of the same type and NIB+NOS i will not be able to hear anything out of sorts unless one ore both of the tubes are faulty.
> If my equipment cost 10-20 times more i might care, but the differences in this case should be miniscule if any.


The only consideration I've found is that in general the tube dealers match the best measuring tubes and sell the odd ends as singles.  I've requested many times of sellers to test and provide only 100%+/100%+ tubes, "NOS"/"NIB" included.  Anything less than New is Used - with who knows how many hours on the tube(s).  Recently I got lucky with that Jan RCA 6AS7G "NIB", as he couldn't do more than Emission tests with his tester, fortunately it turned out to be a great tube.

Starting out I was looking for inexpensive Used tubes with 85%/85% or greater Lifetime measurements for the TA-20, and most were fine tubes - already broken in - but when I finally branched out from headphones to IEM's I quickly found most of those tubes HISSED like crazy, oddly I didn't hear it in the HD598cs at the time.

For that  RFT 12AU7 with Foil Getter, they will simply pull them as "unused open box" from a production case, so our result is random and untested, but "New in Box" for a great low price.

And, the RFT 12AU7 have always looked interesting, and I'm looking forward to trying the  Ukraine RFT ECC82 12AU7 Tube on my next Tube buying hunt.

At $20/tube I'll probably get 4 of those RFT tubes, 2 pair, with tubes as backup, as a hedge against getting 1 bad one out of a single pair.  It takes so long to get packages from Ukraine/Russia these days, 6-8 weeks or more, it would be sad if I ordered 1 tube/pair of anything, and a single tube ended up bad, so I'd have to order again and wait another 6-8 weeks for a replacement tube.

The Russian tubes I've bought so far - for the TA-26 - have only been from 2 sellers, but both sellers came back with the same response, they don't test tubes, they sell new tubes direct from manufacturers case, you get what they pull from the box, untested. 12-rocketman also has some Melz 1578 pairs for $350, very desireable variation, with sonic differences from the regular 6N8S, too expensive for me 

6N13S / 6AS7G / ECC230 TUBE SVETLANA Double Triode NOS DATE 1960`s USSR Lot 1pc. - Estimated delivery Fri, Feb 18 - Mon, Mar 7
6N13S /6AS7G /ECC230 /6N5S TUBE SVETLANA TRIODE NOS IN BOX OTK lot 1pc. or more - Estimated delivery Fri, Feb 18 - Mon, Mar 7
6N5S / 6N13S / 6AS7G / ECC230 SVETLANA TUBE NOS OTK USSR RARE 1950`s lot 1pc. - Estimated delivery Fri, Feb 18 - Mon, Mar 7
6N13S / 6AS7G / ECC230 SVETLANA TUBE Double Triode NOS OTK USSR Lot 1pc. - Estimated delivery Fri, Feb 18 - Mon, Mar 7
1pc 6N8S / 6Н8С ~ 6CC10,6SN7,1578 Double triode NEW. OTK. MILITARY. METAL BASE - Estimated delivery Mon, Mar 7 - Fri, Apr 1

This is from a different seller purchased recently, hopefully they will arrive close to the estimate:
6N8S / 6SN7 / 1578 MELZ TUBE HOLE PLATE NOS METAL BASE DATE 1953 Lot 1pc. - Estimated delivery Wed, Mar 16 - Wed, Mar 30

With the prices so low I was able to order a spread of decades, and multiples of the 6AS7G variants, but none are tested or matched - for the TA-26 there are 2 different tubes, so there is no need for a "matched pair".

Once I got approval from Xduoo for using 12AT7/12AX7 tubes in the TA-20, those 4 Strong Matched NOS IC Ei Yugoslavia Long SMOOTH Gray Plate 12AU7 are the first 12AU7's I've invested in since.  Also available from:


Spoiler: Also listed on Reverb from a different seller



https://reverb.com/item/619810-ei-y...te-preamp-tubes-built-on-telefunken-equipment
About This Listing
WE ARE OFFERING SINGLE VINTAGE 70'S EI YUGOSLAVIA BRANDED INTL SERVICEMASTER 12AU7A ECC 82 SMOOTH PLATE PREAMP TUBES. THESE WERE BUILT ON TELEFUNKEN MANUFACTURING EQUIPMENT IN THE 70'S. THEY HAVE SUPERB BUILD QUALITIES WITH HEAVY GLASS, LONG 17MM SMOOTH PLATES, HALO GETTERS AND PROVIDE THAT GREAT FLASH WHEN ENERGIZED. THE MUSICAL QUALITIES OF THESE TUBES ARE FAR SUPERIOR TO ANY CURRENT PRODUCTION TUBES AND RIVAL SOME OF THE BEST 12AU7 VARIANTS EVER MADE. PRICING IS PER SINGLE TUBE BUT WE CAN MATCH PAIRS OR QUADS AT NO ADDITIONAL CHARGE.

FYI, I haven't bought anything on Reverb, or from this seller...but I have purchased a dozen times from desireme1979 and every time I've felt well treated and she's a tough but fair bargainer that has come through for me so many times when I've requested her to find specific tubes she isn't currently listing on eBay, and again with these IC Ei 12AU7's.  Costing a bit more from her, but given her excellent service, I don't mind paying a bit more than the lowest price


Those TA-26 tubes are about 2x-3x the cost per tube of the TA-20 options I've purchased, about $50/tube for the best sounding 12AT7 variants and more like $150+/tube on average for the 6SN7 and $70/tube for the 6AS7G, but it has been worth it for the thrilling sound.  Those average prices can be a lot higher, there are a lot of overpriced tubes out there, the most sought after being the main targets for excess pricing.

The Russian 6AS7G and 6SN7 variants are so inexpensive, I'm hoping what I've heard about pairing a 6N13S/6N5S with the Shuguang Natural Sound Series CV181-T or 6N8S is claimed to be end game for some on the Darkvoice 336E, perhaps it will be the same on the TA-26 .

I really need to prioritize getting a Sennheiser HD600 and HD650 with 300 ohm impedance, starting with the HD600. My HD660s 150 ohm impedance headphone sounds awesome on the TA-26 and TA-20, but on the TA-26 it is possible that a 300 ohm impedance might sound better, like my Beyerdynamic DT990/DT880 600 ohm impedance does compared to the 16ohm and 250 ohm Beyerdynamic DT-770/DT880's. It is time for a new pair of 300 ohm headphones for the TA-26.


----------



## jonathan c

XDUOO TA-20:  Is it fully balanced internally (i.e. between input and output) or does it only ‘feature’ balanced sockets? I cannot tell from the ‘xduoo.net’ description.


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## hmscott (Feb 13, 2022)

jonathan c said:


> XDUOO TA-20:  Is it fully balanced internally (i.e. between input and output) or does it only ‘feature’ balanced sockets? I cannot tell from the ‘xduoo.net’ description.


Good question, fortunately Xduoo shared the signal architecture:

"Hi, Scott
1. U1, U2 is the OPA which convert the single-ended signal from RCA into a balanced signal. If it is a balanced input, the signal does not pass through U1 and U2.
The circuit architecture diagram is as follows:




Although the diagram doesn't show it, there are 2 AUX IN's, AUX1 and AUX2, all 3 positions are run through by pushing in the Volume control.  There are 3 Blue indicator lights under the Balanced Headphone Socket on the bottom right that show which position the input switch is in right now.

I use both AUX IN's, with 1 coming in from a Docked Nintendo Switch, and one on a 2M long input cable I can use to plug in portable radio's and other devices with a 3.5mm Audio Line output.  I've specified and ordered custom Worlds Best Cables using thinner Mogami 2893 Quad Shielded cable.

This all came about when I asked Xduoo about swapping in better OPA's, and once Xduoo explained the design it became clear there might not be better OPA's for this application, and the Balanaced Input doesn't pass through any OPA at all.

So yes, the TA-20 is a Fully Balanced design from input to output


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## ostewart (Feb 13, 2022)

I've been spending some time with the TA-26 and really like it - https://www.head-fi.org/showcase/xduoo-ta-26.25647/reviews#review-27937

I've got some RCA (Hewlett Packard branded) 6AS7G tubes on the way, paired with a Sylvania 6SN7GT (Rogers branded) tube - really easy to tube roll and a lovely little OTL amp for the price.


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## PetFju (Feb 15, 2022)

I had an interesting experience with my TA-26 (again). I hooked up my AKG K712 Pro's, which are quite nice on tube amps according to a lot of people. This resulted in an unfortunate experience. They basically sounded the same way as Sundaras on this amp; Flat, tinny, and bass-shy. And when turning up the volume there was quite audible distortion.
Now i have to say i didn't expect this, as the 712's are dynamic driver, 62 ohm headphones. And as such should be within the specs suited for this amp. That really sucked, i have to admit.
For now i am still stuck on my Atrox V2 for these cans, so maybe i should run the TA-26 as a pre for that to get some tube magic out of it (even though they sound excellent on the Atrox).
Anyways; anyone know if the pre out of the TA-26 is decoupled from the headphone jack out? Meaning; will the headphones have to be disconnected to use the pre out?

EDIT; BTW another question..I have in my budget for the next month to get either a Sennheiser HD 650 or a pair of HD 660S to use with the TA-26. Any experiences with any of these on the TA-26 out there?


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## hmscott (Feb 16, 2022)

My eBay order for 4 Russian 6H13S (6N5P) 6AS7G Svetlana tubes + 1953 Melz 6N8S (+ 1 free 6H13S tube) have arrived, and it only took 10 days shipping from Russia to get to Northern California.
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-16819953

I'll try them in my TA-26 in reverse age order paired with a 1957 RCA JAN 5962 Brown Base tube that I've been enjoying paired with a 1950 JAN RCA 6AS7G.  Then I'll swap the 5962 with the 1953 Melz 6N8S.


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## hmscott (Feb 27, 2022)

PetFju said:


> I had an interesting experience with my TA-26 (again). I hooked up my AKG K712 Pro's, which are quite nice on tube amps according to a lot of people. This resulted in an unfortunate experience. They basically sounded the same way as Sundaras on this amp; Flat, tinny, and bass-shy. And when turning up the volume there was quite audible distortion.
> Now i have to say i didn't expect this, as the 712's are dynamic driver, 62 ohm headphones. And as such should be within the specs suited for this amp. That really sucked, i have to admit.
> For now i am still stuck on my Atrox V2 for these cans, so maybe i should run the TA-26 as a pre for that to get some tube magic out of it (even though they sound excellent on the Atrox).
> Anyways; anyone know if the pre out of the TA-26 is decoupled from the headphone jack out? Meaning; will the headphones have to be disconnected to use the pre out?


The AKG K712 Pro's should be well driven by the TA-26.  Did you set your source at 100% drive?, and modulate the drive from your DAC into the TA-26?

I'm finding that while it is nice to set a -15dB to -20dB attenuation on the D90 DAC to allow for more volume dial range, the best sound is when I set the D90 to 100% output (or put it in DAC mode), but then I have a very narrow "notch" to use for Volume.

I get less punch in the HD660S if I use the -15dB to -20dB D90 Pre-mode attenuation, but I don't find it so affected that it outweighs the advantage of having 9 oclock to 1 oclock on the volume dial to "play with".

But if you have a bright headphone like the AKG 712 Pro, it might sound too thin - as you are reporting - to pre-attenuate using the DAC/source, so running the source chain at 100% and dealing with the "notch" for volume range, might provide the best sound right now.  You could also try an iFi iEMatch+, see below, to allow more range on the volume dial of the TA-26.

Also, I've played with various metal combinations for IEM wires, and appled that when I bought headphone cables.  I use OCC Copper Only for bright headphones, and OCC Copper coated with Silver for everything else.

You could try getting OCC Copper cable like this one:

GUCraftsman 6N OCC Copper For SENNHEISER IE300 IE900 AKG N30 N40 N5005 4.4MM Headphone Upgrade Cable
https://www.aliexpress.com/item/1005003286992781.html

IDK if that is the correct connector for the AKG 712 Pro, so be sure to ask them first before ordering.  They were very helpful to me when I first ordered cables for my Hifiman Ananda, HE6SE, and HD660S.

I ordered all 4.4mm or 4-pin XLR ended GUCraftsman cables, nothing for 3.5mm or 6.35mm as needed by the TA-26, so I am using the stock cables from Sennheiser and Hifiman, and they all sound great to me on the TA-26.  The HE6SE V2 sounds better on the TA-20, but the Ananda sounds good to me on both the TA-26 and TA-20.

Eventually I'll order GUCraftsman cables with 6.35mm/3.5mm ends or the TA-26, probably one each OCC Copper / Silver for the Hifiman headphones - so I can swap both with Silver/Copper to see how they sound on the TA-26, on a set of Copper/Silver for the HD660S/HD600/HD650.

Interestingly I found a discussion on diyAudio discussing what tube amp specifications would be well matched to the AKG 712 Pro:

*Suggest me diy tube amp for my AKG K712 Pro*
https://www.diyaudio.com/community/...e-amp-for-my-akg-k712-pro.324786/post-5484022  <= Detailed answer

There are also attenuation/filtration adapters you can try, here's a few from iFi for 3.5mm headphone matching with low impedance headphones to headphone amps:

iEMatch+ - 3.5mm The newest version...
https://ifi-audio.com/products/iematch-plus/

iEMatch - 3.5mm Previous version, I've still found it on sale...
https://ifi-audio.com/products/iematch/

iFi also has a 2.5mm/4.4mm versions for balanced connections.

And, iFi has a previous design they still sell called the "Ear Buddy", similar ideas, attenuate power to allow turning up the amp to gain bits of resolution:

Ear Buddy
https://ifi-audio.com/products/ear-buddy/

iFi also is starting to build these iEmatch+ design features into their amps, in addition to the normal Gain settings, to help low impedance/sensitive headphones "match" with the amplifier.

I haven't tried them yet, but others have reported them helping with various low impedance headphones/IEM's matching their headphone amp/DAP/dongle


PetFju said:


> EDIT; BTW another question..I have in my budget for the next month to get either a Sennheiser HD 650 or a pair of HD 660S to use with the TA-26. Any experiences with any of these on the TA-26 out there?


It is what I am going to work on in the next month or two, depending on headphone sales, an HD600 300 ohm and an HD650 300 ohm, both might sound even better than my HD660s 150 ohm, but IDK how, as this HD660S pairs so well with the TA-26 already.

I'm going to start with the HD600 first, I've been told that is really the one to get for tube amplifiers, but others say they enjoy the HD650 the best, so perhaps I'll buy whichever is on the best discounted sale first.


----------



## alexeyi

PetFju said:


> I had an interesting experience with my TA-26 (again). I hooked up my AKG K712 Pro's, which are quite nice on tube amps according to a lot of people. This resulted in an unfortunate experience. They basically sounded the same way as Sundaras on this amp; Flat, tinny, and bass-shy. And when turning up the volume there was quite audible distortion.
> Now i have to say i didn't expect this, as the 712's are dynamic driver, 62 ohm headphones. And as such should be within the specs suited for this amp. That really sucked, i have to admit.
> For now i am still stuck on my Atrox V2 for these cans, so maybe i should run the TA-26 as a pre for that to get some tube magic out of it (even though they sound excellent on the Atrox).
> Anyways; anyone know if the pre out of the TA-26 is decoupled from the headphone jack out? Meaning; will the headphones have to be disconnected to use the pre out?
> ...



I sometimes use my HD660S with the TA-26 and I find the pairing very good even with the stock 6.35 cable. In very few cases, on some of the old songs in my library it sounds a little bit muffled, but for the rest no problem.


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## hmscott (Feb 16, 2022)

alexeyi said:


> I sometimes use my HD660S with the TA-26 and I find the pairing very good even with the stock 6.35 cable. In very few cases, on some of the old songs in my library it sounds a little bit muffled, but for the rest no problem.


It might be the tube pairing currently, as I've had the same "muffled" sound reaction with some songs - resonating to the music, building up a "standing wave" which adds an unusual pressure in my ears - which interferes with the clear sound I usually hear.

So far only the JAN RCA 5692 has completely removed that "muffled" sound, very surprising actually.  Even my "best" 6SN7GT VT-231 "Black Beauty" does it to a smaller degree, all of the VT-231's can produce that higher than normal "standing wave" pressure with some music.

I'm hoping to find other 6SN7 tubes that have less or none of that "resonance", so far the 6SN7GT has the most, 6SN7GTA has a bit less, and maybe  the 6SN7GTB will improve the sound to the 5962 pristine clean sound level.

I think I'll try the 1953 Melz with the 1950 JAN RCA 6AS7G, and see if the Melz will do as well as the 5962 - or where it falls between the VT-231 and 5962

And, this might be a great example of what some call "lifting a veil" obscuring the sound, it was very apparent when I moved from one of the 6SN7 GTA SYLVANIA NOS SAME DATE CODE TALL GLASS PLATINUM MATCHED QUAD tubes to the JAN RCA 5692, the pressure was gone and the clarity was revealed and the delivery was more dynamic with more distinct Bass.  And, when I went back to the KEN-RAD JAN CKR 6SN7 GT VT-231 1944 LEGENDARY BLACK BEAUTY CHROMED FOIL NIB MINT from the 5962, the pressure was back.

I'd like to add that for the most part I didn't notice that resonating pressure, it was only during certain tracks, and is a very small % of my music, video, etc.  In fact the fast action dynamic movie sound is awesome with the VT-231 tubes, as is R&R, same for Hip-Hop and Rap, no problems.  It is only some audio that does it.
I was trying to find a word to describe that resonating high pressure feeling, and "muffled" is a good one, thanks!


----------



## alexeyi

hmscott said:


> It might be the tube pairing currently, as I've had the same "muffled" sound reaction with some songs - resonating to the music, building up a "standing wave" which adds an unusual pressure in my ears - which interferes with the clear sound I usually hear.
> 
> So far only the JAN RCA 5692 has completely removed that "muffled" sound, very surprising actually.  Even my "best" 6SN7GT VT-231 "Black Beauty" does it to a smaller degree, all of the VT-231's can produce that higher than normal "standing wave" pressure with some music.
> 
> ...



At the moment, the IRL situation(work+personal life) does not allow me to spend my time studying and rolling tubes.
Hopefully, as we approach summer, I will have some spare time to get deeper into rolling tubes for TA-26. If I get the right combination or a specific tube that can fix the issue that seems to bother us a little, I'll post my finding here. Ultimately we are all about enjoying the music


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## hmscott (Feb 16, 2022)

alexeyi said:


> At the moment, the IRL situation(work+personal life) does not allow me to spend my time studying and rolling tubes.
> Hopefully, as we approach summer, I will have some spare time to get deeper into rolling tubes for TA-26. If I get the right combination or a specific tube that can fix the issue that seems to bother us a little, I'll post my finding here. Ultimately we are all about enjoying the music


What tubes are you listening with on the TA-26?


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## alexeyi (Feb 16, 2022)

hmscott said:


> What tubes are you listening with on the TA-26?


If I remember correctly, I have a Tung Sol 6SN7 and a SED wing 6AS7G. It has been a while since I switched the default Chinese tubes.
Sound is really clean and crisp with the combination, just what I am after. Hope it helps you.


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## hmscott (Feb 16, 2022)

alexeyi said:


> If I remember correctly, I have a Tung Sol 6SN7 and a SED wing 6AS7G. It has been a while sine I switched the default Chinese tubes.
> Sound is really clean and crisp with the combination, just what I am after. Hope it helps you.


Nice, SED tubes are made in St. Petersburg - I'll have to try to find one 

They look like the Winged C Svetlana tubes, but made more recently, ending production in 2012, where did you find yours?

Is your Tung Sol 6SN7 also a newer production tube?  Is it a GT, GTA, or GTB? Where did you find it?

If I am keeping you from school work, please answer later


----------



## alexeyi

hmscott said:


> Nice, SED tubes are made in St. Petersburg - I'll have to try to find one
> 
> They look like the same Winged C Svetlana tubes, but made more recently, ending production in 2012, where did you find yours?
> 
> ...



No, no problem. I am at work now, just had a few spare minutes to answer.
I received them from my father, I don't know where he bought them form. He is an old-school tube guy, he has his ways of getting all kind of tubes for his home equipment. After I told him about the new purchase he just got me these tubes and told me to get rid of the stock ones


----------



## PetFju

hmscott said:


> The AKG K712 Pro's should be well driven by the TA-26.  Did you set your source at 100% drive?, and modulate the drive from your DAC into the TA-26?
> 
> But if you have a bright headphone like the AKG 712 Pro, it might sound too thin - as you are reporting - to pre-attenuate using the DAC/source, so running the source chain at 100% and dealing with the "notch" for volume range, might provide the best sound right now.  You could also try an iFi iEMatch+, see below, to allow more range on the volume dial of the TA-26.
> 
> ...



I thought they would be well driven as well, which is why i was a bit let down by this. And yes, i did try different "volume options" to see if that changed anything; which it doesn't in this case. 

Also, that he 712 sounds thin has got to be some sort of misconception related to people underamping them. The reason for this statement is that when i i drive them with the Atrox V2 they sound full bodied with good bass slam and extension. Just very good really. 
They might brightly tuned in the high mids/highs, but most certainly are not thin sounding. 

It simply sounds like the TA-26 is running out of steam, as i stated; similarly to trying to run planars. Anyways, i guess i'll just stick to using Sennheisers and Beyerdynamics on the TA-26 for the time being. 

Thanx for the input on the 600-series cans. I'll try to wrap my head around it, but i guess the only real way to find out is to try..


----------



## hmscott

alexeyi said:


> No, no problem. I am at work now, just had a few spare minutes to answer.
> I received them from my father, I don't know where he bought them form. He is an old-school tube guy, he has his ways of getting all kind of tubes for his home equipment. After I told him about the new purchase he just got me these tubes and told me to get rid of the stock ones


Those are great tubes on the TA-26.  I'm happy for you that you and your father can connect with a shared hobby too.


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## hmscott (Feb 16, 2022)

PetFju said:


> I thought they would be well driven as well, which is why i was a bit let down by this. And yes, i did try different "volume options" to see if that changed anything; which it doesn't in this case.
> 
> Also, that he 712 sounds thin has got to be some sort of misconception related to people underamping them. The reason for this statement is that when i i drive them with the Atrox V2 they sound full bodied with good bass slam and extension. Just very good really.
> They might brightly tuned in the high mids/highs, but most certainly are not thin sounding.
> ...


Well, the amp / headphone impedance matching is important.  The AKM 712 Pro wants power at 62 ohms, per that posting I linked at least 500mA @ 2V, most SS amps should hae no problem doing that, including Hybrid Tube amps like the TA-20 that match better across the whole impedance range.  Headphone AMP's when they list their power output at serveral impedance measurements, can show where the amp is "happiest" to drive a load.

The AKM 712 needs to be driven at 62 ohms, and the TA-20 would do that well, but the TA-26 appears to drive higher impedances better.  The TA-26 drives the Beyerdynamic 600 ohm headphones like no other headphone amp I've used, so that shows me the TA-26 is happiest with high impedance headphones.

My Beyerdynamic DT-770 16 ohm headphones sound thin and lifeless on the TA-26, on the TA-20 the 16 ohm DT-770 sounds awesome.

My Beyerdynamic DT-880/990 600 ohm hadphones sound great on the TA-20, but not as good as on the TA-26, as the TA-26 drives 600 ohm impedance headphones best...

IDK if there is a viable solution for driving low impedance headphones on the TA-26, some work fine, some don't, all we can do is try different things, or use them on other amps.

And, save the TA-26 for the high impedance headphones.


----------



## PetFju

hmscott said:


> Well, the amp / headphone impedance matching is important.  The AKM 712 Pro wants power at 62 ohms, per that posting I linked at least 500mA @ 2V, most SS amps should hae no problem doing that, including Hybrid Tube amps like the TA-20 that match better across the whole impedance range.  Headphone AMP's when they list their power output at serveral impedance measurements, can show where the amp is "happiest" to drive a load.
> 
> The AKM 712 needs to be driven at 62 ohms, and the TA-20 would do that well, but the TA-26 appears to drive higher impedances better.  The TA-26 drives the Beyerdynamic 600 ohm headphones like no other headphone amp I've used, so that shows me the TA-26 is happiest with high impedance headphones.
> 
> ...


Yeah, that seems to be the conclusion. Which is one of the reasons i want to try a different set of Sennheisers on the TA-26. As of right now i have a pair of 58X, a pair of 560S is on the way and i have yet to decide if 650 or 660S are the ones to get. So even the 560S at 120 ohms might be not be ideal for the TA-26.
But..I have yet to try it out as a pre. It is quite possible that the TA-26 as a pre is ideal for something like the Toping A90 (or Atrox for that matter), basically a low noise high power solid state amp. I'll try it out whenever i have the time and can be bothered.

Off topic:
As for the K712's, they are primarily being used for gaming, via both a Soundblaster X-Fi surround coupled to a Little Dot 1+ for amp duty , and a Sennheiser GSX1000 coupled to the Atrox v2 as amplification.
I'm having trouble deciding if the Soundblaster or the Sennheiser dac both warrant a place in the lineup (for different games), or if i am to keep just one of them. They are useless for music, but still interesting as a surround option for gaming, dependent on the genre of games.


----------



## PetFju

@hmscott Thanks for the detailed information by the way, that goes for most posts you make, answering questions for everyone in this thread. Very enlightening and informative, and nice to have in here for people that are later to the xDuoo party than we are


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## hmscott (Feb 16, 2022)

PetFju said:


> Yeah, that seems to be the conclusion. Which is one of the reasons i want to try a different set of Sennheisers on the TA-26. As of right now i have a pair of 58X, a pair of 560S is on the way and i have yet to decide if 650 or 660S are the ones to get. So even the 560S at 120 ohms might be not be ideal for the TA-26.
> But..I have yet to try it out as a pre. It is quite possible that the TA-26 as a pre is ideal for something like the Toping A90 (or Atrox for that matter), basically a low noise high power solid state amp. I'll try it out whenever i have the time and can be bothered.


Well, if I had heard the HD600/650 before I'd feel more comfortable recommending one over the other, but given the TA-26 preference for higher impedance headphones I think it is safe to recommend trying an HD600 or HD650 first - then fall back to the least expensive option, the HD600 to try first.

The HD660s is awesome, but I can tell that because of how "lit up" the 600 ohm Beyerdynamic headphones are on the TA-26 compared to the HD660s, I'd expect the HD600 and H650 with 300 ohm impedance will be as awesoe or likely more awesome than the HD660s... but IDK for sure, I've got a subset of the experience I need to know for sure.

The correct answer is to get all 3 of them, and then decide which one you like best and either return the others or keep them to stave off the boredom that comes with using the same headphone constantly - it helps to break things up - switch up for another great sound for a while so your favorite once again can seem special - I really find it helps to have more than one great headphone.

I've spent a lot time only listening to each of them, but even the most special gets old eventually - you have a bad day, the headphone seems off, you swap in another great headphone and that picks you up and things are a little brighter once again. 

And, Sennheiser had the HD540 that released 600 ohm models in the '80's, long discontinued:

Sennheiser HD540 20 - February 2019
https://overearmania.com/2019/02/20/sennheiser-hd540/

600 ohm headphones
https://www.head-fi.org/threads/600-ohm-headphones.726817/post-10712625
https://www.head-fi.org/search/8530926/?q=600+ohm&c[title_only]=1&o=relevance


PetFju said:


> Off topic:
> As for the K712's, they are primarily being used for gaming, via both a Soundblaster X-Fi surround coupled to a Little Dot 1+ for amp duty , and a Sennheiser GSX1000 coupled to the Atrox v2 as amplification.
> I'm having trouble deciding if the Soundblaster or the Sennheiser dac both warrant a place in the lineup (for different games), or if i am to keep just one of them. They are useless for music, but still interesting as a surround option for gaming, dependent on the genre of games.


As I said, variety has it's own special value, even if the alternatives aren't your favorite, they can sound great as alternatives down the road. 

I've had CP-1, CP-3, surround sound processors for several simultaneous home theaters, but even those magical instruments lose their magic and the world moves on.

Enjoy them while you have them, and the time to find the next thing will come soon enough.


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## PetFju (Feb 16, 2022)

I have now tried hooking the TA-26 up as a preamp for the Atrox V2. I haven't really concluded yet, but first impressions are that it's just about all of the TA-26 sound, but with solid state class A power..
It plays beautifully on the AKG 712's. The sound is moist (don't you just love that word..lol) and fat but with heft and body. Very Sennheiser 58X-like, but with the clarity of the AKG's, which is what i had hoped the TA-26 could pull off on it's own. Now i'll have to try it with planars..dammit.
Does anyone know if xDuoo make a tube-pre?

Btw; The outputs (front and back) are not exclusive. They both play at the same time, and they affect each other. Plugin a headphone in the front changes the sound of the output on the other amp (not sure what it does really, but it's audible).


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## Shane D (Feb 16, 2022)

I got my amp today. Ordered Jan. 25 and received Feb. 16. That is my first, last and only order with APOS.

The amp is cool and VERY small. Gave it a bit to warm up and now it is hooked up.
BF2 to Loki to switcher to MT-602. Nice sound. Not as full and detailed as the Pro iCAN, but c’mon, it is literally ten times the price.  

I pulled my HE6se V2’s out of the iCAN and put them right into the MT-602. Not bad at all. Especially with the Loki adding EQ and some gain. I am at 1:00 and it is sounding pretty good. I had to drop down to 12:00 with a newish jazz album.

I had some channel imbalance that could be corrected by touching the tubes. I turned it off, pulled the tubes and then reset them. They ship already installed and I guess loosened in transit.


I am impressed with this little amp! I have two other sets of tubes to run through in the coming weeks. I fully expect my efficient 'phones to be a problem with this amp, but it is taking my bad boys in stride. Auditory memory sucks but I think this sounds better than when I tried to run these headphones through my Violectric V220, which I deemed a failure.




This is an amazing amp for this price. This will keep me busy for a few weeks.


----------



## DJ LP

Hello to everyone on this thread. I'm new on the thread. I have a question. I own the xDuoo X10T II Turntable, xDuoo Xd-05Plus, hooked up with a Audioquest carbon usb type c to type c and a  HiFiman HM-650, with a mini box amp card. Oh, and HiFiMan Ananda headphones. I just ordered the xDuoo TA-10R. here's why. My HiFiMan HM-650 sounds lovely with the Ananda's but since there is no way I can adjust the sound, the bass is a little thin to me. I purchased the xDuoo stuff because I could add the missing bass and yes, it sounds good. Last night the battery on the XD-05Plus died. While it was charging I grabbed the HM-650. I haven't listened to it for a year. Man Oh man. When I started listening to it, I didn't realize how textured, detailed, velvety and organic sounding the HM-650 was. It was like I was listing to music inside of the music. Plus it had way more dynamic slam, minus the sub bass. It was there, just not as much as I wanted. How much of sound quality difference is there between the XD-05Plus and the TA-10R?Will I possibly get all that I got with the HM-650? I mean that thing really sounds good. Just no type of tone controls to make adjustments to the sound. Hopefully someone can help me.


----------



## hmscott (Feb 16, 2022)

PetFju said:


> I have now tried hooking the TA-26 up as a preamp for the Atrox V2. I haven't really concluded yet, but first impressions are that it's just about all of the TA-26 sound, but with solid state class A power..
> It plays beautifully on the AKG 712's. The sound is moist (don't you just love that word..lol) and fat but with heft and body. Very Sennheiser 58X-like, but with the clarity of the AKG's, which is what i had hoped the TA-26 could pull off on it's own. Now i'll have to try it with planars..dammit.
> Does anyone know if xDuoo make a tube-pre?
> 
> Btw; The outputs (front and back) are not exclusive. They both play at the same time, and they affect each other. Plugin a headphone in the front changes the sound of the output on the other amp (not sure what it does really, but it's audible).


Yup, plugging together tha TA-26 + Atox V2 you've recreated the hybrid Tube+SS Xduoo TA-20, but with different tubes, and two components.

The TA-20 output is a passthrough of the input, the input signal doesn't go through the tubes or the SS before going directly to the AUX Out, so you cannot hook up the TA-20 like the TA-26 to add tube sound to your source chain.

I've been thinking of getting a nice SS power amp to drive with the TA-26 and power my Hifiman HE6SE V2 - as the TA-26 directly doesn't have enough power.

Xduoo hasn't produced a Tube Pre, yet 

*Update:* @PetFju - Xduoo has added a tube Pre, the Xduoo MT-603


----------



## Shane D

hmscott said:


> Yup, plugging together tha TA-26 + Atox V2 you've recreated the hybrid Tube+SS Xduoo TA-20, but with different tubes, and two components.
> 
> The TA-20 output is a passthrough of the input, the input signal doesn't go through the tubes or the SS before going directly to the AUX Out, so you cannot hook up the TA-20 like the TA-26 to add tube sound to your source chain.
> 
> ...


I am not 100% sure what you are looking for but how about this?
https://xduoo.net/product/mt-603/


----------



## hmscott (Feb 16, 2022)

Shane D said:


> I am not 100% sure what you are looking for but how about this?
> https://xduoo.net/product/mt-603/


@PetFju

Hah, I hadn't seen that MT-603 before!

I thought all the MT series were variations on numbers of tubes in the design for headphone amps , but there it is an Xduoo Pre!

Xduoo classify it in their "Tube Headphone Amplifier" category => Home / Tube Headphone Amplifier / xDuoo MT-603 Pre-Amplifier - even though the MT-603 doesn't have a headphone jack.

It is a nice start Xduoo, please branch out in the Pre line, and please give the Pre-amplfier(s) their own category


----------



## Shane D

hmscott said:


> Hah, I hadn't seen that MT-603 before!
> 
> I thought all the MT series were variations on numbers of tubes in the design for headphone amps , but there it is an Xduoo Pre!
> 
> ...


I came across that a while back when I was deciding on MT-602 or MT-604.


----------



## hmscott (Feb 16, 2022)

Shane D said:


> I came across that a while back when I was deciding on MT-602 or MT-604.


Nice, thank you for catching that and speaking up, it is nice to know that Xduoo has developed and produced a Tube Pre-amplifier. 

@PetFju

Someone on Head-fi is using an Xduoo MT-603 Pre-amplifier:
https://www.head-fi.org/threads/schiit-lokius-impressions-reviews.958856/post-16609749
https://www.head-fi.org/threads/schiit-lokius-impressions-reviews.958856/post-16609854


----------



## Shane D

hmscott said:


> Nice, thank you for catching that and speaking up, it is nice to know that Xduoo has developed and producted a Tube Pre-amplifier.
> 
> And, someone on Head-fi is using an Xduoo MT-603 Pre-amplifier:
> https://www.head-fi.org/threads/schiit-lokius-impressions-reviews.958856/post-16609854


My amp (MT-602) states that the line out can be used as a pre-amp. Is that what you are looking for? Or something different?


----------



## hmscott (Feb 16, 2022)

Shane D said:


> My amp (MT-602) states that the line out can be used as a pre-amp. Is that what you are looking for? Or something different?


Then the MT-602 output can operate like the TA-26 output as a tube buffer gain stage with volume control, but they are missing a source switcher functionality.

I think of a preamplifier as including both an active gain stage, volume control, and a source switcher, which the MT-603 preamplifier does - it has 4 inputs to one output along with an active gain stage with volume control.

Then there are Phono Pre-Amplifiers, they act as a gain stage, and sometimes include "switching" between Moving Coil and Moving Magnet matching and amplification characteristics, but are usually dedicated to one source device.  They may have switchable settings for gain, but typically they don't have a variable volume control.

All just words trying to reign in the description for the function of a device, no matter the words the device can do what it is physically able to do.  Humans need the words of description, the devices don't care.


----------



## PetFju

@Shane D @hmscott Thank you guys! That will be just about what the doctor ordered (and soon me i suppose) 
Now the question is; will the sound quality of the MT-603 equal that of the TA-26 as a pre..we shall see! Also, this gives so many opportunities as far as different "power-amps" go. The Atrox V2 that i have now has got to be one of the more powerful and sweet sounding class A amps out there for cans, at least at that pricepoint, but its design is a bit dated, and its looks are not gonna win any beauty contests either. Not that THAT matters so much though, but it's part of the total.  
Now i wish that Topping (or xDuoo for that matter) made a simple power-amp with no volume control. Anyways, as soon as i find where i want to order from i will get that MT-603, so thank you guys for pointing that out, i didn't know that one existed, even after looking at xDuoo's web page.


----------



## hmscott (Feb 17, 2022)

PetFju said:


> @Shane D @hmscott Thank you guys! That will be just about what the doctor ordered (and soon me i suppose)
> Now the question is; will the sound quality of the MT-603 equal that of the TA-26 as a pre..we shall see! Also, this gives so many opportunities as far as different "power-amps" go. The Atrox V2 that i have now has got to be one of the more powerful and sweet sounding class A amps out there for cans, at least at that pricepoint, but its design is a bit dated, and its looks are not gonna win any beauty contests either. Not that THAT matters so much though, but it's part of the total.
> Now i wish that Topping (or xDuoo for that matter) made a simple power-amp with no volume control. Anyways, as soon as i find where i want to order from i will get that MT-603, so thank you guys for pointing that out, i didn't know that one existed, even after looking at xDuoo's web page.


Well, as far as sound quality, you'll have to get one and let us know which tubes sound best. 

It is nice that the MT-603 only has 1 tube, so you can get 2x the variety of tubes to try!

Topping has some amps:
https://www.tpdz.net/amplifier

With their new PA5 the new hotness:
https://www.tpdz.net/productinfo/737898.html

The MT-603 uses a single 12AU7, but I wonder if it will support 12AT7 and 12AX7?   service@xduoo.net might know


----------



## PetFju

hmscott said:


> Well, as far as sound quality, you'll have to get one and let us know which tubes sound best.


I Will let you know  It'll take a little while yet, but it'll be interesting to see. 


hmscott said:


> It is nice that the MT-603 only has 1 tube, so you can get 2x the variety of tubes to try!


Yea. I already have quite a few different 12AU7's from the TA-20, so a lot to try 


hmscott said:


> Topping has some amps:
> https://www.tpdz.net/amplifier
> 
> With their new PA5 the new hotness:
> https://www.tpdz.net/productinfo/737898.html


I's have to get a special cable made with the speaker plugs on the amp end. Also, how about output impedance? That part is a bit over my head so to speak, but will it work well do you think?


hmscott said:


> The MT-603 uses a single 12AU7, but I wonder if it will support 12AT7 and 12AX7?   service@xduoo.net might know


I'll find out


----------



## hmscott (Feb 17, 2022)

PetFju said:


> I Will let you know  It'll take a little while yet, but it'll be interesting to see.
> 
> Yea. I already have quite a few different 12AU7's from the TA-20, so a lot to try
> 
> ...


Yeah, due to the tiny case size - creating the need for a huge external power brick - the PA5 doesn't have enough case size for connectors, so custom cables are available from Topping too, isn't that nice of them:
https://www.tpdz.net/others

The PA5 is a Class D amplifier, a different design that doesn't need banks of large capacitors or a large transformer, so most of these Class D amps are sold as boards with others combining the amp board with a power supply, box, and measurements - all it takes to become an amplifier builder these days 

There are a lot of people that swear by the Class D design, but I've not heard one.  That is why I haven't bought one, I'd need to hear a new Class Amp's sound first, on headphones.  That and the PA5 has too much power, but has great measurements, the previous PA3 didn't have great measurements nor quite enough power.  I'm still looking for an amp to drive the HE6SE V2 - with the TA-26 I've found the amp for 600 ohm headphones.

The MT-603 looks like good fun 

This post/thread has some links of interest, and before (after?) photo's of the PA5 inside:

Topping PA5 (TPA325X) : Is a modification worth it? ?
https://www.diyaudio.com/community/threads/topping-pa5-tpa325x-is-a-modification-worth-it.380233/


----------



## PetFju (Feb 17, 2022)

I got the little tube dampeners today. I have to say they actually help a little as far as noise goes.
So the tubes still will make a racket if i tap them, but now the volume wheel doesn't make the sound crackle any more. So yey 

Semi OT: I received the Sennheiser HD560 in the mail today, and have been trying them out on different amps. They work just fine with the TA-26, even at their 120ohms, so that's a good thing!
Other than that i have to say i (for the most part) like the sound of the HD560 better then the 58X. Other than for acoustic and "singer songwriter" type music, and Maybe EDM, they're much more balanced. Good budget cans for sure! Also as a bonus they are great for gaming 

Edit; Also i see i need to be dusting again..It becomes so evident in pictures with that kind of lighting  lol


----------



## albertmuc (Feb 17, 2022)

Received my „xDuoo TA-20“ today, unpacked it and was amazed at the flawless quality of the workmanship. If Sony had been listed as the manufacturer instead of xDuoo, I would have believed it. A short function check with the standard tubes, then a pair of matched "Gold Lion 12AU7 / ECC82 Genalex" installed. The xDuoo is my first headphone tube amplifier, so I was curious what to expect. I'm hooked from the first bars, it sounds like I can hear the music through a magnifying glass, and much fuller, sweeter, amazing. In combination with my LCD-X, the „TA-20“ is an asset that belies the purchase price. Let's hear where the tube develops in terms of sound. Anyway, I already realize: it is possible to listen without a tube, but it is a waste of life time!


Question’s:

The headphones should be plugged in and unplugged when the volume control is at 0.
 Turn on the amp before plug in the headphones.
Before switching off, unplug the headphones.  All right?

The xDuoo is balanced connected to the RME. The settings on the RME are:

"Auto Ref Level = off"
&
"Ref Level = + 7 dBu"
&
"Volume 0 dB"

With the previous RME settings, I listen to the xDuoo with a volume setting of 55-60.  Is there something to optimize?


----------



## PetFju

albertmuc said:


> Received my „xDuoo TA-20“ today, unpacked it and was amazed at the flawless quality of the workmanship. If Sony had been listed as the manufacturer instead of xDuoo, I would have believed it. A short function check with the standard tubes, then a pair of matched "Gold Lion 12AU7 / ECC82 Genalex" installed. The xDuoo is my first headphone tube amplifier, so I was curious what to expect. I'm hooked from the first bars, it sounds like I can hear the music through a magnifying glass, and much fuller, sweeter, amazing. In combination with my LCD-X, the „TA-20“ is an asset that belies the purchase price. Let's hear where the tube develops in terms of sound. Anyway, I already realize: it is possible to listen without a tube, but it is a waste of life time!


Congrats on a great amp! It's really a great value, for sure  


albertmuc said:


> Question’s:
> 
> The headphones should be plugged in and unplugged when the volume control is at 0.
> Turn on the amp before plug in the headphones.
> Before switching off, unplug the headphones.  All right?


I honestly don't mind any of that. This amp is "easy street" to me; connect, disconnect, turn on or off, doesn't matter it seems. My way might wear on the amp after a while, but it certainly won't kill it. And if any of the aforementioned behaviour would be damaging to the amp it really should be clearly stated and labeled on the amp, true "Murica-style" 


albertmuc said:


> The xDuoo is balanced connected to the RME. The settings on the RME are:
> 
> "Auto Ref Level = off"
> &
> ...



I find that having my RME on +7 and from there turning it down to 0 gives headroom for eq in a better way as to not overdive. Same goes for the use of the loudness, if you utilize that. However normally i just keep it at +1 and call it a day, no eq. 
Depending on the connected headphones that would run my TA-20 between 65 and 80 for comfortable to loud listening levels. 
BTW; if you upgrade the firmware on the RME you get new colorschemes for the VU, as well as an auto-DC cutoff. The DC-cutoff has saved my ass a couple of times playing random tracks on spotify actually, so it's a useful feature.


----------



## albertmuc

PetFju said:


> …I honestly don't mind any of that. This amp is "easy street" to me; connect, disconnect, turn on or off, doesn't matter it seems. My way might wear on the amp after a while, but it certainly won't kill it. And if any of the aforementioned behaviour would be damaging to the amp it really should be clearly stated and labeled on the amp, true "Murica-style"…


I'm less worried about the amp than about the Audeze headphones, because they don't like plop's…


----------



## PetFju

albertmuc said:


> I'm less worried about the amp than about the Audeze headphones, because they don't like plop's…


Obviously turn the volume down.. Anyways, take care if you swap headphones and such as far as different sensitivity etc.
I haven't noticed any bad "plops" with the TA-20 though, but that is my experience and you may not be as lucky..


----------



## albertmuc (Feb 18, 2022)

Plugged the T1.3 into the TA-20 with low expectations. Low expectations, because the Beyerdynamic already sounds warm and bassy. To my surprise, the Beyerdynamic wins enormously, especially through a plastic image and more beautiful voices.


----------



## jonathan c

albertmuc said:


> Plugged the T1.3 into the TA-20 with low expectations. Low expectations, because the Beyerdynamic already sounds warm and bassy. To my surprise, the Beyerdynamic wins enormously, especially through a plastic image and more beautiful voices. The T1.3 seems made for tubes (at least for the TA-20), despite being only 32 ohms, strange but true.


It may actually be less strange than you think. The output stage of the TA-20 is solid-state operating in class A. The output impedance (though not stated), therefore, is likely to be very low (1 ohm or less). The T1.3 headphones at 32 ohms would be well controlled by the TA-20. [The ‘damping factor’ would be 32.]


----------



## albertmuc (Feb 18, 2022)

jonathan c said:


> It may actually be less strange than you think. The output stage of the TA-20 is solid-state operating in class A. The output impedance (though not stated), therefore, is likely to be very low (1 ohm or less). The T1.3 headphones at 32 ohms would be well controlled by the TA-20. [The ‘damping factor’ would be 32.]


Control is also provided via the RME, thanks to an equally low output impedance. But over the TA-20, the T1.3 doesn't get too much bass, or too much warmth, I would have expected something like that, the T1.3 only wins!

Suffice to say, those who haven't heard the T1.3 through a matching tube amp haven't heard the T1.3 at all. Admittedly I've only heard the T1.3 on the RME, not on the more powerful SS, but the jump through the TA-20 is just massive.


----------



## PetFju (Feb 18, 2022)

https://www.audiophonics.fr/en/preamplifier-and-volume-control/xduoo-mt-603-tube-preamplifier-12au7-p-15522.html?search_query=mt 603&fast_search=fs

Usually it takes a couple of weeks to get stuff from them, but at least the order is in 

EDIT: I did get an answer from Sam at xDuoo already regarding tube compatability for the MT-603. 
Quote; "Yes, you can also use other tubes 12AT7, E180CC, 12AX7, but the best result is using 12AU7,ECC82, we already adjust the sound basis on these two tubes."


----------



## Shane D (Feb 18, 2022)

This little amp (MT-602) is still going pretty good today. I stepped over to the T60 Argons this time and I had to drop the volume from 1:00 ( with HiFiman HE6se V2's) down to 10:00. This unit will be a nightmare with efficient headphones, but I have some idea's for that.

But it really is a nice sounding little amp. This has got to be the bargain of the year! At least for harder to drive headphones.

I am REALLY looking forward to rolling my additional tubes. Hopefully they have a lower gain/amplification factor.


----------



## Silver Wolf (Feb 19, 2022)

Relaxing today (after much stress lmao!) with the TA-30 rolled (NOS TOOBZ- RCA-5U4GB/factory matched pair 68 Brimar's {99.7%)... Match sorted by friend from selective personal stocks/I am so spoilt lol...







I have way too much stuff, I spent 4 hours working through conflicts/driver/s for all my different dac's lol... I have no idea why I'm loling...was nightmare     but at last tunes flow...happy days everyone!


----------



## hmscott (Feb 19, 2022)

Shane D said:


> This little amp (MT-602) is still going pretty good today. I stepped over to the T60 Argons this time and I had to drop the volume from 1:00 ( with HiFiman HE6se V2's) down to 10:00. This unit will be a nightmare with efficient headphones, but I have some idea's for that.
> 
> But it really is a nice sounding little amp. This has got to be the bargain of the year! At least for harder to drive headphones.


That is what is so cool about the Xduoo Tube/Hybrid amps, the sound we are getting - and can get by tube rolling - is so sweet for such a small $ investment.  It really is magical sounding so easily.


Shane D said:


> I am REALLY looking forward to rolling my additional tubes. Hopefully they have a lower gain/amplification factor.


Well, the Hybrid design of the TA-20/TA-30 won't provide gain variance by rolling different tubes.  Swapping in 12AT7 from 12AU7 doesn't increase volume at the same dial setting, and it doesn't get any louder with a 12AX7 either.

The Hybrid design's pre-amp tube(s) as a fixed gain stage, and the SS stage is the actual gain stage.

The 12AU7 in the TA-20 for me gives the same volume as the 12AT7 and 12AX7, it is the sound characteristics that change.

It will be interesting to see if the Xduoo MT Hybrid models operate the same.

If the output is too hot for IEM's, then something like the iFi iematch+ would be a good adapter to plug in between the headphone jack and the IEM to attenuate the output of the headphone amp. That will give you deeper clearance into the volume dial, lower noise, and tame the gain 

If you are looking for a great sounding 12AU7 that doesn't break the bank, the Ei Yugoslavia tubes manufactured on Philips and Telefunken equipment under license for both sound sweet.  At least these sound sweet right now on my TA-20:

4 Strong Matched NOS IC Ei Yugoslavia Long SMOOTH Gray Plate 12AU7 / ECC82 Tubes
https://www.ebay.com/itm/124890637162

And, has a single "used" tube that measures well over 100%+/100%+, see numbers written on White box + Description details:

Strong Ei Yugoslavia Long SMOOTH Gray Plate O Getter 12AU7 / ECC-82 Tube
https://www.ebay.com/itm/125087578210

And, there are other combinations and a 12AX7 listed, and if you ask desireme1979 nicely she might have a new boxed single tube available.  These sellers usually have a varying stock much larger than they can keep listed at one time:
https://www.ebay.com/sch/i.html?_dmd=2&iconV2Request=true&_ssn=desireme1979&store_cat=0&store_name=michelleselectronictubesnmore&_oac=1&_nkw=ei yugoslavia

These IC Ei Yugoslavia Long SMOOTH Gray Plate 12AU7's are the most sweet sounding 12AU7 tubes I've tried - if bought/heard these first I might not have even branched out to 12AT7's soon quickly!  While not as euphonic as the 12AT7/Brimar 6060/Mullard 8126/E180CC it is great sounding without any negative attributes that I have heard in the last few days.  Easily a great recommendation for a first/last 12AU7, especially if you can get a discount because it is used but measuring over 100%+/100%+.


PetFju said:


> https://www.audiophonics.fr/en/preamplifier-and-volume-control/xduoo-mt-603-tube-preamplifier-12au7-p-15522.html?search_query=mt 603&fast_search=fs
> 
> Usually it takes a couple of weeks to get stuff from them, but at least the order is in
> 
> ...


That's great news, plenty of options for tube rolling!

BTW, the 12AU7 is the US designation and the ECC82 is the European name.  Same tube, different "standard" name.  Gotta love standards that come up with a new name to "clarify" things 

The MT-603 product page doesn't mention anything about Transistor stage, so the MT-603 is all "tube" sound, so that will be fun!  No interference from SS "cleaning" up the sound, it should be full euphonic with 12AU7 instead of a 12AT7 to "liven" up the sound.

Please see the Seller desireme1979 store, she has lots of single tubes with clearly labeled measurements in the photo's - written labels on the "white box"- and in the listing detailed text description. Measurements over 100%+/100%+ are technically close to new and should sound new too. desireme1979 is easy to message and get to know, you can let her know you are starting out and she will recommend inexpensive tubes - a good place to order any time, but especially early on when you are learning.

Lots of fun


----------



## Mansinthe86

Im currently considering getting a tube amp just for fun. I know it doesn't measure that we'll. 

Should have balanced Inputs, balanced headphone socket (XLR).

But how does something like the xduoo TA20 work with low impedance headphones like the focal Elegia or planar magnetic Headphones like the Aeon Noire 2?


----------



## Ike1985

TA-26 Review:

Setup:

2021 Macbook pro  shielded cable micro usb in  Hugo2 RF output  RF into TA26 --> custom 64 Audio A18t

I struggled with EMI/RF issues through this entire review session, I did everything in the book including spending $300 on various cables and EMI/RF blocking solutions ultimately to no avail. I had the best luck by simply maxing out the volume on my Hugo2 and turning the volume up to the minimum on the TA26, this resulted in the least amount of perceived interference.

Resolution:

The TA26 punches far above it’s price point with regard to resolution, a very detailed desktop amp indeed. Its’ resolution is helped by the fact the mid and sub bass are extremely controlled with regard to decay and do not bleed into the rest of the sound. There’s an overall sense of clarity I haven’t heard in many tube amps until you get into the thousand dollar price ranges. The TA26 has more of an audiophile style presentation with a very clear sound as opposed to the typical warm tube sound. I don’t mean to say the TA26 can compete on a detail retrieval level with good solid state Amps but that it has more of their tonality than a tube amp and as a result of that presentation you have more of a solid state style overall sound. It’s the tube amp that isn’t tubey.

Bass:

Clean and deep are the two words I would use to describe TA26 bass. Noticeably missing is the characteristic tube warmth and decay I’m used to as stated previously this amp goes for a super clean high resolution presentation. Sub bass goes deep, I would describe it’s quantity as neutral. I get slightly more decay with sub bass than mid bass but more sub bass quantity than mid bass quantity as it aims more for deep tonality than quantity of bass. Great texture can be observed in the bass. Rumble was satisfying enough for me, would have liked a bit more slam.

Mids:

The midrange especially vocals are on the more intimate side, instruments have good wide staging as is to be expected on tube amps, above average I would say. I don’t find mids overall emphasized more than the highs or lows, I find them to be mostly on the same level with regard to anything jumping out at you. It’s a balanced tuning. I hear a bit more mid-high preference than low’s but that’s only if I’m trying to tease out differences and really focusing on it, in typical use I don’t notice it much.

Highs:

The highs are tuned to be inoffensive and contribute greatly to the level of detail and balanced signature.

Stage:

Overall the size of the stage is medium, not huge nor small but in between. It leans toward holographic as opposed to wide.

Separation:

The separation is superb, probably some of the best I’ve heard in a tube amp. Much of the sense of stage spacing from this amp is created by it’s superb level of separation. Even though the stage isn’t huge as compared to some other amps the TA26 takes a different approach and focuses on creating the clearest distinction between the different instruments creating a kind of spatial illusion. I am very much a fan of this, as stated repeatedly it’s a very clean sound.


----------



## Silver Wolf (Feb 19, 2022)

Mansinthe86 said:


> Im currently considering getting a tube amp just for fun. I know it doesn't measure that we'll.
> 
> Should have balanced Inputs, balanced headphone socket (XLR).
> 
> But how does something like the xduoo TA20 work with low impedance headphones like the focal Elegia or planar magnetic Headphones like the Aeon Noire 2?



I use the TA-20 balanced (with DAC feeding BAL) with the Elegia's and Aeon Flow X (all my headphones dynamic/planar low/high impedance etc) get their time on the TA-20, TA-20 doesn't care as it's hybrid and It's rated from 8-600 ohms if I remember correctly.


----------



## ClicketEKlack

Listening to Qobuz Hi-Res today, I realized I don't want any more from a headphone rig than the sound I'm getting out of this setup. $170 = endgame amp. Thank you, Xduoo!!!


----------



## albertmuc

YouTube:

Xduoo TA20 = Sweet spot

​


----------



## kibot

Privet,guys!!✌
So i get my absolutely new TA-26(the audio-store change it on my previous one with broken transformer)  and its have hellyeah awesome sound!!!!🤟🤟🤟👌


----------



## albertmuc (Feb 21, 2022)

I am very satisfied with the "xDuoo AT-20", currently with "Gold Lion 12AU7 / ECC82 Genalex", incoming "RFT foil getters".
LCD-X and T1.3 sound better than plugged into the RME. The tube-amp will stay with me.
As @hmscott said, “It really is magical sounding”!

Nevertheless, I remain curious as to which tube-amp, suitable for low-impedance headphones, would offer a real increase in sound… or how would the sound of the “Woo Audio WA6” differ…


----------



## jonathan c

albertmuc said:


> I am very satisfied with the "xDuoo AT-20", currently with "Gold Lion 12AU7 / ECC82 Genalex", incoming "RFT foil getters".
> LCD-X and T1.3 sound better than plugged into the RME. The tube-amp will stay with me.
> As @hmscott said, “It really is magical sounding”!
> 
> Nevertheless, I remain curious as to which tube-amp, suitable for low-impedance headphones, would offer a real increase in sound… or how would the sound of the “Woo Audio WA6” differ…


I think that the RFT ECC82 foil getters in your TA-20 will be an epiphany for you…As for the WA6, its ‘sound’ will be largely, but not wholly, dependent upon the rectifier tube (part of the AC-to-DC conversion).


----------



## kibot

So i was listening my new TA 26 with takstar hf 580 about few days and what can i said - there are some songs where i hear clipping and i dont know becouse of what?
If it becouse of planar headphones - why so many songs sounds so awesome?! 🤷‍♀️
Also that is not cuz of Dacmagic cuz when i use my iBasso DX80 as a sourse i also hear clipping in some songs🤷‍♂️


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## hmscott (Feb 27, 2022)

kibot said:


> So i was listening my new TA 26 with takstar hf 580 about few days and what can i said - there are some songs where i hear clipping and i dont know becouse of what?
> If it becouse of planar headphones - why so many songs sounds so awesome?! 🤷‍♀️
> Also that is not cuz of Dacmagic cuz when i use my iBasso DX80 as a sourse i also hear clipping in some songs🤷‍♂️


The Xduoo TA-26 specifications list headphone impedance compatibility of 60 ohm to 600 ohm.   The Takstar HF 580 measures 36 ohms, and specifications list 32 ohm.

I have a Beyerdynamic DT770 16 ohm that doesn't sound good on the TA-26, thin sound compared to listening on my TA-20.

My 150 ohm Sennheiser HD660s sound great on my TA-26, as compared to my TA-20, and I've heard that 120 ohm or higher works best on the TA-26.

My Beyerdynamic DT880/DT990 600 ohm headphones sound best on my TA-20 too, in fact the best I have heard them - like the Sennheiser 150 ohm HD660s.

I'm probably going to get a Sennheiser HD600 300 ohm or HD650 300 ohm next, to try on the TA-26


----------



## kibot

hmscott said:


> The Xduoo TA-26 specifications list headphone impedance compatibility of 60 ohm to 600 ohm.   The Takstar HF 580 is 36 ohms.
> 
> I have a Beyerdynamic DT770 16 ohm that doesn't sound good on the TA-26, thin sound compared to listening on my TA-20.
> 
> ...


Thanx for answer , so i realy like HF580 sound and dont want to sell it and also i really like my TA 26😢

So what can you say about Sennheiser HD 6XX  for  TA-26?
​


----------



## hmscott (Feb 27, 2022)

kibot said:


> Thanx for answer , so i realy like HF580 sound and dont want to sell it and also i really like my TA 26😢
> 
> So what can you say about Sennheiser HD 6XX  for  TA-26?


Well, I wouldn't sell your HF580 as I really enjoy my Sendyaudio Aiva headphones with impedance 32 ohm on my TA-20, and I've read the HF580 planar has the same/similar drivers as my Sendyaudio AIVA, so yeah, I would keep them!

My 600 ohm Beyerdynamics sound best on the TA-26, along with my 150 ohm Sennheiser HD660s.

I've not heard Sennheiser HD600/HD650 300 ohm headphones on the TA-26, so I cannot say for certain they would be better sounding in comparison to my 150 ohm Sennheiser HD660s, but if the Sennheiser HD600/HD650 300 ohm headphones sounded better on the TA-26, I wouldn't be surprised.

If you do get Sennheiser HD600/HD650 300 ohm headphones for your TA-26, please let us know how you like them!


----------



## kibot

hmscott said:


> Well, I wouldn't sell your HF580 as I really enjoy my Sendy Aiva headphones with impedance 32 ohm on my TA-20, and I've read the HF580 planar has the same/similar drivers as my Sendyaudio AIVA, so yeah, I would keep them!
> 
> My 600 ohm Beyerdynamics sound best on the TA-26, along with my 150 ohm Sennheiser HD660s.
> 
> ...


Yeah HF 580 have the same one and it sounds absolutely awesome and i thought that this model and other planars need powerfull amplification regardless of its impedance🤷‍♀️
Maybe i need do something with volume lavel in Windows , DAC  and TA26 ?


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## hmscott (Feb 27, 2022)

kibot said:


> Yeah HF 580 have the same one and it sounds absolutely awesome and i thought that this model and other planars need powerfull amplification regardless of its impedance🤷‍♀️
> Maybe i need do something with volume lavel in Windows , DAC  and TA26 ?


You can optimize the source chain fidelity by running them at the fixed output of 100%.  Just like a fixed output DAC/CD/Tuner/etc you want to run the Windows output at 100% too. As you drop the volume the S/N ratio drops.

And, on a DAC if it has a digital volume variable output you lose bits of resolution as you drop the volume output.  At first it doesn't matter much @ 24 or 32 bit resolution if your source is 16 bit, but as you further drop the volume or listen to a higher bit rate recording it can cut into the fidelity.

The TA-26 with full D90 2V output with my 150 ohm Sennheiser headphones limits the volume dial range, so I do drop the output of the D90 by -10dB or -15dB or up to -20dB to get the volume dial range I want, but if I leave it on -15dB I don't need to play with it.  Then the TA-26 volume dial can be adjusted above 9 oclock to 12 oclock - it does get loud 

With the 600 ohm headphones I can run the full D90 2V 100% 0.0dB full output and the volume dial has plenty of travel.

I always run 100% output on my Windows 10 PC.  I've found Tidal and other apps occasionally reset their output below 100%, so I check to make sure they are also at 100% output.

That is another reason I want to try the Sennheiser HD600 / HD650 300 ohm impedance headphones, 300 ohm should be a good place to be on the TA-26 Volume as well.


----------



## kibot

hmscott said:


> You can optimize the source chain fidelity by running them at the fixed output of 100%.  Just like a fixed output DAC/CD/Tuner/etc you want to run the Windows output at 100% too. As you drop the volume the S/N ratio drops.
> 
> And, on a DAC if it has a digital volume variable output you lose bits of resolution as you drop the volume output.  At first it doesn't matter much @ 24 or 32 bit resolution if your source is 16 bit, but as you further drop the volume or listen to a higher bit rate recording it can cut into the fidelity.
> 
> ...


Grat thnx for advice ✌- as i understand  i need use Win. and Dacmagic level on max(100%) and regulate volume on TA 26 right?


----------



## kibot

Ah i forget to say that i use APO EQ with Peace plugin in Win and it have -9dB level of gain


----------



## PetFju

MT-603 has arrived and has been tested very briefly. 
First impressions; This thing is tiny!  I don't know what i expected, but it has a very small footprint. It is very light as well, so heavy cables almost makes it topple over.
As far as sound goes; Stock tube installed first few listens gives the tubeish sound i was expecting, but with too much muddiness. The natural sibilance of "Sh" sounds and "th" sounds as well as high pitch guitar plucking is muted and veiled. So much so that it lacks significantly in detail. 
I know the tube obviously isn't close to being burnt in or sounding the way it probably will after some hours of listening, but as i couldn't bear it i had to swap it. I installed a clear top RCA tube, which i have previously used in the TA-20, so it has some hours of runtime. That sure changed things. The sound is still tubeish, but now the treble and detail is back  Very amusing. 
As i said these are the very very first impressions (talking less than two hours of playtime) and as such should not be taken as gospel. What i can say is that it does something, but then again as it is a tube-buffer it really should  
I will continue listening with it installed the chain between the ADI-2 and the Atrox V2 as well as between the Sennheiser GSX1000 and the Atrox V2, and give it some hours and then try to compare it to using the TA-26 as a pre, as well as with it removed. This will all be a while though, as i am quite busy these days and don't really have time to sit down and listen closely and analyze everything.  

But there you go, those are my first impressions. Have a great week


----------



## kibot

PetFju said:


> MT-603 has arrived and has been tested very briefly.
> First impressions; This thing is tiny!  I don't know what i expected, but it has a very small footprint. It is very light as well, so heavy cables almost makes it topple over.
> As far as sound goes; Stock tube installed first few listens gives the tubeish sound i was expecting, but with too much muddiness. The natural sibilance of "Sh" sounds and "th" sounds as well as high pitch guitar plucking is muted and veiled. So much so that it lacks significantly in detail.
> I know the tube obviously isn't close to being burnt in or sounding the way it probably will after some hours of listening, but as i couldn't bear it i had to swap it. I installed a clear top RCA tube, which i have previously used in the TA-20, so it has some hours of runtime. That sure changed things. The sound is still tubeish, but now the treble and detail is back  Very amusing.
> ...


Spasibo for review - i want it or mt 602(or 601)  for use as tube buffer between DACmagic plus and Audionet AMP 3


----------



## -Darkstar-

Ok, I've had my TA-30 for over a month now and I thought I'd share some thoughts. After a couple of weeks of owning my Ananda's, I decided they were good enough to warrant a better DAC/Amp than the Apogee Groove, I had been using with my computer. I looked at a number all-in-one dac/amps, but I was intrigued by a tube rectified hybrid at this price point, so after reading a couple reviews, I decided to give it a shot, it was also 10% off on Amazon.

It was nicely packed, with bubble wrap covering the outside. The package looked in great condition so thanks, DHL. The build quality is solid but not premium, which is fine for this price, no complaints. The first 20 hours it ran quite hot, like I had read in reviews, but it settled down a bit and is fine, but I do wonder if this heat will affect the non-amp functions over time. Break-in took around 90 hours and sounded quite closed in, with very loose bass until then.

Like every other hybrid I've heard, I can hear a bit of bloom from the tubes, but nothing like all tube designs. With the stock tubes, the sound is quite silky in the highs and the bass is pretty powerful, with nice impact and bit of extra thickness. Staging seems wider with all my headphones and it definitely sounds like a powerful amp in dynamics. It has paired well with the Ananda's, with a thickening in the highs and more impact in bass. They don't need much power to get loud, but they definitely have responded to the extra power.

With my TH900mk2's, it's a mixed bag. On well recorded material, with tight bass, it can sound amazing, especially with electronica.  The pairing can be unforgiving with compressed recordings and looser bass in some live recordings. It never gets bright in the highs, but this amp doesn't have the midrange bloom that my HP8 has, so I end up playing it at a louder level which can be good or bad in the bass department. The TA-30 is less resolving than the HP8 but is more impactful in the bass and I can tell it has a lot more power.

All in all, I am very pleased with it and with some better tubes that give more treble extension, I think it could be even better. I will say that I wish it had a gain switch because I can only use a small amount of the volume nob.


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## albertmuc (Mar 6, 2022)

Found it in the mailbox today…


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## Shane D (Feb 24, 2022)

This amp has made quite an impression on me, good and bad.

First, the bad: I don’t find it at all “tubey”, much like every other hybrid tube amp I have ever bought. You’d think that eventually, I would learn. 

On the upside, this is one impressive little amp! I ran the HE6se V2’s at 1:00. I ran the T60 Argon’s at 10:00 and am now running the Elex’s at 8:30-9:00. I am also running the Schiit Loki with it.
The sound is really good! It does not match my big amps, but they cost ten times more. It feels a little less detailed and a little thinner, but it punches WAY out of its range! I am now on the second set of tubes (Voshkods) and will get to the JAN 5654W’s next week.
Because it does not give me the “tubey” component that I was looking for, I will likely end up selling the whole package on. But if you are short on money or just starting out, this is one hell of an amp. Of course it can get complicated with really efficient headphones and probably useless with IEM’s (Very high built-in gain).

Quite the little power house. Today it is giving my Violectric V220 a good run for it’s money. Not quite as full or detailed but, with the Loki, they seem pretty close.


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## hmscott (Feb 27, 2022)

kibot said:


> Grat thnx for advice ✌- as i understand  i need use Win. and Dacmagic level on max(100%) and regulate volume on TA 26 right?





kibot said:


> Ah i forget to say that i use APO EQ with Peace plugin in Win and it have -9dB level of gain


Ahhhh, well if you are using the APO EQ of -9dB of gain in Windows, that is the same as reducing the volume below 100% - you might try 90% volume in Windows with the APO EQ disabled or set to 0.0 on the gain.  That way you can gauge what the -dB in APO EQ equals in Windows volume reduction numbers.

Again, it is best to keep the signal to noise ratio such that your source is at 100% output, Windows volume at 100.

For example, I have my D90 driving my TA-20 with the XLR output of my D90, and the RCA output of my D90 driving the TA-26.

When I reduce the output of the D90 by -20dB so the TA-26 can get more range on the Volume dial, I then need to increase the volume on the TA-20 by about 20 count, say from 55 to 75, and if I set the D90 to -10dB for the TA-26 I then need to run the TA-20 at 65.  All along I have Windows and Application volume set to 100%.

Are you able to attenuate the output of your DAC and run Windows / APO at 100% source output?  Perhaps compare the sound quality of reducing volume using Windows / APO EQ controls vs running Windows/source at 100% and attenuating output at the DAC.

There are fixed attenuation RCA inline devices you could insert between your DAC and the TA-26 as well.  Or add attenuataion at the Headphone by inserting an iFi ieMatch+.

Or, get higher impedance headphones to reduce the need.  120 ohm, or better yet 300 ohm or even 600 ohm headphones work great on the TA-26

Because I have the HD660s I will also consider getting the 300 ohm HD800 or 300 ohm HD820.

There are so many possibilities


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## albertmuc (Mar 6, 2022)

Due to my lack of experience with tubes, I am not able to compare the sound of the xDuoo AT-20 with other tube amps, therefore, I limit myself to the following:
With the "RTF ecc82 12au7 foil getter" the freshness in the sound is retained, added is a welcome warmth and physicality, which positively complements the RME.
The "Gold Lion 12AU7 / ECC82 Genalex" sound, after 30 hours of break-in, comparatively smooth and less exciting.


----------



## kibot

hmscott said:


> Ahhhh, well if you are using the APO EQ of -9dB of gain in Windows, that is the same as reducing the volume below 100% - you might try 90% volume in Windows with the APO EQ disabled or set to 0.0 on the gain.  That way you can gauge what the -dB in APO EQ equals in Windows volume reduction numbers.
> 
> Again, it is best to keep the signal to noise ratio such that your source is at 100% output, Windows volume at 100.
> 
> ...


Thank you i will try it
So i dont understand why clippng take place not in all songs ? (many songs sounds awsome) 🤷‍♀️


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## kibot

Soo it works - i used 100% of volume in Dac and Wn but -11.5 dB in APO EQ and now all songs sounds better - greatest SPASIBO ,*hmscott* !!!!!

And now look at my pretty boi 😁😁😁


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## hmscott (Feb 27, 2022)

albertmuc said:


> Edit: The seller described the tubes as "new nos" and illustrated them as such, so I'm a bit surprised at the heat discolored legs. What must be considered when buying to get really unused old goods?  Or is only the delivery of used tubes to be expected and I think too much?


Yes, that is a bit of a raw look, but I've seen it before on new tubes.  It is part of the manufacturing process.  There are several steps when heat is applied to the tube envelope and depending on the sophistication of the process - machinary or hand done - the pins can show the effects of the heating.

Also, I noticed you are from Germany, and thought I would mention there are awesome locally made RFT tubes - made in Germany - you might have easy access to by local dealers.  Also, some of the top tubes for audio were made in Germany: Telefunken. Siemans, RFT, Amperex, AEG, Lorenz, Philips and Philips Mini Watt, Cerberus, Tungsram, Valvo, RCA, Sylvania, and more.


albertmuc said:


> Due to my lack of experience with tubes, I am not able to compare the sound of the xDuoo AT-20 with other tube amps, therefore, I limit myself to the following:
> With the "RTF ecc82 12au7 foil getter" the freshness in the sound is retained, added is a welcome warmth and physicality, which positively complements the RME.
> The "Gold Lion 12AU7 / ECC82 Genalex" sound, after 30 hours of break-in, comparatively smooth and less exciting.
> Changing tubes is, also because of the submerged location on AT-20, a bit of a hassle, making comparisons unpleasant.


That was a very good explanation, "less exciting" says it all.

You will gain your words to explain details as you read others reviews and comments, but really it is always best in ones own simplest terms.  In the end it comes down to a few simple words to explain the sound.  And, whether you enjoy it or not.

I use a microfiber cloth on cold tubes to insert and pull them out.  For hot tubes - turn off the amp before pulling them out or inserting new tubes! - I use a medium thick kitchen dishes glove, not a used one, and it is much easier to grab onto the tube without much pressure and to rock it a little to the sides to loosen it and it pops right out.  It doesn't matter what size the glove is, I don't put it on, I simply wrap the wrist of the glove over the top of the tube and use my fingers to hold up the slack and direct the tube into the tube socket with the correct orientation and then click into the key slot and push down.  I use the Glove like the Microfiber cloth to get leverage and a better grip on the cold or hot tube than my hand provides alone.

Right now I have had the Mullard Holland E180CC tubes in mostly, as I need to return a couple of the newer tubes I've gotten due to IEM HISS and Static Noise, 2 sets on my TA-20 and one Tube on the TA-26.

One set I can only return, another I am sending back to swap for another pair - he's going to screen them for noise, and another tube for my TA-26 also had the static crashes. and he is also going to screen for a noise free tube.

I hadn't had a problem with noisy tubes for quite a while - since I only started buying tubes with measurements 100+/100%+, and then this last batch I ran into 3 sets with HISS and random noise problems.  Fortunately I was able to return them all.  It is important to only buy from sellers that allow returns, and even better those that will work with you to help you find what you need.

I should also mention that I don't usually hear such noise in my headphones, even with old used tubes, it is when I switch to IEMs that I will hear HISS on used tubes that have been "used up" to the point they start emitting high frequency hash noise, or HISS.

This time the static crashes of noise I was hearing were coming through on my headphones too, it was very unusual.  But, for all 3 pair/single the noise was only heard with those tubes, not with any other of my NIB (new in box) tubes, or used tubes measuring greater than 100%+/100%+.

I'm happy you are enjoying your Xduoo TA-20, Rock on!


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## jonathan c (Feb 25, 2022)

To @albertmuc (and others): it is a good idea, regardless of appearance, to thoroughly clean the tube pins before first use. I have used Barkeeper’s Friend (powder cleaner with oxalic acid), water rinse, final clean with isopropyl alcohol. During this, the tube pins are always facing down. My tube OCD?…I want those tube pins to be _shiny_!


----------



## Shane D

Another MT-602 update. I knew these were going to be an issue with very efficient headphones and I had a few different idea’s on that. Well today is show time and I am using my Grado’s with this amp, with help.


Today’s chain is Laptop to BF2 to Schiit Loki to Violectric V220 (had to open the case to change a few jumpers), line out to MT-602 and then on to my Grado’s.
Running the V220  at -12Db’s gain via the internal jumpers. Now the MT-602 is on 12:00 and I am running Voshkods. Cool.

First time ever using a pre-amp.


----------



## kibot (Feb 27, 2022)

Shane D said:


> Another MT-602 update. I knew these were going to be an issue with very efficient headphones and I had a few different idea’s on that. Well today is show time and I am using my Grado’s with this amp, with help.
> 
> 
> Today’s chain is Laptop to BF2 to Schiit Loki to Violectric V220 (had to open the case to change a few jumpers), line out to MT-602 and then on to my Grado’s.
> ...


Oh my....what a perfect setup😍😍😍

What about mt 602 as a preamp - do it have any noices??
I want it also as a preamp for my poweramp and speakers but for ex. TA 26 give a huge level of noise in speakers when i tried to use it as a preamp


----------



## hmscott

kibot said:


> Oh my....what a perfect setup😍😍😍
> 
> What about mt 602 as a preamp - do it have any noices??
> I want it also as a preamp for my poweramp and speakers but for ex. TA 26 give a huge level of noise in speakers when i tried to use it as a preamp


What kind of noise?  Did you unplug your headphones from the TA-26 when using it as a Preamp?  How long are your RCA cables to your AMP from the TA-26?  Are those RCA cables well shielded?  Is the noise a hum/or high frequency "hash" - variable not constant?

I had problems with my Topping A90 RCA output, and I had to find cables with a Quad Shield design - floating shield at destination (RCA shield), and that got rid of the noise for me.

Before that I tamed the ground loop noise by upgrading my power strips on consolodating the power to the connected chain of devices and that remove that noise source.

Later I bought a Ravpower Battery powered Pure Sine Wave power source to run my Topping A90 / D90 - and that wasn't connected in any way to the local ground - such small battery sources don't have ground connections when running disconnected from charging power - and this one has a charger that is also ungrounded.  That change took away more noise and increased the black silent backgroud.

What also can help is using XLR connections, with a similarly Quad Shielded floating shield at destination (XLR cable shield), which the D90/A90 support.

IDK if getting RCA to XLR converter at the TA-26 end, and self-powered speaker / pre/integrated amp with XLR input might also help reduce the noise.

It took me a while to work all this out with my set up, so please hang in there an keep trying solutions


----------



## Shane D

kibot said:


> Oh my....what a perfect setup😍😍😍
> 
> What about mt 602 as a preamp - do it have any noices??
> I want it also as a preamp for my poweramp and speakers but for ex. TA 26 give a huge level of noise in speakers when i tried to use it as a preamp


I had to use the V220 as the pre-amp to get around the very high gain that the MT-602 has. With efficient headphones, it needs the help.


----------



## kibot

hmscott said:


> What kind of noise?  Did you unplug your headphones from the TA-26 when using it as a Preamp?  How long are your RCA cables to your AMP from the TA-26?  Are those RCA cables well shielded?  Is the noise a hum/or high frequency "hash" - variable not constant?
> 
> I had problems with my Topping A90 RCA output, and I had to find cables with a Quad Shield design - floating shield at destination (RCA shield), and that got rid of the noise for me.
> 
> ...


Hello!✌
No - without headphones 
Cable - In-Akustik Star Audio Cable, RCA, 1.5 м

Full setup -         PC = DAcMAgicPlus = Cordial CFU 3 FC Cable = TA 26 = In-Akustik Star Audio Cable, RCA, 1.5 м = Audionet AMP 3


----------



## hmscott (Feb 27, 2022)

kibot said:


> Hello!✌
> No - without headphones
> Cable - In-Akustik Star Audio Cable, RCA, 1.5 м
> 
> Full setup -         PC = DAcMAgicPlus = Cordial CFU 3 FC Cable = TA 26 = In-Akustik Star Audio Cable, RCA, 1.5 м = Audionet AMP 3


I looked up the cables, translated, I see the In-Akustik has a ground wire - are you connected it?  The Cordial cable is XLR to RCA? 

I haven't hooked up the output of the TA-26 yet myself, so IDK what to expect... I was thinking of getting a Topping PA5 to try.

I did try to "chain" the output of the TA-20 to my Topping A90 - there was no noise, but I didn't enjoy the sound qualities - I'm kinda picky 

Besides the noises how does the quality of the TA-26 to AMP 3 sound?  Or is it just noise?  Maybe try a different power socket for the TA-26/AMP3 - try to break the ground loop - if it is ground loop noise.

Is there AC Hum?  Can you please describe the noise(s) you are hearing?


----------



## kibot

hmscott said:


> What kind of noise?  Did you unplug your headphones from the TA-26 when using it as a Preamp?  How long are your RCA cables to your AMP from the TA-26?  Are those RCA cables well shielded?  Is the noise a hum/or high frequency "hash" - variable not constant?
> 
> I had problems with my Topping A90 RCA output, and I had to find cables with a Quad Shield design - floating shield at destination (RCA shield), and that got rid of the noise for me.
> 
> ...


I think that the noice cuz of PC - when i open any game it  make the noise louder


----------



## kibot (Feb 27, 2022)

hmscott said:


> I looked up the cables, translated, I see the In-Akustik has a ground wire - are you connected it?  The Cordial cable is XLR to RCA?
> 
> I haven't hooked up the output of the TA-26 yet myself, so IDK what to expect... I was thinking of getting a Topping PA5 to try.
> 
> ...


No - where to connect ground wire ?

Yeah - Cordial is XLR to RCA

Nice quality of sound but with noise like  radio interference with 50Hz(that part of noise quiet)


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## hmscott (Feb 28, 2022)

kibot said:


> I think that the noice cuz of PC - when i open any game it  make the noise louder


Aha! 

If you can find somewhere to purchase one of these:

iFi iDefender+
https://ifi-audio.com/products/idefender-plus/

Topping HS01 USB 2.0 High Speed Audio Isolator
https://www.tpdz.net/productinfo/733226.html

The noise is coming from the PC through the 5V lines of your USB cable to the DAC.  Both devices isolate or interrupt the 5V line, and both devices allow injection of clean 5V power - through a USB-C connector on the body of their device - to replace the power from the PC.  I am using both right now on 2 USB connections out of my PC and both are working to stop the GPU induced / noisy PC noisess that come through that 5v Power lines through the USB.

Here is a video / audio of the PC noise and how the iFi iDefender+ gets rid of it, before and after:


Is that the PC noise you are hearing?

The HS01 also works, this isn't a demo of interrupting the PC GPU noise as the previous one, but it shows a big drop of PC/GPU induced USB borne noise as well:

Improving DAC Sound Quality: Topping HS01 High-Speed Isolator Review


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## hmscott (Feb 27, 2022)

kibot said:


> No - where to connect ground wire ?
> 
> Yeah - Cordial is XLR to RCA
> 
> Nice quality of sound but with noise like  radio interference with 50Hz(that part of noise quiet)


No, the ground wire would normally only be used for Phono - Turntable RCA connections.  If you were using the ground wire I would have suggested disconnection and taping it back so the ground wire doesn't touch anything - it can act like an Antenna which can pick up strong RFI/EMI - near by radio stations.  I also see the AMP III doesn't have a ground connection option, same for the TA-26.

Good to hear that the underlying sound is good.  Too bad about the 50hz, so you have a "hum" problem too besides the PC induced noise - but it might all be due to the 5V wires in the USB cable.

BTW, a quick "hack" is to figure out which two USB wires are the 5V and "cut them", as long as your DAC doesn't need the 5V signal to operate or needs the 5V signal to identify there is a connection.

Does your motherboard have an Optical output port?  Some do, and although it is a lower maximum bit rate, it will work fine for 44.1khz and 48khz recordings, and an Optical cable doesn't conduct the PC noise.

Does Amazon deliver to your area?  That is where I bought the iDefender+:
https://www.amazon.com/iFi-iDefender-External-Ground-Eliminator/dp/B0849JGL93

And, there are several listings for the Topping HS01 on Amazon, here is a"Prime" listing, and Hifigo.com also sells the Topping HS01:
https://www.amazon.com/Topping-Isolator-Compatible-PCM32bit-withstands/dp/B09MF9VTQG
https://hifigo.com/products/topping-hs01-usb-2-0-high-speed-audio-isolator?variant=42022435782895


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## kibot (Feb 27, 2022)

hmscott said:


> Aha!
> 
> If you can find somewhere to purchase one of these:
> 
> ...



Thaaanks!!!!🤟🙏

When i use Dacmagic as preamp - there are no any noises

And what about  connection of  ground wire - where to connect it??


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## hmscott (Feb 27, 2022)

kibot said:


> Thaaanks!!!!🤟🙏
> 
> When i use Dacmagic as preamp - there are no any noises
> 
> And what about  connection of  ground wire - where to connect it??


Unless the equipment has a ground "lug" there is no reason to connect a ground wire, and connecting it can cause problems - noise - induced from the non-shielded ground wire. In some situations you would ground all of your equipment, but that would be a real ground solution, including driving a 3'-6' copper rod into the ground - or tapping into the building ground system - but simply connecting all of your chassis with wire might bring about more noise problems with no ground "sync/drain" to bleed off the excess energy.

Also, if a cable has a built-in separate single wire ground wire I usually bend it back along the cable and tape it there so it doesn't "fly free" and touch metal causing problems.

The Dacmagic might have better noise prevention / isolation internally that the TA-26 doesn't, as my Topping A90/D90 also had a similar noise problem, so we need to fix the problem at the source so it doesn't get passed through our cables/devices.


----------



## kibot (Feb 28, 2022)

hmscott said:


> Unless the equipment has a ground "lug" there is no reason to connect a ground wire, and connecting it can cause problems - noise - induced from the non-shielded ground wire. In some situations you would ground all of your equipment, but that would be a real ground solution, including driving a 3'-6' copper rod into the ground - or tapping into the building ground system - but simply connecting all of your chassis with wire might bring about more noise problems with no ground "sync/drain" to bleed off the excess energy.
> 
> Also, if a cable has a built-in separate single wire ground wire I usually bend it back along the cable and tape it there so it doesn't "fly free" and touch metal causing problems.
> 
> The Dacmagic might have better noise prevention / isolation internally that the TA-26 doesn't, as my Topping A90/D90 also had a similar noise problem, so we need to fix the problem at the source so it doesn't get passed through our cables/devices.


thanks for answer !🙏
So i also bend it back along the cable and tape it


----------



## ProAcTivo (Feb 28, 2022)

Hi everybody.
I have the TA-26 for a month now and i absolutely love it paired with Sennheiser's HD600. Its a bliss! I now run the amp with a RCA NOS 6AS7G jan (1968) and a Tungsol 6SN7GTB new production.

I use Roon via Euphony OS (a linux OS designed for audio playback) with a slight variation of the Oratory Premium HIFI EQ profile for the HD600 engaged in the roon DSP engine.

DAC is a Loxjie D30 v1 (AKM chip)

Just beautiful sound!

In the next months i will buy one or two tubes to try (Shuguang Black Treasure and some Sylvania NOS)

P.S. Sometimes i heard some noise (static type) on my headphones . I managed to find that it came from the powerlines i was using. I switched to a mesh system and until now no more noise


----------



## kibot

Hello✌
i want to ask you about using mt-603 with S\N 100dB as a buffer between TA 26(with S\N 110dB and DACmagiplus ( with S\N112dB) - does it help with clipping??
Its almoust nice now when i use -11.5dB in APO EQ but i want to try back all WIN and EQ volume to 100%


----------



## Ufanco

Purchased a used Xduoo ta20 from reverb for $250 that included the stock tubes and a pair of Northern electric 12au7tubes.
Seemed a fair price since able to return it and having a limited warranty.
It will be replacing the Loxjie p20 and looking for best tube to be used with low independence iem’s (mest mkII) will be using a Shanling M6 pro 21 as source. 
Any suggestion for a good tube for this setup? Anyone using the northern electric tubes and are they any good?
I read thru the thread and thinking the Amperex but seeking other thoughts. Looking to spend around $70 or less.


----------



## hmscott (Mar 4, 2022)

Ufanco said:


> Purchased a used Xduoo ta20 from reverb for $250 that included the stock tubes and a pair of Northern electric 12au7tubes.
> Seemed a fair price since able to return it and having a limited warranty.
> It will be replacing the Loxjie p20 and looking for best tube to be used with low independence iem’s (mest mkII) will be using a Shanling M6 pro 21 as source.
> Any suggestion for a good tube for this setup? Anyone using the northern electric tubes and are they any good?
> I read thru the thread and thinking the Amperex but seeking other thoughts. Looking to spend around $70 or less.


Well, there are lots of nice tubes out there, but you don't need to worry about the IEM impedance, the output gain is handled by SS output, so the tubes don't "touch" the IEM's.  That is what makes the TA-20 a great headphone amp, the Hybrid Tube/SS design.

Those Northern Electric 12AU7's aren't cheap @ $47.50 each, and the reviews there look great )
https://www.thetubestore.com/northern-electric-12au7

Northern Electric 12AU7
​


----------



## Ufanco

hmscott said:


> Well, there are lots of nice tubes out there, but you don't need to worry about the IEM impedance, the output gain is handled by SS output, so the tubes don't "touch" the IEM's.  That is what makes the TA-20 a great headphone amp, the Hybrid Tube/SS design.
> 
> Those Northern Electric 12AU7's aren't cheap @ $47.50 each, and the reviews there look great )
> https://www.thetubestore.com/northern-electric-12au7
> ...




Thanks maybe it be best to stick with stock and the northern lights tubes for now. Making a list of ones that want to try in future many  more options than with Loxjie p20. Any suggestion are welcomed on tubes.
I just received the new 4.4 to xlr cable it sounds much better that the previous one did. It’s the DD ddHiFi DIY-XLR44A and also using the DD ddHiFi XLR44B to connect the 4.4 cables to xlr output. Happy so far with the DD ddHiFi items they seem good quality and don’t break the bank to buy.


----------



## YanaMJ

Ufanco said:


> Purchased a used Xduoo ta20 from reverb for $250 that included the stock tubes and a pair of Northern electric 12au7tubes.
> Seemed a fair price since able to return it and having a limited warranty.
> It will be replacing the Loxjie p20 and looking for best tube to be used with low independence iem’s (mest mkII) will be using a Shanling M6 pro 21 as source.
> Any suggestion for a good tube for this setup? Anyone using the northern electric tubes and are they any good?
> I read thru the thread and thinking the Amperex but seeking other thoughts. Looking to spend around $70 or less.


Mini watt


----------



## ostewart

TA-26 with RCA 6AS7G + Sylvania JAN VT-231 (6SN7GT)


----------



## ProAcTivo

Beautiful
What do you think of the Sylvania with that RCA? I have the same amp with RCA 6AS7G and Tungsol 6SN7GTB but i want to do some tune rolling


----------



## hmscott (Mar 8, 2022)

ostewart said:


> TA-26 with RCA 6AS7G + Sylvania JAN VT-231 (6SN7GT)





ProAcTivo said:


> Beautiful
> What do you think of the Sylvania with that RCA? I have the same amp with RCA 6AS7G and Tungsol 6SN7GTB but i want to do some tune rolling


Those are both great tube choices!  I've wanted to try a "GTB" as the VT-231's are "GT" "original" versions, and the "GTA" and "GTB" have different - higher rating - specifications.  I do have a Sylvania "Chrome Top" "Tall Boy" 6SN7GTA and it does sound different than the VT-231's, the "GTB" changes were smaller but I can imagine they sound still different again and I've seen reports they give better tighter Bass than the "GT/VT-231" series.

I've listened to the RCA JAN 6AS7G '50 + Sylvania VT-231, and found that is a great + consistant sounding combination, I have 3 of the VT-231's and they are very consistent in their sound as well - I do make sure to get new testing tubes - 2600/2600 or higher which is the expected readings for New tubes.

I've got 1 of the 1950 RCA JAN 6AS7G in brown box military packaging, and 1 of the Commercial Red box 1961 RCA 6AS7G, and there is a difference in sound between them, but the '50 is 100%/100% new while the '61 is only an estimated 85%/85%, so the difference in sound could be down to hours used.

What I'd found as my best combination so far was a 7236 Cetron (Tung-Sol) + '57 5692 CBS Hytron, both together provided the tightest Bass + Sweet Treble + Smooth Mid's.

That was my favorite combination until I swapped in a Melz '54 6N8S, and that really took the sound stage and clarity of sound to the best level so far, with plenty of tubiness.  I tried swapping the '50 RCA JAN 6AS7G with a '61 6H13C Svetlana but the 7236 really kicked up the Bass and complimented both the '54 Melz and '57 5692 Hytron.

From user reports the 7236 is an inexpensive 5998/421A, someday I may try the Tung-Sol (Chatham) 5998 Domino Plate or Westinghouse 421A, but it may be a long hunt as they are both rare and expensive.

My next tube(s) in a few months will likely be the Melz 1578, so I have a back up to that sweet '54 Melz. 

In these groups I found all I needed to know about which Makes, Models, Years, and details I needed to know to focus in on the best choices at the best price, and I'm sure appreciative of their kind help and assistance:
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008
https://www.head-fi.org/threads/6sn7-tube-addicts.479031/


----------



## ostewart

ProAcTivo said:


> Beautiful
> What do you think of the Sylvania with that RCA? I have the same amp with RCA 6AS7G and Tungsol 6SN7GTB but i want to do some tune rolling



I find the RCA to just sit there and do it's job, mine is from around 1960 and is really nice - detailed and smooth, just gets out of the way of the music.

The VT-231 however is quite detailed and crisp, changing from another Sylvania 6SN7GT I have (similar construction to the 6SN7WGT) I noticed a tighter and more controlled sound, especially in the bass. It doesn't have that velvety tube warmth some love, however it is still a natural sounding tube, just one that is cleaner than a lot I have tried. 

I got it for really cheap, I don't know how well used it is, but it works perfectly in my amp.


----------



## hmscott (Mar 9, 2022)

It did seem like the 6AS7G position didn't make much difference - 2 6AS7G and 4 6H13C, until I tried a 7236 variant, then there was a big difference 

There are a few Sylvania 7236 pairs on eBay right now for $40/tube in pairs - I've successfull negotiated a single tube purchase 4 out of 5 times, it might be worth asking the seller if they have a single 7236 available for sale.

*Warning Update: It looks like the Sylvania 7236's aren't actually a "real" 7236, some think they are Sylvania 6080's relabeled as 7236's as they don't sound any different than Sylvania 6080's.  I'm going to stick with the Tung-Sol/Cetron 7236's myself.*

I paid $59 for my single NOS Cetron 7236:
NOS VINTAGE TUNG SOL CETRON 7236 5998 TUBE WOO HEADAMPS PAIRS AVAILABLE

And, over time I've seen that is about the right price - $40-$50/tube in a pair - but also some go for much more - there are a Tung-Sol 7236 and Sylvania 7236 auctions going with $108 as a "buy it now" from the same seller:
https://www.ebay.com/itm/284673358577?hash=item4247dabaf1:g:VisAAOSwuThfyY0e
https://www.ebay.com/itm/284673358504?hash=item4247dabaa8:g:SH0AAOSwPjxfxvRL

I waited until there was a NIB 7236 tube for the right price, and I am very happy I did get mine, it is an amazing sounding upgrade from the 6AS7G - I'll be hunting for another.  BTW, I've heard that all of the 7236 tubes were made by Tung-Sol who was later bought by Cetron:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=7236+tube&_sacat=0

The list of 6AS7G variants in this post was very helpful, with the 7236, 5998, 421A the top compatible variants that reports say make a big difference:
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

The only 2 steps up would require verifying by Xduoo that the TA-26 could handle the doubled current draw:
*6528 - equiv to 5998 but very high gain at 9, twice the current load. Make sure you amp can handle it
6336 - like 6528 but low gain at 2, still twice current load. Make sure you amp can handle it*

I've asked Xduoo directly about that question, if those particular tubes can be safely used in the TA-26, but Xduoo haven't tried them and couldn't answer to their specific support in the TA-26.  I've thought about getting a couple and sending them to Xduoo with the warnings about what to expect - specification sheets and links to others reports of modifications needed in other amplifiers.  But, for now I'm happy with what I've got, and will suggest someone else might want to take up the baton and try this with Xduoo themselves.

Recently I've found reports of use of an even rarer variant, not on the list, and it does sound compatible and promising:
Tung Sol 7802 - https://frank.pocnet.net/sheets/077/7/7802.pdf

The 7208 has been reported to work in amps similar to the TA-26 without modification, and by others with a small mod to avoid self-oscillation due to 20,000 mho of 7208 vs "standard" values of 1/3 (6AS7G)- 1/2 (5998/421A/7236);
https://forum.bottlehead.com/index.php?topic=3664.0

One sold back in December on eBay:
https://www.ebay.com/sch/i.html?_from=R40&_nkw=Tung+Sol+7802&_sacat=0&rt=nc&LH_Sold=1&LH_Complete=1
https://www.ebay.com/itm/324959603962?hash=item4ba91a0cfa:g:YAAAAOSw8mJhxoGv&nma=true&si=RlLfpB3BERKYRO376Ku9L2kwQts%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557



That eBay 7208 product description reminds me that I am also looking for a _*NIB Bendix 6080WB*_ (*also here*) with Large Graphite Plates and thick Ceramic Spacers as described here:
"Extremely scarce Tung-Sol 7802WB tube, labeled for Lewis & Kaufman, with original box. This is the only one of these that I've had in decades of tube collecting. Often used in place of the 6AS7 and 6080 in headphone amps. This is the "WB" version, which like its 6080WB counterpart, is made with warp-proof graphite plates, ceramic spacers, heavy glass, and other features that result in a very durable tube. Excellent balance between sections"

Check out the innards of that 7208, the crazy coating on the plates, the triple thick ceramic spacers instead of Mica, the thick copper rods, and the thick glass... one awesome looking tube:

Here is a Bendix 6080WB which has similar construction:
https://www.ebay.co.uk/itm/Bendix-Matched-Pair-CEA-6080WB-Tubes-Carbon-Plate-3-Mica-039-s-Excellent-NOS-6080-wb-/304193734092?hash=item46d35c05cc:g:yk4AAOSwJSthcRm9&nma=true&si=vwB3EKVpYaB6f10cNOM9uOs9pWs%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557


I think I'll buy another 7236, maybe a Tung-Sol labeled to see if they sound different than the Cetron 7236...it really does change the sound of the TA-26, similar as described in that 6AS7G variant list:
*7236 - medium gain - great bass, fast and dynamic. Almost SS sounding

The Cetron (Tung-Sol) 7236 adds back a little of the SS sharpness, focus, and adds powerful impact, while giving that wide stage eufonic sound I love.  

Warning Update: **It looks like the Sylvania 7236's aren't actually a "real" 7236**, some think they are Sylvania 6080's relabeled as 7236's as they don't sound any different than Sylvania 6080's.  I'm going to stick with the Tung-Sol/Cetron 7236's myself.*


----------



## albertmuc

In the "xDuoo TA-20" I like the "TAD 12AU7A / ECC82" best so far, the sound is clean and detailed, nothing disturbs, on top of that it can be bought new and cheap. 

With the "RFT foil getter" I got the feeling of an annoying freshness, but have to switch back to it to verify it.  While the "Gold Lion 12AU7 / ECC82 Genalex" sounds too harmonically-soft and not sufficiently clean.


----------



## YanaMJ

With my TA-20, I've tried JJ gold, Sylvania green label of the 50's, TAD, Brimar Uk and Philips Miniwatt Heerlen code delta. 

I prefer the Philips without any comparison.


----------



## hmscott (Mar 9, 2022)

albertmuc said:


> In the "xDuoo TA-20" I like the "TAD 12AU7A / ECC82" best so far, the sound is clean and detailed, nothing disturbs, on top of that it can be bought new and cheap.
> 
> With the "RFT foil getter" I got the feeling of an annoying freshness, but have to switch back to it to verify it.  While the "Gold Lion 12AU7 / ECC82 Genalex" sounds too harmonically-soft and not sufficiently clean.


I've heard others enjoy the TAD tubes as well 

And, I've had the same experience with the modern expressions of famous NOS tubes.  The Genalex was an ok tube, none of them were offensive, just not verying exciting - they didn't stir my emotions.  Same went the Harmonix, modern Mullard, modern Telefunken, JJ, etc.

TAD also has a few other interesting tubes that might be worth trying, I've wanted to try another 12AX7 - the 7025, and my favorite for the TA-20 - a 12AT7:

7025 WA TAD HIGHGRADE Premium Selected
https://www.tubeampdoctor.com/7025-wa-tad-highgrade-premium-selected

12AT7 / ECC81 TAD Premium Selected (symmetrisch/balanced)
https://www.tubeampdoctor.com/12at7/ecc81-tad-premium-selected-symmetrisch/balanced

And, TAD has a 6SN7 too at a good price:

6SN7GT TAD Premium Selected
https://www.tubeampdoctor.com/6sn7gt-tad-premium-selected

I wonder what the original source was for these TAD tubes?  NOS TAD tubes - the comments go back a ways...and TAD have good prices on other brands too 


YanaMJ said:


> With my TA-20, I've tried JJ gold, Sylvania green label of the 50's, TAD, Brimar Uk and Philips Miniwatt Heerlen code delta.
> 
> I prefer the Philips without any comparison.


I found similarly, the best were Amperex Philips Heerlen Holland E180CC Pinched Waist tubes, unfortunately they were microphonic, which wasn't so bad - I was able to work around it, but then they developed a static noise that would hit randomly.  I've sent them back to get another pair reselected, I hope he can find a pair that don't exhibit that noise, as they were the best sounding tubes for me in the TA-20:

NOS NIB PHILIPS HOLLAND PINCHED WAIST D FOIL GETTER E180CC 7062 12AT7 E81CC


Fortunately I have a matched pair, plus 3 spares, of these Mullards made in Heerlen Holland, which are a close 2nd:

Matched Pair E180CC NOS Mullard Holland Valve Tubes

Unmatched they are a good bit cheaper: E180CC 5965 12AV7 NOS Mullard Holland Valve Tubes

The Heerlen Holland factory made tubes have all been great sounding tubes


----------



## ProAcTivo

Thak you all for the replies. Apreciated.
The CBS must be awesome but is quite expensive... maybe i will go the Melz route as it is more afordable.. 
To be honest, i dont want to enter the spiral of tuberolling.. about one year ago i start to mess with EQ with my HD600 and since then i found that the most differences i was able to achieve was via EQ. 
The addition os the TA-26 was the cherry on top. The sound i already had with EQ needed more power and more bass and sub bass (via eq was not possible to get more without messing up the sound) and the TA-26 gives exactly that. Im very sensitive with high frequencies so the sound is perfect now in that regard. But i do miss some more clarity in the mids(just a hint more) so maybe one of those tubes will bring me that 😉


----------



## albertmuc (Mar 9, 2022)

hmscott said:


> 12AT7 / ECC81 TAD Premium Selected (symmetrisch/balanced)
> https://www.tubeampdoctor.com/12at7/ecc81-tad-premium-selected-symmetrisch/balanced


Actually I wanted to stop testing, but if you really mean the 12AT7 technically fits in the TA-20…

Edit: just reading: „This article is no longer available“, but a „ECC81 / 12AT7-Cz“… 🤔


----------



## hmscott (Mar 9, 2022)

ProAcTivo said:


> Thak you all for the replies. Apreciated.
> The CBS must be awesome but is quite expensive... maybe i will go the Melz route as it is more afordable..
> To be honest, i dont want to enter the spiral of tuberolling.. about one year ago i start to mess with EQ with my HD600 and since then i found that the most differences i was able to achieve was via EQ.
> The addition os the TA-26 was the cherry on top. The sound i already had with EQ needed more power and more bass and sub bass (via eq was not possible to get more without messing up the sound) and the TA-26 gives exactly that. Im very sensitive with high frequencies so the sound is perfect now in that regard. But i do miss some more clarity in the mids(just a hint more) so maybe one of those tubes will bring me that 😉


Yup, EQ can take you the rest of the way, but a good base sound is required to start with 

I'm not using EQ, my headphones / IEM's sound different from each other and I do enjoy the variation, plus my ability to EQ differs with each source, with some not providing any EQ capability.

And, I agree, the missing component was a balance between euphonic sound and the sharp clarity of SS, which is why I enjoy the TA-20, but the TA-26 as tube only for me needed tubes that would bring out the best of both SS and Tube sound.

For me the Tung-Sol/Cetron 7236 is inexpensive enough if I waited for a good price to be listed, otherise for about 2x that best price there are more often choices available.

I haven't spent enough time running through all my 6SN7 variants against the 7236, but at least my previous 2 best sounding really blossom with the 7236.  The CBS-Hytron JAN 5692 is probably more available now than the Melz - given the outbreak of war in Ukraine - my '54 Melz came from Ukraine, and the '53 came from Russia, it may be a while before we see those again.


----------



## hmscott (Mar 9, 2022)

albertmuc said:


> Actually I wanted to stop testing, but if you really mean the 12AT7 technically fits in the TA-20…
> 
> Edit: just reading: „This article is no longer available“


Ah, I should have translated before posting 

Fortunately there are other listings for each tube type, here is another TAD 12AT7 that doesn't say "...no longer available":

ECC81 / 12AT7-Cz TAD Premium Selected (symmetrical/balanced)
https://www.tubeampdoctor.com/ecc81/12at7-cz-tad-premium-selected-symmetrisch/balanced

There are other 12AT7 listings:
https://www.tubeampdoctor.com/search?sSearch=12AT7

Also, yes I confirmed with Xduoo that the TA-20 supports other variants:  12AU7 (ECC80), 12AT7 (ECC81), 12AX7 (ECC83) (too hot sounding), and afterwards I confirmed these also work great: 6060, M8162, E80CC, E180CC, and more.

For me the 12AT7, 6060, M8162, E80CC, E180CC sounded best as compared to the 12AU7 tubes I found, until I ran into 12AU7's made on Telefunken equipment, but those are even harder to find than NOS Telefunken tubes.

If you are happy with what you have, I'd stick with that for a while.  Let them burn-in and they might even sound better


----------



## ProAcTivo

hmscott said:


> Yup, EQ can take you the rest of the way, but a good base sound is required to start with
> 
> I'm not using EQ, my headphones / IEM's sound different from each other and I do enjoy the variation, plus my ability to EQ differs with each source, with some not providing any EQ capability.
> 
> ...


The RCA CBS JAN 5692 is the same as CBS Hytron?


----------



## hmscott (Mar 9, 2022)

ProAcTivo said:


> The RCA CBS JAN 5692 is the same as CBS Hytron?


Thank you for catching that 

I fixed it, "CBS-Hytron JAN 5692", and if you look at the photo/link - printed on the box: "MFG by CBS-HYTRON", the Brown Base only says "CBS".

There is a lot of "lore" out there about the 5692.  RCA did make the first Brown Base 5692's in 194[8-9], but after that there are differing generalizations I've found.  I'll link a few of the descriptions I think converge into a single narrative.

In general ( no pun intended ), I had originally heard RCA made the first 5692's, relabeled for everyone during the 50's, and then from '60 on General Electric made them with Red Bases, and supposedly those didn't sound quite as good as the RCA originals.  I haven't heard a GE Red Base or Original RCA Brown Base.

The CBS Hytron's were made by them, not by RCA or GE, and are said by some to sound better than the original RCA or GE 5692's, which is why I went looking for them.  I was fortunate to find a CBS JAN labeled 5692 at a great price, but there are also *rebranded Zalytron relabeled CBS-Hytron originals* which are less expensive.

I don't have the original links that I first read, I might have posted them - please check my previous posts -  but googling again, I found these new descriptions that fit what i first learned, this is a good first summary:* (Update: I've included the link to the 1st 5692 info I found)*

The facts on the 5692
https://www.audioasylum.com/audio/tubes/messages/5/59869.html

"The original 5692 was introduced by RCA in 1949. RCA red base 5692 were never manufactured by RCA, they were built under contract by General Electric. General Electric branded 5692 red base tubes are also quite common, are identical of course to the RCA's, and generally sell for less.

But it is not correct that CBS-Hytron, Tungsol, and Raytheon branded 5692's are the same as the RCA/GE. They are not. CBS-Hytron manufactured their own 5692, as did Raytheon and Sylvania. They look virtually identical to the RCA/GE except for the brown base. Standard Electric of Sweden also made the 5692 usually labelled 33S30, and it is by far the best sounding - but impossible to find.

The CBS-Hytron is thought by most to be quite superior to the RCA in that is has better bass and less roll-off on top. The Raytheon has a slight, almost undetectable construction difference, is impossible to find, and actually sounds better than the CBS. But beware of Raytheon labelled 5692's as they stopped producing them in the early 60's, then were re-labelling other peoples."

Ahh, I found my original "source", right here on head-fi.org 

The Reference 6SN7 Thread - well down into the post are the 5692 detailed descriptions, re-quoted below as a "spoiler"
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-1380036


Spoiler: Re-quoted here for your convenience:



*- 4. 5692 TYPE TUBES*

An interesting anecdote: the 5692 type tube was first developed by RCA (but RCA never actually _made_ them!) after the US Army Artillery Corps requested a tube that could stand up to the _immense_ trauma that came with repeated firing. Apparently, large field pieces would chew through tubes in no time

5692s are characterised by their extremely-short bottle form factor, vastly oversized plates and extremely liberal use of support posts. Almost all 5692s have small top getters and double micas on top.

*Fact 1:* The 5692 was patented in 1949, but was not produced en masse till around 1951. Hence this would imply that there is no such thing as a 1940s 5692. 

*Fact 2:* The widely advertised of ‘10000 hrs life’ for the 5692 is just advertising baloney. If one would observe carefully, the 5692’s specs differ quite greatly from the 6SN7s – far lower plate voltage and max dissipation rates are given. It can be inferred that this conservatism in its ratings contributes directly to the 5692’s purported long life. Hence, if you intend to use the 5692 as a drop-in for a 6SN7 in an amp running 6SN7 voltages and currents, be prepared to have your 5692 last no longer than a normal 6SN7 at best.

*Fact 3:* By the late 1960s, tube manufacturers were relabelling tubes willy-nilly in an attempt to minimise their losses in what was essentially a dying market. There are many instances of 6SN7GTBs/WGTs/ being labelled as 5692s and passed on to the market. The vice-versa applied too; 5692s were relabelled as other 6SN7 types. Hence when verifying potential 5692 purchases look out for the 5 extraneous free-standing (ie. not attached to a grid/plate) support posts.

*Fact 4:* Only 3 American companies are definitely known to have made 5692s – General Electric (“RCA” 5692s were made by GE) [red bases – colour varies from a cherry-red to a deep red easily confused with brown], CBS/Hytron [brown bases] and Sylvania [black bases]. Raytheon purportedly made a small batch of brown-based 5692 [the CK5692 – apparently the mica shape was slightly different from normal CBS/Hytrons], but as CBS/Hytrons were _known_ to be relabelled as Raytheons, this remains a mystery. *If you know the answer to this, let me know...

Fact 5:* There is only one known non-American make of this tube: Swedish Standard Electric 33S30, which can be distinguished by the micas and the plates always having a serial number scratched on.

_*5692, CBS-Hytron 
[black plates, top getter, brown base] [known to be relabelled as Raytheon 5692 and Raytheon 6SN7WGT]
● “Fast, good dynamics, lot of air and great timbre” –Chimera
● “WOW!! this is one of the incredible tube swaps I have ever done. This tube improved everything greatly. amazing improvements in detail, imaging, soundstage depth and bass tautness.” –Tuberoller*_
*● “The RCA or CBS 5692 is a good tube, but doesn't get to the top of the list. It has much weaker bass, is very nice tonally, and the highs are a bit recessed.” –Robert H*

*5692, RCA Red Base (made by GE)*
_[grey plates, top getter, red base, 1950s vintage - white labels, 1960s vintage - orange labels] [known to be relabelled as GE 5692]_
● “Very warm sweet sound, great on voices and jazz” –Chimera
● "RCA 5692 red base. I finally found out why people like this tube. It hasn't sounded good in any other 6SN7 amp I've used. In the Wheatfield, it's got plenty of detail and a nice "lush" tubey sound." -Hirsch [in _Tuberolling the Wheatfield HA2_ thread]
● "Warm. Lush. Romantic - these words spring to mind immediately. Better air than even the TS RP. Seperation and detail are on par with the best of them imo. Slightly tubby bass. Good impact. Amazing with jazz and pianos. Never harsh sounding." -adhoc
● ”The RCA or CBS 5692 is a good tube, but doesn't get to the top of the list. It has much weaker bass, is very nice tonally, and the highs are a bit recessed.” –Robert H

*5692, Sylvania*
_[black base, top getter, yellow 'Sylvania' label on glass] [RUMOURED TO BE RELABELLED Syl 6SN7GTBs. BEWARE!                                                    _

● “5692, Sylvania, very fast , good bass and dynamics, lot of air and great timbre. My favorite tube in my current system.” -scottpaul_iu
● “All the black base Syl 5692's I've seen are rebranded GTB'S - THEY DON'T EVEN LOOK LIKE 5692'S! But there are real Sylvania 5692's that have the 5692 construction and brown bases, these are the ones I suspect the comment refers to. It's interesting that such an ordinary sounding tube caught on in such a big way with some audiophiles despite it's poor sonics. It first came to attention in the 1980's when the 6SL7 version, the 5691, was used in an MFA preamp. The 5691's good performance in that unit and it's cool red base caught the interest of some 6SN7 users, particularly in the Orient - where most of the MFA production was sold, hence where the buzz first caught on. The 5692 then started to get a bit of circulation, at which point Peter Qvortrup of Audio Note UK had amassed a sizeable stash of them and, finding he could get outrageously high prices for them from his bespoke customers due to their rarity and the unique red bases, proclaimed them "the best" - conveniently to support the prices he was charging. It all caught on from there and, like so much of audio, has no bearing to reality.” –Robert H. (in personal correspondence)
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-1380036



I started learning about the history of the 5692 mere months ago, and I hunted down this CBS JAN 5692's a few times until I found this '57 CBS JAN 5692 that I thought was at a good price, $148.88:

CBS JAN CHY 5692 6SN7 VACUUM TUBE SINGLE BLACK PLATE NOS ORIGINAL BOX
https://www.ebay.com/itm/325008104909



Here are the current going prices for CBS JAN 5692s:
https://www.ebay.com/sch/i.html?_from=R40&_nkw=CBS+JAN+CHY+5692&_sacat=0&_sop=15

And, the Zalytron 5692's, rebranded CBS-Hytron 5692's:
https://www.ebay.com/sch/i.html?_from=R40&_nkw=5692+Zalytron&_sacat=0&_sop=15

*Update: Upscale Audio has a listing for the Zalytron 6SN7GTB which is a relabeled CBS-Hytron 5692 - look at the photo's you can see the same posts and spacers as in the 5692, but if you read further in the description they may fulfill the order with:*

"These are a matched set made by G.E., RCA, and CBS. This is the CBS, my personal fav. CBS 5692 throw a deep soundstage. They are easy to identify by the extra support rods and extra mica spacer. No other tube was built like the legendary 5692. The tubes are marked as 6SN7 Zalytron. Zalytron was a tube re-seller, not a manufacturer."

I would ask exactly what they are sending before buying, and I would ask for photo's of the tube(s), boxes, and the full measurements output from their Amplitrex(es) or whatever they used for testing these tubes, otherwise you may not be happy with what they do send you:

CBS HYTRON 5692 / 6SN7 Rebranded ZALTRON
https://www.ebay.com/itm/304388098129

And, until the Melz's came along I prefered the 5692 over any of the very nice VT-231's, Sylvania's + Kenrad.

I think the sound from the 5692+7236 is very enjoyable, and before that the '50 RCA JAN 6AS7G + CBS JAN 5692 was my favorite sound too:

Jan RCA 6AS7G Military Audio Radio Vintage Tube NOS 1950s
https://www.ebay.com/itm/275069376271


But, please remember, I am only learning this all recently, while there are many experts here on head-fi.org with decades of experience, so I found it was a good idea to read up on the threads here for a good long while before ordering my own tubes to try.

*Update: The same seller I bought my '57 CBS-Hytron JAN 5692 from has a pair of them for sale, perhaps he'd take an offer?  IDK if he would split the pair though you could ask:*

CBS JAN CHY 5692 6SN7 VACUUM TUBE DATE MATCHED PAIR BLACK PLATE NOS ORIGINAL BOX - $398.88
https://www.ebay.com/itm/224847906799


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## ProAcTivo

hmscott said:


> Thank you for catching that
> 
> I fixed it, "CBS-Hytron JAN 5692", and if you look at the photo/link - printed on the box: "MFG by CBS-HYTRON", the Brown Base only says "CBS".
> 
> ...


Thank you for all your insights. Really helpful!! Unfortunatly i cannot buy from the US. Im on Europe and i dont want to handle with customs duties (its a nightmare)..
I have to buy within Europe..


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## hmscott (Mar 9, 2022)

ProAcTivo said:


> Thank you for all your insights. Really helpful!! Unfortunatly i cannot buy from the US. Im on Europe and i dont want to handle with customs duties (its a nightmare)..
> I have to buy within Europe..


Do you use the local eBay site in your country?, or in the next country over?  All you would need to do is "replace the domain suffix" in the links I've been posting from eBay.com and that URL - the same "itm" number - will work in that country!


Spoiler: Examples...



Here are a couple of examples of viewing the same eBay item in several different host countries:

US URL: https://www.ebay.com/itm/224847906799

Canada URL: https://www.ebay.ca/itm/224847906799

UK URL: https://www.ebay.co.uk/itm/224847906799

Italy URL: https://www.ebay.it/itm/224847906799

Spain URL: https://www.ebay.es/itm/224847906799

What is your country's local eBay URL? - what is that domain suffix?  Substitute the .com in the URL I post for your eBay domain suffix (extension), and you can see the same eBay Item on your eBay!

I use this in reverse to look at the "Other items" in foreign (to US) eBay stores.  If I search for an item type in the US eBay, I occasionally get an .es or .co.uk, or .it sellers item, but if I go to their store "see other items" link from the US more often than not I see nothing else.  So, I find out what country they posted the item I found from, substitute the eBay link .com with their countries domain suffix, and then I login - Yes! you can login to foreign eBay sites with your home country username/password, and you can even maintain a separate cart in that country - then I can click their native item "show other items" link and see everything in their home store!  Pretty cool stuff 

So, hopefully it is very easy to buy through your local country eBay - as easy as eBay can make it in each host country.

I do understand that might not matter in some countries for ordering items from other countries - even with eBay's help - but it is worth checking out and talking to eBay support in your home country - or the closest one to your country if there is no native support.

I know that was a lot of stuff, but in essence the eBay listing item numbers are unique across the world, so whereever you are you have a good chance of buying from anywhere.  There are some sellers that won't want to offer shipping to other countries, and so you can check the option box in eBay search to limit the region for finding items, or open it up to other countries specifically.

And, you can search for the items I post in your local country eBay and find equivalent items located in local countries that won't cost you too much to "import" from local countries too.

PS: You can list your home location in your head-fi.org profile so we can see it in your Posts - top right corner of each Post.


I hope this explanation helps someone, good luck


----------



## ProAcTivo

hmscott said:


> Do you use the local eBay site in your country, or in the next country over?  All you would need to do is "replace the domain suffix" in the links I've been posting about eBay.com and that URL - the same "itm" number - will work in that country!  And, I haven't done it myself, but I've talked to others purchase through eBay in their country and eBay handles the shipping/customs details for the seller and the buyer.  Something to look in to.
> 
> Here are a couple of examples:
> 
> ...


Thank you for your comprehensive reply. I understand everything. I know i can buy from everywhere in the world as long as the buyer sends it to Portugal. The problem is that the tubes will come from the US so when they arrive in Portugal it has to pass through the country customs and then they will ask me how much i paid for the item. Then they will charge 2 or 3 fees more and only when i pay them the tubes will be delivered to me. I bought items from the US before (and other countries ouside EU) and it was really bad. If i buy a tube for 100$ in the end it will cost me at least 150$ besides the delays and bureaucracy. (If the item lands on the hands of DHL the price is even higher) 

On the other hand, if i buy from someone in Europe i pay to the seller and the item will be delivered to me with no worries. 

So its that. I know im limited on my options but i prefer to buy safe and easy. For some tubes is better. Melz for example are avaible from wertern europe countries.. but the 7236 is not ;(


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## hmscott (Mar 9, 2022)

Spoiler: for ProActivo






ProAcTivo said:


> Thank you for your comprehensive reply. I understand everything. I know i can buy from everywhere in the world as long as the buyer sends it to Portugal. The problem is that the tubes will come from the US so when they arrive in Portugal it has to pass through the country customs and then they will ask me how much i paid for the item. Then they will charge 2 or 3 fees more and only when i pay them the tubes will be delivered to me. I bought items from the US before (and other countries ouside EU) and it was really bad. If i buy a tube for 100$ in the end it will cost me at least 150$ besides the delays and bureaucracy. (If the item lands on the hands of DHL the price is even higher)
> 
> On the other hand, if i buy from someone in Europe i pay to the seller and the item will be delivered to me with no worries.
> 
> So its that. I know im limited on my options but i prefer to buy safe and easy. For some tubes is better. Melz for example are avaible from wertern europe countries.. but the 7236 is not ;(


That is too bad, I wish there were a better solution...perhaps someone in your country knows a way to accomplish this for less cost and hassle?

I did search in "European Union", and also searched within a couple of other host countries, and there is little to zero items for a number of these tubes available.  They only come from the US, UK, Russia, Ukraine, etc - all non-European Union sources.

So, it is the only choice to "weather" customs and bureaucracies.  Perhaps there is a local service to streamline such purchases to take some of the load off of you? - except they'd probably add another charge there too.  At least a service would save you the daily hassles monitoring your packages.  For me, I enjoy that part of it too. Tracking packages gave me something to do during the pandemic lockdowns.

Well, sometimes if we really want something we have to get out of our normal comfort zone to get them, maybe even pay a little more...a good incentive to find the best priced items for sale.  The Delta between what I bought for vs the median/top prices was pretty large, certainly 25%->50% and more, so you could "make up" the customs fees by shopping diligently for the best deals.

A lot of eBay sellers regularly offer discounts of 5%-25% and more via store sales, so watch for those too.  I spent days and weeks looking for some of the tubes I found, and scheduled some purchase out a month or more when I found some of them.

Hey, what about audio amplifier builders in your country?  Or, even general electronics manufacturing?  Maybe they have figured out how to import parts and you can ask them to order tubes for you cheaper?  Or, at least with less hassle?

Anyway, I'm sure you'll figure out some way to get what you need, and I hope you do 


On more than one occasion I've looked for European / other overseas Tube sellers outside of eBay, and every time they are a disappointment - very few NOS tubes are listed.  So I do feel your pain. 

You never know what you are going to find until you look, but sorry to say this is also a US company, Wisconsin to be precise...

Power Tubes
https://tubeworldexpress.com/
https://tubeworldexpress.com/collections/power-tubes/7236 3 in stock
https://tubeworldexpress.com/products/jan-7236-cetron-nos-1983-100ma-130ma-tungsol-clone <= best of the 3 in stock
https://tubeworldexpress.com/collections/power-tubes/6AS7G <= cheap!
https://tubeworldexpress.com/collections/power-tubes/6080 <= cheap!
https://tubeworldexpress.com/products/421a-western-electric-low-hours-like-new-1965 <= out of stock 
https://tubeworldexpress.com/search?q=Western+Electric

They have a few 7236's listed, a few 6AS7G's, and a bunch of 6080's, and lots of other tubes in inventory - check out the tube list dropdowns!, has anyone done business with them?

And, I actually found these a few days ago, but they are coming from Germany so they are available without customs for you @ProAcTivo ?  Check out the thick ceramic plates and hefty rods and glass, pretty awesome.  Not cheap, but then no wasted money on customs either:

RAYTHEON 6080 WB Graphite Röhre Tube Valve NIB NOS „GUT“ #1
https://www.ebay.co.uk/itm/373963511654

RAYTHEON 6080 WB Graphite Röhre Tube Valve NIB NOS „GUT“ #2
https://www.ebay.co.uk/itm/373963516896

IDK the seller, but they have 100% rep and "enough" transactions to give them a shot.  IDK if the tube is too expensive, and I've never tried that particular tube, but it has a good reputation.  If you do get one, please do let us know how it works out


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## hmscott

A review of the TA-26, he goes a bit into affordable tube rolling too 

xDuoo TA-26 OTL Tube Amp Review - Tuuuuuubes!
​


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## ProAcTivo

hmscott said:


> Spoiler: for ProActivo
> 
> 
> 
> ...


I have the oportunity to buy a Dumont 6SN7WGT(new) a RAYTHEON JAN-CRP-6SN7WGT and a RCA 6SN7GT(new). Each for 40€. Wich one do you think is the best? Is it a fair price? Thank yoy


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## hmscott (Mar 10, 2022)

ProAcTivo said:


> I have the oportunity to buy a Dumont 6SN7WGT(new) a RAYTHEON JAN-CRP-6SN7WGT and a RCA 6SN7GT(new). Each for 40€. Wich one do you think is the best? Is it a fair price? Thank yoy


To me those seem like low prices for new/NIB/NOS GT/WGT tubes.  What do you know about the seller?  Is he giving you a deal for some reason?

I haven't A/B'd a GT vs WGT, in fact I've only done that for 3x GT's and 1x GTA, and to me all the GT's sounded the same while the GTA sound better to me in my AMP.

You may have been fortunate to find actual New tubes for $40 each, and if so I'd buy all 3 and try them out to see if I liked them.

That is how you build up experience to know what you enjoy.  I or someone else might enjoy different sound characteristics.

Also, I've found it helpful to download the specifications sheets for tubes, each variation may require changes to the design of the amp to get the best out of them.  The TA-26 wasn't designed with the high plate voltage allowed by the GTA/GTB, so the older designs won't be overdriven.

Even if it isn't required for operation, it is nice to know what changed between name suffixes so we can start to attribute what changes made what differences in sound to our ears - if that is possible.

Yeah, I'd definately buy all 3 if I trusted the seller.  But if I didn't know the seller I'd ask a bunch of intelligent questions to see how he/she answers - and gradually build up trust in both directions if it doesn't already exist, and then maybe buy 1 not too expensive of a tube first to see how the transaction goes - as long as you two interact well for the intial questions.

I'm happy for you that you found some NOS tubes "New" for such a great price


----------



## ProAcTivo

hmscott said:


> To me those seem like low prices for new/NIB/NOS GT/WGT tubes.  What do you know about the seller?  Is he giving you a deal for some reason?
> 
> I haven't A/B'd a GT vs WGT, in fact I've only done that for 3x GT's and 1x GTA, and to me all the GT's sounded the same while the GTA sound better to me in my AMP.
> 
> ...


Thank you for your help! I have to buy you a coffee some day. 
I think o will buy only one first. Maybe the DUMONT because its new and is identical to the Raytheon.. i think they are both Sylvania rebranded...at least the Sylvanias are very identical and i read somewhere that they rebranded the 6SN7WGT to others..


----------



## Ufanco

Bought some inexpensive tubes to try out in the Xduoo ta20. Really enjoying the sound quality of this amp so going keep it and try to sell the Loxjie p20. 
Going be a fun weekend trying out the tubes I bought. Tubes going try out are a pair of Matched RCA CLEAR TOP Gray Plate Side D Getter and pair CONN by Westinghouse Long Black Plate D Getter. 
Hopefully they sound a least as good as the northern electric 12au7. Thought they sounded good but need to hear some others before commenting on them.


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## hmscott (Mar 10, 2022)

ProAcTivo said:


> I have the oportunity to buy a Dumont 6SN7WGT(new) a RAYTHEON JAN-CRP-6SN7WGT and a RCA 6SN7GT(new). Each for 40€. Wich one do you think is the best? Is it a fair price? Thank yoy





ProAcTivo said:


> Thank you for your help! I have to buy you a coffee some day.
> I think o will buy only one first. Maybe the DUMONT because its new and is identical to the Raytheon.. i think they are both Sylvania rebranded...at least the Sylvanias are very identical and i read somewhere that they rebranded the 6SN7WGT to others..


Sounds good 

Here is some info about the 6SN7WGT place in tube history, there are likely many other recollections, I've found it a good idea to keep looking and reading to get some kind of cross check on the details 

*"6SN7WGT* *- Military version of the 6SN7GT; 10,000hrs minimum life (up for debate). _“IMO, while tubes (like car engines or light bulbs) may be rated for a specific lifetime, a LOT depends on the actual usage type and pattern the tube will see. E.g. Switch your amp on/off 10 times a day? Don’t expect 10,000hrs.”_ -Author
*6SN7WGTA* *- Military version of 6SN7GTA.
*6SN7WGTB* *- Military version of 6SN7GTB."

There are more citations and comments about the 6SN7WGT throughout that post...
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-1380036

The 6SN7GT – the best general-purpose dual triode?
https://www.effectrode.com/knowledge-base/the-6sn7gt-the-best-general-purpose-dual-triode/

"One of the first military types was Sylvania’s 6SN7W with its unique metal shell base. (Note the lack of “GT”!) This had a stiffening rod added to the otherwise conventional structure. By the mid-1950s, most tube manufacturers made a 6SN7WGT type with the extra stiffening and often thicker micas, as well as a low-loss micanol base. The last versions were basically receiving tube construction that were tested and sorted to tighter specifications..."

"...The 6SN7GTB continued in high production in America as a replacement tube. As the tube companies started dropping out one-by-one, production was concentrated in fewer factories. The last known American production was the 6SN7WGTA by Philips ECG (formerly Sylvania) in 1986."


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## hmscott (Mar 12, 2022)

FYI - I found an eBay seller from Ukraine, and he is still online and his location still has International Shipping - he's got some cool tubes (Melz, 6S8N) and other interesting antique tube and audio stuff, more info here:
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-16859367


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## hmscott (Mar 12, 2022)

Great news, per Xduoo response below, the TA-26 can easily handle the 950mA heater current of the NOS Mullard ECC32/CV181.  Normal 6SN7 tubes draw 600mA.

The modern Chinese CV181-? models are actually 6SN7 designs, and are not at all related to the original Mullard ECC32/CV181 design specifications.  So the modern Chinese CV181-? tubes are also compatible with the TA-26.

I asked Hifigo.com / Xduoo.com (service@hifigo.com and service@xduoo.com ) specifically about the Mullard CV181 which draws 950mA heater current vs 600mA:
The question I sent through Hifigo: https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-16857775
Answer direct from Xduoo: https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-16860831

From service@xduoo.com to service@hifigo.com, me - Mar 11, 2022, 10:20 PM (13 hours ago)

"Hi,
*No problem, the TA-26 maximum heater current is 4A*
Best Regards,"

*Unfortunately, these power tubes draw 5A heater current, well over the TA-26 maximum of 4A:*

6528 - equiv to 5998 but very high gain at 9, twice the current load. Make sure you amp can handle it
6336 - like 6528 but low gain at 2, still twice current load. Make sure you amp can handle it
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

*They are available on eBay, but are not compatible with the TA-26*
6336: https://www.ebay.com/sch/i.html?_from=R40&_nkw=6336+tubes&_sacat=0&_sop=16
6528: https://www.ebay.com/sch/i.html?_fr...itleDesc=0&_odkw=6528+tubes&_osacat=0&_sop=16

Specifications Sheets:  show their heater current requirement s 5A, too much for the 4A capability of the TA-26
6336A: https://frank.pocnet.net/sheets/127/6/6336A.pdf
6336B: https://frank.pocnet.net/sheets/077/6/6336B.pdf
6528: https://frank.pocnet.net/sheets/127/6/6528.pdf
6528A: https://frank.pocnet.net/sheets/077/6/6528A.pdf


----------



## hmscott (Mar 12, 2022)

As an additional question to Xduoo, about the 6BL7/6BX7:

hmscott <hmscott@gmail.com> Dec 31, 2021, 2:57 PM to service@xduoo.com
"Hi, I didn't want to get too many things into that one email, so here is the 2nd part of what he asked, can the TA-26 support the 6BL7/6BX7, I am assuming pertinant to my question about the 6as7ga:
"Scott,Yes,I have,NOS or used?The best tubes that fits your 8BD socket if you have enough filament current is 6528 and you may try 6BL7/6BX7,THX"
What do you think?
Thank you!, Scott"

Here is Xduo's response:

service@xduoo.com Feb 28, 2022, 2:46 AM (12 days ago) to me
"Hi, Scott
Looking at the datasheet, it can be used, but we haven't tried it, and we can't buy this tube in China
Best Regards,"

_*Trying the 6BL7 / 6BX7 in the TA-26 would be experimental *_

6BL7 Information: https://tdsl.duncanamps.com/show.php?des=6BL7
6BX7 Information: https://tdsl.duncanamps.com/show.php?des=6BX7


----------



## hmscott

Hi Guys/Gals, found these interesting articles on tubes, not quite specific enough for any particular thread, but I thought as tube people you'd enough them 

How worried are you tube amp owners?
"Tube amp owners, with this tube "crisis" how worried are you?"

As a IEEE article about tubes,  I found it very informative:

THE COOL SOUND OF TUBES
One of the last remaining tube domains is in music applications, but there the devices flourish and even innovate


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## hmscott (Mar 20, 2022)

I hadn't heard, but just found out that Hifigo is dealing with Shenzhen's shutdown for Covid:
https://hifigo.com/pages/hifigo-shipping-delay-during-shenzhen-covid-19-lockdown
HiFiGo Shipping Delay During Shenzhen Covid-19 Lockdown​We are sorry to tell you that Shenzhen, our city, had locked down due to Covid-19 guidelines from Goverment untill March,20th.  
Shipments have been and will be delayed. We are still able to ship out our orders while adhering to the guidelines, but the processing and shipping time would be longer than usual. Some orders may have already been shipped out but may take a while for the courier companies to update the tracking links.
Please be assured that our whole team is doing our best to handle the orders as quickly as possible. We will continue to keep you updated, should there any major changes again. We sincerely seek your understanding in this matter and our customer service team will be 24/7 for you still online. Thank you very much.
Cheers,
HiFiGo Team

Hopefully the lockdown ends when planned...

Update: Hifigo posted an additional update at that URL and via their front page header:

_*Updated 3/20/22*_
*We are happy to tell you that HiFiGo shipment will be resumed since 3/21/22, we really appreciate your highly support and understanding during this week. Your order will be handled asap when we are back tomorrow. *


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## roderickvd

I think I'm bit by this too. This weekend I placed an order with Shenzhen Audio through Amazon. On Monday the shipping label was printed and registered with DHL, but so far the package hasn't been received by DHL yet. I've seen the same happen with some AliExpress orders from around the same time.


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## hmscott (Mar 17, 2022)

roderickvd said:


> I think I'm bit by this too. This weekend I placed an order with Shenzhen Audio through Amazon. On Monday the shipping label was printed and registered with DHL, but so far the package hasn't been received by DHL yet. I've seen the same happen with some AliExpress orders from around the same time.


You could email them and ask 
support@shenzhenaudio.com

I hadn't known of the lockdown, and I didn't check the Hifigo.com site before I sent an email asking for a custom cable to go with an IEM order, and this is the reply I received back:

"Hello Scott,
Owing to the covid-19, Shenzhen is in a lockdown and would last one week. And the workers in the factory don't work. So we would handle this thing next week.
Hope you could understand.
Best Regards, xx"

I wrote back:

"Thank you xx!  Of course, I hope you all stay safe and healthy! 
Good health and happiness to all of you 
Scott"

"Hello Scott,
Thank you~
You too "

I'm sure the nice folk at Shenzhen Audio would also be happy to assist your inquiry about the state of shipping your item(s).

Long back, when Covid first hit, and China was having country wide shutdowns, I had an order that was waylaid for weeks, but as soon as they could go back to work (Hifigo.com) they shipped it right out.  We exchanged many emails during that lockdown time, getting to know each other, discussing various subjects, and I think it helped both of us get through it all.


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## roderickvd

I can be patient. Other than to satisfy my curiosity I am sure that they will ship as soon as they can. DHL will alert me once they have. Hopefully the good folks in Shenzhen will be safe and healthy.


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## Ufanco

I been doing some tube rolling on the Xduoo t20 so thought I add my thoughts on tubes I tried. My setup is shanling m6 pro 21 as source into a Oriolus BA300S mkii as preamp then the Xduoo Ta20. Using the Mest mkii iem’s I wanted the amp and preamp to not add any hiss to the sound. This setup allowed me to reach this goal.
Tubes tried so far and ranking of each.
AMPEREX 12AU7/ECC82 so far the best sounding that I tried.
NORTHERN  ELECTRIC 12au7 came with the used Xduoo surprised on sound since it’s a new tube.
RCA Cleartop 12au7 close to the northern electric feel each has it plus and minus.
WESTINGHOUSE CONN Long black plate D getter 12au7 nothing special sound wise.
stock tube well the music played that about all. Shame they included these tubes highly recommend replacing, even the inexpensive RCA cleartop is a big improvement over these tubes.

It’s a bit overwhelming since there so much choice on the 12au7 tube options. still i’m having a blast trying different tube since there’s definitely a difference in sound quality. Much more noticeable than a cable or even a tip change. 





​


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## roderickvd

Shenzhen shipped this morning. Quarantine must have been lifted according to plan! Should arrive first week of April.


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## Ufanco

roderickvd said:


> Shenzhen shipped this morning. Quarantine must have been lifted according to plan! Should arrive first week of April.


Awesome I would suggest looking for something to replace stock tubes well you wait. Even something like a rca cleartop sounds  much better than stock. Can get some great deals on the ones marked conn. There made for organs and inexpensive.


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## roderickvd

I already have a matched pair of Sylvania 6189’s waiting to be installed!


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## albertmuc

„xDuoo TA20“: I currently use the XLR (balanced) input and the single-ended 6.5mm output for my headphones. 
Would there be a sonic gain on the XLR (balanced) output…?


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## roderickvd

For sure. The single-ended output goes through an opamp, the balanced one doesn’t.


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## hmscott (Mar 22, 2022)

albertmuc said:


> „xDuoo TA20“: I currently use the XLR (balanced) input and the single-ended 6.5mm output for my headphones.
> Would there be a sonic gain on the XLR (balanced) output…?





roderickvd said:


> For sure. The single-ended output goes through an opamp, the balanced one doesn’t.


Well, we know that the 2 RCA single-ended inputs are converted to balanced signals internally via opamp's. The now balanced signal is pre-amplified by the tube stage, and then further amplified by the discrete Class-A transistor stage to drive the headphone outputs.

An opamp isn't needed, or possible, to convert the amplified balanced signal, it is split off to the XLR and SE outputs via the discrete output stage.

Both the XLR and SE outputs are supposed to be the same wattage output.

Here is what the Xduoo product page says for power output via the XLR and SE outputs:
Output power: Phone: 2,000 mW (32 ohms); XLR: 2,000 mW (32 ohms)

I do recommend using the Balanced output if only to hear the difference between the balanced output and the single-ended output, and on many amps/DAPs there is a power advantage given to their balanced output so for listening on headphone amps other than the TA-20 it is important to be equipped to connect with an XLR / 4.4mm / 2.5mm / 3.5mm balanced cable to connect to a balanced output to reap the power and potential tonal advantages.

On the TA-26 I do notice a tightening of the center image with the SE output as compared to the TA-20 SE and XLR balanced output - at least it is noticeable to me


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## albertmuc

hmscott said:


> Well, we know that the 2 RCA single-ended inputs are converted to balanced signals internally via opamp's. The now balanced signal is pre-amplified by the tube stage, and then further amplified by the discrete Class-A transistor stage to drive the headphone outputs.
> 
> An opamp isn't needed, or possible, to convert the amplified balanced signal, it is split off to the XLR and SE outputs via the discrete output stage.
> 
> ...


@hmscott: Thank you for your experiences!


With "xDuoo TA-20" the use of balanced input is important, so I use it. 

The tonal difference between the balanced output and the single-ended output seems to be not striking. If there are any further listening experiences regarding the tonal differences between the two outputs on the TA-20...

Would like to use the balanced output, as far as "really" advantageous, unfortunately I would have to buy a balanced cable first, hence my question…


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## YanaMJ

albertmuc said:


> „xDuoo TA20“: I currently use the XLR (balanced) input and the single-ended 6.5mm output for my headphones.
> Would there be a sonic gain on the XLR (balanced) output…?


I've tried to use XLR input with single-ended output but sound is very very low (need to put on 95 level)

When I use the RCA input with XLR output or SE output it works fine and sound power is the same on both outputs (max 65)

XLR input with XLR output same volume than for the RCA input on both SE or XLR


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## roderickvd (Mar 22, 2022)

I might have been wrong about an opamp in the output stage. Indeed it is discrete, but it still needs a buffer which will have sonic characteristics. What I don’t know is, maybe the balanced output is buffered too so hard to say if there would be a difference then.

A different point is that balanced outputs double the output impedance, which is actually detrimental. If the output impedance is low enough, as it should be with a hybrid, it won’t really matter, but technically this is a downside to balanced listening. I emphasize technically, and just putting this out here for sake of completeness.


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## CJG888

Has anyone tried the MU-601 DAC? I suspect it might make quite an effective mini-stack Schiit alternative together with the MT-602.


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## muchacho (Mar 23, 2022)

Hi, I'm a newbie here and I'm also new to the "space" of tube headphone amplifiers. I have Sennheiser HD600 headphones and I first bought RME ADI2 DAC FS. Then I wanted to "taste" the sound of the lamps and bought a hybrid xDuoo TA-10R, and finally two months ago I became the happy owner of the TA-26. This amplifier is unique in connection with the HD600 and my ears are "in the sky". But I would like to upgrade the default tubes, so I found 6SN7GTB TUNG-SOL and 6AS7GA GENERAL ELECTRIC tubes in our e-shop in CZ, all new production and at a good price. Does anyone have experience with this combination in the TA-26 amplifier?


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## dpump

English language only on head-fi per the rules.


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## muchacho

I'm sorry, a little confusion with the translator ...


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## hmscott (Mar 24, 2022)

muchacho said:


> Hi, I'm a newbie here and I'm also new to the "space" of tube headphone amplifiers. I have Sennheiser HD600 headphones and I first bought RME ADI2 DAC FS. Then I wanted to "taste" the sound of the lamps and bought a hybrid xDuoo TA-10R, and finally two months ago I became the happy owner of the TA-26. This amplifier is unique in connection with the HD600 and my ears are "in the sky". But I would like to upgrade the default tubes, so I found 6SN7GTB TUNG-SOL and 6AS7GA GENERAL ELECTRIC tubes in our e-shop in CZ, all new production and at a good price. Does anyone have experience with this combination in the TA-26 amplifier?


Hi!, and Welcome to head-fi.org 

My first Power tube was also a G.E. 6AS7GA, and one of my first Pre-amp tubes were a few VT-231's and a 6SN7GTA SYLVANIA TALL GLASS tube - and I found the best combination of tubes from that 1st batch of tubes for the TA-26, to my ears, was the GE+6SN7GTA... but, all the tubes were measuring "New" and so hadn't been "burned-in" - where the cathode burns off the oxides and coatings that rest on it during manufacturing process. Usually it is recommended to burn-in the tubes for 50-200 hours before critically listening.
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16755621

Now after running these tubes and more for a few months, I find that the 1944 VT-231 KenRad Black Beauty sounds best in the Pre-Amplifier position - from that same 1st batch of tubes - and for the Power tube position I have a few favorites - it depends on how much solid Bass and "solid-state" sound you want.  Some interesting GE => Kenrad history that is good to be aware of when tube hunting:
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-16865356

For me the 1976 Cetron 7236 provides a closer to "solid-state" focus and impact, while allowing the Pre-Amplifier tube to push through with the tubiness air and sound stage.  While I do enjoy that, it is also nice to change up that sound by swapping in a Svetlana '85 6N13S or a RCA '61 6AS7G or a 1950 Jan RCA 6AS7G power tube.

I also enjoy the 1957 JAN CBS-Hytron 5692 in the pre-amplifier position, as compared to the 1940's VT-231's it carries more weight and slam, but also has the wide sound stage and airy presentation.

Another great pair of tubes are the Russian Melz 6N8S tubes, a '53 Melz 6N8S and a '54 Melz 6N8S, these have an extended treble range which I do enjoy too. Matched with the 7326 the sound is the most detailed and SS sounding, while still retaining that tubey sound stage and airyness. Subbing in a Russian 6N13S brings back more of the warmth while maintaining the high end extension from the Melz preamplifier tubes.

There is no one tube or combination that I could recommend to satisfy everyone, but I would recommend finding new measuring tubes with 100%+/100%+ of "lifetime" remaining, or 100% of New parameters specific to the tester that the seller lists as the tool used to measure and publish results for that tube.

I found that it helped for me to acclimate to the new sound of the TA-26, listening to the differences I heard in my Dynamic / Planar headphones and my various IEM's for a couple of weeks before ordering more tubes.

Right now I am listening on the TA-26 with a 1961 Svetlana 6N13S and the 1944 VT-231 KenRad Black Beauty...

And, for now, I think I am ok with what I have...at least for a little while...


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## kibot (Mar 24, 2022)

Privet guys!✌
So i bought _*Sennheiser HD 600 *_as   *hmscott *recomended and what can i say - this is one of the best choise for *TA26 *on its budget
Sounds pretty awesome !!!👌😁🤟
P/S Great thanks *hmscott *!!!


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## hmscott (Mar 24, 2022)

That is awesome @kibot, I'm thrilled to hear you love your new HD600 on the TA-26 

They can get better over time, at least my HD660s and HD598cs did, so you have even more fun sound to discover over time.

Thank you for sharing your experiences on the TA-26


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## kibot (Mar 24, 2022)

Hehe thank you too,
hmscott for advice!👌😎
Thats absolutely awesome now 🎶❤🤟🤟


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## hmscott (Mar 24, 2022)

Hi, I happened to see a new Asahi Kasei Microdevices (AKM) DAC video released on AKM and on Youtube minutes ago, along with technical specifications:

AK4493S / AK4490R Advanced VELVET SOUND Technology Developer's Interview
https://www.head-fi.org/threads/ak4...ogy-developers-interview.962696/post-16880085

AK4493SEQ  NEW  123dB 768kHz / 32-bit 2 channel Premium DAC
https://www.akm.com/us/en/products/audio/audio-dac/ak4493seq/

AK4490REQ  NEW  120dB 768kHz / 32-bit 2 channel Premium DAC
https://www.akm.com/us/en/products/audio/audio-dac/ak4490req/

Has anyone seen any new development using the new AKM DAC chips?


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## muchacho (Mar 25, 2022)

hmscott said:


> Ahoj!, a vítejte na head-fi.org
> 
> Moje první power lampa byla také GE 6AS7GA a jedna z mých prvních lamp pro předzesilovač bylo několik VT-231 a 6SN7GTA SYLVANIA TALL GLASS lampa - a našel jsem nejlepší kombinaci lamp z té 1. várky lamp pro TA. -26, podle mých uší, byla GE+6SN7GTA... ale všechny elektronky měřily "Nové", a tak nebyly "zapálené" - kde katoda spálila oxidy a povlaky, které na ní spočívají. během výrobního procesu. Obvykle se doporučuje před kritickým poslechem elektronky zapálit 50-200 hodin.
> https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16755621
> ...



Thank you for the answer, tips and links to the vacuum tubes for TA-26!  I see that with the vacuum tubes I have embarked on a long and instructive journey, full of interesting musical and sound experiences. Now I am waiting for the shipment of the mentioned GE and TUNG SOL tubes and in addition I found and ordered the Philips ECG 6080WC tube in the dealer's offer, so maybe I didn't make a mistake with it and it will work in the TA-26? Otherwise, I only found out during a phone call with the seller that GE and Philips are from the NOS category and they were both for an interesting price (in terms of GE for 9.5 USD and Philips for 17USD). But as I wrote above, as a beginner I still have to learn ...


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## Oscar-HiFi

Just fyi a socket saver is perfect for using 6080 valves in the TA-26 - brings them up to the right height


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## muchacho

Thanks for the next tip! I already thought about it, the rear tube will be drowned. Where can I get such a saver? Or under what "word" should I look for him?


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## hmscott (Mar 27, 2022)

muchacho said:


> Thank you for the answer, tips and links to the vacuum tubes for TA-26!  I see that with the vacuum tubes I have embarked on a long and instructive journey, full of interesting musical and sound experiences. Now I am waiting for the shipment of the mentioned GE and TUNG SOL tubes and in addition I found and ordered the Philips ECG 6080WC tube in the dealer's offer, so maybe I didn't make a mistake with it and it will work in the TA-26? Otherwise, I only found out during a phone call with the seller that GE and Philips are from the NOS category and they were both for an interesting price (in terms of GE for 9.5 USD and Philips for 17USD). But as I wrote above, as a beginner I still have to learn ...


Hey that's great, and yes it is a voyage of discovery 

Here are some head-fi.org threads to read up on, especially the 1st post in each link, which cover the variations of the 6AS7G and 6SN7 series:

For 6AS7G tube rollers here .....
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

The Reference 6SN7 Thread
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/

Here is some GE / Kenrad History:
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-16865356

It is an interesting way to learn history 


Oscar-HiFi said:


> Just fyi a socket saver is perfect for using 6080 valves in the TA-26 - brings them up to the right height





muchacho said:


> Thanks for the next tip! I already thought about it, the rear tube will be drowned. Where can I get such a saver? Or under what "word" should I look for him?


I suppose it is a matter of personal taste, but I tried socket savers and found they were more trouble than help, at least on the TA-20.

I bought the socket savers to avoid "wearing out" the sockets of the TA-20, but due to the recessed sockets on the TA-20 the socket savers were difficult to "hold down" while pulling out tubes from them - and in the end the socket saver/tube came out together and the TA-20 socket was still being "used".

After many insertions and removals the TA-20 socket is still just as tight and solid.  I use slow care when pulling up and slightly rocking the tube from side to side to "edge it out" of the socket, and that has seemed to be a good gentle approach to remove the tubes.  Inserting is simply aligning and gently applying pressure until the the tube inserts.  I'm no longer worried about the socket wearing out.

As far as a lower height power tube being behind the front preamp tube, I don't really notice the difference after the first novelty of it wore off.

I've used "step-sided" tubes like the 6AS7G and 6H13C which that position was designed to accommodate, as well as the shorter straight-sided 6AS7G and 7236's, and while the size is different the installation and removal technique are the same.

There are also small 6080 and 5998 straight-sided envelope tubes as well as the 5998 "step-sided" envelope tubes, and they are all easy to insert "blind" with the "key" alignment.  It does feel odd the first time trying to find the "keyhole" with such a wide access hole for the socket with a smaller tube, but after the first couple of times it becomes "normal".

I'm installing and removing tubes often enough I found the socket saver was another item that got in the way after a short while.  It quickly seemed much easier to insert/remove directly into the amp socket, giving extra care assuaged my anxiety over wearing out the amp tube socket.

I also found ceramic socket replacements with gold-plated lugs, and looked up how to disassemble the TA-20 so that I was prepared should the TA-20 socket "give way" after so many insertions/removals.  After a couple of years of use I've still not bothered to purchase replacement ceramic sockets for the TA-20 because I'm no longer worried about wearing them out.  YMMV.


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## albertmuc (Mar 26, 2022)

Because of the now burned-in tubes (see photo), I once again express my enthusiasm for the inexpensive "xDuoo TA-20". Balanced connected to the decent-sounding "RME ADI-2 Dac", I prefer the "xDuoo TA-20" with its tube magic, which takes the edges out of the sound, makes voices livelier and everything more three-dimensional. 
Actually, I wanted to invest in a “somehow better” tube amplifier, but it already sounds very good… 
Don't be put off by the low price of the xDuoo!


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## hmscott (Mar 26, 2022)

albertmuc said:


> Because of the now burned-in tubes (see photo), I once again express my enthusiasm for the inexpensive "xDuoo TA-20". Balanced connected to the decent-sounding "RME ADI-2 Dac", I prefer the "xDuoo TA-20" with its tube magic, which takes the edges out of the sound, makes voices livelier and everything more three-dimensional.
> Actually, I wanted to invest in a “somehow better” tube amplifier, but it already sounds very good…
> Don't be put off by the low price of the xDuoo!


I think Xduoo was trying to help me find my tube Nirvana when they gave me the TA-26, it really is a big jump in Tubiness! 

I was about to stop collecting tubes for the TA-20, but when I listened to the TA-26 with stock tubes; I'm all in again big time!  And, the TA-26 is even less expensive than the TA-20!


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## ostewart

muchacho said:


> Thanks for the next tip! I already thought about it, the rear tube will be drowned. Where can I get such a saver? Or under what "word" should I look for him?



https://www.ebay.co.uk/itm/281952845500

@hmscott personally I wasn't looking to "save" the tube socket as such, it was more of a height thing to bring the 6080 tube a litle higher so aesthetically it looks better - it could also help with thermals as the hot element is higher and not as close to the capacitors (fully outside of the amp now)


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## muchacho

ostewart said:


> https://www.ebay.co.uk/itm/281952845500
> 
> @hmscott personally I wasn't looking to "save" the tube socket as such, it was more of a height thing to bring the 6080 tube a litle higher so aesthetically it looks better - it could also help with thermals as the hot element is higher and not as close to the capacitors (fully outside of the amp now)


Thanks for the tip, this is exactly what I meant so that the 6080WC and 6SN7GA would not be drowned due to the heating inside the amplifier and that they would also be visible. I like to enjoy listening in the evening, when the pleasant warm glow of the tubes stands out and combines with the same pleasant sound ... In the end, I found and ordered this base pad:   https://www.fruugo.cz/osmickova-pozlacena-trubkova-zakladna-pro-usporu-z-trubky/p-61951742-124933236


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## roderickvd (Mar 28, 2022)

I received my TA-20 today and am listening to it as we speak. I am sorry to say that my initial impression is very disappointing. The sound is unpleasantly distorted, grainy, and the soundstage compressed. For reference, my previous amp I am comparing this to is a home-built AMB β22.

This is listening to my 250Ω Beyerdynamic Amiron Homes (XLR) and my home-built Soekris dam1121 (RCA) as source. Swapping the balanced headphone cable with an unbalanced cable did not make any discernible difference.

I changed the stock tubes to a NOS matched pair Sylvania 6189W's, also to no avail.

I should receive my Denafrips Ares II this week, which will provide XLR input to the TA-20. That together with some further burn-in will hopefully fix whatever I'm hearing, or I'll be selling this unit. Hopefully I won't need to?

Edit: man, I do hope it's those OPA's that are doing the RCA unbalanced to balanced conversion internally. Fingers crossed.


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## hmscott (Mar 30, 2022)

It is easy to give up quickly, I've seen others do that as well.  I hope you stick with it and work out what tubes sound good in the TA-20. 

Early on I found and posted this review comparing the Sylvania 6189 and the PSVANE 12AU7-TII:
https://www.audiosciencereview.com/...mp-money-can-buy-for-hd800s.18522/post-606270

"5.0 out of 5 stars - A surprisingly huge step up from Sylvania and other NOS tubes
Reviewed in the United States on May 19, 2020
Verified Purchase
Came in a beautiful presentation box with papers showing serial #s and measurements. Used them to roll from Sylvania NOS. 6189/12AU7. I was amazed at how much stronger these PS VANES were over the Sylvania NOS.
Truly impressive!
Update: I also have some RCA NOS, Mullard re-issues, and a few other matched NOS tubes of varying brands.
These PS VANE T2 tubes clearly outperformed them all in my XDUOO TA20 hybrid headphone amp.
I liked them so much that I ordered a 2nd pair, along with matching PS VANE T2 power tubes of another designation, to go into a Cayin HA1A MK2 headphone amp I recently ordered elsewhere.
The difference between this PS VANE T2 and others is immediately a huge noticeable improvement. The others I could tell differences, some more subtle than others. If you blind folded me and asked me to identify 1 of the other brands over the others, i might guess correctly half the time. Then there's these. They're unmistakable.
Its like going from a home theater in a box with a 50" 720 p monitor with Dolby Digital 5.1 (not bad) to a 140 inch UHD projector and a 7.2.4 Dolby Atmos system( WOW). There's no going back.
They probably would be wasted on a guitar amp where distortion might be preferable, but for hi fidelity music reproduction, these are really hard to beat."

And, while at the time I really enjoyed the PSVANE 12AU7-T II tubes in comparison to the "new reissue" 12AU7's I tried in the first weeks, I wouldn't say it was "up there" enough to recommend today.  Which would put the Sylvania 6189W well down the list under the PSVANE 12AU7's as well.  So I wouldn't feel bad if it doesn't sound good to you either.

We moved the TA-20 tube rolling discussions to the TA-20 review thread within a few posts in that thread above:
https://www.audiosciencereview.com/...-headphone-amplifier-review.10118/post-611207

I also made a bunch of posts on my early experience with TA-20 in that thread.  If you want to speed through to the best tubes, I'd not buy those early trial 12AU7 tubes.  At least wait until you find where I switched over to 12AT7 there and here, then found the E80CC and E180CC tubes, both Mullard NOS made in the Mullard Mitchum plant in Surrey England and the top sounding for me so far, the Amperex E180CC made in Heerlen, Netherlands.

Hopefully you can find local vintage tube sellers that can get you those same Amperex / Philips or rebranded tubes made in the Heerlen plant - it is right there in your "back yard"

There are a lot of tubes that sounded "flat" to me as well, but I didn't give up, I kept upping the "ante" buying more expensive tubes - but looking for the best price historically before blowing too much.  I tried to keep it to $50/tube as for the ECC81/4024/8162 Mullard ala Mitcham Surrey England plant, but went as high as $80/tube for the "Pinched Waist" Heerlen E180CC pair.

You also need to burn-in the tubes for 50-100 hours before making "sound judgements" on what the tubes can do.  New tubes - as in never used - need to burn off the cathode material for a while before the tube will "mellow" out and fly right.  The TA-20 and the stock tubes need burn-in too, some have reported enjoying those stock tubes after 40-50 hours - I never burned them in myself, I started rolling new tubes first thing.

And, we really cannot A/B test tubes except side by side in the same set up's, as swapping tubes means cooling down and heating back up for hours before the best sound comes through.

So patience is the watch word, and let things age in first before making sound judgments


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## roderickvd (Mar 29, 2022)

Thanks for your extensive reply. As always, it seems!

Have you been running the amp from a balanced or unbalanced input? I really think — hope — that it’s that. Also because rolling the stock tubes made no discernible difference, I think it’s elsewhere in the chain.

I am fully aware that it takes a good number of hours of burn-in for tubes and caps to come to life. I did however have much higher expectations even on initial listening, based off of many reviews with positive first findings. On forums like this one as well as Zeos’ super positive review. My initial impressions are far from that.

As for the Sylvania’s, I will not argue that the Heerlen tubes are a another step up surely. Still, there are *many* who think the Sylvania’s make the top of the list just beneath that, having posted reviews counter to the one you quoted. Personal preference of course but I’m holding on to the thought that these are some good tubes which should not produce such unpleasant distortion by a far stretch.

Again, Zeos loved the TA-20 on first listen even with stock tubes.

I’ll continue listening on this unit and wait for my Ares to arrive, and postpone final judgement until I’ve hooked that up balanced.


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## -Darkstar-

roderickvd said:


> I received my TA-20 today and am listening to it as we speak. I am sorry to say that my initial impression is very disappointing. The sound is unpleasantly distorted, grainy, and the soundstage compressed. For reference, my previous amp I am comparing this to is a home-built AMB β22.
> 
> This is listening to my 250Ω Beyerdynamic Amiron Homes (XLR) and my home-built Soekris dam1121 (RCA) as source. Swapping the balanced headphone cable with an unbalanced cable did not make any discernible difference.
> 
> ...


Even though it's a hybrid and not a full tube amp, I'd give it around 100 hours before making a final decision. My TA-30 sounded very closed in at first, also.


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## hmscott (Mar 30, 2022)

roderickvd said:


> Thanks for your extensive reply. As always, it seems!
> ...


I find if I answer in short without supporting info, worse conclusions can be jumped to due to inadequate information - and their inability to read my mind. 

So I prefer to go into detail in my responses vs trying to repair a misunderstanding in many following posts.  So far that works well, unless the person isn't interested or doesn't read well.  And then in the long term my longer responses are helpful to others that come across them later.

I'm answering to help, and if I don't cover things well at first edit, I often come back and edit my post(s) to fill in words, details, and add links to firm up the specifics.  And, I come back sometimes with "Updates".


roderickvd said:


> Have you been running the amp from a balanced or unbalanced input? I really think — hope — that it’s that. Also because rolling the stock tubes made no discernible difference, I think it’s elsewhere in the chain.


I've run the TA-20 in both XLR and RCA, and I prefer XLR on the TA-20 but on the Topping A90 I prefer RCA...it isn't a big difference for either, it is a preference based on longer term listening, and I had to pick one or the other in order to drive both at the same time from my Topping D90 MQA DAC.

Right now I am driving the TA-20 via XLR from the Topping D90 XLR output, and the TA-26 via the RCA output of the Topping D90 - the D90 can be set to output to either RCA or XLR or both at the same time.

Again the difference between the XLR and RCA input of the TA-20 for me is much less than between good and great tubes, and between a broken in TA-20/tubes - and the sharp edged harshness of new unused tubes - *harshness which can be extreme with some new tubes!*


roderickvd said:


> I am fully aware that it takes a good number of hours of burn-in for tubes and caps to come to life. I did however have much higher expectations even on initial listening, based off of many reviews with positive first findings. On forums like this one as well as Zeos’ super positive review. My initial impressions are far from that.


Well, not so much to come to life as to remove the rough edges of harshness from the new tubes/equipment.  There are other dimensions to the changes, *but you are reporting - in my estimation - the harshness of distorted edges from the new tubes and/or new TA-20, both not yet broken in.*

I've experienced it many times with new tubes on the TA-20 and now on the TA-26.  The tubes do at first have good qualities and bad qualities.  Some/most tubes shed the bad sharp/harshness qualities over time and as I and many call it - mellow out.  And, the sound stage can widen and the overall frequency balance can improve.  Each tube is different in the changes over burn-in, but so far none have become worse sounding.

I also experience this burn-in harshness with IEMs/headphones - as with the Sendyaudio Aiva Zeos uses in the TA-20 review where he says you really need a Hybrid amp for Planars - which I have found isn't always the case - the TA-26 drives my Hifiman HE6SE V2 quite well - even though it is very inefficient and has low impedance.

I've A/B'd both the Hifiman HE6SE V2 and Hifiman Ananda between the TA-20 and TA-26, and with certain tubes in the TA-26 - specifically the 1976 Cetron 7236 power tube and the 1944 Kenrad VT-231 Black Beauty (Black Glass) the TA-26 sounds just as great as the TA-20 with Haltron E80CC (Heerlen made) or E180CC Heerlen made tubes.


roderickvd said:


> As for the Sylvania’s, I will not argue that the Heerlen tubes are a another step up surely. Still, there are *many* who think the Sylvania’s make the top of the list just beneath that, having posted reviews counter to the one you quoted. Personal preference of course but I’m holding on to the thought that these are some good tubes which should not produce such unpleasant distortion by a far stretch.


In my experience my first tubes - as carefully researched and selected as I could make them - didn't hold up over time, and like the Sylvania 6189W your early tubes may similarly be near the bottom of your list, after you run through a lot more tubes, hunting for better and better tubes.

tubemazestore - a longtime tube seller on eBay that also has a tube review site with 5000+ reviews submitted as of August 7, 2020 - see top rated 12AU7 list below.

The Sylvania 6189W Triple Mica received 3.84 out of 5 - (32 votes, average: 3.84 out of 5) Is your 6189W a 3 Mica build?, one on the bottom of the stack and 2 with a short gap on top?  Most 12AU7's (and other 12xx7's variants) are built with 2 Mica, one top and one bottom, but the best sounding are typically the 3 Mica variant also usually built with stronger posts and tie points to keep the tube rigid in the glass envelope - those more solid builds reduce the noise and microphonics.
https://tubemaze.info/sylvania-618912au7wa-gray-plates-triple-mica/

Here are the tubemaze.info site's top rated 12AU7 tubes as of August 7th, 2020:
https://tubemaze.info/the-best-12au7-tubes/

"Which 12au7/5814 tube won the right to be called the best and the worst?

Updated August 7th, 2020

Based on user ratings in the last 8 years and over 5000 ratings submitted, here is the list of winners and losers. The system is based on 5 stars. We will treat 5814, 7316 and 12au7 in the same category – since they are the same tubes, just different quality.

Old Stock 12au7
Winners

Amperex 7316 Long Plates Foil Getter (4.8)
Mullard 12au7 Long Plates []-getter (4.6)
Mazda 12au7 Gray Plates (4.57)
Mullard 12au7 10M Series (4.5)
Tung-sol 12au7 Black Glass (4.43)
No surprises here, all of them are crazy good tubes. Amperex 7316 with long plates still reigns supreme.

*The 3-Mica Sylvania 6189 with 3.84 rating didn't make the top 5, and probably not the top 10...note below the PSVANE 12AU7-T Mk.1 received an average of 3.18!, the site search doesn't find the PSVANE 12AU7-T Mk II - too new?, but it did find the **PSVANE 12AX7-T MK II **which received a 3.38.  So perhaps I would enjoy the Sylvania 3.85 more than the PSVANE 12AU7-T Mk II, but in any case I have a far more enjoyable 12AU7 in the Tung-Sol 12AU7 Black Glass 4.43 rating - which are my current best sounding 12AU7 tubes - I recommend to always get backup's of your favorite tubes - if possible *

Losers

Sylvania 12au7 Short Black Plates (3.0)
Sylvania 12au7 Gray Plates (3.0)
Mullard M8136/12au7 Box plates England (3.28)
Now that is a surprise, based on 39 reviews submitted, Mullard M8136 took the third place from the bottom! The very unexpected outcome for this tube. Interestingly enough, Mullard CV4003/12au7 Box Plates earned a very respectable rating of 4.4

New Production 12au7
Winners

*Well, there are really no winners in this category for new production tubes, all of them rated very poorly.  - That is my experience as well, while "nice" they really don't do the TA-20 justice.

Losers

ShuGuang/Ruby 12au7 Gray Plates (2.0) - AFAIK these are the stock tubes provided with the TA-20.
Psvane 12au7-T (3.18)* *- These are the predecessors to my PSVANE 12AU7-T Mk II's and PSVANE 12AU7-S Mk I's.*
Electro-Harmonix 12au7 (3.22)
*And again ShuGuang 12au7 takes the lead on being the worst of the worst – 2.0 is quite an achievement – again, too bad that a lot of manufacturers choose to ship their equipment with this tube. - IDK why Xduoo keeps using these as the stock tubes when the much better Chinese PSVANE tubes are available now...some Chinese amp makers offer a PSVANE tube upgrade option - perhaps Xduoo could add that as an option for the TA-20 / TA-26 / ?? models?

DISCLAIMER: This is not a definitive list of all best and worst 12au7. It’s purely based on over 5,000 ratings submitted by the users of this site."*
_*My comments added to the article quoted above are in Italic Bold....*_


roderickvd said:


> Again, Zeos loved the TA-20 on first listen even with stock tubes.
> I’ll continue listening on this unit and wait for my Ares to arrive, and postpone final judgement until I’ve hooked that up balanced.


Zeos was comparing the difference between the TA-10 single-ended sound vs the TA-20 Balanced sound, and as far as the stock tubes Zeos says "I think if you swapped tubes you could have an "end game" "- and Zeos's comment wasn't that stock tubes sounded better, but that Balanced sounded better - more specifically the TA-20 sounded better with stock tubes than the TA-10 with burned-in swapped tubes.

But I don't think Zeos did a good job qualifying that comparison if you got out of it that the stock tubes were great sounding, or that they were responsible for what Zeos was praising - it wasn't the sound of the stock tubes it was the difference in sound presentation between the "single-ended" TA-10 and the "balanced" design of the TA-20.

As above the TA-20 stock tubes got a 2.0 rating and I agree that they are very harsh sounding on their own, and not at all enjoyable, that is why I didn't listen more than a short while (minutes) to them before rolling in tubes that sounded much better than the stock TA-20 tubes.

Zeos's comments as above start here:  Xduoo TA-20 _(Z Reviews)_ Truly Balanced

The TA-20 Balanced sound sounds much different than the "Pulled to the Center" single-ended TA-26 sound...at least initially.  Now that I've listened to the TA-26 for a few months that "sucked to the center sound" I had with the stock tubes and unburned in TA-26 is completely gone.

If you continue rolling tubes, and continue using the TA-20 all day long - keep it playing music even if you aren't listening to it to get it through full burn-in, you will find a much more musical and melodious sound from your TA-20 too 


-Darkstar- said:


> Even though it's a hybrid and not a full tube amp, I'd give it around 100 hours before making a final decision. My TA-30 sounded very closed in at first, also.


Totally agree, and for me the TA-20 sound kept improving all during the first couple of months of use, and that was about the time I found the Tung-Sol 12AU7 Black Glass tubes and stopped listening to the Topping A90 completely - except for specific comparisons to answer questions posed to me online.  Now, the A90 is sitting unplugged under the TA-20...

I would expect the TA-30 to need as much burn-in time too.

For me the stock TA-26 was stuck on stock tubes for a couple of weeks until I could get new tubes plugged in, and I often went back to my TA-20 simply because I thought the TA-26 stock tubes as still new sounded too harsh - but, with the TA-26 wide sound stage and "airy tubiness" being much better than most TA-20 tubes sound, even while the harshness played out during burn-in.

@roderickvd - *I also should mention that for both the TA-20 and TA-26 with new tubes I find it helps to reduce the XLR 4.0V drive output from the D90 DAC as it reduces the "edgy-ness" or harshness at listening volume with new tubes.  With new tubes not yet burned in, on the Topping D90 I reduce the XLR 4.0V output by setting a -15dB or -20dB attenuation - with the PC source audio still set at 100% output to maintain analog Signal-to-Noise audio integrity, and that helps to reduce the harshness during burn-in.  After the amp/tubes burn in I run the D90 DAC at 0.0dB output attenuation - like right now.

The DAC output attenuation, even as little as -3.0dB, -6.0dB or -9.0dB might be enough to help you reduce the harshness you are hearing during new TA-20 / new tubes burn-in.  Trying playing around with the DAC attenuation starting at -3.0dB and increase attenuation until the harshness is reduced as well as possible.  Of course, increase the volume on the TA-20 as needed to return the listening level to where you like it.

Nothing beats actual hours burn-in time, but I can make the harshness more tolerable during burn-in by reducing the DAC XLR 4.0V drive input to the amp.

Additional detail for reducing DAC output: This probably only applies to XLR output @4.0V or more as with the Topping D90/D90SE.  If you are feeding the TA-20 / TA-26 via RCA 2.0V or less it won't make a difference.

Thanks to @roderickvd for his feedback, I've updated the info above to reflect his experience 

Update: **tubemazestore **was paused for a while, but it is back online again, not very much is currently listed,  I hope he brings back more of his inventory online soon *


----------



## roderickvd (Mar 29, 2022)

hmscott said:


> I find if I answer in short without supporting info, worse conclusions can be jumped to due to inadequate information - and their inability to read my mind.
> 
> So I prefer to go into detail in my responses vs trying to repair a misunderstanding in many following posts.  So far that works well, unless the person isn't interested or doesn't read well.  And then in the long term my longer responses are helpful to others that come across them later.


Well, much appreciated!


hmscott said:


> Well, not so much to come to life as to remove the rough edges of harshness from the new tubes/equipment.  There are other dimensions to the changes, *but you are reporting - in my estimation - the harshness of distorted edges from the new tubes and/or new TA-20, both not yet broken in.*


Yes, you may be on to something there. Edit: I also find it lacking in authority and presence, is that something recognisable?

It's true that I'm new to this tube game. The scientist in my has long pulled me towards the "best amp is a wire with gain" kind of thinking. It's that thinking that also led me to build my AMB β22, which may be considered reference depending on which standard you hold it to, and pulls out every technical trick in the book. But I have come to realise that this is not truly what I'm after -- at the end of the chain, I prefer that warm, lush sound of my dad's 70s setup so to speak. And here I am getting into tubes.


hmscott said:


> The Sylvania 6189W Triple Mica received 3.84 out of 5 - (32 votes, average: 3.84 out of 5) Is your 6189W a 3 Mica build?, one on the bottom of the stack and 2 with a short gap on top?  Most 12AU7's (and other 12xx7's variants) are built with 2 Mica, one top and one bottom, but the best sounding are typically the 3 Mica variant also usually built with stronger posts and tie points to keep the tube rigid in the glass envelope - those more solid builds reduce the noise and microphonics.
> https://tubemaze.info/sylvania-618912au7wa-gray-plates-triple-mica/


Yes, those are the ones. The babies were once intended for use in guided missile systems aboard highly dynamic platforms like navy ships. Unsurprising then, that they have excellent linearity, low noise and low microphonics. Again I may have fallen into the trap of technical prowess when in fact something mellower would better suit my ears... it's like a constant source of conflict between the mind and the heart 

Then there's a bit tongue in cheek too -- I work in the defense sector so imagine the coffee talk at work where I'm ever so proud to announce that guided missile technology has now found its way into my hifi equipment 


hmscott said:


> New Production 12au7
> Winners
> 
> *Well, there are really no winners in this category for new production tubes, all of them rated very poorly.  - That is my experience as well, while "nice" they really don't do the TA-20 justice.*


Here's a question that might show my newness to this tube game: aren't all PSVANE's new production? If so I do not understand why they also appear on other lists, sometimes quite well rated (and sometimes not so).


hmscott said:


> If you continue rolling tubes, and continue using the TA-20 all day long - keep it playing music even if you aren't listening to it to get it through full burn-in, you will find a much more musical and melodious sound from your TA-20 too


Doing that now. Also realising that investing in a pair of top tubes later on should be on the list -- once this unit has proven its worth to me to do so.


hmscott said:


> Zeos was comparing the difference between the TA-10 single-ended sound vs the TA-20 Balanced sound, and as far as the stock tubes Zeos says "I think if you swapped tubes you could have an "end game" "- and Zeos's comment wasn't that stock tubes sounded better, but that Balanced sounded better - more specifically the TA-20 sounded better with stock tubes than the TA-10 with burned-in swapped tubes.


I couldn't find the timestamp of it, but if my memory serves me, then he also said that the TA-10 shone with some "special tube" but he would be perfectly happy with the TA-20 on stock tubes. Not at all denying those stock tubes are meager at best and immediate candidate for rolling, but more taken as a queue as to how initial listening would have some wow factor.


hmscott said:


> For me the stock TA-26 was stuck on stock tubes for a couple of weeks until I could get new tubes plugged in, and I often went back to my TA-20 simply because I thought the TA-26 stock tubes as still new sounded too harsh - but, much better than the TA-20 stock tubes sounded to me, and with the TA-26 wide sound stage and "airy tubiness" being much better than most TA-20 tubes sound.


That's insightful, thanks.


hmscott said:


> *The DAC output attenuation, even as little as -3.0dB, -6.0dB or -9.0dB might be enough to help you reduce the harshness you are hearing during new TA-20 / new tubes burn-in.  Trying playing around with the DAC attenuation starting at -3.0dB and increase attenuation until the harshness is reduced as well as possible.  Of course, increase the volume on the TA-20 as needed to return the listening level to where you like it.  Nothing beats actual hours burn-in time, but I can make the harshness more tolerable during burn-in by reducing the drive input to the amp.*


My DAC runs at -9.0 dBFS by default. That also meant that I had to dial the volume know to around the 70's to get a decent volume. I thought that higher volumes from the amp would also incur more distortion from the amp -- a balancing game. So I changed my DAC to 0 dBFS and now volume around the 60's. No change.


----------



## hmscott (Mar 29, 2022)

roderickvd said:


> Well, much appreciated!


NP, my pleasure 


roderickvd said:


> Yes, you may be on to something there. Edit: I also find it lacking in authority and presence, is that something recognizable?


Yup, no presence or authority, and no "slam" or "dynamics", it's "flat".

Those words don't mean much without experience with their opposites 

Which takes running many tubes through your amp, taking the time for them to burn-in and take time to heat up to stable unchanging sound - several hours usually - with 70F ambient, longer or not at all in a heat losing ambient.


roderickvd said:


> It's true that I'm new to this tube game. The scientist in my has long pulled me towards the "best amp is a wire with gain" kind of thinking. It's that thinking that also led me to build my AMB β22, which may be considered reference depending on which standard you hold it to, and pulls out every technical trick in the book. But I have come to realize that this is not truly what I'm after -- at the end of the chain, I prefer that warm, lush sound of my dad's 70s setup so to speak. And here I am getting into tubes.


Yup, the sterile sound can be boring.  Comparing against tubes with flat sterile sound will show better resolution in the SS amp, but against tubes with dynamics and slam, with a wide sound stage and "airy tubiness" will make that sterile SS amp pale in comparison.  My Topping A90 was always that way, sterile, but very accurate sounding, with my FiiO M15 in "Over Ear mode" - high current mode - would sound oh, so much more enjoyable than the A90, and now the TA-20 and TA-26 shine with even more edifying sound.

Truly, listening with the Heerlen Tubes in the TA-20, and more so on the TA-26 with the 7236+5692/Melz or 7236/Jan 6AS7G+Kenrad VT-231 is awe inspiring with music and video soundtracks I enjoy.

Remember the old adage, "Those who expect an outcome will find a way of making that outcome happen."

You can find tubes that will always make that SS amp sound "better", but you can also find plenty of tubes that will make you very happy to have tried the TA-20 and have started on the tube amp path.

And, that will hopefully lead to a nice all Tube amp like the TA-26 with equally excellent tubes like a Domino Plate 5998, or Tung-Sol/Cetron 7236, or Bendix 6080WB with Ceramic Spacers and Graphite plates - this is where the Slam/Dynamics solid support comes from in the TA-26, the power tube.  Then the Preamp tube needs to be as you like it, a CBS-Hytron 5692 gives solid presentation + sparkling highs, VT-231 Tung-Sol Black Beauty (Black Glass) again with solid presentation + less sparkling highs, or a Melz 6N8S with super extended highs... lots of fun tuning and endless swapping - with a very wide sound stage and "airy tubiness" only found in a few tubes in the TA-20.


roderickvd said:


> Yes, those are the ones. The babies were once intended for use in guided missile systems aboard highly dynamic platforms like navy ships. Unsurprising then, that they have excellent linearity, low noise and low microphonics. Again I may have fallen into the trap of technical prowess when in fact something mellower would better suit my ears... it's like a constant source of conflict between the mind and the heart
> 
> Then there's a bit tongue in cheek too -- I work in the defense sector so imagine the coffee talk at work where I'm ever so proud to announce that guided missile technology has now found its way into my hifi equipment


Yes, searching for the same attributes you admire in SS amplification with bring you right back to the sound of SS amplification - but that isn't all there is with Tube amps, if you find the right tubes.  Once you find them and hear them, you will know what we are saying, and then you can help others to find that nirvana level of sound too 


roderickvd said:


> Here's a question that might show my newness to this tube game: aren't all PSVANE's new production? If so I do not understand why they also appear on other lists, sometimes quite well rated (and sometimes not so).


It is all done within the comparisons made available to them, to each of us, we are comparing our previous experience against our new experiences, it is all relative to something, it must be so to rate one above or below another experience - including our own personal favorite aspects of the sound as well, which might be very different than others experiences.

And, the same tubes may sound different in different tube amplifiers, especially when put into different applications, with different design parameters and as such we can only compare tubes using the same equipment we are using ourselves, which is why I try to find actual TA-20 and TA-26/DV 336e reviews of tubes, so that their opinions and comments can apply to our needs.  That isn't always possible, so averaged ratings are sometimes all we have to reference.

As quoted in my previous post, under that top 12AU7 ratings list, they say:

"DISCLAIMER: This is not a definitive list of all best and worst 12au7. It’s purely based on over 5,000 ratings submitted by the users of this site."

Within their ratings, these tubes are rated accordingly.  Other lists, sites, persons, may of course find other attributes more enjoyable for them, causing tubes to be rated in a different level and order within their respective lists.


roderickvd said:


> Doing that now. Also realizing that investing in a pair of top tubes later on should be on the list -- once this unit has proven its worth to me to do so.


And, that is the tough part.  I had enough faith from my short experience listening to better and better new reissue and cheap used NOS tubes to know I needed to "up the ante", but from more reading and searching on eBay over months of comparing what tubes I was looking for were selling, that I could find a good price if I wanted to wait, or a slightly more expensive cost if I didn't want to wait, it is that simple.

You don't need to spend hundreds or thousands for a pair of rare tubes - the scarcity of a tube doesn't necessarily indicate the quality of sound you will get out of the tubes - some people collect rare tubes simply to have rare tubes, and then there are the hoarders, and speculators that raise the price for profit, ruining access to those of us looking for "our sound" to listen to music.

All of these tubes cost under $10 new, some a little more, but none of the 12xx7 tubes cost more than $50 new - so that is where I put my target price for tubes for the TA-20, a max of $50 each, or $100/pair, $200/quad - remember to buy extras of the tubes you really enjoy - they aren't making them any more and they do wear out.  Having a couple of pair for backups is cool, having hundreds of pairs may indicate you want to be a tube dealer or speculator, long term.

Unfortunately the TA-26 "top sought after tubes" will require a bit more "top end" flexibility.  About $150/tube seems to cover the ones I realistically want, while others like the 7236 can be had for $35-$50 "New in Box".

YMMV... please come back and let us know how you enjoy those $1000-$2000 GEC tubes in your future TA-26 amp 


roderickvd said:


> I couldn't find the timestamp of it, but if my memory serves me, then he also said that the TA-10 shone with some "special tube" but he would be perfectly happy with the TA-20 on stock tubes. Not at all denying those stock tubes are meager at best and immediate candidate for rolling, but more taken as a queue as to how initial listening would have some wow factor.


I know, it's tough slowing down and listening carefully and critcally to what he is saying without jumping to already established conclusions, but please give it a try again at the link "time" above, or here again starting at 108 seconds in to the video.


roderickvd said:


> That's insightful, thanks.


Thanks, then you will want to re-read my post as well as re-listen to Zeos's words starting at that 108s time stamp to get some more fun insights, among others:

Zeos says that even with the stock tubes that the "topography" of sound that the TA-20 provides over the single-ended TA-10 is apparent.  Not that the TA-20 stock tubes sound good.  In fact he follows that statement up immediately with "swapping stock tubes may provide an end-game of sorts", and later he says he will swap tubes before bringing it to the meetup/show where he wants to demonstrate the TA-20 dual tube sound vs the TA-10 single tube sound.  Of course using 3 of the same tube would be a fairer comparison, and taking the time to make sure all of those tubes and TA-10/TA-20 are fully "burned in" before showing them off, would be most fairest.


roderickvd said:


> My DAC runs at -9.0 dBFS by default. That also meant that I had to dial the volume know to around the 70's to get a decent volume. I thought that higher volumes from the amp would also incur more distortion from the amp -- a balancing game. So I changed my DAC to 0 dBFS and now volume around the 60's. No change.


Well, then with your set up you aren't overdriving the TA-20.  Your single-ended output must be 2.0V or thereabouts, vs my Topping D90 MQA XLR output of 4.0V.  For a single-ended RCA output from a DAC, 2.0V is the standard output, and not high enough to cause a distortion problem.  Perhaps my tips will come in handy when you get that balanced output DAC... with similar 4.0V output.

Have fun


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## roderickvd (Mar 29, 2022)

hmscott said:


> Yup, no presence or authority, and no "slam" or "dynamics", it's "flat".
> 
> Those words don't mean much without experience with their opposites


Oh, fear not, I know 


hmscott said:


> Unfortunately the TA-26 "top sought after tubes" will require a bit more "top end" flexibility.  About $150/tube seems to cover the ones I realistically want, while others like the 7236 can be had for $35-$50 "New in Box".
> 
> YMMV... please come back and let us know how you enjoy those $1000-$2000 GEC tubes in your future TA-26 amp


I'm pretty sure *that's* never going to happen  although a TA-26 indeed is on my list for later.

In a totally different class I am also interested in a Little Dot MKVIII SE. It's an attention-grabber for sure, and has four times the power of a TA-26, but the SNR of 96 dB leaves me unimpressed. Compare that to the 110 dB of the TA-26. Quite a feat for an OTL, I'd say.


hmscott said:


> Zeos says that even with the stock tubes that the "topography" of sound that the TA-20 provides over the single-ended TA-10 is apparent.  Not that the TA-20 stock tubes sound good.  In fact he follows that statement up immediately with "swapping stock tubes may provide an end-game of sorts", and later he says he will swap tubes before bringing it to the meetup/show where he wants to demonstrate the TA-20 dual tube sound vs the TA-10 single tube sound.  Of course using 3 of the same tube would be a fairer comparison, and taking the time to make sure all of those tubes and TA-10/TA-20 are fully "burned in" before showing them off, would be most fairest.


Thanks for spelling that out for me, you're right. It's a pity there's no fair comparison of the TA-10, TA-20 and TA-26 there. Thought it was surprising for him to compare the TA-26 to the Darkvoice 336 but not even mentioning the other TA's.


hmscott said:


> Well, then with your set up you aren't overdriving the TA-20.  Your single-ended output must be 2.0V or thereabouts, vs my Topping D90 MQA XLR output of 4.0V.  For a single-ended RCA output from a DAC, 2.0V is the standard output, and not high enough to cause a distortion problem.


The single-ended output of a dam1121 is in fact as low as 1.4V RMS even at 0 dBFS.

I see the D90 has an output impedance as low as 100-300Ω. The dam1121's is 640Ω and I believe my upcoming Ares II to be 1250Ω or thereabouts for XLR. I haven't been able to find the input impedance of the xDuoo's, but if that's on the low end then that could also account for a lack of dynamics when paired with a high output impedance DAC.


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## hmscott (Mar 29, 2022)

roderickvd said:


> Oh, fear not, I know
> 
> I'm pretty sure *that's* never going to happen  although a TA-26 indeed is on my list for later.
> 
> ...


The GEC tubes are in that rarity/cost range where you'd need to have "true dedication" to your "obsession". 

Yup, at one time the Little Dot MKVIII SE was on my list too...I'm eyeing other steps up in Amps for later down the road, but for me the TA-20 and TA-26 have "outmoded" the Little Dot amps and the Dark Voice amps I was looking at.  Those brands are nice though, and I know many enjoy them. 

For a lower priced step up upgrade to the TA-26, I've "discovered" the dual mono *La Figaro 339* - which uses the same tubes as the DV 336e/TA-26, but 2x the number!  I'm now buying in pairs... sigh.
Xduoo?  Are you there?  How about a dual-mono upgrade to the TA-26?  Something like a TA-52?  

Zeos doesn't want to be that kind of reviewer, but he tries to expose a wide range of equipment in an easy to take form for many to access.  Zeos also had a "Tube Week" not that long ago, including the TA-26 and mentions of other Xduoo Tube amps, for those of you that have missed them you might enjoy them, if not, please keep it to yourself - we already know he's not the best reviewer - he says so himself all the time...but, everyone, please do post your favorite tube amp reviews, Xduoo especially On Topic here, but hey, what do you like??

```
Xduoo TA-26 _(Z Reviews)_ --Start of Tube Week--
https://www.youtube.com/watch?v=dYe0SxWvi8o
```


```
Miltra OTL PCL86 _(Z Reviews)_ Future Tubes from the Future
https://www.youtube.com/watch?v=YzCcw_qbq8M
```


```
McIntosh MHA200 _(Z Reviews)_ 💎U.S.A. Tubes💎
https://www.youtube.com/watch?v=ik0MMdgZiN4
```
I sent an email to Xduoo asking a few questions, but I used links back here to ask them, so I think I need to ask again explicitly in the email, I'll try again soon 

One of those questions were the impedance of the outputs on the TA-20/TA-26.  But, from usage, I think the headphone outputs are very low impedance - as I can listen to my low impedance IEM's, Planars, but not so for dynamic headphones as my 16 ohm DT-770's sound flat and weak on the TA-26, while the IEMs/Planars rock on the TA-26.  The 16 ohm DT770 sounds great on the TA-20!


----------



## Silver Wolf

Not looked at the TA-26 but the TA-20 output impedance is 4.5 ohms and TA-30 is just under 3 ohms (can't remember exactly but from memory was 2.7 or 2.9 ohms )


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## roderickvd (Mar 29, 2022)

hmscott said:


> Yup, at one time the Little Dot MKVIII SE was on my list too...


What happened? Mitigating the risk of going off-topic, perhaps what drew you to the xDuoo's instead?


hmscott said:


> Zeos doesn't want to be that kind of reviewer, but he tries to expose a wide range of equipment in an easy to take form for many to access.  Zeos also had a "Tube Week" not that long ago, including the TA-26 and mentions of other Xduoo Tube amps, for those of you that have missed them you might enjoy them, if not, please keep it to yourself - we already know he's not the best reviewer - he says so himself all the time...but, please do post your favorite tube amp reviews, Xduoo especially On Topic here


I know. I missed those tube reviews of his, will check them out. At the same time you're very right, when you start hunting for those popular tubes you see prices going up fast. Much more fun poking around the likes of eBay, seeing what's being offered and see what you stumble on. Of course, having a wish list to cross-reference them to.


hmscott said:


> I sent an email to Xduoo asking a few questions, but I used links back here to ask them, so I think I need to ask again explicitly in the email, I'll try again soon
> 
> One of those questions were the impedance of the outputs on the TA-20/TA-26.  But, from usage, I think they are very low impedance - as I can listen to my low impedance IEM's, Planars, but not so for dynamic headphones as my 16 ohm DT-770's sound flat and weak on the TA-26, while the Planars rock


Oh, that'd be great. I'm particularly interested in the *input* impedance too but let's talk output impedance.

The output impedance of the TA-20 was measured on ASR as 4.5Ω. That's not great but not bad either. I like to leave a damping factor of 10x so you should be safe from 45Ω onwards. A ratio of 8x is good enough so you should be safe even with those modern 32Ω cans (well, almost...)

I haven't seen the TA-26 measured, but we can estimate it. Given a typical 6N5P transconductance of 4400 mΩ, you'd expect an OTL output impedance of 227Ω. Now with common damping factors that's rather tough to match. And also non-intuitive: if this were true, would all OTL designs not suffer from poor parings? The EE is explained here on ASR. Management summary: those damping factors are common wisdom for low impedance outputs, not when matching high impedance output with high impedance loads.

I forgot to ask: any experience with rolling the coupling caps in these amps? I saw one forum member having tried Mundorf MCap Classics, and not hearing any improvement immediately after. I don't find that surprising, first because the standard MCaps aren't better of perhaps worse than the stock ELNA SILMIC's -- already quite good! Second because such caps need burn-in very much.

Staying within the Mundorf brand I would look at the SUPREME EVO line (looking at the oil and silver/gold ones as money allows). Not only are they excellent caps by themselves, they are also half the size of what's normal, allowing for greater spacing between them. That means lower capacitive coupling and so lower crosstalk.

Then perhaps sprinkling in some small-package bypass caps.

Just rambling here. Again wondering if more of you have had any cap rolling experience?

Edit: @hmscott I also looked at the La Figaro 339. Initial thought: awesome! Two seconds after: wait, a *dual mono setup* with *a single XLR-3 output*_?_ That's just silly. By having a shared ground you're throwing away the benefits that a true balanced amplifier give you (well, one major aspect anyway). Not saying balanced headphones are the holy grail, but here the entire thing might as well have been single-ended.


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## hmscott (Mar 31, 2022)

Lifetime speaking, I've done enough parts choosing! 

And, although I've looked into it, I'm not really interested in modifying my amps, or building from scratch, I've thought about building from kit - like an 300B/2A3 SE POWER AMP KIT [ TU-8900E ], but I don't need that right now.

I'm happy with the TA-20/TA-26 base design and build as they are right now.  I selected the TA-20 as between the lower priced options I thought it was the best price to benefit choice for me.  I could spend more, but probably not get much more, and I could spend less, but not get that Hybrid tube sound with SS compatibility with headphones.

I wanted more power, but I had the Topping D90 MQA so I didn't need another DAC, and so the TA-30 wasn't of interest with 3W vs the TA-20 2W.  After months of enjoying music on the FiiO M15 and Topping D90/A90, I was ready to try the TA-20, and it has been a fine base to work from to reacquaint myself with tubey sound.

Right now I've got my 2nd wind with the TA-26, so I can continue to enjoy tube tuning, without changing the base builds, although when I settle on my "end game" tubes, I might pull out the specification sheets and re-wire the resistor/cap/inductor/transformer values to match the "final tube" selection(s).

Then again I'm just as likely to swap in a new base system and start over again with the tube rolling - I need somewhere to put all those extra "pairs" of tubes I'll have soon.  

I would be interested in hearing what you get up to with TA-26/TA-20 modifications, and perhaps even try the changes  that you feel make a positive difference, so please do carry on posting your progress.

Nice to meet you, I hope you hang around and get some good use out of your TA-20 

PS: That is why I like using the Tung-Sol/Cetron 7236 Power tube, it has a transconductance rating of 12,500 uMhos, for a slightly lower output impedance, and they can be found without too much waiting for $35-$60 each.  There are other choices as well, for both tube positions on the TA-26:

For 6AS7G tube rollers here .....
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

The Reference 6SN7 Thread
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/

*Update: Forgot to mention about the Tube Week - AMP sound demos!!  Listening with the TA-26 + 7236 + Kenrad VT-231 + Hifiman HE6SE V2...*

TUBE AMP DEMO! // McIntosh Vs Xduoo Vs Miltra
​


----------



## YanaMJ

I've tried the stock tubes, JJ gold, Sylvania /Tung Sol US,  Brimar UK and now Philips Heerlen and clearly theses tubes are my graal 😍😍😍😍 so in love with them


----------



## -Darkstar-

hmscott said:


> Totally agree, and for me the TA-20 sound kept improving all during the first couple of months of use, and that was about the time I found the Tung-Sol 12AU7 Black Glass tubes and stopped listening to the Topping A90 completely - except for specific comparisons to answer questions posed to me online.  Now, the A90 is sitting unplugged under the TA-20...
> 
> I would expect the TA-30 to need as much burn-in time too.
> 
> For me the stock TA-26 was stuck on stock tubes for a couple of weeks until I could get new tubes plugged in, and I often went back to my TA-20 simply because I thought the TA-26 stock tubes as still new sounded too harsh - but, with the TA-26 wide sound stage and "airy tubiness" being much better than most TA-20 tubes sound, even while the harshness played out during burn-in.


The TA-30 was very rolled off and flat sounding at first. The bass was quite loose. This wasn't too objectionable with my Ananda's, but it quite bad with my TH900Mk2's. I ended up having to turn up the amp too much to bring out the mids and the bass would get completely out of control with some material, with terrible resonance off the cups. Now, it pairs quite well with everything, but I think the Ananda has the best synergy with it. I think I'm going to try out some Psvane tubes with it.


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## hmscott (Mar 31, 2022)

-Darkstar- said:


> The TA-30 was very rolled off and flat sounding at first. The bass was quite loose. This wasn't too objectionable with my Ananda's, but it quite bad with my TH900Mk2's. I ended up having to turn up the amp too much to bring out the mids and the bass would get completely out of control with some material, with terrible resonance off the cups. Now, it pairs quite well with everything, but I think the Ananda has the best synergy with it. I think I'm going to try out some Psvane tubes with it.


There are different "levels" of tube grades with PSVANE as with many manufacturers - as some wise person once said, they have to sell all of the tubes they make, even if they are really bad. It helps to learn the methods of how bad tubes are marketed and sold as well as how each detail of their history helps illuminate their achievements, and what they are and how to find them for purchase.

It helps to do some patient research, as there isn't always all of the models and information in one place, so I searched through various outlets for sales of PSVANE before putting together what I thought would be their best models, some kinds of their tubes there are lots of options like with the 6SN7, and some there are fewer.

Also it helps to know that PSVANE is really now Shuguang - as - briefly - some engineers split off from Shuguang to form PSVANE and then PSVANE ended up buying Shuguang and carrying on their less expensive lines of products as well - at some point the lines started to blur between the production lines - and I think the specialness of PSVANE tubes disappeared without their culling process and factory matching - those boxed matched tubes may be no more in their current lines but either they still make the old models in those boxed sets still, or they made a boatload of them and are still selling them - another adage, not everything "new" is designed to be "better". 

What about the rectifier tube in the TA-30? Does it have an affect on the sound qualities of the TA-20?  That is usually why a tube is brought in as a stage in the build of such amps, so what tube brand/models bring what kind of sound in the TA-30?

Some histories of PSVANE, it helps to look at the dates they were written:

WHO ARE PSVANE?
https://www.hificollective.co.uk/components/who-is-psvane.html

Who is Psvane?
https://premiumvacuumtubes.com/who-is-psvane/

Psvane Acme Series (new flagship series)
https://www.whatsbestforum.com/threads/psvane-acme-series-new-flagship-series.26395/post-532813

And, of course PSVANE has splinter groups that have grown up to make good products too.

About [LINLAI™ Global] – The official LINLAI™ EXPORT website
https://linlaiglobal.com/

If you find other accounts of any Chinese tube company history, please do post them.

I've found a lot of unexpected PSVANE models/packaging and variants via searches on Aliexpress.com
General match search
https://www.aliexpress.com/wholesale?catId=0&SearchText=psvane+tube
Focus on newest
https://www.aliexpress.com/wholesal...esale&SortType=create_desc&groupsort=1&page=1
Focus on lowest price
https://www.aliexpress.com/wholesal...olesale&SortType=price_asc&page=1&groupsort=1
Focus on highest price
https://www.aliexpress.com/wholesal...lesale&SortType=price_desc&page=1&groupsort=1
Focus on sales volume
https://www.aliexpress.com/wholesal...ortType=total_tranpro_desc&page=1&groupsort=1

Each one and summed together, helps me focus in on variations within tube types, pricing, which shops to Follow, etc.


----------



## roderickvd

hmscott said:


> And, although I've looked into it, I'm not really interested in modifying my amps, or building from scratch, I've thought about building from kit - like an 300B/2A3 SE POWER AMP KIT [ TU-8900E ], but I don't need that right now.


I'd love to build a kit! I looked at the Bottlehead options, but they're not cheap as they are, and then adding to that EU VAT and import taxes and it just starts getting out of hand. Pity. I didn't know about Elekit, but they seem to be shipping from the EU as well. Will check them out for sure.

From a _very_ quick read on Google it seems that the headphone out of those units is drawn from the speaker output with a series resistor. Technically that's not the greatest way of doing things and usually indicative of "speaker first, headphones second" approach. With a 90Ω resistor, there may be damping issues, _but_ I've also quickly seen great reviews when paired with headphones. Whatever works, works -- I'll do some further digging.


hmscott said:


> I wanted more power, but I had the Topping D90 MQA so I didn't need another DAC, and so the TA-30 wasn't of interest with 3W vs the TA-20 2W.  After months of enjoying music on the FiiO M15 and Topping D90/A90, I was ready to try the TA-20, and it has been a fine base to work from to reacquaint myself with tubey sound.
> 
> Right now I've got my 2nd wind with the TA-26, so I can continue to enjoy tube tuning, without changing the base builds, although when I settle on my "end game" tubes, I might pull out the specification sheets and re-wire the resistor/cap/inductor/transformer values to match the "final tube" selection(s).
> 
> ...


I'll think about rolling caps again once I've decided to keep this unit. They are 8.2µF, and there are four of them, so problem is that good caps get crazy expensive fast -- almost half the worth of the unit itself if you were to go the Mundorf SUPREME or EVO Oil route, or better. I do know from experience that this can really make a difference with removing any "veil" in the sound.


hmscott said:


> Nice to meet you, I hope you hang around and get some good use out of your TA-20


Likewise!

When investigating cap options, I also think I worked out the input impedance to be 20KΩ balanced or 10KΩ unbalanced. With 8.2µF caps, that would put the -3 dB crossover point at about 2 Hz for a more or less linear response from 20 Hz upwards. That's on the lowish side (for comparison: my AMB β22 is 1MΩ) but satisfactory even for highish output impedances.

The same holds for the TA-10. For the TA-26, I couldn't make out the capacitor values from the photos.


hmscott said:


> PS: That is why I like using the Tung-Sol/Cetron 7236 Power tube, it has a transconductance rating of 12,500 uMhos, for a slightly lower output impedance, and they can be found without too much waiting for $35-$60 each.  There are other choices as well, for both tube positions on the TA-26:


Pretty good!


-Darkstar- said:


> The TA-30 was very rolled off and flat sounding at first. The bass was quite loose. This wasn't too objectionable with my Ananda's, but it quite bad with my TH900Mk2's. I ended up having to turn up the amp too much to bring out the mids and the bass would get completely out of control with some material, with terrible resonance off the cups. Now, it pairs quite well with everything, but I think the Ananda has the best synergy with it. I think I'm going to try out some Psvane tubes with it.


Meanwhile I have received my Denafrips Ares II. After a few hours of listening purely over XLR yesterday evening, the TA-20 sounded _much_ better than the night before! The grain was gone, but now I hear recessed vocals and a somewhat flat bass (lack of low end).

I'll try to post more listening impressions tonight, including a comparison of unbalanced versus balanced input, to see if this improvement is due to burn-in of the TA-20 and tubes, or the change to a balanced input. Easy enough to A/B test, with that input selector on the TA-20.


----------



## roderickvd

So... only a few days in and the TA-20 indeed does seem to be opening up and starting to shine!

Comparing RCA and XLR inputs from the same DAC, the XLR input does lift some of the veil that is present on the RCA. This is not a proper ABX test of course and not exactly level matched (although the RCA and XLR volumes are _very_ close when set the same on the dial -- interesting!) but it's also no surprise that opamps touch the sound. So use XLR inputs when you can for maximum sound quality.

But to be honest, the change in SQ between RCA and XLR was much lower than I had expected. Indeed it seems that the biggest improvement comes from burn-in.

I even swapped to my reference AMB β22 and on a quick comparison I must say it sounds close. At this moment the β22 has some more authority at the bottom end still, but the TA-20 sounds more natural with instruments like flute. Not that the β22 sounds ragged by any means (!) but the TA-20 does seem to soften up the edges. As for attack and decay of transients, they sound _very_ close. Impressive -- when this TA-20 continues going this way, it does look like it's going to be a keeper!


----------



## Ufanco

Been having a blast with trying out tubes this week. I bought a lot on ebay of semi used 12au7 most in the 80-90 range. There was a bunch of Westinghouse/Conn 12au7 untested in the lot. Checked them out and they work and sound great have some extras if anyone wants a set to play with PM me.
I found a thread on here that compares a bunch high end 12au7 tubes It’s definitely worth a look. Have to scroll down for the tube reviews.

https://www.head-fi.org/showcase/cypher-labs-prautes-headphone-amplifier.25706/


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## hmscott (Apr 1, 2022)

Ufanco said:


> Been having a blast with trying out tubes this week. I bought a lot on ebay of semi used 12au7 most in the 80-90 range. There was a bunch of Westinghouse/Conn 12au7 untested in the lot. Checked them out and they work and sound great have some extras if anyone wants a set to play with PM me.
> I found a thread on here that compares a bunch high end 12au7 tubes It’s definitely worth a look. *Have to scroll down for the tube reviews.*
> 
> https://www.head-fi.org/showcase/cypher-labs-prautes-headphone-amplifier.25706/


As long as you don't use a headphone/IEM that shows "HISS" - caused by Cathode decay by-products being deposited on the Grid over time, then you will be able to use those tubes for quite a while.

I also did a similar buy of inexpensive used tubes at first with 85% as the "bottom", then when I heard "HISS" - a lot of it btw - a wall of HISS in my IEM's after switching from Headphones, I moved to hunting for cheap 95% Life remaining tubes, but even those have a low level of HISS already, so now I get 100%+/100%+ tubes - I don't buy as many tubes because they are much more expensive - unless you persist with watching/hunting for good prices, which I've been fortunate to find.

It is a lot of fun though getting all those tubes on the "cheap", and in headphones that don't detect the HISS background noise they can sound great - because they are "well burned-in".

*Note: *Found the place in the thread with all of the great tube info, search AS AN UPDATE AS OF 3-3-22 and you'll get there directly, as it is a long scroll to get there otherwise.

@roderickvd - I fixed the 12,500 uMhos 7236 Specifications sheet link posted in my last response to you:
https://frank.pocnet.net/sheets/127/7/7236.pdf


----------



## -Darkstar-

hmscott said:


> What about the rectifier tube in the TA-30? Does it have an affect on the sound qualities of the TA-20?  That is usually why a tube is brought in as a stage in the build of such amps, so what tube brand/models bring what kind of sound in the TA-30?


A rectifier tube will most definitely affect the sound. A slower reacting one will soften and warm up the sound, compared to a quicker reacting one. This is one of the reasons I was intrigued by this amp, because you don't see too many tube rectified amps at this price range. I've had good results with new stock tubes from EH, SED and Gold Lion in the past, and I'm considering them, too. I also might go NOS but only at a certain price point.


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## hmscott (Mar 31, 2022)

-Darkstar- said:


> A rectifier tube will most definitely affect the sound. A slower reacting one will soften and warm up the sound, compared to a quicker reacting one. This is one of the reasons I was intrigued by this amp, because you don't see too many tube rectified amps at this price range. I've had good results with new stock tubes from EH, SED and Gold Lion in the past, and I'm considering them, too. I also might go NOS but only at a certain price point.


That's great!

I haven't any experience with that tube, but found this link that suggests a variant that might be easier to find in NOS:

"My own amp had a 5Z3P, which can be directly replaced with a 5U4G. This gave me a bit more output voltage and ability to add a slightly bigger R/C filter to the B+ rail. Don't think it made any major difference to the sound, but it looks better..."
https://www.diyaudio.com/community/...cements-for-chinese-tubes.110365/post-1329618

It looks like there are a wide range of 5U4G NOS options 
https://www.ebay.com/sch/i.html?_nkw=5U4G&_sacat=0&_sop=16

A Western Electric 422A or 274B would be an awesome replacement - but a bit ridiculously priced 

Listing at the bottom of the 1st page from the above ebay search are a couple of 110% testing RCA 5U4G's for only $59!, you only need one - one has a cracked base, not unusual in these very old tubes:

NOS new testing matched pair 5U4G made by RCA
https://www.ebay.com/itm/394006997428

GE 5U4G Coke Bottle RADIO/AMP RECTIFIER Vacuum Tube TESTED Vintage S.4173-D
https://www.ebay.com/itm/154556067571

There are others scattered over the first 1-4 pages, and even more if you consider $200 and below. 

I would also ask Xduoo directly if they have any recommended variants for the 5Z3P that they have tried in the TA-30, and if any of those tubes above would work ok in the TA-30.


----------



## ColSaulTigh

Best inexpensive option is the BRIMAR 5Z4GY variant: https://www.ebay.com/itm/310653909306?hash=item48546a793a:g:fHcAAOSwJPph8-RM  Big, Bold sound, incredibly fast, thick and meaty, plenty of airness in the top end. No sluggishness.....but it's a little nuclear reactor.  It runs HOT!

Best $50 you'll spend...


----------



## ColSaulTigh

If you really want to go nuts - pop for a pair of these, too: https://www.ebay.com/itm/254301528939

This setup (currently in my bedroom) performs ALMOST as well as my Woo Audio WA6-SE stuff.


----------



## hmscott (Apr 1, 2022)

ColSaulTigh said:


> Best inexpensive option is the BRIMAR 5Z4GY variant: https://www.ebay.com/itm/310653909306?hash=item48546a793a:g:fHcAAOSwJPph8-RM  Big, Bold sound, incredibly fast, thick and meaty, plenty of airness in the top end. No sluggishness.....but it's a little nuclear reactor.  It runs HOT!
> 
> Best $50 you'll spend...


That is awesome!  Do you know if the any of the other 5U4G variants I linked above are compatible with the TA-30?

What other power tube variants have you heard are compatible with the TA-30?

I would ask Xduoo, but I already have a couple of unanswered questions in the queue with Xduoo.  Sometimes they get so busy it takes a while to get an answer, but they always applogize (they don't need to!!) for their sometimes slow responses.  I really appreciate their support 


ColSaulTigh said:


> If you really want to go nuts - pop for a pair of these, too: https://www.ebay.com/itm/254301528939
> 
> This setup (currently in my bedroom) performs ALMOST as well as my Woo Audio WA6-SE stuff.


Yup, the E80CC's made in Heerlen, Holland (Netherlands) are in my top 5 favorites on the TA-20!

Do you have startup considerations with the TA-30 with the E80CC's installed?

In the TA-20 when the ambient gets much below 68F the TA-20 "errors" on startup because the E80CC's take longer than the built-in startup timer on the TA-20, but if I restart quickly 2-3x on the last power on the TA-20 works fine with the huge E80CC's.

Right now I have a pair of the Haltron E80CC's made in Heerlen, Netherlands installed and they start up without fail - it is warm enough now for them to heat up fast enough, before the TA-20 built-in startup timer expires.


----------



## hmscott (Apr 1, 2022)

roderickvd said:


> ...Meanwhile I have received my Denafrips Ares II. After a few hours of listening purely over XLR yesterday evening, the TA-20 sounded _much_ better than the night before! The grain was gone, but now I hear recessed vocals and a somewhat flat bass (lack of low end).
> 
> I'll try to post more listening impressions tonight, including a comparison of unbalanced versus balanced input, to see if this improvement is due to burn-in of the TA-20 and tubes, or the change to a balanced input. Easy enough to A/B test, with that input selector on the TA-20.


Awesome, congratulations on the new Denafrips Ares II - I'm assuming that needs about 100-200 hours of burn-in too? 

Aha!, Denafrips does a 100 hour burn-in at the factory!:
https://www.denafrips.com/support#:~:text=All DENAFRIPS DACs are factory,tests performed prior packing & shipment.

"Factory Burn-In
All DENAFRIPS DACs are factory burn-in for at least 100 hours with comprehensive Audio Precision Tests, QAQC tests performed prior packing & shipment."


roderickvd said:


> So... only a few days in and the TA-20 indeed does seem to be opening up and starting to shine!
> 
> Comparing RCA and XLR inputs from the same DAC, the XLR input does lift some of the veil that is present on the RCA. This is not a proper ABX test of course and not exactly level matched (although the RCA and XLR volumes are _very_ close when set the same on the dial -- interesting!) but it's also no surprise that opamps touch the sound. So use XLR inputs when you can for maximum sound quality.
> 
> ...


That is great!  I'm happy for you that your TA-20 is ripening nicely!

The potential for tonality balance changes through tube rolling, and as those new tubes burn-in the mellowing and softening of their rough edges, provides an ever changing and engaging listening experience.

As I recall, I had about the same experience with my Topping A90 sounding more resolving than the Brand New out of the box TA-20 with stock tubes, but with burn-in time on the TA-20, and a few tube rolling's, my TA-20 soon matched and surpassed the Topping A90 in my resolution perception, and more importantly in listening enjoyment.

On my TA-20 the difference in perceived volume level differs by about 4-5 steps in the volume indicator.  Listening to Tidal right now, and Balanced at 65 sounds the same as 70 on single-ended, listening with the Hifiman HE6SE V2.

Using the 6.35mm single-ended output I can go as high as 79-80 - it is too loud if I go any higher.  Balanced is maxxed-out for me at 74-75.

As far as which is better?, I find the TA-20 4-pin Balanced output is more detailed and slams a bit harder, but I happily listen via 6.35mm/3.5mm single-ended often, and to me the single-ended 6.35mm output sounds great!


----------



## roderickvd

To be clear I was A/B testing RCA/XLR in, each time XLR out.

The more I'm leaning towards keeping it, the more I'm thinking about doing so with a good tube. I think my current Sylvania 6189W's may be a bit hi-fi sounding, and would perhaps welcome something warmer, lusher. I can get my hands on a matched pair of Philips Heerlen E80CC's (gold pins) for $75 including shipping... seems like a great deal?

I can get also get pairs of Philips SQ E80CC for even less, but not measured and so no guarantees about matching.


----------



## hmscott (Apr 3, 2022)

roderickvd said:


> To be clear I was A/B testing RCA/XLR in, each time XLR out.


Yup, the RCA inputs are where the opamps pre-process the signal before going on to the tubes vs straight through to tubes for the XLR input.  That is where you might detect a difference in the sound, but as you've found the difference is minimal if not unnoticeable.  The grain was from the raw new TA-20/stock tubes, and disappears after a few days, and continues to grow into more awesome sound over the first couple of weeks, or more if you swap tubes a bunch of times as I did. 

I was commenting on the sound quality and output level differences between the 4-pin and 6.35mm output headphone jacks, with XLR input for both.  Often prospective/new TA-20 owners ask if there is a sound difference between the two outputs, and it is good to know there can be a level difference between outputs, even with the same input.


roderickvd said:


> The more I'm leaning towards keeping it, the more I'm thinking about doing so with a good tube. I think my current Sylvania 6189W's may be a bit hi-fi sounding, and would perhaps welcome something warmer, lusher. I can get my hands on a matched pair of Philips Heerlen E80CC's (gold pins) for $75 including shipping... seems like a great deal?
> 
> I can get also get pairs of Philips SQ E80CC for even less, but not measured and so no guarantees about matching.


I'd say that $75/pair for Philips Heerlen E80CC's (gold pins) is an amazing price, and the kind of deal I wait for to pounce on!  Hopefully it is still there for you!


Spoiler: eBay tube buying experiences...



In general I try to stay away from sellers that don't list specific test results, and also stay away from sellers that don't accept returns, but I make exceptions in specific cases, as described below:

If the item is on eBay I make sure the seller has great feedback - I look for 100% positive feedback or very close to it.  I also read previous buyer feedback looking for problems going back 12 months about items similar to what I am buying, like not getting what buyer expected is the main one I look for.  Sometimes the great deals aren't what they seem and feedback can show that.

Today I ran across a bunch of "mislabeled" 6080WB listings that say they have graphite plates, but from the photo's they clearly do not have graphite plates.  There were a surprising number of mislabeled listings.  But, there was one that was mislabeled a 6080WB and the photo's showed it was a Sylvania GB6080, a very rare "special" tube from their "Gold Bond" line, so even the mislabeled items can turn out to be "gems".

If the listing says "New" or "New - open box", or "New - Other" and the items are said to be "NIB" or from a case of new tubes, and the photos either show the full case or if there is an individual box per tube or per pair(s) - military JAN brown/white box labeled with Government contract numbers, date, etc - then often the seller doesn't test or match as that is too much effort for a whole box, and they wait for the buyer of a specific tube/qty to ask for testing.  Even so I've run across sellers that don't have testers or refuse to test before sending, but as long as they accept returns and have great feedback I'll give them a shot.  I've found some great sellers this way.

Over time you get used to eBay and how to read sellers, and I've not had any "bad" transactions/situations where I've lost $ or got stuck with a "wrongly listed" product.  I have had to return a few times because the seller couldn't test the tubes before sending them, and the tubes were actually "DOA" - happened 2x so far - or they don't meet my needs as stated to the seller before purchase.  For example I suggest they test with IEM's before sending, if they hear HISS those aren't for me and I would send them back, but sellers won't take the time to test with an IEM, it is outside their normal testing experience.

For me I let them know I buy New 100%+/100%+ tubes because I listen with IEM's a lot of the time, and they exhibit HISS in tubes that have time on them, the hot/heated cathode emits particles that deposit on the Grid and other places inside the tube creating a background HISS that builds over hours with the heater powered on - or rarely new tubes can have a manufacturing defect that introduced contamination causing the HISS in New tubes (?).  Either way, I cannot keep tubes if they HISS, and I've found starting around 95% "Lifetime remaining" my most sensitive IEM's exhibit HISS and at 85% and lower I hear a "WALL of HISS" well over the level of the music, so those tubes aren't usable by me.

I bought my 5 pair of "E80CC HALTRON TUBE RÖHRE LAMPE VALVE NEW 5 PCS 6085" for 300 Euro, from a seller on the Spain eBay site, which in todays $ is $331.02/10 = $33.10/tube or $66.20/pair.  Also a rare find.  We negotiated the price down from his price of 75 Euro/tube ($41.38) if I bought all 5 pair.  He didn't list measurements, but I saw in his photo's on listings he had a tube tester, so I kindly asked him if he would test for GM/mA for each  tube and write it on a slip of paper and put the slip in each tube box with the tube.  All the tubes measured way over 100%!  He was a great seller, but he hasn't had anything since that I need... sigh.


So, you might ask how many pairs he has available, and see if you can get the price down even more!

Yup, that is a great deal at $75/pair, as I normally see them go for 2x-3x as much, and much more.  And, the other tubes - as long as they are "New" untested that is still a good possibility of getting great tubes.

Untested "Used" tubes are a gamble that I stay away from, as I've learned they are cheap for a reason, and so they aren't worth it for me to try.

Good luck!  And, please let us know what you end up getting and how you like them


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## roderickvd

Thanks. Very valuable advice.

I contacted the seller and they are on my way. He has a good reputation and provided screenshots of his test results, 101/98 and 103/104, so I feel I just so happened to stumble upon a great deal. And he’s promised to run through his inventory again to see if he has any more pairs like this too.


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## Ufanco

Has anyone used the 12bh7 in there Xduoo ta20? Currently using a pair on amperex ecc82 or pinnacle 13D5a. So far liking the sound on the pinnacle 13D5a the most.
The rca cleartop and northern electric aren’t half bad. Even the Westinghouse/Conn tubes sound much better than stock. So fair haven’t had issues with hissing. Kinda surprise since using iem to listen.

https://tmraudio.com/accessories/miscellaneous/roller-hero-tubility-belt/


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## hmscott (Apr 3, 2022)

Ufanco said:


> Has anyone used the 12bh7 in there Xduoo ta20?


There might not be anyone here that can answer that with first-hand experience, but the determining factor for compatibility - for otherwise compatible family tubes of 12xx7 is the Heater Current.  If there is an increase of Heater current over the stock tube, can the transformer and the rest of the power supply handle the added load?

I asked Xduoo each time before I tried a new tube variant in the TA-20 and TA-26 via service@xduoo.com, but I think I can save you the time as I have heard a few people say that they have used the 12BH7 in the TA-20/TA-30 successfully and were really enjoying them.

In fact I was on my way to trying the 12BH7 in my TA-20 when I got the E80CC Heerlen / Haltron tubes, and then I received the TA-26 and started on that tube buying path.

I had already checked tube specification sheets that the 12BH7 drew the same Heater current as the E80CC, and Xduoo confirmed that the E80CC's double Heater Current of the 12AU7 was within the capability of the TA-20 to support.

The stock 12AU7 uses 150mA or .150A of current x2 = 300mA or .3A for their Heater Current.  The E80CC draws double the Heater Current per tube of 300mA or .3A per Tube, so 2 E80CC's draw .6A or double the .3A of 2x 12AU7's.

And, the 12BH7 specification also shows a 300mA or .3A Heater Current draw per tube, the same as the E80CC, which Xduoo approved of in the TA-20 

Here is my post listing Xduoo's approval and mentioning the headroom for Heater Current draw in the TA-20:
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16731642

August 4, 2021, relayed through Hifigo from Xduoo:
"Hello, Scott,
Sorry for late reply. E80CC ( 6085 ) is ok to match with TA20 and TA30 Xduoo replied, and they thank you for your questions and testing.
If you have any futher questions, pls let me know.
Best regard ~ "

Here are the specifications sheets for the 12AU7, E80CC, and 12BH7 so you can see their respective heater current specifications.

So, yeah, go ahead and try some 12BH7's in the TA-20 and please let us know what you tried and how they sounded 

Here are a couple of tube rolling articles or posts on the TA-20 or TA-30 - both use 12xx7 compatible tubes with the same limitations, that list the 12BH7:

Tube Rolling the Xduoo TA-01b TA-10 and TA-20 12au7 Amps
https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/




And, I have so many times found I hear the reviewers tubes the same... or different - YMMV 

"Im using RCA 12bh7 tubes and some Matsushita Japan 12BH7A in one of mine right now. Been running them about a year to see how well it holds up. Definitely like them better than any of the 10 or so different 12AU7 tubes I've tried including the Brimar CV4003."
https://www.audiosciencereview.com/...headphone-amplifier-review.10118/post-1008905

"If you are really into it, 12BH7 is better than 12AU7 for less."
https://www.audiosciencereview.com/...-headphone-amplifier-review.10118/post-420267

This is a different amp, but it is using 12AU7's and the observations are interesting, another thread I read up on before deciding on trying the E80CC/12BH7 in the TA-20:

Topic: Driver rolling: 12BH7s, E80CCs and 6SN7s  (Read 13295 times)
https://forum.bottlehead.com/index.php?topic=3501.0

And, then one step to the side, there is another 12BH7 variant that others have also mentioned using in place of the 12AU7, and that is the 13D6, here is a listing (out of stock) for the Brimar 13D6, that describes it as "Perhaps one of the best 12BH7 tube"
https://www.tubemonger.com/MINT_NOS_MPs_60s_13D6_12BH7_BLACK_PL_STC_ENGLAND_p/939.htm

As I haven't tried a 12BH7 or a 13D6 yet in the TA-20, but going on similar experience, it is tough to tell what is going to sound great.  Some say "Black plates", some say "Grey plates", and yet others say Long/Tall Plates while others say "Short plates", and plenty of combinations in between.  I've been surprised by short grey plate 12AT7's that sound amazing - and Tall Black plates that are also great sounding, so it really is on a tube make/model by tube basis.

There are a lot of great 12BH7's out there 
https://www.ebay.com/sch/i.html?_from=R40&_nkw=12bh7+tube&_sacat=0&LH_ItemCondition=1000|1500&_sop=16

Everyone is on their own path of experimentation and has their own favorites, there is a lot to experience when tube rolling on the path to your own personal audio Nirvana. 

*Update: *Tubemonger really has a lot variety and in their premium tube category a lot of listings, with some still in stock 
https://www.tubemonger.com/category_s/64.htm <= Premium category
https://www.tubemonger.com/category_s/64.htm <= New arrivals, I sorted by Newest once into that link, and found:

Amperex Philips E80CC 6085 SQ - 1970 Special Quality MINT NOS NIB *Gold Pins Heerlen Holland ADZAM Label* - Same Date Batch (Singles/M. Pairs)
A little pricey at $120/tube though...Quantity in Stock:18
https://www.tubemonger.com/Amperex_Philips_1970_NOS_NIB_E80CC_6085_Gold_Pins_p/1315.htm

Looking at the size/internal structure the E80CC looks a lot like the 12BH7, and the E80CC is a beast mode 12AU7


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## Ufanco

hmscott said:


> There might not be anyone here that can answer that with first-hand experience, but the determining factor for compatibility - for otherwise compatible family tubes of 12xx7 is the Heater Current.  If there is an increase of Heater current over the stock tube, can the transformer and the rest of the power supply handle the added load?
> 
> I asked Xduoo each time I tried a new tube variant in the TA-20 and TA-26 via service@xduoo.com, but I think I can save you the time as I have heard a few people say that they have used the 12BH7 in the TA-20/TA-30 successfully and were really enjoying them.
> 
> ...


 Going read the link you sent me much appreciate it for taking the time to respond.


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## ColSaulTigh

hmscott said:


> That is awesome!  Do you know if the any of the other 5U4G variants I linked above are compatible with the TA-30?
> 
> What other power tube variants have you heard are compatible with the TA-30?
> 
> ...


Sorry I haven't replied sooner - I read this one and forgot to post a reply.

Pretty much any 5U3X/5U4XX variant should work.  You can also run 274B (I think, need to test) and GZ34 (again, I think, need to double-check).  Here's an article on tube rolling the TA-30 that's a pretty in-depth read: https://audiofool.reviews/tube-rolling-the-xduoo-ta-30/

I have had no startup issues whatsoever with my TA-30.  I run my bedroom at 64*F at night, and have never experienced a single error.  The TA-30 heats up plenty fast, and is ready to go by the time I climb into bed and put my Sennheiser HD-8XX on.


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## hmscott (Apr 3, 2022)

ColSaulTigh said:


> Sorry I haven't replied sooner - I read this one and forgot to post a reply.
> 
> Pretty much any 5U3X/5U4XX variant should work.  You can also run 274B (I think, need to test) and GZ34 (again, I think, need to double-check).  Here's an article on tube rolling the TA-30 that's a pretty in-depth read: https://audiofool.reviews/tube-rolling-the-xduoo-ta-30/
> 
> I have had no startup issues whatsoever with my TA-30.  I run my bedroom at 64*F at night, and have never experienced a single error.  The TA-30 heats up plenty fast, and is ready to go by the time I climb into bed and put my Sennheiser HD-8XX on.


That's great.  I think I recall Xduoo saying something about the TA-30 not needing a "resister" change that they suggested I could make on the TA-20 to extend the startup pre-heat timer long enough to heat up a cold tall tube like the E80CC, and possibly the 12BH7.

Early on I used my Topping A90 to "pre-heat" the TA-20 - I let the A90 run and heat up the TA-20 and then the E80CC was warm enough to start within the stock timer delay.

Summer is coming soon enough, it is warm enough here already to warm up the TA-20 enough to start the E80CC without triggering the "Protect" light.

Thanks for the TA-30 power tube info, there really is so much to explore if we want to, or listen to awesome music and video audio.


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## roderickvd

hmscott said:


> That's great.  I think I recall Xduoo saying something about the TA-30 no needing a "resister" change that they suggested I could make on the TA-20 to extend the startup timer long enough to heat up a cold talk tube like the E80CC and probably the 12BH7.


Do you know which resistor that was, and to which value it should be changed?


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## hmscott (Apr 3, 2022)

roderickvd said:


> Do you know which resistor that was, and to which value it should be changed?


Yes, and I am happy that you asked 

Here is the first answer back from Xduoo, with Hifigo translating, I'll include both the original Chinese answer and the Hifigo English translation.  I'll put it in a spoiler bracketing because we are supposed to keep to English in posts here on head-fi.org, the 1st question I asked was the E80CC Protect question:


Spoiler: First response



"Hi Scott,

Thank you for your detailed questions and Xduoo are very happy to reply you . Here is the some reply from Xduoo,  let me try to translate.

问题1：是的，我们在国内也发现有一些用户更换胆管会出现"Protect"字样，原因是E80CC需要预热的时间更长，因此需要调整电路的保护时间，把时间调整得更长一些，明天我上班让工程师跟我讲一下改哪里的电阻，就改一颗电阻的阻值就可以了。

Q1: yes, we also find some users with Protect problem, the reason is it need preheat more, so we need to adjust the protection time longer, we will check with engineer how to change the value of resistance  and come back to you.

问题2：没有OPA， TA-20的电路架构是胆管放大+晶体管甲类扩流。
Q2: There is no OPA, TA-20 circuit structure is the tube amplifier plus " the transistor type A expands current"

问题3：最佳阻值我们要换上12AT7测试一下

Q3: the best resistance we need to test it with 12AT7

Many thanks for your testing and let's try more together. "

I already covered the 2nd question here in the thread, which was about how Opamps are used in the TA-20, and would Opamp rolling to pick a "better" Opamp improve the audio quality.

As covered here before, the XLR input doesn't go through Opamps, the audio goes directly from XLR input to the Tubes, and then directly to the discrete transistor amplification stage and directly to the XLR/RCA outputs.  The Opamps only come into use on the RCA inputs, and then only to convert to a balanced input to feed the Tubes directly, and from the Tubes the same path to the discrete transistor amplification which goes directly to the RCA/XLR output.  Balanced end to end in both paths, with the Opamps acting as the convertor from single-ended to balanced on RCA inputs only.

The 3rd question I haven't covered much in the thread because we didn't get an answer back yet - I should follow up and ask again and reword my question with more description to clarify what I was asking - basically should we pick different interface resister/capacitor fixed values to the tube socket when switching from 12AU7 to 12AT7, and would it help to have switchable banks of values when changing tubes to match differing tube specifications.


Hifigo was very helpful throughout to act as a liaison between my questions and Xduoo's answers so that we could have a more productive exchange, and it has worked out very nicely, I want to thank them all very much for their patient assistance 

Here is the answer to question #1, where the resister value and a photo of where the resister is to change to extend the timer for physically larger tubes like the E80CC / E180CC, and possibly the 12BH7 - although I haven't tried a 12BH7 yet myself:

"Hi, Scott
Thank you for your efforts, change the value of this resistor (R116) from 100KΩ to 200KΩ or 470KΩ. The larger value, the longer the protection time.



*Best Regards,"*


Spoiler: More info if interested



I'm not set up here with space or equipment where I am staying to open up the TA-20 and change the SMD resister myself - and then to further test which value provides an optimal delay in startup to give tubes with the "longest warm up requirement" enough time to warm up before the TA-20 measures characteristics during startup to know whether the tube is "warned up enough" to come online.

If a TA-20 owner is experiencing the Cold ambient temperature "Protect" light at Startup with an E80CC or E180CC or perhaps a 12BH7 - basically tubes with a larger glass envelope surface area and a larger cathode / grid / plate surface area that needs more time to come to operating temperature - and wants to do "value picking" of that startup timer resister value, please post your results here in this thread, and I'll feed that info back to Xduoo for their own testing.

I think that not enough people are letting Xduoo know they are experiencing this error for them to update the design.  Changing the value would make the TA-20 startup longer for everyone else too, so a general change might not be optimal.  This could be another "switchable" value change for allowing a wider range of tube rolling.  This last paragraph is speculation on my part, I haven't discussed it with Xduoo.

I should also mention that even though Xduoo said that they have had reports like mine of the Protect light coming on during cold ambient temperatures with the E80CC tubes, I haven't heard of anyone else here on head-fi.org report such an experience except myself.

I hope this info helps someone - although I don't as a matter of course suggest that most people need to start changing the internals of their equipment, if you have the electronics experience, surface mount rework soldering experience (not necessarily one in the same), and a strong enough desire to stop restarting their TA-20 + E80CC/E180CC tubes in cold weather a couple of times to get the "Protect" light to stay off - then here is what to do to resolve that inconvenience.

I haven't felt motivated enough to pursue the change myself, but perhaps someone else will, or I might change my living situation where I can set up my equipment and experiment with the SMD resister values myself.


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## roderickvd

Thanks. I have a decent soldering and hot air station, but I'm not too keen on messing with SMD resistors either.

My E80CC's should be coming in this week. Like you say, let's first see if it turns out to be a problem at all. My amps are in the heated living room anyway.


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## hmscott (Apr 3, 2022)

roderickvd said:


> Thanks. I have a decent soldering and hot air station, but I'm not too keen on messing with SMD resistors either.
> 
> My E80CC's should be coming in this week. Like you say, let's first see if it turns out to be a problem at all. My amps are in the heated living room anyway.


Then you shouldn't see any problem.  When I have the E80CC/E180CC tubes installed I don't see the TA-20 "Protect" light come on when the ambient temperature is normal/warm, only when it is uncomfortably cold.


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## roderickvd

Philips Heerlen E80CC's are in! As most probably already know, the TA-20 tube protectors don't fit over them. I had no start-up issues. 

By the way, the Sylvania JAN 6189W's (triple mica) I had in previously did start to sound extremely good after +/- 40 hours on-time. Earlier I wrote they might sound a bit hi-fi and depending on what kind of sound you seek, that might as well be a compliment. Extremely well balanced with a touch of softness compared to my AMB β22. I very much enjoyed listening to them the past evenings.

These NOS E80CC's are again a bit harsh on initial listening. Let the burn-in commence


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## ColSaulTigh

roderickvd said:


> Philips Heerlen E80CC's are in! As most probably already know, the TA-20 tube protectors don't fit over them. I had no start-up issues.
> 
> By the way, the Sylvania JAN 6189W's (triple mica) I had in previously did start to sound extremely good after +/- 40 hours on-time. Earlier I wrote they might sound a bit hi-fi and depending on what kind of sound you seek, that might as well be a compliment. Extremely well balanced with a touch of softness compared to my AMB β22. I very much enjoyed listening to them the past evenings.
> 
> These NOS E80CC's are again a bit harsh on initial listening. Let the burn-in commence


I love my Philips Heerlen E80CC's - along with the 1957 NOS JAN Sylvania Ruggedized 5931/5U4GB rectifier, the TA-30 is a mighty powerhouse with lots of precision and slam on demand!  It's almost too bad it's on my nightstand and not a primary amp.  But I've got Woo's for that...


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## Ufanco

roderickvd said:


> Philips Heerlen E80CC's are in! As most probably already know, the TA-20 tube protectors don't fit over them. I had no start-up issues.
> 
> By the way, the Sylvania JAN 6189W's (triple mica) I had in previously did start to sound extremely good after +/- 40 hours on-time. Earlier I wrote they might sound a bit hi-fi and depending on what kind of sound you seek, that might as well be a compliment. Extremely well balanced with a touch of softness compared to my AMB β22. I very much enjoyed listening to them the past evenings.
> 
> These NOS E80CC's are again a bit harsh on initial listening. Let the burn-in commence


I seem to remember a post awhile back that someone used a 3d printer to make an extension for the protecter to raise them up. I use socket savers so I also not able to use mine. Plus I ordered a couple pairs of the 12BH7a to try out, so should have some thoughts on them next week. 
Right now using either the Pinnacle 13d5a or the Amperex ecc82 holland tube depending on my mood and music I’m listening too.


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## ColSaulTigh

Ufanco said:


> I seem to remember a post awhile back that someone used a 3d printer to make an extension for the protecter to raise them up. I use socket savers so I also not able to use mine. Plus I ordered a couple pairs of the 12BH7a to try out, so should have some thoughts on them next week.
> Right now using either the Pinnacle 13d5a or the Amperex ecc82 holland tube depending on my mood and music I’m listening too.


Reverse them so they're pointing outward instead of inward.


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## roderickvd

ColSaulTigh said:


> Reverse them so they're pointing outward instead of inward.


The tube protectors on the TA-20 you mean? Either I'm going to have a huge "a-ha" moment but I don't see how...

Ran into two consecutive "protect" lights during start-up today.


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## hmscott (Apr 6, 2022)

roderickvd said:


> The tube protectors on the TA-20 you mean? Either I'm going to have a huge "a-ha" moment but I don't see how...
> 
> Ran into two consecutive "protect" lights during start-up today.


Yup, it happens usually early in the morning before the heat has been turned on.  I have mine far from a window, but if you have the TA-20 near a window I can imagine the proximity cold conduction would drop the temperature on the TA-20 metal chassis quickly too, even in a warm room.

The key is to quickly switch off/on right when the Protect light comes on, otherwise the tubes will cool down quickly.  I've not had to do more than 2 back to back starts when I sit there and watch for the Protect to come on and then quickly switch off/on, otherwise before that I needed to do 3 in a row - if I leave a large enough gap between switch on/off's.

Oh, yeah, during the cold weather - even with the heat on - there is a cold presence in the air such that if I turn the amp off during the day, I will experience Protect again when I turn it on, so I leave it on during the cold weather.

But, it is worth the considerations to get that great sound!  And the E80CC/E180CC's Heerlen are much cheaper than the 100's/tube that the similarly great sounding 12AU7's demand, or these Telefunken ECC802S:

2x ECC802S = 12AU7WA Telefunken <> pair Röhre tube Valvola NOS NEW NEU #8930
https://www.ebay.com/itm/334279007650


ColSaulTigh said:


> Reverse them so they're pointing outward instead of inward.





roderickvd said:


> The tube protectors on the TA-20 you mean? Either I'm going to have a huge "a-ha" moment but I don't see how...
> 
> Ran into two consecutive "protect" lights during start-up today.


The Post Frames that plug in over the tubes, on the TA-20.

On most E180CC I can fit the tips of the tubes into the "hole" in the Apex of those Post Frames, but the E80CC and likely the 12BH7's will be too tall.

So you turn the Post Frame "upside down" - you can't then plug it into the Post Holes in the TA-20 while they are "upside down", instead you turn their aspect around so that you can "horseshoe" around each the Tube.

The Post Frames will slide around instead of being "protectively solid", but they will be there as a reminder to be careful when working around the tubes.

Also plaicing the on the TA-20 in somewhat protective pose is a nice way to not "loose" the Post Frames when not in use.


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## roderickvd

I must be daft but I don't see any other way to insert the two frames. Could you share a picture?


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## hmscott (Apr 7, 2022)

roderickvd said:


> I must be daft but I don't see any other way to insert the two frames. Could you share a picture?


Forget about inserting them 

You flip them over and "lay them on their tops" onto the TA-20, oriented such that each open V slides around the tube - with the open end of the V pointing inward - around the tubes.

This way they are "out of the way", and won't get lost, plus their mere presence has saved me from getting burned a couple of times, as my hand reaches for the power switch, or the Flashlight I have perched on top of the HE-1 perced on top of the TA-20... sorry I don't have a photo available


Ufanco said:


> I seem to remember a post awhile back that someone used a 3d printer to make an extension for the protecter to raise them up. I use socket savers so I also not able to use mine. Plus I ordered a couple pairs of the 12BH7a to try out, so should have some thoughts on them next week.
> Right now using either the Pinnacle 13d5a or the Amperex ecc82 holland tube depending on my mood and music I’m listening too.


If no one has done created a design file for it yet, someone could do a 3D scan of each post and design a plan that includes extensions of the legs an Inch or so - measured against an inserted E80CC/12BH7.

I haven't seen a post mentioning a file for an extended Post Frame object file for the TA-20, or an Extended Bottom Plate object file for the TA-20... please share them here if you find them.


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## ColSaulTigh

hmscott said:


> Forget about inserting them
> 
> You flip them over and "lay them on their tops" onto the TA-20, oriented such that each open V slides around the tube - with the open end of the V pointing inward - around the tubes.
> 
> This way they are "out of the way", and won't get lost, plus their mere presence has saved me from getting burned a couple of times, as my hand reaches for the power switch, or the Flashlight I have perched on top of the HE-1 perced on top of the TA-20... sorry I don't have a photo available


There you go.  That's what I was trying to describe.


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## hmscott (Apr 8, 2022)

@Ufanco - I've been looking for 13D5's since you mentioned them, and first I found these gems:

Brimar 13D5 - 1960s MINT NOS NIB Industrial 12AU7 Long Plate - England (M. Pairs/M. Quads/Singles) - LAST CALL
https://www.tubemonger.com/BRIMAR_13D5_Industrial_12AU7_Long_Plate_England_p/433.htm

But, I missed their "Last Call", they are out of stock! Noooo!! 

And, then I found these, too bad they only have 9,822 in stock (!!)

13D5 12AU7 ECC82 VINTAGE BRIMAR NOS VALVE TUBE - £40.00​https://www.langrex.co.uk/products/13d5-ecc82-vintage-brimar-nos-valve-tube/

Anyone want to try them and report back here?  And, please don't buy all 9,822 of the 13D5 tubes; Please leave some for the rest of us next month. 

I've already blown my discretionary budget for this month, at least I got these tubes for my TA-26:

RCA JAN CRC VT-231 6SN7GT Tubes Smoked Glass 1944/1945 [1 Pair]
https://www.ebay.com/itm/304391750983

And, these:

Tungsol 6080WA Power Tubes Equivalent 6AS7 #126
https://www.ebay.com/itm/255376750602


----------



## roderickvd

Ah I see.


hmscott said:


> If no one has done created a design file for it yet, someone could do a 3D scan of each post and design a plan that includes extensions of the legs an Inch or so - measured against an inserted E80CC/12BH7.
> 
> I haven't seen a post mentioning a file for an extended Post Frame object file for the TA-20, or an Extended Bottom Plate object file for the TA-20... please share them here if you find them.


Ah, I see. I prefer them without sliding parts then, it’s my navy background


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## Ufanco

hmscott said:


> Forget about inserting them
> 
> You flip them over and "lay them on their tops" onto the TA-20, oriented such that each open V slides around the tube - with the open end of the V pointing inward - around the tubes.
> 
> ...


Here is some info on 3d printed riser.
https://www.head-fi.org/threads/xduoo-amplifiers.682282/page-22


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## roderickvd

Awesome!


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## hmscott (Apr 7, 2022)

Ufanco said:


> Here is some info on 3d printed riser.
> ...


Thank you @Ufanco for finding the 3D riser posting !


synfinatic said:


> I'm using some socket savers in my TA-20 so 3D printed some risers for the guards.
> 
> 
> 
> ...


Hi @synfinatic , those are some awesome beefy risers for the TA-20 tube guards!

Would you please provide a link to upload the design/printable file(s), so we can print some too?
Also, we've been talking tubes for a while here lately, and wonder what tubes you've rolled and enjoy.


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## Ufanco (Apr 7, 2022)

Just received my 12BH7a tubes so I can also confirm they work with the Xduoo ta20. There still warming up but Initial impressions are really good. One thing noticed right of the bat is the tube glow is much brighter than any of the 12au7 tubes. Kinda nice with the lights dimmed down.
Will add some additional comments after I spend more time with them. Need to do more research on these tubes there Sylvania 12BH7A black plate square getter the one has a red tip.


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## hmscott (Apr 7, 2022)

There are differing views of what the "Red Tips" indicate, most suggest they are "better" tubes culled for some specific need, like medical, aviation, laboratory, low noise - many interpretations.  Certainly there is no "standard", people had various paint colors to indicate local/particular needs so they used them.  I've seen green, yellow, and... red, in a much differet context.

I knew a friend that used Red nail polish to paint the Tube Tip to indicate "bad" tubes!  Yup.  And, several repair technicians that put "used"/"replaced" tubes into the nice clean new box the replacement tube came in, with no particular markings on those "bad" tube box to indicate they were bad tubes...Open box to be sold? 

There are many gotchas when buying tubes... I should probably get a nice reliable tube tester --- one of these days

Brent Jesse's audiotubes.com has several mentions of Red/Green tip tubes:

MATCHED PAIRS 12AU7/ECC82 Telefunken, Grass Valley or Textronix *medical grade RED and GREEN tip* SELECTED TUBE MATCHED PAIR diamond mark, VERY RARE!
New Old Stock in white boxes. These are the nearly extinct SELECTED TUBE that were selected by Grass Valley or Tektronix for use in sensitive stages of ECG machines or test equipment. *The red tip (and some manufacturers used green) identifies the tube as having passed intense quality screening for critical applications.* Low noise and no microphonics were just two of the attributes to qualify these for exacting test and medical equipment use. These wonderful vintage tubes are vanishing at an alarming rate. A fantastic, long-lived tube with unequalled sound quality. These are hand selected and matched to within 2 percent transconductance. *Both red tip and green tip type, and Tektronix selected tube label are usually available. They are the exact same grade tubes. *The cream of the crop, better get some now! SINGLE TUBES ARE $200.00 EACH. $400.00 per pair - in stock search in page on http://www.audiotubes.com/12au7.htm

12AU7 Mullard Medical Grade series, *red tip or Tektronix Selected*, Great Britain. New Old Stock White Box.  Beautiful old Mullard ECC82 types SELECTED TUBES in the *famous "red tip"* or *Tekronix Selected Checked Tube series*, these were low noise screened for demanding industrial or medical use.  Some say these are the best 12AU7 ever, and these have been carefully factory noise tested, essentially military spec.  MATCHED PAIRS ARE $425.00 PER PAIR.  Get some while you can and hear the quality yourself! PRICED PER SINGLE TUBE.  $199.00 in stock search in page on http://www.audiotubes.com/12au7.htm

*12AU7 Mullard Medical Grade series*, LONG PLATE SQUARE GETTER, red tip, Great Britain, MATCHED PAIR. New Old Stock White Box.  The rarest of the Mullard rare medical grade selected tubes are these long plate square getters!   Finding long plate square getters is difficult enough, but to find them as *aftermarket selected medical red tips* is almost impossible.  The first pair I have found in 25 years!  Beautiful old Mullard ECC82 types SELECTED TUBES in* the famous "red tip"* or Tekronix Selected Checked Tube series, these were low noise screened for demanding industrial or medical use.  Some say these are the best 12AU7 ever, and these have been carefully factory noise tested, essentially military spec.  PRICED PER PAIR.  *$675.00  Out of Stock* - search in page on http://www.audiotubes.com/12au7.htm

Jesse doesn't seem to have any "Red" tipped 12BH7's, as there is only 1 listed 12BH7: * 12BH7A $25.00*
http://www.audiotubes.com/bjtubes.htm#main list


----------



## CJG888

I have a pair of Westinghouse red tip 12BH7s. Presumably they were made by Sylvania? They will be rebrands from a US manufacturer.


----------



## CJG888

Could be RCA, I suppose.

Unlikely to be GE. They sound good…


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## Ufanco (Apr 8, 2022)

CJG888 said:


> Could be RCA, I suppose.
> 
> Unlikely to be GE. They sound good…


From my reading the RCA are some of the better 12bh7 tubes. After listening to the 12BH7a I’m impressed. Order some cbs 12bh7a to try. In my system the Sylvania 12BH7a there in my top 3 now there with the pinnacle 13d5 and Amperex ecc82. It’s hard to compare since takes time to change tubes. Plus it’s also what type music i‘m listening too.
Here is a link comparing some of the different 12bh7.
http://oldstockaudio.blogspot.com/2010/05/12bh7-listening-test.html



hmscott said:


> @Ufanco - I've been looking for 13D5's since you mentioned them, and first I found these gems:
> 
> Brimar 13D5 - 1960s MINT NOS NIB Industrial 12AU7 Long Plate - England (M. Pairs/M. Quads/Singles) - LAST CALL
> https://www.tubemonger.com/BRIMAR_13D5_Industrial_12AU7_Long_Plate_England_p/433.htm
> ...



Heard the Brimar 13D5 are a great sounding tube’s.


----------



## vmiguel

I need some help, please, with tubes for a TA-26.
Reading this thread, I've already bought a RCA JAN-6AS7G as a replacement to the 6N5P.

Now, as a replacement for the 6N8P I'm looking at 6SN7 types. Am I correct?
Any advice on specific models? My budget can extend up to 60€.
TIA


----------



## roderickvd

After 60 hours of so burn-in with the Philips Heerlen E80CC's, I just swapped in my Sylvania 6189W's again. I think the E80CC's had a tad too much bloom when paired with my Amiron Home cans. Those already have quite a bit of mid-bass and together it might be a bit too much?

This is hard to A/B test of course, so let's see how it goes.


----------



## hmscott (Apr 9, 2022)

roderickvd said:


> After 60 hours of so burn-in with the Philips Heerlen E80CC's, I just swapped in my Sylvania 6189W's again. I think the E80CC's had a tad too much bloom when paired with my Amiron Home cans. Those already have quite a bit of mid-bass and together it might be a bit too much?
> 
> This is hard to A/B test of course, so let's see how it goes.


Yup, the tough part is waiting an hour+ for the swapped pair to warm up to start critiquing...

Plus it might take more hours than 60, like 200 for those "huge" cathode/grid/plates to seat/burn-off - if I didn't get "pre-burned-in" E80CC's and E180CC's along with the new pairs, I might still not have heard the "best" sound.  My "new" E180CC's were in for weeks before the edge completely came off.

That is why it was so nice to have a backup amp - 2nd (A90), 3rd (FiiO M15), 4th (TA-26) options (5th/6th if I include my BTR5/BTR3k's) to enjoy while running in tubes on the TA-20 side by side in the background.  It can get grating and make the ears overly sensitive or worse - desensitized - if I listen to the tubes with harsh edges all the while they are breaking in.

I had the Amiron Wireless Copper running on wired for many hours, those sounded awesome - until I had to return them due to increasingly flakey Bluetooth connections - it was sad, as I haven't been able to find another set since.

Maybe get a nice inexpensive alternative stack, and even a nice compact BTR5 original/2001 or BTR3k (PS4 compatible), might be nice to have a side system to allow running in tubes for longer periods without needing to check up on them?  Or, is that what you already do?  What is your "backup" system?

Do you have the product/sale link for those particular Philips Heelen E80CC's? If after 200 hours they are still too much you might need to look for other makes/production years.

For example, on the TA-26 all of my NOS 6SN7 variants are pleasant to listen to in all of my headphones/IEM's so far, except for the Russian Melz 6N8S's, they extend far too far into the treble range and with the right (wrong?) headphones/IEM's those Melz as they are now are far too "detailed" to bear - but they are breaking in too, so who knows if they also might trim their sharp edges over time.

It also varys from person to person...you might look into a solution to attenuate or filter out frequencies over a certain range of comfort for you.  I've not had to look into that yet - except maybe the Melz? - so I don't have an immediate suggestion - except look for software filters / equalizer to try to cut the edge so you can enjoy your new edgy tubes while breaking in?


vmiguel said:


> I need some help, please, with tubes for a TA-26.
> Reading this thread, I've already bought a RCA JAN-6AS7G as a replacement to the 6N5P.
> 
> Now, as a replacement for the 6N8P I'm looking at 6SN7 types. Am I correct?
> ...


If you read back in this thread there are lots of comments on tubes tried in various Xduoo Amps, that should help to start...here's a couple with a 1st post with variant listings and additional info:

The Reference 6SN7 Thread 
https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/post-1380036

For 6AS7G tube rollers here ..... 
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-5441008

There are others, but tackling those first posts + reading through those threads - and catching up on current discussions will help too.

I've made a few posts here and there about what I am using in my TA-26, you could search for my posts with TA-26 in them.


----------



## roderickvd

hmscott said:


> I had the Amiron Wireless Copper running on wired for many hours, those sounded awesome - until I had to return them due to increasingly flakey Bluetooth connections - it was sad, as I haven't been able to find another set since.


The Amiron Wireless is closed back, right? I have never heard those. My wired Amiron Home cans are open back. Should sound quite different, I image, although probably both tuned for smooth listening.


hmscott said:


> Maybe get a nice inexpensive alternative stack, and even a nice compact BTR5 original/2001 or BTR3k (PS4 compatible), might be nice to have a side system to allow running in tubes for longer periods without needing to check up on them?  Or, is that what you already do?  What is your "backup" system?


No, I don't have another tube system yet.


hmscott said:


> Do you have the product/sale link for those particular Philips Heelen E80CC's? If after 200 hours they are still too much you might need to look for other makes/production years.


I bought them from here. They were a single pair. Most of the letters fell off but from what there is, the photos are really good:
https://www.marktplaats.nl/v/audio-...1813963766-e80cc-philips-heerlen-matched-pair


hmscott said:


> It also varys from person to person...you might look into a solution to attenuate or filter out frequencies over a certain range of comfort for you.  I've not had to look into that yet - except maybe the Melz? - so I don't have an immediate suggestion - except look for software filters / equalizer to try to cut the edge so you can enjoy your new edgy tubes while breaking in?


I guess it will just take some more time to find out whether it's burn-in or just my personal preference.

At this moment I'm really enjoying these Sylvanias! And indeed it just might be personal preference (plus that already warm tuning of the Amiron Home). Remember I have long listened to pretty high-quality solid state. So my listening neurons are all wired for transparency and speed. Not for a dry, analytical sound, though -- can't stand that. So these tubes may just be a mix of what I know with a bit of added tube softness that SS can miss.

Relevant too may be the source in the chain. Mine has long been R2R, first Soekris and now this Denafrips Ares II. Both with NOS filters (not real NOS, I know, for both of them). Such a DACs sound much warmer and liquid to my ears than the delta-sigma likes of (particularly) ESS and AKM. 

I might open up the TA-20 sometime soon to measure up the caps and see if I can get into cap rolling.


----------



## roderickvd (Apr 11, 2022)

I opened up my TA-20 today and I was surprised both ways.

First, for any of you who are thinking of doing the same, a quick how to. This unit is built *compactly* and so not the easiest to disassemble. That said, it's also not the hardest, but it requires a bit of fiddling.

First, unscrew the bottom plate and everything on the back plate. Now take the bottom plate off and unscrew everything, *except* the four screws that hold the socket raiser and the two screws that hold a strengthening mechanism on the XLR output. Finally, take out the connector between the board and the display.

When you are done, it should look like this:




You may now slightly lift the board near the volume/input knob, then wiggle a little to slide it out to the front. *Take care* to this slowly and gently, you will notice that you cannot take it out entirely because there are connectors from the top of the board (not pictured) going to the power supply section. These function like a leash and at this point you can only angle the board or you will sever those connections and have a lot of repairs on your hands.

If you want to take the board out completely, then you will need to desolder these top connections. Like I said, this unit is not made for tinkering.

Now starting with the bad news, I was dismayed to see a lot of oxidation on the bottom as well as a lot of smears. Obviously this is very poor QC and workmanship from whoever soldered the through-hole components together and forgot to remove the solder flux remains. I don't know if xDuoo will say my warranty is void for opening this unit, but they should thank me for it! The oxidation was pretty severe already and would have caused a short at some point.

Here are some pictures of this very poor performance. I used flux remover on it and it went away immediately.

Note not only the smears in the center but also the white abrasion around the joints on the right:



Abrasion again as well as some thick smears:



See the abrasion in the center? That one almost shorted the two joints!



For anyone reading this from QC, here is the board serial number:



Now for the good news. Without reverse engineering the schematic or claiming to be an expert in amplifier design, it does seem quite a bit of attention has gone into the design of this unit. Here are Nichicon FW caps, judged by their capacitance and voltage rating, used as power supply caps for the solid state section on the secondary side:

\

The FW range is "standard audio grade". We can only hope that these are genuine. Many parts sourced from China are fake. But regardless whether they are genuine or not, these caps are pretty good but there are better ones to be had. Space is limited, though. They are now 16 mm in diameter and 25 mm high. There is a little room to grow, but not much.

The black capacitors in the background must be the coupling caps. They are branded xDuoo and must be standard MKP types. They measure a little over 20x30 mm - quite small actually.. Earlier in this thread someone managed to fit standard Mundorf Map Classic's in there, that are 22x33. That really is about as far as you can go.

That the coupling caps are so close together may be pleasing to the eye but is not best for performance. The closer they are, the greater the capacitive coupling will be, and the greater the stereo crosstalk. Alas, there is no space in the unit to do something about that.

On the other end of a little transformer there are Nippon / Chemi-Con KXG's. From their specifications I assume that these are the tube section on the primary side, although the placement on the board might make you think otherwise. Again not bad:



They are specified to be 12.5 mm in diameter and 20 mm high.

Then I noticed two TDK ZJY-2P01's here. They are common mode distortion filters. Nice to see attention is paid to that:



Finally, the solid state section on the bottom consist of unbranded D882M and B772M NPN/PNP pairs. They actually look like they are MOSFETs instead of plain resistors, good stuff. They read "RZAA" and "FSAA" respectively but there's very little to be found on that. The one and only trail I could find on Google leads to the Hong Kong based MAKOSEMI, which I have never heard of before.

There are four little potentiometers above them that silently scream "do not touch" as they have probably been biased at the factory.



So in conclusion, when we temporarily forget the very poor QC and just focus on the engineering, it does look like xDuoo did not try to build this as cheap as possible, but in fact put some pretty decent components in here and there.

I will try and come up with some ideas for cap rolling. But like I said, space is tight! Any ideas?


----------



## Ufanco

roderickvd said:


> I opened up my TA-20 today and I was surprised both ways.
> 
> First, for any of you who are thinking of doing the same, a quick how to. This unit is built *compactly* and so not the easiest to disassemble. That said, it's also not the hardest, but it requires a bit of fiddling.
> 
> ...


It‘s a shame thats you need to unsolder it to gain access to clean off the solder flux remains. Going just hope the QC was better with mine. Still it was interesting to see inside the TA20 thanks for the pictures along with the detailed description.


----------



## roderickvd

Not sure if I got that across correctly: you can open it and remove most of the flux without desoldering. It’s just that when you want to get the board out completely, say to get on a workbench, then you need to desolder. Otherwise you can but the enclosure upright with the board angled out. Just be sure the enclosure doesn’t tip over because that would surely break something.


----------



## hmscott (Apr 11, 2022)

Althought "messy" / "crunchy" flux seems like something to clean up, it actually doesn't do anything "bad" sitting there.

When I did electronics assembly/rework over a period of 8 years, I went from "must clean up", to "heck it don't matter", and various places in between as the customer requirements varied.

There are some specifications that require completely clean boards/connections - we used to have "baths" to hose down the boards after rework with 1-1-1 Methyl-Ethyl-Ketone, but that is usually reserved for conformal coating - the board solder side is coated, and in some situations the whole board is "dipped".  Adherance of the material to the board and components requires the cleaning, flux instability would destabilize the coatings.  There are other situations where a clean board is required for post inspection QA, during QA they often want to see the rework flagged / tagged - whether to clean before/after is up to their request.

Another consideration is "weight" on builds you want to remove all of the extraneous materials from the build that you can.  Short wires, tight lead clipping without solder encrochment, and removing unnecessary debris - like thick flux and by-products.

I'd leave the flux on unless the solder connection integrity was in question.

Early on when I was deciding on what to purchase, I found a couple of video's on youtube where the guy was intent on finding upgrade components in all of his equipment, and a TA-20 or similar was discected and capacitors were selected to fit - and he found some nice ones - but after they were replaced he didn't find any difference in the audio, which I thought was a bit odd given the quality and quantity of parts replaced.  He never came back with another video, and now I cannot find them on youtube.  But, there is a lot of "Audio capacitor" discussion and speculations.

BTW, a well known "fix" when hearing noise in the TA-20 is tightening up the green yellow stripe ground wire - that thick green wire you can see connected under the bottom plate.  A few have mentioned improving noise by tightening the ground connection.

If you do find replacement capacitors or other components that improve the sound I'd love to hear about them.  So far everyone I've heard from on this subject thinks there isn't enough room in the case of the TA-20, and outboard caps could be a solution... perhaps building a new larger capacity case would be needed to get the best capacitors sized for the task?

You've probably already found these, but here are some mentions of capacitor for the TA-20 / TA-26
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16727359 - values mentioned
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16524266 - mention of outboard caps for TA-26
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16524655 - response showing TA-26 internals photo's and the tight fit for upgrades

I don't see too many mentions here, I had to look elsewhere to find mentions of TA-20 component upgrades, and I haven't really looked for TA-26 component upgrades.

@PetFju - how have your component upgrades gone?  Have you had any additional changes?  How has the sound changed as the caps aged?
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16735640
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16735863

How about you @Wiljen and @AudioCats - did you do any upgrades to components in/outboard of your TA-26's?
https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16524655


----------



## roderickvd

hmscott said:


> Althought "messy" / "crunchy" flux seems like something to clean up, it actually doesn't do anything "bad" sitting there.
> 
> When I did electronics assembly/rework over a period of 8 years, I went from "must clean up", to "heck it don't matter", and various places in between as the customer requirements varied.
> 
> ...


Nice to hear that you've actually been in this industry. I'm not directly, but now one or two things -- probably not as much as you.

It wasn't just the crunchy, salty bits on the PCB. I'm not sure if you could make it out on video but there was even one "bath" (now solidified) or excess flux.

Now I know that not all flux is bad, particularly nowadays with that RoHS flux that is supposedly "no clean". But those "no clean" properties depend entirely on the right application - in the right amount with the right temperature. That doesn't have seem to happened here.

Even the RoHS "no clean" flux is acidic and hygroscopic in nature. Meaning that over time, it can act as either an insulator but also as a conductor, depending on humidity.

All in all not something I want to see on my boards in these gobs!


hmscott said:


> Early on when I was deciding on what to purchase, I found a couple of video's on youtube where the guy was intent on finding upgrade components in all of his equipment, and a TA-20 or similar was discected and capacitors were selected to fit - and he found some nice ones - but after they were replaced he didn't find any difference in the audio, which I thought was a bit odd given the quality and quantity of parts replaced.  He never came back with another video, and now I cannot find them on youtube.  But, there is a lot of "Audio capacitor" discussion and speculations.


I can imagine. To have an audible improvement you would want to replace the parts with ones of much higher quality. But such parts are also much larger. So, within the confines of what you have, you can only step up a notch. For example, from the Nichon FW you could upgrade to the KW series in the same form factor. It'll be a bit better but don't expect miracles. And certainly subject to many hours of burn-in at which point your brain has tilted expectancy too...


hmscott said:


> BTW, a well known "fix" when hearing noise in the TA-20 is tightening up the green yellow stripe ground wire - that thick green wire you can see connected under the bottom plate.  A few have mentioned improving noise by tightening the ground connection.


I have zero noise issues. Never had with any piece of kit by the way, except the surrounds of my Harman Kardon Citation system. And those are ungrounded so probably just have a really cheap PSU and poor wiring layout.

The ground wire in my TA-20 was already nicely tucked in to the very far end of the case, as to minimise any interference with PCB paths and components.

I should add that I run my setup fully balanced, so grounding problems are not to be expected. But all my previous single-ended gear I also have had zero grounding issues. 


hmscott said:


> If you do find replacement capacitors or other components that improve the sound I'd love to hear about them.  So far everyone I've heard from on this subject thinks there isn't enough room in the case of the TA-20, and outboard caps could be a solution... perhaps building a new larger capacity case would be needed to get the best capacitors sized for the task?


I smile at outboard caps because not only do I usually find that pretty ugly, also there is physics at work. The area between the leads of the capacitor acts as an inductive field. The further away the caps, the longer the leads, and the greater the inductivity -- all of which hampering sound quality instead of improving it. So I will definitely stay within the dimensions of the unit.


hmscott said:


> @PetFju - how have your component upgrades gone?  Have you had any additional changes?  How has the sound changed as the caps aged?
> https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16735640
> https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16735863


Thanks for summing those up. I would expect @PetFju's cap change to not be groundbreaking. Probably the xDuoo branded MKP's that are in there are in more or less the same league as the basic Mundorf MCap Classics. It really is a pity that there isn't more room to work with here, because other coupling capacitors would probably be the greatest return on investment.

As for the other caps, I still think its fun to spend some time and money at. I'm evaluating options that might fit including the popular ones from Nichicon and Panasonic.

One thing I wonder is why xDuoo chose to put Nichicon audio caps in there. Those are caps made for in the signal path. Would it in a power supply section be more appropriate to use ones intended for that purpose, like the Panasonic F-series?


----------



## Ufanco (Apr 11, 2022)

Spent the weekend tube rolling and for my setup the 12BH7a are right up there with the 13D5a and possible better it’s kinda a tossup and both out perform the other 12UA7 and even the Amperex ECC82 I have.
The only thing with using 12BH7a is the higher heat so using a 40mm computer fan to bring the heat level down.
I have a pair of CBS 12BH7a coming today there suppose to be nos so going have to let them burn in. Thinking of selling some of the 12ua7 and buying another pair of the sylvania 12BH7a curved black plate. Other thoughts are the rca 12BH7.


----------



## roderickvd

Some more TA-20 teardown.

I forgot to mention two posts ago, but when you look carefully in the picture with the Nichicon's, you can see a Zener diode in the top right. There are two of them there, probably used as voltage reference. I believe that depending on the diode used, this can garner quite a stable voltage. Having two diodes does seem to me that the regulation is non-tracking, i.e. the positive and negative rail each have their own voltage reference. This is usually the case I believe. The only design I know of that does rail tracking is the AMB σ22 DIY PSU. Principally it should not matter if voltages differ a bit, but what you want ideally is that any variances are mirrored. With two Zeners, you don't have that mirroring, and so the rails are not guaranteed to work in unison.

The markings on the two opamps in the center are hard to read but are 2604's. I'm not sure which brand. The full marking reads "BB OPA 2604AU B58JC". Any of those B's could be 8's or vice versa. There seem to be two more opamps at the top in the middle, but those markings are almost completely vanished.



Couple of more capacitors here. These seem to be four 10µF 35V Elna SILMIC II's. These are input caps I guess to block any DC? These Elna's are quite good but I know of even better ones: no input caps at all! I have no sources with DC offset nor have I had ever. I'm new to tubes -- is there anything particular about tube amps that require this capacitance? If not, my experience has shown that removing input caps really improves sound stage.



This picture from the top of the Nichicon's show there is a teeny bit of room to grow. The current ones are 16 mm in diameter. I suspect the outer circle is 18 mm.
You can also see the tiniest bit of space left around the MKP output caps, which I more accurately measured as 22x32 mm.



The Nippon Chemi-Cons really have no space for something larger in diameter:



Again note the two Zeners in that picture, in the corner of the two lower caps.

Now for the room you have in between the PCB and the enclosure, that's just about 39 mm.

 

Note that this is for the back part of the unit. The front is shorter in height, about 29 mm. It's hard to say exactly where this drop in height starts. From what I could see, the Nichicon's are about where the higher ceiling starts.



So there you have it. I tried opening the transformer where I am pretty sure a switching mode power supply resides. But for that I would have to remove the array of RCA inputs which are hot-glued to the top, and now cover two screws to gain access. I didn't feel like undoing that glue so that's where I stopped.

By the way, if it indeed is a SMPS powering this unit as I believe it is, then again there are better caps specifically for SMPS applications than the Nichicons, which are intended for in the signal path.

So brewing on the list:
- replacing the Nichicons for ones on SMPS duty
- bypassing the input caps (any reason not to specific to tube amps?)

And maybe have a look at the Chemi-Cons. Not much wrong with them probably, but who knows.


----------



## roderickvd

Sorry for keeping posting my train of thought.

I've narrowed down the cap choices to this:

Nichicon FW -> Panasonic FR. Low ESR (0,080 -> 0,056) and almost double the higher ripple current (1950 -> 3820). That should work well for SMPS usage. All this in the same 16x25 mm package! My only worry is that the SMPS may become unstable with too low of an ESR, if it was engineered for a specific higher ESR and without proper phase compensation.

Chemi-Con KXG -> Panasonic EE. Only slightly higher (12.5x20 -> 12.5x25) but again with much higher ripple current (390 -> 1290) and lower ESR (0,08 -> 0,06). This one may need a bit of looking around, as it seems to be sold out on the major outlets.


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## hmscott (Apr 12, 2022)

roderickvd said:


> The markings on the two opamps in the center are hard to read but are 2604's. I'm not sure which brand. The full marking reads "BB OPA 2604AU B58JC". Any of those B's could be 8's or vice versa. There seem to be two more opamps at the top in the middle, but those markings are almost completely vanished.


Xduoo's responses to my questions about swapping opamps in the Xduoo TA-20:
https://www.head-fi.org/threads/the-opamp-thread.432749/post-16699436


roderickvd said:


> I've narrowed down the cap choices to this:
> 
> Nichicon FW -> Panasonic FR. Low ESR (0,080 -> 0,056) and almost double the higher ripple current (1950 -> 3820). That should work well for SMPS usage. All this in the same 16x25 mm package! My only worry is that the SMPS may become unstable with too low of an ESR, if it was engineered for a specific higher ESR and without proper phase compensation.
> 
> Chemi-Con KXG -> Panasonic EE. Only slightly higher (12.5x20 -> 12.5x25) but again with much higher ripple current (390 -> 1290) and lower ESR (0,08 -> 0,06). This one may need a bit of looking around, as it seems to be sold out on the major outlets.


The question is, of course, is what would be the effect of changing those power supply caps on the sound of the audio?

As far as removing coupling caps on tubes, it has been done in the design stage, IDT it would be successful only removing the caps - there are other considerations and I recalled reading this thread a while back on DIYaudio when searching for tube info - a great site:

A Tube amp without coupling capacitors? Possible?
https://www.diyaudio.com/community/threads/a-tube-amp-without-coupling-capacitors-possible.341298/

I wish I had the equipment together to participate in a build myself - like a couple of extra TA-20's to experiment on so I could still listen with a functional TA-20 while the other two are pulled apart, but perhaps some other time.

Have fun


----------



## roderickvd

hmscott said:


> The question is, of course, is what would be the effect of changing those power supply caps on the sound of the audio?


Little, probably. On the primary side in particular. On the secondary side though, there is a chance of a small improvement. Those Nichicons are not made to be driven by an SMPS and I’m this case have a 64% higher resistance than the Panasonics. Guess we’ll only know by trying 


hmscott said:


> As far as removing coupling caps on tubes, it has been done in the design stage, IDT it would be successful only removing the caps - there are other considerations and I recalled reading this thread a while back on DIYaudio when searching for tube info - a great site:
> 
> A Tube amp without coupling capacitors? Possible?
> https://www.diyaudio.com/community/threads/a-tube-amp-without-coupling-capacitors-possible.341298/


I know that thread and basically it very much depends on the amp design, whether there is negative feedback or not, also the discussion is a mix of discussion on output, input and interstage coupling caps. 

Principally most OEMs put input caps as an absolute precautionary measure, protecting speakers and cans from damage when DC would be on the input. In my experience this is rarely if ever the case and so it’s a protection that can be removed. Hypex for example had input caps on their UcD models (and bypassing them was a popular mod) but did away with them on the NCores. 

It’s an easy mod to try and should really up the sound quality if the amp is OK with it, or would otherwise lead to very bad distortion or worst case arcing in the tubes. So I’ll try with the stock tubes and a cheap pair of earbuds 

I also ordered some Vishay MKP1837’s 0.01uF to bypass the output caps with. Pretty sure I’ll be able to squeeze them in, and should be a worthwhile upgrade!


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## roderickvd (Apr 13, 2022)

An input bypass mod for the TA-20 is born!



*Warning:* this mod makes the amp DC coupled. Be sure that you do not have DC on the inputs. That usually is the case. But if, just if, there is DC on the inputs now or ever during an output failure of the source, then you can damage your headphones permanently. Obviously this mod is completely at your own risk.

In the picture above I just soldered four jumper leads on the bottom of the board, where the small, gold-and-black colored Elna capacitors are soldered through. On the top of the board these are marked as C122, C123, C124 and C125. You could also cut those capacitors and tie their leads together. That might be easier, but obviously irreversible. Soldering jumpers is a bit more fiddly but allows you to undo the mod when you want. It also has the advantage that you don’t need to remove the board from the chassis, just remove the bottom plate.

To my ears, this mod gives an immediate and significant improvement in clarity, lower end and three dimensionality. Loving this!


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## hmscott (Apr 12, 2022)

It's funny, yesterday I had a scare with inducing a large Pop in my headphones due to a poorly seated FAA-6080WA tube in my TA-26 - 2 different tubes in a row - heads up with 6080's and the TA-26 - they will pull an arc if not seated completely!
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-16912037
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-16912112

Fortunately the surge didn't destroy my headphones, but if I didn't have the Capacitor blocking DC, I wonder if there might have been a different outcome?

After that jarring series of events, I think I'll leave well enough alone...

But, at least you now have a baseline comparison with which to judge your capacitor replacements/upgrades, you can tune for *least* audible degradation as compared to the shorted caps.


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## Ufanco

roderickvd said:


> An input bypass mod for the TA-20 is born!
> 
> 
> 
> ...


Interesting little confused on the whole process so think I better not attempt it. Been super happy with the improvement’s the 12BH7a has bought to my system. Even using the inexpensive cbs 12BH7a made huge improvement to the sound. Highly recommend if you have a TA20 to pickup a set of 12BH7a to try out.


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## roderickvd

hmscott said:


> Fortunately the surge didn't destroy my headphones, but if I didn't have the Capacitor blocking DC, I wonder if there might have been a different outcome?


Principally it would not have mattered. These input caps sit between your source and the tube, not between the tube and your headphones. 

Also arcs can carry both AC and DC components, so a capacitor is not an arc protector perse.


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## hmscott (Apr 16, 2022)

roderickvd said:


> Principally it would not have mattered. These input caps sit between your source and the tube, not between the tube and your headphones.
> 
> Also arcs can carry both AC and DC components, so a capacitor is not an arc protector perse.


The DC components are often the driver killers, but yes I still heard a pop, so there were other frequencies passed.

There used to be output DC blocking capacitors, but now only the first 1-3 stages have them, according to this thread:
https://www.diyaudio.com/community/threads/dc-blocking-caps-in-modern-amplifiers.252752/

So where are the caps you shorted out in your TA-20?  Which stage(s)?  Either way, the idea is to stop DC from passing through the Amplifier to the output, so you don't damage your speakers (headphones).

So you didn't short all of the coupling caps in all of the amp stages?  So DC is still blocked at earlier/later stages?


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## roderickvd

Yes, the big black film capacitors are still there and block DC to the headphones. Can’t really omit those on tube amps (that is what the difficult discussion on diyAudio was about when someone proposed tube amps with no coupling caps).

I totally agree with the statement that DC coupling caps should be on the output and not on the input: https://www.diyaudio.com/community/...ors-are-not-on-every-amp.215832/#post-3085987


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## roderickvd (Apr 14, 2022)

TA-20 mod #2: adding bypass caps to the output coupling capacitors!



_There's a loose piece of solder just above C18 which I removed afterwards. I didn't take a picture after._

Though we have no room to swap the stock output capacitors for something better, we _can_ improve them by adding some bypass caps! Here I have added four Vishay MKP1837 0.01 μF (10 nF) caps, one per output cap. For those who don't know them, they're quite famous as bypass caps -- Google and you will find out this is an audiophile favorite.

The previous mod where I shorted the input caps is easy to know if you can hold a soldering iron, and has a large payoff. This mod is a lot trickier to solder and has a smaller effect, but an audible effect still! It tends to make music sound more natural, with better micro-definition in all registers. Psycho-acoustically this may be perceived as a little brighter, with precise soundstage, more "hi-fi" and less mellow sounding, which depending on your taste may either be a good or bad thing. Your perception may vary of course.

Here's how you do it. Earlier I wrote about how top expose the top of the board in the unit. It would be oh-so easy if we could just solder those Vishays on the bottom but unfortunately we can't: the Vishays are a pinch too thick so the bottom plate would not fit anymore. So at the top of the board they have to go.

There is very little headroom above the existing output caps (those big black film capacitors branded as xDuoo's own). The chassis is recessed there. So what's important is that you tuck them right in between the two pairs of caps, in the little "valley" that's between them. Use a plier to bend the leads outward and try positioning them. If you put the pairs of bypass caps close and to the center of the output caps, you can manage to _just_ have leads sticking out on both ends for both bypass caps.

When you got the position, use some hot glue to hold them in place.

Now finely position the leads. Again because the headroom in the case is limited, it is very important that you keep the leads as low as possible. If they are too high, they might touch the casing and I don't want to find out what happens when you short them to ground like that. Fortunately you have an excellent gauge of which height is safe: the existing output caps. Again bend the leads so that they reside in the valley, in the horizontal plane flat with those big caps. Make sure they don't stick out above that height.

Now comes the finicky part of connecting the leads of the bypass caps to the leads of the existing output caps. For that I just used some jumpers or clipped-off leads from stuff you soldered before. I leave it up to your best soldering skills. What I did was first apply some solder on the jumper as well as on the leads of the existing caps. Then I soldered the jumper to the base of the existing caps, not 100% right but in such a way that they at least stay put. I then soldered the jumper to the lead of the bypass cap, and finally got back to the base connection to fix that up.

When you're done, you can use something straight to check that the leads are no higher than the big black caps and you're good to go.



Remember that like other caps, these too need burn-in. Happy listening


----------



## PetFju

hmscott said:


> @PetFju - how have your component upgrades gone?  Have you had any additional changes?  How has the sound changed as the caps aged?
> https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16735640
> https://www.head-fi.org/threads/xduoo-amplifiers.682282/post-16735863


Sorry for the late reply, i have had a very busy schedule the last few months, and it'll stay that way until june unfortunately. Which also means i haven't had as much time as i'd like to listen to music. 
As far as the changes i haven't really heard any sort of "burn in" effects, even though i sort of expected it. I guess that means the changes have been subtle if any compared to the stock caps. I am gonna give the caps some more time before i swap them for the Jantzen caps, and at that point any changes should be apparent. At least when comparing Mundorf to Jantzen.
However, it seems like the stock caps are adequate from my hearing at least  But i will update more on this matter later. 

As far as the MT-603 goes i have to say that it haven't been all i wanted it to be. The TA-26 as a preamplifier still beats it handily as far as sound quality goes. But as a "tubeifier" it does its job. Nothing more, nothing less. I will however remove it from my current setup when i find the time to fiddle with it, as the best possible sonics i've heard through my setup is setting the TA-26 up as a pre for the Atrox V2. The sound of those two combined is actually very close to what i would imagine high end sounds like (without any "real" high end references in head-fi at this point). In many ways it would be a similar setup to the TA-20 as the tubes preamplify the class A Atrox amp, however the Atrox seems to scale well. And with the power output it has it just keeps everything so controlled, clear and immediate all at once, but with those tubey "edges".


----------



## Ufanco

Today switched up my system and instead of using the oriolus ba300s as the preamp i‘m using the ta20 as the preamp by running the lxr output with a 4.4 adapter into the oriolus that’s connected to headphone. Running it like the has created a ground loop humm. 
If I touch the ta20 or wires humm goes away. Not sure why that is so figured I would ask.


----------



## hmscott (Apr 15, 2022)

PetFju said:


> Sorry for the late reply, i have had a very busy schedule the last few months, and it'll stay that way until june unfortunately. Which also means i haven't had as much time as i'd like to listen to music.
> As far as the changes i haven't really heard any sort of "burn in" effects, even though i sort of expected it. I guess that means the changes have been subtle if any compared to the stock caps. I am gonna give the caps some more time before i swap them for the Jantzen caps, and at that point any changes should be apparent. At least when comparing Mundorf to Jantzen.
> However, it seems like the stock caps are adequate from my hearing at least  But i will update more on this matter later.
> 
> As far as the MT-603 goes i have to say that it haven't been all i wanted it to be. The TA-26 as a preamplifier still beats it handily as far as sound quality goes. But as a "tubeifier" it does its job. Nothing more, nothing less. I will however remove it from my current setup when i find the time to fiddle with it, as the best possible sonics i've heard through my setup is setting the TA-26 up as a pre for the Atrox V2. The sound of those two combined is actually very close to what i would imagine high end sounds like (without any "real" high end references in head-fi at this point). In many ways it would be a similar setup to the TA-20 as the tubes preamplify the class A Atrox amp, however the Atrox seems to scale well. And with the power output it has it just keeps everything so controlled, clear and immediate all at once, but with those tubey "edges".


Hey @PetFju - happy to see you are keeping busy 

Yup, music can be distracting, especially when it sounds sooo great!

I was looking at these Jantzen Audio 8.2uF 800V Z-Silver Capacitor as potential replacements - but I would need to do more research, as I suspect there are even "better" caps:

Jantzen Audio 8.2uF 800V Z-Silver Capacitor
https://www.parts-express.com/Jantzen-0674-8.2uF-800V-Z-Silver-Capacitor-027-786


Ufanco said:


> Today switched up my system and instead of using the oriolus ba300s as the preamp i‘m using the ta20 as the preamp by running the lxr output with a 4.4 adapter into the oriolus that’s connected to headphone. Running it like the has created a ground loop humm.
> If I touch the ta20 or wires humm goes away. Not sure why that is so figured I would ask.


I don't think the 4-pin XLR headphone output is supported as a device driver input - you are experiencing the hum due to a ground loop - try using the RCA Output from the TA-20 instead.

If you do want to try to make that work - IDK if that is possible;  Do you have another output of the Oriolus also still connected to an input on the TA-20 or another output/input connected to the Oriolus from other devices?

I'd try disconnecting all devices from the TA-20/Oriolus - if you haven't already done that - to reduce the chance of ground loops.

Also, swap the power inputs to both the Oriolus / TA-20 once they are only connected together; If they are plugged into the same power outlet/strip, try 2 different outlets, and if they are on different outlets try putting them both on the same one.

I wouldn't try "cheater plugs", that break the Ground Pin contact to the power outlet for both or either device... you could touch both at the same time and create a current path - and Zap!

Good luck with your testing.


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## Ufanco (Apr 15, 2022)

hmscott said:


> Hey @PetFju - happy to see you are keeping busy
> 
> Yup, music can be distracting, especially when it sounds sooo great!
> 
> ...


Yeah I just will have to continue to use the oriolus between the source and the ta20 it’s only has a 4.4 input and output and battery powered. Just thought might sound better using it after the ta20 since it’s the oriolus is a full tube amp. I thought the rca out was more of a bypass than a output and didn’t go thru the tube section of the ta20? Either way don’t think there’s a way to connect it to the rca output.
Plus didn’t hear much of a difference by switching them around. Of course had to touch the ta20 to remove the humm so really didn’t spend a lot time testing. More was curious on what was causing the humm and experimenting.


----------



## roderickvd (Apr 15, 2022)

hmscott said:


> I was looking at these Jantzen Audio 8.2uF 800V Z-Silver Capacitor as potential replacements - but I would need to do more research, as I suspect there are even "better" caps:
> 
> Jantzen Audio 8.2uF 800V Z-Silver Capacitor
> https://www.parts-express.com/Jantzen-0674-8.2uF-800V-Z-Silver-Capacitor-027-786


Do you intend that for the TA-20 or TA-26? They won't fit in the TA-20. I've looked at all Mundorf, Jantzen, Audyn and ClarityCap options, and none of them will fit except the most basic ones. And @PetFju confirmed my assumption that the stock ones probably already are in the same league.

As for the TA-26, I don't have it (yet - would be fun to own sometime) but I think you could replace those six red capacitors with something better. Could also be a s single big one. Do they have a capacitance printed on them though? Otherwise you would need to measure them and I don't know if you own such equipment?


hmscott said:


> I don't think the 4-pin XLR headphone output is supported as a device driver input - you are experiencing the hum due to a ground loop - try using the RCA Output from the TA-20 instead.
> 
> If you do want to try to make that work - IDK if that is possible;  Do you have another output of the Oriolus also still connected to an input on the TA-20 or another output/input connected to the Oriolus from other devices?
> 
> ...


Looking at that Oriolus, does it only run on batteries? Otherwise definitely use the same wall outlet.

How is the wire run, are they alongside other wires, particularly power wires, or are they coiled up?

Have you ever opened up the TA-20? It does seem like their is a failed earth connection.


----------



## roderickvd

Ufanco said:


> I thought the rca out was more of a bypass than a output and didn’t go thru the tube section of the ta20? Either way don’t think there’s a way to connect it to the rca output.


This is correct.


----------



## Ufanco

roderickvd said:


> This is correct.


Thanks my last thought is the distance btw the to units. The only 4.4 to 4.4 cables are I have are short so there only about 3 inch of space separating them.


----------



## hmscott (Apr 16, 2022)

roderickvd said:


> Have you ever opened up the TA-20? It does seem like their is a failed earth connection.


@Ufanco - the Green / Yellow Stripe ground wire is easily accessible under the bottom plate.  If you remove the plate screws and lift the bottom plate, wiggle that Green / Yellow Stripe wire and see if it is attached securely.  A few owners have reported that the screw is loose, and one said the lock-washer was missing, which over time will cause the nut to loosen.  A loose ground connection can be a contributing factor to audible noise.

Good call @roderickvd !


Ufanco said:


> Yeah I just will have to continue to use the oriolus between the source and the ta20 it’s only has a 4.4 input and output and battery powered. Just thought might sound better using it after the ta20 since it’s the oriolus is a full tube amp. I thought the rca out was more of a bypass than a output and didn’t go thru the tube section of the ta20? Either way don’t think there’s a way to connect it to the rca output.


Yes, the RCA output is a passthrough from the input, but I was thinking of functional use without the ground loop problem more than tube buffer effect.  Besides why would you need the TA-20 tube buffer effect in your setup if you have a full tube amp that can act as the tube buffer?  Perhaps I am missing your need for your set up.

The TA-26 does have an output from the tubes, it's RCA output would work if you need it.


Ufanco said:


> Plus didn’t hear much of a difference by switching them around. Of course had to touch the ta20 to remove the humm so really didn’t spend a lot time testing. More was curious on what was causing the humm and experimenting.


That's good, I go through a lot of that with new equipment, none are immune given the right (wrong?) circumstances.

Having fun is the real win 

I got rid of a lot of my noise problems by replacing my cables with interrupted shield cables - kind of a "directional" design.  The source side has the cable shield soldered/connected, allowing the length of the cable shield to absorb the RFI/EMI protecting the signal wires, and then at the destination end the shield is lifted or not soldered/connected so that the shield noise signals can't be passed on to the destination device.


Spoiler: For the hum you are hearing I would try a Worlds Best Cables RCA/XLR cable:



*1 Foot – Directional Quad High-Definition Audio Interconnect Cable Pair Custom Made by WORLDS BEST CABLES – Using Mogami 2534 Wire and Amphenol ACPR Die-Cast, Gold Plated RCA Connectors $31*
https://www.amazon.com/Foot-Directional-High-Definition-Interconnect-Connectors/dp/B01ALHTVMO

The cable/wire description is from Mogami:


The design description from WBC comes down to lifting the shield ground at the destination end.  That keeps the shield borne induced noise out of the TA-26:


The WBC RCA cables got rid of all the of the Topping A90 RCA noise except for the PC GPU noise borne by the USB power wires (iDefender+ got rid of that).  I also have a $100+ filtered power strip, but with that alone, before the WBC cables and iDefender+, the filtered power strip wasn't enough to get rid of all the noise.

During normal listening with the TA-26 Volume knob at the highest listenable setting, with or without music, I don't hear any hum.

I also use the XLR cables with lifted shield at destination design, sold per channel, buy two for a stereo pair:

1 Foot – Quad Balanced Microphone Cable Custom Made by WORLDS BEST CABLES – Using Mogami 2534 Wire and Neutrik NC3MXX-B Male & NC3FXX-B Female XLR Plugs.
https://www.amazon.com/gp/product/B00WU1BP10



It is good practice to solve such grounding / ground loop issues - even if you can avoid them by "not doing that", some day those skills will come in handy in a pinch situation.

Have fun 


Ufanco said:


> Thanks my last thought is the distance btw the to units. The only 4.4 to 4.4 cables are I have are short so there only about 3 inch of space separating them.


Shorter cables are better for noise reduction as long as the cases aren't touching.  In fact shorter is generally - I can't think of an exception right now - better for reducing cable induced noise.  The cables are little antennas that can pick up induced RFI/EMI, the lifted shield cables help, but shorter lengths also help.

You might be thinking of your own bodies effect when you bring your hand close to a tube or chassis and you hear an audible change.  Your body is a huge antenna picking up RF, if you touch a radio antenna you can improve/degrade the reception because of that.  You are also a grounding substitute - or an actual ground if you have bare feet standing in salty water, and anything close to ground in between.

When I set up a transmitting station I have to make sure a ground bar system is in place with long rods pounded into the ground - salted into their hole as they are pounded into the ground.  Yes, I stand on a ladder and pound steel rods into the ground 7'-10' are best, and yes the ground is soaked for days before-hand to make the soil soften by absorbing as much moisture as possible.  It often takes a couple of days in short stretches to pound it in.

Also you can use shorter 3' copper rods and tie them together, but you have to design the attachment such that all the rods share the load.

What I am saying is a good/great grounding system is important.  Your home may already have such a grounding system that you can tap into, either by running a thick wire to the already installed ground bar, or by simply connecting to the metal running the ground to your end of the home.

Alternatively there are also products to "bust the hum", some work with any setup some are unique to the makers products, ifi has released a few items to try:

_*iFi Groundhog+*_
*Does your system suffer from an irritating buzz or hum that decreases when you touch it? It’s missing an earth/ground. You need the Groundhog+.*
https://ifi-audio.com/products/groundhog/

_*iFi DC Blocker*_
*If you have a mechanical hum, deploy the DC Blocker.*
https://ifi-audio.com/products/dc-blocker/

_*iFi GND Defender
The optimum configuration for each system is one Ground/Earth for the whole system. If a system has multiple Grounds/Earths, then it often creates unwanted ground loops. These systems will then have an annoying low-frequency hum (emitted from the speakers).
Current solutions either jeopardize (i) both safety and EMI shielding (e.g. cheater plug), or (ii) EMI shielding. And most are single country (US) uses only.*_
*The GND Defender in the correct way, intelligently detects a ground loop and will cut the ground for that component.*
https://ifi-audio.com/products/gnd-defender/

Another Power/Ground related item I need and use is the:

_iFi iDefender+
Is your audio still taking a beating from buzz and hum?
iFi’s iDefender+ is for those battling with noisy audio due to unwanted ground loops in their audio chain._
https://ifi-audio.com/products/idefender-plus/

Topping has recently come out with the:

HS01 - USB 2.0 High Speed Audio Isolator, which accomplishes the same effect of blocking the noise borne across the USB ground/power wires:
https://www.tpdz.net/productinfo/733226.html

I have 2 DAC's connected to my PC, the D90 MQA and the FiiO M15, I use both frequently, I use both an HS01 and an iDefender+

After replacing my cables with the WBC shield lifted cables, replacing my USB DAC cable with a Jenving USB 2.0 cable all of my noise was gone, but when I gamed or ran CUDA based software the GPU "song" would rise up - coming up the power/ground wires of the USB cable - the iDefender+ detects that signal and nullifies it, that was the last change I need to make to remove all the noise between my A90 and D90 MQA devices.

Another way to remove ground loops is to detach from the power line and use a battery driven Pure Sinewave AC source.  They are out of stock now, but this one has enough battery storage to run my D90/A90 for 10+ hours.  RavPower say they will restock, but it has been "Sold Out" for weeks:

Power Station 252.7Wh Power House
Model: RP-PB187BSPF
https://www.ravpower.com/products/rp-pb187-portable-power-station

It is important to find an AC power source that has a true/pure sine wave for running audio devices, there are many out there that are not - for running power tools. 

So there are lots of things to do to work out the ground loop / grounding problem and similarly the RFI/EMI noise, I've only listed a few.

Have fun


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## hmscott (Apr 16, 2022)

Please delete.


----------



## roderickvd

If you don't intend to roll any of the components, then I don't understand your post regarding your investigations on the Jantzen Audio 8.2uF 800V Z-Silver Capacitor?

I don't think the audio caps in the power section are overkill, in the meaning of "overkill" as "too much of something good". Putting audio signal caps there is the wrong application for those caps and does not bring any particularly goodness to the power supply function. The new Panasonic power supply caps I got in the mail today, now those may be overkill because other, cheaper power supply caps might have been good enough.

I agree on your assessment about "stock on hand" as well as marketing material, which in fact xDuoo does tout on their pictures. As for paying attention, it seems to me that attention was paid to make it marketable and work well enough, not to make it the best technical selection even though the Panasonic FR and Nichicon FW cost about the same.

Don't get me wrong, I do think that xDuoo paid more attention than average and I compliment them on that. But even then designers work within the boundaries of what is commercially interesting to the company, with most always room to do better technically in some respect.


----------



## hmscott (Apr 16, 2022)

PetFju said:


> ...I am gonna give the caps some more time before i swap them for the Jantzen caps, and at that point any changes should be apparent. At least when comparing Mundorf to Jantzen.
> However, it seems like the stock caps are adequate from my hearing at least  But i will update more on this matter later.





roderickvd said:


> If you don't intend to roll any of the components, then I don't understand your post regarding your investigations on the Jantzen Audio 8.2uF 800V Z-Silver Capacitor?


@PetFju 's mention of Jantzen Caps as a replacement for the caps he installed spurred my search to see what he was talking about, and I posted the specific part info I found to confirm that is what he was talking about, and to continue the conversation.

Just because I'm not going first into that experimental void, doesn't mean I am not interested in helping the pioneering efforts along in some way, hoping that I can reap the benefits of success later myself, maybe.

I'm happy with how the TA-20 sounds with E80CC/E180CC tubes, and in comparison to the best tube combinations I've found so far for the TA-26 - side by side the TA-20 is keeping up nicely.

Yes, I don't want to mess around inside either the TA-20 or the TA-26 and lose that Xduoo finely tuned edge of audio performance I am enjoying right now, but I will participate in the discussion about potential parts rolling, the same as I have been discussing tube rolling.  I don't buy all the tubes discussed either, but I am interested in and will research the options available.


----------



## Ufanco

Thank you both for the help. I checked ground on the ta20 and seems fine decided just to keep using the Oriolus ba300 as a preamp. I know it sound like a weird setup by I like the way it sounds and in the end that’s the most important thing. 
​


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## roderickvd (Apr 16, 2022)

Little update on recapping the power supply: the Panasonic FR does *not* work -- do not put them in. I don't own a scope but I think the SMPS becomes unstable because the ESR of the FR is too low. There is erratic switching of the relays and the control panel doesn't work well at all. Not good!

I ordered some other caps with the same ESR as the stock Nichicon FW's: the 4700μF 25V Nichicon PW and 35V Nichicon KW. The former is made for SMPS duties, the latter is the higher audio quality version of the FW. I will report back once I have received them and got them in. Larger capacitance would be nice, though not strictly necessary for SMPS duties.

If the SMPS doesn't like larger capacitance either, it might fail to start up. For that case I also put some Rubycon ZLJ's 3300μF in my basket.


----------



## Laines (Apr 17, 2022)

Hello,
Im using the MT-602 pre-outs for my powered desk speakers. When I turn on my desk speakers *before *the MT-602 I get a really loud "pop" when the MT-602 turns on.  In the documentation from the MT-602 they mentioned a "mute circuit" which should prevent exactly what's happening.

Do I have a faulty unit, any ideas?


----------



## roderickvd (Apr 17, 2022)

Amidst these SMPS / power supply capacitor compatibility woes, I got another idea: why not cut the SMPS out of the equation and draw 12V from an external, low noise, linear power supply?  I'll be in touch... looking for a part to replace the current AC power socket + button snap-in with a DC power socket.

Edit: couldn't find one so I'll ask a colleague to 3D print one, with a through hole for a DC jack.


----------



## hmscott

Laines said:


> Hello,
> Im using the MT-602 pre-outs for my powered desk speakers. When I turn on my desk speakers *before *the MT-602 I get a really loud "pop" when the MT-602 turns on.  In the documentation from the MT-602 they mentioned a "mute circuit" which should prevent exactly what's happening.
> 
> Do I have a faulty unit, any ideas?


If you are curious you could ask service@xduoo.com

I'd assumed the mute circuit was for the headphones output only - do you hear a thump in your headphones when you turn on the MT-602 with headphones connected?

For now I'd simply follow the age old wisdom and turn on your AMP after your source has gone through it's power on cycle and everything is working ok.  You never want to turn on your final amplifier 1st - to avoid thumps and squawks in the speakers.  Even if the amplifier is in the speakers


----------



## hmscott (Apr 18, 2022)

roderickvd said:


> Amidst these SMPS / power supply capacitor compatibility woes, I got another idea: why not cut the SMPS out of the equation and draw 12V from an external, low noise, linear power supply?  I'll be in touch... looking for a part to replace the current AC power socket + button snap-in with a DC power socket.
> 
> Edit: couldn't find one so I'll ask a colleague to 3D print one, with a through hole for a DC jack.


I am pretty sure the TA-20 / TA-26 use AC - 6.3VAC powered - not DC powered - tube heater power...and there are other functional reasons for the AC power to be connected to the transformer windings, besides powering the SMPS.

I don't think you can replace the TA-20 AC power with DC without a bunch of additional modifications.


----------



## roderickvd

That is an excellent point. You are right.


----------



## Ufanco

Went back and listened to some of the 12ua7 tubes and it made me realize how mush better the 12bh7 sound in the ta20. Even my past favorites like the pinnacle 13d5a and Amperex ecc82 are not in the same league. If you can afford even the inexpensive cbs12bh7 I would highly recommend it.  
Currently have my eye on a blue tip set of sylvania 12bh7 but already have more tubes than I need. I really need to sell/give some away.


----------



## ProAcTivo

Just some tube rolling. I switch the Tung-Sol 6SN7GTB new production Russian made for a Tung-Sol 6SN7GTB Tall Boy D getter made in USA, not NOS but almost as new. They are a little different in sound. The older Tung-Sol is more refined. More focus overall, vocals more defined a bit forward. Bass less impacfull but faster. I think is cleaner sounding overall. For now im liking it a lot with the RCA 6AS7G. Both are smooth but the newer 6SN7GTB is less detailed, perhaps more easy listening with any kind if music, but i do miss the extra detail that the USA made 6SN7GTB gives. So for now RCA 6AS7G + Tung-Sol 6SN7GTB (made in USA) is my best combo for the TA-26.


----------



## jonathan c

ProAcTivo said:


> Just *some *tube rolling. I switch the Tung-Sol 6SN7GTB new production Russian made for a Tung-Sol 6SN7GTB Tall Boy D getter made in USA, not NOS but almost as new. They are a little different in sound. The older Tung-Sol is more refined. More focus overall, vocals more defined a bit forward. Bass less impacfull but faster. I think is cleaner sounding overall. For now im liking it a lot with the RCA 6AS7G. Both are smooth but the newer 6SN7GTB is less detailed, perhaps more easy listening with any kind if music, but i do miss the extra detail that the USA made 6SN7GTB gives. So for now RCA 6AS7G + Tung-Sol 6SN7GTB (made in USA) is my best combo for the TA-26.


… ‘some’ will lead to ‘more’!… have no fear, it’s fun 🤪🤣. The TA-26 is a _great _way to be involved with tube amplifiers - OTL, no less !


----------



## ProAcTivo

jonathan c said:


> … ‘some’ will lead to ‘more’!… have no fear, it’s fun 🤪🤣. The TA-26 is a _great _way to be involved with tube amplifiers - OTL, no less !


Yes i know. What have i done to myself 🤣


----------



## Ufanco

jonathan c said:


> … ‘some’ will lead to ‘more’!… have no fear, it’s fun 🤪🤣. The TA-26 is a _great _way to be involved with tube amplifiers - OTL, no less !


I went a bit overboard with tube rolling and bought a bunch of 12au7 before finding the 12bh7 sound better in the ta20. Oh well it was fun to experiment and most of the 12au7 hopefully will find new homes. 
Just checking in to see if anyone has made any progress on 3d risers for the ta20?


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## Ufanco (May 3, 2022)

Recently I picked up some 12bh7 CBS 1950’s white tipped tubes. Sadly there was a loud hiss so figured they where bad tubes. They where inexpensive so no big deal.
I was going to just toss them but decided to let the burn in overnight. The next day they sounded much better and was just a slight hiss that was only noticed when nothing was playing. After a week of use the hiss is almost completely gone. These are now one of the best sounding tubes in my collection
This was unexpected and just wondering if anyone had thoughts on why the hiss disappeared ?


----------



## jonathan c

Ufanco said:


> Recently I picked up some 12bh7 CBS 1950’s white tipped tubes. Sadly there was a loud hiss so figured they where bad tubes. They where inexpensive so no big deal.
> I was going to just toss them but decided to let the burn in overnight. The next day they sounded much better and was just a slight hiss that was only noticed when nothing was playing. After a week of use the hiss is almost completely gone. These are now one of the best sounding tubes in my collection
> This was unexpected and just wondering if anyone had thoughts on why the hiss disappeared ?


The tubes are about seventy years old. It seems plausible that, after being idle for a substantial time, break-in and attainment of optimal running temperature are necessary for the tubes to ‘come on song’.


----------



## Ufanco

jonathan c said:


> The tubes are about seventy years old. It seems plausible that, after being idle for a substantial time, break-in and attainment of optimal running temperature are necessary for the tubes to ‘come on song’.


Humm that makes sense I’m listening right now and the hiss is almost completely gone. Have to really Concentrate to hear anything now. I’m also using the mest mkii and the resistance is 12.3 so there really sensitive.


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## hmscott (May 5, 2022)

Ufanco said:


> Recently I picked up some 12bh7 CBS 1950’s white tipped tubes. Sadly there was a loud hiss so figured they where bad tubes. They where inexpensive so no big deal.
> I was going to just toss them but decided to let the burn in overnight. The next day they sounded much better and was just a slight hiss that was only noticed when nothing was playing. After a week of use the hiss is almost completely gone. These are now one of the best sounding tubes in my collection
> This was unexpected and just wondering if anyone had thoughts on why the hiss disappeared ?





jonathan c said:


> The tubes are about seventy years old. It seems plausible that, after being idle for a substantial time, break-in and attainment of optimal running temperature are necessary for the tubes to ‘come on song’.





Ufanco said:


> Humm that makes sense I’m listening right now and the hiss is almost completely gone. Have to really Concentrate to hear anything now. I’m also using the mest mkii and the resistance is 12.3 so there really sensitive.


I sure wish that trick worked with the tubes I bought that "HISS" 

Starting with my first pair of "Used" tubes, listed on eBay with an 85% "NOS" measurement of  "New", I immediately heard HISS when listening with IEM's.  But, that "IEM test" was done after listening for a couple of weeks with over-the-head headphones before I remembered to test with IEM's:

"RCA 12au7 Black plate matched pair top tilted getter 1955", purchased on Feb 23, 2021:


Sorry for the poor image, it is an eBay thumbnail from my purchase history.  Completed eBay listings after a certain time period are expunged by eBay.

I had been rocking out with my TA-20 since I got it in December 2020 with "new re-issue" tubes, and after a couple of weeks of enjoying these  12au7 Black plate tubes with my over-the-head headphones - mostly Sennheiser HD598cs's back then - I decided to check out how my IEM's sounded, and "BAM!" I was hit by a "wall of HISS!".

And, it wasn't just a little HISS, it was an overwhelmingly shocking level of HISS, so much HISS I couldn't believe it was only heard my IEM's.  How could that be? When I switched back to the Sennheiser HD598cs "over-the-head" headphones the RCA tubes were as quiet as can be, not even a little background noise.

It occured to me that since those "NOS" 85% measuring RCA tubes HISS'd so badly, perhaps "as new" measuring tubes would be my best shot at getting tubes I could listen with my IEM's too, without a "wall of HISS".

The RCA pair didn't "HISS any Less" over the next couple of weeks I listened to them either, but since they sounded fine with over-the-head headphones I kept using them until my first "new" "100%+/100%+" tubes arrived.  BTW, I learned to never purchase from "No Returns Accepted" sellers on eBay, as this seller wouldn't accept my Return Request, even though in eBay Messages he apologized and assured me he would allow me to return them.

_With my next tube purchase I was intent on finding a great set of "100%/100%" measuring tubes.

I asked each seller for only 100%/100% measuring tubes, as I heard a "Wall of HISS" in "NOS" 85% used tubes, and a couple of the sellers informed me, that in their experience, HISS in Used tubes indicates the tubes are "Used up".

Earlier there were sellers that admitted that with"NOS" tubes the measurements can be as low as 85% and they are still considered as "NOS".  What a revelation, right? 

That is why I started asking sellers for tube measurements for tubes listed only as "NOS".  I've since learned that few sellers will provide measurements if the measurements aren't in the original listing, I wonder why?_**

After I heard that shocking "Wall of HISS" I decided I needed to figure out if 100%/100% measuring tubes would still HISS - or I'd be stuck listening with only "new issue" tubes with my IEM's, fortunately these 100%/100% measuring tubes didn't HISS at all:

"matched quad ECC82 / 12AU7 from philips miniwatt"




Tracking down 100%+/100%+ measuring tubes has worked great ever since, until I bought a "New" Quad of "130% / 130%" tubes off of eBay that HISS'd in my IEMs, also discovered after listening happily for a couple of weeks with over-the-head headphones.

I have been pretty focused on listening with over-the-head headphones for a while - buying tubes instead of new IEM's - so I didn't test with IEMs until halfway through that "130%/130%" Quad's 30 days acceptance.

I was surprised to find those "130%/130%" measuring tubes had a "wall of HISS" similar to the "NOS" 85% *"*_Used up"_ RCA tubes...so as I packed them up for return, I couldn't help but notice that the "New" original boxes the tubes were shipped to me in had "handwritten" notes on them..."handwritten notes" as to which "AMP channel/side" each tube came from lightly written in pen on each tube box...of the "New" assumingly "unused" tubes...

In my experience, listening with over-the-head headphones for 2 weeks+ before listening with IEM's hasn't helped any of my tubes that "HISS" stop hissing, but how would I really know?!, since I always listened for a couple of weeks with my "over-the-head" headphones before testing with my IEM's!


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## roderickvd (May 5, 2022)

This is on the TA-20, right? It hisses on my Sylvania 6189W’s too which are known to exhibit low noise. But the TA-20 has been measured on ASR with lots of noise, particularly on the single-ended output with low impedance loads and low power levels. I don’t think it’s a good amp for IEM’s.


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## hmscott (May 5, 2022)

roderickvd said:


> This is on the TA-20, right? It hisses on my Sylvania 6189W’s too which are known to exhibit low noise. But the TA-20 has been measured on ASR with lots of noise, particularly on the single-ended output with low impedance loads and low power levels. I don’t think it’s a good amp for IEM’s.


The TA-20 is perfect for listening to IEM's, as all of my non-HISSy tubes have an extremely dark background on the TA-20 in my sensitive IEMs, and there is no humanly audible noise from the TA-20 with my sensitive IEM's, none, at least with this human listening.

ASR's measurement levels of "lot's of noise" in "minus" dBm down so far that the human ear wouldn't be able to hear that noise.  It is only "a lot of noise" in relative terms in comparison on graphs, not possible to be detected by human ears.

Yup, all of that discovery and learning was with my TA-20.

The TA-20 stock tubes didn't have any noise nor any HISS in my IEMs, and the "re-issue" 12AU7's PSVANE, Telefunken, Golden Lion tubes didn't have any noise in my IEM's, nor any HISS either.  "New" tubes, whether actually new or "Old" tubes that measure as "New" won't have any noise in the TA-20, at least to my ears.

For my TA-26 I've acquired only 100%/100% measuring 6SN7 / 6AS7G and variant tubes for my TA-26, and none of those have HISS or noise in my sensitive IEM's either.

If your Sylvania 6189W's are noisy, in my experience it is not noise generated by the TA-20.

The stock 12AU7 tubes that came with the TA-20 have no noise nor HISS, please go back and check.

You can find "New" unused "old" tubes that will have absolutely no noise in your TA-20.  It takes time and patience to learn all of this through experience listening with a lot of different tubes.  That is why I take the time to share my experiences so you don't need to become overly concerned early on with "noisy" or "HISSy" tubes.

You can experience the same "no noise" and "no HISS" with "New" measuring "Old" tubes in your TA-20. 

There *are* great "noise-free" and "hiss-free" tubes from the '40's and '50's, and 60's out there!


----------



## roderickvd

Good to know there are tubes that work well with IEMs on the TA-20 then. Of course the measurements on ASR were with the stock tubes so they are a bit confounded, mixing up the tubes with the TA-20 itself. 

I don’t believe the measurements are below human hearing threshold. IIRC they measure THD+N both as a percentage as well as dB. At -40 dB it shouldn’t be “a wall” of hiss, but certainly audible (most volume controls have a working range between 0 and -60 dB).


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## hmscott (May 5, 2022)

roderickvd said:


> Good to know there are tubes that work well with IEMs on the TA-20 then. Of course the measurements on ASR were with the stock tubes so they are a bit confounded, mixing up the tubes with the TA-20 itself.
> 
> I don’t believe the measurements are below human hearing threshold. IIRC they measure THD+N both as a percentage as well as dB. At -40 dB it shouldn’t be “a wall” of hiss, but certainly audible (most volume controls have a working range between 0 and -60 dB).


Distortion is not background noise.  There needs to be a signal behind the THD+N measurement - with no signal at all then there would be no way to measure distortion / THD+N.

Background noise is when there is no signal, and on the TA-20 with the volume up all the way I hear literally no sound coming out of the IEM's or "over-the-ear" headphones.  That is what I mean by "no noise".

Do you hear any noise at all coming out of the TA-20 with the stock tubes using the same IEMs you heard the background noise, or "low level HISS", with the Sylvania 6189W's?

Please check, no rush, please let the stock tubes warm up for an hour or two before testing, and I will wait here patiently.


----------



## roderickvd

Agreed, THD+N is another debatable measurement — which is it, THD or N?

I hear noise with no signal applied with my Sylvanias.

As for the stock tubes, you’ll have to wait for more than two hours I’m afraid  first because I’m on holiday, second because I currently have a non-working amp as I’m trying out different PSU caps.

I will post a write-up when I have completed my tinkering. As a teaser of my preliminary findings, I was all wrong about my earlier assumptions on an SMPS being within the transformer cage (it’s on the PCB, after the caps) and also the TA-20 seems to be *very* picky about the ESR of the caps to the point that it won’t work unless exactly matched.


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## hmscott (May 6, 2022)

roderickvd said:


> Agreed, THD+N is another debatable measurement — which is it, THD or N?
> 
> I hear noise with no signal applied with my Sylvanias.


It "sounds-like" your Sylvania 6189W's have "internally" generated noise - a common occurrence as the cathode material burns off and expels material, depositing those hot materials onto the grid wires and other internal surfaces.


roderickvd said:


> As for the stock tubes, you’ll have to wait for more than two hours I’m afraid  first because I’m on holiday, second because I currently have a non-working amp as I’m trying out different PSU caps.


And, that is why I haven't torn my TA-20 apart yet either.  I realized I'd need to buy another TA-20 to make sure I could keep one running. 

Happy Holiday!


roderickvd said:


> I will post a write-up when I have completed my tinkering. As a teaser of my preliminary findings, I was all wrong about my earlier assumptions on an SMPS being within the transformer cage (it’s on the PCB, after the caps) and also the TA-20 seems to be *very* picky about the ESR of the caps to the point that it won’t work unless exactly matched.


Cool, I look forward to your findings. 


Spoiler: Star Trek!!



BTW, "I will wait here patiently", if you didn't look, is the new Star Trek: Strange New Worlds Series 1 Episode 1:
https://www.paramountplus.com/shows/star-trek-strange-new-worlds/

It has it's flaws (ok, a lot of technical ones, sigh), but it was colorful and exiting to watch, and it is nice to see they are keeping the Star Trek Universe alive!

There are a number of new shows on paramountplus.com, which is why I restarted my subscription 

Picard got a new 2nd season!
https://www.paramountplus.com/shows/star-trek-picard/

Season 3 trailer for Star Trek: Lower Decks!
https://www.paramountplus.com/shows/star-trek-lower-decks/

And, Star Trek Prodigy is getting a Season 2, I hope in 2022:
https://www.paramountplus.com/shows/star-trek-prodigy/
Hey, do you get Paramount Plus in the Netherlands yet?   I've heard VPN's are wonderful... 

Paramount+ Launching In UK And Ireland In June, Including ‘Star Trek: Strange New Worlds’
https://trekmovie.com/2022/05/03/pa...-june-including-star-trek-strange-new-worlds/


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## Ufanco

A lot of interesting thoughts on tubes and hiss. Are you guys using balanced or single ended in setup? I use balanced for mine and tried a bunch tubes and only found hiss with 2 pairs. What is the independence of the iem you guys using?
I also wonder if other things like connection cables and source would add to hiss. 
After testing tons of tubes the colored tipped tubes are all in the top 5 for sound. Decided that if I ever buy any more tubes will be these special tested tubes and 12bh7 made in the 1950’s. 
Kinda surprised on @hmscott issue with lower measurements effecting hiss. I bought a cheap collection of mid level tubes in the 70-85 range and don’t recall hearing hiss with them. I though that tubes continue to sound better the more time of usage. Guess considering that was based on someone else experience. Currently lot tube info is based on forum etc, instead of being tested In a controlled setting. 
 Most of us don’t have tube tester so need to relay on a honest seller for nos tubes. I only have one pair of newer tubes and there about middle ground in sound, so not sure I want spend money on new tubes. I also find it fun to search ebay and other site in search of deals and the colored tip tubes.


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## hmscott (May 5, 2022)

@Ufanco - I'm happy to hear you have found your end game tubes, that is always a tough decision, but I think you chose well 

Do you use IEM's?, or only Over-The-Ear (regular) Dynamic Headphones?  What headphones/IEM's were you using when you hear HISS in those 2 pairs?

Regular dynamic headphones don't seem to show the HISS like IEM's with BA transducers (speakers).   The only person so far that mentioned that they can hear HISS from tubes in their headphones said they listened with Focal Clear headphones.  So I can imagine other Focal headphone models might also be sensitive and extended enough in the treble range to output audibly the HISS, but IDK for sure because I've never heard Focal headphones.

Even cheap KZ IEMs can show the HISS, I think I was listening to KZ ASX the first time I heard the HISS, but that one is large with 20BA's, and it is a bit expensive, around $88 right now. Recently I heard the HISS in the KZ x Crinacle CRN (Zex Pro retune), and I just received the KZ EDA set, but I don't have any tubes easily handy that HISS to try them. I used balanced when I first heard the HISS, but it comes through on single-ended too, it doesn't matter which output is used.

And, it is true we need to rely on sellers to be accurate and honest, and so far I think I've found a bunch of good ones, and a few great sellers, who I've mentioned several times before.  Unfortunately all of the sellers are spotty in what they have in stock.  A great seller can sell out and then need to go offline for a while so they can restock the shelves.  That is the case right now for the ones I am thinking of, but the Ukraine guys are doing great too. It takes time to learn what to ask and why, and to learn your own preferences and limits.

I don't think you need to worry about anything if you only have a couple of sets that HISS, as I have the same


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## Silver Wolf (May 5, 2022)

Just scored a couple more NOS tubes, matched pair 'n spare late 1940's 12au7 (South Australia ) Mullard's, matched pair Philips Miniwatt 12bh7a and a Philips Miniwatt  5U4 rectifier. Happy days


----------



## Ufanco

hmscott said:


> @Ufanco - I'm happy to hear you have found your end game tubes, that is always a tough decision, but I think you chose well
> 
> Do you use IEM's?, or only Over-The-Ear (regular) Dynamic Headphones?  What headphones/IEM's were you using when you hear HISS in those 2 pairs?
> 
> ...


Using Mest mkii when I hear the hiss. There rather sensitive at 12.3. The one tubes that had a hiss has almost gone away, its now only noticeable if you really Concentrate on the sound. Since it sounds the best I’m hoping it keeps working. The other set is a Westinghouse 12au7 that ended up free so haven’t tried letting them burn in.

This weekend might try my phonak 232 iem there independence is 47 have a feeling I won’t hear the hiss with them.

Speaking of sellers I bought a lot of tubes for 3 pairs of Westinghouse Carbon plate tubes. Since I didn’t need the rest the tubes I ask seller just to send these 3 pairs.  Well instead of sending the 3 pairs I wanted he sent 5 pairs of the conn/Westinghouse 12au7. Guess he didn’t want to break up the lot and and said he thought they where the same thing. 
Kinda was Aggravated since we had chatted back and forth before purchasing this lot and I made it clear I was only buying the for the Westinghouse carbon plates. Anyway it ended up with him refunding me for them. He then didn’t want pay shipping back so he said just keep them.
The conn/Westinghouse 12au7 sound wise are really good but I have way more than I need. I already had this tube type in collection. That’s why I offered them on here earlier.
Still have a couple pairs left there free, just asking to cover the shipping cost.


Silver Wolf said:


> Just scored a couple more NOS tubes, matched pair 'n spare late 1940's 12au7 (South Australia ) Mullard's, matched pair Philips Miniwatt 12bh7a and a Philips Miniwatt  5U4 rectifier. Happy days


Can’t wait to hear your impressions on these tubes. I hope you find the 12bh7a improvements as special as I have. Haven’t see the Phillips miniwatt on eBay. The regular 12au7 Philips miniwatts are suppose to sound excellent so the 12BH7a could too.  I have one last set of RCA 12bh7 to test they where order before I got the others. Hopefully there not lost and arrive soon. I think thou I found my endgame with tubes.


----------



## ProAcTivo

Hi all.
Well, lately im having some hum sound coming from my TA-26 to my Sens HD600. Mostly on the left channel. The TA-26 alone always made some hum when on, but now the hum is also coming ou the headphones.. any thoughts?


----------



## hmscott

ProAcTivo said:


> Hi all.
> Well, lately im having some hum sound coming from my TA-26 to my Sens HD600. Mostly on the left channel. The TA-26 alone always made some hum when on, but now the hum is also coming ou the headphones.. any thoughts?


The TA-26 is making the mechanical humming sound?  You have some DC component on the AC line, try a DC Blocker in front of the TA-26 AC line to block that DC.  It could also be a mismatch of the locale AC and the TA-26 build.  What is your locale AC volts/hz?  What is the TA-26 say on the back/label/model info you bought?


----------



## CJG888

I would check and clean all connections (especially tube pins). Do you have a spare set of tubes so that you can eliminate a bad tube?

Other potential causes could be grounding issues (something which always seems to plague my systems) or a capacitor which is starting to fail…


----------



## ProAcTivo

hmscott said:


> The TA-26 is making the mechanical humming sound?  You have some DC component on the AC line, try a DC Blocker in front of the TA-26 AC line to block that DC.  It could also be a mismatch of the locale AC and the TA-26 build.  What is your locale AC volts/hz?  What is the TA-26 say on the back/label/model info you bought?


Not shure what a DC blocker is..but i will look into it. About the AC volts is all good..220V. I left the amp turned on all morning without tubes. Then i cleaned all the tube pins, and now i have very residual hum..not like before. Lets hope it still like this. If not i will report back.


----------



## ProAcTivo

CJG888 said:


> I would check and clean all connections (especially tube pins). Do you have a spare set of tubes so that you can eliminate a bad tube?
> 
> Other potential causes could be grounding issues (something which always seems to plague my systems) or a capacitor which is starting to fail…


Thank you. I did that. I cleaned all pins and now i have very minimal hum.. lets see. Thank you 😉


----------



## ColSaulTigh

DC blocker: https://avahifi.com/collections/used-demo-and-quick-ship/products/humdinger-dc-line-blocker


----------



## ProAcTivo

ColSaulTigh said:


> DC blocker: https://avahifi.com/collections/used-demo-and-quick-ship/products/humdinger-dc-line-blocker


Thank you. Well i guess the DC Blcker is not for me. It says it will not remove the hum coming out of speakers.. thats my case..its coming out of the headphones. The amp itself makes a little  it of noise when turned on (just a bit) but the hum is coming from the headphones(left channel mostly).


----------



## ColSaulTigh (May 13, 2022)

ProAcTivo said:


> Thank you. Well i guess the DC Blcker is not for me. It says it will not remove the hum coming out of speakers.. thats my case..its coming out of the headphones. The amp itself makes a little  it of noise when turned on (just a bit) but the hum is coming from the headphones(left channel mostly).


Disconnect everything from the amp and see if it goes away.  If it still hums, unplug it and move it to the other side of the house and see if the hum remains.  If so, it's more likely a tube causing it.  If it goes away, you've got an impedance mismatch somewhere.  Start adding components one at a time until you find it.


----------



## ProAcTivo

ColSaulTigh said:


> Disconnect everything from the shop and see if it goes away.  If it still hums, unplug it and move it to the other side of the house and see if the hum remains.  If so, it's more likely a tube causing it.  If it goes away, you've got an impedance mismatch somewhere.  Start adding components one at a time until you find it.


Ok. Will do that. I think is the Tung-Sol 6SN7GTB (Old made in USA). When i had the Tung-Sol 6SN7GTB new (Russia) i dont recall having the hum. For now is quiter but if the hum comes back i will try this.


----------



## Ufanco

ProAcTivo said:


> Ok. Will do that. I think is the Tung-Sol 6SN7GTB (Old made in USA). When i had the Tung-Sol 6SN7GTB new (Russia) i dont recall having the hum. For now is quiter but if the hum comes back i will try this.



Yes it’s really sounds like the tube is the issue. If you touch the tube or slightly move it we’ll it playing is sometimes is a dead giveaway that the tubes the issue.


----------



## CJG888

I have a NOS 1962 Valvo E88CC which sounds divine but is basically a microphone!

Provenance is no guarantee of reliability…

Random failures are always possible. Even in the best tubes.


----------



## hmscott (Jun 23, 2022)

ColSaulTigh said:


> DC blocker: https://avahifi.com/collections/used-demo-and-quick-ship/products/humdinger-dc-line-blocker





ProAcTivo said:


> Ok. Will do that. I think is the Tung-Sol 6SN7GTB (Old made in USA). When i had the Tung-Sol 6SN7GTB new (Russia) i dont recall having the hum. For now is quiter but if the hum comes back i will try this.





Ufanco said:


> Yes it’s really sounds like the tube is the issue. If you touch the tube or slightly move it we’ll it playing is sometimes is a dead giveaway that the tubes the issue.


Yup, clean pins and solid placement can make a big difference.  I recently acquired 3 FAA-6080WA's and they were tough for me to seat properly and the first couple I seated were lifted on one side and I not only got hum I got a "pop"/arc? when I first powered up the TA-26, so for those I make sure I am standing directly over the socket so I can get them fully seated with no air gaps between the tube base and the socket top. 

The Dark Voice 336E which is similar to the TA-26 is known to hum with new 6SN7's, and they recommend leaving the DV336E on overnight with only the 6SN7 plugged in and the 6AS7G pulled out, sometimes it takes 2 or 3 days of running like that for the hum to stop.  AFAIK the TA-26 doesn't have that quirk.

There have been a couple of owners in European countries with different power than their TA-26 is wired to accept and they were getting mechanial hum - the TA-26 is humming even without the tubes - and for those situations an RMA back to Xduoo allows parts swap to match their locale power.

Then there are the situations where there are DC ground loops and other problems with the DC power mixing with the AC, and iFi has a couple of new and older solutions for those problems, I'll link them here for future reference:

iFi DC Blocker
https://ifi-audio.com/products/dc-blocker/ <= more compact solution if you need it, they describe symptoms that can be solved with a DC blocker:

iFi GND Defender
https://ifi-audio.com/products/gnd-defender/  <= The *GND Defender *in the correct way, intelligently detects a ground loop and will cut the ground for that component.

My "hum / Buzz / Whistle" problem was EMI/RFI noise induced into the 5V powerline Ground of the USB connection from my PC (GPU mostly) to my Topping D90 DAC, so my solution was the iFi* iDefender+* is for those battling with noisy audio due to unwanted ground loops in their audio chain:

iFi iDefender+
https://ifi-audio.com/products/idefender-plus/

Topping has recently come out with another USB ground loop solution, which I use to connect my FiiO M15:

HS01 USB 2.0 High Speed Audio Isolator
https://www.tpdz.net/productinfo/733226.html

Another general ground loop solution:

Groundhog+ - Does your system suffer from an irritating buzz or hum that decreases when you touch it?  It’s missing an earth/ground. You need the Groundhog+.
https://ifi-audio.com/products/groundhog/
Lots of ways to pin point and solve these problems, and we all eventually come upon some them at some point in our lives


----------



## ProAcTivo (May 13, 2022)

Well, before i try everything you guys pointed out i did some experiments. I switched all the tubes to indetify the bad one. Turns out the problem occurs with all of them, even with the Russian made Tung-Sol 6SN7GTB. So, all have the same behaviour. No hum for the first 5 minutes but then the hum shows up. So i dont think is the tubes. I hear no hum for some time but after a while i can hear it clearly on the left driver in my Hd600... will try in a diferent room.


----------



## ProAcTivo

A question for the TA-26 owners. When you switch on the amp, theres no noise at all while is on? Mine emits a little buzz when on. Is not very loud but is clearly audible. Thank you


----------



## Ufanco

ProAcTivo said:


> Well, before i try everything you guys pointed out i did some experiments. I switched all the tubes to indetify the bad one. Turns out the problem occurs with all of them, even with the Russian made Tung-Sol 6SN7GTB. So, all have the same behaviour. No hum for the first 5 minutes but then the hum shows up. So i dont think is the tubes. I hear no hum for some time but after a while i can hear it clearly on the left driver in my Hd600... will try in a diferent room.


Darn was hoping just a tube issue that’s much easier to fix. There some suggestion posted above I would try them. Might be something on the same power line so differently try it on another outlet. Does hiss change if you touch unit well playing?

Here is a link with sound files of ground loop vs other issue. Cable, other equipment, heck even fluorescent light on same circuit. Kinda odd it starts after unit warms up. Hopefully other would add addition thoughts.

https://www.psaudio.com/ps-how/how-to-find-and-fix-hum/


----------



## ProAcTivo

Yes. When i touch the amp the hum reduce a little bit but not completly. I dont want to start buying things to try to remove the issue. I sent an email to Xduoo. Wil wait for the reply and then i will look into the issue again.

For now, i have to say that this amp produces a wonderful sound with my HD600s. Dispite this noise issues, the amp is absolutly fantastic with the senns. To be honest i was a bit desapointed with the HD600. I EQued them and was able to keep them for some time as the sound was more to my liking. But never totaly satisfied and lost in the music. The TA-26 was a last shot. And it was the right one. Beautiful sound. All kinds of music sound amazing to me. 

I have two questions for all TA-26 owners:
-What is the DAC you guys are using with this amp and why do you think it makes a great combo?
-What headphones you recommend with this amp, besides the HD600/650?

Thank you all.


----------



## muchacho

ProAcTivo said:


> Yes. When i touch the amp the hum reduce a little bit but not completly. I dont want to start buying things to try to remove the issue. I sent an email to Xduoo. Wil wait for the reply and then i will look into the issue again.
> 
> For now, i have to say that this amp produces a wonderful sound with my HD600s. Dispite this noise issues, the amp is absolutly fantastic with the senns. To be honest i was a bit desapointed with the HD600. I EQued them and was able to keep them for some time as the sound was more to my liking. But never totaly satisfied and lost in the music. The TA-26 was a last shot. And it was the right one. Beautiful sound. All kinds of music sound amazing to me.
> 
> ...


I have DAC Topping D10s connected before the TA-26 and I also had problems with interference, but it wasn't hum. Thanks to the ground loop, I received noise from the CPU, GPU and HDD from my PC via the USB cable to the DAC. I temporarily disconnected the ground wire at the power cord and the interference stopped. Then I already knew where the problem was and everything was solved by the already mentioned USB isolator Topping HS01. Of course, I reconnected the power supply ground wire.


----------



## ProAcTivo

muchacho said:


> I have DAC Topping D10s connected before the TA-26 and I also had problems with interference, but it wasn't hum. Thanks to the ground loop, I received noise from the CPU, GPU and HDD from my PC via the USB cable to the DAC. I temporarily disconnected the ground wire at the power cord and the interference stopped. Then I already knew where the problem was and everything was solved by the already mentioned USB isolator Topping HS01. Of course, I reconnected the power supply ground wire.


Thank you. I will look into that topping and the ifi sugestions. Maybe is as simple as insert one of those.


----------



## muchacho

Honestly, I have met with a hum so far with one vacuum tube, a Russian 6N8S from 1989, but for the price of 6USD I did not expect a miracle. After approx. After 80 hours of burning, the hum level has dropped, but when there is no signal to the amplifier, I hear very little hum in the right channel. And the tube also suffers from microphone ... The 6N8S has ended up in the stand and the new Tung-Sol and EH are in perfect order.


----------



## iFi audio

hmscott said:


> My "hum / Buzz / Whistle" problem was EMI/RFI noise induced into the 5V powerline Ground of the USB connection from my PC (GPU mostly) to my Topping D90 DAC, so my solition was the iFi* iDefender+* is for those battling with noisy audio due to unwanted ground loops in their audio chain:
> 
> iFi iDefender+
> https://ifi-audio.com/products/idefender-plus/



Hey, thanks for your feedback and I'm glad to read that our iDefender+ helped you out with that noise issue. Thanks!


----------



## ColSaulTigh

muchacho said:


> I have DAC Topping D10s connected before the TA-26 and I also had problems with interference, but it wasn't hum. Thanks to the ground loop, I received noise from the CPU, GPU and HDD from my PC via the USB cable to the DAC. I temporarily disconnected the ground wire at the power cord and the interference stopped. Then I already knew where the problem was and everything was solved by the already mentioned USB isolator Topping HS01. Of course, I reconnected the power supply ground wire.


I have the Topping HS01 as well and it fixed my problem.  I later put an Emotiva power conditioner inline before my surge suppressor and that got rid of any noise in the system.  Everything is now inky black with no hums or buzzes.


----------



## lma333

Hi everyone, 

I’m in the middle of discovering the realm of tube amp for a couple of weeks now and i would love to get my first one soon.
My goal is to drive my Meze Liric ( planar, 30ohms/100db sensitivity) and my Focal Stellia( dynamic driver, 35ohms/106 sensitivity).
i’m looking for a very “tubie” sound 
from what i understand OTL amp like the ta-26 are not suitable for my headphones but seems to have the most “tubie” sound of all xduoo amps…
the ta-30 is a OTL?? Or a hybrid?? I Don’t know to be honest, couldn’t fine the info 

For those who has a ta-20/ta-30 AND a ta-26 , can you please tell me the difference in “tubiness” sound from these amps please?

other question : if i use the ta-26 as a pre-amp and connect it to my Fiio K9 pro, now is it suitable for my heaphones?
Do i loose some of the ”tubiness” sound by using the K9 as an amp?


Hope i’m not asking too much questions in one shot 
Thank you very much in advance guys


----------



## -Darkstar-

Much of the "tube sound" comes from output tubes. Hybrid designs like the TA-30 and TA-20 will have some midrange bloom and warmth compared to most solid-state amps but not as much compared to all tube design like the TA-26. Of course, the bass response will be better with the TA-30/20 compared to the TA-26, especially with lower impedance cans like yours. The TA-26 should drive your Meze and Focals to fairly high volume, but I imagine it has a fairly high output impedance and your bass might be soft. It would pair better with high impedance cans like some of the Senns or Beyers. 

I have a TA-30 and it's a pretty good all in one solution. It has a ton of power, a pretty good DAC and uses common tubes. It does sound different from my all tube HP8Mk2 and that isn't necessarily a bad thing.


----------



## muchacho (May 17, 2022)

Good day,
I would like to ask if anyone in TA-26 has experience with the PSvane UK-6SN7 preamplifier tube? Or with which amplifier tube (6AS7G, 6N5S, 6080) ? But I'm interested in your opinion on UK-6SN7 ...


----------



## ProAcTivo

muchacho said:


> Good day,
> I would like to ask if anyone in TA-26 has experience with the PSvane UK-6SN7 preamplifier tube? Or with which amplifier tube (6AS7G, 6N5S, 6080) ? But I'm interested in your opinion on UK-6SN7 ...


Hi. I never heard it. But a friend of mine had it and liked it a lot. He thougt the PSvane bringed more clarity to the sound compred with the Shuguang Black Treasure. But for some systems could be too much. Nothing like try it in your own system.


----------



## muchacho

My point is to find the best playing tube for the TA-26 from the current production, but at a reasonable price. Well rated is from PSvane 6SN7-SE, but they are sold at a local dealer only in pairs and a couple of these tubes are for the price of almost the entire amplifier. That's why I'm looking at the UK-6SN7 tube, which has an acceptable price for me. That's why I'm finding out if anyone has the experience and evaluation of the sound of this preamplifier tube in the TA-26.


----------



## hmscott (Jun 6, 2022)

I've purchased a great little accessory for my TA-26 or any headphone amp with only a 6.35mm connection:

DD ddHiFi DJ65B 6.35mm Male to 4.4mm Female Audio Adapter for Desktop Amplifier
https://hifigo.com/products/dd-hifi-dj65b?variant=42531382886639
https://www.aliexpress.com/item/1005003981015647.html


(photo credit to ddHifi, lifted from hifigo.com )

What a relief, now I can swap back my custom length GUcraftsman 6n Silver 4.4mm headphone / extension cables on my Headphones and IEM's instead of being stuck with the short stock 6.35mm/3.5mm cables!

I had been swapping cables on my headphones/IEM's when listening between my TA-20 4.4mm / XLR output and my new TA-26 with only the 6.35mm output.  I finally gave up and kept the stock 6.35mm/3.5mm cables on all of my headphones / IEM's so I could easily move my headphones between both amps

I was a bit concerned about using this as I thought there was no safe way to convert between balanced and SE using an adapter.  IDK what is in this new adapter, but I don't notice any audio degradation, to my ears there is a big improvement in the audio. 

Is anyone else using this adapter?

Update: My ddHiFi DJ65B 6.35mm Male to 4.4mm Female Audio Adapter has been working great!


----------



## ProAcTivo

Hi everybody. So i recently bought a Sylvania 6SN7GT (bad boy) and im realy liking the sound in my TA-26. My question is if for being a GT and not a GTA/B the TA-26 is not going to "finish" this tube soon. Im asking because i read something online about the Darkvoice stating that 6SN7GT have diferent specs and are not optimal for use with that amp as it will be depleted much sooner than a 6SN7GTB for example.. i have no technical knowlage.. thank you


----------



## hmscott (Jun 23, 2022)

ProAcTivo said:


> Hi everybody. So i recently bought a Sylvania 6SN7GT (bad boy) and im realy liking the sound in my TA-26. My question is if for being a GT and not a GTA/B the TA-26 is not going to "finish" this tube soon. Im asking because i read something online about the Darkvoice stating that 6SN7GT have diferent specs and are not optimal for use with that amp as it will be depleted much sooner than a 6SN7GTB for example.. i have no technical knowlage.. thank you


I've asked Xduoo, as some amps are designed to run at the higher plate voltages possible on the upgraded GTA / GTB versions, but that is to deliver high wattage output from output tubes for speakers.

Xduoo doesn't need to push the 6SN7 tubes as hard in the TA-26 is a headphone amplifier with much lower output wattage required.

Per response from Xduoo the TA-26 runs the plate voltage within the original 6SN7GT range.  Xduoo answered that the 6SN7GT, GTA, GTB, and GTC are all compatible - as is the 5962.

A 1957 CBS Hytron 5962 is currently in my TA-26, and it is one of my favorite sounding tubes in the 6SN7 position of my Xduoo TA-26.

I've posted before on this subject,  you can search this thread and others, here's a quick search within this thread for my posts for "plate voltage"
https://www.head-fi.org/search/9673...c[thread]=682282&c[users]=hmscott&o=relevance

Here is a nice article on tube rolling on the Xduoo TA-26.  It has a lot of interesting info, but doesn't seem to have spoken with Xduoo directly.  I've found it helpful to read as much as I can find, and then ask directly service@xduoo.com with any lingering questions:
https://audiofool.reviews/tube-rolling-the-xduoo-ta-26/


----------



## ProAcTivo

Thank you for all the info.

So, i will have some tube rolling to do tomorrow. 
I will have:
1-Tung-Sol 6SN7GTB tall d getter(usa) 
2-Tung-Sol 6SN7GTB (russian new production)
3-Sylvania 6SN7GT botton getter (bad boy i think)
4-Marconi 6SN7 (rare and insanly expensive)
5-Unknown 6SN7GT short bottle, side getter, faded green label, black base(Sylvania?)
6-RCA 6SN7GTB Coinbase

I will post my findings 😀


----------



## ProAcTivo (Jun 8, 2022)

Well, my first review.

RCA 6SN7GTB Coinbase - Didn´t work 




The Tung-Sol 6SN7GTB USA made- The bass is not so full and prominent as in the other tubes. Is punchy, not bloated at all. The sound stage is wide, with good separation of all elements of the music. This tube is really on the brighter side compared to the others. Good and clear treble. This tube is the more Solid State like than all the other tubes. I use a EQ for my Sennheiser HD600 that works really well with this tube. For all the other tubes i had to change the EQ profile to another less "bass heavy". Second row music experience. Everything is in front of me and i can see all the instruments and sound stage is really wide. I love these for dance/pop and rock music. Very punchy.




The Tung-Sol 6SN7GTB New Russian Made - Very soft tube. Less punchy that the old USA version. Pleasant sound but a bit faraway in the center. Very laid back. Sound is clear without too much bass but not very defined. Third row music experience.




Unknown 6SN7GT - Nice sound but too much bass. Not so detailed.




Sylvania 6SN7GT - Very sweet, but also detailed. Sound is fuller than the Tung-Sols. More body. Bass is also more prominent and present. The center of the stage is closer now especially noticeable with vocals. Overall very balanced sound with very sweet treble and open mid range. This one gives the music a warm welcome. First row music experience. Very close to everything, with a somehow narrower soundstage compared to the Tung-Sols.







Marconi 6SN7GTB - This one is different. This is a Sylvania in steroids. The sound is now all around your head. The characteristics are very close to the Sylvania, but the presentation is different. This is a center stage music experience. You are not looking at the music, you are in the middle of it. Is quite strange to me to be honest. For the first time, i fooled myself to think i was listening to my old pair of ProAc Studio 100 speakers. I don't know if is better than the Sylvania or if i'm going to get used to this kind of headphones experience but is quite exciting. Also, i got this for less than 15$ so, i think i made a good deal.


----------



## Yanto

Hi all. 
Last week I bought an Xduoo 602 tube hybrid amp to use with my Grado SR325x. 
I’ve swapped the stock tubes for a pair of Voskhod 6J1P’s. Quite a noticeable improvement in sound quality immediately. I’ve used these for about 12 hours now.
Have also got some GE JAN 5654w and Sylvania 9003 1980 on order.
I’m new to all of this tube swapping and I appreciate it is a big rabbit hole, and very subjective.
Has anyone got experience with this amp and classical music please? If so can you tell me which tubes you think suit that genre please? Thanks in advance


----------



## rprodrigues

Anyone with both Xduoo TA26 and Little dot mkII ?
I'd like to know how TA26 stands against dot mkii.

@Wiljen Have you tested both?


----------



## Wiljen

rprodrigues said:


> Anyone with both Xduoo TA26 and Little dot mkII ?
> I'd like to know how TA26 stands against dot mkii.
> 
> @Wiljen Have you tested both?


I do have both. Output power on the Ta26 is about double that of the Little Dot MkII so different target headphones I would think.   The Ta-26 does well with Beyer 600 Ohms and the big Sennheisers (HD660, HD800) and gives a bit more headroom than the little dot does with the same.   

The Little dot has less options in power tubes without needing adapters as the 6N6 isn't directly interchangable with much else without some form of adapter or rewire.   The 6AK5 is common and cheap so that is a plus in favor of the little dot.    Tubes for the Ta-26 are more plentiful (6SN7 driver, 6AS7 Power) but there are a ton of junk tubes out there, especially for the 6SN7 and good tubes are more expensive than those for the Little dot.    Tube availability favors the Ta-26 but cost per tube favors the little dot.   

I really like the Ta-26 and think it is better made than the little dot as the case is heavier and better finished, but it also uses pcb where the little dot still uses a lot of point to point wiring and is easier to modify if desired.     It will all come down to what you intend to do with it.  If you like to tinker and change caps and rewire sockets etc the little dot will be easier to work with.  If you want to tube roll it but not change internals, the Ta-26 has a wider range of options, and if you just want to use it and never tinker at all, the Ta-26 has more output power but also a bit higher initial cost and a bit more up keep cost when it comes time to replace tubes.

Hope that helps.


----------



## rprodrigues (Jun 30, 2022)

@Wiljen

Thank you!

From what you told me, mkII seems to be a good starting point to (non-hybrid) tube amps. Is it enough to get a true taste of how tube amps can sound?


----------



## Wiljen (Jun 30, 2022)

rprodrigues said:


> @Wiljen
> 
> Thank you!
> 
> From what you told me, mkII seems to be a good starting point to (non-hybrid) tube amps. Is it enough to get a true taste of how tube amps can sound?



The little dot is good for getting started and there are enough tube options for the 6J1 (which translates to the 6AK5 or 5654 in US tube designations) that you can get an idea what tube rolling is all about.  I'd leave the power tubes alone and try 3 or 4 different pairs of 6AK5s in the front two sockets.  Personal choices would be a Raytheon 6AK5, a Western Electric 403b, and a GE 6096 pair.   Changing out the front two tubes (the drivers) will make the most difference to the sound and there is considerably more variety available than for the rear two 6NP power tubes and any change made to the front two is then magnified as it passed the rear tubes.   You will want a high impedance headphone to test with.  I'd see about finding an early AKG 240 or a Beyerdynamic DT990 (either in 600 Ohm form)  or a HD6xx, 660, or 800 in the Sennheiser line.


----------



## rprodrigues

Wiljen said:


> The little dot is good for getting started and there are enough tube options for the 6J1 (which translates to the 6AK5 or 5654 in US tube designations) that you can get an idea what tube rolling is all about.  I'd leave the power tubes alone and try 3 or 4 different pairs of 6AK5s in the front two sockets.  Personal choices would be a Raytheon 6AK5, a Western Electric 403b, and a GE 6096 pair.   Changing out the front two tubes (the drivers) will make the most difference to the sound and their is considerably more variety available than for the rear two 6NP power tubes and any change made to the front two is then magnified as it passed the rear tubes.   You will want a high impedance headphone to test with.  I'd see about finding an early AKG 240 or a Beyerdynamic DT990 (either in 600 Ohm form)  or a HD6xx, 660, or 800 in the Sennheiser line.



Thank you again!

I will try to get a mkII first since I can get it at half the price of TA26. I already have some high impedance cans as a dt990 250 and a hd6xx, and even some earbuds with impedances from 150 to 600 Ohm. I'd like to hear how they sound once paired with an  OTL tube amp.

I do appreciate your responses. They are a valuable guide for dudes who are interrested in TA26 or Little dot mkII.


----------



## kibot

Hi guys!
I want to buy some new headphones - which of this would be better for TA 26 :

*Audeze LCD - 2 Classic*

or

*Monolith by Monoprice M1570  *


----------



## Wiljen

kibot said:


> Hi guys!
> I want to buy some new headphones - which of this would be better for TA 26 :
> 
> *Audeze LCD - 2 Classic*
> ...


I'd go with the LCD-2 Classic - a bit easier to drive (higher sensitivity) and a bit better pairing with the Ta-26 to my ear.


----------



## kibot (Jul 3, 2022)

Wiljen said:


> I'd go with the LCD-2 Classic - a bit easier to drive (higher sensitivity) and a bit better pairing with the Ta-26 to my ear.


Great thanx for answer
In your opinion what version of LCD 2 would be better  - open or closed back ?(for rock/metal music - i like warm and dark sound)


----------



## hbmorrison

I have a TA-26 on order from Shenzhen Audio. Hopefully it will ship early next week. I was disappointed that I had to pay an extra delivery fee (to the UK) because of the weight of the TA-26 but it was on sale and I should get it in my hands quicker so fair enough. I'm really looking forward to hearing it and trying it out as s pre-amp into some 50 year old Wharfedale Linton speakers 🥰


----------



## Wiljen

kibot said:


> Great thanx for answer
> In your opinion what version of LCD 2 would be better  - open or closed back ?(for rock/metal music - i like warm and dark sound)


Warm and Dark would be more the territory of the closed back although neither is really very warm or dark.  My preference is for the open-back with its better imaging and stage.


----------



## kibot

Wiljen said:


> Warm and Dark would be more the territory of the closed back although neither is really very warm or dark.  My preference is for the open-back with its better imaging and stage.


But i think that it would be warm and dark with ta 26 (like it was with my hd 600 - it has perfect and warm sound with it instead of solid state amps)


----------



## hbmorrison

I forgot to ask: does anybody have suggestions for a reasonably priced DAC to pair with the TA-26. I'd be looking for one that has optical-in.

I have the JDS Labs Atom DAC+ or SMSL Sanskrit pencilled in as possibilities (expecting the Atom DAC+ to be pretty clean and the Sanskrit to be on the smoother side).


----------



## Wiljen

hbmorrison said:


> I forgot to ask: does anybody have suggestions for a reasonably priced DAC to pair with the TA-26. I'd be looking for one that has optical-in.
> 
> I have the JDS Labs Atom DAC+ or SMSL Sanskrit pencilled in as possibilities (expecting the Atom DAC+ to be pretty clean and the Sanskrit to be on the smoother side).


I like the Atom+ in that role.


----------



## CJG888

hbmorrison said:


> I forgot to ask: does anybody have suggestions for a reasonably priced DAC to pair with the TA-26. I'd be looking for one that has optical-in.
> 
> I have the JDS Labs Atom DAC+ or SMSL Sanskrit pencilled in as possibilities (expecting the Atom DAC+ to be pretty clean and the Sanskrit to be on the smoother side).


Is the TeraDak Chameleon still available?


----------



## Milen007

Anyone have this amp with hifiman edition xs? I have this headphone and would like to know if this amp can drive it nice and good


----------



## hbmorrison (Jul 11, 2022)

My xDuoo TA-26 came in the post from Shenzhen Audio today.






It was very well packaged and there were no customs issues with DHL (to the UK). Pretty great service.

I have my DT770s plugged in right now so that I can have a sneaky listen at the sound while I let the tubes settle a bit. There is a hum coming from the unit but I am not going to pass judgement until the whole thing has had a bit of a run.

All in all I am really pleased and I am looking forward to giving it a spin with my other headphones. It is also going to be pre-amping my living room speakers, which should be fun.


----------



## Silver Wolf (Jul 12, 2022)

Damn it, now I'm awaiting delivery of a TA-26 also.... Finger slipped on buy now button by accident, you know how it goes lol.

Y'all been teasing so much I couldn't resist the dark side call of OTL giggle... I've been very happy with all the hybrid xDuoo gear so far I've had so why not? I did have a set of DT880 600ohm turn up last week I have yet to play with (by that I mean fix lol, there a broken pre-loved set I got cheap) but they would be perfect for use with the TA-26. I got a few 250/300 ohm cans but it'd be cool to use the DT 880 with OTL.... Happy Days...Oh now I'm gonna need more tubes hehehehe


----------



## hbmorrison

So its early days but the first thing I have noticed with the TA-26 is the really deep bass extension. It really gets down there on my HD6xx's and my 250Ohm DT770s are really fun. I've gone as far as saving the songs that have noticeably deep bass so that I can compare them on my other amps. 

I have also tried the TA-26 pre-amping my Arcam Diva A75 that I have wired up to a pair of ancient Wharfedale Linton speakers. It sounds promising but I need to do a lot more listening to see if it is a worthwhile longer term option. My partner is on night shift so I'll have to stick to the headphones for now 😈😁


----------



## hbmorrison

Silver Wolf said:


> Damn it, now I'm awaiting delivery of a TA-26 also.... Finger slipped on buy now button by accident, you know how it goes lol.



That happens quite a lot in this household 😁 Going by how my DT770s sound the DT880s should sound amazing! I sold my DT880s ages ago but now I'm tempted again....


----------



## Silver Wolf (Jul 12, 2022)

hbmorrison said:


> That happens quite a lot in this household 😁 Going by how my DT770s sound the DT880s should sound amazing! I sold my DT880s ages ago but now I'm tempted again....


I've got the DT1770 (modded/rolled 250ohm) and HD6XX 'n I'm wondering about sending the pre-out to my monitors 'n wireless gear if I like the sound... all good fun, I'm thinking of using Topping D30 pro dac to feed the TA-26. I use i currently to feed a xDuoo TA-20 via BAL as I really enjoy it.

I only paid postage for the DT 880 as they were non functioning and minus pads so I've got nothing to lose on them really.... I've got lots of pads 'n can fix most other things etc and if not Beyer is good about selling parts so it should be good fun 'n work out to be all good


----------



## hbmorrison

Silver Wolf said:


> I'm thinking of using Topping D30 pro dac to feed the TA-26. I use i currently to feed a xDuoo TA-20 via BAL as I really enjoy it.


I'm currently using my old Schiit Modi 2 Multibit with the TA-26 but I'm thinking of getting one of the AK4493 based DACs for a cleaner input. Either the Topping E30 or SMSL Sanskrit.


----------



## jonathan c (Jul 12, 2022)

@hbmorrison , if your source is CD, you should be aware of this:


----------



## Ufanco

hbmorrison said:


> I'm currently using my old Schiit Modi 2 Multibit with the TA-26 but I'm thinking of getting one of the AK4493 based DACs for a cleaner input. Either the Topping E30 or SMSL Sanskrit.



I recently picked up a Ares ii dac to go with the Xduoo TA20. The synergy of the ares ii and ta20 produces excellent sound imho. Depending on mood using either the hydro 12bh7 or Sylvania 12BH7a tubes. 
Really amazing how well this amp has scaled up as system improves.


----------



## Silver Wolf (Jul 13, 2022)

hbmorrison said:


> I'm currently using my old Schiit Modi 2 Multibit with the TA-26 but I'm thinking of getting one of the AK4493 based DACs for a cleaner input. Either the Topping E30 or SMSL Sanskrit.


Out of those two I'd look towards the SMSL or something else maybe....As below


jonathan c said:


> @hbmorrison , if your source is CD, you should be aware of this:


Not the only Topping DAC with issues like this, the D30 pro is also known to have issues when connected to CD players, Tv's etc via toslink/coax... Makes me unhappy as an D30 pro owner that loves everything else about the DAC, has put me off the brand if I'm honest.


----------



## jonathan c

Silver Wolf said:


> Damn it, now I'm awaiting delivery of a TA-26 also.... Finger slipped on buy now button by accident, you know how it goes lol.


Simple physics!  ‘finger’ = N pole, magnet 1; ‘buy now button’ = S pole, magnet 2…..🤣🤣


----------



## Ufanco

Man hate when the finger slips and for some reason mine does it well browsing tubes. I have wayyyy more than I need and one of these days need to pick the best 7 pairs and sell the rest.


----------



## hbmorrison

jonathan c said:


> @hbmorrison , if your source is CD, you should be aware of this:



Thanks for that. My source is mostly a streamer and sometimes USB to my phone so hopefully it shouldn't be an issue. I am leaning towards the SMSL anyway, or possibly the JDL Labs Atom DAC+. Either that or I might rearrange everything.


----------



## hbmorrison

hbmorrison said:


> Either that or I might rearrange everything.


So I rearranged everything.



Ok I know I should have a hifi cabinet but it sort of works? And both amps behave with the R1 balanced outs connected to the MJ2 and the SE outs connected to the TA-26.

I didn't think the R1 / TA-26 combo would work but boy does it work. I'm listening to "The Earth Is Not A Cold Dead Place" by Explosions In The Sky on my HD6XXs and it is so sonorous and velvety with a deep bass rumble. Reminds me of when I heard them playing it live.

I'm sure this is by no means "transparent" but wow I don't care.


----------



## jonathan c

hbmorrison said:


> So I rearranged everything.
> 
> Ok I know I should have a hifi cabinet but it sort of works? And both amps behave with the R1 balanced outs connected to the MJ2 and the SE outs connected to the TA-26.
> 
> ...


•  That is an effective and visually appealing setup. ☑️
•  If your system reminds you of live sound (since it cannot be live sound), what else matters? 😄


----------



## hbmorrison

By the way I am really surprised and impressed by how good my old DT770 250ohms sound on the TA-26. I'm kind of tempted to get a pair of DT990s now, which I didn't think I'd ever say.


----------



## kibot (Jul 15, 2022)

Hello guys!
I want to buy some new cans for my headphone collection))
So can anyone advise me please headphones with warm and dark sound for TA 26 (price under 500$) ??
I have DT 770 250 Ohm and HD600 - they sounds awesome (especially HD600) but i want something else a little more darker and warmer))


----------



## hbmorrison

kibot said:


> I have DT 770 250 Ohm and HD600 - they sounds awesome (especially HD600) but i want something else a little more darker and warmer


The Hd6xx on Drop is warm and darker.


----------



## kibot (Jul 15, 2022)

hbmorrison said:


> The Hd6xx on Drop is warm and darker.


Thank you man but i dont want anyone of HD-series ,maybe HD650 some time but not now (I love my HD600😎)


----------



## Silver Wolf (Jul 19, 2022)

Silver Wolf said:


> Damn it, now I'm awaiting delivery of a TA-26 also.... Finger slipped on buy now button by accident, you know how it goes lol.
> 
> Y'all been teasing so much I couldn't resist the dark side call of OTL giggle... I've been very happy with all the hybrid xDuoo gear so far I've had so why not? I did have a set of DT880 600ohm turn up last week I have yet to play with (by that I mean fix lol, there a broken pre-loved set I got cheap) but they would be perfect for use with the TA-26. I got a few 250/300 ohm cans but it'd be cool to use the DT 880 with OTL.... Happy Days...Oh now I'm gonna need more tubes hehehehe


Somebody wasn't meant to be here for a month or so yet, but turned up early...Nice surprise really, so burning NOS tubz in 'n chimpin a listen here'n there already... 

New Horse in the stable! (I'm going to have to have a look at fixing/modding those DT880 600ohm's I scored recently sooner than expected giggle...)


----------



## dsrk

Silver Wolf said:


> Somebody wasn't meant to be here for a month or so yet, but turned up early...Nice surprise really, so burning NOS tubz in 'n chimpin a listen here'n there already...
> 
> New Horse in the stable! (I'm going to have to have a look at fixing/modding those DT880 600ohm's I scored recently sooner than expected giggle...)


My TA-26 will arrive tomorrow. Your headphones HD6XX and LCD2C? 
Nice cables, what are those?


----------



## Silver Wolf (Jul 19, 2022)

dsrk said:


> My TA-26 will arrive tomorrow. Your headphones HD6XX and LCD2C?
> Nice cables, what are those?


The headphones being used there are the HD6xx (lightly modded), yes I have on the side there the LCD2C but not used/tired those with this amp. Don't think they would be a good impedance match but who knows.... Not really tried much yet just letting things do their thing for a few hours...... The cables are my own design/make


----------



## dsrk

Silver Wolf said:


> The headphones being used there are the HD6xx (lightly modded), yes I have on the side there the LCD2C but not used/tired those with this amp. Don't think they would be a good impedance match but who knows.... Not really tried much yet just letting things do their thing for a few hours...... The cables are my own


Wow, those cables look better than many custom cables. Good work
My headphones are also same HD6XX and LCD2C I am getting TA-26 for my HD6XX, LCD2C sounds great on my EF400.


----------



## kibot

dsrk said:


> Wow, those cables look better than many custom cables. Good work
> My headphones are also same HD6XX and LCD2C I am getting TA-26 for my HD6XX, LCD2C sounds great on my EF400.


Hi ✌
What can you say about the sound LCD2C with TA26 ?(i want to buy it in future)


----------



## dsrk (Jul 19, 2022)

kibot said:


> Hi ✌
> What can you say about the sound LCD2C with TA26 ?(i want to buy it in future)


Hi,
I will receive it tomorrow, I will let you know.
From what I read so far TA-26 is best with cans with high impedance.


----------



## kibot

dsrk said:


> Hi,
> I will receive it tomorrow, I will let you know.
> From what I read so far TA-26 is best with cans with high impedance.


Ok i will wait - great thanx for answer!!
LCD2C have not so small impedance - its 70🤷‍♂️


----------



## hbmorrison

I have tried my LCD-3s - which have a nominal impedance of 110ohm I think? - on my TA-26 and I thought the bass sounded a bit muddy. I will need to give them another listen but I wonder if planars won't get enough current for the bass to be clear?


----------



## dsrk (Jul 22, 2022)

Hi Guys,

Received my TA-26 a few hours ago. I let it on for a few minutes and immediately plugged in my HD6XX (couldn't wait anymore ). Oh boy it was something I never heard of HD6XX sounding and I am loving it. This is my first OTL AMP.
I will give it some more time and let you know my impressions.




kibot said:


> Ok i will wait - great thanx for answer!!
> LCD2C have not so small impedance - its 70🤷‍♂️


Man it was terrible I heard LCD2C sounded out of any AMP I tested until now. LCD2C is a big NO with TA-26, there is hardly any bass and sound is too muffled, grainy and distorted.
Passion for sound on youtube measured the output impedance of TA-26 and it's 90ohms which not at all good news for low impedance headphones and especially planars with low sensitivity and low impedance.
If it's going to change after burn in or whatever I will let you know.


----------



## dsrk

Guys,

Is it a good idea to cool the AMP down with a portable fan or let it run hot for optimal performance?


----------



## roderickvd

Most tubes sound better when hot. YMMV


----------



## fanteskiller

Silver Wolf said:


> Somebody wasn't meant to be here for a month or so yet, but turned up early...Nice surprise really, so burning NOS tubz in 'n chimpin a listen here'n there already...
> 
> New Horse in the stable! (I'm going to have to have a look at fixing/modding those DT880 600ohm's I scored recently sooner than expected giggle...)


RCA sounds better?


----------



## roderickvd

I keep confusing RCA tubes with single-ended cables…


----------



## kibot

dsrk said:


> Hi Guys,
> 
> Received my TA-26 a few hours ago. I let it on for a few minutes and immediately plugged in my HD6XX (couldn't wait anymore ). Oh boy it was something I never heard of HD6XX sounding and I am loving it. This is my first OTL AMP.
> I will give it some more time and let you know my impressions.
> ...


Great spasibo for answer 🙏🙋‍♂️
So what can you advice for TA26 with dark and maybe a little warm sound under 550$  ?


----------



## dsrk

kibot said:


> Great spasibo for answer 🙏🙋‍♂️
> So what can you advice for TA26 with dark and maybe a little warm sound under 550$  ?


No problem .
You already have the beyers and HD600, I don't know any other headphone with high impedance in that price range that beats the warmth and smoothness of HD600/650/6XX especially on tubes.


----------



## kibot

dsrk said:


> No problem .
> You already have the beyers and HD600, I don't know any other headphone with high impedance in that price range that beats the warmth and smoothness of HD600/650/6XX especially on tubes.


I have hd600 and thats my lovely ones with ta 26))
What about Sony mdr z7 and Neumann NDH 20 ??? Or maybe KLH Ultimate One?


----------



## dsrk

kibot said:


> I have hd600 and thats my lovely ones with ta 26))
> What about Sony mdr z7 and Neumann NDH 20 ??? Or maybe KLH Ultimate One?


Never heard the Sony's. NDH 20s are very neutral and I read that they take tubes well but I never heard them on tubes, I liked them but they were uncomfortable for me. Not sure if KLH with 32 ohms impedance pairs well with TA-26.

Anyone else who heard them on TA-26 can chime in.


----------



## kibot

So anyway great thank you for impressions and advices🙋‍♂️


----------



## Silver Wolf (Jul 24, 2022)

dsrk said:


> Guys,
> 
> Is it a good idea to cool the AMP down with a portable fan or let it run hot for optimal performance?



I also run fans for any of my audio/visual gear, even in my dedicated HT room set-up (different brand and auto temp sensing but same deal)-(SS audio gear also gets hot in my set-up/s) when it gets a bit too warm, I use small 80mm remote speed controlled fans designed for A/V cooling type use on their lowest setting and share/limit power. Keeps them quiet as and is just a slight breeze/moving air for cooling. I don't have mine so close and more aimed at the transformer with slight tilt so air does flow towards tubes. Most of my gear is in tight compromised spaces with reduced normal air flow and I live in very hot country and it depends on tubes fitted as some do run fairly cool. If the gear (not actual tubes as they will run hotter obviously) is running below 40 Celsius it's fine, if hotter I assist cooling.

Pretty cheap also $20 for a 2 fans and controllers etc...
edit update to add link to fans I use for any interested
https://www.amazon.com.au/gp/product/B082PXY572/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1



fanteskiller said:


> RCA sounds better?


Not for my ears, currently I'm much preferring the NOS BVA Brimar on the set-up I'm listening with... But each to their own, it's all good!


----------



## dsrk

Silver Wolf said:


> I also run fans for any of my audio/visual gear, even in my dedicated HT room set-up (SS also gets hot in my set-up/s) when it gets a bit too warm, I use small 80mm remote speed controlled fans designed for A/V cooling type use on their lowest setting and share/limit power. Keeps them quiet as and is just a slight breeze/moving air for cooling. I don't have mine so close and more aimed at the transformer with slight tilt so air does flow towards tubes. Most of my gear is in tight compromised spaces with reduced normal air flow and I live in very hot country and it depends on tubes fitted as some do run fairly cool. If the gear (not actual tubes as they will run hotter obviously) is running below 40 Celsius it's fine, if hotter I assist cooling.
> 
> Pretty cheap also $20 for a 2 fans and controllers etc...
> edit update to add link to fans I use for any interested
> https://www.amazon.com.au/gp/product/B082PXY572/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1


Thanks.
I am also aiming the fan more towards the transformer. It's can get very hot in India as well especially during summer the temperature goes above 40°C. The fan I am using also comes with three speeds. I am using it at the lowest speed.


----------



## hmscott (Jul 24, 2022)

dsrk said:


> Guys,
> 
> Is it a good idea to cool the AMP down with a portable fan or let it run hot for optimal performance?


No, please don't cool tubes 

The TA-26 amp/components are designed to take the fully loaded heat output, so there is no need to "cool" it.

In fact the whole point of the "heater" is to generate heat to an optimal temperature to get optimal characteristics out of the components.  The stable temperature is where everything is designed to operate - component values and tuning derived from their combination at their stable temperature range - not cold, or cooled.

Using a "single-sided" cooler as in the photo might also create odd currents - one half of the tube is cooler/colder than the "hot" side, migration of heat from the hot side to the cool side, all kinds of weirdness.

Imagine cooling one side of a grill with a fan... gonna turn out some weird burgers and franks. 

But, I also wouldn't run equipment stacked under the TA-26 with both powered up at the same time.  The heat from the TA-26 is gonna "fry" components not designed to run that hot, and the TA-26 isn't going to need the added heat rising from the device below it.

Best to keep them apart by a couple of inches - side by side - with the TA-26 not too close to anything like monitors or disk drives.  And I wouldn't want any device downwind from the TA-26 with the heat from the TA-26 blowing onto a device.

I let the heat rise on it's own, apart from each other.

But, if the heat from the TA-26 and other tube/hot components is filling the room with too much heat, you can make a hood + vent tube - with an exhaust fan at the exhaust end - to pull heat out of the room.

It is important to keep the Humans and Animals cool


----------



## dsrk

hmscott said:


> No, please don't cool tubes
> 
> The TA-26 amp/components are designed to take the fully loaded heat output, so there is no need to "cool" it.
> 
> In fact the whole point of the "heater" is to generate heat to an optimal temperature to get optimal characteristics out of the components.  The stable temperature is where everything is designed to operate - component values and tuning derived from their combination at their stable temperature range - not cold, or cooled.


Sure, thanks.



hmscott said:


> Using a "single-sided" cooler as in the photo might also create odd currents - one half of the tube is cooler/colder than the "hot" side, migration of heat from the hot side to the cool side, all kinds of weirdness.
> 
> Imagine cooling one side of a grill with a fan... gonna turn out some weird burgers and franks.


HahaI felt the same after a while and running the fan like this just to cool the DAC panel down.


Is it okay to run fan like this or avoid the fan and use the exhaust fan instead?



hmscott said:


> But, I also wouldn't run equipment stacked under the TA-26 with both powered up at the same time.  The heat from the TA-26 is gonna "fry" components not designed to run that hot, and the TA-26 isn't going to need the added heat rising from the device below it.
> 
> Best to keep them apart by a couple of inches - side by side - with the TA-26 not too close to anything like monitors or disk drives.  And I wouldn't want any device downwind from the TA-26 with the heat from the TA-26 blowing onto a device.


I got the idea to use the fan because it was heating up the top panel of the DAC.



hmscott said:


> I let the heat rise on it's own, apart from each other.
> 
> But, if the heat from the TA-26 and other tube/hot components is filling the room with too much heat, you can make a hood + vent tube - with an exhaust fan at the exhaust end - to pull heat out of the room.
> 
> It is important to keep the Humans and Animals cool


I will try to run an exhaust fan and keep the TA-26 separate from the DAC.


----------



## screwdriver

xduoo ta 10r  with goldplanar gl2000 modded . i tube rolled - i find the northern electric 12au7 tube really good  along with th goldlion 12au7 . the psvane is not bad at all .


----------



## Ufanco (Jul 25, 2022)

hmscott said:


> No, please don't cool tubes
> 
> The TA-26 amp/components are designed to take the fully loaded heat output, so there is no need to "cool" it.
> 
> ...



Thanks for the excellent responce, I had a small fan cooling mine and the vibration was affecting sound quality.
My only concern is the 12bh7 run hotter than the 12ua7, so I'm using tube risers that raise the tube enough that heat is outside of the unit. 

The tube riser is an inexpensive and they make tube rolling easer. The only con is the tube protecters no longer fit.

@screwdriver my ta20 (used) had a set of northern electric 12au7 included. Considering there a newer product found the sound quilty is faily good, have to say was shocked at the price.
 I no longer use 12au7 with the TA20 but think I’ll pop in the NE 12au7 and give them another listen.


----------



## muchacho

I also use a tube saver so that they don't heat up the inside unnecessarily and the beauty of the tube glows. This protector pad can be printed on a 3D printer.


----------



## dsrk

Hi Guys, 

Can I use the aux out on TA-26 to a portable headphone AMP to get that tube magic to my LCD2C?


----------



## CJG888

Depends if it is an active preamp stage, merely a passive volume control or even a straight bypass circuit. Does the level on the outputs vary with the volume control?


----------



## dsrk

dsrk said:


> Hi Guys,
> 
> Can I use the aux out on TA-26 to a portable headphone AMP to get that tube magic to my LCD2C?


I bought Topping NX7 to use with my RS6 for portable use.
LCD2C sounds much better with TA-26 aux out to NX7 than headphone out on TA-26. It actually sounds better than 4.4mm out on EF400.


----------



## kibot (Aug 17, 2022)

dsrk said:


> I bought Topping NX7 to use with my RS6 for portable use.
> LCD2C sounds much better with TA-26 aux out to NX7 than headphone out on TA-26. It actually sounds better than 4.4mm out on EWow great thanx


Woow great thanx for impressions🙏👍


----------



## Silver Wolf (Sep 11, 2022)




----------



## Sp12er3

After getting my endgame solid state I'm craving for some Tube only ever dabble with small things like Bravo Audio Ocean and never liking that one much. 
Now how does the TA26 is faring in its QC and daily usage? Been hearing some inconsistencies with Darkvoice, but I hear the TA26 is much better built with better internals so looking around for more impressions.


----------



## vmiguel

Mine has some "scratch" noises when moving the volume pot between zero and one o'clock positions. 
If I rotate it repeteadly it goes away... just to be back next time I turn it on. 
Other than that, I love it.


----------



## Sp12er3

Hmm standard analog volume pot problem huh, OK, been using digital ones for years I forgot this one is pretty common.


----------



## mformoriarty

vmiguel said:


> Mine has some "scratch" noises when moving the volume pot between zero and one o'clock positions.
> If I rotate it repeteadly it goes away... just to be back next time I turn it on.
> Other than that, I love it.


Had that issue with the Magni Heresy. It tends to be dust and such stuck inside the potentiometer that is the volume knob. Nothing to worry about really, there are some lubricants that can fix the issue tho.


----------



## mformoriarty

Gentlemen,
Bought a TA-26 yesterday, it hasn't even shipped and I am already looking for recommendations as for tube rolling. Do you guys have any thoughts/suggestions? Don't actually wanna go overboard on the budget for tubes but I do wanna dip my feet into rolling. If any of you could pick just one pair of tubes for this amp, which one would it be? In other words, what would you consider endgame with this amp? I'll be using an iFi Zen DAC Signature as my source and the Sivga SV023. My Sundaras, being low impendace outside the recommended 60ohm range, don't look like a good pair for this.


----------



## Sp12er3 (Sep 25, 2022)

I'm mostly planning to drive my ADX5000 and T1 on it, which is 420 and 600 respectively, should be perfect with it,
Tho am wondering what it'd do with my Z1R also, I checked and its 64ohm, barely over the rec impedance of 60-600 ohm.


----------



## RONJA MESCO

Question for the board...Over the past two years I sold off my Xduoo XD-05 (found the OG XD-05 too dry and lifeless )  and a TA-03S (this tube amp is criminally underrated and a steal for what it is) and want to get back into the brand. I see the balanced XD-05 out there, but I do know there are other lower rung 05's with sold with better amp sections...any suggestions on which to choose? I just want to see my options out there on the lower end before I need to pony up cash for the balanced portable.


----------



## g0ldl10n

Couple quick questions for anyone that owns an Xduoo-TA 26. 

1. How many inches in between the two handles/rails flanking the tubes? 




2. Anyone use dual 6SN7 adapters to run tubes such as 6J7, 6C5, etc? 

Before I make this purchase, just want to verify my dual adapters are going to fit in between these rails. 

Thanks in advance!


----------



## Ufanco

Just got some nos 12bh7 tubes for the xduoo ta 20. They're kind of different so figured I’ll share some pics. If anyone has any info on them please let me know.


----------



## CJG888

I also use Westinghouse 12BH7s (as drivers for the 300Bs in my main amplifier). I believe they were manufactured by RCA (please correct me if I’m wrong here).


----------



## YanaMJ

Ufanco said:


> Just got some nos 12bh7 tubes for the xduoo ta 20. They're kind of different so figured I’ll share some pics. If anyone has any info on them please let me know.


Hello,

Could you help me about your socket savers? Where did you find them and are they easy to uninstall ?


----------



## mformoriarty

TA-26 (110v) arrived today. Using the stock tubes and basically no burn in. Using the Zen Dac signature V2 as source plus the Sivga SV023 and my foobar playlist. Comparing the TA-26 with the Zen Can Signature HFM headphone amp.
Started listening over an hour ago and I haven't stopped. This is honestly an amazing sound signature, even with the stock tubes (can't wait to start tube rolling). The bass feels like it goes deeper, getting some cool verticality I haven't experienced before. Soundstage feels almost as wide as the Sundaras with the added bonus of a lot of air and a natural reverb. As for clarity/details, it feels a bit clouded in some areas but that gives the music a natural tonality, mids feel a tad milder. At the same time, and this may sound contradictory, I'm getting more details that I haven't heard before and this is comparing to a solid state Zen Can Signature HFM. So far the only complaint is the same as with many audiophile brands. They dislike having a visible line on the knob. So as with my other amps, a little white nail polish fixes the job.


----------



## Ufanco

YanaMJ said:


> Hello,
> 
> Could you help me about your socket savers? Where did you find them and are they easy to uninstall ?


Bought them from Amazon and are easy to install an remove. I think this link is the ones I bought. 
https://www.amazon.com/Yibuy-2-7x2-...663820978&sprefix=9+pin+socket+,aps,83&sr=8-3


----------



## mayurs

Joining the Xduoo TA-26 club soon as I have ordered this amp and can't wait for it to arrive.

Since I already have a very nice collection of NOS 6080/6AS7G/5998 and 6SN7 tubes, I was looking for a DV or this as my second OTL that uses the same tubes to use as my everyday work amp to drive my HD600, HD650, R70X and Grado SR80X. 

I also intend to drive my SS class A headphone amp using this as a pre for my Ananda (coz I just don't like direct DAC to SS amp anymore, spoilt by my Felika Euforia pre to my speaker power amp to drive the extremely tough to drive HiFiMan HE6SE which sounded way better to my ears than the Arya and was brilliant with the Susvara as well.


----------



## Silver Wolf (Sep 25, 2022)

g0ldl10n said:


> Couple quick questions for anyone that owns an Xduoo-TA 26.
> 
> 1. How many inches in between the two handles/rails flanking the tubes?
> 
> ...









Oh and a better pic of the tubes I'm currently listening to for those into them. NOS Melz 1578 + MWT/GEC 6080/A1834 stubby, maybe I should get a riser for at least the back, looks funny being lower to me (Feng Shui 'n all) but then I prefer the look of ST style tubes.


----------



## LowBeat91

Is there a balanced tube pre amp from Xduoo?


----------



## mayurs

It's here, the TA-26 and first impressions are extremely positive. Love it with my HD600 and R70X which absolutely demand an OTL and frankly  are pretty much nonsense with most SS amps I have tried. The TA-26 is not the most resolving amp, atleast with the stock tubes, but then it's still very new and hardly burnt in. One thing that really stands out is the headspace. It even expands the relatively closed HD600 out of my head in all directions. I even tried the pre amp function to my SS Headphone amp and it was again mighty impressive driving my ER4XRs,  which sounded the best ever on my SS amp. I plan to stick with the stock tubes to fully run in the amp and then bring out my better tubes once it is ready.


----------



## dsrk

mayurs said:


> It's here, the TA-26 and first impressions are extremely positive. Love it with my HD600 and R70X which absolutely demand an OTL and frankly  are pretty much nonsense with most SS amps I have tried. The TA-26 is not the most resolving amp, atleast with the stock tubes, but then it's still very new and hardly burnt in. One thing that really stands out is the headspace. It even expands the relatively closed HD600 out of my head in all directions. I even tried the pre amp function to my SS Headphone amp and it was again mighty impressive driving my ER4XRs,  which sounded the best ever on my SS amp. I plan to stick with the stock tubes to fully run in the amp and then bring out my better tubes once it is ready.


I am doing the same with my low impedance headphones pre amp to Topping NX7.

TA-26 is my first OTL. HD6XX on TA-26 is the best I heard it sound.


----------



## mformoriarty

mayurs said:


> It's here, the TA-26 and first impressions are extremely positive. Love it with my HD600 and R70X which absolutely demand an OTL and frankly  are pretty much nonsense with most SS amps I have tried. The TA-26 is not the most resolving amp, atleast with the stock tubes, but then it's still very new and hardly burnt in. One thing that really stands out is the headspace. It even expands the relatively closed HD600 out of my head in all directions. I even tried the pre amp function to my SS Headphone amp and it was again mighty impressive driving my ER4XRs,  which sounded the best ever on my SS amp. I plan to stick with the stock tubes to fully run in the amp and then bring out my better tubes once it is ready.


Nice! I'm on the same boat, I'll use the stock tubes for a while, make sure they are burned in then roll them. I don't have much experience rollings tubes so I don't know what I prefer. Got a military grey glass RCA 6SN7GT or VT231 with an RCA 6AS7G from Brent at Audiotubes, waiting for them to ship but I'm in no hurry. Even with the stock tubes, the experience is very enjoyable.


----------



## jonathan c

mformoriarty said:


> Nice! I'm on the same boat, I'll use the stock tubes for a while, make sure they are burned in then roll them. I don't have much experience rollings tubes so I don't know what I prefer. Got a military grey glass RCA 6SN7GT or VT231 with an RCA 6AS7G from Brent at Audiotubes, waiting for them to ship but I'm in no hurry. Even with the stock tubes, the experience is very enjoyable.


…it will get _a lot more_ enjoyable with the RCA ‘munitions’…👍


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## mayurs

Anyway couldn't resist a tube swap and swapped the power tube to a Chatham 6080WA. The immediate improvement seen is the reduced the mid bass bloat. THE 608O tube sits deep down inside the chassis but I am finding this amp to be a lot cooler running than my Feliks Eufora running 4 tubes.


----------



## jonathan c

dsrk said:


> I am doing the same with my low impedance headphones pre amp to Topping NX7.
> 
> TA-26 is my first OTL. HD6XX on TA-26 is the best I heard it sound.


HD6XX, at 300 ohms, will always sound its best with a high output impedance OTL ☑️.


----------



## dsrk

jonathan c said:


> HD6XX, at 300 ohms, will always sound its best with a high output impedance OTL ☑️.


Yes, I heard that so many times but experienced it very recently. I have owned HD650/6XX for more than a decade and bought OTL just a few months ago. I can't believe how I ignored it all those years. 
it's because I spend very less time on my desktop listening to music. I am a portable user and invested mostly on DAPs and portable DAC/AMPs. I am really excited to try the upcoming XD-05 Pro.


----------



## hbmorrison

Just got this NOS Mullard 6080 for my TA-26. I'm still letting it cook for a bit but from what I have heard the bass is more substantial and extended on my HD6xx and DT770Pros.


----------



## jonathan c

hbmorrison said:


> Just got this NOS Mullard 6080 for my TA-26. I'm still letting it cook for a bit but from what I have heard the bass is more substantial and extended on my HD6xx and DT770Pros.


What tube are you using with the Mullard 6080?


----------



## hbmorrison

jonathan c said:


> What tube are you using with the Mullard 6080?



Just the bog standard one that came with the TA-26 for now. Probably a JJ? Got my eye on a couple of NOS Sylvanias for next month though.


----------



## jonathan c

hbmorrison said:


> Just the bog standard one that came with the TA-26 for now. Probably a JJ? Got my eye on a couple of NOS Sylvanias for next month though.


(PM)


----------



## Ufanco

LowBeat91 said:


> Is there a balanced tube pre amp from Xduoo?


There’s the xDuoo TA20 and xDuoo MT604 I have the TA20 and enjoy the sound quality it produces. There a lot of tube rolling option with the TA20 if into tube rolling. Don’t know much about the MT604.


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## mformoriarty

New tubes for the TA-26 just arrived. Giving the stock tubes another listen for an hour before swapping them. It's gonna be a good weekend.


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## mformoriarty (Oct 2, 2022)

Couldn't wait to try the new tubes. Interesting first boot up. You can see the electron flux crashing against the glass on the power tube.


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## mayurs

I think I have found the tubes that I will stick to on my TA26. Raytheon flat plates VT231 and the Chatham 6080WA. The Raytheons are extremely clear in the mid range which kind of helps the amplifier as it's a little low in resolution compared to some more expensive tube amps that I have heard along with the Chatham powers that tighten the bass and have extended treble compared to the stock power tube. I think with the right tubes this amp can really sound quite good and has great synergy with the HD600 and R70X.


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## mayurs

OK! So I found that the TA-26 sounds even better with a Tungsol 6SN7GT black glass round plates vs any other driver I have tried. But the only problem is that this is now a very very expensive tube that probably costs as much or maybe more than the amp itself. But those who have this tube please try it and see how much better the TA-26 is able to deliver with this tube driving it.


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## hbmorrison

I have never been one for cable-fi and the more esoteric side of power management, but my TA-26 had a transformer buzz that I had been ignoring until now.

On a whim, I decided to get an ifi DC blocker.





I'm not really sure why. But colour me surprised it has reduced the buzz almost to nothing and I think the dynamics have been tightened up a bit too?

I dunno I am still extremely skeptical but I suppose power conditioning does at least have a decent argument behind it.

I'm kind of tempted to get an AmpRX EuroVolt now. 🙄


----------



## roderickvd

DC blocking is a real thing and not so esoteric (I'm not one for cable fanfare either, for example). Most households don't have such a high DC offset that transformers hum, but if you do then this may well fix it.


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## greenblured

I had no buzz, but added an Ifi DC blocker to my Feliks Echo. Improved dynamics and a cleaner sound. The transforner on the amp is noticeably cooler. It's like the amp is operating more effordlessly. Well worth the money ime.


----------



## g0ldl10n

Silver Wolf said:


> Oh and a better pic of the tubes I'm currently listening to for those into them. NOS Melz 1578 + MWT/GEC 6080/A1834 stubby, maybe I should get a riser for at least the back, looks funny being lower to me (Feng Shui 'n all) but then I prefer the look of ST style tubes.


Hey, thanks a lot for those measurements!


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## hbmorrison

Speaking of risers, will an 8-pin 6sn7 socket saver work for the 6as7 socket? I think physically the sockets are the same but not certain.


----------



## HardstyleLoco96 (Oct 25, 2022)

Hello I am considering getting myself a Xudoo TA-26. And was wondering what you guys think are some good tubes for it. I don't want to spend more than $200 Aud. 😊


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## sonicm (Oct 25, 2022)

I'm back in the audiophile scene after a loooong hiatus. I'm considering the TA-30 as my first tube amp, but I'm worried it isn't 'tube-y' enough. I want the full tube amp experience, can the ta-30 provide that? Part of the reason I'm picking it is because I don't have a DAC. But I could also get a $200 DAC and a TA-26. I'm noticing the ta-30 isn't very popular but the ta-26 is decently popular for some reason I haven't figured out just yet.


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## mayurs

sonicm said:


> I'm back in the audiophile scene after a loooong hiatus. I'm considering the TA-30 as my first tube amp, but I'm worried it isn't 'tube-y' enough. I want the full tube amp experience, can the ta-30 provide that? Part of the reason I'm picking it is because I don't have a DAC. But I could also get a $200 DAC and a TA-26. I'm noticing the ta-30 isn't very popular but the ta-26 is decently popular for some reason I haven't figured out just yet.


The TA-26 is a proper tube OTL amp with a driver and power tube while most other are hybrids which make a difference in sound quality if you are specifically chasing a 'tube' sound. The TA-26 is popular as it drives most high impedance Senn, Beyer, AT hps which sound really good out of OTLs vs SS and Hybrid amps.


----------



## roderickvd

I had the TA-20 and didn’t think it sounded very tubey. I second the advice to go for an OTL.


----------



## dsrk

sonicm said:


> I'm back in the audiophile scene after a loooong hiatus. I'm considering the TA-30 as my first tube amp, but I'm worried it isn't 'tube-y' enough. I want the full tube amp experience, can the ta-30 provide that? Part of the reason I'm picking it is because I don't have a DAC. But I could also get a $200 DAC and a TA-26. I'm noticing the ta-30 isn't very popular but the ta-26 is decently popular for some reason I haven't figured out just yet.


It depends on what exactly you are after. Hybrids are not that warm and smooth like an OTL. 
TA-26 is pure OTL which works well with high impedance headphones but not so much with low impedance headphones especially planars. 

I see you have the Beyer and Grados too, it definitely sounds great with the Beyer but it may not be that great with the grados.


----------



## -Darkstar-

sonicm said:


> I'm back in the audiophile scene after a loooong hiatus. I'm considering the TA-30 as my first tube amp, but I'm worried it isn't 'tube-y' enough. I want the full tube amp experience, can the ta-30 provide that? Part of the reason I'm picking it is because I don't have a DAC. But I could also get a $200 DAC and a TA-26. I'm noticing the ta-30 isn't very popular but the ta-26 is decently popular for some reason I haven't figured out just yet.


I have a TA-30 and I enjoy it, but it doesn't sound like my all-tube Valhalla or HP8Mk2. It doesn't have the midrange bloom those two have but the bass has more impact. If you are looking for an all in one, you might consider a 2nd gen Woo Audio WA7. It was one of the amps I was considering before going with the TA-30.


----------



## sonicm

@roderickvd @dsrk @mayurs 
Ahh that makes sense. I definitely want that classic tube sound, I want the full experience with this amp so I'm gonna want a OTL. After days of research and comparing, I decided to go with the Ta-26, as its got the best price and rating at this level. I'm still not sure about tubes yet, I guess researching that will take the rest of the week lol


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## sonicm (Oct 26, 2022)

-Darkstar- said:


> I have a TA-30 and I enjoy it, but it doesn't sound like my all-tube Valhalla or HP8Mk2. It doesn't have the midrange bloom those two have but the bass has more impact. If you are looking for an all in one, you might consider a 2nd gen Woo Audio WA7. It was one of the amps I was considering before going with the TA-30.


How do you like your Valhalla? I was highly considering that one, but what turned me off was the description on their website that says "_If you’re expecting syrupy, tubby, euphonically colored tube sound, you’re in for a shock. Valhalla 2 is exceptionally accurate, neutral, and resolving, without being strident or etched_". I wanna go all in with my first tube amp so 'exceptionally accurate' isn't what I'm looking for. I want warm and euphonic. What's your feel on the amp?

I was actually looking at the WA7 just yesterday, it is indeed a beautiful piece but I decided to go with a separate DAC(Schiit Modius) and amp(probably ta-26).


----------



## -Darkstar-

sonicm said:


> How do you like your Valhalla? I was highly considering that one, but what turned me off was the description on their website that says "_If you’re expecting syrupy, tubby, euphonically colored tube sound, you’re in for a shock. Valhalla 2 is exceptionally accurate, neutral, and resolving, without being strident or etched_". I wanna go all in with my first tube amp so 'exceptionally accurate' isn't what I'm looking for. I want warm and euphonic. What's your feel on the amp?
> 
> I was actually looking at the WA7 just yesterday, it is indeed a beautiful piece but I decided to go with a separate DAC(Schiit Modius) and amp(probably ta-26).


I think the Valhalla is a very good amp for its price point. It isn't overly euphonic or rolled off in the highs, but it isn't bright at all, even with my Beyers. I think it's great at all kinds of music, not just slower tempo stuff. I have the original version of the Valhalla; the newer version is supposed to be better with lower impedance cans but it's still an OTL and not ideal.  Good luck with the TA-26.


----------



## Nicolas from France

Anyone tried the Xduoo MT-604 with Focal Clear and Hifiman Sundara? Would you recommend it?
​


----------



## ClicketEKlack

Nicolas from France said:


> Anyone tried the Xduoo MT-604 with Focal Clear and Hifiman Sundara? Would you recommend it?
> ​


I use it with Focal Utopias and the sound is excellent rich, detailed, and smooth -- the only caveat is that you really need a pre-amp to control the volume. The power is insane.


----------



## Nicolas from France

ClicketEKlack said:


> I use it with Focal Utopias and the sound is excellent rich, detailed, and smooth -- the only caveat is that you really need a pre-amp to control the volume. The power is insane.


What pre-amp are you or would you use?


----------



## ClicketEKlack

Nicolas from France said:


> What pre-amp are you or would you use?


I use an OG Topping A90. You can use anything with balanced XLR in/out and a volume knob (that way you can set the MT-604's two knobs to one ideal position and never touch them again). Transparency in the amp would likely be an ideal trait, as you want the cleanest signal from the DAC and then use the MT-604's tubes to color the sound, rather than the pre-amp.


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## roderickvd (Oct 29, 2022)

I am considering getting a TA-26 but dislike the red knob. Does anyone have suggestions to replace the knob?

The other OTL that I am considering is a Felix Audio Echo 2 at more than twice the price. Aesthetics aside I am not sure if it will be twice as good. It even has worse THD and power. But maybe its capacitors can be rolled?

Suggestions welcome. I will be pairing with high-Z Beyers, a 250 ohm Amiron Home and 600 ohm T1.2.


----------



## Nicolas from France

ClicketEKlack said:


> I use an OG Topping A90. You can use anything with balanced XLR in/out and a volume knob (that way you can set the MT-604's two knobs to one ideal position and never touch them again). Transparency in the amp would likely be an ideal trait, as you want the cleanest signal from the DAC and then use the MT-604's tubes to color the sound, rather than the pre-amp.


Thanks. Would this do as pre amp ??: https://www.audiophonics.fr/en/dac-...2-spdif-dac-pcm1793-24bit-192khz-p-16738.html.


----------



## mayurs

roderickvd said:


> I am considering getting a TA-26 but dislike the red knob. Does anyone have suggestions to replace the knob?
> 
> The other OTL that I am considering is a Felix Audio Echo 2 at more than twice the price. Aesthetics aside I am not sure if it will be twice as good. It even has worse THD and power. But maybe its capacitors can be rolled?
> 
> Suggestions welcome. I will be pairing with high-Z Beyers, a 250 ohm Amiron Home and 600 ohm T1.2.


Rolling tubes imo is a very important consideration while choosing a tube amp. Those feliks audio amps sure do sound good but just check how easy is to roll those tubes on the new Echo coz I remember it wasn't so easy or plentiful as what is possible with the Xduoo TA-26. Sound wise I don't think there will be much to choose between.


----------



## ClicketEKlack

Nicolas from France said:


> Thanks. Would this do as pre amp ??: https://www.audiophonics.fr/en/dac-...2-spdif-dac-pcm1793-24bit-192khz-p-16738.html.


No, it’s a DAC, and it’s not balanced. Do you also need a DAC? If so, the Topping D30 Pro is a balanced DAC that can be used as a pre-amp.


----------



## Knobstler

Can someone please recommend tubes for the xduoo ta-20?


----------



## Ufanco (Oct 30, 2022)

Knobstler said:


> Can someone please recommend tubes for the xduoo ta-20?



Here’s the tubes I use with the TA20. Last row is my ratings.


RCA/Conn12AU7aGray PlateSide Getter****Northern Electric12AU7Black PlateCircle***Amperex12AU7/ECC82Gray PlateCircle****Pinnacle13D5AGray PlateCircle****Westinghouse/Conn12AU7Ribbed Black PlateSquare double bar***Sylvania12BH7aBlack PlateSquare double bar*****CBS12BH7aShort black plateSquare bar***+CBS?/Crosley12BH7Short black plateHorizon bent sq****RCA12BH7aLong Gray PlateThick Circle*****Hytron12BH7Short black plateCircle*****Sylvania12bh7aShort gray plateSquare double split bar****Westinghouse12bh7Short black plateD double bars***+


----------



## Knobstler

Ufanco said:


> Here’s the tubes I use with the TA20. Last row is my ratings.
> 
> 
> RCA/Conn12AU7aGray PlateSide Getter****Northern Electric12AU7Black PlateCircle***Amperex12AU7/ECC82Gray PlateCircle****Pinnacle13D5AGray PlateCircle****Westinghouse/Conn12AU7Ribbed Black PlateSquare double bar***Sylvania12BH7aBlack PlateSquare double bar*****CBS12BH7aShort black plateSquare bar***+CBS?/Crosley12BH7Short black plateHorizon bent sq****RCA12BH7aLong Gray PlateThick Circle*****Hytron12BH7Short black plateCircle*****Sylvania12bh7aShort gray plateSquare double split bar****Westinghouse12bh7Short black plateD double bars***+


Thanks now i need to find a dealer


----------



## Ufanco

Knobstler said:


> Thanks now i need to find a dealer


I tend to like the 12bh7 tubes better than 12au7 (only 12bh7 I didn't like where a pair the GE tubes). Not sure who to recommend as a good tube dealer in you country. I bought some on eBay and some here on head fi. Here is a link reviewing some 12au7 and equivalent tubes.
https://www.head-fi.org/threads/12a...-comment-on-your-12au7-or-equivalents.962449/


----------



## Halimj7

What is the tubiest sounding dac/amp that xduoo makes? Looking for something that’s works on iems and easier to drive headphones. I don’t need a lot of power. Thanks


----------



## kibot

Hi guys!

Does sombody know something about this pretty guy?? (Xduoo TA 22)


----------



## Knobstler

Would i be able to connect the aux out of the ta 20 to my ayima amp to power bass transducers while listening to through the headphones?


----------



## alterndog

The TA-03s is on sale at Drop for $140. Seems to be the cheaper price ever.


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## Ufanco (Nov 11, 2022)

Knobstler said:


> Would i be able to connect the aux out of the ta 20 to my ayima amp to power bass transducers while listening to through the headphones?


The rca out bypassed the amp/tube section. You be able to use headphone with it. It's a fixed output so volume control doesn't work on the ta20 on the rca out, you have to use the ayima amp to control volume to the bass transducers.


----------



## Knobstler

Ufanco said:


> The rca out bypassed the amp/tube section. You be able to use headphone with it. It's a fixed output so volume control doesn't work on the ta20 on the rca out, you have to use the ayima amp to control volume to the bass transducers.


Ok but in theory that will work?


----------



## Ufanco

Knobstler said:


> Ok but in theory that will work?


Yes it would work. If looking for a used TA20 let me know I just upgraded my tube amp and thinking of selling mine. PM me if interested.


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## Knobstler

Ufanco said:


> Yes it would work. If looking for a used TA20 let me know I just upgraded my tube amp and thinking of selling mine. PM me if interested.


Thank you! But i already bought one.


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## karloil (Nov 14, 2022)

Just joined the Xduoo family!

Got my TA-26 last week - 1st time trying out tubes and I want to see (well hear) what the fuzz is all about pairing HD60X cans with tubes.

Now I understand...currently pairing with my RS2 and overall tonalty is smooth and warm. Bossa Nova never sounded this good! 😍


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## Silver Wolf (Nov 17, 2022)

Enjoying an all Philips Miniwatt (Heerlen) tube set run currently in my TA-30, Matched pair of E182CC SQ and a 5U4G
(E182CC to 12BH7 converters used). Very nice.... I like them even more maybe than my other 12BH7 tubes, also for those interested I tried them in my TA-20 and they work but on first power up from dead cold the TA-20 throws protect sometimes, but same happens with some other tubes (12BH7 and one pair of 12AT7) on my TA-20.






Also got that socket saver/tube riser for the MWT/Osram 6080/A1834 so it looks better, a more authoritative height now in the TA-26 giggle


----------



## Knobstler

Ufanco said:


> The rca out bypassed the amp/tube section. You be able to use headphone with it. It's a fixed output so volume control doesn't work on the ta20 on the rca out, you have to use the ayima amp to control volume to the bass transducers.


I tried it and it works but the input aignal seems to strong. And the transducers even react to voices. Is there a fix? It works alot better from the sub out of my marantz avr


----------



## dstarr3

Does anyone have a TA26 that they use a preamp on a solid state amp to drive low-impedance headphones? I already have a Liquid Platinum amp, which is a great way to tube up some sensitive headphones, but I'm interested in exploring other options.

So, using the TA26 as a preamp, does anyone have any experience with this? Is it good?


----------



## dsrk (Nov 21, 2022)

dstarr3 said:


> Does anyone have a TA26 that they use a preamp on a solid state amp to drive low-impedance headphones? I already have a Liquid Platinum amp, which is a great way to tube up some sensitive headphones, but I'm interested in exploring other options.
> 
> So, using the TA26 as a preamp, does anyone have any experience with this? Is it good?


I am using one but a portable AMP (Topping NX7) for my LCD2C and it sounds so better than straight out of TA-26.

My other low impedance headphones (KPH40 and FD7) sound great straight out of TA-26.


----------



## Ufanco (Nov 22, 2022)

Knobstler said:


> I tried it and it works but the input aignal seems to strong. And the transducers even react to voices. Is there a fix? It works alot better from the sub out of my marantz avr


Something like this might work. There are more expensive options but would try something like this first.

https://www.amazon.com/Amplifier-Audio-Subwoofer-Equalizer-Controller/dp/B07D6JTD4V/ref=sr_1_6?crid=1U81X9X6RI1WO&keywords=rca+volume+control+for+subwoofer&qid=1669144073&sprefix=rca+volume+control+for+subwoofer+,aps,73&sr=8-6


----------



## Knobstler

Ufanco said:


> Something like this might work. There are more expensive options but would try something this first.
> 
> https://www.amazon.com/Amplifier-Audio-Subwoofer-Equalizer-Controller/dp/B07D6JTD4V/ref=sr_1_6?crid=1U81X9X6RI1WO&keywords=rca+volume+control+for+subwoofer&qid=1669144073&sprefix=rca+volume+control+for+subwoofer+,aps,73&sr=8-6


Thank you im going to try a y subwoffer cable first instead of rca to rca. You think that might help? The ayima has already a sub frequencie tone control


----------



## Ufanco

Knobstler said:


> Thank you im going to try a y subwoffer cable first instead of rca to rca. You think that might help? The ayima has already a sub frequencie tone control



Good ideal on trying the splitter if amp already has sub out it should work fine. Sorry I forgot your using an amp along side the tube amp.
Just to be clear your running source into the Xduoo ta20 then using the rca output on the ta20 to send signal to a the ayima amp that’s powering the butt shakers. The ayima has a subwoofer output that allows to cut out high frequencies and you just want to run the signal into the butt shakers ?
Has me wondering if you used 1/4 to rca if it allow use of volume on the TA20 to control the volume and save having to use 2 volume controls. Not sure it this would work but it would allow an easier way to control volume.

https://www.amazon.com/TISINO-Gold-...r=J4GJNB74M2J21BNYWV5T&qid=1669146696&sr=8-20


----------



## Knobstler (Nov 22, 2022)

Ufanco said:


> Good ideal on trying the splitter if amp already has sub out it should work fine. Sorry I forgot your using an amp along side the tube amp.
> Just to be clear your running source into the Xduoo ta20 then using the rca output on the ta20 to send signal to a the ayima amp that’s powering the butt shakers. The ayima has a subwoofer output that allows to cut out high frequencies and you just want to run the signal into the butt shakers ?
> Has me wondering if you used 1/4 to rca if it allow use of volume on the TA20 to control the volume and save having to use 2 volume controls. Not sure it this would work but it would allow an easier way to control volume.
> 
> https://www.amazon.com/TISINO-Gold-Plated-6-35mm-Stereo-Splitter/dp/B07HFBWP87/ref=sr_1_20?content-id=amzn1.sym.01541a8b-0ce9-4a81-bd03-b7198aa37c61:amzn1.sym.01541a8b-0ce9-4a81-bd03-b7198aa37c61&keywords=1/4+to+rca&pd_rd_r=7b07f387-8129-44b4-ba19-31bf096f9ba5&pd_rd_w=hYgcr&pd_rd_wg=7XGIT&pf_rd_p=01541a8b-0ce9-4a81-bd03-b7198aa37c61&pf_rd_r=J4GJNB74M2J21BNYWV5T&qid=1669146696&sr=8-20


I was wondering the same before but. But the 1/4 inch is probably gonna have a different impedance then the rca outs. The problem going from the rca out on ta20 into the rca in on the ayima is way to sensitive. Also i still want to be able to power my aryas from xlr to full potential


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## kibot (Nov 23, 2022)

Pяivet guys!
So im add HD 650 to my cans family and what can i said:
HD 650 sounds more agressive but with little warm with more power in bass and treble
and
HD 600 sounds calm and very waaarm in comparison with HD 650 (with TA 26 its nice for industrial, noice and ect similar bad recorded genres)


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## Ufanco

kibot said:


> Pяivet guys!
> So im add HD 650 to my cans family and what can i said:
> HD 650 sounds more agressive but with little warm with more power in bass and treble
> and
> HD 600 sounds calm and very waaarm in comparison with HD 650 (with TA 26 its nice for industrial, noice and ect similar bad recorded genres)


Love the wall treatment On the HD650 you might have to tube roll to find one the works better with the HD650. Being there a popular headphone hopefully someone can chime in on tubes they liked with the TA26. Below is a link to tube rolling for the TA26.

https://audiofool.reviews/tube-rolling-the-xduoo-ta-26/


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## kibot

Ufanco said:


> Love the wall treatment On the HD650 you might have to tube roll to find one the works better with the HD650. Being there a popular headphone hopefully someone can chime in on tubes they liked with the TA26. Below is a link to tube rolling for the TA26.
> 
> https://audiofool.reviews/tube-rolling-the-xduoo-ta-26/


Great thanks for advice - i like moooore warm tube))....but this two "guys"(Hd 650 and 600) are best and universal TA-26 pairing(i compare with those cans that i have such as Takstar HF 580 and DT 770 pro 250 Ohm)


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## mayurs (Nov 27, 2022)

XDuoo TA-26 is getting most use on my rig as it has transformed all my HPs to amazing sounding ones. (I have built my system around high impedance Senns and ATs.)

The biggest change in sound comes from changing the driver tubes. Having tried all my 6SN7 tubes (Raytheon, Ken Rad, Sylvania, RCA, NU VT231s and many others) I have found that the Tungsol 6SN7GT black glass round plates (BGRP),  completely transforms this amp to a much higher performing one than the one with stock tubes. The R70x and HD600 are probably at the peak of what they can sound with the BGRP and Tungsol 6080. I think I have to get rid of my SS desktop amp after this as it's getting hardly any ear time, such has been the performance gain since shifting to the TA-26 for my specific cans.

Yes that BGRP probably costs as much as the TA-26 or even more, but I would say that this is a must try tube on the TA-26. It has a similar performance improvement on my Euforia as well. Definitely a highly recommended 6SN7, if you can find one and no wonder they are all mostly gone and come up on sale at ridiculous prices every now and then.  These tubes also come up as rebrands that cost significantly less so am attaching a photo that gives the top structure of the 2 types of BGRP that exist so that you know what you are actually getting.


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## karloil (Dec 4, 2022)

Hi everyone, I want to get your opinon, still new to tubes and now would like to start tube rolling.

For those who use/of have used tube socket savers - need to clarify, get your opinion regarding them.

From my understanding, these 2 does the trick:


But this guy also caught my attention and it looks like it's the socket that gets soldered to the PCB but also looks like a low profile socket saver:


I have 2 questions:
1. Which of these do you find best to use?
2. Can the 3rd photo (the bottom one) - also act as a socket saver? Or is this only used on PCBs?

*EDIT:*

After much reading/viewing - I think I answered my own question and went with these instead:


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## borkenarrou

Are there better tubes for the MT-604 than the default ones, I am new into the tube world, only have experience with the little bear b4x.


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## rmkjr

borkenarrou said:


> Are there better tubes for the MT-604 than the default ones, I am new into the tube world, only have experience with the little bear b4x.


I've been enjoying these: https://www.amazon.com/gp/product/B089GQK6GD/

A bit less harsh and more full than stock.  They didn't have matched quads on Amazon, so I just bought 2 pairs, and then put 1 from each pair in each channel in the amp (basically every other left to right) to avoid any channel imbalance.


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## matp86

Was hoping to get some help here regarding a strange issue on my TA-30.
One of the orange LED’s beneath the left pre-amp tube turns off shortly after powering on. If the tubes are removed the LED remains on. Switching tubes around does not move the issue- it always turns off on the left side. Sound is fine. Has anyone experienced such an issue?


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## ClicketEKlack

borkenarrou said:


> Are there better tubes for the MT-604 than the default ones, I am new into the tube world, only have experience with the little bear b4x.


These are probably equivalent to the Fosi: 
https://www.amazon.com/gp/product/B09CMQ8MV6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I've been really enjoying the sound.


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## ColSaulTigh

matp86 said:


> Was hoping to get some help here regarding a strange issue on my TA-30.
> One of the orange LED’s beneath the left pre-amp tube turns off shortly after powering on. If the tubes are removed the LED remains on. Switching tubes around does not move the issue- it always turns off on the left side. Sound is fine. Has anyone experienced such an issue?


No, mine stay lit constantly.  Might want to contact customer service.


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## karloil

Reinforcements have arrived!  

Will give it a good burn in and give impressions later on.


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## ducnsh

rmkjr said:


> I've been enjoying these: https://www.amazon.com/gp/product/B089GQK6GD/
> 
> A bit less harsh and more full than stock.  They didn't have matched quads on Amazon, so I just bought 2 pairs, and then put 1 from each pair in each channel in the amp (basically every other left to right) to avoid any channel imbalance.


You bought 2 pairs (4 tubes) but you used only 2 tubes, for each channel?


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## rmkjr

ducnsh said:


> You bought 2 pairs (4 tubes) but you used only 2 tubes, for each channel?


Bought 2 pairs.  Then in each channel I put 1 tube from each pair (so 2 tubes in each channel, but so they are mixed between the purchased pairs).  When I put a whole matched pair into each channel, I noticed a level mismatch between left and right.  When I mixed the pairs together, that went away.  Probably not as ideal as a matched quad, but it has been working well since.


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## ducnsh

rmkjr said:


> Bought 2 pairs.  Then in each channel I put 1 tube from each pair (so 2 tubes in each channel, but so they are mixed between the purchased pairs).  When I put a whole matched pair into each channel, I noticed a level mismatch between left and right.  When I mixed the pairs together, that went away.  Probably not as ideal as a matched quad, but it has been working well since.


Thanks for the explanation, are these tubes tall as the stocks?


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## rmkjr

ducnsh said:


> Thanks for the explanation, are these tubes tall as the stocks?


Yep yep, they look exactly the same dimension-wise


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## CADCAM

I have the Xduoo MT-602 and just saw the Xduoo MU-602 DAC, can anyone point me in the right direction to get any info on this? Can't find anything...


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## Winter Sky

I have ta-20 What tubes are suitable for acoustic,vocals songs?


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## S Crowther

Winter Sky said:


> I have ta-20 What tubes are suitable for acoustic,vocals songs?


Amperex bugle boy


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## Just85

Winter Sky said:


> I have ta-20 What tubes are suitable for acoustic,vocals songs?


I have just bought Psvane 12au7-S tubes, the vocals come forward with these tubes, so I think they would be suitable for that kind of music.


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## Just85

Hey guys, just wanted to ask about socket savers, since they are quite recessed, how do you remove them? I am hesitating to buy ones.


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## Winter Sky

S Crowther said:


> Amperex bugle boy


Thank You but The price is too high for me.


Just85 said:


> I have just bought Psvane 12au7-S tubes, the vocals come forward with these tubes, so I think they would be suitable for that kind of musicThan


Thank for detail, Have you listened to jj ecc802s?


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## Just85

Winter Sky said:


> Thank You but The price is too high for me.
> 
> Thank for detail, Have you listened to jj ecc802s?


No, I haven't. I have read that they should be warm and bassy, but not on par with tubes that cost twice as much. I am thinking about 12at7 tubes and maybe I will try JJ's here.


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## Ufanco (Sunday at 3:13 PM)

@Winter Sky 

The TA 20 can use 12bh7/12bh7a tubes I find they sound incredible and don’t cost a fortune. Just be aware they run a little hotter so occasionally it will tigger fault protection  (just turn it off and turn it back on usually fix’s the problem)

Being a larger tube the tube protecter won’t fit but felt the benefits outweighs the disadvantages. If want to stick with 12au7 the RCA cleartop is a good choice.

How much is you’re budget?

https://audiofool.reviews/tube-rolling-the-xduoo-ta-01b-ta-10-and-ta-20-12au7-amps/


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## CADCAM (Yesterday at 9:10 AM)

I accidently left my MT-602 on after a quick listening session and came back into the room to shut some shades for the night and noticed it on as well as my SMSL SU-8 DAC.
Couldn't help a quick listen and was surprised to hear better more defined bass and overall it honestly seemed to sound better than ever!
It certainly seems like leaving it on for 7 to 8 hours did some good toward an overall improvement in SQ. I don't think I'm comfortable leaving the tubes on all that time in standby mode but I will increase my warmup time on this amp to maybe an hour before I start listening.
I'm still listening...


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## Just85

I have had TA-20 amp for several weeks now and I am using it with Meze 99 Noir and Audeze LCD-2C headphones. I absolutely love it with 99 Noir, however it feels underwhelming with LCD-2C. Is anyone using this amp with Audeze heapdhones? I am using the TA-20 with Psvane Art 12AU7-S tubes.


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## vmiguel

Don't ask me for technical details, but tube amps and planar headphones are normally not a good match.


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## jonathan c (Thursday at 3:50 PM)

Just85 said:


> I have had TA-20 amp for several weeks now and I am using it with Meze 99 Noir and Audeze LCD-2C headphones. I absolutely love it with 99 Noir, however it feels underwhelming with LCD-2C. Is anyone using this amp with Audeze heapdhones? I am using the TA-20 with Psvane Art 12AU7-S tubes.


What is ‘underwhelming’ about what you hear via LCD-2C? The TA-20 is a hybrid h/p/a: the 12AU7 tubes are in the preamp stage and transistors are in the output stage. The maximum output @ 32 ohms for TA-20 is 2000 mw; the recommended level for LCD-2C is 250 mw. OK, there! So …. possibly a change of tubes? …. 🤷🏻‍♂️


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## ColSaulTigh

vmiguel said:


> Don't ask me for technical details, but tube amps and planar headphones are normally not a good match.


This statement is not correct.

OTL Tube amps are not the best match for Planars, but hybrids, and SET tubes amps work just fine...


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## Just85

vmiguel said:


> Don't ask me for technical details, but tube amps and planar headphones are normally not a good match.


Yeah, but this one is hybrid, so I thought that does not apply.


jonathan c said:


> What is ‘underwhelming’ about what you hear via LCD-2C? The TA-20 is a hybrid h/p/a: the 12AU7 tubes are in the preamp stage and transistors are in the output stage. The maximum output @ 32 ohms for TA-20 is 2000 mw; the recommended level for LCD-2C is 250 mw. OK, there! So …. possibly a change of tubes? …. 🤷🏻‍♂️


It should definitely have enough power. Well, I am missing the energy, the kick, the dynamics. Maybe those things will improve with brighter tubes.


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## vmiguel

Yes, I stand corrected 🙂
It's the OTL ones. And yes, the TA-20 is a hybrid and on paper seems to be able to drive the phones.


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## Ieonasj (Yesterday at 4:04 AM)

im new in audio. what  economy from Xduoo best for my audeze lcd-2c, if im no listen DSP,DSD files,only streaming from tidal,mqa, or mp3,flac,cd, files from laptop?better buy tube,transistor or hybrid amp/dac. Im need DAC or AMP only,or dac/amp? im need amp with 6.35mm only  or better balanced 4.4 output? lcd-2c has 70ohm 101db sensivity. Does i can see to TA-03 is good for me in 2023year, or better look to ta20,22,26,30? or any other


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## Just85

Ieonasj said:


> im new in audio. what  economy from Xduoo best for my audeze lcd-2c, if im no listen DSP,DSD files,only streaming from tidal,mqa, or mp3,flac,cd, files from laptop?better buy tube,transistor or hybrid amp/dac. Im need DAC or AMP only,or dac/amp? im need amp with 6.35mm only  or better balanced 4.4 output? lcd-2c has 70ohm 101db sensivity. Does i can see to TA-03 is good for me in 2023year, or better look to ta20,22,26,30? or any other


Do you already have LCD-2C? I am not sure that I understand correctly, but if your speaking about value, I would look for TA-10. It has a built in DAC, XLR output and this review says it is good for planars like LCD-2C:
https://headfonics.com/xduoo-ta-10-review/

DEFINITELY do not skip on DAC. Audeze LCD-2C are too good to be used without a DAC and you will notice the difference. 

Also, you can send me a PM.

Galima ir lietuviškai


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## Ieonasj (Yesterday at 5:30 AM)

Just85 said:


> Do you already have LCD-2C? I am not sure that I understand correctly, but if your speaking about value, I would look for TA-10. It has a built in DAC, XLR output and this review says it is good for planars like LCD-2C:
> https://headfonics.com/xduoo-ta-10-review/
> 
> DEFINITELY do not skip on DAC. Audeze LCD-2C are too good to be used without a DAC and you will notice the difference.
> ...


siaip pas mane LCD-2C Closed. kuo skiriasi DAC nuo AMP. amp ,aisku stiprintuvas. o kam reikalingas dac? dac keicia audio signala i analogini ir atvirksciai? man turbut nereikia jokio dac jei per usb-c,ar 3.5 ausiniu isejima jungiu stprintuva?audeze turi 6.35mm jungti. tai man reikia lempinio stiprintuvo su 6.35 jungtimi ar geriau pirkti xlr laida ir jungi prie stiprintuvo su xlr jungtimi? ar naudoti perejima 6.35 to 3.5. garso kokybe is balanced geriau nei per 6.35? ar ta pati? ir  geriau pirkti lempini ar normalu tranzistorini stiprintuva? lempinius reikia dauzyti gal veiktu geriau ir karsti labai ir energijos ryja daug.


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## Just85

Ieonasj said:


> siaip pas mane LCD-2C Closed. kuo skiriasi DAC nuo AMP. amp ,aisku stiprintuvas. o kam reikalingas dac? dac keicia audio signala i analogini ir atvirksciai? man turbut nereikia jokio dac jei per usb-c,ar 3.5 ausiniu isejima jungiu stprintuva?audeze turi 6.35mm jungti. tai man reikia lempinio stiprintuvo su 6.35 jungtimi ar geriau pirkti xlr laida ir jungi prie stiprintuvo su xlr jungtimi? ar naudoti perejima 6.35 to 3.5. garso kokybe is balanced geriau nei per 6.35? ar ta pati? ir  geriau pirkti lempini ar normalu tranzistorini stiprintuva? lempinius reikia dauzyti gal veiktu geriau ir karsti labai ir energijos ryja daug.


I'll send you a private message to keep this thread in English.


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## Ieonasj

im found only one can decode MQA files from xduoo ,list is
xDuoo TA-22​


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