# Elekit 300B Amp kit



## SuperDuke

I had a chance to briefly hear this amp w/ open baffle speakers at Capital Audio Fest last year and was intrigued. 




http://www.vkmusic.ca/TU-8600.htm

Has anyone built it?  Impressions?  Here is the only review I have found:

http://wallofsound.ca/uncategorized/quick-update-on-our-most-anticipated-new-amp-of-2017-review/


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## HiGHFLYiN9

Really hard to say. I've heard great things and mixed things about the Elekit units. Never tried one myself, but I would hope it would sound excellent for this price. $2400 with the Lundahls is a little pricey to roll the dice, at least for my wallet 

Now $700 on the other hand...


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## ForSure

I finished mine 8600 2 weeks ago with about 40 hours running time now.  I have to say it is the best sounding amp IF you are listening to DSD or clean vinyl.  This amp will pickup all little details in the music.  However, with the vkmusic upgrade part, this will be a overkill as  a dedicated headphone amp.  Lately, I have been using my HD6XX with 8200dx with the golden lion ecc82 and EH-K88 and found that it is a good match, a lot more musical than the Grace design m9XX.  I will be using the ekekit 8600 as home stereo and the 8200dx will be my office headphone amp.


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## SuperDuke

ForSure said:


> However, with the vkmusic upgrade part, this will be a overkill as a dedicated headphone amp.



In what way would you say it is overkill?  Too powerful for sensitive headphones?  thanks for the feedback


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## ForSure

First, the 8600 (with Lundahl upgrade) is a great sounding amp, which my wife approved the sound.  So happy using it as a home stereo amp.  The 8200DX is good enough for my HD6XX and AKG K702 headphone and the Audeze isine 10 IEM.  Personally, I will not spend $2K for a dedicated headphone amp,  that's why the 8600 is a overkill.  The opinion may change if I tried other headphone in the future.  I will spend the extra money for tube rolling, does this make sense?  On the other hand, I am so happy to get the 8600 with Lundahl, what an amp!  Purchase it if you are on the fence.  The 8600 is a limited run product and the VKmusic only have a couple Lundahl left, which make this a rare combo.  The Lundahl transformers are the special ingredient that make the 8600 amazing.


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## SuperDuke

Good clarification.  I'll check in after building mine. My intention was to use this amp for difficult to drive HPs.   the cost w/ upgrades does somewhat defeat the purpose of DIY however as 300B kits go it seems to be on par except for the transcendent sound kit mentioned earlier in this thread.


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## ForSure

Oh if you are going with the 8600, just go for the EVO Cap for now.  The Caps are easy to replace.  First settle on tubes, then consider a capacitor upgrade as a way of fine tuning the sound that last little bit.  Mudurf Cap need at least 60 hours to burn in before the high treble settle back down.  Great for Adele, ok for cellos.  Consider reading the final thoughts for the 8340 review before picking the a Cap. http://wallofsound.ca/audioreviews/...h-lundahl-transformers-and-triangle-speakers/


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## ForSure

Mine 8600 are purchased from VKmusic using the following for now
Mundorf Supreme EVO Silver Gold oil
Gold Lion Gold (B749 X 2 + B759 X 1) + Gold PX300B  X 2
Lundahl Transformer 
Takman Carbon Resistor

I purchased the 8200DX from VKmusic 4 years ago using the following for now
Mundorf EVO
Gold Lion B749 X 2
electro harmonix KT88 X2

Hopefully this help.


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## HiGHFLYiN9

ForSure said:


> Oh if you are going with the 8600, just go for the EVO Cap for now.  The Caps are easy to replace.


Exactly right... and you might want to use something other than Mundorf. The carbon film resistors make a very minor difference, but they are something you'd want to do up-front as replacing a bunch of resistors isn't too much fun and can damage the board if you're not careful. I personally wouldn't bother unless you also plan to replace the Alps Blue with something nicer like an Audionote, TKD or stepped attenuator. 

ForSure have you noticed any microphonics with the 300B? I know the Bottlehead BeePre can benefit from some weighting/damping of the 300B tubes as they can be a little on the sensitive side. Also, curious if you have heard any other tube amps you could compare to. Thanks


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## SuperDuke

Victor was nice enough to include the Takman resistors in my kit.  Glad I got the lundahls while they are still available.  I'll be able to compare to the Bottlehead Kaiju.  To me the Kaiju is quite a nice amp.  Somehow it's able to drive my 86db Monitors in a medium size space - not to earsplitting level but more than satisfying for Jazz


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## ForSure (Jan 24, 2018)

Comparing the different carbon film resistors made is like comparing sound quality between mid quality MP3 and FLAC.  While the Cap and tube change the signature of the sound.
When using the gold lion 300B, there isn't any microphonic.
Don't have any experience on different kind of potentiometer.
I "heard" from a lot of different amp.  But the one I had "listen" to are Elekit 8200, 8600, grace design and O2+.
When using the Oppo 205 as source, the 8600 with my LS50 bookshelf (rated 85db) can be loud.  Not so much when hooking up the turntable.


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## ForSure

How's your kit building?  I am trying the Audeze LCD2-Classic with the 8600 right now.  Will let you know how I feel.


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## SuperDuke

Nice!

I have mine almost 100% working.  Victor is sending some standoffs for mounting the lundahls that were not included and I have something is not quite right w/ the volume pot - cutting in and out when I push on it.  I think the pins are not in full contact w/ the jumper that connects the Pot to the PCB.   otherwise when it's working it sounds really good- no problem driving Susvara or 86db monitors.


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## ForSure

The volume pot is a little bit tricky.  But once it up, this thing is gold.


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## SuperDuke

The 8600 is a fantastic amp!  Sounds excellent with the Susvara.  Incredibly dynamic, detailed with tons of air.


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## ForSure

That's good news.  The sound it generate is so sweet.  I think mine get in the zone after the 100 hours mark.


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## ForSure

BTW, I set the headphone output jumper to "3" for the LCD2C.  You may want to play around with that too.  It is easy to change, all I have to do is removed the front plate.
Susyara!?  How does it sounds?


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## SuperDuke

I am driving the Susvara from the speaker taps.  have not tried them from the jack yet.  It's the best they have sounded.  TOne is incredible, very dynamic, detail and excellent stage


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## HiGHFLYiN9

Has anyone compared to the Bottlehead Mainline? I'd be very interested to hear how the two match up (ultra-premium DIY headphone amps).


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## SuperDuke

I don't have the mainline but did build the Kaiju and I prefer the 8600 to the Kaiju


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## Allanmarcus (Mar 1, 2018)

HiGHFLYiN9 said:


> Has anyone compared to the Bottlehead Mainline? I'd be very interested to hear how the two match up (ultra-premium DIY headphone amps).


I have a mainline on order, but I'm not sure you can compare these two. I don't have an 8600, BTW. The 8600, with tubes. The EleKit 8600 pricing is:
$1395 for the kit + $300 to $1200 (or more) for tubes
The MainLine is $1200 with tubes.

Ok, at $1700 (The Tube Store) the 8600 isn't _that_ much more.

Looking at VkMusic for the base model and all the upgrades (no tubes), the total is $2765 (I assume CA$), or $2155US - more than double the Mainline, once you add tubes.

Now if you compare to an Eddie Current, Woo WA5, or the new Cayin HA-300, the price is competitive, but not spectacular.
ELEKit with all upgrades and good, tubes: $2467
Woo WA5-LE: $3699
Eddie Current Balancing Act: NA new, ~$3500 used
Cayin HA-300: $3,999 (I think)
GemTune GP-01: $859 - ChiFi crap, but has VU meters!
ModWrite HA-300: $8000

ok, after doing that research, the $2467 is actually a pretty darned good deal. Still, it should be in another league compared to the Mainline.


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## SuperDuke

I can post more after I fix my volume pot and use the 8600 for awhile (waiting on a new jumper socket and pin header).  For now I can say I've not heard another amp like it with the Susvara- crazy dynamic, big open sound stage - just a joy to listen to.   I've not used the headphone out - just the taps.  It also does not break a sweat driving 86db monitors to more than comfortable volumes.


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## HiGHFLYiN9 (Mar 1, 2018)

Eh... in my experience it's hard to judge based on pricing alone. You're dealing with different domestic markets, direct purchase vs distributor, shipping costs of transformers across seas, and different engineers creating the circuit. If you purchase the Elekit in Japan, it's 108,000 Yen which is $1,016 dollars at the moment.

Just a random example, but I built a $700 Chipamp and it promptly replaced my Manley Stingray, there was no comparison. Just boils down to circuit design and your preferences. I like my S.E.X. better than my Mainline with some headphones like the Elear.

It's not hard to get a Mainline above $2K if you replace the caps/resistors/wiring/connectors/etc. : https://bottlehead.com/smf/index.php?topic=7152.15 ... whether it's competitive is another matter. Given my preference of 300B tubes I wouldn't be surprised if I liked the Elekit better, but I don't like to assume


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## SuperDuke

"Design and preferences" absolutely -

it's taken me awhile to know what kind of sound I really like.  I think if I was starting over in headfi I would ask myself "what kind of sound do I like?"  rather than "what amp is best" or "is this amp better than that amp?"   If I had to do it all over I'd have gone to more meets earlier on and heard a greater variety of gear.

that said - I have had great joy building kit amps.  I lucked out w/ the 8600 b/c I had the joy of building and ended up w/ a sound I really like.   To me it's Clear while still Rich w/ tone, Open with a large stage, and dynamic - all those are at the top of my list and whups... I said I was not going to go into impressions this early


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## ForSure

I want to say the Lundahl Transformer are the magic ingredients which make this amp so special.  Victor from Vkmusic know his stuff.  And consider the cost of Lundahl and the time he spent on R&D, this is a bargain deal.


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## SuperDuke

Victor has been a big help and always responds to emails promptly.


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## HiGHFLYiN9

You guys really should ditch that Alps Blue Velvet. The Alps is a great choice for a $200 amp but it makes no sense to have it in a $2,000 one. You're kinda driving a Ferrari with Pep Boys tires  Check out the TKD or a stepper if it fits.


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## Allanmarcus

Anyone heard of this amp?

Transcendent Sound "The Masterpiece": $699 + tubes
Way cheaper, but probably not as good. Question is, how much.


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## SuperDuke

HiGHFLYiN9 said:


> You guys really should ditch that Alps Blue Velvet. The Alps is a great choice for a $200 amp but it makes no sense to have it in a $2,000 one. You're kinda driving a Ferrari with Pep Boys tires  Check out the TKD or a stepper if it fits.



thanks for the suggestion!



Allanmarcus said:


> Anyone heard of this amp?
> 
> Transcendent Sound "The Masterpiece": $699 + tubes
> Way cheaper, but probably not as good. Question is, how much.



My guess is it is a very nice amp (I built one of his amps in the past).  I don't think It's as versatile for hard to drive planars and I think that price is w/o tubes. 

Once I work all bugs out of mine I'll report back w/ impressions compared to other HPs and amps.


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## HiGHFLYiN9 (Mar 5, 2018)

I found on another thread the Masterpiece has a capacitor-based output (no output transformers) and puts out 360mW into 100Ω cans, which should be very adequate for most headphones (although now-a-days headphone wattage output has gotten a lot higher for PMs).

Based on what is inside, along with the xformers and chassis, you get a lot for your money. The added chokes in the PS and silver mica caps are nice additions at this price level too. Also plenty of room inside if you want to add a big film cap in the PS 

...not saying this is better than the Elekit, but looks like a good option at the price.


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## HOOKEDONTUBE

Hi! Folks! Did anybody tried upgrading Elekit 8600 or lower model’s stock pot to stepped attenuator? Does it change/improve sonics? Thanks!


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## HiGHFLYiN9

I doubt there is room for a stepper, but an Audio Note or TKD would likely fit.


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## yates7592

Seriously considering buying one of these! There are 4x2 options for headphone output impedance apparently - low/high and 4-6.3ohm/8-16 ohm. How,if at all, do these figures relate to headphone impedance, say 300ohm? What is the default value and what are any owners here using? I read on another place that as the output 'z' goes up, the sound gets more full bodied but planktons get muddled up. Bass quantity also seem to rise as output 'z' goes up. For clarity and plankton, this guy settled on lower 1 setting.


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## SuperDuke

One year later and still very happy w/ the Elekit.  Getting ready to upgrade the Drivers to Telefunken G73R (12AU7 variant).  Of all the 300B tubes I've tried (Elrog, Sophia Electric, Takasuki , Valve Art and EH- I prefer the EML.  They are the most dynamic.   Only down side is they are so tall the front cage cannot fit - though I don't want to cover those nice triodes anyway! Maybe I'm crazy to put such $$$$ tubes in a kit amp - it sounds so good it's just begging for fancy glass


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## vkung

a piece of good Telefunken ECC83 or ECC803S is more impact of sound


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## AzmiAN

Which speaker sound best with this amp?


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## vkung

GOOD full range speaker....


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## AzmiAN

vkung said:


> GOOD full range speaker....



Can you name a few.


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## catcherfly

AzmiAN said:


> Can you name a few.



Audio nirvana drivers are very good, especially with the alnico magnets.

Common sense audio makes them


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## vkung

I use AER Driver


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## itsikhefez

HiGHFLYiN9 said:


> Has anyone compared to the Bottlehead Mainline? I'd be very interested to hear how the two match up (ultra-premium DIY headphone amps).



The first tube amp I built was the BH Mainline. I built it stock except the Auricap XO output caps. It was also the only tube amp I have ever heard for an extensive period. While I enjoyed it and thought it was a good amp, I did not think it was a significant improvement over my DIY SS amp, the RJM Sapphire v4. A few months later, I purchased the TU-8600R-VK for use with speakers. As I don't have any speakers yet, I thought it would be interesting to hear it with the headphone amp.
My expectation was that if it would sound different, it would probably be subtle and not obvious. Damn I was wrong.... the Elekit was a HUGE improvement over the Mainline.
For the first time, I heard what "air" is. The main improvements for me are the overall tone, the bass (it slams really hard), and layering/3D sound stage.
No upgrades except the Lundahl OPT's and TKD 2CP-601S pot. I used the stock resistors and Nichicon QXP coupling caps which I may replace later on.
The tubes I am using are Gold Lion PX300B, Telefunken ECC83 and RCA Cleartop 12AU7.



yates7592 said:


> How,if at all, do these figures relate to headphone impedance, say 300ohm?


I only tried it on the 1 setting. I'm using it mainly with ZMF Aeolus (300ohm) and rarely with HD650. Works great for both



SuperDuke said:


> Of all the 300B tubes I've tried (Elrog, Sophia Electric, Takasuki , Valve Art and EH- I prefer the EML.


Are you using EML-300B or EML-300BXLS ?
I was not sure if the heater regulator would handle the extra 0.25A and there was not a clear answer from Elekit.



AzmiAN said:


> Can you name a few.


I am going to pair mine with a Frugel-Horn Mk3 with Fostex FE126En drivers


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## yates7592

Anyone using the 8600 with HD800? Impressions?


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## vkung

Yes.. Very good with LCD3, HIFIman 1000, HD650 and HD800


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## HiGHFLYiN9

itsikhefez said:


> The first tube amp I built was the BH Mainline. I built it stock except the Auricap XO output caps. It was also the only tube amp I have ever heard for an extensive period. While I enjoyed it and thought it was a good amp, I did not think it was a significant improvement over my DIY SS amp, the RJM Sapphire v4. A few months later, I purchased the TU-8600R-VK for use with speakers. As I don't have any speakers yet, I thought it would be interesting to hear it with the headphone amp.
> My expectation was that if it would sound different, it would probably be subtle and not obvious. Damn I was wrong.... the Elekit was a HUGE improvement over the Mainline.
> For the first time, I heard what "air" is. The main improvements for me are the overall tone, the bass (it slams really hard), and layering/3D sound stage.
> No upgrades except the Lundahl OPT's and TKD 2CP-601S pot. I used the stock resistors and Nichicon QXP coupling caps which I may replace later on.
> ...



Thanks for the update, much appreciated. I personally moved on from the Mainline to the Linear Tube Audio MZ3, much more air, quieter background, more natural sound and holographic imaging. I agree that the Mainline is a good amp for the price, but it's not an end-game amp (at least for me). I met the Elekit rep last year at CAF and listened to the unit on speakers, I might have to bring my headphones along if I go this year. The LTA MZ3 is shockingly good though, it'll put up a very tough fight. 

Did you finish your frugels yet? It's a fun speaker.


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## SuperDuke

I am using the EML 300BXLS w/o any problems.  

I do have some nice 12AX7s to try at some point.  I would not be surprised if that makes a big difference - maybe more so than the 300Bs.

Not to get too far off topic - I built the Pass Amp camp amp kit from DIYaudiostore and for $327 it's hands down the best headamp for the $ I've heard.  Extremely simple to build and fun too.  If I could not build the Elekit for some reason I'd be very happy w/ this one - though it does not quite have enough drive for the Susvara (mono blocked it would for sure)

https://diyaudiostore.com/products/amp-camp-amp-kit?variant=7072933085218


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## itsikhefez

HiGHFLYiN9 said:


> Thanks for the update, much appreciated. I personally moved on from the Mainline to the Linear Tube Audio MZ3, much more air, quieter background, more natural sound and holographic imaging. I agree that the Mainline is a good amp for the price, but it's not an end-game amp (at least for me). I met the Elekit rep last year at CAF and listened to the unit on speakers, I might have to bring my headphones along if I go this year. The LTA MZ3 is shockingly good though, it'll put up a very tough fight.
> 
> Did you finish your frugels yet? It's a fun speaker.



The MZ3 looks interesting.. I have not heard much about it.
You described exactly what I experience with the TU-8600, air, black background, and holographic imaging.
I have subsequently sold the Mainline as well, and since this amp will go to speaker use, I'm building another SET design for headphone use.
It is a Tubelab SE based on 45 tubes (but can be easily converted to 2A3 or 300B). I used quality components such as DACT stepped attenuator and ElectraPrint OPT's.
It's not done yet.. I'm really hoping it will meet or exceed the TU-8600 for headphones.

I just received the FH3 flat-pak and apparently it is the last one planet10 had. I'm hoping to build it soon.
BTW, the posts on your blog have inspired me in both accounts (the Mainline and FH3).. great work!



SuperDuke said:


> I am using the EML 300BXLS w/o any problems.



Oh, thats great to know! Can you share what improvements it has over the other 300B's? Have you tried the Gold Lion's?


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## HiGHFLYiN9

LTA uses David Berning's tech, there's nothing like it on the market... and when David stops developing it, sadly I don't think anyone will be following in his footsteps. Not because it's not novel, but I don't think anyone gets it like he does. Mark Schneider, who is producing the latest designs, is far more OCD than I. He obsesses over the smallest details and spares no expense if he experiences an improvement in sound. I honestly don't know how he is making any money. Ceramic PCBs, non-magnetic custom toroid covers, Mundorf caps, Arduino-processed volume control, and absolutely no caps with steel leads. If you want a great sounding amp, make sure to run a magnet over those leads. Even the pricey audiophile options sneak them in. That's a priceless nugget from David Berning.     

I know you're a DIYer like myself, tube and solid state (and perhaps hybrid). If you look at the inside of LTA's amps, they follow an unusual topology. The schematics and tech write-ups are pretty foreign. It reminds me a little bit of Chord and their proprietary technology, something that no one else is currently offering. Granted, being in this hobby for as long as I have, I've become extremely averse to marketing hokum... but given how many amps I've put together and I just can't understand Berning's approach makes it pretty interesting in my book. As I get older, and more bored, the things that confuse me intrigue me the most, and I find they are worth obsessing over. Between astrophysics and Berning's tech, I could likely spend many lifetimes trying to wrap my head around each  

Very cool you're working on a Tubelab SE. I actually have all the pieces to build one, but I put it on hold. You chose the right tubes, although expensive the 45s sound like nothing else. I'm pretty sure George put at least one together for someone who wished to use it only for headphones, and I believe the result was quite satisfactory, but I'm going off of memory from many years ago. Between the Elekit and the SE, it will likely come down to the transformers. The ones I'm sitting on are Electraprint, which I'm not sure how they compare to the Lundahl. I know the Lundahl are more pricey.   

What's keeping me from building the SE? I'm currently I'm obsessing over 30-40 year old video game consoles which generally need some work to get up and running again... the mosfets and electrolytics are in bad shape, and there's some interesting ways to incorporate new tech to improve things a bit. The following over these things is similar to the DIY audio crowd. In due time I'll lose interest and go back to audio  

So glad you found my blog to be helpful. If you'd like to write a guest post on the Elekit, please feel free to reach out. I have another gent working on a steampunk Crack writeup that will be posted soon. 

My apologies for being semi-OT. Back to the Elekit!


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## baseonmars

Here’s a few build pictures - I put the TU-8600 VKR together about 3 weeks ago.

https://imgur.com/gallery/gAGInDY

I’ve just put some Telefunken input/driver tubes along with Erlog 300B in and couldn’t be happier. I thought I had heard some the best in amplification with the solid state BHA-1 but this is a whole new level of musical involvement.







Not sure I have too much more to add verbally, other than to say I have the tube bug real bad.


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## itsikhefez

Congrats! The TU-8600 is a sublime amp.... I ran mine with Gold Lion PX300B.
Wish I had the chance to hear them with Elrog as well.

Did you make any other upgrades?
Which headphones "transformed" the most on the TU-8600 vs the BHA-1?


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## baseonmars

itsikhefez said:


> Congrats! The TU-8600 is a sublime amp.... I ran mine with Gold Lion PX300B.
> Wish I had the chance to hear them with Elrog as well.
> 
> Did you make any other upgrades?
> Which headphones "transformed" the most on the TU-8600 vs the BHA-1?



I ran mine with Golden Lions for the first couple of weeks and enjoyed the sound immensely.

I went all in, Lundahl transformers, TAKMAN 2% resistors, Mundorf caps and TDK pot. I’ve build a few kit amps and while I’m confident at desoldering parts I find the results can be pretty messy. This ones for listening, not experimenting 

I must admit I’ve mostly been listening with speaker - the same pair I’ve had for 15 years have gained a whole new life.

I lost an entire evening listening with LCD-3s and results with HD800S have also been nothing short of stunning, guitars and other stringed instruments just “hung in the air“.

I have a feeling it’ll be moving out of the living room and into my headphone rig fairly soon.


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## Allanmarcus

Ummm, new amp from elekit. TU8800 set amp
https://www.diyaudio.com/forums/elekit/342879-elekit-tu-8800-set-amp.html

Not a 300b, but interesting. $1185 for base model, then $600 for Lundhal.
Tube for the 8800 should be cheaper than the 8600, since they re not 300b.

I recommend someone here get the itch real bad to build an 8800, then sell me their old 8600 at an awesome price


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## Allanmarcus

Anyone know what the difference is between the TU-8600R and the TU-8600S?


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## Jon L (May 12, 2020)

Allanmarcus said:


> I recommend someone here get the itch real bad to build an 8800, then sell me their old 8600 at an awesome price



Nah.. KT88 is simply not 300B SET  

Looks like TU8800 shares similar structure and layout as TU8600, which is not good news since it is PITA to change/service once it's built.
Just to change out coupling caps, I had to dissemble essentially the entire amp including the transformer mounts and whole circuit board since most parts (including coupling caps) are mounted on bottom of the board with no bottom panel on amp to access them.
In addition, if the amp develops problems, it is very difficult to troubleshoot since the transformers sit on top of board and get in the way of board access if one needs the amp to be turned on to troubleshoot 

I was hoping Elekit would rectify these issues but guess not...


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## baseonmars

Allanmarcus said:


> Anyone know what the difference is between the TU-8600R and the TU-8600S?



There's been no mention of internal changes, but the R is discontinued and the S is the new limited run. The big news is the newly designed Lundahl transformers which are available as an upgrade, and I would suggest they are all but mandatory.


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## Henrim

Has anyone tried the 8600 with Utopia? And has anyone compared it to the Feliks Euforia?


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## vkung

The S version Stereophile review will be available in May Edition.  Within 24 months, there are two Stereophile reviews for TU-8600 ( R and S)


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## smodtactical

Jon L said:


> Nah.. KT88 is simply not 300B SET
> 
> Looks like TU8800 shares similar structure and layout as TU8600, which is not good news since it is PITA to change/service once it's built.
> Just to change out coupling caps, I had to dissemble essentially the entire amp including the transformer mounts and whole circuit board since most parts (including coupling caps) are mounted on bottom of the board with no bottom panel on amp to access them.
> ...



Really unfortunate. I am considering this amp but dunno. This doesn't seem like good design?


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## smodtactical

HiGHFLYiN9 said:


> You guys really should ditch that Alps Blue Velvet. The Alps is a great choice for a $200 amp but it makes no sense to have it in a $2,000 one. You're kinda driving a Ferrari with Pep Boys tires  Check out the TKD or a stepper if it fits.



Whats funny is some very expensive preamps use RK27 alps pot like the VAC Renaissance V. MSRP is $13-14k . Jesus.


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## HiGHFLYiN9 (Aug 13, 2021)

What's even more ridiculous is all the overpriced speakers using low cost air motion tweeters. If you look at the below image these are ubiquitously present from $2,500 bookshelves to a $69,999 speaker that was just on the front of Stereophile.




They cost $40 a pair on aliexpress.


...it looks like the latest VACs are using ALPS most expensive RK series. They're like $700-800 last I checked. Glad they stepped it up


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## smodtactical

HiGHFLYiN9 said:


> What's even more ridiculous is all the overpriced speakers using low cost air motion tweeters. If you look at the below image these are ubiquitously present from $2,500 bookshelves to a $69,999 speaker that was just on the front of Stereophile.
> 
> 
> They cost $40 a pair on aliexpress.
> ...



Correct me if im wrong but I think the VAC Master has that pot too. And maybe even sig mk2a SE.


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## JamieMcC

Hi all great to see some familiar names here also. I found the thread after looking for info on the Elekit TU-8600SVK with the Llundahl LL2785B C-core output transformers.

Main use would be as a speaker amp so it's a bit of a bonus that its good performer with headphones as well. 

The Bottlehead Kaiju is also a consideration however the Elekit seems more widely reviewed.

Ps I'm also a Mainline owner and listening to the Bottlehead Sex amp via speakers at the moment also 😁

Cheers Jamie


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## itsikhefez

Hi Jamie... after building both the Mainline and the TU-8600 (I don't own either anymore though), I would recommend the Elekit.
I think at their prices it is a much better value. The Kaiju has what seem like rather small EI transformers, which the Lundahl are likely of much higher quality.
You do get the HP output which is nice, and the input tubes are more standard (12AU7/12AX7), although some people dislike those.
Also, building on the PCB is faster compared to P2P (cutting the wires to length on the Mainline was a real pain for me).


----------



## HiGHFLYiN9

Some of the old diy dudes are here  I owned the Mainline for a while and listened to the Elekit with the Lundahls at Capital Audio Fest. The Mainline has very close to a solid state sound, whereas the TU-8600 sounds like a well-made traditional 300B SET, warm yet detailed. I'd personally take the Elekit any day of the week, but it is a more expensive amp. I did have enough fancy parts in the Mainline to be the same price, so whether that is apples to apples I leave that to your judgement. I prefer the 6SN7, 12SL7, etc. driver tubes over the 12AU7 X 2 + 12AX7 in the Elekit, but we can't have it all, can we?  ...well, unless you want to pony up for the Cayin HA-300.

Jamie I know a fellow with a PCB you might be interested in. Sending PM.


----------



## smodtactical

HiGHFLYiN9 said:


> Some of the old diy dudes are here  I owned the Mainline for a while and listened to the Elekit with the Lundahls at Capital Audio Fest. The Mainline has very close to a solid state sound, whereas the TU-8600 sounds like a well-made traditional 300B SET, warm yet detailed. I'd personally take the Elekit any day of the week, but it is a more expensive amp. I did have enough fancy parts in the Mainline to be the same price, so whether that is apples to apples I leave that to your judgement. I prefer the 6SN7, 12SL7, etc. driver tubes over the 12AU7 X 2 + 12AX7 in the Elekit, but we can't have it all, can we?  ...well, unless you want to pony up for the Cayin HA-300.
> 
> Jamie I know a fellow with a PCB you might be interested in. Sending PM.


You think the ha300 is better than the elekit?


----------



## HiGHFLYiN9

They're similar in performance, I'd have to have them side by side to make that call. Given my attenuation, rectification and driver tube preferences I'd probably prefer the HA-300, but maybe there's some unknown secret sauce in the Elekit that would change my mind. Do note these are preferences versus better/worse, but the 300B is already a polarizing tube so you probably knew that already... some people would say 2A3s are better, some 45s, it's all in the ear of the beholder


----------



## JamieMcC

I noticed on the Elekit website they have a new amp due to be released this month that you can swap between 300b and 2a3 reads like it's just plug and play. Didn't see any pricing.


300B/2A3 SE POWER AMP KIT [ TU-8900E ]


----------



## HiGHFLYiN9

Nice! Here's a link for anyone interested: https://www.elekit.co.jp/en/product/TU-8900E


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## JamieMcC (Aug 17, 2021)

Posted today includes comparison to the Mainline


----------



## smodtactical

HiGHFLYiN9 said:


> They're similar in performance, I'd have to have them side by side to make that call. Given my attenuation, rectification and driver tube preferences I'd probably prefer the HA-300, but maybe there's some unknown secret sauce in the Elekit that would change my mind. Do note these are preferences versus better/worse, but the 300B is already a polarizing tube so you probably knew that already... some people would say 2A3s are better, some 45s, it's all in the ear of the beholder



How would ha300 or tu8600  compare to stellaris or ec studio or other totl amps?


----------



## HiGHFLYiN9

I personally haven't heard either. I prefer the Linear Tube Audio MZ3 over the HA300 with most headphones. It's very neutral and non fatiguing. The HA300 leans warmer and less resolving on the top end, but sometimes that can be nice. I think I have a still-active discount code for LTA if you decide you want to go that route.


----------



## smodtactical

HiGHFLYiN9 said:


> I personally haven't heard either. I prefer the Linear Tube Audio MZ3 over the HA300 with most headphones. It's very neutral and non fatiguing. The HA300 leans warmer and less resolving on the top end, but sometimes that can be nice. I think I have a still-active discount code for LTA if you decide you want to go that route.


Thank you! PMd


----------



## JamieMcC

https://www.diyaudio.com/forums/elekit/374425-elekit-tu-8900-2a3-300b.html


----------



## itsikhefez

I'm definitely not an expert but does a 12AU7 have enough drive capability for a 300B? I know atleast with the TU-8600S that it had 2 stages of gain. That said, it was also possible to use the 12BH7A with the Neurochrome DG300B so perhaps its fine.


----------



## HiGHFLYiN9

itsikhefez said:


> I'm definitely not an expert but does a 12AU7 have enough drive capability for a 300B? I know atleast with the TU-8600S that it had 2 stages of gain. That said, it was also possible to use the 12BH7A with the Neurochrome DG300B so perhaps its fine.


I think it might have to be wired in parallel based on this post: https://www.diyaudio.com/forums/tub...ted-amp-help-choose-circuit-design-print.html

...interesting that the tube cage is polycarbonate for IEC compliance.


----------



## JamieMcC

itsikhefez said:


> I'm definitely not an expert but does a 12AU7 have enough drive capability for a 300B? I know atleast with the TU-8600S that it had 2 stages of gain. That said, it was also possible to use the 12BH7A with the Neurochrome DG300B so perhaps its fine.



I know 12BH7A can also be used in the new TU 8900 in place of 12au7

From the designer on the diyaudio site 

*12BH7A instead of 12AU7*
TU-8900 is designed to use 12AU7 as voltage amplifying tubes. However, 12BH7A, with high driving ability, can also be used instead of 12AU7.


----------



## JamieMcC

I wondered if anyone here tried pairing the Hifi man HE6 with the tu-8600 300b amp?


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## JamieMcC (Aug 21, 2021)

Would someone be so kind as to let me know the uf value and voltage rating of the 6800 output capacitors.

TIA

Found answer don't worry


----------



## smodtactical

HiGHFLYiN9 said:


> I personally haven't heard either. I prefer the Linear Tube Audio MZ3 over the HA300 with most headphones. It's very neutral and non fatiguing. The HA300 leans warmer and less resolving on the top end, but sometimes that can be nice. I think I have a still-active discount code for LTA if you decide you want to go that route.


do you like the mz3 over the tu8600 ?


----------



## HiGHFLYiN9

I don't own the TU-8600. When it was at CAF the 8600 was playing on speakers and the MZ3 was playing on headphones, so it's hard for an apples to apples comparison. The MZ3 was the unit I eventually purchased, but that was primarily for headphone usage. The MZ3 speaker output is about 1 watt IIRC, whereas the 8600 is 8 watt, so if you are using speakers as well, they'd need to be quite sensitive for the MZ3. Currently with the speakers I use wouldn't get enough power out of either to be a proper mating, thus the speaker output wasn't a purchase consideration. 

The MZ3 does include a remote, warm-up output delay period, and a sophisticated volume control system, if those are nice-to-haves for you. I don't bother to use the remote but the other two are nice. I think they have a 14 day trial period if you're really on the fence...


----------



## smodtactical

I just bought tu8600 with all upgrade off USAM. Hopefully works on, will pair with ZMF atticus and hd800S.


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## smodtactical (Aug 29, 2021)

http://sonicvisions.org/forum/index.php?threads/elekit-tu8600s-impressions.118/

I got the elekit TU8600S in with most all upgrades in (only thing missing is VCAP CUTF, has odam instead). Tubes are: COSSOR Black Plate 300B, Western Electric  ECC83/B759, RCA 12AU7 X 2 (clear Top).

*Intro*
If I have to summarize the amp's sound with 1 word it would be captivating. I wanted to warm up HD800S and inject some musicality into it... the Elekit... well lets just say im lifting my jaw off the floor after hearing it.

*Setup*
I had some issues initially with a bit of noise and static. I fixed this by doing 2 things. First I took the XLRs out of my denafrips terminator that were connected to my he9, second I added to the tube cage. After doing this the elekit is insanely quiet with an abyss like blackground. I honestly think it sounds as quiet as the he9 and possibly even quieter than my pass amp.

*Tone*
The first thing that hits you is this supremely musical tonality throughout the frequency band. Now I know what the word 'effortless' means. Everything flows in such an utterly liquid way its truly amazing. Especially on hd800S at times it can just have too much bite or glare with certain music and now it sounds like its utterly relaxed and music just flows... but... it is somehow more detailed than my he9 ?!

*Detail*
Thats the next shocking thing is the detail. I am getting low level microdetail I never even heard in tracks. Trailing edges you never heard before seem to go on so long and perfectly disappear into the blackground. Female vocals sound utterly natural, real and I feel transported to the venue with the singer performing for me.

*Soundstage*
What also is amazing is the spatial + layering capability of elekit. The soundstage sounds bigger in all dimensions but there is real separation and layers to the music.. air around instruments... and imaging definition that I simply have not heard before in my headphones. Instruments and voices are clearly delineated that makes things very defined and placed yet it again is supremely musically cohesive. This adds to the sense of being truly immersed in the music which to me is my #1 quality that I look for in gear.

*Dynamics*
This thing slams like a truck! EDM sounds fast, detail and incredible punchy and impactful. The first time I put on Harvey McKay - Hard to See (Original Mix) I wanted to immediately get up and start dancing (but i controlled myself since I didn't want to embarrass myself in front of my wife lol). Elekit sounds just as powerful and brings the bass like he9 does but i think with more bass detail, texture and spaciousness... its simply less compressed sounding. Its more open, reverb is better appreciated as is the entire room of the recording.

*Comparisons*
I think the audio gd he9 is a great headphone amp. Its detailed, fast, big sounding but there is no comparison to elekit. Elekit is several tiers above. It does everything better. Detail, precision, 3d spaciousness while bringing a harmonic richness and flowing timbre that he9 just cannot even come close to. The sense of resolution married to a natural emotional sound has left me for the first time brought to tears. The only time this has ever happened to me before was listening to great speakers (including when i paired NS5000 with my pass labs amp). It has never previously happened with any headphones including (Susvara, TC, SR1a and all the head phones). This is a new stratosphere of performance that I've never even dreamed of.

*Pairings*
Everything I have sounds amazing on elekit. My favorite pairing so far is probably the hd800S... it just seems to love the tonal richness elekit adds. You get immense detail, speed, dynamic impact with a beautiful warmth that makes it SO EASY to listen to music... but you miss nothing compared to the HE9 and in fact there is more detail. The legendary soundstage of the 800S is enhanced further.

HD650 has always been a headphone that I considered a more 'whatever youtube/gaming' headphone. It sounded fine with music but I didn't take it seriously. That changed with elekit. Detail is taken up 2 notches, again more of a big 3d sounds tage... but with this combination you are utterly bathing in beautiful rich tonality... it sounds so natural and beautiful and once I put the headphone on my head... and listened for some period of time.. I said ok now its time to switch to HD800S or Atticus... but.. my hands would simply not move to the headphones to take them off my head. In fact they are still on my head as type this LOL.

ZMF Atticus is the supreme king of darkness. I love that headphone. When I directly compared it to abyss TC on my pass labs speaker amp I found it had more overall bass quantity, impact and slam to the point that abyss tc sounded bass light (and yes I had TC fit right.. and TC bass is still awesome for sure). Pairing with the elekit is fantastic. Again there is more detail, more space and even warmer tonality. Now here i think its possible the pass amp may be a bit better of pairing because i think its a brighter sound that balances the darkness of atticus better... but honestly.. its like drowning in dark chocolate and you just have a big dumb goofy smile on your face when you listen to it. The atticus is the most fun headphone I have ever heard in my life period and sounds just fantastic on the elekit. The thunderous bass is maintained... there is added detail, 3d space, richness in spades... again possibly a bit TOO dark but I honestly still love the pairing.

*Summary*
Wow. My first introduction to tubes. I was previously obssessed with SS and wanted to get TOTL planars. I have lost all interest in that right now. I just want to close my eyes and bathe in the beautiful harmonies that emanate from this incredible amp with my relvatively humble dynamic headphones. I still cannot comprehend how an amp can sound this musical, rich but also incredibly detailed, fast with this much dynamic impact. I cannot recommend Elekit tu8600S more highly. A huge thanks to my bros in the SV discord for #1 getting me into tube world and to the elekit and helping me trouble shoot espescially the genius Baseonmars and also Famish, Sina, driftingbunnies, Jsim, Lana, MShenay, Parker, Eaglewings, Audio noodle, dnceclectic, Xecuter, Tron, Fishcommander, voxkey, Aman, ho lee ***, Jonah, Vanilla hoon (if I missed someone so sorry thank you too).


----------



## JamieMcC

Arrived today TU-8900 with 300B and 2A3 tubes to try out, I hope to get it up and running next week.


----------



## HiGHFLYiN9

Great news!


----------



## ForSure

JamieMcC said:


> Arrived today TU-8900 with 300B and 2A3 tubes to try out, I hope to get it up and running next week.


Dude, Lundahl is the bomb!!  I know you will love it.  Please keep us update.  I want to know what you think about the headphone out on this thing.  My 8200DX is too powerful for most of the headphone and I don't have time to mod it.


----------



## ForSure

smodtactical said:


> http://sonicvisions.org/forum/index.php?threads/elekit-tu8600s-impressions.118/
> 
> I got the elekit TU8600S in with most all upgrades in (only thing missing is VCAP CUTF, has odam instead). Tubes are: COSSOR Black Plate 300B, Western Electric  ECC83/B759, RCA 12AU7 X 2 (clear Top).
> 
> ...


Great review.

I have the original 8600 with Lundahl and Mundorf.  I found it sound best with planar headphone.  I do want to change the cap to Vcap because I believe the Mundorf push the treble too much.


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## Whitigir (Sep 26, 2021)

So in order to get this amp to run Balanced in and Balanced out.  Do you think transformers will do the job ? Or will it effect sound too much


----------



## ForSure

Whitigir said:


> So in order to get this amp to run Balanced in and Balanced out.  Do you think transformers will do the job ? Or will it effect sound too much


I don't know much about balanced thing.

In elekit, the left and right signal are separated from the start and there is no cross interfere within unlike some single tube design.  

The Lundahl bring the clarity to another level.


----------



## Whitigir

ForSure said:


> I don't know much about balanced thing.
> 
> In elekit, the left and right signal are separated from the start and there is no cross interfere within unlike some single tube design.
> 
> The Lundahl bring the clarity to another level.


Do you know where I can download the schematic ? This look like candy to me lol


----------



## ForSure

that's something elekit won't release until you purchased the kit (which they included in the kit).

I remember when I was a kid, they have magazines that publish schematic and you can just build accordingly.


----------



## Whitigir

ForSure said:


> that's something elekit won't release until you purchased the kit (which they included in the kit).
> 
> I remember when I was a kid, they have magazines that publish schematic and you can just build accordingly.


What in the heck ? LOL? Then how would I know what I need to do to get balanced in and out with this kit 😂.  Thanks for the confirmations


----------



## ForSure (Sep 26, 2021)

Whitigir said:


> What in the heck ? LOL? Then how would I know what I need to do to get balanced in and out with this kit 😂.  Thanks for the confirmations


Every company has their "policy".

I understand how you feel.

Maybe you should go to DIYAUDIO https://www.diyaudio.com/forums/elekit/ and talk to Victor.  He is the North America dealer for Elekit.


----------



## JamieMcC (Sep 29, 2021)

I've made a start assembling my Elekit  TU-8900 yesterday. Thought I would post a few pics of how well the kit was packed and where I'm up to with the build after two days.

 I've been talking it slow and steady probably around 8hrs in all so far 5hrs yesterday and about 3hrs today. Probably two or three more hours to go tomorrow hopefully and I will be up and running unless there is a bit if trouble shooting required, fingers crossed.

So far it's been very enjoyable the quality of Elekits PCB layout and clear and easy to follow instruction manuals has impressed. It was a bit of a surprise on unpacking  to find the metal chassis came partly assembled as well which was neat and makes assembly just that little bit easier than the normal stack of flat metal plates.


----------



## Whitigir

Nice going, I heard there is a long wait for the kit ATM.  Anyone has a kit that they are not building and want to pass on ?


----------



## ForSure

Whitigir said:


> Nice going, I heard there is a long wait for the kit ATM.  Anyone has a kit that they are not building and want to pass on ?


Have you contact Victor?


----------



## Whitigir

ForSure said:


> Have you contact Victor?


Yes and that was what he mentioned, a long list of waiting


----------



## HiGHFLYiN9

Whitigir said:


> Yes and that was what he mentioned, a long list of waiting


He said the same to me and that was a month ago. Supply chain issues I'm sure....


----------



## ForSure (Sep 29, 2021)

HiGHFLYiN9 said:


> He said the same to me and that was a month ago. Supply chain issues I'm sure....


Just chatted with Victor, he has couples 8900 just not the Lundahl opt.  It is cheaper to ship the 8900 with the Lundahl opt together, that's all.

For my experience, Lundahl is a must have.


----------



## ForSure




----------



## HiGHFLYiN9

How do you like the Sunvalley phono-pre?


----------



## ForSure

HiGHFLYiN9 said:


> How do you like the Sunvalley phono-pre?


Make me wonder why I spent so much money on other phono amp.

My search for phono stop here (for now, lol)


----------



## Whitigir (Sep 29, 2021)

ForSure said:


> Just chatted with Victor, he has couples 8900 just not the Lundahl opt.  It is cheaper to ship the 8900 with the Lundahl opt together, that's all.
> 
> For my experience, Lundahl is a must have.


I found tubedepot to have the $1495 kit but has no tubes ?

I will be joining in the fun.  Victor mentioned that I can use balanced source with the Amp.  So I think I am safe.


----------



## ForSure (Sep 29, 2021)

Whitigir said:


> I found tubedepot to have the $1495 kit but has no tubes ?
> 
> I will be joining in the fun.  Victor mentioned that I can use balanced source with the Amp.  So I think I am safe.


Tube and upgrade parts always sold separately. 

Victor has 8900 with the stock opt in hand and ready to ship.

His diyaudio user name is Vkung


----------



## Whitigir (Sep 30, 2021)

Ok, so it look to me that the input stage is actually SingleEnded.  While using Balanced source such as DAC with XLR out can be used with cables that does XLR to RCA is possible, it should only be possible with the DAC that has differential stages within itself.  That means despite the fact that it is using XLR out, the signals really is just being sent as SingleEnded.

Then, in order to really utilize the Balanced output of any DAC and Source  while preserving the integrity.  There needs to be a Balanced input stage, possibly dual input transformers and wire directly into the PCB

Now, output stage look to be Single Ended and volume control is Dual Gang.  So the amp is single ended architecture but with transformers output! Look good to me!!  Just need balanced input with transformers to take advantage of balanced out sources 

please correct me if I am wrong


----------



## HiGHFLYiN9

If you want to have balanced input you'd need a pair of small transformers. Cinemag and Jensen both make them. I believe you also need to integrate a pair of resistors; you can check with them about the value.


----------



## JamieMcC

Operation checks and voltage check point readings passed.

No troubleshooting required.

It's alive....


----------



## Whitigir (Sep 30, 2021)

HiGHFLYiN9 said:


> If you want to have balanced input you'd need a pair of small transformers. Cinemag and Jensen both make them. I believe you also need to integrate a pair of resistors; you can check with them about the value.


I am planning with Lundahl dual transformers now LL1690.  It doesn’t seem that it needs any resistors.  The line in should be already with some kind of gains as the 8900 has the preamp tubes.  So the transformers go right up to the input stages of RCA is alright.  It is better than just going straight Balanced to SE

However, I need to see the schematic to judge further.  Jensen recommend 2.4K resistors for between the output of RCA.  Lundahl recommend a couple resistors and a cap


----------



## Whitigir

JamieMcC said:


> Operation checks and voltage check point readings passed.
> 
> No troubleshooting required.
> 
> It's alive....


Are you using the C cores ? Or the AM cores ?


----------



## JamieMcC

I went for the Lundahl amorphous core version with V-Cap CuTF capacitors and TDK indented pot options.


----------



## Whitigir

JamieMcC said:


> I went for the Lundahl amorphous core version with V-Cap CuTF capacitors and TDK indented pot options.


Very nice build!! And expensive too !!! Lol ? Any chance to try EAT 300B tubes ?


----------



## JamieMcC (Sep 30, 2021)

Thanks I'm very pleased with the results and it's  early days so far.  Currently running the COSSOR/Linlai WE300B. I was originally going to go for the Cossor Black plates but was encouraged to go for the WE300B by an experienced 300B guy whom I've know for over ten years and who's advice I have high regard for.

Also purchased the COSSOR/LINLAI WE2A3 from Victor but have yet to try them.
No plans for trying other 300B's at the moment.


----------



## HiGHFLYiN9

Does the Linlai WE300B have any sort of guarantee? My brain has trouble wrapping around eight hundo for a pair of tubes


----------



## Whitigir

HiGHFLYiN9 said:


> Does the Linlai WE300B have any sort of guarantee? My brain has trouble wrapping around eight hundo for a pair of tubes


Check out that ETB 300B . It is about double that much lol!!

I don’t know about those tubes but I will build this for HD800S prioritized, so 2A3 seems to be a good option


----------



## JamieMcC

The Cossor WE300B were $535 a pair not inexpensive but still significantly less than the USA WE300B reissue. Both plate structures are said to be identical.

I think the warranty for the Cossor WE300B is for 90 days.


----------



## Whitigir

JamieMcC said:


> The Cossor WE300B were $535 a pair not inexpensive but still significantly less than the USA WE300B reissue. Both plate structures are said to be identical.
> 
> I think the warranty for the Cossor WE300B is for 90 days.


Have you tried to compare 300B / 2A3 yet ?


----------



## JamieMcC (Oct 3, 2021)

Whitigir said:


> Have you tried to compare 300B / 2A3 yet ?


To early yet to make comparison on fresh amps they really need a couple of hundred hours on both tube sets before making any meaningful comparisons. fwiw TU8900 with Cossor WE300B is opening up nicely currently at 50hrs, definitely preferable sonics (to me) compared to fresh 2A3.
However that observation may well be reversed when I have 50hrs on the 2A3 will have to wait to find out...

Worth repeating its way to early to draw any meaningful conclusions on sonics without at least 200hrs plus of run time on the amp and both tube sets, roll a few different input tubes, try different settings etc.

 But fwiw Im enjoying how it sounds.


----------



## Whitigir

I have tried different things on the kit.  I only successfully implemented balanced 4.4mm as it is the connector I use the most.  Could easily do XLR but not necessary.  I failed to implement transformers differentials from XLR sources into the single ended rca in the back though


----------



## Whitigir

The amp sound much better when warmed up after 30 minutes or so, the details and high extensions just come out much better.  I will upload a detailed build PDF later


----------



## normie610

Whitigir said:


> The amp sound much better when warmed up after 30 minutes or so, the details and high extensions just come out much better.  I will upload a detailed build PDF later


seems like you’re going back to desktop setup?


----------



## HiGHFLYiN9

Whitigir said:


> I have tried different things on the kit.  I only successfully implemented balanced 4.4mm as it is the connector I use the most.  Could easily do XLR but not necessary.  I failed to implement transformers differentials from XLR sources into the single ended rca in the back though


So you received the Elekit as well? You may want to post your quandary over at DIYAudio.com.


----------



## Whitigir

As promised, I have prepared al the documents for my build including “how to” modifications to run additional headphones or floating balanced and balanced transformers input.

you can download it here as a PDF .  It is 1Gb! Enjoy !!


----------



## JamieMcC (Oct 8, 2021)

Whitigir said:


> As promised, I have prepared al the documents for my build including “how to” modifications to run additional headphones or floating balanced and balanced transformers input.
> 
> you can download it here as a PDF .  It is 1Gb! Enjoy !!



I wanted to say that's a really impressive write up and commend you for your effort in providing the pdf of your build it will I am sure become a invaluable reference for anyone wishing to build the amp either stock or as balanced.


----------



## Whitigir

JamieMcC said:


> I wanted to say that's a really impressive write up and commend you for your effort in providing the pdf of your build it will I am sure become a invaluable reference for anyone wishing to build the amp either stock or as balanced.


Thank you much! This amp is amazing!!! I just love it


----------



## JamieMcC (Oct 8, 2021)

Whitigir said:


> Thank you much! This amp is amazing!!! I just love it



Your welcome.

I passed the 100hr mark yesterday on my amp with the Cossor WE300b and the sonics have noticeable improved over this time and I think will most likely continue to do so for a while yet.

From past experiences with Teflon capacitors I know the long burn in required is very real. 

I've started building the hours on my 
WE 2A3 tubes I had been conscious that my initial impressions of the amp running the 2A3 were not inline with others which is why  I've been a bit reluctant to comment when asked on different threads and BBs.

These initial impressions I think have been predominantly due to my 2A3 tubes being new combined with maybe a leaner presentation of my dac.

With roughly 15hrs on the 2A3 now sonics are I am pleased to say are very much improved and definitely more inline with feedback from others users here.

I'm thinking that the WE2A3 if they prove to be similar to the Cossor WE300B will require a good few hours before revealing their true virtues. With that in mind and how much the 2A3 have improved with just 15hrs and how good things sound at the moment if they continue to improve as the WE300b did the prospect of what's to come with100hrs + on them has me quiet excited.

Good things come to those who wait....


----------



## Whitigir

I was floored as soon as the amp turned on.  The depth of stage and the width is crazy.  I noticed that Bass and sub bass density wasn’t there as much as I wanted but the soundstage was amazing.  The details and sub bass density improves after 30 minutes, and I have been running it overnight.  I have had it now burned in for only 24 hours, but it is such an amazing amp for sure .  I may need to grab the WE300 or so when I can , and what is the best ECC82 ?


----------



## JamieMcC

Whitigir said:


> I was floored as soon as the amp turned on.  The depth of stage and the width is crazy.  I noticed that Bass and sub bass density wasn’t there as much as I wanted but the soundstage was amazing.  The details and sub bass density improves after 30 minutes, and I have been running it overnight.  I have had it now burned in for only 24 hours, but it is such an amazing amp for sure .  I may need to grab the WE300 or so when I can , and what is the best ECC82 ?


 
I've only tried three different input tubes so far mainly running the 12bh7 but also Mullard cv4003 box plates and Brimar 6067 T which is a substitute. I had these from a previous amp  all have sounded really very nice with subtle differences.

Some transplant surgery the donor my Bottlehead Mainline the bypass caps from its RTI 10uf teflon output caps. No room on top of the pcb but plenty underneath.


----------



## Whitigir

JamieMcC said:


> I've only tried three different input tubes so far mainly running the 12bh7 but also Mullard cv4003 box plates and Brimar 6067 T which is a substitute. I had these from a previous amp  all have sounded really very nice with subtle differences.
> 
> Some transplant surgery the donor my Bottlehead Mainline the bypass caps from its RTI 10uf teflon output caps. No room on top of the pcb but plenty underneath.


Nice!! It is the first time I see that one .  For the Silver foil, there are AudioNote .  I am not sure if it fit , but they are also expensive


----------



## JamieMcC

They are the Duelund JDM silver foil bypass capacitors.  Have had good results using them in other amplifiers I think they are a bit of steal for the performance they being to the table. As I already had them it would be rude not to give them a try.

https://www.partsconnexion.com/DUELUND-87178.html


----------



## Whitigir

I have it burned in about 35 hours now.  After 25 hours of burning in, trebles extensions and upper mids are harsh , with edginess and sibilant on cold start up, and after 2 hours or so, the sound becomes more mellow and delicate with great textures fidelity.

Also noticed that I burned in my Gold Lion 300B for about 10 hours, I also swapped it out a couple times during that 25 hours of the amp burning in and observed a much more severed effects of harshness and sibilants.  However, the depth of stage and width are much more than the WE2A3 from LinLai


----------



## Whitigir (Oct 12, 2021)

Burning in tubes amp does take forever lol.  However, At this moment, what I am hearing is that the 8900 is a total beast, Hi-Fi as audiophile as one can go.  The soundstage is “Vast”, and I literally meant that.  I used to have Stax 009 and T2 amp.  This amp is not lacking behind in driving my 800s at all.  This is only with Gold Lion 300B.  What will Western Electric 300B do ? One of the reason I jump into WE300B is the 5 years warranty.  Sounds can come later 😆

Not only that it sound amazing, but it is so much friendly to tubes and rolling tubes (yes, very much poison here)…I am waiting for more tubes to come and I already have spent a chunk !!

What is more comforting than an amplifier that can automatically detect tubes and auto adjusting it bias ?

Also, the point to point connections for this amp is very much possible.  I did that for 90% of the joins.  Even though my build is a build and modifications together for the endgame as a goal.  This amplifier in it foundations is totally “High-End and Hi-Fi” as much as one can go, no questions, no doubt, and I am running it constantly for Headphones with High impedance load.  Also running over nights every day without worrying

*Japan engineering, designs*!! This here is a money shot.


----------



## Whitigir

Also worth mentioning is that the ability to take in both 2A3 and 300B is with the newest kit 8900 and not the 8600 as in the pictures


----------



## EagleWings

@Whitigir , I saw your post about the noise on DIYA. But I thought I'll bring the discussion here, as I feel more at home, and the UI here is a little better. I am wondering if it is either ground noise or simply the high noise floor you are hearing out of the headphone, due to high gain of the amp. I see that you have made a dedicated pentaconn output. Are you connecting the pentaconn directly to the 16 Ohm secondary winding of the OPT and running it Single Ended? 

@JamieMcC , how is the amp responding to rolling the coupling caps? I skipped the V-Cap, which I hear can be quite revealing and have picked up Audyn's Copper Max. I am going to try a couple of tweaks to push the tone of the amp towards the organic side, without having to rely on very warm sounding tubes.


----------



## Whitigir

EagleWings said:


> @Whitigir , I saw your post about the noise on DIYA. But I thought I'll bring the discussion here, as I feel more at home, and the UI here is a little better. I am wondering if it is either ground noise or simply the high noise floor you are hearing out of the headphone, due to high gain of the amp. I see that you have made a dedicated pentaconn output. Are you connecting the pentaconn directly to the 16 Ohm secondary winding of the OPT and running it Single Ended?
> 
> @JamieMcC , how is the amp responding to rolling the coupling caps? I skipped the V-Cap, which I hear can be quite revealing and have picked up Audyn's Copper Max. I am going to try a couple of tweaks to push the tone of the amp towards the organic side, without having to rely on very warm sounding tubes.


Hello @EagleWings , the noises I observe is figured out to be the ground loop from the XLR I connected.  If without the XLR balanced, then it is super quiet.  So, I will have to figure out another way.  Right now I am running a straight box from balanced in to rca out, so I am still skipping a few solder joins.

The headphones is connected from the phones out.  Running single ended


----------



## EagleWings (Oct 12, 2021)

Are you using the Shanling M30 to feed the 8900? A desktop DAC that is properly grounded (which are 95% of the reputable desktop DACs) wouldn't give you that issue. I say that because when I used to run my Hugo2 and Cayin N8 as DACs into my desktop amp, I used to have ground noise in most power sockets. But I am sure there must be a solution to fix this in your case. After all, one of the purposes of XLR to RCA isolation transformers like the Jensen ISOMAX Pi2XR is to not let any ground noise pass through.


----------



## JamieMcC (Oct 12, 2021)

EagleWings said:


> @JamieMcC , how is the amp responding to rolling the coupling caps? I skipped the V-Cap, which I hear can be quite revealing and have picked up Audyn's Copper Max. I am going to try a couple of tweaks to push the tone of the amp towards the organic side, without having to rely on very warm sounding tubes.



Hi the truthful answer is I couldn't say one way or the other as yet with regards to cap rolling but I see no reason why it wouldn't.

Adding the Duelund silver bypasses did help but only in the context that they helped mask somewhat the unnatural harshness associated with the v+cap cutf prior to it smoothing out as they do once they have 300-400 hrs on them.

The Audyns are good caps I ran some non copper ones in another amp.

I've used Teflon capacitors in several other amplifier builds and have noticed similar sonic characteristics whilst settling in.

While the V-caps don't quite sound the bee's knees right now they are still pretty good am I'm reasonably confident that they will improve significantly with run time and the wait will be worth it.


----------



## Whitigir (Oct 12, 2021)

EagleWings said:


> Are you using the Shanling M30 to feed the 8900? A desktop DAC that is properly grounded (which are 95% of the reputable desktop DACs) wouldn't give you that issue. I say that because when I used to run my Hugo2 and Cayin N8 as DACs into my desktop amp, I used to have ground noise in most power sockets. But I am sure there must be a solution to fix this in your case. After all, one of the purposes of XLR to RCA isolation transformers like the Jensen ISOMAX Pi2XR is to not let any ground noise pass through.


That is very true that the M30 does not give the ground loop issues.  But if I was to use other sources as you mentioned, a DAP, then I am facing the issues.  
I agreed about galvanic isolations on the transformers, and as you mentioned, it should have isolated it.  I have tried many different ground paths to kill the ground loop but is not successful.  There is some funkiness going on.  I will have it figure out sooner or later


----------



## EagleWings (Oct 12, 2021)

JamieMcC said:


> Hi the truthful answer is I couldn't say one way or the other as yet with regards to cap rolling but I see no reason why it wouldn't.
> 
> Adding the Duelund silver bypasses did help but only in the context that they helped mask somewhat the unnatural harshness associated with the v+cap cutf prior to it smoothing out as they do once they have 300-400 hrs on them.
> 
> ...


That’s good to know. Because on some amps, swapping coupling caps hardly have any effect.



Whitigir said:


> That is very true that the M30 does not give the ground loop issues.  But if I was to use other sources as you mentioned, a DAP, then I am facing the issues.
> I agreed about galvanic isolations on the transformers, and as you mentioned, it should have isolated it.  I have tried many different ground paths to kill the ground loop but is not successful.  There is some funkiness going on.  I will have it figure out sooner or later


Great that there is no noise with the M30. Might be worth it to contact Jensen and see if they can help.


----------



## Whitigir (Oct 12, 2021)

EagleWings said:


> That’s good to know. Because on some amps, swapping coupling caps hardly have any effect.
> 
> 
> Great that there is no noise with the M30. Might be worth it to contact Jensen and see if they can help.


I don’t think it is on the Jensen side of things.  It is on the amp and the way I am trying to modify it.  I will have it figured out sooner or later

i have the Jensen working out nicely when I have it boxed up separately with RCA out.  So it is all working as intended.

The decoupling caps on the 8900 should be one of the main reason to color your sound.  It is intentionally designed to be able to accommodate larger caps for this very reason.  I like the V-Cap CUTF very much for the “wide bandwidth” as Viktor put it.  It has a very nice reach on both ends of the spectrums, though I have my amp burning in.  It is swinging back and forth on both ends…I am unable to pin point the components that does….but I believe the CUTF is one of those guys.  It is a worthy option to upgrades together with Lundahl output transformers.  The lead for the V-Cap is solid copper, and I love it so.  It can easily be direct wiring from legs to legs for point to point.

Another possible upgrade is Audio Note. 22x40mm which will fit nicely, and the lead is Litz Silver 
Audio Note Capacitor 0.1uF 600Vdc Silver Foil​


----------



## Whitigir

Finally!! I believe I solved the hums issues.  It was part of the ground loop for balanced input.


----------



## Whitigir

Gotta love all of these lights and Lamps !


----------



## JamieMcC

My Cossor WE300B do the same 

If you have a bit of a Google the glow looks like it is in the same position as it commonly appeared with the original Western Electric 300B which I guess you could say is testament to Cossor's attention to detail in recreating the original plate structures of the WE300B as closely as possible with their version.

Mind I have not tried any other 300b so they may all have the glow in the same position for all I know 😁


----------



## Maven86

Built this a couple weeks back.  Lundahl amorphous, and Duelund CAST silver for coupling caps.  Was curious what everyone elses preferences were between feedback and non-feedback mode?


----------



## HiGHFLYiN9

Magnific!


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## JamieMcC (Oct 22, 2021)

Maven86 said:


> Built this a couple weeks back.  Lundahl amorphous, and Duelund CAST silver for coupling caps.  Was curious what everyone elses preferences were between feedback and non-feedback mode?



Still experimenting myself most of my listening has been with feed back I did run with no negative feedback but only for an afternoon early on.  Got to give it try again as my tubes were still freshish at the time.  Both my Cossor WE300B and Cossor 3A3 tubes I feel have noticeable improved now with 100+ hours on them. 

Think I need to spend longer listening  with no negative feedback to get a better handle   on the differences. 

Were the Duelunds a relatively easy fit I haven't looked at their dimensions?


----------



## JamieMcC

@Maven86 I know a loaded question but how do you feel the TU-8900 compared to your Eddie Current Aficionado I noticed it was recently for sale/sold?


----------



## JamieMcC

Edit just noticed your write up SBAF are we allowed to link ok going to try see if it gets moderated or not.

https://www.superbestaudiofriends.o...ild-impressions-and-review.11541/#post-363207


----------



## HiGHFLYiN9

JamieMcC said:


> Edit just noticed your write up SBAF are we allowed to link ok going to try see if it gets moderated or not.


I'm really looking forward to the comparison to the DNA Stratus.


----------



## JamieMcC

HiGHFLYiN9 said:


> I'm really looking forward to the comparison to the DNA Stratus.



Yes me to I hadn't read the full thread on sbaf prior to posting.

It's eagerly anticipated I remember bigfatpaulie speaking very highly of his Stratus.


----------



## Whitigir

Maven86 said:


> Built this a couple weeks back.  Lundahl amorphous, and Duelund CAST silver for coupling caps.  Was curious what everyone elses preferences were between feedback and non-feedback mode?


Congratulations!! And Awesome looking! How does Duelund fit in there ?

In my opinion, NFB is excellent with 2A3, it gives the sound a little more liveliness and punchiness rather than being too mellow and too thick.  It certainly makes the 2A3 sounds a lot more enjoyable

However, with 300B, and especially Western Electric 300B, the Non Negative Feedbacks give it a more authentic tonality as in realism tonal body, everything feels more natural without the artificial speediness that Mimic Solid States, and also vocal sound more addictive.


----------



## Allanmarcus

Maven86 said:


> Was curious what everyone elses preferences were between feedback and non-feedback mode?


I find it odd about asking for feedback on non-feedback!


----------



## Maven86

Whitigir said:


> Congratulations!! And Awesome looking! How does Duelund fit in there ?
> 
> In my opinion, NFB is excellent with 2A3, it gives the sound a little more liveliness and punchiness rather than being too mellow and too thick.  It certainly makes the 2A3 sounds a lot more enjoyable
> 
> However, with 300B, and especially Western Electric 300B, the Non Negative Feedbacks give it a more authentic tonality as in realism tonal body, everything feels more natural without the artificial speediness that Mimic Solid States, and also vocal sound more addictive.


Thanks!  The Duelunds are actually too big for the capacitor spaces so I actually had to fasten them under the main board:




Your impressions on NFB seem to be pretty similar to mine.  Had a couple friends (non-audio guys) take a listen to both and they all preferred the NFB on.  I guess I'm the odd one out with liking it off, everything is cleaner and clearer with it on and the bass is tighter, but it sounds a little too 
"proper" for my tastes.  I'll probably have to give it more of a listen again to see if things will change over time.


----------



## Maven86

JamieMcC said:


> Still experimenting myself most of my listening has been with feed back I did run with no negative feedback but only for an afternoon early on.  Got to give it try again as my tubes were still freshish at the time.  Both my Cossor WE300B and Cossor 3A3 tubes I feel have noticeable improved now with 100+ hours on them.
> 
> Think I need to spend longer listening  with no negative feedback to get a better handle   on the differences.
> 
> Were the Duelunds a relatively easy fit I haven't looked at their dimensions?


Fair enough, things have definitely changed from day 1 for me as well.


----------



## Whitigir

AudioNote pure silver foil should be the direct drop in replacement for Vcap CUTF.  However, they are expensive and only special order then wait for a few months, which I won’t be


----------



## JamieMcC (Oct 24, 2021)

After the recent conversations here I decided to switched over to running without negative feed back for the last couple of days using the 300b tubes and I definitely have a preference for listening with my speakers when using negative feedback. I really like the extra sense of presence and increase in tone density without feedback but when running with feedback sonics feels faster and more dynamic bass is more defined and controlled and has more snap and punch which I miss when running without feedback.

However when listening with headphones Senn hd800 with sdr mod running without feedback is preferred as those differences seem much smaller and with the hd800 that little bit of extra presence and density of tone feels beneficial.

This has surprised me.

I can happily listen either way as both with or without feedback it's super enjoyable for slightly different reasons which is a really nice feature of the TU-8900.


----------



## Beefy

JamieMcC said:


> However when listening with headphones Senn hd800 with sdr mod running without feedback is preferred as those differences seem much smaller and with the hd800 that little bit of extra presence and density of tone feels beneficial.


Given the HD8xx series' reputation as being very detailed bordering on dry, I'm not surprised. The higher gain in non-NFB mode is probably no problem as well.

On that note..... I wonder if anyone in this thread is willing and able to take some gain measurements at different output impedance settings, with and without a headphone load connected? This would allow calculation of true output impedance and damping factor.

This is the sort of data that I am thinking of. But with the addition of measuring voltage at the attenuated side of the volume pot, in order to calculate apparent voltage gain.


----------



## Whitigir

I hear that all elekit has similar headphone’s out designs with resistors .  So I have no doubt that they should be the same or somewhat close to what was measured


----------



## Beefy

Whitigir said:


> I hear that all elekit has similar headphone’s out designs with resistors .  So I have no doubt that they should be the same or somewhat close to what was measured


Measurements of the 8600 are very different.

But what is more important than just output impedance, is the balance of gain, impedance and noise. 4R out isn't too bad for low Z phones, but not if gain is +20dB and noise is approaching the milliwatt range.


----------



## EagleWings

I have not seen the schematic of the 8800, so can’t comment. But the resistor network for headphones of the 8600 is very different from the one on the 8900.


----------



## HiGHFLYiN9

From the other thread the impedance selections of the 8600 seemed a little strange:

Position 1 : 670Ω
Position 2 : 550Ω
Position 3 : 240Ω
Position 4 : 120Ω

...I'm assuming there's a lower impedance setting in the 8900?


----------



## Beefy (Oct 26, 2021)

HiGHFLYiN9 said:


> From the other thread the impedance selections of the 8600 seemed a little strange:
> 
> Position 1 : 670Ω
> Position 2 : 550Ω
> ...


From all accounts that is correct, the 8600 headphone out is bonkers. Completely unusable for anything except extremely high impedance phones, and only at the lowest impedance setting.

The 8900 should be considerably lower, like the 8800. But without solid measurements of gain vs output impedance at all the different settings, I'm still skeptical as to the utility for low impedance phones that require high damping factor.

@EagleWings, @Whitigir and I have also been posting over at DIY Audio starting here. Eaglewings was planning some great experiments here. My suggestion to measure gain and output impedance is in addition to those; between all that it should give us a complete picture.


----------



## Whitigir (Oct 29, 2021)

So, it has been a while.  Just to publish it here that I have solved the XLR balanced input by using Jensen transformers and eliminating the ground loops in both NFB and Non NFB alike.  Also benefiting from true balanced DAC sources as well

You can buy this Line Input from here
Very fast shipping!!


It comes with Wima capacitors and small resistors of recommended values.  However, I found that using Sprauge is giving me a much more pleasant tones for sub bass and lower mid bass.  Also do not use any resistors in series as I tried previously.  It actually doesn’t give a good performances, there will be sibilants.  This Sprauge Black Beauty from EBay is recommended, 400pF! The link is valid as of today


The schematic I used from the transformers itself is going like this

***Red is XLR Pin 2

***Brown is toward XLR Pin 3

***Then White Plus Black plus Orange are all going toward the Capacitor Cathode side, which is then going to Volume Control Ground directly

***Pin 1 is non connected toward anything

*********Yellow is toward resistor , and connecting toward L-in or R-in on Volume control .  Both L-in/R-in are *omitted* from connecting between VR (Volume Control) toward Motherboard.  *This means that the RCA input is no longer Valid*.  The Ground doesn’t need to be lifted away (plugged in) from the signals in order to enable XLR balanced input.



So the Transformers are being placed closest to the back with dual sided tapes, which fixed it so firmly, and that it ain’t going anywhere.  All connections are hot glued in order to insulate, with Kapton tapes to organize the extra length from the transformers.



The Jensen transformers will at first leaving a lot to be desired, like the sub bass would at first be non presenting, and after 10 hours or so, it will surface slowly, then the lower mid bass would be wooly and not under great control until 50 hours or so, and then beyond the 50 hours is where the upper mids and high extensions would start to show it textures.  The soundstage is absolutely taken to the maximum rendering from your very DaC source.  If I am using my Shanling M30 from it RCA previously VS the Jensen Balanced input, then the soundstage is vastly improved in width/depth and layering, with width, layering, separations, fidelity are all mostly preserved from the Source itself VS if I was to use RCA input.

At this point, I may not want to further experiment with other transformers at all as I have been burning in casually at over 150 hours by now.  Certainly am very happy with the TU-8900 and the modified input


----------



## HiGHFLYiN9

Jensen and Cinemag make very high quality transformers. Great choice.


----------



## JamieMcC

I meant to mention but forgot it took my V-Cap cutf's just over 300hrs before they settled down and lost that noticeable teflon sheen that new teflons seem to all have.


----------



## Whitigir

JamieMcC said:


> I meant to mention but forgot it took my V-Cap cutf's just over 300hrs before they settled down and lost that noticeable teflon sheen that new teflons seem to all have.


Wooottt!!! A long way to go lol


----------



## HiGHFLYiN9

JamieMcC said:


> I meant to mention but forgot it took my V-Cap cutf's just over 300hrs before they settled down and lost that noticeable teflon sheen that new teflons seem to all have.


Glad they're finally broken in!


----------



## JamieMcC (Nov 12, 2021)

HiGHFLYiN9 said:


> Glad they're finally broken in!



Me to,  while it was a only a small distraction  once you hear such traits it's very hard to unhear them every time you listen. The glare on the early saber chip based DACs being a good example.

I noticed some sonic impressions have been posted by Mavin86

https://redirect.viglink.com/?forma...ild-impressions-and-review.11541/#post-363207


----------



## Whitigir

That is a curse, to be able to tell the differences and not able to ignore it 😳💰💰💰😳


----------



## HiGHFLYiN9 (Nov 12, 2021)

JamieMcC said:


> I noticed some sonic impressions have been posted by Mavin86


It's interesting that people prefer the DNA Stratus generally to other more-costly-to-build amplifiers. Mavin seems to prefer it to the 8900, with the 8900 having very premium amorphous core OPTs, whereas the Stratus seems to have low-cost Edcors . Like the Gain Card, sometimes simpler is better I suppose.






It looks like each heater has it's own choke and filter PCB which is a nice touch.


----------



## JamieMcC (Nov 12, 2021)

HiGHFLYiN9 said:


> It's interesting that people prefer the DNA Stratus generally to other more-costly-to-build amplifiers. Mavin seems to prefer it to the 8900, with the 8900 having very premium amorphous core OPTs, whereas the Stratus seems to have low-cost Edcors . Like the Gain Card, sometimes simpler is better I suppose.
> 
> 
> 
> It looks like each heater has it's own choke and filter PCB which is a nice touch.




The Stratus certainly has a lot of fans but after seeing its internals the cost of ownership seems at odds with the components inside.

Hopefully Mavin will get hold of some 300B tubes and post another update after three or four hundred hours of runtime. I think it's definitely beneficial to get the run time up on this amp.

Curiously 2A3 combined with no negative feedback would be my least preferred combination. With the choice of 2A3 or 300B with or without feedback at hand. 

However I can honestly say listening with any of the combinations  is very enjoyable and having that variety as there are considerable differences between them is a massive plus for switching between genres and enjoying what you want to listen to how you like to listen with both headphones or speakers.

PS  @Maven86 thanks for sharing your thoughts on the amp I've enjoyed reading your write up on the build and sound impression having shared a many of those frustrations and elations along the way.

Definitely think you had a good handle on the overall sonics. 

Cheers


----------



## Maven86 (Nov 13, 2021)

HiGHFLYiN9 said:


> It's interesting that people prefer the DNA Stratus generally to other more-costly-to-build amplifiers. Mavin seems to prefer it to the 8900, with the 8900 having very premium amorphous core OPTs, whereas the Stratus seems to have low-cost Edcors . Like the Gain Card, sometimes simpler is better I suppose.
> 
> 
> 
> It looks like each heater has it's own choke and filter PCB which is a nice touch.


I think it's best that I clarify\elaborate a little more on what I meant in my comparisons.  As far as the Stratus goes, I tend to like how Donald voices his amps (I briefly owned a sonnet before the stratus) and for most of the time I prefer that signature.  If I had to choose between the Stratus, AF, and 8800, I'd probably go with the Stratus for the tone, but would still concede that it doesn't quite perform as well "technically" as the other 3 amps.  Despite not being able to compare it in my current system, I've heard it more than a few times on much better systems (than mine), and didn't think it scaled too much.

Comparing it to the 8900 would a be a very different situation.  I may still prefer the overall voicing of the Stratus but not by much, the 8900 is actually less "hifi" sounding than its predecessors, and the overall performance deficit is so large IMO, that I'd be more than willing to overlook the voicing in favor of the 8900.  If I were to make a similar analogy in terms of TVs, it would be like choosing between a 720P plasma with near perfect color reproduction (e.g. Pioneer Kuro Elite), or a modern 4K OLED with excellent color reproduction.

Now if you throw in the current Stratus, and by extension the Stellaris with the new AudioNote OPTs, I'd wager things might be different...

Also, in all of my scrambling around, I JUST realized who you are.  This is probably a good case for me needing a small vacation from work...  Anyway, the resistor box I purchased from you a while back has been a godsend.  Because of it, I've been able to take my Utopias and audition them with some very nice speaker amps over the course of the year.  It's been very helpful for getting reference points and figuring what to do for my next amp project (in the works).  Furthermore, I (greatly) prefer using the 8 ohm speaker outs with the box on my Elekit 8800, over the conventional headphone out.  So thanks for that....and also...the new Shin Megami Tensei is pretty awesome .


----------



## Maven86 (Nov 13, 2021)

JamieMcC said:


> The Stratus certainly has a lot of fans but after seeing its internals the cost of ownership seems at odds with the components inside.
> 
> Hopefully Mavin will get hold of some 300B tubes and post another update after three or four hundred hours of runtime. I think it's definitely beneficial to get the run time up on this amp.
> 
> ...


I appreciate the kind words Jamie.  I saw you mention the 400 hour break in before and since then I've been paying closer attention to see if I notice differences.  So far, if anything, it's been subtle after the 100 hour mark but perhaps it's because I'm using PIO caps instead of teflon.  

The feedback thing has been interesting.  A few more people came and listened over the last couple of weeks and 4\5 preferred NFB on, at least on my speaker setup.  I gave it another go for a couple of days and still couldn't really jive with it. I guess I'll settle for being the odd man out in this case.


----------



## Whitigir (Nov 13, 2021)

Maven86 said:


> I appreciate the kind words Jamie.  I saw you mention the 400 hour break in before and since then I've been paying closer attention to see if I notice differences.  So far, if anything, it's been subtle after the 100 hour mark but perhaps it's because I'm using PIO caps instead of teflon.  The feedback thing has been interesting.  A few more people came and listened over the last couple of weeks and 4\5 preferred NFB on, at least on my speaker setup.  I gave it another go for a couple of days and still couldn't really jive with it. I guess I'll settle for being the odd man out in this case.


I enjoy Non NFB rather than NFB.  To me, it is kinda similar to Oversampling Vs NOS.  The NFB yields better fidelity, extensions and details, but it compromises the realism, the tonal balances and the engaging feelings.

But when it comes down to nit and pick, NFB modes is better with 2A3 tubes where as the 300B is much better with Non NFB mode, and since I love WE300B.  I am constantly on Non NFB


----------



## Maven86

Whitigir said:


> I enjoy Non NFB rather than NFB.  To me, it is kinda similar to Oversampling Vs NOS.  The NFB yields better fidelity, extensions and details, but it compromises the realism, the tonal balances and the engaging feelings.
> 
> But when it comes down to not and pick, NFB modes is better with 2A3 tubes where as the 300B is much better with Non NFB mode, and since I love WE300B.  I am constantly on Non NFB


100% agree with the NFB analogy.  Couldn’t have said it better.


----------



## JamieMcC (Nov 13, 2021)

I had a rough estimate of hours run so far and it's definitely now over 500hrs I work from home and most days the amp gets turned  on between 7.30 & 8.00 am and stays on till 11 or 12pm.  If I go out for more than three or four hours and there's no one home it goes off but if it's just for a hour it two I tend to leave it on.

Probably 200 hrs of that on the 2A3 and 300 hrs on the 300b.

Lot of the time I just listen to ripped cd or Tidal via Roon but also regularly play favourite cds  (they just sound better than being streamed).  Also vinyl but only if I can sit and enjoy listening so not for background tunes maybe one evening a week if I'm lucky.

I switched over to listening to 300b without nfb this morning then returned to nf this afternoon I really enjoy both but the loss in resolution and more relaxed bass control for the range of genres I typically switch between is very noticeable.

However if I'm listening to say smooth jazz or female vocal then those differences are pretty minimal and the extra presence and tone of Non nfb is a great combination. 

On the other hand for such genres 2A3 is pretty spectacular with female vocal reproduction very beguiling it has I'm not sure how to describe it but maybe a crystalline clarity that sounds ethereal at times on good recordings. But male vocal like say Gregory Porter it's 300B all the way due to the gravitas and texture the 300b bass adds.

After 500hrs the only solid observation I have is there  is definitely not one tube or nfb setting to rule them all.

I'm very tempted to try the Duelund capacitors or the WE 300b reissue but undecided which to do first.  In the meantime some Duelund hook up wire has arrived and I'm going to rewire my speakers with it bypassing the banana plugs and soldering direct to the speaker tabs of the free range main drivers.


----------



## HiGHFLYiN9

JamieMcC said:


> The Stratus certainly has a lot of fans but after seeing its internals the cost of ownership seems at odds with the components inside.


Given it's hand-made in the U.S. it seems about normal, at least for this sector. I'd imagine the current pricing has much to do with supply vs. demand as well. While I don't have $4,300 in fun money to spare at the moment I can see how it would be worth the price of admission. 

@Maven86  thanks very much for further clarification on your impressions. I tend to prefer tone over technical performance as I'm looking more for emotional connection with my music vs. e.g. "the most clear highs" (similar to how Whigir feels about NFB), so I overly simplified your post based on my own preferences. I like the TV analogy  NFB I'm sure works better or worse depending on the whole systems voicing. 

It would be an interesting test to drop a pair of higher end OPTs in the Stratus from Heyboer/Electraprint/Cinemag ... or even Lundahls. I've always avoided the bargain Edcors as I read they didn't measure well but maybe that's just what the doctor ordered for realism. Jupiter caps supposedly don't measure well but I've always liked those. 

Glad you are enjoying the converter box  I've got a new emblem for those. PM me your address if you'd like one. 

I'm salty I didn't get the collectors edition of SMT, but I'll get over it eventually, lol  Super glad a next gen one is out.


----------



## Maven86 (Nov 14, 2021)

HiGHFLYiN9 said:


> Given it's hand-made in the U.S. it seems about normal, at least for this sector. I'd imagine the current pricing has much to do with supply vs. demand as well. While I don't have $4,300 in fun money to spare at the moment I can see how it would be worth the price of admission.
> 
> @Maven86  thanks very much for further clarification on your impressions. I tend to prefer tone over technical performance as I'm looking more for emotional connection with my music vs. e.g. "the most clear highs" (similar to how Whigir feels about NFB), so I overly simplified your post based on my own preferences. I like the TV analogy  NFB I'm sure works better or worse depending on the whole systems voicing.
> 
> ...


I think in essence we agree.  I'd take a much cheaper, emotionally engaging amp over a sterile 5 figure one with XYZ fancy transformers any day.  I guess what I was trying to say in all my ranting is that I find my 8900 more emotionally engaging than my old stratus.  It just does it in a different way.

As for NFB, like almost everything else, system synergy plays a significant role.  FWIW, I preferred the Elekit 8600 & 8800 over the the AF.  Both had NFB, the AF didn't...  Implementation and circuit matter, I've learned that very few things are black and white in this hobby. 

Interesting experience with the Edcors.  I recently sold a pair of 45 monoblocks that had some old 1960 Tamura transformers pulled out of a Sony tape deck.  According to some guys at DIYaudio, they were probably the worst measuring transformers of any tube amp I've probably owned so far....  It wasn't the most resolving, or the fastest amp I've heard but it had one of the most beautiful sounding tones of any I've heard so far (and I've heard a lot).  It was so engaging, that it compelled me to start up another project.  FME, I feel that after a certain acceptable threshold, measurements don't say much about whether or not you'll like the sound of something.

You and I are two in a very large crowd of salty people, it was pretty much impossible to get that special edition.  However...  My brother managed to pull a miracle and snag one before the scalpers so I guess prayers get answered lol.

@JamieMcC I vote for the Duelunds but not because I have any sort of selfish curiosity for how they compare to the V-caps  .


----------



## Whitigir (Nov 15, 2021)

HiGHFLYiN9 said:


> It's interesting that people prefer the DNA Stratus generally to other more-costly-to-build amplifiers. Mavin seems to prefer it to the 8900, with the 8900 having very premium amorphous core OPTs, whereas the Stratus seems to have low-cost Edcors . Like the Gain Card, sometimes simpler is better I suppose.
> 
> 
> 
> It looks like each heater has it's own choke and filter PCB which is a nice touch.


Well, it have come to the point that these components (OTs, Capacitors, resistors…etc… ) are not always the case of better specs, more expensive to automatically translated into a better performances machine.  This have come from since whenever people have discovered the reproduction of music !!!

That is why it is called “Acoustic tuning”.  I think one of the reason why people love tubes and rolling it is because personally, they can tune it to voice the way they desire the most from their stuff.

Back to the 8900!!! I love this amp!! It always leaves me speechless with it vast soundstage, depth, width and it even creates a further out projected soundscape for HD800/S/820 all alike.  Musical, warmth, and yet at high fidelity, there is no question it.

I love it so much that I don’t think I would need to change up anything else.  It is lovely the way it is.  The discussion of the output resistors and so on, did get to me a bit, but whenever I turn on the amp, all my doubt is gone away.


----------



## JamieMcC

First piece of what looks like it's going to be a in depth review with tube rolling impression on this Japanese site.  It auto translated for me.

https://tubeaudio.exblog.jp/30655505/


----------



## Whitigir

JamieMcC said:


> First piece of what looks like it's going to be a in depth review with tube rolling impression on this Japanese site.  It auto translated for me.
> 
> https://tubeaudio.exblog.jp/30655505/


Thanks!

This is significant for measurements for Non NFB, very wide bandwidth to begin with 



Also the DC that uses to feed the detection and bias circuits were measured to be in the mV range! That is pretty amazing.  Then again, with OTs, there should be no DC that is coupled into the output.  This explains why I love this amp so much!   Very powerful, and yet so clean, even for headphones


----------



## Maven86

JamieMcC said:


> First piece of what looks like it's going to be a in depth review with tube rolling impression on this Japanese site.  It auto translated for me.
> 
> https://tubeaudio.exblog.jp/30655505/


Nice find, those are some high profile tubes.  The Takatsuki 300Bs cost more than the amp itself...  I'm wondering if this build is with the stock OPTs, not sure if Elekit Japan also offers Lundahl?


----------



## petewebb

Hi All,

I'm currently building my 8900 and thinking of replacing some of the stock resistors with Texas Components TX2575 Naked metal foils. I used the TX2575's in a few places on my Bottlehead mainline, and they added a bit more detail/smoothness that I was impressed by.

I'm still in the early stage of learning to read and understand circuit diagrams/architecture in general,  but I was wondering if anyone had suggestions on which resistors in the signal path 8900 have the most impact on sound quality? Metal foils are pretty expensive, so I'd rather not have to replace a ton of the stock resistors if I don't have to. I'd likely be using the headphone out more than the speaker output if that makes a difference.

Any suggestions would be much appreciated!


----------



## HiGHFLYiN9

Hi Pete, thanks for joining the convo!  You may also want to roll in Audio Note non-magnetic Tantalums to see which you prefer before replacing additional resistors. Parts Connexion is currently having a 20% off sale FWIW. https://www.partsconnexion.com/audio-note-non-magnetic-resistors.html

I don't have the unit (yet) personally however I bet Whitiger can provide further insight regarding the resistors in the signal path given he's already digested the schematic to make some exciting improvements to take the circuit fully differential. 

Personally I've found resistors are usually on the lower end of the spectrum in terms of bang-for-the-buck upgrades. Transformers, potentiometer, tubes, and coupling caps would come first, so it would be good to know what upgrades you have already installed. In the middle are adding a choke or non-inductive wirewounds in the power supply, and upgrading electrolytics outside the power supply or bypassing with film. After that the minor items would be internal wiring, resistors, connectors, silver solder, etc. as you rapidly approach diminishing returns. Just my personal experience and to be taken with a grain of salt, as with DIY it's important to learn from personal experience. 

Great choice on the Elekit! It's a true Audiophile bargain. I hope you continue to build DIY in the future.


----------



## petewebb

Thanks HiGHFLYiN9, much appreciated. My first DIY adventure has been the Mainline, and the DIY blog on it over at Zynsonix(Yours?) was majorly inspirational for me. I even got myself a vintage Fender pilot light for it. 

Victor at VK mentioned the other day that he's getting some Audio Note sample resistors in this week for testing and would start offering them as an option 8900 upgrades soon, along with Audio Note capacitors. It sounded like he would sell the resistors at $3.50 each, which is a lot cheaper than the TX2575s at $10+ each, and parts-connection(who already has a ton of my money). I liked what the metal foils did for the mainline though, but I only listened to it stock for about a week, so not much of a break-in period.

For what I've upgraded so far:
I started the kit with mostly all Takman metal resistors that I bought in bulk a while back and finally got to use them. I got the kit with Amorphous core transformers and a set of V-Cap CutFs from Victor. I upgraded a few of the electrolytic caps with audio notes as well.  I've been following some of Whitiger's build notes already(which are superb), and upgraded to silver solid core wire and solder for signal paths and solid core copper for the rest. Some day I'll build up the nerve to attempt Whitiger's balanced input upgrades.  I also have a speaker tap to headphone output converter on order with Zynsonix. I got Sylvina 12BH7A's for tubes, though I'll probably use my Telefunken 12AU7s and already had some Western Electric 300Bs.


----------



## EagleWings (Dec 9, 2021)

I will give you the resistors for the left channel:

1. R102 - it is the only resistor in the signal path in the amplification stage.

2. Cathode resistors have shown to have an impact on the sound too, so; R103, R104, R108, R109, R110, R117, R118, R119.

3. If you plan on using the headphone out to drive your headphones, then; R123, R124, R125, R125, R126, R127, R128, R129. If you will be using speaker terminals, you can skip this.

4. If you plan on using the Negative Feedback (NFB), then; R121, 122, 123. If you don’t see yourself using NFB mode, you can skip this.

If I was planning on upgrading resistors in mine, I would simply do #1 and #2, as I have skipped all the resistors in the headphone circuit and don’t use NFB mode.


----------



## Whitigir

HiGHFLYiN9 said:


> Hi Pete, thanks for joining the convo!  You may also want to roll in Audio Note non-magnetic Tantalums to see which you prefer before replacing additional resistors. Parts Connexion is currently having a 20% off sale FWIW. https://www.partsconnexion.com/audio-note-non-magnetic-resistors.html
> 
> I don't have the unit (yet) personally however I bet Whitiger can provide further insight regarding the resistors in the signal path given he's already digested the schematic to make some exciting improvements to take the circuit fully differential.
> 
> ...


These highlighted are all very solid points.  It is much better to upgrade your  transformers and the internal wirings.

The internal wirings is very important to this particular kit amp.  Because this is not a 2 sided PCB.  Usually they are through holes, as there are cylindrical traces for those holes.  Your components legs will make contact as long as you solder it typically.  This TU-8900 doesn’t have those traces.  There are a bit play off tolerances to the Pads and the components legs.  You will not make good contacts on a basis of 70/30%.  So, I recommend anyone to use solid silver wirings, follow the schematic and do points to points wirings instead.

The resistors are from Xicon I believe, and that should already be of great quality by itself.  But if you want to upgrade them, follows what was posted above , the 1 series is Left and 2 series is R channel


----------



## petewebb

EagleWings said:


> I will give you the resistors for the left channel:
> 
> 1. R102 - it is the only resistor in the signal path in the amplification stage.
> 
> ...



Thanks EagleWings, This is extremely helpful!


----------



## petewebb

Whitigir said:


> These highlighted are all very solid points.  It is much better to upgrade your  transformers and the internal wirings.
> 
> The internal wirings is very important to this particular kit amp.  Because this is not a 2 sided PCB.  Usually they are through holes, as there are cylindrical traces for those holes.  Your components legs will make contact as long as you solder it typically.  This TU-8900 doesn’t have those traces.  There are a bit play off tolerances to the Pads and the components legs.  You will not make good contacts on a basis of 70/30%.  So, I recommend anyone to use solid silver wirings, follow the schematic and do points to points wirings instead.
> 
> The resistors are from Xicon I believe, and that should already be of great quality by itself.  But if you want to upgrade them, follows what was posted above , the 1 series is Left and 2 series is R channel


Thankfully I read through all your build notes posts prior to starting and used Mundorf Silver/Gold solder, which was about as good as I could find. Got some pure silver solid core and copper core wire coming in today, so I can finally get the Lundahl AC's and TDK pot all hooked up. I've super excited as I'm getting close to getting to try this thing out!


----------



## HiGHFLYiN9

petewebb said:


> Thanks HiGHFLYiN9, much appreciated. My first DIY adventure has been the Mainline, and the DIY blog on it over at Zynsonix(Yours?) was majorly inspirational for me. I even got myself a vintage Fender pilot light for it.


That'sa me  Glad you enjoyed the blog. I have a few new entries to post but time has been pretty tight. Those Fender pilot lights just really embody that vintage look. Moth Audio was very inspirational to me, the facets they employed in their designs were really appealing... kinda like Victorian-era steampunkish. I think your box is going out in the next week or two. EAR is having supply chain problems with their feet but I'll hit you up about it offline, there's a good sub.

There are plenty of very smart fellows on this thread with great advise. Honestly it feels a bit like old school HeadFi in here. Hopefully the DIY forums will pick back up again!

Regarding the resistors, Viktor is great about passing along substantial discounts on the parts he has. I haven't tried the metal films you are using so I'd be interested if you were able to do a comparison. Haha, I shudder to think how many thousands I've given to PCX  Chris has an awesome variety of stuff though. HiFiCollective is pretty good too, especially for fancy speaker inductors as PCX doesn't really stock those.


----------



## JamieMcC

Well what's to say, my TU-8900 seems to be sounding better than ever I'm long past the point where I was listening intently to the amp and am now just enjoying playing music .

 After spending a week enjoying listening with the 300b with no negative feed back I decided to swap the 300b's out and revisit running 2A3 with no feedback. This combination I've tried several times before and it's a combo that to be honest has never really gelled for me. 

Surprise surprise I've been revelling in the sonic landscape its been painting for the last week. Every now and then as I play through familiar tracks it serves up a soundscape that makes me pause in what ever I'm doing whilst I savour in equal measures of amazement and disbelief at the deliciousness of the moment.


----------



## toobuzz

I've been following this same cast of characters through this form and others.  I love reading through your adventures and you've all been very helpful to me along the way.

I've had the TU-8900 (amorphous Lundahl and VCap CuTf) for several months now.  I love this thing so much, and I agree with everyone's opinions especially regarding NF/Non-NF.  For my system and my tastes Non-NF is how I prefer to listen.  I usually use the Linlai/Cossor WE2A3, but I often swap in the Gold Lion 300B (out of my Bottlehead BeePre from my main system).  Both are just awesome, however there is something about the WE2A3 (and perhaps the amorphous OPT?) that seems to sweetens up everything, like it's been dipped in caramel or something. 

On a more objective topic, can someone help me make sense of the headphone options?  The resistor network options certainly change the power output, I get that.  I get that the output impedance also changes.  I don't really care much about the power specs, but I'd like to see if it is possible to calculate the output impedance for each jumper setting?


----------



## EagleWings

@toobuzz I tried asking 2 of my friends who have an electrical background and even they didn’t know how to calculate the output impedance of the 8900’s jumper positions. What makes it complicated is the second set of those shunt resistors (R226, 227, 228 and 229).


----------



## JamieMcC

With my hd800 I started off on the highest
impedance setting later moving to the middle setting and around two weeks ago moved to the lowest position of the thee hi, med,  low, option available in that hi range.

*For me* this is my preferred setting so far. But I'm open to the possibility the highest of the low setting options might be good as well. I just haven't got there to give it a try yet.


----------



## toobuzz (Dec 22, 2021)

@EagleWings, thanks for the effort, I suppose we would need proper test equipment to determine the actual values.

There are 5 positions for the jumpers, right? I suppose it was unsettling to see that the “Hi Imp/Low Output” is the same as the “Low Imp/High Output”.

I use the HD800 and HEDDphone on the 8900 on the “Low Imp/High Output” setting. Knowing what happens with the HD800 on the Mainline when I switch between Hi/Low impedance I expected the 8900 to also display a similar difference. Not so much in my experience. It’s almost more about usable volume pot travel (especially in non-NF mode) than anything else.

@JamieMcC, it looks as if we,be settled on the same setting for the HD800!

I’ve been listening to speakers much more these days. I picked up a pair of Omega Super 3 XRS and my goodness, the 8900 is able to show its beauty on these.


----------



## JamieMcC (Dec 22, 2021)

@toobuzz probably a good sign we have both settled on the same setting (ps I'm also a Mainline owner).

I've very nearly pushed the button a couple of times on a pair of the Omega SAMs but they are significantly more here in the UK. I've heard feedback from a couple of Chord Dave owners who drive them direct from the Dave DAC no amp (2W) one also has spendy hi end Bowers and Wilkins 803 D3 (£13k here in the UK) if I remember correctly and he just gushes about the Omega's 

There was some interesting discussion recently on the Bartok thread  where one of the Uber hi end gurus said they sold off most of their hi end cans abyss, utopia, lcd4, and susvara in favour of his long standing hd800 with sdr mod as he came to the conclusion the hd800 SDR has technical prowess that he believed the other cans could not match.

"There are headphones that sound almost as good technically but presented in a more enjoyable signature but really isn't much improvement beyond hd800 in terms of technical performance."

Its not the first time I've seen such comments from those with deep pockets and it's such comments  that have kept me with the hd800 rather than chase rainbows on the latest flavor of the moment.


----------



## Maven86

toobuzz said:


> @EagleWings, thanks for the effort, I suppose we would need proper test equipment to determine the actual values.
> 
> There are 5 positions for the jumpers, right? I suppose it was unsettling to see that the “Hi Imp/Low Output” is the same as the “Low Imp/High Output”.
> 
> ...


+1 on the Omega\8900 pairing.  Honestly, I wasn’t really blown away by the Omegas before, and they ended up on the shelf for a while.  One day I put them back in to audition for a potential seller...  Thankfully he backed out because these never came off the stands after that. 

The pairing was magic.  Sound was extremely transparent and very “real” sounding.  Full rangers aren’t known for reproducing the tail end frequencies very well but damn did they fool me into believing they did.  These rocked the room from top to bottom.  System synergy is very underrated.


----------



## Beefy (Dec 22, 2021)

EagleWings said:


> @toobuzz I tried asking 2 of my friends who have an electrical background and even they didn’t know how to calculate the output impedance of the 8900’s jumper positions. What makes it complicated is the second set of those shunt resistors (R226, 227, 228 and 229).





toobuzz said:


> @EagleWings, thanks for the effort, I suppose we would need proper test equipment to determine the actual values.
> 
> There are 5 positions for the jumpers, right? I suppose it was unsettling to see that the “Hi Imp/Low Output” is the same as the “Low Imp/High Output”.
> 
> ...



It's relatively simple to measure total output impedance, you just need a low impedance dummy load (an 8-32 ohm resistor at appropriate wattage would be ideal), a multimeter that gives accurate AC voltage readings, and a good test tone (I use a 50Hz 0dB signal).

Set amp to a loud volume, but below clipping. Measure amp voltage output with no load connected, then with the dummy load connected, then calculate output impedance. One of the answers in this page has the formula: https://electronics.stackexchange.com/questions/6917/measuring-output-impedance

Bonus points for anyone who does this, if they can also measure the unloaded and loaded gain. You would do this by measuring the input voltage just after the potentiometer, then (un)loaded output voltage divided by input voltage.


----------



## EagleWings (Dec 23, 2021)

@toobuzz and @Maven86 , those are some beautiful Omegas. It would have probably been my speaker of choice, was I in the US. So, after seeing comments on DIYA forum and hearing from my friends about, how great the 8600/8900 work on speakers and, because I am smitten by the sound of the 8900, I couldn't resist and picked up a pair of Lii F15 drivers, to build a simple open baffle. I also have a pair of Graham LS6, which supposedly works decently on a 300B amp in nearfild. But I haven't tried it yet, nor have I finished the building the OB for the Liis. But I am super excited to about it.

@JamieMcC , me and my friends are big fans of DHT amps, and after exploring other headphones, we have come full circle, back to Senns. While I explored planars only briefly, some of my buddies went knee deep into the planar realm, only to realise our heart lies with DD + DHT. While they found a couple of non-Senn DDs that were quite interesting, they figured those headphones too had some serious compromises, which was quite unacceptable for the asking price. So we all have come back to the Senns and are quite impressed at how well these headphones scale, when driven by a good tube amp, fed by a good DAC. Utopia is probably the only headphone I am still curious about that, I would love to own one at some point to see how it works in the long term.

@Beefy , thanks for this info. I can't measure the OI of various jumper positions in mine, as I have literally skipped all the resistors in the headphone resistor network. So the headphone out on my 8900 is equivalent to the speaker taps. But I will keep this in mind, in case I install the resistors in future to try em out.


----------



## Beefy

EagleWings said:


> @Beefy , thanks for this info. I can't measure the OI of various jumper positions in mine, as I have literally skipped all the resistors in the headphone resistor network. So the headphone out on my 8900 is equivalent to the speaker taps. But I will keep this in mind, in case I install the resistors in future to try em out.



In some ways, your measurements would almost be the most important... What is the output impedance under a best case scenario aiming for low output impedance? What is the amp gain under these conditions?


----------



## Maven86

EagleWings said:


> @toobuzz and @Maven86 , those are some beautiful Omegas. It would have probably been my speaker of choice, was I in the US. So, after seeing comments on DIYA forum and hearing from my friends about, how great the 8600/8900 work on speakers and, because I am smitten by the sound of the 8900, I couldn't resist and picked up a pair of Lii F15 drivers, to build a simple open baffle. I also have a pair of Graham LS6, which supposedly works decently on a 300B amp in nearfild. But I haven't tried it yet, nor have I finished the building the OB for the Liis. But I am super excited to about it.
> 
> @JamieMcC , me and my friends are big fans of DHT amps, and after exploring other headphones, we have come full circle, back to Senns. While I explored planars only briefly, some of my buddies went knee deep into the planar realm, only to realise our heart lies with DD + DHT. While they found a couple of non-Senn DDs that were quite interesting, they figured those headphones too had some serious compromises, which was quite unacceptable for the asking price. So we all have come back to the Senns and are quite impressed at how well these headphones scale, when driven by a good tube amp, fed by a good DAC. Utopia is probably the only headphone I am still curious about that, I would love to own one at some point to see how it works in the long term.
> 
> @Beefy , thanks for this info. I can't measure the OI of various jumper positions in mine, as I have literally skipped all the resistors in the headphone resistor network. So the headphone out on my 8900 is equivalent to the speaker taps. But I will keep this in mind, in case I install the resistors in future to try em out.



Yea, I'm pretty much at the same point. Tried a lot of setups and always went back to DHTs + dynamics.  I've bought and sold the HD650s more times than I can count.  It's easily the headphone I've held the longest in some iteration or form...probably for good reason.  Can't say I've found anything better when it comes to tone and timbre, and like you said, it scales like mad with better setups (almost shockingly), and seems to have very good synergy with Elekits across the board. 

I like the Utopia for other reasons.  My initial impressions were actually very negative and I avoided it like that plague for many years.  IMO, it's a headphone that's hard to get right and is very much a chameleon depending on its source.  Probably why the impressions I've seen have been so diverse.  As good as the 8900 is with it, which is very good, it can get much better.  On the best setups I've tried, it's the closest thing to an ideal headphone I've heard.  It's almost paradoxical in that the a lot of the common shortcomings attributed to it (narrow\closed stage, rough treble, analytical, light bass) become some of its greatest strengths.  In one of these systems, the stage had so much dimensionality on one recording, that I thought the DAC got disconnected...and sound was coming from the computer speakers in front.  Treble was life like without a hint of glare.  On the right recordings, the bass was dynamic, textured, and rattled ears.  Extremely engaging, with just about any genre I threw at it.  

@JamieMcC Your comments on the HD800 turned a few cogs in my head.   Years back I briefly played around with one, but it never jived with me despite everything I tried at the time.  Lately however, I can't shake off this gut feeling that I didn't quite give it a fair shot and that things might be very different with what's available now.  Will definitely give it an encore in the near future.


----------



## jamato8

Maven86 said:


> Yea, I'm pretty much at the same point. Tried a lot of setups and always went back to DHTs + dynamics.  I've bought and sold the HD650s more times than I can count.  It's easily the headphone I've held the longest in some iteration or form...probably for good reason.  Can't say I've found anything better when it comes to tone and timbre, and like you said, it scales like mad with better setups (almost shockingly), and seems to have very good synergy with Elekits across the board.
> 
> I like the Utopia for other reasons.  My initial impressions were actually very negative and I avoided it like that plague for many years.  IMO, it's a headphone that's hard to get right and is very much a chameleon depending on its source.  Probably why the impressions I've seen have been so diverse.  As good as the 8900 is with it, which is very good, it can get much better.  On the best setups I've tried, it's the closest thing to an ideal headphone I've heard.  It's almost paradoxical in that the a lot of the common shortcomings attributed to it (narrow\closed stage, rough treble, analytical, light bass) become some of its greatest strengths.  In one of these systems, the stage had so much dimensionality on one recording, that I thought the DAC got disconnected...and sound was coming from the computer speakers in front.  Treble was life like without a hint of glare.  On the right recordings, the bass was dynamic, textured, and rattled ears.  Extremely engaging, with just about any genre I threw at it.
> 
> @JamieMcC Your comments on the HD800 turned a few cogs in my head.   Years back I briefly played around with one, but it never jived with me despite everything I tried at the time.  Lately however, I can't shake off this gut feeling that I didn't quite give it a fair shot and that things might be very different with what's available now.  Will definitely give it an encore in the near future.


The only way I like the HD650 is balanced. Their character, for me, totally changes. Single ended even out of my good home amps, just doesn't make it. Balanced, it is a different headphone.


----------



## smodtactical

For you guys running the 8600.. what tubes do you like for a thicker warmer tilt?


----------



## JamieMcC




----------



## HiGHFLYiN9

Excitingly I believe Viktor will be able to supply a 8900 kit for me soon with V-Caps and amorphous core Lundahls. I'm thrilled to finally be joining you guys! I think the 8900 vs the HA-300 will be a comparo to go down in the books. Granted the HA-300 hasn't been as reliable as I'd like it to be but I'm 100% certain Cayin put far more thought and effort into the manufacture than just churning out a product, and it's a great exercise in amp making (perhaps the pinnacle 300B headphone amp out of China). The 8900 is probably the finest DIY headphone amplifier on the market and is the epitome of a performance-forward efficient design, specifically with Viktor's additions. While the Cayin wins in the visual department, I think they will be similarly matched sound-wise. Stay tuned for the throw-down.


----------



## JamieMcC

HiGHFLYiN9 said:


> Excitingly I believe Viktor will be able to supply a 8900 kit for me soon with V-Caps and amorphous core Lundahls. I'm thrilled to finally be joining you guys! I think the 8900 vs the HA-300 will be a comparo to go down in the books. Granted the HA-300 hasn't been as reliable as I'd like it to be but I'm 100% certain Cayin put far more thought and effort into the manufacture than just churning out a product, and it's a great exercise in amp making (perhaps the pinnacle 300B headphone amp out of China). The 8900 is probably the finest DIY headphone amplifier on the market and is the epitome of a performance-forward efficient design, specifically with Viktor's additions. While the Cayin wins in the visual department, I think they will be similarly matched sound-wise. Stay tuned for the throw-down.


That's great news to hear.  Have you any plans to venture from the standard construction some of your past builds have been very creative.


----------



## Maven86

HiGHFLYiN9 said:


> Excitingly I believe Viktor will be able to supply a 8900 kit for me soon with V-Caps and amorphous core Lundahls. I'm thrilled to finally be joining you guys! I think the 8900 vs the HA-300 will be a comparo to go down in the books. Granted the HA-300 hasn't been as reliable as I'd like it to be but I'm 100% certain Cayin put far more thought and effort into the manufacture than just churning out a product, and it's a great exercise in amp making (perhaps the pinnacle 300B headphone amp out of China). The 8900 is probably the finest DIY headphone amplifier on the market and is the epitome of a performance-forward efficient design, specifically with Viktor's additions. While the Cayin wins in the visual department, I think they will be similarly matched sound-wise. Stay tuned for the throw-down.


Congrats!  Looking forward to your impressions.


----------



## toobuzz

HiGHFLYiN9 said:


> Excitingly I believe Viktor will be able to supply a 8900 kit for me soon with V-Caps and amorphous core Lundahls. I'm thrilled to finally be joining you guys! I think the 8900 vs the HA-300 will be a comparo to go down in the books. Granted the HA-300 hasn't been as reliable as I'd like it to be but I'm 100% certain Cayin put far more thought and effort into the manufacture than just churning out a product, and it's a great exercise in amp making (perhaps the pinnacle 300B headphone amp out of China). The 8900 is probably the finest DIY headphone amplifier on the market and is the epitome of a performance-forward efficient design, specifically with Viktor's additions. While the Cayin wins in the visual department, I think they will be similarly matched sound-wise. Stay tuned for the throw-down.


Congrats!  Did you order any tubes from Victor?  What tubes are planning to use?


----------



## HiGHFLYiN9

Depending on how much I like the finish I may or may not powdercoat it and/or polish the front panel. Other than that, non-magnetic resistors, maybe some Mills wirewound resistors... the volume pot looks chintzy, what are you guys using there? I'd like to get a TKD if it fits. 

For 300B I have Shuguang treasures, EH gold and Gold Lion to try. I need to find some 2A3.


----------



## EagleWings (Jan 14, 2022)

Victor sells the TKD 601 pot. It’s better than the stock, but still meh. I thought about putting in a TKD 2511 or a Khozmo attenuator. But I realized it would not be possible given the position of the hole for pot’s shaft and clearance between the pot and the main PCB. I plan on getting an external Slagle Autofomer Vol Ctrl and bypassing the internal pot sooner or later.

P.S: I look forward to your Cayin vs Elekit comparison.


----------



## jamato8

HiGHFLYiN9 said:


> Depending on how much I like the finish I may or may not powdercoat it and/or polish the front panel. Other than that, non-magnetic resistors, maybe some Mills wirewound resistors... the volume pot looks chintzy, what are you guys using there? I'd like to get a TKD if it fits.
> 
> For 300B I have Shuguang treasures, EH gold and Gold Lion to try. I need to find some 2A3.


Mills are a good choice but, have an inductive resistor actually provides some filtering. There is little room for a larger volume control. I asked about it and DACT or the likes can not be used, due to room. The Alps isn't bad at all but for sure, I would like, if I purchased the kit, to be able to put in a higher quality pot.


----------



## HiGHFLYiN9

Jamato it's been a while, I didn't realize you were still on here. We had fun modding our Woo Audio amps back in the day. I see you have some Linear Tube Audio gear; great stuff. 

That's too bad about the pot clearance but the TKD 601 is probably good enough. I've grown so tired of seeing the Alps Blue Velvet (or Chinese knockoff) in every amplifier that honestly anything else is preferable at this point. The Slagle Autofomers and other TVCs are a novel way to adjust volume, I'd love to hear your impressions if you go that route EagleWings. I've had something similar in my ebay cart for a while now but never bit the bullet.


----------



## jamato8

HiGHFLYiN9 said:


> Jamato it's been a while, I didn't realize you were still on here. We had fun modding our Woo Audio amps back in the day. I see you have some Linear Tube Audio gear; great stuff.
> 
> That's too bad about the pot clearance but the TKD 601 is probably good enough. I've grown so tired of seeing the Alps Blue Velvet (or Chinese knockoff) in every amplifier that honestly anything else is preferable at this point. The Slagle Autofomers and other TVCs are a novel way to adjust volume, I'd love to hear your impressions if you go that route EagleWings. I've had something similar in my ebay cart for a while now but never bit the bullet.


The Alps stock pot is the little one. Not the Blue Velvet like Quicksilver uses in all of their gear. I assume that is the one you refer to. I like that they have the amorphous output transformers available. That is what I would go with.


----------



## petewebb

Hi All,

I got my 8900 all assembled and have been burning it in for a few weeks at this point. I absolutely love it. The build itself was pretty smooth. The only issues I had were that crazy “L” shaped joint connecting unit-4 to the speaker terminal board, OMG what a pain to solder until I discovered I could use alligator clips to keep the pins in place while I soldered them. Also unfortunately had a manufacturing issue with the chassis itself, where the front half of the chassis was ben inward toward the middle of the unit and the volume board and front faceplate wouldn't fit properly, but Victor was kind enough to swap it out for me and all fits fine now.

Things I added to the build:


Replaced 100uF and 47uF electrolytic caps with AudioNote standards, and the 6800uF with Nichicon KA’s
Used Z-foil naked resistors for most of the cathode, headphones and NFB positions. For the 2x signal amplification resistors and the 2x 15uF positions I used AudioNote  Niobium Non-Magnetic resistors. AutoNote standard for the rest of the 220Ks. Thankfully I was able to take advantage of holiday sales.
Used Ohmite AGs 270uF 5w resistors. Started off with Kiwame’s but switched them out as I’ve heard good things about the Ohmite AG series.
Started off using the VCap CuTF caps I got from victor but switched them out for Duelund 0.1uF 630Vdc CAST-PIO-Ag's and had to custom rig with heat-resistant zip ties and pads, silver wire and WAGO lever nuts(so I can take the board out if needed).
Used pure silver wire to connect volume PCB to the mainboard. (thanks for the tip Whitigir)
I used Mundorf silver/gold solder for all the audio path components, but honestly, that stuff is a huge PITA and I would rather saw my own arm off than use it again. It’s nearly impossible to get a shiny proper joint with that stuff at any heat setting. The WBT silver/lead stuff is so much easier to use.

After I completed the main build, all the LEDs came green on the first try, which was a relief. I’ve been burning in the unit for just over 75hours now with 2A3s and 12AU7s, with some periods of listening with WE300B and 12BH7As with NFB on and off. I think I prefer the non-NFB mode and the 12BH7As, but still haven’t made up my mind between the 2A3s and WB300B (they both sound awesome).

Overall I’m super happy with the TU-8900. It was a pleasure to build and sound is out of this world. Much different than my Mainline for sure. Now I’m just waiting for Jensen JT-11P-1’s to come back in stock, and I’ll try the balanced XLR input mod.

In the meantime, I got ahold of a completely original and in great shape Dynaco ST-70 from the original owner. Starting the super fun research into restoring and upgrading it. This DIY stuff is definitely addictive!


----------



## HiGHFLYiN9

Very cool Pete, congrats on all the fun upgrades. Be careful with the Dynaco, that is a HUGE rabbit hole with more mods than you can count  If you need spare parts reach out to Kevin at Dynakit Parts. All of his stuff is immaculately made.


----------



## hikaru12

Poured through this thread - seems like Elekit offers a lot of flexibility especially considering the case size on cap upgrades, etc. Has anyone ever compared it to the ZMF Pendant?


----------



## HiGHFLYiN9

ZMF Pendant uses indirectly heated EL84 tubes so the harmonics are going to be quite different. EL84s amps are generally pretty crisp and detailed sounding. I still have my Budgie SE so I could compare that when the 8900 is done. The ZMF has a rectifier tube and probably other tweaks, but I believe the circuit is similar. On paper DHTs are inferior although most tube enthusiasts like the additional "tubiness" that they bring to the table. They are expensive, microphonic, and usually require further efforts to reduce noise within the circuit, but they are more syrupy and warm sounding. A better indirectly heated tube to compare to the 300B is the EL34 which has a similar midrange "magic" imho. Unfortunately there are few EL34 based headphone amps, however there are many EL84 amps, I'd assume because two EL84s can handle very adequate power for most headphones. 

If you like the DIY route, Audio Note Kits has an EL84 based headphone amplifier and you get *really good* parts for your money: https://ankaudiokits.com/product/headphone-virtuoso-el84/ ...Brian is friendly and very responsive although it can sometimes take him a bit to get you all the parts for the build. Many of the premium parts people are upgrading here come standard with the Virtuoso. I'd personally buy one but I need another amp like I need a hole in the head   

For whatever it's worth, and to be taken with much salt as everyone has different preferences, but the best system I ever heard was powered by 300Bs.


----------



## Maven86

petewebb said:


> Hi All,
> 
> I got my 8900 all assembled and have been burning it in for a few weeks at this point. I absolutely love it. The build itself was pretty smooth. The only issues I had were that crazy “L” shaped joint connecting unit-4 to the speaker terminal board, OMG what a pain to solder until I discovered I could use alligator clips to keep the pins in place while I soldered them. Also unfortunately had a manufacturing issue with the chassis itself, where the front half of the chassis was ben inward toward the middle of the unit and the volume board and front faceplate wouldn't fit properly, but Victor was kind enough to swap it out for me and all fits fine now.
> 
> ...


Wow...  That's probably the most tricked out Elekit I've seen so far.  How was the switch from the V-Caps to the Duelund?  Was always curious to compare the two but didn't want to deal with the hassle of another week long burn in.


----------



## JamieMcC

Where are you guys sourcing your 0.1uf AG Duelunds?


----------



## petewebb

Maven86 said:


> Wow...  That's probably the most tricked out Elekit I've seen so far.  How was the switch from the V-Caps to the Duelund?  Was always curious to compare the two but didn't want to deal with the hassle of another week long burn in.


So far I only have about 25hrs on the Duelunds, and they sound a bit more neutral than the V-Caps. My setup is already pretty neutral sounding due to the Z-Foil resistors I used. I'm going to switch the caps around again this weekend, so I'll let you know.


----------



## petewebb

JamieMcC said:


> Where are you guys sourcing your 0.1uf AG Duelunds?


Got mine at Partsconnexion: https://www.partsconnexion.com/duel-cast-au630v.html


----------



## Maven86

JamieMcC said:


> Where are you guys sourcing your 0.1uf AG Duelunds?


Private sales and partsconnexion when on sale.  If you're in the UK I think Hificollective might be better:

https://www.hificollective.co.uk/catalog/castdcag010-01uf-630v-duelund-cast-silver-stock-p-9417.html


----------



## hikaru12

So can any of you guys build me a kit? There’s a guy on Etsy who will do it for $500 but don’t know if that’s a fair price given the relative simplicity in putting this together. I just suck at soldering lol


----------



## jamato8

hikaru12 said:


> So can any of you guys build me a kit? There’s a guy on Etsy who will do it for $500 but don’t know if that’s a fair price given the relative simplicity in putting this together. I just suck at soldering lol


Seems high to me. I don't remember the house to build but say 8 hours, and I think it is less, at 50 dollars an hour that would be 400. Seems it could be less. Maybe the company that sells the kit also will do a build. I think I read they do and then everything would be tested for you as well.


----------



## Maven86

hikaru12 said:


> So can any of you guys build me a kit? There’s a guy on Etsy who will do it for $500 but don’t know if that’s a fair price given the relative simplicity in putting this together. I just suck at soldering lol


Try contacting Victor, I believe he’s building kits for a few people now.


----------



## HiGHFLYiN9 (Jan 15, 2022)

hikaru12 said:


> So can any of you guys build me a kit? There’s a guy on Etsy who will do it for $500 but don’t know if that’s a fair price given the relative simplicity in putting this together. I just suck at soldering lol


Is that the guy that builds Bottlehead kits?

It's going to be somewhat dependent on where you live and the cost of living. An experienced professional costs about as much as a mechanic. Here in the DMV area the cost for a solder slinger/amp repair is about $45-90 an hour depending on experience and may have a minimum "bench" fee. You may be able to find someone that can do it for less in their basement, but make sure they have some feedback! 

Also, *does anyone have a digital copy of the BoM?* I wanted to look it over. Viktor is waiting on some VCaps before my order can ship.



> So far I only have about 25hrs on the Duelunds, and they sound a bit more neutral than the V-Caps. My setup is already pretty neutral sounding due to the Z-Foil resistors I used. I'm going to switch the caps around again this weekend, so I'll let you know.


Pete those V-Caps can take 500 hours to settle in, so make sure to give them a fair shake before settling with the Duelund. Both are obviously very good caps though.


----------



## petewebb (Jan 15, 2022)

HiGHFLYiN9 said:


> Is that the guy that builds Bottlehead kits?
> 
> It's going to be somewhat dependent on where you live and the cost of living. An experienced professional costs about as much as a mechanic. Here in the DMV area the cost for a solder slinger/amp repair is about $45-90 an hour depending on experience and may have a minimum "bench" fee. You may be able to find someone that can do it for less in their basement, but make sure they have some feedback!
> 
> ...


I'll DM you the BoM.

I'll definitely give the V-Caps more time. I accidentally bought 2 sets of them (one from victor and one directly). I was thinking of putting the spare set in the Mainline in place of the .1uFs there but I don't think it would do anything but make the underside of the chassis more pretty.


----------



## JamieMcC (Jan 16, 2022)

petewebb said:


> I'll DM you the BoM.
> 
> I'll definitely give the V-Caps more time. I accidentally bought 2 sets of them (one from victor and one directly). I was thinking of putting the spare set in the Mainline in place of the .1uFs there but I don't think it would do anything but make the underside of the chassis more pretty.



Fwiw on my own Mainline which I built in 2015 I had installed RTI 10uf tin foil teflons for the output capacitors.  In 2020 I thought I would give the 0.01 Duelund silver foil bypass caps a go.  I was expecting some small improvement but in all honesty the silver foil Duelund bypass caps made the largest step change in sonics I've ever experienced in installing a capacitor.

I have since transplanted them onto the Vcap cutf in my TU-8900

I would echo the requirement for 400-500 hrs of burn in with the Vcaps and the AM transformers. 

Both the Cossor WE2A3 & WE300B tubes purchased new from Victor with the amp took about 100hrs before settling down and coming on song.


----------



## jamato8

JamieMcC said:


> Fwiw on my own Mainline which I built in 2015 I had installed RTI 10uf tin foil teflons for the output capacitors.  In 2020 I thought I would give the 0.01 Duelund silver foil bypass caps a go.  I was expecting some small improvement but in all honesty the silver foil Duelund bypass caps made the largest step change in sonics I've ever experienced in installing a capacitor.
> 
> I have since transplanted them onto the Vcap cutf in my TU-8900
> 
> ...


Some don't get the need for forming the caps etc., which has been an ongoing debate for years. But it has been shown that chemically and the electrical properties of even PCBs change, which is why glass boards are so nice. Also why Black Gates often got a poor rap, because they didn't sound spectacular and it was not believed by many, that they needed up to 800 hours to burn in and would deform some, when not used and the process had to be started again, taking 100 to 200 hours. Audio Note UK, even suggested always having a charge on them, so they maintained the forming and best performance, which I agree with. 

The Duelund silver foil, when a cap in the signal path is needed, would seem to be a very fine choice, at a price of course.


----------



## HiGHFLYiN9

I was looking at possible cap upgrades in the power supply and saw the price of those Audio Note Kaisei; $228 for a single 100uf 500v electrolytic. I'm not sure a lot of those will sell at that price


----------



## petewebb (Jan 17, 2022)

HiGHFLYiN9 said:


> I was looking at possible cap upgrades in the power supply and saw the price of those Audio Note Kaisei; $228 for a single 100uf 500v electrolytic. I'm not sure a lot of those will sell at that price


The Kaisei caps won't fit the TU-8900. As it is the standard AN 100uFs just barely fit, I had to use longer leads on a few resistors to make room for the 100uFs.  The 6800 uF's are really small too, I think they are 16mm wide in a very cramped area which is a shame as I had some really nice Nichicon KGs I wanted to use there.

but yeah those non-polar Kaisei are crazy expensive.


----------



## HiGHFLYiN9

I saw you had to creatively mount the snap-in 50uFs (looks very good), didn't realize the resistors had to be moved for the 100uFs. There is real estate back there if you really wanted to fit larger caps, you'd just need to mount them sideways to the board and run leads. There's a lot of dual section caps out there (50uF + 50uF, 100uF + 100uF) so plenty of options. Jensen and Mundorf are both solid choices. The Unicon might be a little too large... those are more for old school builds with the caps protruding from the chassis. 

You can do the same thing with the 6800uFs. Just mount em with 3M tape. 







If there is a will, there is a way. This is a nice secure mount


----------



## petewebb (Jan 17, 2022)

HiGHFLYiN9 said:


> I saw you had to creatively mount the snap-in 50uFs (looks very good), didn't realize the resistors had to be moved for the 100uFs. There is real estate back there if you really wanted to fit larger caps, you'd just need to mount them sideways to the board and run leads. There's a lot of dual section caps out there (50uF + 50uF, 100uF + 100uF) so plenty of options. Jensen and Mundorf are both solid choices. The Unicon might be a little too large... those are more for old school builds with the caps protruding from the chassis.
> 
> You can do the same thing with the 6800uFs. Just mount em with 3M tape.
> 
> ...


I attached some screenshots of the 100uFs. There is a resistor and a diode that is pretty close to them, I really didn't need to move them far, as you can see. In fact, they probably would have just fit if I hadn't moved them, but I didn't want anything touching each other.

On the 50uFs, yeah I did have to make some shims out of heat-resistant rubber. The thinner part of the snap-in lead was enough to make them pretty secure when soldered, but I wasn't sure how electrolytic caps deal with vibration so I thought I'd put the dampening shims in there just in case.

You are right though, I think the 6800's would fit if I just tilted the outer ones to the side a bit.

Oh, one thing I forgot to mention, for anyone inserting/removing the 2A3/300Bs for the first time... Those sockets are extremely tight before getting worked in(usually they all are, but this was excessive). I scraped the crap out of the pins on my brand new 2A3s the first time I removed them. Kinda glad it was those and not the WE300s though. I even had Deoxit contact cleaner/lubricant on-hand but was too excited to turn the amp on for the first time and forgot to use it. Don't make that mistake like I did


----------



## HiGHFLYiN9 (Jan 18, 2022)

Very good advice, thanks for that Pete. I'll probably get the 100uF Audio Notes but do something else for the 47uF... or just keep the stock whatever it is. Partsconnexion seems to be out of a lot of stuff so I'm going with HiFiCollective. I need my pink resistors to match!

Since you're done with project maybe you'd like to build the Millett Sangaku? It's a lot less expensive!  You get to build a $2K amp for like $600-700.

...I'm finishing mine up now, just need the fuse. On the topic of creative capacitor mounting... lol. I have Jupiter 0.1uF and Clarity Cap 1.0uF wedged in there. Interestingly they are the identical size.





The DIY addiction never ends...


----------



## petewebb

HiGHFLYiN9 said:


> Very good advice, thanks for that Pete. I'll probably get the 100uF Audio Notes but do something else for the 47uF... or just keep the stock whatever it is. Partsconnexion seems to be out of a lot of stuff so I'm going with HiFiCollective. I need my pink resistors to match!
> 
> Since you're done with project maybe you'd like to build the Millett Sangaku? It's a lot less expensive!  You get to build a $2K amp for like $600-700.
> 
> ...


Oh wow, that looks neat! 

I've got a feeling the Dynaco ST-70 restoration is going to keep me busy for a while though. I just spent all weekend buying up parts and planning the restoration. It's pretty clean as is, it came from the original owner, and even has the original tubes and an unpitted/no-rust chassis.

I also just got a Burson Soloist 3X GT late last year. I need to start using that more as well, also given I spent a bunch of money switching out all the OpAmps for Sparkos.

I'll add the Millett Sangaku to my list for future projects to look at though, Thanks!


----------



## HiGHFLYiN9

Got the kit today! The chassis should play basketball as it's super tall 

I took a look at the electrolytics, and unusually for a kit these are the exact caps I would actually purchase from Mouser for the purpose. 105C and high ripple rating, so they are good enough for wherever my arbitrary line in the sand is. Props to Victor and/or Elekit for packing some good ones. I may bypass with Wima polypropylene on the bottom if I have some in the parts bin. 

The resistors are magnetic (probably steel leads) as well as the 0R jumper resistors (odd that they packed these when people could just use bus wire... maybe it's faster/easier) so I'll probably replace the resistors with cheap and cheerful Takman or Amtrans AMRT and the jumpers with solid silver that can oxidize without detriment. The unit looks like it would accept Cardas posts but the plastic piece that connects them would need to be cut in half. Other than that, it appears no mod is needed. The RCAs are a big mystery and I don't think I'll be able to tell until later in the build. 

Thanks guys for maintaining the fun thread and I'll post updates soon.


----------



## EagleWings

The RCA on it is not a regular one. It has an internal switch and my friend found it shorts to ground or something if no RCA cable is plugged in.


----------



## HiGHFLYiN9

EagleWings said:


> The RCA on it is not a regular one. It has an internal switch and my friend found it shorts to ground or something if no RCA cable is plugged in.


I took a look at them and confirmed there is a mechanism. I've seen that plenty of times on a TRS but not on an RCA before. Will need to stick to stock for those in that case. 

I ordered the resistors from HiFiCollective and should have 'em early next week. It was about $100 to get Takman/Mills replacements for all of them if anyone is budgeting a new build. I know Victor offered them previously but was not stocking at the moment. Also I checked the through-hole dimensions to accept about 22awg or 0.7mm.


----------



## toobuzz

I received a resistor upgrade package for the 8900 yesterday. I’m not quite sure when I’ll get around to installing them, but Victor does seem to have this available. It’s mostly AN Tantalum with a couple AMTRANS and a couple Takman REX50G, a total of 50 resistors. 

I’m also waiting on a pair of Shuguang Treasure 300B-Z to arrive. I look forward to comparing them with the Genelex Gold Lion. 

A friend of mine, @basstrombone80, built an 8600 (with Lundahl) so there will be opportunities for comparisons all around!


----------



## HiGHFLYiN9

The non-magnetic AN tantalums should be very nice in there. If you don't mind my asking what was the package cost? I just got the Takmans yesterday but haven't installed them. If the ANs are a good deal I might be tempted.


----------



## toobuzz (Jan 27, 2022)

So, the ANs appear to be the basic tantalum’s, at least based on the images from Hifi Collective.  I’d hate to put a price in this thread, especially with the current state of supply chain/inflation. I will say that they were in the $250 - $300 range, including overnight shipping. I wasn’t expecting it to be that much, but I like working with and supporting Victor.


----------



## pgkrish

Has anyone tried running the Susvaras out of the speaker taps of the 8600/8900?


----------



## HiGHFLYiN9 (Jan 27, 2022)

Takman resistors and jumpers installed. HiFiCollective had some silver-gold Mundorf wire that wasn't very expensive, so I used that for the jumpers. I noticed their purpose was to allow the board to be printed single-sided for cost reduction, which is perfectly fine. I know first-hand that running an audio business is not as lucrative as it may seem 






Then an end of the day relaxation session.


----------



## toobuzz

Nice update!  I just built a little rca switcher box with that same Mundorf wire. What a great idea to use it for the jumpers. 

I haven’t heard a Susvara, sorry. The HEDDphone directly out of the speaker taps of the 8900 while amazing sounding, has only 1 and a half clicks of usable travel on the TKD pot. I could put it in negative feedback mode but nah, nope. This is kind of why I bought those upgraded resistors.  The headphone implementation seems pretty darn good, if not great on the 8900.


----------



## JamieMcC

pgkrish said:


> Has anyone tried running the Susvaras out of the speaker taps of the 8600/8900?



I don't have Susvaras but do own Hifi Man HE6 which I drive off of the speaker taps (with adapter box) I've owned the HE6 for close to 8  years and tried a number of different amps in that time the TU-8900 drives the he6 superbly with both 2A3 and 300B tubes.


----------



## HiGHFLYiN9

Made a little progress this weekend. Left the V-Cap leads long just in-case I want to change things up with Jupiter Coppers. I found the PCB to be pretty smart with the LED lead-bending tool, the staggered holes to hold the socket strips and the illustrative screen print. This is my first Elekit and I like how they make things accessible. 

Also it was like Where's Waldo trying to figure out where those Zener Diodes went


----------



## HiGHFLYiN9

No real updates as I'm waiting on my powdercoater to have some free time to color the chassis. I did create a vector for an engraved plate. If anyone wants a copy of the file let me know.


----------



## smodtactical

Anyone use tu8800 with hd800 or 650 ?


----------



## Whitigir

I do use TU-8900 with HD800S but I don’t know about the 8800


----------



## dematted

I received this amp around two days ago after getting it built from a really quality guy (the "Headamp Builder" on etsy, if anyone was curious). I basically wanted a TotL amp that could power speakers and headphones and had a good deal of versatility. For the most part, I stuck with Victor's build, but I did sub the vcap cutf's in with some Duelund tinned copper to provide some additional warmth, and I also had my builder tinker a bit with the resistor network that goes to the headphone out after hearing that series resistors tend to degrade the sound. 

A preliminary warning: this amp has only been burnt in for around 35 hours or so, and it supposedly takes quite a bit more time to burn-in. I've been switching between Tung-Sol and Fivre 12BH7a drivers, with Linlai Elite power tubes. So far, I think this amp is pretty remarkable, albeit with a couple important drawbacks. Firstly, in terms of clarity, layering, sheer sense of space, separation, and microdynamic nuance, it is at least a league better than anything that I have heard before (yes, that includes the ECP 3F and TU-8800). It handles music with an ease and effortlessness I don't think I've ever heard before. In short, it provides a clearer window "into" the music than any other amp I've heard, and I've never once heard it sound remotely congested in a busy passage. Though the stage isn't massive, images are extremely well-localized. Bass, though not particularly slamming, has a supremely nuanced sense of pitch, texture, and control. And the sense of decay, delineation and air around treble notes is at times awe-inspiring: the cymbals in "dreams" seem to run on forever, and one can actually hear with more tangibility the precise changes in volume of these instruments as the strike of the cymbal decays slowly into nothingness. All this is, to say the least, fairly impressive.

That being said, I do have some quibbles with the way that it represents instrument textures in the mid-range. It has a sort of high-end "sheen" to it which tends to lead to a homogenization of mid-range timbres. For what it's worth, this is something I've heard on every amp with Lundahl transformers (including the 3F and 8800), though to a perhaps lesser extent than what is present in the 8900. In short, there's a kind of almost artificial top-end sparkle that crowds out the crunch and presence of mid-range elements like voices and strings while also tending to make their timbres all sound alike. It also is just a tad harsh-sounding, akin to the way that a Focal sounds, albeit without the "metallic" timbre or "edge" to the transients. In fact, the transient edges are, if anything, not adequately well-represented: the amp lacks a certain sense of grunt and bite that even the much cheaper ZMF Pendant OG had. Since this amp also tends to lack any sort of notable warmth or wetness in the mid-range, this can occasionally lead to a sound that is simultaneously sterile and unengaging. For the most part, I don't find myself tapping my foot with this amp despite it having what I think are the best microdynamics I've ever heard - there just isn't enough sense of "realism" and palpability to the instruments or attack in the transients, two things which I think are essential to musical engagement.

For what it's worth, many of these problems have been getting less noticeable as the amp has burnt in, and I also think that they are at least partially due to the pairing with the Soekris 2541, especially since this amp is supposedly quite sensitive to sources. In fact, when I used my loaner r2r Cayin dongle, many of these issues, particularly the timbral ones, entirely disappeared, though the amp did take a hit technically. What I surmise from this is that to a good extent, this amp tends to take on the timbre of the sources that it's used with. In this way, this amp reminds me a good deal of the Focal Utopia - it's extremely revealing and a tad on the thin side, so pairing with the correct components is going to be absolutely essential to getting the most out of it, since its sheer transparency will tend to make it very sensitive to the gear that it is paired with.

I am going to burn-in this amp a good deal more, potentially swap caps, and give it a go with an Abbas 2.3se, since I really do think it would benefit from an aggressive, full-bodied dac (the soekris 2541, which is simultaneously thin, relaxed, and lacking in plankton, seems like exactly the -wrong- kind of pairing for this amp). I will let you all know what I think when I do so, but for now, this amp is not quite the slam dunk which I thought it would be.


----------



## HiGHFLYiN9

dematted said:


> That being said, I do have some quibbles with the way that it represents instrument textures in the mid-range. It has a sort of high-end "sheen" to it which tends to lead to a homogenization of mid-range timbres. For what it's worth, this is something I've heard on every amp with Lundahl transformers (including the 3F and 8800), though to a perhaps lesser extent than what is present in the 8900. In short, there's a kind of almost artificial top-end sparkle that crowds out the crunch and presence of mid-range elements like voices and strings while also tending to make their timbres all sound alike. It also is just a tad harsh-sounding, akin to the way that a Focal sounds, albeit without the "metallic" timbre or "edge" to the transients.


This is an interesting observation, and diving into the details I suppose it's not surprising.

From what I've discovered over the years is that with wire, the dielectric makes much of the audible difference. If you look at Nordost cables for example, they are thin and wide which allows the most amount of surface area for dielectric to affect. People tend to say that Nordost cables emphasize the top-end. Cardas cables use individual isolated enameled strands in the typical round wire configuration and are generally thought of as "warm". 

The understanding that with tube amps with OPTs, much of what you are listening to is the OPTs, thus the need for quality. So what we can infer from different sounding cables is that the dielectric will make a notable difference in these OPTs. Now where normal transformers are just wrapped bobbin-style with magnet wire where the only real insulation is the enamel coating, Lundahl uses insulation between each layer that's wrapped around the core. Given that there is a large amount of wire surrounded by dielectric the output has to go through to reach the binding posts, the dielectric is likely causing the effect you are describing. For people who subscribe to burn-in, the belief is that the dielectric forms after so many hours. The empirical and far-from-scientific rule of thumb that PVC, PE, XLPE, etc. are usually around 100 hours, and PTFE around 200. Even after a period of burn-in, I don't think the Lundahls will ever sound like a typical bobbin transformer because of the way the dielectric is employed. The way Lundahls are made is more expensive, more thoughtful, and they likely measure better than a typical transformer, but at the end of the day it's listener preferences that matter most. You may find that you prefer the standard OPTs over the Lundahls if things don't settle in the way you'd like. 

Given how much the OPTs affect the sound, you can understand the motivation for the Berning designs that mostly eliminate them. Still I enjoy both options


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## JamieMcC

Welcome to the club

Your not alone several of us here have had similar experiences with how the amp sounds when new. I was seriously underwhelmed myself during initial listening.  

Stick with it and rack up the hours once past 100hrs I thought there was a significant improvement. I also noticed a similar sheen which was very distracting once heard but had put it down to the V-Cap cutf which requires a notoriously long burn in. However I am open to this effect possibly being the AM transformers as well

Fwiw  thankfully whatever the cause after around 500 hours it had disappeared completely.


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## Whitigir (Feb 16, 2022)

dematted said:


> I received this amp around two days ago after getting it built from a really quality guy (the "Headamp Builder" on etsy, if anyone was curious). I basically wanted a TotL amp that could power speakers and headphones and had a good deal of versatility. For the most part, I stuck with Victor's build, but I did sub the vcap cutf's in with some Duelund tinned copper to provide some additional warmth, and I also had my builder tinker a bit with the resistor network that goes to the headphone out after hearing that series resistors tend to degrade the sound.
> 
> A preliminary warning: this amp has only been burnt in for around 35 hours or so, and it supposedly takes quite a bit more time to burn-in. I've been switching between Tung-Sol and Fivre 12BH7a drivers, with Linlai Elite power tubes. So far, I think this amp is pretty remarkable, albeit with a couple important drawbacks. Firstly, in terms of clarity, layering, sheer sense of space, separation, and microdynamic nuance, it is at least a league better than anything that I have heard before (yes, that includes the ECP 3F and TU-8800). It handles music with an ease and effortlessness I don't think I've ever heard before. In short, it provides a clearer window "into" the music than any other amp I've heard, and I've never once heard it sound remotely congested in a busy passage. Though the stage isn't massive, images are extremely well-localized. Bass, though not particularly slamming, has a supremely nuanced sense of pitch, texture, and control. And the sense of decay, delineation and air around treble notes is at times awe-inspiring: the cymbals in "dreams" seem to run on forever, and one can actually hear with more tangibility the precise changes in volume of these instruments as the strike of the cymbal decays slowly into nothingness. All this is, to say the least, fairly impressive.
> 
> ...


Welcome to the club, and it sounds like you are in Negative feedback mode, try removing it ?


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## JamieMcC

Interestingly listening session this evening after starting off with hd800 and later deciding to switch to the he6. I tend to listen with the hd800 from the front panel the most as have some speakers hooked up on the rear, due to placing it's a bit of a faff to swap from the speakers to adaptor box to run the He6.

This was actually the first time running the HE6 with 300B and no feedback. What bowled me over was the amount of texture and saturated tone present with the he6 its  effortless liquidity along with that visceral punch its renowned for. Very much an immersive and music first experience a lot of the technicals still present but not dissected and presented as spacious as with the hd800. 

Once in a while I have the silly notion to move on the he6 as it often sits gathering dust whilst the hd800 hogs the limelight but it's sessions like this that remind me what a fantastic headphone it is and just how enjoyable listening in what feels like technicolour compared to the hd800 can be.

If only there was a headphone combing the best of both of these old flagships of yesteryear.....end game for sure.


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## Maven86

Just in case anyone wanted to know the output Z values for the different headphone settings.  Had the missus send Elekit an e-mail and they responded promptly:

LZ-L:  3.1ohm
LZ-M:  7.2ohm
LZ-H:  15ohm
HZ-M:  26ohm
HZ-H:  60ohm

You can also calculate the values yourself using the circuit schematic in the back of the manual.  Just sum up the resistor values in the corresponding circuit path and plug them into the calculator below (for resistors in parallel, the value will be inverse e.g 120ohm --> 1/120ohm).

http://www.sengpielaudio.com/calculator-InputOutputImpedance.htm

There's also a formula there for those who are all about that pen and paper method.  Compliments to @HiGHFLYiN9 for the link and resources.


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## Whitigir

Maven86 said:


> Just in case anyone wanted to know the output Z values for the different headphone settings.  Had the missus send Elekit an e-mail and they responded promptly:
> 
> LZ-L:  3.1ohm
> LZ-M:  7.2ohm
> ...


Thank you ! Glad you have got that out of the way


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## Whitigir

HiGHFLYiN9 said:


> No real updates as I'm waiting on my powdercoater to have some free time to color the chassis. I did create a vector for an engraved plate. If anyone wants a copy of the file let me know.


Is that metal engraved plate ?

Could you customize something like “Lundahl Inside” ? Or something to indicate that the amp has Lundahl upgraded ?


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## HiGHFLYiN9

Whitigir said:


> Is that metal engraved plate ?
> 
> Could you customize something like “Lundahl Inside” ? Or something to indicate that the amp has Lundahl upgraded ?


Yes, I do the art and have a trophy shop make them for me. I'm sure I could. I'm not sure I'd do it for mine but if you want me to make a vector for you and give you the store contact just let me know.


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## smodtactical

Just want to share a data point. I just built a BH Crack OTL amp.. no speed ball. And with my 800S, BS650 and ZMF atticus it sounds absolutely incredible. I really like the elekit tu8600 off the taps with a speaker tap cable but the Crack just sounds bigger, more 3d with better layering, more full romantic mid range. I was shocked an amp that costs $400 sounded so much better than a $2500+ tubes amp. But I guess elekit is a speaker amp first. This is btw a pretty upgraded elekit and Ive rolled elrog 300b, WE300b clones and all mullard input tubes.


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## jamato8

smodtactical said:


> Just want to share a data point. I just built a BH Crack OTL amp.. no speed ball. And with my 800S, BS650 and ZMF atticus it sounds absolutely incredible. I really like the elekit tu8600 off the taps with a speaker tap cable but the Crack just sounds bigger, more 3d with better layering, more full romantic mid range. I was shocked an amp that costs $400 sounded so much better than a $2500+ tubes amp. But I guess elekit is a speaker amp first. This is btw a pretty upgraded elekit and Ive rolled elrog 300b, WE300b clones and all mullard input tubes.


What OPTs?


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## smodtactical

jamato8 said:


> What OPTs?


Lundahl, vcap odams, tkd pot, takman


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## Maven86

smodtactical said:


> Just want to share a data point. I just built a BH Crack OTL amp.. no speed ball. And with my 800S, BS650 and ZMF atticus it sounds absolutely incredible. I really like the elekit tu8600 off the taps with a speaker tap cable but the Crack just sounds bigger, more 3d with better layering, more full romantic mid range. I was shocked an amp that costs $400 sounded so much better than a $2500+ tubes amp. But I guess elekit is a speaker amp first. This is btw a pretty upgraded elekit and Ive rolled elrog 300b, WE300b clones and all mullard input tubes.


Have you tried those phones out of the headphone out via position 4 on the Elekit?


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## toobuzz

I mean, correct me if I’m wrong, running off the speaker taps would be a much lower output impedance than running out of the headphone section of the 8600 (or 8900, but especially the 8600 as it’s headphone section is much higher output impedance than the 8900). In that case, it is obvious to me why those particular high impedance headphones would sound awesome out of a Crack.


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## Maven86 (Mar 14, 2022)

toobuzz said:


> I mean, correct me if I’m wrong, running off the speaker taps would be a much lower output impedance than running out of the headphone section of the 8600 (or 8900, but especially the 8600 as it’s headphone section is much higher output impedance than the 8900). In that case, it is obvious to me why those particular high impedance headphones would sound awesome out of a Crack.


That's pretty much it.  If you were to remove the two highest output Z settings on my 8900, I'd choose the crack everytime with any high Z Senn or my ADX5000.  IME with some headphones, usually those with higher Z, impedance matching is crucial.


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## HiGHFLYiN9

smodtactical said:


> Just want to share a data point. I just built a BH Crack OTL amp.. no speed ball. And with my 800S, BS650 and ZMF atticus it sounds absolutely incredible. I really like the elekit tu8600 off the taps with a speaker tap cable but the Crack just sounds bigger, more 3d with better layering, more full romantic mid range. I was shocked an amp that costs $400 sounded so much better than a $2500+ tubes amp. But I guess elekit is a speaker amp first. This is btw a pretty upgraded elekit and Ive rolled elrog 300b, WE300b clones and all mullard input tubes.


Hey you like what you like   It sounds like you are into the vintage warm tube sound. If you get into speakers check out the Dynaco ST70 or Cary Audio Six Packs, both very warm and full sounding. You'd also probably like the Little Dot mkII, I think that is the warmest sounding amp I've heard. 

I've built a couple of Cracks ages ago, one standard and one with a 6SN7, and while they are fun they never really buttered my biscuits all that much. I moved on to a WooAudio3 which I found to be a little more resolving with the same warmth. It was a more complicated circuit. The Crack is about as simple as you can get which can be helpful for some objectives. 

Best amp I've heard is still the LTA MZ3, but that's with lower impedance headphones. It's much more neutral than a Crack. I still haven't finished my 8900 though so the comparison remains to be seen. I gotta get to the powdercoater soon.


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## JamieMcC (Mar 14, 2022)

smodtactical said:


> Just want to share a data point. I just built a BH Crack OTL amp.. no speed ball. And with my 800S, BS650 and ZMF atticus it sounds absolutely incredible. I really like the elekit tu8600 off the taps with a speaker tap cable but the Crack just sounds bigger, more 3d with better layering, more full romantic mid range. I was shocked an amp that costs $400 sounded so much better than a $2500+ tubes amp. But I guess elekit is a speaker amp first. This is btw a pretty upgraded elekit and Ive rolled elrog 300b, WE300b clones and all mullard input tubes.



This is interesting.

I've built around a dozen Cracks some stock some hot rodded including a side to side listening of stock Vs fully tricked out with grail tubes. I could never ever imagine building a stock Crack for personal use again.

Though I do rember in his review Steve Guttenberg mentioned the 8600 TRS out was not the best.

Be interested to know what the rest of your chain is as the Crack is known not to be very transparent with a intimate soundstage.

So something seems a miss to me though I will freely admit I've never heard the TU8600 but the thought of the Crack besting it in anything but in saturated intimate tonality and rawness I find a bit shocking. Surely the TU8600 headphone performance can not be so poor as to be bested by a stock vanilla Crack.

Fwiw by far my favourite Crack was a non speedball one hot rodded with high speed diodes, Triad choke and the last electrolytic power supply cap replaced with a large film (motor run cap) and then three 30uf ex Russian military surplus Mbgo paper in oil tub capacitors aside for output caps with Russian teflon bypass capacitors and a glassware 36 step course and fine attenuator.

Superb liquid tonality and very much a beguiling listen if ever I was build one again it would be along those lines.

Also have the Bottlehead Sex and Mainline at home but the hd800 paired with the TU8900 I feel plays in a different league.


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## Maven86 (Mar 14, 2022)

JamieMcC said:


> This is interesting.
> 
> I've built around a dozen Cracks some stock some hot rodded including a side to side listening of stock Vs fully tricked out with grail tubes. I could never ever imagine building a stock Crack for personal use again.
> 
> ...



Definitely agree about the 8900 being in a different league and to a lesser extent the 8600 was as well.  Maybe you both just have different preferences as to what kind of sound sig you're looking for.  That being being said, I think I get why he likes the crack.  From my experience, it's not the most resolving amp but when paired with certain High Z phones, like the Senn 6X0s, you get a very engaging sound with great PRaT and holographic imaging.  The caveat is that this is also true out of the high Z outputs for almost any other decent amp I've tried including the A&S Kenzie, Zana Deux, and to a greater extent the 8900...along with the benefit of more resolution and other perks as you move up the chain.



HiGHFLYiN9 said:


> Hey you like what you like   It sounds like you are into the vintage warm tube sound. If you get into speakers check out the Dynaco ST70 or Cary Audio Six Packs, both very warm and full sounding. You'd also probably like the Little Dot mkII, I think that is the warmest sounding amp I've heard.
> 
> I've built a couple of Cracks ages ago, one standard and one with a 6SN7, and while they are fun they never really buttered my biscuits all that much. I moved on to a WooAudio3 which I found to be a little more resolving with the same warmth. It was a more complicated circuit. The Crack is about as simple as you can get which can be helpful for some objectives.
> 
> Best amp I've heard is still the LTA MZ3, but that's with lower impedance headphones. It's much more neutral than a Crack. I still haven't finished my 8900 though so the comparison remains to be seen. I gotta get to the powdercoater soon.


I mentioned not too long ago that I finally got to try the MZ3 over at LTA.  With the planars like the LCD-X they had, it sounded very good.  Neutral and transparent with excellent bass...  I then plugged in my ADX5000 and the first thing I said was "what's the output impedance on these...?".  Apparently for an OTL, it was only 2 ohms.  The second highest output Z on the 8900 is allegedly 27ohms and out this setting I thought the ADX5000 was....meh.  Out of the MZ3, it was just dead.


----------



## jamato8

Maven86 said:


> I thought the ADX5000 was....meh.  Out of the MZ3, it was just dead.


I am not sure what that means. :^)


----------



## Maven86

jamato8 said:


> I am not sure what that means. :^)


From my experience, my preference for certain high Z phones like the ADX5000 seems to be heavily dependant on the output impedance of the amplifier.  For example on the TU-8900, I think they sound amazing from the 60 ohm tap but just ok from the the 27 ohm one.  As I go lower, I tend to like them less and less.  At 2 ohms, they sound flat, boring, and lifeless.


----------



## EagleWings

Sometime in the future, I have plans of converting my 8900 into a pure HP amp by swapping in some custom OPTs with 8Z and 50Z secondaries.


----------



## HiGHFLYiN9

Haha I'll admit I pretty much only listen to low impedance cans these days. My HD650 and DT990 600R probably need a good dusting.


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## Maven86

HiGHFLYiN9 said:


> Haha I'll admit I pretty much only listen to low impedance cans these days. My HD650 and DT990 600R probably need a good dusting.


Nothin wrong with some low Z luv.  Honestly, they're a lot easier to pair with most of the current gear we have around.


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## JamieMcC (Mar 14, 2022)

Might be of interest but when I was ABing the stock and modded Crack with premium tubes I was using both hd650 and Beyer T1.  The HD650 sounded good on both amps but the T1 on the stock Crack was cold and lifeless, dead for a better word  not what you would think at all being a hi Z phone (600 ohm) and OTL

However the Modded Crack gave the T1 a kiss of life great mids non sibilant, fast bass it was like listening to a completely different headphone it now had soul. Hard to believe what a difference just swapping a few like for like components can make.

Talking about measurements determining audio performance not sure where I saw it don't think it was audio related but medical science and how we can now see and measure virtually inside out the human body Xray, CT Cat scan, Mri scanner, genome profiling etc  but non of todays science can tell you the character of a person, kind, generous, loyal, evil, honest, dishonest etc perhaps one of the most important things that makes us human. Just thought it interesting.


----------



## HiGHFLYiN9

IIRC the original T1s were 250 ohms whereas the current ones are 32 ohms, correct? Litz copper (e.g. Cardas) can help with that spiky upper midrange to some extent. 

Whenever I recable a T1 or T5p and test them before shipping they always surprise me and remind me of how good dynamic drivers can be. Great headphones. They've definitely fallen off the popularity index compared to HiFiMan and Focal but I think they are still very relevant. 

Also of note, sometimes I measure headphones and they aren't the impedance they state on the website, actually quite different sometimes, so it probably can't hurt to double check before you order a custom OPT  I want to say my LCD-4 is like 40 ohms when the site says 200. Beyers are usually pretty close IIRC.


----------



## Maven86

HiGHFLYiN9 said:


> IIRC the original T1s were 250 ohms whereas the current ones are 32 ohms, correct? Litz copper (e.g. Cardas) can help with that spiky upper midrange to some extent.
> 
> Whenever I recable a T1 or T5p and test them before shipping they always surprise me and remind me of how good dynamic drivers can be. Great headphones. They've definitely fallen off the popularity index compared to HiFiMan and Focal but I think they are still very relevant.
> 
> Also of note, sometimes I measure headphones and they aren't the impedance they state on the website, actually quite different sometimes, so it probably can't hurt to double check before you order a custom OPT  I want to say my LCD-4 is like 40 ohms when the site says 200. Beyers are usually pretty close IIRC.


Not sure what they actually measure but I think the official specs say 600 ohm.  Funny you mentioned the T1.  One of the first "hifi" headphones I ever owned were a pair of DT880s.  At the time the T1 was my dream headphone if I were to ever go off the deep and splurge... 10 years later and deeper down the rabbit hole than I ever expected, they still come up at random times as an itch that needs to be scratched despite being drowned out by all the new stuff that seems to come out every other week.  



JamieMcC said:


> Might be of interest but when I was ABing the stock and modded Crack with premium tubes I was using both hd650 and Beyer T1.  The HD650 sounded good on both amps but the T1 on the stock Crack was cold and lifeless, dead for a better word  not what you would think at all being a hi Z phone (600 ohm) and OTL
> 
> However the Modded Crack gave the T1 a kiss of life great mids non sibilant, fast bass it was like listening to a completely different headphone it now had soul. Hard to believe what a difference just swapping a few like for like components can make.
> 
> Talking about measurements determining audio performance not sure where I saw it don't think it was audio related but medical science and how we can now see and measure virtually inside out the human body Xray, CT Cat scan, Mri scanner, genome profiling etc  but non of todays science can tell you the character of a person, kind, generous, loyal, evil, honest, dishonest etc perhaps one of the most important things that makes us human. Just thought it interesting.


Interesting experience with the Beyers.  I probably would have been a little surprised but it goes to show that no one variable, output Z included, is a guarantee that something will be a good match.  

Really liked that medical analogy.  Measurements are essential and definitely have their place but over the years, when it comes down to what I actually hear and enjoy in terms of sound, I've become much more of a subjectivist.


----------



## toobuzz

I really do like the 2A3 in the 8900 for headphones and previously I said that I preferred it. That was a bit premature as I had only heard the non-gold grid EH 300B at the time. I popped in some Gold Lion and Shuguang Treasure 300Bs over the weekend I spent a good amount of time testing each jumper setting with my HD800.  I only have about 3-4 clicks on the TKD pot but the 60 ohm setting is definitely my favorite. 

I use a track with a real sub-bass crescendo (2:52 on Heatwaves by Glass Animals).  I cannot hear anything on the 2 lowest jumper settings, well I suppose I hear a weak flutter. But it sounds amazing on the highest Z setting.  

At the moment the Crackatwoa and 8900 are my favorite amps for casual listening on the HD800 (always the Mainline for classical music, always).  

I use a 300B preamp in my stereo so I am loving that 300B sound on the 8900 in contrast to the OTL Crackatwoa.  My C2A is kinda maxed out with RCA red base 6SN7 and WE 421A and some huge Munford caps. 

I think the OG HD800 is so underrated. It can hit like an Arya, I’m telling you it can!  On both of these amps, the bass on the HD800 is so good and the rest of the “issues” are basically non-existent between the high Z of the C2A and the medium Z + Lundahl of the 8900.


----------



## smodtactical

Maven86 said:


> Have you tried those phones out of the headphone out via position 4 on the Elekit?



Nah mostly just use the speaker taps with a tap cable.


----------



## smodtactical

Listening to BS650 + Crack OTL and its hypnotizing. On Crack OTL I feel like i can hear all these details i didnt hear before. Subtle nuances. It is weird I don't understand why.  Is it because the song is relaxed and allowing me to notice things that are more subtle since foreground detail is not jumping out into my face ?


I love this amp so much I can't describe it even. And its surrounded by amps that cost thousands more but I think i prefer Crack over everything i have.


----------



## Maven86 (Mar 15, 2022)

smodtactical said:


> Nah mostly just use the speaker taps with a tap cable.


Give it a shot, you might be surprised. 

At the end of the day you like what you like, nothing wrong with that.  Glad the crack combo is working well for you.


----------



## Whitigir (Mar 15, 2022)

toobuzz said:


> I really do like the 2A3 in the 8900 for headphones and previously I said that I preferred it. That was a bit premature as I had only heard the non-gold grid EH 300B at the time. I popped in some Gold Lion and Shuguang Treasure 300Bs over the weekend I spent a good amount of time testing each jumper setting with my HD800.  I only have about 3-4 clicks on the TKD pot but the 60 ohm setting is definitely my favorite.
> 
> I use a track with a real sub-bass crescendo (2:52 on Heatwaves by Glass Animals).  I cannot hear anything on the 2 lowest jumper settings, well I suppose I hear a weak flutter. But it sounds amazing on the highest Z setting.
> 
> ...


Yes, 8900 is amazing with HD800S, High Z/ Low gain and 2A3



Maven86 said:


> Give it a shot, you might be surprised.
> 
> At the end of the day you like what you like, nothing wrong with that.  Glad the crack combo is working well for you.



I am glad that I didn’t go with 8600.  Mainly I loved the idea of having the auto bias and fool proof protections on 8900.  I can simply plug in, power up and forget it.  I can’t say for 8600 but to me the 8900 and 2A3 Non NFB is amazing with 800S


----------



## smodtactical

Has anyone compared the tu8600 off the speaker taps to other high end tube headphone amps like dna stratus/stellaris, ec studio, apex Teton etc ?

I know a couple people that said that 8600 is in the same league as stellaris.


----------



## Whitigir (Apr 10, 2022)

Edited *


----------



## jamato8

Whitigir said:


> I have some free time and will be able to tackle these projects additionally.  If anyone who would like to have one built with all the upgrades and even further options in the USA, you can contact me through PM or email


That is good to know.


----------



## JamieMcC

. Wrong BB apologies


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## JamieMcC

Eight months in now on my TU-8900 and I honestly think the amp is sounding better than ever.

Every couple of weeks or so it's really very enjoyable to swap tube types and enjoy a different flavour.

Cheers all and have a good weekend 👍


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## Whitigir

JamieMcC said:


> Eight months in now on my TU-8900 and I honestly think the amp is sounding better than ever.
> 
> Every couple of weeks or so it's really very enjoyable to swap tube types and enjoy a different flavour.
> 
> Cheers all and have a good weekend 👍


This amp is really amazing, even though the THD and specs are not impressive on paper, the performances is something that you gotta listen to it to believe.


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## vkung (May 13, 2022)

you need to listen the amp with two silver caps... if you go to HingEnd Show in Germany, you can hear the huge improvement..


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## Whitigir

vkung said:


> you need to listen the amp with two silver caps... if you go to HingEnd Show in Germany, you hear the huge improvement..


What silver caps do you recommend ?


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## vkung

AN Silver..


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## HiGHFLYiN9

What's the cost of those? 






...or should I even ask?


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## vkung

Email pls


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## Maven86

Whitigir said:


> What silver caps do you recommend ?


There's also Duelund.  I can vouch for those.


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## jamato8

HiGHFLYiN9 said:


> What's the cost of those?
> 
> 
> 
> ...or should I even ask?


You have answered yourself. :^)


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## vkung

Duelund is not the right size for TU-8900


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## petewebb

vkung said:


> Duelund is not the right size for TU-8900



The Duelunds do fit with ample space below the pcb though.


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## vkung

petewebb said:


> The Duelunds do fit with ample space below the pcb though.


I try several silver caps . AN is easier to install. No need to do a lot of modifications


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## JamieMcC

Fwiw for those without deep pockets the Duelund JDM silver foil bypass caps are always a option I used them to bypass the V-Cap Cutf in my 8900 and have been very happy with the results.
👍


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## Whitigir

JamieMcC said:


> Fwiw for those without deep pockets the Duelund JDM silver foil bypass caps are always a option I used them to bypass the V-Cap Cutf in my 8900 and have been very happy with the results.
> 👍


Where do you buy the, from ? Just curious, Ty


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## JamieMcC

Whitigir said:


> Where do you buy the, from ? Just curious, Ty



I brought mine from Hifi collective 
Think they were about £30 each.


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## Lickumms

Anyone have a comparison of the Elekit TU-8900/8600 to the Bottlehead Kaiju?


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## JamieMcC

Lickumms said:


> Anyone have a comparison of the Elekit TU-8900/8600 to the Bottlehead Kaiju?



There are some views of owners who have had both posted I can't remember if they were on this thread or another on headfi see if the the Search function turns up sometime.


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## Lickumms

JamieMcC said:


> There are some views of owners who have had both posted I can't remember if they were on this thread or another on headfi see if the the Search function turns up sometime.


I couldn't really find any comparisons. Just one person said they like the 8600.


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## JamieMcC (Jul 30, 2022)

Lickumms said:


> I couldn't really find any comparisons. Just one person said they like the 8600.



Maybe it was on another BB there are definitely some comments from owners of both Kaiju and 8600 out there.

I was looking for the same answers as well. 
After building many of the different Bottlehead kits myself the Kaiju seemed the natural choice long before I had heard of Elekit. 

Fwiw as a long time lurker on the Bottlehead forum the topic of the Kaiju for headphone use comes up quite regularly BH recommend the DC power upgrade supply option if using headphones.

One of Bottlehead designers also has commented

"If you aren't powering K-1000's, HE-6's, or a similar pair of headphones, I would take a more serious look at the Mainline."

As a Bottlehead Mainline builder/user for the last 7 years fwiw it's definitely my impression the 8900 brought a noticeable improvement over the Mainline imho

My cravat here would is that it required a Chord Dave for me to reach that conclusion. With my other DACs best of which currently is a Oppo 205 it's hard to notice the differences between them it's only when moving up to the Dave that the limitations of the Mainlines abilities become apparent and the Elekit 8900 pulls ahead particularly in transparency and 3D spaciality.


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## Whitigir (Jul 30, 2022)

People don’t know much about Elekit, because it is DIY and also not heavily advertised

However, I can tell when there are great performances as I have been in this hobby long enough.

The Elekit when done right can be A very very expensive performers.  In one of the review from the kit, there was a quote that this is comparable to a $20,000 amp.  But I honestly think that it can even be comparable to a much more expensive than that

Listening to this combo this morning and HD800S, not only the sound stage is so vivid and huge, but the details, timbres, extensions, and acoustic cues are superb! Goose bumps providing performances


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## Galapac

Whitigir said:


> People don’t know much about Elekit, because it is DIY and also not heavily advertised
> 
> However, I can tell when there are great performances as I have been in this hobby long enough.
> 
> ...


I have the TU-8600S version and couldn’t agree more in terms of quality build and value for your money. The Elekits with cap/resistor upgrades exceed my expectations and it is more elegant build IMO. Well thought out using PCB instead of point to point wiring and made to high standards.

If you want to build one of these VKMusic in Canada should be your only source if you live in North America. You will not get your kit cheaper (Victor is the supplier for North America and sells to other dealers) and his prices are fair for upgrades/tubes, etc. His customer service is top notch and ships extremely fast, as in next day. Great experience all around.


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## Lickumms (Aug 4, 2022)

How do the 2a3 sound compared to the 300B? Or is the 8900 better at 1 tube type over the other?


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## EagleWings

*Linlai WE300B vs Linlai WE2A3:*

Given that the TU8900 errs on the dry side of things, I went with the WE series from Linali over the Elite series for both 300B and 2A3. So take this comparison for how the 300B and the 2A3 compare on the 8900 only. 

The 300B comes across as being more macro tilted relative to the more linear and nuanced sounding 2A3. The 300B hits harder with more weight in the bass, is warmer in the mids and smoother in the overall treble. While the 2A3 is not as warm in the midrange, it seems more filled out in the notes, so it sounds denser and bolder. While it is the brighter and the less forgiving between the two, it is also the more transparent and resolving valve. It retrieves more micro information and shows differences between albums and sources more easily. Overall, the 2A3 pulls off the spooky realism better than the 300B.

On the presentation and stage side of things, 300B throws a larger stage and has a grander overall presentation. But the depth and layering capabilities of both the valves are in the same ball park. The 2A3 however images more precisely in the stage. For OSTs, where I don’t mind giving up a bit of timbral realism for a grander presentation, 300B + HD800 combo is quite a treat. But then with the 580 and 650, which have become my daily drivers, I seem to be reaching for the 2A3 more. 

On the speaker front, I don’t have any 2A3 friendly speakers, so the 300B has been the winner there, just because of its greater output power and greater macro performance. But I can’t wait to get hold of some 2A3 friendly speakers to see if it can dethrone the 300B.


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## Maven86

EagleWings said:


> *Linlai WE300B vs Linlai WE2A3:*
> 
> Given that the TU8900 errs on the dry side of things, I went with the WE series from Linali over the Elite series for both 300B and 2A3. So take this comparison for how the 300B and the 2A3 compare on the 8900 only.
> 
> ...


You pretty much hit the nail on the head with this.  Just out of curiosity, what speakers are you currently running?  I felt that full range speakers (no crossover) paired really well with the 2A3s and other lower output DHTs (45, 71A ect).

I tried a few other high efficiency setups despite some having efficiency ratings above 97db, I always felt like they benefited from the extra juice of the 300Bs.  My old pair of Coherents with Radian drivers were the same way.  They sounded pretty good with the 2A3s but relatively "flat" dynamic wise without the nuance and microdetail I was hearing from even modest headphones (HD580, 650 ect.). With Omegas or Lowthers, I never had any desire to put 300Bs back in.


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## EagleWings

Maven86 said:


> You pretty much hit the nail on the head with this.  Just out of curiosity, what speakers are you currently running?  I felt that full range speakers (no crossover) paired really well with the 2A3s and other lower output DHTs (45, 71A ect).
> 
> I tried a few other high efficiency setups despite some having efficiency ratings above 97db, I always felt like they benefited from the extra juice of the 300Bs.  My old pair of Coherents with Radian drivers were the same way.  They sounded pretty good with the 2A3s but relatively "flat" dynamic wise without the nuance and microdetail I was hearing from even modest headphones (HD580, 650 ect.). With Omegas or Lowthers, I never had any desire to put 300Bs back in.



Yep, can totally relate to that. I am currently running a pair of Lii F15 (no crossovers). While its not bad in the micro dept, its forte are dynamics, macro swings and scale. The 2A3 makes the drivers sound like a regular bookshelf. It works better off the 300B, but gets even better with 25W or so. So the plan is to get a push pull pentode amp for the F15 and a set of speakers that would work better with 2A3s. But the plan is on hold right now for a couple of reasons. I would have liked to go for a pair of Omega, if those were available here. I will look into the Lowthers. I’ve been avoiding those, as I’ve heard those can be bright and shouty.


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## Maven86

Thought this was pretty baller.  Someone had custom OPTs made for the 8900 with Finemet cores and OCC silver windings.  Probably sounds amazing but I'd hate to see the price and weight on those anvils.


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## jamato8

Maven86 said:


> Thought this was pretty baller.  Someone had custom OPTs made for the 8900 with Finemet cores and OCC silver windings.  Probably sounds amazing but I'd hate to see the price and weight on those anvils.



There was extensive studies and measurements done about all silver vs copper to the secondary being silver. The copper to the secondary being silver is just as good! And obviously less expensive.


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## Maven86

jamato8 said:


> There was extensive studies and measurements done about all silver vs copper to the secondary being silver. The copper to the secondary being silver is just as good! And obviously less expensive.


I think it might have been silver in the secondaries that supposedly made a bigger difference.  At least from the literature I’ve read.

Either way, quite a few have had different subjective impressions despite measurements saying otherwise.


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## Beefy

Maven86 said:


> Thought this was pretty baller.  Someone had custom OPTs made for the 8900 with Finemet cores and OCC silver windings.  Probably sounds amazing but I'd hate to see the price and weight on those anvils.




Baller, but surely nutty. So much effort into transformer loading, when I'd bet switching to a parafeed design would bring better improvements.


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## jamato8

Maven86 said:


> I think it might have been silver in the secondaries that supposedly made a bigger difference.  At least from the literature I’ve read.
> 
> Either way, quite a few have had different subjective impressions despite measurements saying otherwise.


I would think all silver would be just a bit better.


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## Maven86

Beefy said:


> Baller, but surely nutty. So much effort into transformer loading, when I'd bet switching to a parafeed design would bring better improvements.


I think nutty is just intrinsic to the hobby.  Would have probably stopped with a nice OTL and high Z Senn if I had all my marbles.


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## Beefy

Maven86 said:


> I think nutty is just intrinsic to the hobby.  Would have probably stopped with a nice OTL and high Z Senn if I had all my marbles.



Oh, absolutely. But I'd like to think you can direct the nuttiness. Making a stupid expensive air-gapped transformer to be a tube load just seems silly, when you could have a much better parafeed transformer for less money.

On a related topic, I recently put forward my best argument to Bottlehead to make a DHT amp specifically for headphones. Didn't seem like there was much interest, which I think is a big shame. There's a lot to love about the Elekit, but I still have an inescapable feeling that forgoing the speaker outs, and designing specifically for headphones, would yield a much better product for Head-Fi'ers.


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## JamieMcC (Aug 26, 2022)

Beefy said:


> On a related topic, I recently put forward my best argument to Bottlehead to make a DHT amp specifically for headphones. Didn't seem like there was much interest,



Fyi Bottlehead used to support conversion of their battery powered dht Quickie preamp (kit no longer available but very simple circuit) for headphone use. There used to be a how to thread if I remember correctly it was around the $150-$200 to build the kit and then convert it I know there were also a few who liked it well enough to build hot rodded versions with more premium parts and linear power supplies using Rod Colman filament Regulators.


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## Maven86

Beefy said:


> Oh, absolutely. But I'd like to think you can direct the nuttiness. Making a stupid expensive air-gapped transformer to be a tube load just seems silly, when you could have a much better parafeed transformer for less money.
> 
> On a related topic, I recently put forward my best argument to Bottlehead to make a DHT amp specifically for headphones. Didn't seem like there was much interest, which I think is a big shame. There's a lot to love about the Elekit, but I still have an inescapable feeling that forgoing the speaker outs, and designing specifically for headphones, would yield a much better product for Head-Fi'ers.


Maybe.  Not sure what he planned to accomplish with the upgrade but perhaps he was chasing a certain type of sound and not necessarily a better performing amp on paper.  Personally, if I had the means to afford iron like that, I’d just have an amp built from the ground up to maximize their potential but….that’s just me.

It wouldn’t surprise me that building exclusively around headphones would have potentially made the 8900 sound “better” (for headphones).  But I personally feel that it incidentally beats out a lot of other headphone only amps despite being designed primarily for speakers.

I think you may just have a different design philosophy.  Just curious, what would you consider to be the best “reference” headphone amp you’ve heard so far?  Sounds like you might prefer something like a T4 (parafeed hybrid) amp by ECP audio.


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## Beefy (Aug 26, 2022)

Maven86 said:


> I think you may just have a different design philosophy.  Just curious, what would you consider to be the best “reference” headphone amp you’ve heard so far?  Sounds like you might prefer something like a T4 (parafeed hybrid) amp by ECP audio.



Depends on the phones. My Focal Clear and AMB M3 is by far my favorite *owned* combo. If I was ever going to build a big boy tube amp, it's got to be something that can accommodate sensitive low impedance phones like the Clear. So yeah, the T4 is probably much more my bag than the Elekit as currently available.

I suspect that if I had better high impedance low sensitivity phones than the HD650, the Elekit would be a no-brainer......


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## JamieMcC (Aug 26, 2022)

On the topic of Parafeed the Bottlehead Mainline was designed from the outset as a high performance parafeed headphone amp and it's a very nice sounding amp. There is a transformer upgrade rarely available (from Magnequest direct) that Bottlehead staff did unofficially support but it's a rather spendy custom Nickel autoformer, reportedly it's the dogs danglies.  However the trade off is you lose the low impedance setting on the Mainline.  

Fwiw the 8900 noticeably outperforms my Mainline and the Mainline is a superb sounding amp imo


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## Maven86 (Aug 30, 2022)

Beefy said:


> Depends on the phones. My Focal Clear and AMB M3 is by far my favorite *owned* combo. If I was ever going to build a big boy tube amp, it's got to be something that can accommodate sensitive low impedance phones like the Clear. So yeah, the T4 is probably much more my bag than the Elekit as currently available.
> 
> I suspect that if I had better high impedance low sensitivity phones than the HD650, the Elekit would be a no-brainer......


Just read your manifesto on the bottlehead forum.  Love the zeal but was a little surprised the Stratus caught your eye given Donald's design philosophy, especially compared to Elekit.

Anyhow, for one, it seems like you're specifically looking for a DHT build with transformers built to optimize headphones (e.g. multiple secondaries with loads for 32, 100, 300 ohm ect.)?  I can't think of any kits off the top of my head but check out Keenan's thread here where he did just that:

https://www.head-fi.org/threads/l0rdgwyns-diy-audio.921105/post-16696208

There are tons of circuits around and you can even have schematics made into PCBs if you know what you want.  In the example above, I believe he went to Electraprint to custom wind his transformers but there are a lot more options, you can even go parafeed if that's your thing.  As for a mega low impedance requirement...  you can have an OPT built with a tertiary winding to enable feedback (NFB)...

Designing something very close to what you want isn't the hard part...whether you'll end up liking the results of some of your design choices will be a different story.


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## lsantista (Sep 10, 2022)

Im about to place an order on the 8900 + the new 8550 pre. Ever since I listened to the 8200+8500 combo last year, with speakers and specially with 500 series senns (didnt have a higher series at the occasion) I was waiting for the opportunity to get an Elekit.
I would initially use it with a Holo Spring 3 that has a non bypassable preamp - DSD 128X: 2.9Vrms (RCA), 5.8Vrms (XLR) and PCM48 NOS:  5.8Vrms (RCA), 11.6Vrms (XLR). That would go to the TU8550 and then to 8900. I understand I don't need the 8550 having the DAC pre module, but I may part setups later, plus I want to try a tube pre on my amps, the 8550 does fit my budget and I dig the looks of the Elekit combo.  Also initially, plans are to use it with HD800 and small 8hm speakers with sensibility 88-90 (So Im guessing I will start with 300B). At some point (in life), I'd love to use it with bigger speakers with higher sensibility and also with a transformer box for estats as I love my Stax.

Has anyone here a stock or mostly stock 8900 to give impressions, specially after a few months of use? I want to do a few upgrades - this will be my first time building anything but I will have support, so I ask because Im still not sure what parts I will be able to ship to Brazil and how far I should go with more expensive parts, being a begginer.

Also, how easy/safe is to change AC voltage of this or another similar Elekit? I live in a 220-230V city, but most cities around are 110-120V and I may move next year. From what I gattered so far , specially from this at 6'50    , I will need to keep the other AC inlet unit and basically disassemble the amp's before having access to the AC unit? Would unsoldering and transfering the parts be a simple task with little risk of damaging anything? Is there any other (easier?) workaround to change AC after it has been built? Finally, I should not go for the extra big caps upgrade that dont fit on the cutoffs if I plan to be disassembling the amp, does that make sense?


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## lsantista

elekits ordered, will assemble with 220v units. finishing choosing tubes and a practice soldering kit 
Also, Im considering ordering custom transformers, maybe potted, output and power. Hoping anyone can pop in with the dimensions that would fit the 8900's top case and the mounting holes so no drilling is needed.


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## JamieMcC

Hi all, how time flies I've just realized my TU-8900 has been up and running for over a year now and am happy to report absolutely zero issues in the last 12 months.


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## Whitigir

JamieMcC said:


> Hi all, how time flies I've just realized my TU-8900 has been up and running for over a year now and am happy to report absolutely zero issues in the last 12 months.


From the foundation architecture of the 8900, it is solid and as reliable as a tank .  Thanks for reporting back!  I especially love that it can auto bias 2A3 or 300B


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## smodtactical

If anyone is interested in grabbing a TU8600S I have one for sale here: 

https://www.canuckaudiomart.com/det...-tu8600s-with-lundahl-opts-vcap-odam-tkd-pot/


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## JamieMcC

This popped up on my YouTube feed


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## Whitigir

JamieMcC said:


> This popped up on my YouTube feed



That is a wonder of diy Kit.  You can use whatever components you feel fit


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## JamieMcC

Lol the silver foil output cap conundrum has been festering away and reared its head again (to be honest the idea has been festering away for some time now). 

After reading about the Audionote silver foil capacitors and noticing they uses a Mylar dielectric it reminded me of another capacitor I've used in the past that also uses Mylar and that had a pretty unique sonic signature so just for giggles I've ordered some 0.1uf Russian K75-10  capacitors to go in the TU-8900 they are coming from Ukraine so delivery time might be interesting. 

I'm going to bypass them with the utterly fantastic Duelund JDM silver foil bypass caps just for a bit of fun to play about and mix things up a bit. Should make for a very different presentation from the Vcap Cutf!  

John L absolutely nails the sonics in his review of the K75-10

"I can report that K75-10 sounds extremely unique, quite different from K40Y PIO and any other true PIO one cares to mention, including Vitamin Q, Jensen, and AmpOhm. It has a very saturated, colorful, textured, and detailed midrange that is thick and juicy. While PIO’s are known for their natural and smooth midrange, K75 seems to add some jest, pop, and color to the proceedings, yielding an apparently more detailed and forceful presentation. Treble and bass is pretty good, especially for an oil cap, but the leading edges are not razor-sharp and precise like premium film caps. Since the midrange is so involving and palpable, the lack of equal force in treble makes it seem a bit dark overall, but as one increases the volume, this becomes less of an issue, and poorly-recorded music is much more tolerable at higher volume.

The sound is rather addicting in its presentation and can even be called delicious in what it does well, kind of reminiscent of biting into a ripe peach. The line dividing “colorful” and “colored” is thin, and while K75-10 likely leans a bit to the latter, I quite enjoy its substantial sound and prefer it to the thin, plasticky sound many other capacitors represent."


----------

