# Portable tube amp from china?



## voodoo do-er

what are your guys thoughts on this amp 

http://www.ebay.com/itm/Portable-Rechargeable-HiFi-Tube-value-vacuum-headphone-amplifier-amp-battery-SIL-/110925530276?pt=US_Home_Audio_Amplifiers_Preamps&hash=item19d3ad44a4

I almost want to buy one out of curiosity alone. but I know I probably should not

edit:
BTW don't go telling me what to buy or link a good amp 
I just want to know about this one.


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## Swimsonny

If you could get it and let us know thatd be great!


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## Spriggs

first i would like to say this is basicly a remake of the muse portable tube amp you can find another head fi post about that and I have just purchased this little bear and a ttvj millet hybrid tube amp and will be making a review and comparison


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## voodoo do-er

spriggs said:


> first i would like to say this is basicly a remake of the muse portable tube amp you can find another head fi post about that and I have just purchased this little bear and a ttvj millet hybrid tube amp and will be making a review and comparison



I thought it looked like a muse amp 

btw aren't muse stuff copy's, so it would be a copy of a copy ?


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## Spriggs

Quote: 





voodoo do-er said:


> I thought it looked like a muse amp
> btw aren't muse stuff copy's, so it would be a copy of a copy ?


 
  Yea, but i dont think ive seen this kinda amp before.


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## DogMeat

Reminds me a little of the Altoids box....


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## Spriggs

So the amp arrived today in the mail which took allmost 4 week shipping. and my first impressions werent great the little bear has a a horid pot and when ever you touch the thing it makes noise but as long as you dont change volume much during a song its fine. The sq at first was pretty murky and warmed up a little later (burn in/the tubes warming up) but all in all the sq isnt anything special. Now the build quality isnt amazing but it works, the tube heats up so much the whole amp feels like it will melt after like an hour or so. If you want a fun toy to mod this will be nice if you want a tube amp to listen to music with and have it sound a amazing go find a TTVJ portable hybrid tube amp.


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## voodoo do-er

thanks


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## supracuhz

Quote: 





spriggs said:


> So the amp arrived today in the mail which took allmost 4 week shipping. and my first impressions werent great the little bear has a a horid pot and when ever you touch the thing it makes noise but as long as you dont change volume much during a song its fine. The sq at first was pretty murky and warmed up a little later (burn in/the tubes warming up) but all in all the sq isnt anything special. Now the build quality isnt amazing but it works, the tube heats up so much the whole amp feels like it will melt after like an hour or so. If you want a fun toy to mod this will be nice if you want a tube amp to listen to music with and have it sound a amazing go find a TTVJ portable hybrid tube amp.


 

 Do you regret your purchase??


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## reddragon

Quote: 





spriggs said:


> So the amp arrived today in the mail which took allmost 4 week shipping. and my first impressions werent great the little bear has a a horid pot and when ever you touch the thing it makes noise but as long as you dont change volume much during a song its fine. The sq at first was pretty murky and warmed up a little later (burn in/the tubes warming up) but all in all the sq isnt anything special. Now the build quality isnt amazing but it works, the tube heats up so much the whole amp feels like it will melt after like an hour or so. If you want a fun toy to mod this will be nice if you want a tube amp to listen to music with and have it sound a amazing go find a TTVJ portable hybrid tube amp.


 
   
   
   
  what is the name of the ttvj portable hybrid tube amp? cant seem to find it...


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## Spriggs

the amp has promtly broken in its first night of use (tube blew due to bad circut design to much filiment voltage)and though i can say i regret my purchase but there are better things to spend your money on.


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## Spriggs

Quote: 





reddragon said:


> what is the name of the ttvj portable hybrid tube amp? cant seem to find it...


 
  They dont make them anymore and TTVJ Millet portable hybrid is the name you can try finding them on the for sale forum


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## reddragon

spriggs said:


> They dont make them anymore and TTVJ Millet portable hybrid is the name you can try finding them on the for sale forum




Thanks, how much is it and do you have it? If you do, hows the sound quality?


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## Spriggs

Quote: 





reddragon said:


> Thanks, how much is it and do you have it? If you do, hows the sound quality?


 
  i do have it and i have to say it sounds quite amazing better than the new ttvj's i say cause its warmer sounding much more tube like(probabbly cause there are real tubes) its also better than the alo audio continental also cause the alo does the tube part wrong(they did it in such a way the tube is rather usless and dosnt affect sound) now some one is going to disagree with me but that is my personal opinion. now on price not sure how much it goes for now. just patienly look on amplification for sale forum im sure one will come up eventually. Cheers


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## goodvibes

It's going to basically be something like this simple phase inverting ne5532 circuit with those electrolytic caps (c4, c8) coupling the output and a tube thrown in before the opamp. The tube serves no function other than giving you more coloration, complexity and neat factor.

  If you look at the battery, there's a single voltage rail which is why it will be this or a very similar circuit. There's no rail-splitter etc. The tube voltage will be too low while still getting too hot for that arrangement and besides the discomfort, imagine what the heat will do to the battery.


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## reddragon

spriggs said:


> i do have it and i have to say it sounds quite amazing better than the new ttvj's i say cause its warmer sounding much more tube like(probabbly cause there are real tubes) its also better than the alo audio continental also cause the alo does the tube part wrong(they did it in such a way the tube is rather usless and dosnt affect sound) now some one is going to disagree with me but that is my personal opinion. now on price not sure how much it goes for now. just patienly look on amplification for sale forum im sure one will come up eventually. Cheers





Not really looking for a portable tube amp even though the idea of it really intrigues me. In the future, I may be looking at a high end desktop tube amp that can drive almost anything. Any recommendation for the tube amp? I haven't set a budget for it yet but of course as high performance and low price as possible


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## Spriggs

if you want a desktop system you can go a couple ways i think there are a lot of companys that make desktop tube amps i havent heard many of them because my desktop system mainly consists of very high end speaker amp (which i made a impedance matching system for) and to me that sounds better than any thing else, now for cheapness and over all sound go build yourself a millet starving student(hybrid system with 12au7 tubes), ive made one for a friend and i have to say they sound pretty good for the price and it will drive pretty much anything, now if your not to good at diy and soldering buying a premade one off the forums might be your best bet and they usually are very well priced here.


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## Spriggs

Quote: 





reddragon said:


> Not really looking for a portable tube amp even though the idea of it really intrigues me. In the future, I may be looking at a high end desktop tube amp that can drive almost anything. Any recommendation for the tube amp? I haven't set a budget for it yet but of course as high performance and low price as possible


 
  first sorry about the double post but i have more to add. if you dont want to the millet you again can look on the amplification forums for reviews and people selling their stuff. but seriously the millet is quite a big bang for the buck.


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## reddragon

how much did it take you to build the amp? and i have no experience in diy.


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## Spriggs

It did not take me very much mainly because i had many of the parts just laying around so i cant give you a clear ammount but i think anywhere from 50-70 for a low end one and really high if you want to go over board but i dont recomend it. and if you have no experience in diy you can start but i dont know if point to point is a good place to start so maby read and look online for soldering instructions.


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## reddragon

ok thanks, i have no experience in diy and i dont think i will be good at that but i will look around


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## Nectar

Quote: 





spriggs said:


> the amp has promtly broken in its first night of use (tube blew due to bad circut design to much filiment voltage)and though i can say i regret my purchase but there are better things to spend your money on.


 
   
  I opened this thread, read China, ebay and tube amp and wondered what post would say it blew up.  The TTVJ Millet sounds interesting, think I read the parts became unavailable so it wasn't being made any more.


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## mrarroyo

I have had this amp for a bit over two months. As stated above it has too much current going to the valve so I replaced a resistor with a 20 ohm 5 watt one and the amp draws less current and runs a bit cooler. As a side benefit the amp run time has gone from about 3 hours to 4.5 hours. Next I tried op-amp rolling and replaced the NE5532 with: AD8620, AD797 (two to one board), and LM4562. Of those the AD8620 sounded the best but not necessarily better than the NE5532 just a bid differently. Next I will try the OPA2134.


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## Spriggs

Quote: 





mrarroyo said:


> I have had this amp for a bit over two months. As stated above it has too much current going to the valve so I replaced a resistor with a 20 ohm 5 watt one and the amp draws less current and runs a bit cooler. As a side benefit the amp run time has gone from about 3 hours to 4.5 hours. Next I tried op-amp rolling and replaced the NE5532 with: AD8620, AD797 (two to one board), and LM4562. Of those the AD8620 sounded the best but not necessarily better than the NE5532 just a bid differently. Next I will try the OPA2134.


 
  very nice ive done some similar mods but ive also upgraded the caps and the pot as you most likley know the pot is one of the worst i recomend an alps potentiometer they have one with the same specs and size as the one in the little bear.


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## penmarker

Quote: 





spriggs said:


> the amp has promtly broken in its first night of use (tube blew due to bad circut design to much filiment voltage)and though *i can say i regret my purchase* but there are better things to spend your money on.


 





 
	

	
	
		
		

		
		
	


	



   
  I'm sorry OP I just can't resist from laughing at this post.
  I feel bad for you man, hope we all learned our lesson from this thread.


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## Spriggs

Quote: 





penmarker said:


> I'm sorry OP I just can't resist from laughing at this post.
> I feel bad for you man, hope we all learned our lesson from this thread.


 
  lol first im not the op second it was actually really good for what it is, but you NEED and i stress this need to replace the potentiometer cause it sucks but once you do that and mabey some resistors it sounds pretty good for 70$


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## gikigill

I have ordered the same amp and will be changing the resistor as you've done however I am a noob when it comes to circuits and modifying.
   
  It would be great if you could give us some more info on how to mod this amp and the parts needed.
   
  Pretty cool to have a portable tube amp for $100 that sounds great.


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## voodoo do-er

penmarker said:


> I'm sorry OP I just can't resist from laughing at this post.
> I feel bad for you man, hope we all learned our lesson from this thread.



OP check.
yep, I'm the OP here.


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## MRiutort

Hi people
   
  I also bought this little bear B-1 hybrid amp looking for just that a hybrid portable amp. My one has the same problem with the power going into the tube filament. The original resistor should be 10 ohms and looks like a 2 watts one, but I take some voltage mesurements and something was wrong with it. So, I change it with 20 ohms 2 watts resistor and the voltage drop is very close the 6 volts needed for the filament. This was very important for the tube life and functionality. After this I just recharge the battery to full level and start using it. The amps is new and need more break in, but the sound is very interest for me. I like it more than the Fiio E07k because the warming tonalities. It really present a more tube like sound, not as flat as normal with the transistors. But the amp need attention, so it is not the buy now and used it for ever, no. This amp is more like a home made audio workshop proyect to play with.
   
  I have no too much information about battery durability or good or bad performance because I just bought the amp yesterday and work yesterday night with the resistor problem. So, almost 2 hours of use on it. The volulme control generate scratch sometimes and it runs a little hot, not burn to contact, but hot. It is powerful enough to drive strong the Sennheiser HD598 and sound good with new Apple earbud. Like the soundstage presented with the new Apple earbud. You need to remove the headphones when power on or off because the strong switch clic sound and it is afected with the iPhone 4s EMI. This is rare, because the box is complete in aluminum and I guess this help shielding it, but something happen. Of course this only happen when the phone is using the network for accessing data, at least that is what I notice for now.
   
  I drive it via Fiio line out adapter and direct from the headphone 3.5mm jack with nice sound results. The line out connection is better. The amps have a lot of power for my headphones. I never need to pass half the volume control position to listen strong my music with the line out connection. The sound presents hights limitations. I feel that the amps can not goes to the 20Khz normal response curve. For me it sounds like a 3 db drop beyond the 15khz, but I am guessing with this. Any way the highs are there, but attenuated. The mids range response is where the tube 3d sound stage magic present better. The musicians and sound separation is notable, not as wide as a normal tube amp, but the magic is present. The low bass also present problems. I can hear the bass, drums and chellos but not as tight as other amps here.
   
  I am still learning it, knowing his capabilities and limitations. The power supply need more revision, the 20 ohms 2W resistor is working hot to the limit. I am looking to modify it with a pulse dc to dc converter. Some ideas and regulators are in the evaluation process, but this need more experiment and time to play with.
   
  For me this purchase is a very good one. I know for sure that the amps need attention since new, so I do not regret the decision. That is what I was looking for a DIY proyect that is working but need some fine details to get better. The amps look very cool and the physical body shape is very confortable on hand. The sound capabilities are from normal to good with nice hybrid sound stage presentation that I really appreciate when listen to music. Solid state amps sound very clean but the sound stage 3d effect on the tubes make me very happy. This little bear is a very good in between point.
   
  Milton


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## psychmonster

picked this one up just recently...seems to have been upgraded...it actually has some warmth to it...nice bass responce...treble is clean...pots are clean...power supply was upgraded..
 Class A 12/6 series 6N11 12AU7 Tube valve vacuum Hybrid Headphone Amplifier  this is a decent amp...will upgrade to german tube...but out of the box am very happy...picked it up for $37 delivered from China on Ebay...went with the 12 instead of the 6....heat sinks do get hot....,but so far it rivals any of my output jacks on my vintage solid state amps


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## Skolar311

Quote: 





psychmonster said:


> picked this one up just recently...seems to have been upgraded...it actually has some warmth to it...nice bass responce...treble is clean...pots are clean...power supply was upgraded..
> Class A 12/6 series 6N11 12AU7 Tube valve vacuum Hybrid Headphone Amplifier  this is a decent amp...will upgrade to german tube...but out of the box am very happy...picked it up for $37 delivered from China on Ebay...went with the 12 instead of the 6....heat sinks do get hot....,but so far it rivals any of my output jacks on my vintage solid state amps


 
   
  This post doesn't tell us much unless you include the make and model of the amp. And $37? Don't know if I'd trust the quality/reliability of that. What kind of headphones are you running off this amp? Maybe provide some pics too?


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## Skolar311

I did a little more research and what you bought is a little bear.
   
  Be careful with that because I hear they get extremely hot and prone to failure. I read another little bear tube amp review where the unit only lasted 1 day of stress testing. I hope it works out for you and you enjoy it, but don't get terribly upset if the unit fails. That's probably part of the low price point.
   
  And also, that amp is not portable. So this is the wrong thread for your post.


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## gadget123

voodoo do-er said:


> what are your guys thoughts on this amp
> 
> http://www.ebay.com/itm/Portable-Rechargeable-HiFi-Tube-value-vacuum-headphone-amplifier-amp-battery-SIL-/110925530276?pt=US_Home_Audio_Amplifiers_Preamps&hash=item19d3ad44a4
> 
> ...


Little bear b-1 is from china
I just received 2 of these today,at 59 usd each
At 25%volume seems to be enough for most headphones
They sound very good for price,yes I have heard others
That cost more money that sound no better
They run a little warm,but not bad
And does have tube sound for sure
I heard them for 3 hrs + with all kinds of music
And yes at this point,I would buy more of them
But I have never heard a high end headphone amp yet
And as tubes go will sound a little better after gets more hours on tube
Would be a cheap way to hear a tube amp


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## keithsplace

I would go with the Little-Bear P5., I was trying to hold out for a little Dot MK5 but, can't budget it right now.
  The Little-Bear P5 is a two tuber, one for each channel. Actually, probably not even a comparison between them.
   
  Anyway I just got mine yesterday. Only on the second week since I paid on eBay from http://myworld.ebay.com/wfqxgw/&_trksid=p3984.m1439.l2754
   
  They shipped promptly with tracking that updated the next day.
  Don't expect any hugh difference ok. I paid like 27.00 with shipping and all.
  It is  different, but I figure there is a little tube burn in period, not sure cause it's been awhile
  since I have had anything with a tube in it. But have heard burn in is required, and some different tubes may yield
  different tone or quality. Like I said don't expect blowout difference in sound, it does seem to be a little more open, different nuances to the tonal quality, no that what I had was bad.
  But it is different, not sayin it's better or worse than the sound I get when I side by side with and without it.
  But I been running it for 24hours straight now.
   
*One NOTE: BEWARE* The included transformer that came with mine got extremely hot, to hot to touch in less than an hour.
  I sent them a message to ask it that was normal, well their store site message on eBay says they are away for a few days.
  But they did reply very promptly the first time I asked questions pre purchase.
  I have purchased stuff on eBay from China before, twice I think and this is the first thing I actually received and didn't have to get a PayPal refund.. The previous purchases tracking showed making  it into customs in NY but never showed up in my mail box.
   
  Ok I thought since the transformer was getting way to hot, so hot I have to leave it sitting in an ashtray on my bench to keep for scorching my bench. I thought I would look around the shop and see if I had something to use instead. I had an 18v as transformer as it the furnished. Only mine was much bigger and like 5 time the va rating, which I figured would be ok, voltage it the most important factor I thought, I thought wrong it worked great for 5 minuets, then pop, very loudly, not thought the sound. One of the caps had exploded it's innards all over the place, oops. Well looked it over cleaned up the stuffing's from the blown cap with alcohol and Q-tips
  and went to Radio shack for a new cap, it was a little tricky doing the replacement with these new surface and double layer projects, But I got it and it was back up and running in a few minuets. I went back to the furnished transformer for now, till I hear from wfqxgw.
  And see what value va is safe for the unit and no fire hazard.
   
  Final thoughts. Kinda wish I'd just waited for the Little Dot MKIV, but I like to tinker and thought this would be a good play toy, and cheap if I destroy it, I'm not out $200.
  Will post after some more burn in and time based review.


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## vkalia

Ha, I just bought the Little Bear BK unit from the same Ebayer, wfqxgw.    I dont really need it, as I have an E12, and an Alo National en route, but for $80, what the hey.
  
 Gonna see how it goes - will post a short report here once i get it.


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## Maxx134

I have it!
 temporarily I purchased for a friend who saw my Continental and wanted something similar and this is over 10x less ha but no way does is come close..
I still would put this little bear over most if not all cmoy amps as it has a nice warm sound with nice treble.
It is not as dynamic or large sounding as as my O2 or Continental, but those are my best so this comes in as a nice cheap amp that actually looks so cool and geeky as you see the tube so clearly lit!

Only real problems are:
Heat
Pop sound off when battery dies.
Pop sound when pulling out or pluging in cables.
Pop sound upon turn on
Heat, heat, and more heat..
Static dusty sound at low end of pot when adjusting volume.
Still the sound is very alluring..
If only it didn't have that nuisance pop..


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## manufelices

I have just bought one! Is it posibble to change the OAMP or the valve? Which type of valve does it use?


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## ag8908

I just paid $50 for a little bear p1 from china http://www.ebay.com/itm/Black-Little-bear-match-6N11-12AU7-6922-Tube-valve-HiFI-Headphone-Amplifier-AMP-/291095026438?pt=US_Pro_Audio_Amplifiers&hash=item43c69d9b06 .
  
 I'm expecting it to blow up on the first day and will use it in a big metal pot so that when it catches fire the pot will contain the flamed and prevent it from burning my desk down. I will also use an extension headphone cable so that it doesn't burn my HD800 I am a little concerned that it could ruin my HD800s in some other way, by sending a bad signal or something, but fortunately I'm still under warranty.
  
 As you can see I expect nothing and only got this for fun.
  
 It will be here in a few weeks. Should I order a bunch of additional bulbs? if so where? thanks


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## JW Santhem

maxx134 said:


> I have it!
> temporarily I purchased for a friend who saw my Continental and wanted something similar and this is over 10x less ha but no way does is come close..
> I still would put this little bear over most if not all cmoy amps as it has a nice warm sound with nice treble.
> It is not as dynamic or large sounding as as my O2 or Continental, but those are my best so this comes in as a nice cheap amp that actually looks so cool and geeky as you see the tube so clearly lit!
> ...


 
  
 I'm in the market for something like this, and the B-1 seems like a nice place to start. Only thing that worries me is the heat.
 How hot does this get? I'm addicted to the tube sound, but looking for something that will comfortably fit in my chest pocket...


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## ag8908

My little bear (linked above) came today. It seems to work fine and it's VERY powerful. More powerful than the objective 2 amp and I almost went deaf earlier when I accidentally had the volume at a level other than low. I'm not sure I hear the difference caused by the tube, sort of sounds a little more muddy maybe but that could be the amp itself? its glow looks cool though. no complaints in light of the price.
  
 It also hasn't exploded yet after 30 minutes of use.


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## ag8908

The left side is louder than on this amp, EDIT: But I fixed it by adjusting these orange screws near the bulb.


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## Svenna70

Got the B1 in the mail today. Got for around $35, including postage and handling. I didn't have very high expectations regarding the quality, but at this price I just couldn't resist.
 Fired it up right away, and could easily see that there was a way to high current on the filament. The whole tube was glowing bright orange, and it smelled burned almost instantly.
 Turned the amp off, and opened the casing. I replaced the 2W resistor, which in this case was measured to 0,1 ohms. Replaced it with a 22 ohm 5W resistor, and now the tube had a more "normal" glow. Another benefit from doing the mod was that now the hissing from the pot is far less prominent.
  
 All in all, a nice little toy, with a decent sound quality to it.


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## JennaFF

Has anyone used the latest version of these? I purchased one last night and the seller claims to have solved the overvoltage problem, among others.


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## thesheik137

I also recently ordered the Little Bear B3 portable amp and was wondering if you got yours and how it sounds.


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## JennaFF

I got mine. They are using a 12v to 5 volt adapter for the heater supply. I replaced it with a traco based heater supply and it works much much better. I plan on adding a new battery and a USB DAC in there too for use with my phone. I'm thinking about redesigning the PCB and having it so that I can just plug the DAC into that so I can easily upgrade. I also have a 6021 tube on the way that I want to try out. There is a channel imbalance I'm still trying to figure out the cause of. _ _I also drilled a hole in the tube PCB for a UV LED but I haven't installed it yet. It runs very cool, I can actually comfortably hold it in my hand with the tube window touching my skin.


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## JennaFF

I switched out the chinese tube for a 6021 from Thomson-CSF and the distortion at high volumes is gone, sound has a lot more clarity and the instrument separation is a lot better than before. All in all, it made much more of a difference than I expected.


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## thesheik137

Do you have a link for the tube? I got the little bear b3 recently and am loving it so far. I found it on Amazon for 50 and it's definitely worth it. Although it has a pretty terrible noise floor but it's not an issue when using less sensitive headphones.


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## ndburley

I got my B1 through the post today and have been playing with it. I am not getting too much heat off of it at the moment. The vendor said it was version 1.2
  
_In this version. upgrade 3 options:_
_1,Solved big "POP" wave noise problem, it was happen in  turn ON/OFF amplifier,current the POP noise is very lower. just like a clock tick sound. keep safe for your headphone_
_2,Solved the scratch noise,it was happen in you turn UP or DOWN the volume, current. that noise is gone_
_3,Improve the amplifier working time. because we improve the PCB circuit,change some parts. and the work time is up to 4 hours now.(before just about 2.5-3 hours)_
  

  
 There is a little pop when turning on and off but nothing major and listening to some female vocals at the moment it has warmed the top end. Liking it at the moment.
 I am a little worried about strapping a player to it as you will cover vent on one side and then if you have the player facing up the 2nd vent hole is on the desk.


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## PitBul34

thesheik137 said:


> I also recently ordered the Little Bear B3 portable amp and was wondering if you got yours and how it sounds.


 
  
 It sounds amazing with my iBasso dx90 + Audio-Technica ATH-W1000X full-size headphones or my Ultimate Ears Triple Fi 10 earphones. Soundstage is deep and airy, sound is very natural and clear!!!


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## jared basshead

I'm interested to get B3 as a portable self powerered tube amp for 85$ But was wondering is it could power dt990 600ohms. Can anybody chime in? I have already asked the seller and yet to get a reply from him


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## thesheik137

It should be fine as it provides quite a lot of power, although I never used it with 600ohm headphones. But I never went above half way on the volume pot when using with my hd-25s.


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## PitBul34

Sennheiser HD650 (300 ohm) works perfectly with the Little Bear B3.


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## golov17

How many hours of work Little Bear B3 with headphones 320 Ohm, and whether it can work if you connect the charger or the Power Bank? I found a thin 5V 5K mAh for him and I hope it can increase the time it works ..


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## PitBul34

golov17 said:


> How many hours of work Little Bear B3 with headphones 320 Ohm, and whether it can work if you connect the charger or the Power Bank? I found a thin 5V 5K mAh for him and I hope it can increase the time it works ..


 
 I didn't measure it, but my iBasso dx90 hi-res player out first. Yes, it can work via charger.


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## golov17

pitbul34 said:


> I didn't measure it, but my iBasso dx90 hi-res player out first. Yes, it can work via charger.


 nice  how it sounds with a variety of DAP and DAC?


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## PitBul34

I prefer dual to mono opamp module AD825AR instead of NE5532 (Little Bear B3 factory installed), however NE5532, OPA2604, PA627AU sounds pretty good too. Factory installed tubes are good old USA made Sylvania.


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## PitBul34

golov17 said:


> nice  how it sounds with a variety of DAP and DAC?


 

 FiiO X5 sounds terrific with LB B3. I don't really know about others, but i think all gonna be OK.


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## golov17

pitbul34 said:


> FiiO X5 sounds terrific with LB B3. I don't really know about others, but i think all gonna be OK.


Thanks for opinion, man


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## golov17

Nice


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## Maxx134

pitbul34 said:


> I prefer dual to mono opamp module AD825AR instead of NE5532 (Little Bear B3 factory installed), however NE5532, OPA2604, PA627AU sounds pretty good too. Factory installed tubes are good old USA made Sylvania.



Earlier in this thread, .I posted how I had the B1 and also an expensive money ALO portable tube amp...

I have neither now and miss them, 
So I ordered the latest dual tube model you have in silver.

Once it arrives, I will post how it compares from memory of other, plus my O2, if I still have that,
because I not care about that one and it stayed in closet for over a year..


----------



## Maxx134

I just checked that and bought that opamp,
But I see there are also other opamps which I have no clue if there is any better.


----------



## Maxx134

Update an ebay seller have this dual tube unit at a new lower price!:


But they say it is a "B-4" model!!
Could be a typo?

Here is link!:
http://pages.ebay.com/link/?nav=item.view&id=252344492743&alt=web


----------



## golov17

this not from 5V micro USB, and it not work when connected to the charger


----------



## Maxx134

Wew! 
I lucky I didn't buy that one!


From looking at pics of the board posted earlier,

I see very good parts and it does look like it can match or beat the competition out there. .

The opamp is a..
 *Edit*
Looking into it but looks like suggested opamp is way superior to conventional one.


----------



## magisterarus

Buy B4 model instead of B3 would be a better choice.
 In fact B4 is the updated version of the B3.
 They have changed the charge from the original USB to 12V direct supply  (and so battery from 3.7V to 12.6V) to eliminate the noise floor due to the DC-DC step-up converter module.


----------



## lbbef

I have the B1+ and the B4 (as well as another random more expensive China tube amp).

Got then direct from their China web store on Taobao (China online shopping website). Will post up the details, difference etc between the models when I get home on Monday.


----------



## golov17

lbbef said:


> I have the B1+ and the B4 (as well as another random more expensive China tube amp).
> 
> Got then direct from their China web store on Taobao (China online shopping website). Will post up the details, difference etc between the models when I get home on Monday.


Very well


----------



## ryanjsoo

I was really interested in the B1 portable tube amp and tried to mod one out, unfortunately I don`t have the time now to complete the project so all the parts are up for sale. The amp works and comes with many extra parts/components, but something is not grounded properly. You can see the ad in my signature, feel free to send me offers if you think the price is steep.


----------



## Maxx134

magisterarus said:


> Buy B4 model instead of B3 would be a better choice.
> In fact B4 is the updated version of the B3.
> 
> They have changed the charge from the original USB to 12V direct supply  (and so battery from 3.7V to 12.6V) to eliminate the noise floor due to the DC-DC step-up converter module.



I already paid more for the older model which cost 20 more.
They say in the details that they corrected some noise issue and that it was the latest version.

But Looks like now this cheaper version labeled B4 is the true latest version. 

I hope mine don't have any noise floor.

I actually prefer that mine can be used while charging..

I will compare it to my O2 amp.

The winner stays and the looser goes..


----------



## golov17

LB3 test autonomy with 150 Ohm beta Asura 8,5 hours


----------



## Maxx134

Update, 
I now have the *last* version of the B3:
version 1.4 - Dec28,2015 ...



It is *NOT* the latest B4


 and can confirm this unit can play while plugged in,
And it charges off a micro usb plug,
and there is zero hiss or noise.

At first turn on, there is a slight noise floor and the right side tube starts first. 
That clears up to a magnificent sound! 

This is not a "tubey" sound like the B1, or the expensive ALO tube amp I had in past.

I am very suprised at the neutral clarity and freq response up in the treble range I heard. ..

The only issue was the power. .

It is not as powerful as the older units, or my O2 amp either...

Yet it runs very cool!!
It eventually gets warm though, but that's it.

My unit has Raytheon labeled tubes inside, 
Which probably they use whatever they have.

I must admit this unit at low and normal volumes sound simply excellent,
Superior in soundstage and realism to my O2 amp!..!!

The O2 had detailing, but falls flat on the background soundstage. 

This B3 is more resolving of background string instruments, and background distance localization. 

Piano sounds more layered, while O2 had a flatter , more upfront sound. .

I am talking in general minute differences which otherwise less critical listeners would choose the O2 amp simply because it has more volume/power.

This B3 will start to have distortion past 2/3 way up the dial, and at that point is equivalent to half the dial on my O2 with maximun gain button pushed in.

The O2 also will distort past 2/3 setting, but it is louder.

Both units were tested with an Oppo PM2,
So they both had a demanding load.

I am sure a normal dynamic headphone will not be a problem with these amps..


----------



## Maxx134

pitbul34 said:


> I prefer dual to mono opamp module AD825AR instead of NE5532 (Little Bear B3 factory installed), however NE5532, OPA2604, PA627AU sounds pretty good too. Factory installed tubes are good old USA made Sylvania.




Popping in the recommended chip improves clarity of the lower region and improves clarity of bass.



The unit seemed less thick or bassy,
but I touched the tiny silver pots to boost the tube volume a bit.

Edit:
I see they changed two caps in middle next to the opamp,
 from a mica to an electrolytic. 
Looks like something to look into .


----------



## Maxx134

Also, the DC to DC step up board has three caps instead of only two in the past.
It may be the "noise floor" solution they implemented so I will post pics later.


----------



## Maxx134

magisterarus said:


> Buy B4 model instead of B3 would be a better choice.
> In fact B4 is the updated version of the B3.
> 
> They have changed the charge from the original USB to 12V direct supply  (and so battery from 3.7V to 12.6V) to eliminate the noise floor due to the DC-DC step-up converter module.



I am believing the reason may be due to both added expense or durability of this usb power board,
Plus I believe the unit has less volume or power than the old units because of this..


----------



## magisterarus

It was not only my assumption, but what the same Little bear declares in this regard, on B4 details in Taobao store (this is obviously a google translation from Chinese):
  
_"Important Update: the original USB charging direct charge to 12.6V charge. Mainly to solve the background noise. Previous booster plate difficult to do without the noise floor. _
_It can only be changed to 12V battery direct supply. No aspect of the original USB charging convenience. But in order to enhance the sound quality. This is worth it. Because a full charge can be used 4-5 hours. Is enough demand to go out to listen to music, do not need to charge with USB listen listen"._


----------



## Maxx134

Yes their decision was a proper, and financially smart one to move away from the over achieving unit I have.

Quote:
"*Previous booster plate difficult to do without the noise floor.*"

It was difficult to do but they did fix it..

Yet, it end up being more difficult and costly, 
as they have added TWO boards(!)..
ONE on each side...












Plus the fact they are correct in saying the battery life is more on latest unit with larger battery at higher voltage. 

It also my belief that it has more power for louder volumes than my unit.

So the compromise of having higher technology in mine with USB and smaller battery, was in the end not practical.

Having bigger longer lasting battery and normal charger is better way to go.


I do like the convenience of this usb unit, 
but rather have the added power in volume that a larger battery will bring and they not saying.

The noise floor issue is a blatant excuse,
 as it is totally solved in my unit..

Maybe future units will have a better implementation of this usb,
But bottom line it is not really necessary in this type of device. .


----------



## golov17




----------



## Orestes1984

Any idea on what the B5 sounds like? It's a shame you can't change the tubes which is the whole point of going to valves.


----------



## AudioNewbi3

Sorry for thread necrophilia , but I just bought the little bear B4 from thier official Taobao Store :
https://item.taobao.com/item.htm?spm=a1z09.2.0.0.fwnzTy&id=521357511794&_u=g2i926dja54e 
  
 The last update for the b4 tube amp was on the 9th of June 2016, where the PCB was slightly redesigned to improve efficiencies as well as omitting the cut outs on the acrylic panel as the new 5899 Tubes were deemed to operate at a lower temperature as well as to prevent dust particles from entering the amp.
  
 Also, as suggested by Chinese users, I have also purchased the AMP9920AT to use in the B4 which has been mentioned to improve detail and overall sound-staging
https://item.taobao.com/item.htm?spm=a1z09.2.0.0.825KRe&id=35207043173&_u=g2i926dj2a8f


----------



## AudioNewbi3

orestes1984 said:


> Any idea on what the B5 sounds like? It's a shame you can't change the tubes which is the whole point of going to valves.


 
 According to thier Taobao store:
 B4 has 3 hours of battery life while B5 has 6-8 hours
 Microphonics is more severe in the B5
 B4 uses 5899 tubes vs B5 which uses 6418 tubes 
 B4's reconmended impedance load is 16~200Ohms vs B5's 16~100Ohms
 B4 has a better noise floor than B5
 B5 has rollable opamps whilst B5 do not


----------



## TwoPalms

B5 is not for sensitive multi BA earphone. Too much noise.


----------



## TwoPalms

Glowing Red!


----------



## AudioNewbi3

twopalms said:


> Glowing Red!


 
 Actually, the tubes themselves are not glowing. It is the led beneath them that is doing all the glowing.
 The tubes themselves draw only very little power and thus will no glow and produce sufficient amounts of heat.


----------



## bzfrank

Got my Little Bear B4 today. I am positively surprised. Its quite good actually, after a few minutes warm up. I consider it an update to the stock X3 amp with a quite likeable, warmer sound signature, even with the default opamp. It is not getting hot either, so no problem handling it.


----------



## AudioNewbi3

bzfrank said:


> Got my Little Bear B4 today. I am positively surprised. Its quite good actually, after a few minutes warm up. I consider it an update to the stock X3 amp with a quite likeable, warmer sound signature, even with the default opamp. It is not getting hot either, so no problem handling it.


 
 How do like it with your X3? I am going to use it with my Xduoo X3 too


----------



## golov17

http://s.aliexpress.com/IvuIBnum


----------



## bzfrank

Its surprisingly good - It makes the TK13 really sing on the X3. To my (prefering a warmer signature) ears much better than the stock X3 amp which I consider (too) bright and harsh for these IEMs. A tad more noise floor, but not too bad. Need to check with other earphones and the monitors though.
  
 I purchased the B4 only out of curiosity, but I think it will keep its place in my collection. It also has such a nice glow.


----------



## AudioNewbi3

bzfrank said:


> Its surprisingly good - It makes the TK13 really sing on the X3. To my (prefering a warmer signature) ears much better than the stock X3 amp which I consider (too) bright and harsh for these IEMs. A tad more noise floor, but not too bad. Need to check with other earphones and the monitors though.
> 
> I purchased the B4 only out of curiosity, but I think it will keep its place in my collection. It also has such a nice glow.


 
 Oh man! Can't wait for mine to arrive now!!!!!!
 Wonder what an upgraded op amp will do to the sound? (AMP9920)


----------



## golov17

Indonesian


----------



## AudioNewbi3

golov17 said:


> Indonesian


 
 I remember see that tube amp somewhere on kickstarter.
  
 Any more info?


----------



## golov17

audionewbi3 said:


> I remember see that tube amp somewhere on kickstarter.
> 
> Any more info?


only pic


----------



## magisterarus

audionewbi3 said:


> I remember see that tube amp somewhere on kickstarter.
> 
> Any more info?


 
https://www.kickstarter.com/projects/970055861/hybrid-valve-headphone-amplifier
  
http://www.ims-nz.com/


----------



## bzfrank

A comparison with the B4/B5 would be nice. 
	

	
	
		
		

		
			




  
 BTW:
  
 One thing that bothers me a bit with my B4 is a rather loud on/off click in the headphones, its not device killing loud but annoying. Anyone noticed the same?


----------



## gwompki

Just curious if anyone has tried this am with fostex t50rp mkIII or sennheiser hd600/650. Hoping it has enough power because I love the mod and opamp rolling potential.


----------



## golov17

gwompki said:


> Just curious if anyone has tried this am with fostex t50rp mkIII or sennheiser hd600/650. Hoping it has enough power because I love the mod and opamp ring potential.


use this with Seahf LD3.0 400 Ohm, normal


----------



## gwompki

Thanks Golov! I can order mostly risk free from amazon. It's down to that and the Fiio e12 on sale at B&H. I think the the b4 might be better for me since most headphones I will be driving are under 64 ohm. I hear the noise floor on the e12 is high on low impedance phones.


----------



## golov17

gwompki said:


> Thanks Golov! I can order mostly risk free from amazon. It's down to that and the Fiio e12 on sale at B&H. I think the the b4 might be better for me since most headphones I will be driving are under 64 ohm. I hear the noise floor on the e12 is high on low impedance phones.


btw, hiss - this problem with low-ohms earbuds.. with cheap tube amp


----------



## gwompki

Good looking stack!

Fair enough on the hiss. Just curious have you ever tried the Fiio e12? I wonder how it compares in terms of noise floor. 
I think I can live with some hiss for the price and the fact that I can roll op amp. Plus I can easily modify since there are no smd components. I hate not being able to repair audio gear.


----------



## golov17

gwompki said:


> Good looking stack!
> 
> Fair enough on the hiss. Just curious have you ever tried the Fiio e12? I wonder how it compares in terms of noise floor.
> I think I can live with some hiss for the price and the fact that I can roll op amp. Plus I can easily modify since there are no smd components. I hate not being able to repair audio gear.


 not tried any Fiios, but i have other amps


----------



## gwompki

Does anyone use this amp with their cellphone? Most of my listening will be Spotify through my phone and I started worrying about emi. The product description recommends moving the amp far away from the phone and not sure that would work for me.


----------



## AudioNewbi3

gwompki said:


> Does anyone use this amp with their cellphone? Most of my listening will be Spotify through my phone and I started worrying about emi. The product description recommends moving the amp far away from the phone and not sure that would work for me.


 
 The amp is extremely poor at insulating/isolating itself from RMI/EMI......so yeah get the signal generating devices as far away as possible.


----------



## AudioNewbi3

That akward moment when your portable tube amp has a wider soundstage than your solid state as well as having an overall better performance....


----------



## gwompki

audionewbi3 said:


> That akward moment when your portable tube amp has a wider soundstage than your solid state as well as having an overall better performance....


 
 Just saw your post over on the Ear Buds round up thread.  You might have convinced me to pick one up after all.  Any idea how far I would need to move the cell phone from the amp? 1 meter perhaps?  Your description of it sure makes me want to try it.  How does it sound with the Seahf 320 ear bud?  I'm thinking about picking up a set of those.
  
 I bought a Fiio E12a as a trial and so far am happy with it, but I really like the price of the Little Bear B4 plus the fact that I can experiment with op-amps.  Decisions decisions


----------



## AudioNewbi3

gwompki said:


> Just saw your post over on the Ear Buds round up thread.  You might have convinced me to pick one up after all.  Any idea how far I would need to move the cell phone from the amp? 1 meter perhaps?  Your description of it sure makes me want to try it.  How does it sound with the Seahf 320 ear bud?  I'm thinking about picking up a set of those.
> 
> I bought a Fiio E12a as a trial and so far am happy with it, but I really like the price of the Little Bear B4 plus the fact that I can experiment with op-amps.  Decisions decisions


 
  
 As far as pushing high impedance buds go, I have not tested it out yet. However, official spec sheets over at Taobao claims that the amp is only good for 16~200Ohms. As for how far does cell phone need to be, I tested mine and 0.5 meter seems to be fine.


----------



## gwompki

Thanks.  That's odd that it lists max load of 200 ohms.  On Amazon they list 16-400 ohms, but yeah on ali and taobao they list 16-200 ohms.  Power output is listed at 450mW, but doesn't specify the load they are using to achieve that.  
  
 If you ever get a chance to test with the Seahf 320's let me know! I'm very interested.


----------



## MIKELAP

audionewbi3 said:


> That akward moment when your portable tube amp has a wider soundstage than your solid state as well as having an overall better performance....


 
 Been debating getting the usb charging model or the $60.00 power supply model would use it with 16 ohm buds The main question is ,.is this amp worth buying in your opinion ,hows the build quality.Whats the battery life like on this amp 2-3 hours or more


----------



## AudioNewbi3

gwompki said:


> Thanks.  That's odd that it lists max load of 200 ohms.  On Amazon they list 16-400 ohms, but yeah on ali and taobao they list 16-200 ohms.  Power output is listed at 450mW, but doesn't specify the load they are using to achieve that.
> 
> If you ever get a chance to test with the Seahf 320's let me know! I'm very interested.


 
  
 Will do.


mikelap said:


> Been debating getting the usb charging model or the $60.00 power supply model would use it with 16 ohm buds The main question is ,.is this amp worth buying in your opinion ,hows the build quality.Whats the battery life like on this amp 2-3 hours or more


 
 Build quality is solid. At least my B4 is. If I were you I would get the DC charging version as the noise floor is significantly reduced due to the simplified PSU.
  
 As for battery life for my B4,  official Taobao store quoted an operating time of 3~4Hours. Tube will get warm but not hot.


----------



## gwompki

golov17 said:


> use this with Seahf LD3.0 400 Ohm, normal




Golov, how is the performance of B4 with high impedance ear buds. I am interested in Zen 2 and Seahf 320 ohm.


----------



## AudioNewbi3

gwompki said:


> Golov, how is the performance of B4 with high impedance ear buds. I am interested in Zen 2 and Seahf 320 ohm.


 
 Think he is double amping, using one amp for power whilst the B4 mainly for sound change.


----------



## golov17

in fact, it has enough power to run nearly 400 Ohm at maximum volume


----------



## AudioNewbi3

gwompki said:


> Thanks.  That's odd that it lists max load of 200 ohms.  On Amazon they list 16-400 ohms, but yeah on ali and taobao they list 16-200 ohms.  Power output is listed at 450mW, but doesn't specify the load they are using to achieve that.
> 
> If you ever get a chance to test with the Seahf 320's let me know! I'm very interested.


 
  
 So I tried it with my SeaHF V1 320Ohm today and I must say, the amp did struggle to drive them on my normal Xuduoo X3 settings (RB'ed).
 My normal LO volume is -25db and with this the volume knob of the b4 had to be turned to 12 oclock to drive the 320Ohms
 Switching the LO volume to -15~-10db solved the issue and the volume pot can comfortably sit at 10 o'clock to drive the 320Ohms. 
  
 Maybe due to placebo effect, I did think the lower end sounded a wee bit "muddied"


golov17 said:


> in fact, it has enough power to run nearly 400 Ohm at maximum volume


 
 Your's is the b3 whilst mine is the b4 so I think there maybe some difference mate!


----------



## gwompki

Thanks for the impressions!  They are much appreciated.  It sounds like even though it might not be ideal, overall the amp will probably meet my needs.  Great news.  I think I will order today.


----------



## AudioNewbi3

gwompki said:


> Thanks for the impressions!  They are much appreciated.  It sounds like even though it might not be ideal, overall the amp will probably meet my needs.  Great news.  I think I will order today.


 
 No problem mate


----------



## Maxx134

bzfrank said:


> Got my Little Bear B4 today. I am positively surprised. Its quite good actually, after a few minutes warm up. I consider it an update to the stock X3 amp with a quite likeable, warmer sound signature, even with the default opamp. It is not getting hot either, so no problem handling it.



Edit: woops sorry I have B3 unit:

I have updated my B3 opamp and noted improvement.
Although it is not as powerful as my O2 amp, I still like the sound better.
The O2 need to have it's op-amps rolled to sound optimal.

Although I love the B3, I like to test the newer units so anyone like the B3 PM me.
Edit the B3 has the USB charging , 
While the B4 has normal charging.
B5 look nice but obviously weaker.

Also, I believe all these units can have their opamps swapped for more sonic options.


----------



## MIKELAP

Regarding the B4 any distortion issues if over driven 
*Pros:* Transparency, build quality, portability, use with iOS (special cable required), DAC resolution, sound quality, aesthetic appeal
*Cons:* Valves distort if over driven (line in source needs to be variable), low powered for higher impedance cans, no way to turn off USB charging.


----------



## gwompki

I ordered the B4 yesterday. Now the 2-3 week wait begins. Looking forward to experimenting with it. Looking forward to opamp rolling and building a module to make tube swaps easy(ish).


----------



## bzfrank

Yep, matches my experience:
  
 B4 Pros:  
  
 - Sound is good (for low impedance headphones/IEMs and moderate levels)
 - Amps can be easily rolled
 - Price
 - Nice glow
  
 B4 Cons: 
  
 - Click noise when turning on/off
 - Limited RF resistance (mobile phone transmissions are audible when stacked)
 - Limited Power (cannot drive high impedance headphones), distortion when over driven, variable source needed
 - Need separate 12V charger


----------



## gwompki

My B4 arrived today. Initial impressions are really good. Much smaller than anticipated. Packaging is very minimal, but who cares. 


After 2 hours of use here is what I can say confidently. 

-much smaller and lighter than I expected
-powering 320 ohm ear buds (Zen 2.0) with authority
-unit is slightly warm after an hour but definitely not hot
-rf interference is minimal. I have my phone back to back with the the b4 right now and do hear some noise between tracks but not much. Move it slightly and it's gone entirely
-battery life seems good so far but only 2 hours in.

I am impressed so far. Can't wait to roll op amps and listen more.


----------



## MIKELAP

gwompki said:


> My B4 arrived today. Initial impressions are really good. Much smaller than anticipated. Packaging is very minimal, but who cares.
> 
> 
> After 2 hours of use here is what I can say confidently.
> ...


 
 Any distortion if overdriven ?


----------



## gwompki

mikelap said:


> Any distortion if overdriven ?




So far my phone has not been able to make them clip at max volume. Im guessing if I had a real dap with more power I would be getting some clipping.

On the opamp front so far I have tried two others than stock:

LM4562 - made everything waaay too warm but pretty good sounding regardless. I feel like some of the dynamics might have been lost.

Opa2107 - slightly warmer than stock. Better overall dynamics. Both lows and highs sound much better. Highs not as shrill. Really like this one.

I plan to try a muse02 and opa2134 soon, but letting my ears adjust to opa2107 first


----------



## gwompki

audionewbi3 said:


> Sorry for thread necrophilia , but I just bought the little bear B4 from thier official Taobao Store :
> https://item.taobao.com/item.htm?spm=a1z09.2.0.0.fwnzTy&id=521357511794&_u=g2i926dja54e
> 
> The last update for the b4 tube amp was on the 9th of June 2016, where the PCB was slightly redesigned to improve efficiencies as well as omitting the cut outs on the acrylic panel as the new 5899 Tubes were deemed to operate at a lower temperature as well as to prevent dust particles from entering the amp.
> ...


 
  
 I've been enjoying my B4 for a few days now.  Just curious what you thought about the AMP9920AT OP-Amp?  I see they can be had for around 30 dollars US which I would consider.  Right now I'm enjoying both the LM4562 (even though initially I thought it was too warm) and OPA2134.  I think I might have fried my OPA2107 through ESD


----------



## AudioNewbi3

gwompki said:


> I've been enjoying my B4 for a few days now.  Just curious what you thought about the AMP9920AT OP-Amp?  I see they can be had for around 30 dollars US which I would consider.  Right now I'm enjoying both the LM4562 (even though initially I thought it was too warm) and OPA2134.  I think I might have fried my OPA2107 through ESD




I think the AMP is a great Op Amp. Problem is, the b4 will loose some of its "tubiness" at least thaf is what I think. Kindly note that I have only use the stock op amp for like 1min before switching and sticking with the AMP.

Details is good and soundstaging maybe slightly extended.


----------



## MIKELAP

So far how would you guys rate  the B4 portable tube amp is it worth buying ? Is it money well spent, or is it better than nothing


----------



## gwompki

I think its still too early for me to say.  I will say this.  I certainly don't dislike it.  It definitely adds a really nice dimension to the music I'm listening to.  I can't put my finger exactly on what yet, but going back and forth between say phone > headphones and then phone > b4 > headphones I'm definitely enjoying the b4 more.
  
 Couple of things I have noticed.
  
 -I think (could be wrong) but the amount of amplification it is actually doing is fairly minimal even on low impedence headphones.  For instance if I crank my source 1 click above mute, and put the amp at full power the headphone output is barely any louder out of the amp than it is straight from the source.  Could be that this isn't a valid test, but when I had a.   Fiio E12A and did the same test, the volume got significantly louder.  I think this amp excels being able to a add touch of tube flavor followed by the op-amp of your choice that really fills out the sound.  So its not a buffer in the strictest sense of the word, but I really don't think its that much of an amp either in terms of actually amplifying haha.  For instance, my laptop, while actually fairly powerful is really cold sounding.  Running my headphones through the B4 drastically improved the sound, but certainly is not making things any louder.
  
 -The two tubes each have two trim pots in line that control voltage to pins on the tube that I did not bother to trace.  I was impatient and decided to turn them slightly and noticed the sound got noticeably "tubier".  I think from the factory they had been set to run really cold so I cranked them up a bit.  I have noticed now that the RF interference is much more noticeable with my phone sitting on top of it, but goes away if I move the phone about 12 inches away.
  
 -So far I still have not been able to get this thing to distort even running the input at full volume.  I'm wondering if there was a design change to address this issue.  Mine has a PCB dated June 2016.  Also thinking if this sort of design change did take place if that could explain the perceived lack of amplification.  Anyone want to share resistor/cap values from previous versions?   I'd love to see a schematic, but I'm sure Little Bear won't want to share.  
  
 In a nutshell...I'm glad I got it.  It does sound good...just has a few things that are keeping me puzzled.  My mind is a little restless about these sort of things and sometimes I can't just enjoy a product for what it is until I can figure out things like this.


----------



## penmarker

Little Bear had moved up their quality control I guess, though their products do bear resemblance to some other branded amps/preamps. The analog community is abuzz with their phono preamp that compares to higher tier ones - with only drawbacks coming from cheaper components to lower the prices. Though they do offer matched components, emi isolators, upgraded circuits, and better toroids at higher prices to those who chooses to. You can find the different options in eBay.
  
 Cheap but good audio quality gears, what a time to be alive!


----------



## AudioNewbi3

The B4 to me has good build and sound quality. IMHO I am personally very satisfied that I bought them.


----------



## gwompki

Guys, I have to say after a few more days that I think I'm going to let the b4 go. I've been listening to my VE Zen 2.0 almost nonstop and I have come to the conclusion that for me they really dont do well with tubes. My desktop setup is also a tube hybrid and I much prefer the sound straight from laptop. However the b4 sounds awesome with my lower impedance buds like monk plus and auglamour rx1. I had heard that the Zen 2.0 was picky and to my ears it's just not a good match.

Think I want to buy a fiio e12 or e12a which I had previously. I'm not 100% sure yet but after a week that is the way I'm leaning. Might just keep it for travel purposes but I really enjoyed the fiio. Decisions decisions.


----------



## golov17

gwompki said:


> Guys, I have to say after a few more days that I think I'm going to let the b4 go. I've been listening to my VE Zen 2.0 almost nonstop and I have come to the conclusion that for me they really dont do well with tubes. My desktop setup is also a tube hybrid and I much prefer the sound straight from laptop. However the b4 sounds awesome with my lower impedance buds like monk plus and auglamour rx1. I had heard that the Zen 2.0 was picky and to my ears it's just not a good match.
> 
> Think I want to buy a fiio e12 or e12a which I had previously. I'm not 100% sure yet but after a week that is the way I'm leaning. Might just keep it for travel purposes but I really enjoyed the fiio. Decisions decisions.


Topping nx5 very well for Zen2.0, IMHO


----------



## gwompki

OK...I was being too hasty last night. Just tried it with the original monk ear bud and found the pairing I was looking for. Will definitely be keeping the b4 for now. Got my travel rig sorted


----------



## gwompki

Impressions after another 7 days with the b4 listening every single day:

I finally went back to the stock op amp. Surprisingly it's neutrality really seems to help this amp overall. Now when it is paired with the Ve Zen 2.0 from the right source it sounds great. I still haven't tried my muse02 in this amp yet but am curious how it would perform.

One problem I discovered that made me think this might not be a good amp for me was that my current phone when amped only improves the sound for certain buds. This is due to my phone's sound being fairly colored. When amped from my phone with the b4 things became very muddy for many records. However on my laptop and old phone the sound is quite neutral and thus becomes a good match for the b4. 

It seems if you have a source with decent power and neutrality, the b4 will add a hint of warmth and expand the soundstage. I'm still not convinced of its amplification claims but it definitely has improved many recordings from a variety of different headphones when used with the right source.

My thoughts of selling it last Saturday have completely subsided. I'm sure I might sell it some day but not now.


----------



## gwompki

I put the Muses02 opamp in today. Very nice improvement in soundstage. Seems like overkill for this little amp but definitely a nice improvement. I'm thinking of trying a pair of the opa627au. Has anyone ever tried that configuration?


----------



## T.R.A.N.C.E.

I get high noise floor from B4 and some crackling through left channel with B4, and if I flick the vol knob or my iem cable I hear "ting" sounds through the b4.
  
 For me B4 is a waste of money so far.


----------



## bzfrank

The B4 is very EM sensitive - both over its line-in and even radiation (e.g. mobile phone).


----------



## Subhakar

Could someone suggest a portable tube amp for sensitive IEMs at around $200 that can perform a bit less than ALO Continental that is too pricey at $700?


----------



## gwompki

t.r.a.n.c.e. said:


> I get high noise floor from B4 and some crackling through left channel with B4, and if I flick the vol knob or my iem cable I hear "ting" sounds through the b4.
> 
> For me B4 is a waste of money so far.




I use the b4 with ear buds that for the most part are 64 ohms and over so the hiss isn't much of a problem for me.

The "ting" sounds are normal. The sub mini tubes are slightly microphonic by nature. The seller I purchased from disclosed this up front.

The -rf interference was also disclosed by seller. It mentioned if you use a phone or wifi enabled device you will hear some noise with devices stacked. The noise for me is minimal but if I move it about half a meter the noise is gone.


----------



## gwompki

subhakar said:


> Could someone suggest a portable tube amp for sensitive IEMs at around $200 that can perform a bit less than ALO Continental that is too pricey at $700?




I think the b4 is pretty good bang for your buck but I have also seen this one

http://www.thetubestore.com/Parts-Accessories/Amps-and-Amp-Kits/Hybrid-Valve-Headphone-Amp

They also make a version with built in dac
http://www.thetubestore.com/Parts-Accessories/Amps-and-Amp-Kits/Hybrid-Valve-Headphone-Amp-Dac

I would love to try one but not in the budget right now. Unfortunately I haven't seen much written about these.


----------



## harpo1

gwompki said:


> I think the b4 is pretty good bang for your buck but I have also seen this one
> 
> http://www.thetubestore.com/Parts-Accessories/Amps-and-Amp-Kits/Hybrid-Valve-Headphone-Amp
> 
> ...


 
@Brooko Reviewed those.
  
 Edit:  Here's a link to his review.
 http://www.head-fi.org/products/ims-hybrid-valve-headphone-amplifier-hva/reviews/15617


----------



## penmarker

subhakar said:


> Could someone suggest a portable tube amp for sensitive IEMs at around $200 that can perform a bit less than ALO Continental that is too pricey at $700?


 
 For a good performing amp which is 1) portable 2) tubed 3) for sensitive IEMs, $700 is a fair price.


----------



## Subhakar

penmarker said:


> For a good performing amp which is 1) portable 2) tubed 3) for sensitive IEMs, $700 is a fair price.




You forgot to add, "IMO".


----------



## Subhakar

gwompki said:


> I think the b4 is pretty good bang for your buck but I have also seen this one
> 
> http://www.thetubestore.com/Parts-Accessories/Amps-and-Amp-Kits/Hybrid-Valve-Headphone-Amp
> 
> ...







harpo1 said:


> @Brooko
> Reviewed those.
> 
> Edit:  Here's a link to his review.
> http://www.head-fi.org/products/ims-hybrid-valve-headphone-amplifier-hva/reviews/15617




Thanks. Look great. Reading up more...


----------



## penmarker

subhakar said:


> You forgot to add, "IMO".


 
 I'm not sure if you've heard of this company, its called Govibe and they have a portable tubed DAC/amp unit called Govibe Porta Tube.
 Not known anymore nowadays but a few years ago they were quite favored upon. Don't know if Jaben still carrying them.


----------



## golov17

penmarker said:


> I'm not sure if you've heard of this company, its called Govibe and they have a portable tubed DAC/amp unit called Govibe Porta Tube.
> Not known anymore nowadays but a few years ago they were quite favored upon. Don't know if Jaben still carrying them.


 http://www.jaben.com.au/collections/go-vibe/products/gov-portatube


----------



## Subhakar

Thanks.


----------



## Brooko

The PortaTube was an incredible sounding tube amp - more transportable than truly portable though, and had quite a bit of heat.  Definitely one of those amps which I still regret selling though.  If I found one at a reasonable price - I'd probably buy it again.
  
 I should be getting one of Martin's new hybrid tube amps soon - now that i know this thread is here, I'll post when I've had a chance to put it through its paces.


----------



## MIKELAP

brooko said:


> The PortaTube was an incredible sounding tube amp - more transportable than truly portable though, and had quite a bit of heat.  Definitely one of those amps which I still regret selling though.  If I found one at a reasonable price - I'd probably buy it again.
> 
> I should be getting one of Martin's new hybrid tube amps soon - now that i know this thread is here, I'll post when I've had a chance to put it through its paces.


 
 Great been waiting for this upgraded model .Thanks


----------



## Criss969

I just got my B4 yesterday and decided to dismantle it to see the inside this evening. I played with the trim thingies (4 of them) and now cannot get the sound "centered". Anyone know what each knob does exactly?


----------



## penmarker

criss969 said:


> I just got my B4 yesterday and decided to dismantle it to see the inside this evening. I played with the trim thingies (4 of them) and now cannot get the sound "centered". Anyone know what each knob does exactly?


 
 You'll need the schematics for that.
  
 Also don't play with trim pots. If they're for gain settings you can very easily fry the electronics. Desktop amps can fry their transformers and output transformers. Its chaos.


----------



## gwompki

penmarker said:


> You'll need the schematics for that.
> 
> Also don't play with trim pots. If they're for gain settings you can very easily fry the electronics. Desktop amps can fry their transformers and output transformers. Its chaos.




I played with the trimpots in mine for fun but had no problem getting them back to normal as I took a photo of settings prior to adjustments. Luckily the tubes in this circuit are only used as a buffer (I believe) as adjusting the pots made very little change to actual volume. I think the chance of frying other components is minimal, but I could be mistaken.

My recommendation would be to set all of them to about 8 o'clock (just barely on) and then make small adjustments from there. The two on the right are for the right channel and two on the left are for the left. To my ears, the pot closest to the op amp, made a much more audible difference when adjusted. Start with those and then dial in with the two closer to the tube pins.


----------



## Criss969

> My recommendation would be to set all of them to about 8 o'clock (just barely on) and then make small adjustments from there. The two on the right are for the right channel and two on the left are for the left. To my ears, the pot closest to the op amp, made a much more audible difference when adjusted. Start with those and then dial in with the two closer to the tube pins.


 
 Thanks! This saved me. I tend to always make beginner mistakes when messing with things, unfortunately.


----------



## gwompki

criss969 said:


> Thanks! This saved me. I tend to always make beginner mistakes when messing with things, unfortunately.




No worries! I personally think that is the best way to learn with diy. My only recommendation would be to take good notes or photos before you start experimenting so you can put it back if need be.


----------



## gwompki

I wrote a review of the Burson V5i opamp here http://www.head-fi.org/products/burson-audio-supreme-sound-opamp-v5i/reviews/17329

All of my listening tests were done using the B4 if anyone is interested.


----------



## golov17

gwompki said:


> I wrote a review of the Burson V5i opamp here http://www.head-fi.org/products/burson-audio-supreme-sound-opamp-v5i/reviews/17329
> 
> All of my listening tests were done using the B4 if anyone is interested.


Nice review, thank, btw, where to buy orginal MUSES?


----------



## MIKELAP

gwompki said:


> I wrote a review of the Burson V5i opamp here http://www.head-fi.org/products/burson-audio-supreme-sound-opamp-v5i/reviews/17329
> 
> All of my listening tests were done using the B4 if anyone is interested.


 
 Nice review ,so the v5i helps the B4 alot then makes the B4 more tempting?


----------



## gwompki

golov17 said:


> Nice review, thank, btw, where to buy orginal MUSES?




Safest place is from a reputable electronics supplier such as Mouser

http://www.mouser.com/Search/m_ProductDetail.aspx?NJR%2FMUSES02%2F&qs=lTIKtKbByhhPORZIYvXQtw%3D%3D


----------



## gwompki

mikelap said:


> Nice review ,so the v5i helps the B4 alot then makes the B4 more tempting?




I personally think so. I'm sure a lot will depend on your source and headphones though. The Zen 2.0 which I would say is a fairly neutral, but incredible sounding earbud, benefited hugely from the V5i. Other, less resolving earbuds that I have, did not benefit as much from the upgrade. Definitely a noticeable difference over the stock NE5532, but maybe not as much as with the Zen 2.0

As I mentioned in the review, prior to hearing one, I had a hard time justifying the price of the V5i (I got my MUSES used for half Price). Now after hearing it, I would have no problem paying full price for one.


----------



## T.R.A.N.C.E.

Check out this portable tube amp, it's packed with capacitors, and what looks like a switching psu or something: https://world.taobao.com/item/542296245934.htm


----------



## golov17

t.r.a.n.c.e. said:


> Check out this portable tube amp, it's packed with capacitors, and what looks like a switching psu or something: https://world.taobao.com/item/542296245934.htm


interesting..


----------



## gwompki

I am impressed at how well the B4 can drive the HD650.  Did not expect that to be the case at all, but with the V5i opamp installed the sound is pretty spectacular to my ears.


----------



## golov17

gwompki said:


> I am impressed at how well the B4 can drive the HD650.  Did not expect that to be the case at all, but with the V5i opamp installed the sound is pretty spectacular to my ears.


where to buy V5i dual?


----------



## gwompki

Good question.  The only place I know for sure is Ebay.


----------



## Brumas7

I got my V5i recently directly ordered from the Burson audio website. The shipping cost was a bit steep though.


----------



## White Lotus

Looks like there is a 2017 model of the B5. Anyone had a listen yet?


----------



## Born2Cuddle

Has anyone tried the B4 out with a pair of Hifiman 400i headphones? I currently use them with a Fiio X3  and an O2 amp and was wondering if the Little Bear would be better/different.


----------



## TwoPalms

white lotus said:


> Looks like there is a 2017 model of the B5. Anyone had a listen yet?
> 
> 
> This one?


----------



## White Lotus

twopalms said:


> white lotus said:
> 
> 
> > Looks like there is a 2017 model of the B5. Anyone had a listen yet?
> ...


----------



## Dickymint

Hi folks, I just bought myself the B4, it hasn't had enough time yet to get the tube burnt in properly but so far I am impressed. The sound is detailed at the top end and the bass is crystal clear, I have been trying to compare it to my OPPO HA2 and sorry but so far I prefer the B4. Previously I had a B1 but it crackled and popped so much, though the sound was wonderful, hence the reason I bought the B4. When I have had a good time to try this I will let you know any further developments. By the way, is the V5i really that good an improvement? It's expensive enough!


----------



## Aradea

twopalms said:


> white lotus said:
> 
> 
> > Looks like there is a 2017 model of the B5. Anyone had a listen yet?
> ...


----------



## Dickymint

Hi folks, been using the amp for a week or so now and I do like it lots but I have an issue wherein it distorts quite badly on the bass. I suspect that it is caused by being overdriven by my Shanling M2, there is no way of adjusting the output and I have a suspicion that it is just too high a signal. But when I use my Ibasso DX50, I have the option to reduce the output level and it doesn't distort then. From other recommendations, I have ordered another amp chip, just waiting for it to arrive and I can have yet another play. As for battery life, I seen somewhere that it had a 5 hour life? So far I have only charged it once, have used it every evening to listen for at least 30mins and it is still going strong, I must have about 10 hours out of it so far! Anyway, will keep you posted.
 Oh and, it does not get hot at all, brilliant, unlike the first version!


----------



## jj69

Anyone have the B5 yet? Would love someone to compare direct with B4. Just a bit disappointed B5 appears to have the opamp soldered in place.


----------



## Dickymint

Been using the B4 for a few weeks now and I have found a few things out. Firstly, I bought a new opamp and fitted it only to have quite an imbalance between the channels, sounded good mind you but off to one side. Then I discovered I had bought it for a different job, so swapped back to the original and then balance is back. While comparing between the B4 and my Oppo HA-2, I find the B4 a bit lacking in top end detail, just rolls off too soon but otherwise a nice emotional sounding device. I have used it with my RockJaw Kommand IEMs and I can only just get past the volume pot imbalance before it begins to get too loud but if I use my Beyerdynamic 990 600 ohm headphones I can wind it up to just over 50% and it sounds super, with plenty left in the tank. The battery has had to be charged for the third time now, this time it lasted about 8 hours, so no problem for me. More to try when I get a chance, ttfn.


----------



## jj69

Just received my B5. So far, it's doing an excellent job of adding a staggering amount of background hiss to anything played through it (including silence). I knew there would be some microphonics from the tubes, but it's literally every time you so much as breathe on it. 

Am I doing something wrong or is my unit maybe defective?


----------



## silverfishla

Anybody here roll the op amp in the B4? Which ones sound good in it?


----------



## jj69

Just to follow up on my B5, seller said it must be defective and is sending out a replacement now. Wonder if B5 quality control is bad in general? 




jj69 said:


> Just received my B5. So far, it's doing an excellent job of adding a staggering amount of background hiss to anything played through it (including silence). I knew there would be some microphonics from the tubes, but it's literally every time you so much as breathe on it.
> 
> Am I doing something wrong or is my unit maybe defective?


----------



## silverfishla

I decided to get the B4 and I think it is quite good.  I put a Burson V5i in there and it sounds pretty great.  Makes my Aune M1s sound better single ended than using the Aune balanced out.  More separation, bass, and clarity.  I have also used it with a Zishan Z1 and have had great results.  Both DAPs sound noticeably better with the Amp, both in power and sound quality.  I love it.


----------



## Yobster69

silverfishla said:


> I decided to get the B4 and I think it is quite good.  I put a Burson V5i in there and it sounds pretty great.  Makes my Aune M1s sound better single ended than using the Aune balanced out.  More separation, bass, and clarity.  I have also used it with a Zishan Z1 and have had great results.  Both DAPs sound noticeably better with the Amp, both in power and sound quality.  I love it.


Hi. Thanks for posting and letting us know. I've also been enjoying the B4, it's actually much better than I thought it would be. Can I  trouble you to briefly divulge how the V5i changed the sound from the original, and how much you paid for the opamp? Thanks in advance.


----------



## silverfishla

Yobster69 said:


> Hi. Thanks for posting and letting us know. I've also been enjoying the B4, it's actually much better than I thought it would be. Can I  trouble you to briefly divulge how the V5i changed the sound from the original, and how much you paid for the opamp? Thanks in advance.


I think I paid something like $65 total for the Op-amp with shipping from Australia.  I bought it straight from the Burson website.  I too, was suprised that this amp sounded as good as it does.  The original op-amp sounds good as do others in the B4.  The Burson though, is quite different in that it makes vocals very sweet sounding and has great separation and is very full sounding.  It is quite silent and is less "rough" sounding that the BB op-amps.  I have also tried the Muse02 in the amp and it also sounds very good, but is more focused on the mids (and mid-bass) than the Burson.  This can be a great thing, but for me, in this amp, clogs up the middle a bit.  I think the Burson is a better compliment with the "tubish" sound of the B4.  Warm but clear and good bottom end.


----------



## golov17

My v5i on the way, i will try it vs muses02 too


----------



## silverfishla

golov17 said:


> My v5i on the way, i will try it vs muses02 too


Ahh, you'll like those.  You like earbuds and the Mojito sounds great with this amp.  Just remember to optimize the trim pots inside when you change around the Op-amps, makes the difference.


----------



## Yobster69

silverfishla said:


> I think I paid something like $65 total for the Op-amp with shipping from Australia.  I bought it straight from the Burson website.  I too, was suprised that this amp sounded as good as it does.  The original op-amp sounds good as do others in the B4.  The Burson though, is quite different in that it makes vocals very sweet sounding and has great separation and is very full sounding.  It is quite silent and is less "rough" sounding that the BB op-amps.  I have also tried the Muse02 in the amp and it also sounds very good, but is more focused on the mids (and mid-bass) than the Burson.  This can be a great thing, but for me, in this amp, clogs up the middle a bit.  I think the Burson is a better compliment with the "tubish" sound of the B4.  Warm but clear and good bottom end.


Fantastic, thank you. Looks like I'll be on the Burson site later on today then. 
Sorry, one more question if you don't mind. Did altering the trim pots with the original opamps change the sound much? For the better? 
Cheers


----------



## silverfishla

Yobster69 said:


> Fantastic, thank you. Looks like I'll be on the Burson site later on today then.
> Sorry, one more question if you don't mind. Did altering the trim pots with the original opamps change the sound much? For the better?
> Cheers


Well, I think the goal, is to get the tubes to flood in as much as you can without creating distortion.  Each Op-amp is a little tiny bit different.  The more you "lessen" the trim pots (counter clockwise) the colder the sound.  The more you open them up, the warmer and more open they sound (tubes...voltage..not sure).  You can do it with your earphones on and with the unit on with a tiny screwdriver.  Tune it by ear.  You'll be able to hear when it starts to distort, then dial it back.  If you are at a point of balance now, make a note of where your trims are at then incrementally increase each pot the same amount.  If you get out of balance, you'll hear it.  You may be out of balance to begin with since I don't know how well they tune these from the factory.  Again, you'll have to trust your ears.  And when I say incrementally, I mean like an 1/8 - 1/4 turn of the trim pots.  Adjusting these does make a big difference.  From the factory, mine were turned down about a 1/4 on the low side.  My guess would be it's on purpose so as to not get any complaints of distortion or extraneous noise.


----------



## Yobster69

silverfishla said:


> Well, I think the goal, is to get the tubes to flood in as much as you can without creating distortion.  Each Op-amp is a little tiny bit different.  The more you "lessen" the trim pots (counter clockwise) the colder the sound.  The more you open them up, the warmer and more open they sound (tubes...voltage..not sure).  You can do it with your earphones on and with the unit on with a tiny screwdriver.  Tune it by ear.  You'll be able to hear when it starts to distort, then dial it back.  If you are at a point of balance now, make a note of where your trims are at then incrementally increase each pot the same amount.  If you get out of balance, you'll hear it.  You may be out of balance to begin with since I don't know how well they tune these from the factory.  Again, you'll have to trust your ears.  And when I say incrementally, I mean like an 1/8 - 1/4 turn of the trim pots.  Adjusting these does make a big difference.  From the factory, mine were turned down about a 1/4 on the low side.  My guess would be it's on purpose so as to not get any complaints of distortion or extraneous noise.


Very consice and excellent info, thank you. This is my first 'dip' into the tube sound and I was a little apprehensive of changing anything, but now you have explained how to alter these I'll be straight on it as soon as I get in from work. 
I'll report back how I get on


----------



## silverfishla

@golov17 Hey would you mind letting me know what earbuds you think sound good with the B4 and your setup?  Right now, I actually think that the Toneking TP16 sounds best above even my more expensive buds (I actually like it better than Mojito, even though I like that one too).  I know you've got a lot of buds and give me some good thoughtful suggestions.


----------



## golov17

[QUOTE = "silverfishla, сообщение: 13496337, член: 460493"] [USER = 404367] @ golov17 [/ USER] Эй, вы не могли бы дать мне знать, что вы думаете Earbuds звук хороший с В4 и вашей установки? Прямо сейчас, я на самом деле думаю, что Toneking TP16 звучит лучше даже выше моих более дорогих почек (я на самом деле, как это лучше, чем Mojito, хотя мне нравится, что один тоже). Я знаю, что у вас есть много бутонов и дать мне некоторые хорошие вдумчивые предложения. [/ QUOTE]
Роза Мася, Ubiquo es903, В. Е. Asura, Boarseman mx98, etc.. With bright mids and more detailed sounds, than Zen2.0, K's300, Dunu etc..


----------



## cfbruck

silverfishla said:


> I think I paid something like $65 total for the Op-amp with shipping from Australia.  I bought it straight from the Burson website.  I too, was suprised that this amp sounded as good as it does.  The original op-amp sounds good as do others in the B4.  The Burson though, is quite different in that it makes vocals very sweet sounding and has great separation and is very full sounding.  It is quite silent and is less "rough" sounding that the BB op-amps.  I have also tried the Muse02 in the amp and it also sounds very good, but is more focused on the mids (and mid-bass) than the Burson.  This can be a great thing, but for me, in this amp, clogs up the middle a bit.  I think the Burson is a better compliment with the "tubish" sound of the B4.  Warm but clear and good bottom end.



Hi, could I ask which Burson Opamp you are using. I'm new to this so its a bit confusing.

Is it the V5i Dual SS?

And do I understand it correctly that I only need one of those, and I replace the chip that is visible through the screen?


----------



## golov17 (May 30, 2017)

cfbruck said:


> Hi, could I ask which Burson Opamp you are using. I'm new to this so its a bit confusing.





cfbruck said:


> Is it the V5i Dual SS?
> 
> And do I understand it correctly that I only need one of those, and I replace the chip that is visible through the screen?


I got my v5i dual, its sounds amazing with b3 and 400 Ohms earbuds


----------



## silverfishla

cfbruck said:


> Hi, could I ask which Burson Opamp you are using. I'm new to this so its a bit confusing.
> 
> Is it the V5i Dual SS?
> 
> And do I understand it correctly that I only need one of those, and I replace the chip that is visible through the screen?


Yes, the V5i dual is the one to get.


golov17 said:


> I got my v5i dual, its sounds amazing with b3 and 400 Ohms earbuds


I knew you would love it!  How could you not, right?


----------



## golov17

silverfishla said:


> Yes, the V5i dual is the one to get.
> 
> I knew you would love it!  How could you not, right?


Yeah


----------



## golov17

Waiting Walnut v2s for testing with Burson OPA too ))


----------



## silverfishla

golov17 said:


> Waiting Walnut v2s for testing with Burson OPA too ))


I have a V2s coming too and am curious to hear the Burson in it.  I just bought one of these http://www.ebay.com/itm/Dual-Discre...456047?hash=item20efc284af:g:EqYAAOSwCZ5Vfdzn one late night in a bit of an impulse buy.  I'm not sure if it's going to fit or work in the B4 or Zishan or Walnut.  It got some great reviews and one even said better than the Burson.  We'll see because it's doing some things that a regular op-amp isn't.  It'll be a mystery, hopefully a good one.


----------



## golov17

Выглядит круто..


----------



## silverfishla

golov17 said:


> Выглядит круто


What does that mean?


----------



## golov17

silverfishla said:


> What does that mean?


A lot discrete elements


----------



## jamonbread

I recently ordered the Little Bear B4 for use with my Agptek/Benjie S5 and it will be my first headphone amp. I was mainly interested in the B4 because of the tubes and the option of using higher ohm cans. 

What volume level do you guys set your DAP's at when using with the B4? I mostly set my S5's volume level between 3/5 depending on the music I'm playing. I know with digital output its better to max out the audio output to maintain bitrates and dynamic range, but I'm not sure the same applies to analogue signals as well?


----------



## choisan

i am using the b4+ single tube with my onkyo dpx1, i can tell you that i just turned the volume about 1/10. it is already loud and clear. 
i changed to use the LME49720, the sound quality was instantly better. and i will be testing the Burson V5i Dual soon.


----------



## jamonbread

choisan said:


> i am using the b4+ single tube with my onkyo dpx1, i can tell you that i just turned the volume about 1/10. it is already loud and clear.
> i changed to use the LME49720, the sound quality was instantly better. and i will be testing the Burson V5i Dual soon.



You set the volume of your onkyo 1/10?  I purchased a OPA2604AP to try out with the B4 as it was pretty cheap, but I was recently looking at discrete op amps and I came across Burson V5i . I've never really messed around with 
op amps before but if I can hear an improvement or change in sound quality I might eventually consider something discrete like the V5i.


----------



## choisan

No, i set my onkyo to line out. On my B4, i only turned to 1/10 of volume.
For the first impression, yes, you can tell the improvement. More level of detail and the sound quality is much clear.

I will brun in more and update later on.


----------



## jamonbread

choisan said:


> No, i set my onkyo to line out. On my B4, i only turned to 1/10 of volume.
> For the first impression, yes, you can tell the improvement. More level of detail and the sound quality is much clear.
> 
> I will brun in more and update later on.



I just got my B4 this morning it sounds great and having more subtle control over the volume as apposed to digital volume is great. The tubes do seem to be adding something noticeably warm to the sound, I can detect very subtle background hiss when nothing at all is playing but the microphonics aren't as bad as a was expecting reading some comments.  Well worth the extra pocket bulk for me.


----------



## choisan

You probably get a dual tubes version of Little Bear. Friend of mine who has it said the amp does required 1, 2 hours of warm up so as to have the performance. But once it is warm up, the sound is very nice.
Mine is single tube, the reason i bought this is that it doesn't take long to warm up. Just few mins.


----------



## choisan

i am planning to change the cap inside as well. someone suggested to change and use some solid state, which cost very little but performance is noticeable


----------



## jamonbread

choisan said:


> i am planning to change the cap inside as well. someone suggested to change and use some solid state, which cost very little but performance is noticeable



Yeah I got the 2 tube version and there's no charging indicator on the device its just the plug has one. I though it might have some LED's on the device but it doesn't. Its warms up pretty quickly.


----------



## choisan

Mine is having red light around the plug area when it is charging. It will turn blue upon fully charged.


----------



## jamonbread

choisan said:


> Mine is having red light around the plug area when it is charging. It will turn blue upon fully charged.



I'm really happy with it overall, my only one concern is the headphone jacks seem a bit cheap and will likely suffer connection issues down the line. I really need to learn how to solder so I can at least replace the tubes when the finally crap out.


----------



## jamonbread

choisan said:


> Mine is having red light around the plug area when it is charging. It will turn blue upon fully charged.



Well unfortunately mines developed a random static sound in the left channel, tapping the device sometimes makes it go away and sometimes its not there at all? Bit disappointed as I can't work out whats coursing it,  and I can't apply contact cleaner to the volume pot to rule that out as there's no way to get it inside the pot itself.


----------



## silverfishla (Aug 25, 2017)

jamonbread said:


> Well unfortunately mines developed a random static sound in the left channel, tapping the device sometimes makes it go away and sometimes its not there at all? Bit disappointed as I can't work out whats coursing it,  and I can't apply contact cleaner to the volume pot to rule that out as there's no way to get it inside the pot itself.


What are you using as a source for it?  It will pick up RF noise from a phone or if you are near a computer.  Static, basically.  Sometimes, it's absolutely clean sounding, but sometimes it will pick up some static noise.  I usually can't hear it while the music is playing and doesn't affect my enjoyment of the amp.  On another note, I changed out the capacitors on the amp and some of that noise was greatly reduced by doing that.  Now I  barely hear any static, and it's only there periodically.  I think it's RF noise though, since I live near a radio tower.
This is what mine looks like at the moment.  I'm waiting for another capacitor in the mail, to see if I can fit it in so that I can put the lid back on it.  Just experimenting.   I find that this makes the Burson sound even better than the stock setup.   Really wonderful clarity and great bass.  Love it.


----------



## jamonbread (Aug 26, 2017)

silverfishla said:


> What are you using as a source for it?  It will pick up RF noise from a phone or if you are near a computer.  Static, basically.  Sometimes, it's absolutely clean sounding, but sometimes it will pick up some static noise.  I usually can't hear it while the music is playing and doesn't affect my enjoyment of the amp.  On another note, I changed out the capacitors on the amp and some of that noise was greatly reduced by doing that.  Now I  barely hear any static, and it's only there periodically.  I think it's RF noise though, since I live near a radio tower.
> This is what mine looks like at the moment.  I'm waiting for another capacitor in the mail, to see if I can fit it in so that I can put the lid back on it.  Just experimenting.   I find that this makes the Burson sound even better than the stock setup.   Really wonderful clarity and great bass.  Love it.



I was using it with my Benjie MP3 player, there'e always been a small background hiss but it doesn't amplify at all (barley noticeable 99% of the time) This crackle/pop is new with the same setup and you can hear it over any audio volume (only in the one channel), but I've finally found out what the problem is, and its the volume pot. Tapping the volume pot lightly used to make it go away, and turning the pot past a certain point (too loud) it kicks in again permanently at higher volumes. Its now basically become permanent at all volumes in the same one channel (i can reduce it a bit by sweeping the pot up and down and tapping it). It has all the hallmarks of a crackly volume pot, and I've tried getting contact cleaner into the pot from all angles put I can't get any inside the pot itself.

I managed to remove the knob and get the front off but I'm going to have to find a replacement 8pin 9mm 50k switched pot, and the same branded ALPS pots are out of stock everywhere. I also need to learn to solder my past attempts have ended in failure. I'm surprised the pot got dust inside in the first place as its a sealed unit. Same symptoms I have in the old Pioneer amp.


----------



## cathee

MIKELAP said:


>



Anyone have more information on this IMS amp? Looks very interesting, but I can't seem to find any information any where. Their website doesn't have anything either...

x


----------



## magisterarus

cathee said:


> Anyone have more information on this IMS amp? Looks very interesting, but I can't seem to find any information any where. Their website doesn't have anything either...
> 
> x



You can read a complete review by Brooko here:

https://www.head-fi.org/showcase/ims-hybrid-valve-headphone-amplifier-hva.21442/reviews


However we are slightly OT here, since it's not a tube amplifier from China, but from New Zealand.


----------



## cathee

magisterarus said:


> You can read a complete review by Brooko here:
> 
> https://www.head-fi.org/showcase/ims-hybrid-valve-headphone-amplifier-hva.21442/reviews
> 
> ...



Thank you for the quick reply. Apologies for bringing this OT, did not even realize they were from NZ!

Also, have read Brooko's write up, unfortunately as detailed and thorough as it is, a data point of one is somewhat useless. Would love to read more about it, seems like a very interesting product.


----------



## kukkurovaca

cathee said:


> Thank you for the quick reply. Apologies for bringing this OT, did not even realize they were from NZ!
> 
> Also, have read Brooko's write up, unfortunately as detailed and thorough as it is, a data point of one is somewhat useless. Would love to read more about it, seems like a very interesting product.



I think this is the thread for it: https://www.head-fi.org/threads/wor...t-smaller-than-most-cellphones.764953/page-12


----------



## Yobster69

I could be very wrong, but I do not think this IMS amp is being made anymore. Please correct me if It is though???
Link??


----------



## magisterarus

Yobster69 said:


> I could be very wrong, but I do not think this IMS amp is being made anymore. Please correct me if It is though???
> Link??



http://www.ims-nz.com/


----------



## Yobster69

magisterarus said:


> http://www.ims-nz.com/


Oh my wordy


----------



## Klaatu (Dec 30, 2017)

I just purchased a Little Bear B5 for $40.99 here: https://www.aliexpress.com/item/Dou...mplifier-Audio-HiFi-Amp-Free/32740509983.html
It's listed at $44.99 but they gave me a $4 off coupon for joining Alibaba. They're claiming delivery within 15 days.


----------



## Klaatu (Jan 19, 2018)

I got the B5 in today. It is indeed functional and it seems to be driving the daylights out of my HE-400 cans. I'm going to need some quality time with it, but so far I really dig it.


Those are definitely tiny little red LEDs behind the tubes, so they don't glow by themselves.


----------



## Klaatu (Jan 22, 2018)

jj69 said:


> Just to follow up on my B5, seller said it must be defective and is sending out a replacement now. Wonder if B5 quality control is bad in general?


I noticed that it can be noisy as all get out if it's within a foot of the phone. I may have to dig out my old iPod Classic for use with this. The one time I've taken it out of the house I used a 4ft stereo cable and kept the amp in a separate pocket on the opposite side of my body as my phone and it seemed to isolate it adequately.
The stereo jacks seem to be a little touchy; if something isn't plugged in snugly enough, the left channel will often cut out.
As far as power, it was more than adequate to drive my HE-400 cans for my liking (really loud!) and seemed to do really well on battery life. It seems to be doing well within it's limitations.


----------



## nofacemonster

I am planing on ordering a Little Bear B5 today. Do you think it is good...? because i want a portable tube amp. I love the warm mellow tube sound. I won't be using it on the go but probably i will be using it on a table top or bed in a stationary way. I don't have extremely good high end audio gear, I will be using it with my xiaomi phone and KZ ZS5.


----------



## bsoplinger

I have a little bear 4 and have a 5 swimming its way from China so I'd say that they're nice little amps. The older version 4 has a socket so you can change the opamp where the 5 has it soldered in. However I don't think you would be the type to change opamp considering your simple setup. They also aren't very portable in the stick it in your pocket and have music while going about your day sense. But again your setup is more of the occasionally move from here to there portable sense and either is fine for that.


----------



## nofacemonster

bsoplinger said:


> I have a little bear 4 and have a 5 swimming its way from China so I'd say that they're nice little amps. The older version 4 has a socket so you can change the opamp where the 5 has it soldered in. However I don't think you would be the type to change opamp considering your simple setup. They also aren't very portable in the stick it in your pocket and have music while going about your day sense. But again your setup is more of the occasionally move from here to there portable sense and either is fine for that.



Thanks a load.... i ordered the B5 because i felt that after reading all the reviews it has better battery life but less power. I don't need too much power because i will be driving cheapo headphones with it. Stuff like KZ etc. I just can't wait to couple this up with my KZ ZS1 and see how it might sound because i simply love the sound of ZS1 (very sensitive to highs).

Thank you for the recommendation.


----------



## nofacemonster

bsoplinger said:


> I have a little bear 4 and have a 5 swimming its way from China so I'd say that they're nice little amps. The older version 4 has a socket so you can change the opamp where the 5 has it soldered in. However I don't think you would be the type to change opamp considering your simple setup. They also aren't very portable in the stick it in your pocket and have music while going about your day sense. But again your setup is more of the occasionally move from here to there portable sense and either is fine for that.



About three days back i received my Little Bear B5 and i think it is a disaster. I really thought it would be better than this, maybe my unit is faulty. I ran it for about 10 to 12 hours thinking that burn in will make things better but nothing improved. Here is my experience.

B5 has a terrible HISS, i tried it with all my headphones and the HISS is there even when nothing is connected to it ( just headphones ) and the volume is set to zero. I told the place i bought it and they were telling me to change the OP amp. I don't know if it will fix this.

I connected it to my laptop and while the laptop is plugged there is lot of distortion in the sound. When i ran the laptop on battery it's just like other devices, just the hiss.

#1. KZ ZS5 ~ Complete disaster, don't even think about using this with B5. It completely cuts off the bass and it is very audible.
#2. KZ ZS1 ~ It's pretty much alright. Bass is there but not as much as i had it connected directly to source ( probably because ZS1 is super bass heavy )
#3. KZ ATR ~ Pretty good, bass is there and everything is warmer and sound has definitely improved towards more mellower, sweeter warmer tone.
#4. Panasonic RP-HTX7 ~ Not bad, warmer tone is there and bass had not being altered.
#5. Audio Technica S600 (Back band) ~ best pair or headphones i have to go with B5, sounds awesome.
#6. Philips SBC-HP200 ~ (Very old semi open back) ~ Very laid back, warmer sound, No alteration to bass.

on all of above HISS is there and on KZ-ZS5 it is very audible. I guess B5 is not good with multi driver IEM's.

If anyone knows how to get rid of this HISS, it would be wonderful.


----------



## nofacemonster

I just did the full sound test again.... in all of above headphones i tested B5 does kill bass for some extent. Is this common or something wrong with my B5


----------



## nofacemonster

jj69 said:


> Just received my B5. So far, it's doing an excellent job of adding a staggering amount of background hiss to anything played through it (including silence). I knew there would be some microphonics from the tubes, but it's literally every time you so much as breathe on it.
> 
> Am I doing something wrong or is my unit maybe defective?



I am having a similar problem. Was it a defective unit?


----------



## slinkyjynx

I got the B4 this week and man I love this little thing! Such beautiful, smooth sound for next to no investment. Battery life is good, and it improves just about every source. Anyone wanting to dig into tube sound on a budget can't go wrong with this.


----------



## bsoplinger

You might want to consider doubling the cost of your B4 and add the Burson V5i opamp to it. I'm playing around with a review sample I received, primarily to stick in an Xduoo XD-05 but I installed it in my little bear tube amp b4 also. Really nice combination. You get that warmish tube sound and the improved imaging of the opamp although I feel that it does sound nicer in the XD-05. Once I get my review finished up I plan to purchase another one for my b4.


----------



## slinkyjynx

bsoplinger said:


> You might want to consider doubling the cost of your B4 and add the Burson V5i opamp to it. I'm playing around with a review sample I received, primarily to stick in an Xduoo XD-05 but I installed it in my little bear tube amp b4 also. Really nice combination. You get that warmish tube sound and the improved imaging of the opamp although I feel that it does sound nicer in the XD-05. Once I get my review finished up I plan to purchase another one for my b4.


Assuming I know nothing, how difficult is it to replace?


----------



## bsoplinger

You need an appropriate sized torx screwdriver. I want to say T6 but it might be a T5, I think the correct size is in this thread and if not I can make sure to get the correct one. Then 4 screws on the corners of the front panel, the one with the knob. You carefully slide the panel, attached circuit board and battery out by about 2 inches. The most difficult thing will be prying out the existing opamp if you don't have a DIP removal tool. Careful, slow, gentle prying with a small flat blade screwdriver works fine. You then must orient the new chip properly. There's a semi circular depression on the DIP8 socket and on the opamp (new Burson or old stock one) that you align in the same direction. Push firmly and gently to seat the opamp. Then you push the battery, board and front panel back into place and replace the screws. Probably take you 10 minutes, 8 of which are just you being extrda cautious because you haven't done anything like that before.

Honestly if you know what you're doing and have the correct torx screwdriver handy it really is literally a 2 or 3 minute operation.

I'm pretty sure there are even pictures and a description of exactly what to do here on head-fi. If not this thread then the Xduoo XD-05 thread. Topology wise the cases and board, battery and where to place the opamp are very similar so instructions for one will be good enough to do the other. Last place to look is the Burson V5i review thread. The directions are somewhere here.


----------



## slinkyjynx

bsoplinger said:


> You need an appropriate sized torx screwdriver. I want to say T6 but it might be a T5, I think the correct size is in this thread and if not I can make sure to get the correct one. Then 4 screws on the corners of the front panel, the one with the knob. You carefully slide the panel, attached circuit board and battery out by about 2 inches. The most difficult thing will be prying out the existing opamp if you don't have a DIP removal tool. Careful, slow, gentle prying with a small flat blade screwdriver works fine. You then must orient the new chip properly. There's a semi circular depression on the DIP8 socket and on the opamp (new Burson or old stock one) that you align in the same direction. Push firmly and gently to seat the opamp. Then you push the battery, board and front panel back into place and replace the screws. Probably take you 10 minutes, 8 of which are just you being extrda cautious because you haven't done anything like that before.
> 
> Honestly if you know what you're doing and have the correct torx screwdriver handy it really is literally a 2 or 3 minute operation.
> 
> I'm pretty sure there are even pictures and a description of exactly what to do here on head-fi. If not this thread then the Xduoo XD-05 thread. Topology wise the cases and board, battery and where to place the opamp are very similar so instructions for one will be good enough to do the other. Last place to look is the Burson V5i review thread. The directions are somewhere here.


Firstly, thanks for such a detailed reply. I think it's doable 

What sort of improvements could I expect? Just thinking, it looks like such a small chip, I couldn't imagine it would have a large impact - but please excuse my ignorance.


----------



## bsoplinger

slinkyjynx said:


> Firstly, thanks for such a detailed reply. I think it's doable
> 
> What sort of improvements could I expect? Just thinking, it looks like such a small chip, I couldn't imagine it would have a large impact - but please excuse my ignorance.


LOL, I was thinking as I wrote it that there wasn't that much detail but honestly there really isn't anything to doing this.

I've seen the change to the sound for the Burson V5i as holographic and I think that's a reasonable attempt to describe the change in sound. Bass is tighter, more controlled. Some of the music I listen to has alternate percussion, things like hand drums, and you really can hear the human element in it with the V5i. You can hear the slide of a palm across the surface to change the pitch or duration of a strike. The striking of the body of the instrument to create a thunk. You can hear the same type of thing with an acoustic guitar player striking the body of the guitar. There's just a bit of extra definition to these sounds that makes them sound so much more present. Higher up in the vocal and mid range groups of instruments like in a classical work just seem to be just a bit more distinct, the layers just a bit more separate. The human voice stands out just a bit more. 

Its a bit difficult to describe but easy to hear.


----------



## slinkyjynx

bsoplinger said:


> LOL, I was thinking as I wrote it that there wasn't that much detail but honestly there really isn't anything to doing this.
> 
> I've seen the change to the sound for the Burson V5i as holographic and I think that's a reasonable attempt to describe the change in sound. Bass is tighter, more controlled. Some of the music I listen to has alternate percussion, things like hand drums, and you really can hear the human element in it with the V5i. You can hear the slide of a palm across the surface to change the pitch or duration of a strike. The striking of the body of the instrument to create a thunk. You can hear the same type of thing with an acoustic guitar player striking the body of the guitar. There's just a bit of extra definition to these sounds that makes them sound so much more present. Higher up in the vocal and mid range groups of instruments like in a classical work just seem to be just a bit more distinct, the layers just a bit more separate. The human voice stands out just a bit more.
> 
> Its a bit difficult to describe but easy to hear.


Ordered myself the Burson V5i - everywhere seems to really regard it quite well. Also looking at replacing the battery in the unit, it doesnt seem to use a particulary efficient design so I can swap it for a much larger capacity to get more playing time.


----------



## slinkyjynx

Aaand, the V5i is in. For anyone considering it, just do it. The difference is insane, super easy to fit too. Just be careful not to hit the tubes when you’re prying out the chip.


----------



## frogmeat69

I have a V5i in my LD 1+, might have to swap it out and give it a try.  
And get yourself a pair of these to pull the chips, https://www.ebay.com/itm/Board-Pull...483314?hash=item239b6d3eb2:g:0NUAAOSwB9danCNU
94 cents, shipped free, might take 3 months to swim here though.


----------



## bsoplinger

slinkyjynx said:


> … Aaand, the V5i is in. For anyone considering it, just do it. The difference is insane, super easy to fit too. Just be careful not to hit the tubes when you’re prying out the chip.


Glad to hear that you decided to give it a try. It really is simple to do and sounds much better than what is in there. Hopefully I'll have my amp review up tomorrow with pictures for anyone else worried like you were about swapping the opamp. I decided to add a how to install it section with a spoiler to keep it out of the review itself yet there for those concerned about the difficulty or risk of doing a swap.


----------



## Sylaw (May 3, 2018)

--


----------



## Sylaw

bsoplinger said:


> Glad to hear that you decided to give it a try. It really is simple to do and sounds much better than what is in there. Hopefully I'll have my amp review up tomorrow with pictures for anyone else worried like you were about swapping the opamp. I decided to add a how to install it section with a spoiler to keep it out of the review itself yet there for those concerned about the difficulty or risk of doing a swap.




hi im new to this tube amp thing.. so i ordered my B4 today.. but im intending to pair it up with my sony XZP. i knw i will have some Electronic interference, but is there a way to eliminate it? ( Ex- having a foil barrier between the phone and the amp? XD i knw i sound pretty stupid here )


----------



## slinkyjynx

Sylaw said:


> hi im new to this tube amp thing.. so i ordered my B4 today.. but im intending to pair it up with my sony XZP. i knw i will have some Electronic interference, but is there a way to eliminate it? ( Ex- having a foil barrier between the phone and the amp? XD i knw i sound pretty stupid here )


Yeah, put your phone on airplane mode and all interference disappears. Foil doesn't really do anything, distance helps but emphasis on 'helps' as it doesn't eliminate the noise. I upgraded the cable to a shielded one and that helped a bit as well. Best bet is to turn on airplane mode, then you will have no interference.


----------



## rafaelo

I just got yesterday my little bear B4 from Amazon after watching the raving z reviews but I noticed that the tubes are different from his review.

I expected Raytheon but I have Jan 5899. Are these tubes the same brand and if not how they compare with the original Raytheon?

How easy is to change rubes with this unit? I am afraid my DIY skills are not good enough for tube rolling for this amp.

I have other preamplifier from this company where is very easy to roll rubes. I got some amazing NoS british tubes I changed the power supply to an ifi ipower one and the result is wonderful.

But I am dissapointed not having Raytheon on this and before i commit in  opamp rolling I need some advice from you.

Really appreciated and many thanks in advance.


----------



## slinkyjynx

rafaelo said:


> I just got yesterday my little bear B4 from Amazon after watching the raving z reviews but I noticed that the tubes are different from his review.
> 
> I expected Raytheon but I have Jan 5899. Are these tubes the same brand and if not how they compare with the original Raytheon?
> 
> ...


Did you perhaps even try googling 'JAN 5899' before asking on here?


----------



## rafaelo

slinkyjynx said:


> Did you perhaps even try googling 'JAN 5899' before asking on here?


Ok apologies then. I quickly Googled 5988 or something else and could not find any information. I searched Watford valves store which is where I am shoping valves and could not find replacement for these valves. I am much happier now.


I can refrase my questions then: is easy to roll valves or replace valves here and do you need any specific tool to do it? What guys you suggest for an upgrade?

In addition, Is the V5i the best upgrade possible or are they any other better options out there?


----------



## slinkyjynx

rafaelo said:


> Ok apologies then. I quickly Googled 5988 or something else and could not find any information. I searched Watford valves store which is where I am shoping valves and could not find replacement for these valves. I am much happier now.
> 
> 
> I can refrase my questions then: is easy to roll valves or replace valves here and do you need any specific tool to do it? What guys you suggest for an upgrade?
> ...


Easy enough, all you need are the usual tools for soldering small circuits - as for recommendations, I'd suggest staying away from the tubes (they're good) and focusing on replacing the OP with a V5i, which is a fantastic upgrade. You could replace it with a V6 by cutting out the perspex front window to enable it to fit. This should sound better, but you'd lose the form factor, so it's up to you. I'd recommend the V5i whole-heartedly though.


----------



## rafaelo

slinkyjynx said:


> Easy enough, all you need are the usual tools for soldering small circuits - as for recommendations, I'd suggest staying away from the tubes (they're good) and focusing on replacing the OP with a V5i, which is a fantastic upgrade. You could replace it with a V6 by cutting out the perspex front window to enable it to fit. This should sound better, but you'd lose the form factor, so it's up to you. I'd recommend the V5i whole-heartedly though.


So many thanks mate. These American tubes are way to good for me then and the v6 upgrade is way above my skills, tools and determination.

I will do the V5i then. One other thing I noticed is that when I touched the connection in my headphones the music stops for a second. Is that bad unit or normal with this unit?

In any case, I will test my unit for a while and if everything good I am doing the V5i upgrade, this upgrade I believe I can manage .


----------



## slinkyjynx

rafaelo said:


> So many thanks mate. These American tubes are way to good for me then and the v6 upgrade is way above my skills, tools and determination.
> 
> I will do the V5i then. One other thing I noticed is that when I touched the connection in my headphones the music stops for a second. Is that bad unit or normal with this unit?
> 
> In any case, I will test my unit for a while and if everything good I am doing the V5i upgrade, this upgrade I believe I can manage .


Music should not stop at all. One thing that isnt clear with the little bear is when you plug your headphone and input in, you need to push quite firmly to get a 'click' for the full connection, then its rock solid. Try pushing it in a bit more so you get the click, and then it shouldn't cut out.


----------



## jamonbread

Does anyone know what the 4 adjustments are for on the little bear B4, do any of them adjust the gain for using lower ohm cans?


----------



## frogmeat69

rafaelo said:


> I just got yesterday my little bear B4 from Amazon after watching the raving z reviews but I noticed that the tubes are different from his review.
> 
> I expected Raytheon but I have Jan 5899. Are these tubes the same brand and if not how they compare with the original Raytheon?
> 
> ...


The JAN stands for Joint Army Navy, they were made for  Military use. I have the same, and for such a tiny lil amp it sounds pretty awesome. 
I have yet to do any op amp rolling, but have about 12 to try.


----------



## rafaelo

First time out of the box played for an hour, needed charging after that, that is fine. 

I fully charged, or I thought did, it played for 15-20 dead. Ok I thought I did not manage to charge first time. Second time I tried to charge completely, it played only 10 minutes. 

I am thinking obviously to use a different charger, a 12 V I have from a different preamplifier but is this really a problem in charger, a battery problwm or something else is wrong with my unit? 

Any advice will be much appreciated.


----------



## slinkyjynx

rafaelo said:


> First time out of the box played for an hour, needed charging after that, that is fine.
> 
> I fully charged, or I thought did, it played for 15-20 dead. Ok I thought I did not manage to charge first time. Second time I tried to charge completely, it played only 10 minutes.
> 
> ...


Sounds like an issue, I routinely get around 4 hours at max volume per charge. Just make sure the unit is OFF when you charge it, otherwise you barely get any charge at all from it. Charging time is usually around the 2 hour mark to get to green light, but I've noticed if you jiggle the connection it flicks red at some angles, so be sure yours is connected properly.

You can tell this was cheap, right?


----------



## Yobster69

rafaelo said:


> First time out of the box played for an hour, needed charging after that, that is fine.
> 
> I fully charged, or I thought did, it played for 15-20 dead. Ok I thought I did not manage to charge first time. Second time I tried to charge completely, it played only 10 minutes.
> 
> ...


I wouldn’t suggest charging this from anything else. As far as I am aware the cut off circuit to which the info is relayed from the battery once fully done is in the plug unit rather than in the amp. It could mean the battery gets ‘overcharged’ and I am not sure what implications this would have! It could be very bad, and a lot of heat and maybe worse happening. 
I could be wrong of course, I’m certainly no electronics wizard, but I wouldn’t want to find out......


----------



## rafaelo (May 16, 2018)

slinkyjynx said:


> Sounds like an issue, I routinely get around 4 hours at max volume per charge. Just make sure the unit is OFF when you charge it, otherwise you barely get any charge at all from it. Charging time is usually around the 2 hour mark to get to green light, but I've noticed if you jiggle the connection it flicks red at some angles, so be sure yours is connected properly.
> 
> You can tell this was cheap, right?


The green red light alternates all time with the slightest touch. First time I saw red after charging some time so I thought it did not charge. Second time I made sure that will be green all the time but I now read the instructions it says charge until red becomes green. I will try now to do that use a 12V charger instead the 12.6V included and change the small adaptor that connects to the power.

You were very right about the headphones needed to inserted fully into the jack and this was resolved. However the other jack when is touched make noise maybe is the small cable 3.5 to 3.5 which seems surprisingly good though.

I am worried thought that something is burned so after 10 minutes when the tubes raise fully temperature the unit makes a noise and is suddenly off. However, after charging it plays back for a while ...

I expected cheap but I expected also functional. I have their other preamplifier for a year now and plays fine no problems so far. I changed the original tubes that were unassuming and the power supply and the sound quality took off.

So preamplifier was 40£ + 30£ tubes + 50£ the ifi ipower. So the mods were double the price of the unit but they were what made the unit to take off.

This is why I take absolutely on board your recommendation for an upgrade with V5i but need to make it functional first.


----------



## rafaelo

Yobster69 said:


> I wouldn’t suggest charging this from anything else. As far as I am aware the cut off circuit to which the info is relayed from the battery once fully done is in the plug unit rather than in the amp. It could mean the battery gets ‘overcharged’ and I am not sure what implications this would have! It could be very bad, and a lot of heat and maybe worse happening.
> I could be wrong of course, I’m certainly no electronics wizard, but I wouldn’t want to find out......


Now I am running out of options...


----------



## Yobster69 (May 16, 2018)

rafaelo said:


> Now I am running out of options...


I have found the charge connection a bit temperamental myself. It sometimes comes up with a green light straight away, even though I know the battery is low, but I found lightly twisting the connector in the socket until the red light comes on to work, and then instantly leave it. I do not touch it again until the green light shows, even then I’ll unplug it and plug it in again to check.
You should get 4-5 hours play, and all I can think is it may be is a faulty battery if this doesn’t work.
Though, and I must say I am religious about this, I always charge the battery of any new device fully before using it. As I n the past I have used items straight out of the box (even electric toothbrushes) without charging them and subsequently found the battery to be a bit naff afterwards!! It might have been that you discharged it without charging first??


----------



## rafaelo

Yobster69 said:


> I have found the charge connection a bit temperamental myself. It sometimes comes up with a red light straight away, even though I know the battery is low, but I found lightly twisting the connector in the socket until the green light comes on to work, and then instantly leave it. I do not touch it again until the red light shows, even then I’ll unplug it and plug it in again to check.
> You should get 4-5 hours play, and all I can think is it may be is a faulty battery if this doesn’t work.
> Though, and I must say I am religious about this, I always charge the battery of any new device fully before using it. As I n the past I have used items straight out of the box (even electric toothbrushes) without charging them and subsequently found the battery to be a bit naff afterwards!! It might have been that you discharged it without charging first??


Hmm... maybe but not sure about that. If it is a lithium battery could not be damaged like that. If not is better to charge from empty state I thought. In any case not to be destroyed so fast and such a big difference. The battery is not functional at all now. 

I raised the volume a bit to make the tubes work like zeo suggested and I thought I burned something but since you guys use it at max power then I did not do something wrong here.

I will play with adaptors and see what is happening.


----------



## jamonbread (May 16, 2018)

Yobster69 said:


> I have found the charge connection a bit temperamental myself. It sometimes comes up with a red light straight away, even though I know the battery is low, but I found lightly twisting the connector in the socket until the green light comes on to work, and then instantly leave it. I do not touch it again until the red light shows, even then I’ll unplug it and plug it in again to check.
> You should get 4-5 hours play, and all I can think is it may be is a faulty battery if this doesn’t work.
> Though, and I must say I am religious about this, I always charge the battery of any new device fully before using it. As I n the past I have used items straight out of the box (even electric toothbrushes) without charging them and subsequently found the battery to be a bit naff afterwards!! It might have been that you discharged it without charging first??



I thought the red light means its charging and green means its done, at least it works like that for me? When removing the amp form the charger, the LED on the charger plug turns from red to green, It's always green when nothing is attached to it and turns green when the amp is fully charged. My included charger came with a barrel adaptor off the seller.


----------



## rafaelo (May 16, 2018)

jamonbread said:


> I thought the red light means its charging and green means its done, at least it works like that for me? When removing the amp form the charger, the LED on the charger plug turns from red to green, It's always green when nothing is attached to it and turns green when the amp is fully charged. My included charger came with a barrel adaptor off the seller.


 
You are correct. First time I did not read the instructions just plug it to charge not even paying attention to colours. Now I read the instructions I know it should be like that. When I unplug it is always green I remember this. Last night I thought the opposite so touched the connector to be green light all night so to charge like that. I was wrong the opposite happens.

Also correct there is a barrel adapter, I have plenty of that maybe that is the problem for sensitive touch I will experiment tonight .

Thanks for your comments and thank to all of you guys that respond so quickly with helpful advise.


----------



## rafaelo (May 16, 2018)

jamonbread said:


> Does anyone know what the 4 adjustments are for on the little bear B4, do any of them adjust the gain for using lower ohm cans?



I have no clue about this but I tried IEMatch in order to tackle this issue differently but I thought that I burned or drain the battery that way. Today though I did not use IEMatch at all but obviously did not charge my battery or my battery went bad. Now obviously, I cannot recommend this solution until I make it work but in my case did not work because of a bad battery .


----------



## frogmeat69

For my amp it needs to be leaning on a book with volume side leaning upwards and the cord across the table to make contact for it to charge, pretty crappy connection in the unit it seems.
 And yes, it needs to be red for charging, then it turns green for full charge.


----------



## jamonbread

rafaelo said:


> You are correct. First time I did not read the instructions just plug it to charge not even paying attention to colours. Now I read the instructions I know it should be like that. When I unplug it is always green I remember this. Last night I thought the opposite so touched the connector to be green light all night so to charge like that. I was wrong the opposite happens.
> 
> Also correct there is a barrel adapter, I have plenty of that maybe that is the problem for sensitive touch I will experiment tonight .
> 
> Thanks for your comments and thank to all of you guys that respond so quickly with helpful advise.




You could try contacting the seller about a replacement battery, I got my  B4 amp off an ebay seller, and I ended up with a crackly volume pot after months of use. I wasn't able to get contact cleaner into the pot to fix the issues, I contacted the seller on ebay, and he sent me two replacement pots with the same spec as the original. It might also be worth looking on aliExpress for batteries that have the same spec, but I'd definitely give the seller a chance first.


----------



## rafaelo

jamonbread said:


> You could try contacting the seller about a replacement battery, I got my  B4 amp off an ebay seller, and I ended up with a crackly volume pot after months of use. I wasn't able to get contact cleaner into the pot to fix the issues, I contacted the seller on ebay, and he sent me two replacement pots with the same spec as the original. It might also be worth looking on aliExpress for batteries that have the same spec, but I'd definitely give the seller a chance first.


Is easy to change battery and if yes are any better as an upgrade with bigger capacity  available ?


----------



## jamonbread (May 16, 2018)

rafaelo said:


> Is easy to change battery and if yes are any better as an upgrade with bigger capacity  available ?



Its easy to replace if you can find the right battery, the one inside the B4 has a plug connection. I found one on AliExpress that's 1000mAh 12v, it also has 12.6v on the label. It looks the same, but lacks the mini plug with just bare ended live and neutral wires coming from the battery. Its £27 for 2 with free global shipping, works out about £14 per battery. The label looks identical to the one my stock B4 battery
https://www.aliexpress.com/item/100...1b6c-4d67-854d-b3de2e033414&priceBeautifyAB=0

Edit: The one I linked is the same 1000mAh capacity as the stock battery, getting a higher capacity could be tricky as the included battery is a fairly tight fit as it is, anything with a higher capacity would probably mean a larger overall size.


----------



## Yobster69

jamonbread said:


> I thought the red light means its charging and green means its done, at least it works like that for me? When removing the amp form the charger, the LED on the charger plug turns from red to green, It's always green when nothing is attached to it and turns green when the amp is fully charged. My included charger came with a barrel adaptor off the seller.


You are absolutely correct of course, apologies, I’m at work so cannot actully try it and I got my red and greens messed up. I have edited my original post to reflect this. 
Thank you


----------



## rafaelo

jamonbread said:


> Its easy to replace if you can find the right battery, the one inside the B4 has a plug connection. I found one on AliExpress that's 1000mAh 12v, it also has 12.6v on the label. It looks the same, but lacks the mini plug with just bare ended live and neutral wires coming from the battery. Its £27 for 2 with free global shipping, works out about £14 per battery. The label looks identical to the one my stock B4 battery
> https://www.aliexpress.com/item/100...1b6c-4d67-854d-b3de2e033414&priceBeautifyAB=0
> 
> Edit: The one I linked is the same 1000mAh capacity as the stock battery, getting a higher capacity could be tricky as the included battery is a fairly tight fit as it is, anything with a higher capacity would probably mean a larger overall size.


That is great information in any case but this is almost half price of a new unit and some extra hassle. I believe that it did not manage to charge propwely yet otherwise is better to return or refund at the moment.


----------



## rafaelo (May 16, 2018)

The trick seems to be that is should not be fully inserted. And not moved afterwards. Let's see if it is red for a couple of hours means that it might work at the end.


----------



## jamonbread

rafaelo said:


> That is great information in any case but this is almost half price of a new unit and some extra hassle. I believe that it did not manage to charge propwely yet otherwise is better to return or refund at the moment.


 
You could ask the seller on Ali if he can sell you one battery for £14 as the listing is for two, but I'd contact the seller you purchased the amp off first, he might even be willing to send you a replacement battery without the hassle and cost of posting the amp back to China.  Did you buy your B4 amp off AliExpress, or ebay? 

I brought mine off an ebay seller called doukmall, and customer service was great, he sent me two replacement volume pots for free.


----------



## rafaelo (May 17, 2018)

jamonbread said:


> You could ask the seller on Ali if he can sell you one battery for £14 as the listing is for two, but I'd contact the seller you purchased the amp off first, he might even be willing to send you a replacement battery without the hassle and cost of posting the amp back to China.  Did you buy your B4 amp off AliExpress, or ebay?
> 
> I brought mine off an ebay seller called doukmall, and customer service was great, he sent me two replacement volume pots for free.


4,5 plus hours of playing today (but in lower volumes, around 10 o clock) so the battery is probably fine. It helps when you charge the battery otherwise...suprise suprise ...does not play...

But charging is difficult I need to play with the barrel adaptor when I have time. I will upgrade the opamp when I feel more confident about the devise. 

I bought mine from Amazon. Instead of battery replacement/upgrade I prefer to order a b5 one. My understanding is that B5 the battery keeps a lot longer, is slimmer design, less powerful and the opamp is not upgradable. Is that right?

Does anyone know how sound quality wise they are comparing?


----------



## Yobster69

rafaelo said:


> 4,5 plus hours of playing today (but in lower volumes, around 10 o clock) so the battery is probably fine. It helps when you charge the battery otherwise...suprise suprise ...does not play...
> 
> But charging is difficult I need to play with the barrel adaptor when I have time. I will upgrade the opamp when I feel more confident about the devise.
> 
> ...


I considered it as well, but reports I have read are not good. Lots of hiss among other issues. 
Do your research though, there are comments in this thread about the B5 and decide for yourself. I’m not trying to put you off, but personally I would swerve it.


----------



## Sylaw

hi.. i recently purchased a Sennheiser HD700. and i found it to be  quite treble peaky. I was thinking of using a Little bear B4 and a fiio A3 together. is it a dumb idea? as in i will use my lg v10 as my dac and will feed that straight into the tube amp and that signal will route to the fiio a3 ( to clean up any distortion & make it a bit accurate - like a hybrid setup) and then plug the hd700s into the fiio a3.  Are there any issues if i use these  two amps parallely?


----------



## frogmeat69

Sylaw said:


> hi.. i recently purchased a Sennheiser HD700. and i found it to be  quite treble peaky. I was thinking of using a Little bear B4 and a fiio A3 together. is it a dumb idea? as in i will use my lg v10 as my dac and will feed that straight into the tube amp and that signal will route to the fiio a3 ( to clean up any distortion & make it a bit accurate - like a hybrid setup) and then plug the hd700s into the fiio a3.  Are there any issues if i use these  two amps parallely?


The Little Bear is a hybrid tube amp.


----------



## Wiljen

You might also check out the ModHouse mod for the HD700 - fully reversible and it smooths them out a bit.   I have the mod on mine and think it helps.


----------



## Sylaw

frogmeat69 said:


> The Little Bear is a hybrid tube amp.





Wiljen said:


> You might also check out the ModHouse mod for the HD700 - fully reversible and it smooths them out a bit.   I have the mod on mine and think it helps.



So you guys think running the fiio A3 and Little bear B4 together wont benefit the sound by any means?


----------



## rafaelo

Sylaw said:


> So you guys think running the fiio A3 and Little bear B4 together wont benefit the sound by any means?


My little bear smooths the treble from my Meze 12 classics. But so does the xDSD. 

It seems to me an overkill two amps on the row, the little bear amp seems more than enough .if you want more smoothness work and improve the DAC part. Ifi products sound so good not only because of the DAC but because of the asyncronous clock (or in Bluetooth mode the master clock at the end tries somehow to clean the signal and make the same effect). 


Again the Meze classics 12 sounded sweet with only the xDSD, actually even warmer like a tube amp. Or you can use them together like shown in the photo. xDSD working in line out mode so DAC + preamp but you are focusing on the DAC part here.

However, I cannot offer you conclusions only suggestions because my little bear is not burned in properly yet and I did not change the opamp yet so I do not know the full potential yet.

So you have a couple of different ways to attack this problem. My HE4XX supposed to be bright but in my systems does not sound bright in a negative sence. Just sweet and lively.

Next step for me is to use the Radsone es100 with little bear. I am also looking forward to your valuable comments guys with the different opamps configurations. Any feedback will be appreciated.


----------



## frogmeat69

Sylaw said:


> So you guys think running the fiio A3 and Little bear B4 together wont benefit the sound by any means?


You are just double amping, not sure how that would help, probably create more issues soundwise. Have you tried  just the B4 with your phone and new HD700's yet? How was it to you?


----------



## Wiljen

Sylaw said:


> So you guys think running the fiio A3 and Little bear B4 together wont benefit the sound by any means?



No, I don't think using both will help and there is a fundamental misunderstanding in your earlier statement.   Putting another amp in the chain is not going to clean up or remove distortion, it simply is not possible.  Once distortion is introduced into the signal, it would require a DSP to remove it again (while likely adding some other form of artifact).   You would be better off using a different amplifier rather than 2 in a chain as using two devices just introduces the faults of both rather than removing the faults of either.


----------



## Sylaw

Wiljen said:


> No, I don't think using both will help and there is a fundamental misunderstanding in your earlier statement.   Putting another amp in the chain is not going to clean up or remove distortion, it simply is not possible.  Once distortion is introduced into the signal, it would require a DSP to remove it again (while likely adding some other form of artifact).   You would be better off using a different amplifier rather than 2 in a chain as using two devices just introduces the faults of both rather than removing the faults of either.



Understood....! thank you sir


----------



## silverfishla

Sylaw said:


> So you guys think running the fiio A3 and Little bear B4 together wont benefit the sound by any means?


Why don't you just try it?  Think of the Little Bear like a tube pre-amp to your other amp.  I use it this way on my Denon stereo amplifier at home (Denon is a little cold sounding).  It warms up the sound and makes it sound more full.  I use a Sparkos or a Burson Opamp in the Little Bear.  If you're going to "double amp", this one is not a bad one to do it with.


----------



## rafaelo

silverfishla said:


> Why don't you just try it?  Think of the Little Bear like a tube pre-amp to your other amp.  I use it this way on my Denon stereo amplifier at home (Denon is a little cold sounding).  It warms up the sound and makes it sound more full.  I use a Sparkos or a Burson Opamp in the Little Bear.  If you're going to "double amp", this one is not a bad one to do it with.


Oops you said the magic word...sparkos...

I was thinking to upgrade with burson opamp until I was brain washed by the katana dyi thread regarding sparkos superiority.

Can you elaborate a little bit further please? Provide some comparison and a link where to buy sparkos for little bear? Many thanks in advance.


----------



## silverfishla

rafaelo said:


> Oops you said the magic word...sparkos...
> 
> I was thinking to upgrade with burson opamp until I was brain washed by the katana dyi thread regarding sparkos superiority.
> 
> Can you elaborate a little bit further please? Provide some comparison and a link where to buy sparkos for little bear? Many thanks in advance.


I bought my Sparkos Labs dual opamp off of eBay here in America.  It’s actually Sparkos Labs that does the listings.  I think your best bet is to go straight to their webpage unless you can access that listing off of UK eBay.
The Sparkos just makes the Little Bear very coherent.  Brings up all the levels from highs to bass and has a big spacious and upfront sound.  The Burson is more delicate.  Spacious and emotional (the vocals are great).


----------



## rafaelo

silverfishla said:


> I bought my Sparkos Labs dual opamp off of eBay here in America.  It’s actually Sparkos Labs that does the listings.  I think your best bet is to go straight to their webpage unless you can access that listing off of UK eBay.
> The Sparkos just makes the Little Bear very coherent.  Brings up all the levels from highs to bass and has a big spacious and upfront sound.  The Burson is more delicate.  Spacious and emotional (the vocals are great).


Thanks so much for this useful info. I have no clue what dual opamp means though. Can I use a dual opamp in little bear? 

I have seen also in eBay dual opamp for burson audio but I thought from the picture there are two opamps to place if you have two sockets available. Apologies in advance for my naive questions.


----------



## frogmeat69 (Jun 24, 2018)

There is one socket in the Little Bear B4, and it takes a dual op amp, so for Sparkos you would need the SS3602, and Burson you would probably stick with the V5i dual, since the V5 or V6 would not fit inside.
BTW, do these discrete op amps use any more power, so less play time on a charge? Haven't swapped in my V5i yet, just curious.


----------



## silverfishla

rafaelo said:


> Thanks so much for this useful info. I have no clue what dual opamp means though. Can I use a dual opamp in little bear?
> 
> I have seen also in eBay dual opamp for burson audio but I thought from the picture there are two opamps to place if you have two sockets available. Apologies in advance for my naive questions.


Yes, you'll want the dual opamp not the single type opamps.





frogmeat69 said:


> There is one socket in the Little Bear B4, and it takes a dual op amp, so for Sparkos you would need the SS3602, and Burson you would probably stick with the V5i dual, since the V5 or V6 would not fit inside.
> BTW, do these discrete op amps use any more power, so less play time on a charge? Haven't swapped in my V5i yet, just curious.


Yes, the discrete opamps use a little more power.  I know this because it is apparent when using them in a Zishan Z3, but I'm not sure how much it really affects the Little Bear.  I haven't done a comparison with that amp and the discrete opamps.  I've never bled out a battery on a listening session so far, but sorry, I can't tell you specifics.


----------



## rafaelo

frogmeat69 said:


> There is one socket in the Little Bear B4, and it takes a dual op amp, so for Sparkos you would need the SS3602, and Burson you would probably stick with the V5i dual, since the V5 or V6 would not fit inside.
> BTW, do these discrete op amps use any more power, so less play time on a charge? Haven't swapped in my V5i yet, just curious.


Superb information, thanks so much!!!


----------



## anorphirith (Jun 25, 2018)

I just got my B4 and love it so far, I sometimes even use it at home to smoothen the sound from my SS desktop amp
I did have a couple questions:
-Is there any way that they could fail and damage my headphones ? (40ohm abyss diana)
-Anyone has the circuit diagram
-I'm thinking of removing the plastic window and putting a burson V6 vivid oAmp in it. does anyone makes an angled connector so I could keep the window on?
-Any other parts I could upgrade besides the oamp ?


----------



## frogmeat69 (Jun 25, 2018)

Burson sell an extension on their website that is flexible, you will find it under accessories, 2 for $20 plus shipping, order them with your op amp, not sure about the V6 flopping around in there, something to think about,   https://www.bursonaudio.com/products/supreme-sound-opamp-v5/


Or something like this?? https://www.digikey.com/product-det...g-corp/299-93-308-10-001000/ED58408-ND/248999


----------



## anorphirith

frogmeat69 said:


> Or something like this?? https://www.digikey.com/product-det...g-corp/299-93-308-10-001000/ED58408-ND/248999


that's perfect ! 
that's the best I could find on mouser 
https://www.mouser.com/ProductDetai...=sGAEpiMZZMs/Sh/kjph1tvt1/mEPT/XoFM84z5JrlW4=


----------



## anorphirith

anyone tried the muses opamps ? 
https://www.njr.com/MUSES/index.html


----------



## Wiljen

I have the muses02 and find it to be on par with the best of the customs, but it ought to be at the price point.   I did a compare and contrast of the burson v5i, and V6c/V6v vs the Muses in my review of the Burson products awhile back.
https://www.head-fi.org/showcase/burson-op-amps.22984/reviews#review-20028
https://www.head-fi.org/showcase/burson-op-amps.22984/reviews#review-20028


----------



## rafaelo

Hi guys,

I just received my burson audio V5i dual and I want to install it. Do I need a torx T5 or T6 or a hex (number ?) screwdriver ? Or something else? 

Thanks very much in advance for your valuable help.


----------



## rafaelo (Jul 16, 2018)

slinkyjynx said:


> For anyone considering it, just do it. The difference is insane, super easy to fit too. Just b



Thanks so much for your picture. Made my change much much more easier .  I will start testing the new opamp from today.


----------



## rafaelo

I will write a review for the Burson Audio V5i dual opamp in the related thread when I fully complete the testing however it does not take more than one day to realise that in comparison with the shipped opamp of the little bear the Burson Audio is a game changer regarding the sound quality.

So I totally agree with other people in this thread that already said that they find the change of the op amp as a must. It is a real game changer.

Only negative thing is that in my (our) case, yes the battery life is shorter when this opamp is used with the little bear. But this is related to a specific case and thus I cannot deduce points from V5i because of this.

I experienced a lot of dramatic improvements lately with one being using balanced cables in combination with my Radsone es100 Bluetooth adapter instead of regular cables. The improvement in sound quality was dramatic not because of the balanced cable per se but because of this particular device working so much better in the balanced mode. However, using the same cable with a small adaptor that converts balanced to unbalanced in order to be used with little bear, the change in sound was even more dramatic with the new opamp from burson audio installed. This new opamp drastically transformed the sound after one day that was being installed. It was simply like I was changing amplifier in my main system.

Similarly, going from a crappy AV onkyo budget amplifier to my Marantz 6005 pm in my main system I noticed the same improvement with this new opamp. Or is like going from a budget Marantz stereo amp to using a Hegel amplifier. The reviewers before me were really spot on when they describe that the most notable improvement is associated with the clarity in the guitars and in musical instruments in general. Separation and analysis is on another level. 

But I have to say that I feel that the little bear is not exploiting fully the dual V5i. Currently, I am wondering in which device I could place this opamp which also would use a linear power supply in order to exploit fully the dynamics of this opamp. I have the intuitive feeling that it needs more power to further shine.

Obviously, my limitations as a reviewer is that I do not have other opamps to compare. I was looking at sparkos before but personally I would NOT pay around 80$ for an opamp for the little bear. The price of Burson Audio seems very reasonable in comparison. Also, the Burson audio has a nice beautiful silver cap that helps also with the orientation in installation that I think sparkos does not have. So I already did my choice before receiving this unit and from the point of view of a "customer reviewer" I believe that V5i is a no brainer for someone that has already the little bear b4 and as far the sound quality is conserned.

I have no xDSD in at the moment for testing to compare with the little bear + Burson audio opamp but this might change in the future. That would be really an interesting comparison since I have in such high esteem the xDSD and ifi audio products in general. However, although is quite early in my testing I would not exclude the possibility that a es100+little bear+burson audio V5i could be a giant killer when the cost is also put under consideration.

I am very grateful to Charles and the Burson Audio team for providing me this opportunity and I will write a proper review in the following weeks.

A final point I have to make is unrelated to this opamp and is that also to my big surprise the analogue cable connecting the little bear with my source makes a difference!!! Although, I was so happy having this small 10 cm cable provided I discovered that a budget 3m from Amazon circa 7£ improve the sound considerably. My point is not going crazy and spend money in audiophile expensive cables but if a cable is super super  budget might influence the sound. And I believe not all of us we have the same generic cable provided. I just used by accident one budget Amazon 3m cable that I just happened to have and the sound was better even if I was going from a 10cm to 3m cable!!!


----------



## rafaelo

I have just published my review for the Burson Audio V5i Dual opamp in the relevant thread:

https://www.head-fi.org/showcase/burson-op-amps.22984/reviews#review-20758


----------



## jj69

Just received my B4. Right out of the box, it seems my right channel is intermittent. Common problem?


----------



## jj69

Im still getting an intermittent connection with my B4. Seems to be a common problem.  Are they all just like this???


----------



## Yobster69

jj69 said:


> Im still getting an intermittent connection with my B4. Seems to be a common problem.  Are they all just like this???


Not at all, my B4 has worked flawlessly for around a year now. 
They are dead easy to open up and take a look to see if there is a faulty soldering point on the headphone jack. It’s all I can think of that may be an issue. 
I hope you can sort it


----------



## rafaelo (Sep 4, 2018)

jj69 said:


> Im still getting an intermittent connection with my B4. Seems to be a common problem.  Are they all just like this???





rafaelo said:


> One other thing I noticed is that when I touched the connection in my headphones the music stops for a second. Is that bad unit or normal with this unit?





slinkyjynx said:


> Music should not stop at all. One thing that isnt clear with the little bear is when you plug your headphone and input in, you need to push quite firmly to get a 'click' for the full connection, then its rock solid. Try pushing it in a bit more so you get the click, and then it shouldn't cut out.



I had a similar problem in the beginning but one member helped me with his advice copied above. Just make certain that the connection is firm. My unit so far is flawless and after the V5i upgrade is very possibly a giant killer.


----------



## plutonim

anorphirith said:


> -Anyone has the circuit diagram


----------



## ledzep

Anyone changed the tubes for a different manufacturer ? Heard the nos GE are supposed to be good, I intend to strip it down and replace the solder for silver and see what components can be upgraded, I know its overkill but I like messing with stuff.


----------



## silverfishla

ledzep said:


> Anyone changed the tubes for a different manufacturer ? Heard the nos GE are supposed to be good, I intend to strip it down and replace the solder for silver and see what components can be upgraded, I know its overkill but I like messing with stuff.


I have not, but I’ve thought about it.  Let us know the results when you do the swap.  One thing, be careful with the traces on the board, they are pretty easy to lift off.  I’ve changed the caps on mine and on a second pass (2nd swap) I lost a trace even though I was being pretty careful about it.  Good luck!


----------



## ledzep

silverfishla said:


> I have not, but I’ve thought about it.  Let us know the results when you do the swap.  One thing, be careful with the traces on the board, they are pretty easy to lift off.  I’ve changed the caps on mine and on a second pass (2nd swap) I lost a trace even though I was being pretty careful about it.  Good luck!



Thanks, I've got a full electronics lab at my disposal so that won't be a problem. Swapped the op amp for a V5i dual already but if there is a chance of improving the tubes I'm all in for that ! It's got half decent components in already for the price but nothing wrong with a little play with it, what caps did you swap and what improvement have you noticed ?


----------



## plutonim

ledzep said:


> what caps did you swap and what improvement have you noticed ?


Try to change the filament power supply  scheme and you will be  pleasantly surprised.
Besides, I had to change the output opamp to muses8920. 
The sound became more spacious and deeper.


----------



## silverfishla

ledzep said:


> Thanks, I've got a full electronics lab at my disposal so that won't be a problem. Swapped the op amp for a V5i dual already but if there is a chance of improving the tubes I'm all in for that ! It's got half decent components in already for the price but nothing wrong with a little play with it, what caps did you swap and what improvement have you noticed ?


These are the caps I’ve got in there now with a Sparkos opamp.  The difference from stock would be a perceived spaciousness and bit of bass improvement (that’s aside from the opamp change).


----------



## ledzep

silverfishla said:


> These are the caps I’ve got in there now with a Sparkos opamp.  The difference from stock would be a perceived spaciousness and bit of bass improvement (that’s aside from the opamp change).



Thanks for the schematic I'll have a look see what else I can do with it, I'm in the process of trying to prise a pair of Mullard 5899's and 4  GE 5899's off a friend of a friend who's got some nos stuff from his radio ham days, word has it he's got a load of hifi gear vintage and mint in a lock up he's collect over the years and wants to sell stuff due to a downsizing.


----------



## rafaelo

ledzep said:


> I'm in the process of trying to prise a pair of Mullard 5899's



Curious to hear the results with the Mullard valves although I am not sure if I can ever manage to change mine in B4.  In my living room set up though they shine.


----------



## ledzep

rafaelo said:


> Curious to hear the results with the Mullard valves although I am not sure if I can ever manage to change mine in B4.  In my living room set up though they shine.


Noticed the trimmer pots marked did you have a play with them ?


----------



## rafaelo

ledzep said:


> Noticed the trimmer pots marked did you have a play with them ?


If you refer to my picture, Not at all I am not a dyi guy just changed the opamp which is very easy with the right tools. 

In my Chinese cheap preamp at my main system is so easy to change valves so I tried both GE and Mullard and I liked Mullard so much that I am biased in favour of them. I do not even have the tools to change them for the B4 although I am very tempted.

I am pretty sure that dyi capable people like you can improve the sound even further by substituting better components.


----------



## ledzep

Today starts the modding of the little bear b4, probably very much an overkill venture on an amp that is cheap, but it's more of a see what can be done with a few £'s to make it that bit better as I think it's got potential. Updated will probably be a bit on the slow side as I'm busy at work but will do a bit of work on it in my breaks.
So first stage is shielding, try to cut down on the RF interference from the phones and WiFi around the house amongst other things. For now just the housing as i will be adding more later from the PCB ground to the chassis but I've got caps to replace so I'll leave that for now.
High grade copper tape used, fits nicely and looks good.

 
More later .... Break over now


----------



## ledzep

Stage 2 got home and waiting for me was the high temp O rings for tube damping, was going to stake the tubes to the PCB originally with sma staking gel and bake it but they will be getting taken out at some point and not a good idea if I'm doing a little rolling in the future, so settled on 9mm rings and a bit of hot glue to secure just in case they lose their grip ( shouldn't they are snug) but just in case.

Oh and this turned up as well !


A nice new Burson V5i dual op amp !
New set of higher quality Nichicon  capacitors on the way which is the next step, more soon !


----------



## ledzep

Couldn't resist putting it in and letting it run in for a while and settle in.


----------



## kukkurovaca

I recently picked up one of these, and it's....hmm. I dunno.

Plenty of power, including for Fostex RP drivers, which is good. And fit & finish is good for its price point.

But noise floor is quite high, and not just for sensitive IEMs; it's an issue with my B&O H6. It also seems to lack dynamic range? Not sure, I'm not a very technical listener.  Switching from the stock opamp to a V5i helped offset that, and in general definitely does improve performance. But there's also something weird in the frequency response in the sibilance area, that's annoying. 

I also messed around with the trim pots and while I have no idea what I'm doing with them, it does seem to have helped a bit, although it's hard to be sure since I can't do a direct comparison. It definitely did help ameliorate a channel imbalance that my unit had, though.

Overall, doesn't seem like a great value at over twice the price, size, and weight of a Walnut F1. (Of course putting tubes into the mix will do that, I'm just not sure the amount of tubiness provided is worth it here. : )

Out of curiosity, do folks know what changes have been made over time? The board on mine is dated June 2018 IIRC and said version 1.2.


----------



## ledzep

kukkurovaca said:


> I recently picked up one of these, and it's....hmm. I dunno.
> 
> Plenty of power, including for Fostex RP drivers, which is good. And fit & finish is good for its price point.
> 
> ...


I'd check your grounding and try to improve it, I had it at work today hooked up to a noise figure analyser and just by adding some copper tape to the grounding runner and chassis I dropped 3db.


----------



## kukkurovaca

ledzep said:


> I'd check your grounding and try to improve it, I had it at work today hooked up to a noise figure analyser and just by adding some copper tape to the grounding runner and chassis I dropped 3db.



Sorry, but...what's a grounding runner : )


----------



## ledzep

The PCB slides into the housing and at both sides it's got a ground rail that connects with the chassis. These amps are made quick and cheap and to be honest the soldering is appalling, way too much and I had to remove a few solder splashes and a lot of flux residue from both sides of the PCB but it works but with a bit of cleaning and modding it makes a nice little project to improve on. Look what Dan at Mr Speakers did with the fostex tp50's, I'll continue to mod this amp and have a play over the next few weeks and post my result asap.


----------



## kukkurovaca

ledzep said:


> The PCB slides into the housing and at both sides it's got a ground rail that connects with the chassis. These amps are made quick and cheap and to be honest the soldering is appalling, way too much and I had to remove a few solder splashes and a lot of flux residue from both sides of the PCB but it works but with a bit of cleaning and modding it makes a nice little project to improve on. Look what Dan at Mr Speakers did with the fostex tp50's, I'll continue to mod this amp and have a play over the next few weeks and post my result asap.



Thanks!


----------



## silverfishla

ledzep said:


> Today starts the modding of the little bear b4, probably very much an overkill venture on an amp that is cheap, but it's more of a see what can be done with a few £'s to make it that bit better as I think it's got potential. Updated will probably be a bit on the slow side as I'm busy at work but will do a bit of work on it in my breaks.
> So first stage is shielding, try to cut down on the RF interference from the phones and WiFi around the house amongst other things. For now just the housing as i will be adding more later from the PCB ground to the chassis but I've got caps to replace so I'll leave that for now.
> High grade copper tape used, fits nicely and looks good.
> 
> More later .... Break over now


Where are you planning on connecting your F Cage to the PCB?  Just wondering.


----------



## ledzep

Stage 3 today only had an hour spare so I just finalised the grounding, still need to add a bit more copper tape once the components are changed but for now after looking at the overall poor grounding it's time to hopefully put it to bed ! After checking the ground runner to housing with a meter I found the coating ( I have the  black amp ) quite resistive, so exactly how much grounding you get is a guess but I don't think much. So I scraped off some of the coating down to the aluminium and drilled a small hole, put a small screw in and soldered a 10 thou single core enameled copper link wire around it and sma staked it for securement , then soldered a small piece of copper shim to the runner  and linked the wire to that, job done ! Noise floor down another 1.3db need to hook up tonight and see if it's made a difference. Hopefully the new set of caps will be waiting for me at home to progress it further

Copper on inside of  battery cover to finish off the shielding.

Ground wire in place.
More to come later.


----------



## ledzep

Home now no caps ! 
Did change the screws in the housing to steel torx as the stock ones were starting to go a bit, think the silver looks good anyway.


----------



## ledzep

Tested it out last night with the a pair of 1770 pros with good results, better separation and more space a touch brighter but still has warmth to its signature. Just shows what better grounding can achieve, that vol pot needs a better one though it goes from silence to loud on an 1/8 of a turn. Anyone know what type of pot model number they use ?


----------



## ledzep

Here today 
 
Fit tomorrow !


----------



## ledzep

Caps fitted apart from the battery cap , board says 1000uf 10v , value of cap is 16v I understand why it's taking 12v across it, but I'm now thinking maybe the rest of the values might need a re evaluation to see more inprovements can be done.
 
 
Time to put it through its paces,
 
Results later !


----------



## ledzep

After doing some measurements the 2 caps each side of the volume pot are getting swapped out from the 10v to 16v, better stability and allows me to adjust the vo trimmer more and give some headroom to play with, a 10v cap is a bit low.


----------



## toear

Been looking at the b4.... Very cool!


----------



## ledzep

Well after leaving the amp playing ( burning in the caps ) overnight with a 32 ohm load on rather that hearing headphones leaking sound the results are in. This is only a brief review as I've still got the 10v caps to change to 16v so I can tweek the power input / output trimmers, feeding the little bear b4 with the line out of a Fiio X7II via a 7N copper lod and a pure silver lod and headphones getting used are a pair of Beyerdynamic DT1770 Pro 250 ohm. Music used is a selection of Rock , Pop, Classical, EDM. First up Rock Pink Floyd DSOM was using the SACD version sounded great, clear and precise good seperation vocals clear and keyboards had a really good transfer I could actually hear the press of the keys, drums and bass guitar had a nice warm thump but not a hint of muddiness really impressed. Pop was Thriller Japanese first pressing ( cd ) got the SACD of this but the rare Japanese first pressing is way better as the SACD is a bit brickwalled, the opening sounding the door creaking and footsteps on thriller sounded like it was in my front room, vocals crystal clear could hear Jackson breathing as he sang really impressed. Classical was Planet Suite Holst as the piece covers highs lows mids very well, was using the mfsl version listened to this twice as it sounded great just like vinyl with the analogue warmth. EDM etc  varied selection of Chase and Status, The Prodigy, Crystal Method etc sounded great and clear but this amp adds a touch of warmth which imo isn't suited to electronic music, don't get me wrong it sounds great but I found using a Fiio A5 had the edge. Will report more if any changes when I swap the caps and tweek the trimmers. Oh and the power of this amp is excellent pot only turned to 10 o'clock and more than enough juice to power the 250 ohm Beyers.


----------



## toear

Hi all, 

So I got my B4 today (Amazon... So I laud about $20cad more than from AE)... I took a quick listen and was very impressed! There seemed to be a slight channel imbalance that went away after the unit was on for a bit. I do have a spare Burson v5i which is one of the reasons I got it. But now that I have it... It is huge! My fault for not taking a closer look at the specs.

What I'm wondering is does anyone have a suggestion for a desktop tube amp with the same kind of performance? I just figure that is not functional to carry around anyway. I might as well look at a desktop option that does not have to be recharged....

Or I could deal with the size but it would realistically be limited to home use. 

Any suggestions? Or reasons to keep this instead of going to a desktop amp?

Thanks and much appreciated!


----------



## silverfishla

toear said:


> Hi all,
> 
> So I got my B4 today (Amazon... So I laud about $20cad more than from AE)... I took a quick listen and was very impressed! There seemed to be a slight channel imbalance that went away after the unit was on for a bit. I do have a spare Burson v5i which is one of the reasons I got it. But now that I have it... It is huge! My fault for not taking a closer look at the specs.
> 
> ...


I think it runs while plugged into the wall plug?  Sorry, haven’t tried it, just turned it on from a 0% battery and saw that it lit up while plugged in.  Not sure if it charges faster than it depletes.


----------



## ledzep

Nope doesn't run from the mains, you can only use it when you charge it up and un plug the adaptor, there is a work around so you can run it off the mains but you need to do a bit of soldering on the power supply area and unless you know what your doing don't bother, just charge unplug and enjoy. I've had 6 hours off a full charge but I've modified the PCB to make it more energy efficient.


----------



## toear

Craaapy... So I listened to the b4 for a good chunk of the day today with my Datura X... Awesome!

For home and decided to try some other earphones and cans... 70/30...most of my ear and headphones work... A bunch don't. Including my hd650s.... Whhhyyyyy?! 

I got them to work using an extender but this is not ideal. Guess it is going back. 

That said, for those who have trouble free units, you are very fortunate. I'm undecided if I should try for a second unit vs just getting a desktop setup....


----------



## kukkurovaca

toear said:


> For home and decided to try some other earphones and cans... 70/30...most of my ear and headphones work... A bunch don't. Including my hd650s.... Whhhyyyyy?!



What's your specific failure mode?


----------



## toear

kukkurovaca said:


> What's your specific failure mode?


One or no channel... Sometimes moving the jack around worked, or not at all. If it did work i had to hold it in place. As soon as I let go it would lose contact again


----------



## kukkurovaca

toear said:


> One or no channel... Sometimes moving the jack around worked, or not at all. If it did work i had to hold it in place. As soon as I let go it would lose contact again



If you have chunky audiophile cables, you may want to check the physical size of the plug housing. I found that I have one adapter (ALO 2.5mm->3.5mm) that's wide enough that it doesn't fit into the slightly recessed circle on the B4's front. It seems to connect, but it is not correctly seated.

It could also be that the jack is defective, although in that case you would kind of expect it to not work on a consistent basis.

Another thing that's useful for troubleshooting is if you have a 3.5mm male to female exender or splitter, try plugging that into the amp and the headphone into it.

Is there anything in common between the plugs on the headphones/cables that don't work? I'm guessing they're not TRRS if it includes your HD650, but that will also mess up some amps, so might as well mention it.


----------



## toear

Thank you for the suggestions. I have run through the options that I have. I do find it weird that my HD650 cable would be the one that does not work. I checked the sleeve and it did fit in the indentation on the b4.... Something internal has a poor contact...


----------



## ledzep

Remove the top and you will see the gold contacts on the headphone out, plug in your headphones and get a cocktail stick or something that isn't conductive and gently press down on each contact see which one is the problem then take out the jack and apply a touch of pressure to the one or two etc in question this should solve the problem, they are not the best of female sockets I have some switchcrafts on order to swap out.


----------



## Onik

I Installed SPARKOS SS3602 on my Little bear B4 but I get now sound What is wrong?


----------



## silverfishla

Onik said:


> I Installed SPARKOS SS3602 on my Little bear B4 but I get now sound What is wrong?


Is that the single or double?  It has to be the dual.  I have both, but am not home to check the item number.  Also, is it plugged in right side up?


----------



## ledzep

Onik said:


> I Installed SPARKOS SS3602 on my Little bear B4 but I get now sound What is wrong?



If it's in the correct orientation and making full pin contact I'd then try the op amp your replacing just to make sure it's the amp and not another component that's the problem. Were you grounded when you opened up the case for ESD protection ?


----------



## Onik (Nov 3, 2018)

ledzep said:


> If it's in the correct orientation and making full pin contact I'd then try the op amp your replacing just to make sure it's the amp and not another component that's the problem. Were you grounded when you opened up the case for ESD protection ?



I got the problem solved, B4s socket hole is not really tight and ss3602s legs aren't thick enough to fit in, and result was no sound. what I did was to put some small thermal pads on top of ss3602 have some extra pressure while closing the cover now it's working and sounding great.

edit:even with the pressure it failed to sit tight inside, the only way I was able to make it sit tight was to use extra op amp socket but it made it too tall and can't close the cover which sux but do the job. But now I am using LME49720HA instead, paired with my Colorfly C4.


----------



## Onik

ledzep said:


> If it's in the correct orientation and making full pin contact I'd then try the op amp your replacing just to make sure it's the amp and not another component that's the problem. Were you grounded when you opened up the case for ESD protection ?





silverfishla said:


> Is that the single or double?  It has to be the dual.  I have both, but am not home to check the item number.  Also, is it plugged in right side up?



SS3602 is a dual OPA.


silverfishla said:


> Is that the single or double?  It has to be the dual.  I have both, but am not home to check the item number.  Also, is it plugged in right side up?



its double single wouldn't work on b4.


----------



## ledzep

ledzep said:


> Well after leaving the amp playing ( burning in the caps ) overnight with a 32 ohm load on rather that hearing headphones leaking sound the results are in. This is only a brief review as I've still got the 10v caps to change to 16v so I can tweek the power input / output trimmers, feeding the little bear b4 with the line out of a Fiio X7II via a 7N copper lod and a pure silver lod and headphones getting used are a pair of Beyerdynamic DT1770 Pro 250 ohm. Music used is a selection of Rock , Pop, Classical, EDM. First up Rock Pink Floyd DSOM was using the SACD version sounded great, clear and precise good seperation vocals clear and keyboards had a really good transfer I could actually hear the press of the keys, drums and bass guitar had a nice warm thump but not a hint of muddiness really impressed. Pop was Thriller Japanese first pressing ( cd ) got the SACD of this but the rare Japanese first pressing is way better as the SACD is a bit brickwalled, the opening sounding the door creaking and footsteps on thriller sounded like it was in my front room, vocals crystal clear could hear Jackson breathing as he sang really impressed. Classical was Planet Suite Holst as the piece covers highs lows mids very well, was using the mfsl version listened to this twice as it sounded great just like vinyl with the analogue warmth. EDM etc  varied selection of Chase and Status, The Prodigy, Crystal Method etc sounded great and clear but this amp adds a touch of warmth which imo isn't suited to electronic music, don't get me wrong it sounds great but I found using a Fiio A5 had the edge. Will report more if any changes when I swap the caps and tweek the trimmers. Oh and the power of this amp is excellent pot only turned to 10 o'clock and more than enough juice to power the 250 ohm Beyers.




Well finally finished messing with the b4 so here is what i modded and final listening evaluation.
Swapped the op amp to a burson v5i
Changed all the caps to Nichicon's KA Series 16v 105 temp, better stabilty and allows me to tweek the power a bit.
Housing fully copper shielded and it was worthwhile put my mobile phone on the top and no interference... result !
Pcb fully cleaned removing old flux and solder splashes and corrected a few joints that were either a touch dry or over soldered.
High Temp damping rings x 4 added hot glue ( 200 deg melting point so tube heat won't affect).
RTV clear gel added to tips of tubes / pcb for added stability ( ching sound with knock / movement not noticable now)
Added grounding from pcb to chasis, this was a good move as it lowered the noise floor about 5db.
Had a play with the 4 trimmers to get a good combination of power and balance without distortion, did this on various genres of music to get a good balance from the low end to the highs, only moved them maybe a mm or two either way to find the final sweet spot.
Took out the vol pot and cleaned and re greased it, buttery smooth now and no sudden leap in volume ( tweeking the trimmers also helped in this area)
Finally changed the screws to steel torx and a nice new solid aluminium volume knob ( just looked better imo).

Then left the amp running for 10 charges to bed in the new caps and optimize the battery holding charge, i now have an amp that after switching on has no noise whatsoever from the click to the almost immediate low volume ( nicely graduated now no sudden blast) both channels fire up at the same time as well and stay balanced when i sweep up and down the volume scale. Ten o'clock was the max i needed for the 250 ohm 1770 pros and alpha primes to give them the correct drive to make them sing ! did push them a bit more and they stayed clear not that i'll ever use them at that volume but i had to try !
Bass has a nice punch with no muddiness or bleed and vocals are clear without any shrillness, electric guitars have a nice lively sounding ring to them and on the bass guitar on floyds money track i could clearly hear Waters going to town on the strings. All in all a worthy little project that i'm happy with, don't get me wrong if your expecting it to turn into a bottle head crack .....er no ! But it gives enough for me  now to keep going back to it just to see what my needle drops and more musical type of tunes sound like with a bit of warmth to it.


----------



## ledzep

I'm interested in the muse and the sparkos op amps as well , anyone tried all 3 ?


----------



## jj69

So how much would you charge if I send you my B4?



ledzep said:


> Well finally finished messing with the b4 so here is what i modded and final listening evaluation.
> Swapped the op amp to a burson v5i
> Changed all the caps to Nichicon's KA Series 16v 105 temp, better stabilty and allows me to tweek the power a bit.
> Housing fully copper shielded and it was worthwhile put my mobile phone on the top and no interference... result !
> ...


----------



## Carrow (Nov 3, 2018)

So should I get one of these? The price is good and apparently the sound is excellent but I've heard complaints about the battery, and I'm not about to spend money on anything I can only get 4 hours out of. 

edit: oh, and of course, which one because I know there are a few models in the lineup! I'd be using it stacked with an iBasso DX80.


----------



## Onik (Nov 3, 2018)

I think the b4 is only suitable for over ear headphones cus all my iems are not compatible with it, they all have constant white noise(high gain), how can I enjoy my iems with complete black background, should I use 11k resistors to reduce the gain?


----------



## silverfishla

ledzep said:


> I'm interested in the muse and the sparkos op amps as well , anyone tried all 3 ?


The Sparkos is big and bold.  Powerful sounding like all levels are raised.  The Burson is more atmospheric, where the vocals are very clear and bass has a swelling presence, but there’s more space between the instruments.  The Muses02 is clear and neutralish, but sounds “smaller” than the others, still good though.  I personally swap between the Burson and Sparkos, depending on what headphone or earbud I’m listening to.  I don’t use this amp with IEMs.


----------



## Carrow

Carrow said:


> So should I get one of these? The price is good and apparently the sound is excellent but I've heard complaints about the battery, and I'm not about to spend money on anything I can only get 4 hours out of.
> 
> edit: oh, and of course, which one because I know there are a few models in the lineup! I'd be using it stacked with an iBasso DX80.



Anyone?


----------



## ledzep

Carrow said:


> Anyone?


Getting 6.5 hours out of mine at present but I've modded it quite a bit.


----------



## Onik

silverfishla said:


> The Sparkos is big and bold.  Powerful sounding like all levels are raised.  The Burson is more atmospheric, where the vocals are very clear and bass has a swelling presence, but there’s more space between the instruments.  The Muses02 is clear and neutralish, but sounds “smaller” than the others, still good though.  I personally swap between the Burson and Sparkos, depending on what headphone or earbud I’m listening to.  I don’t use this amp with IEMs.



but SS3602 do not fit easily cus the legs aren't thick enough for the B4 OP AMPS Socket.


----------



## rafaelo

ledzep said:


> Well finally finished messing with the b4 so here is what i modded and final listening evaluation.
> Swapped the op amp to a burson v5i
> Changed all the caps to Nichicon's KA Series 16v 105 temp, better stabilty and allows me to tweek the power a bit.
> Housing fully copper shielded and it was worthwhile put my mobile phone on the top and no interference... result !
> ...


Great job!!! 

You did all the r&d for the manufacturer for free ...

But you did not change the tubes, did you?

For the hiss guys with iems I can suggest you to look for the ifi IEMatch, I have also a review for that in the relevant section.

About the battery, 6.5 hours with HD6xx it seems ambitious to me. With the burson opamp battery life seems even less although to be honest I am not listening a lot lately with the B4.


----------



## ledzep (Nov 6, 2018)

rafaelo said:


> Great job!!!
> 
> You did all the r&d for the manufacturer for free ...
> 
> ...



Left the tubes for the time being want to give them a good go first, didn't think 6.5 with the Beyer 1770 pros and Burson wasn't bad really, I could extend it further but it would need just a bit more modding / replacement than I can be bothered to do. I've spent around £50 on the Burson and caps and other bits and that's where I draw the line ( apart from tubes later ) but I'm happy with what the end result is, way too powerful for iems though imo, but it's for my over ear collection and for that it sounds great. Thinking of changing the trimmers to a better quality and slight different resistance so I can tweek a bit more accurately, I've found messing with the trimmers does improve the sound to my ears anyway. Nothing wrong with stock settings but I like to push it that bit further.


----------



## rafaelo

ledzep said:


> Nichicon's KA Series 16v 105



How much did you pay for those?


----------



## ledzep

£8 for 3


----------



## ledzep

Well had time to kill at work so I thought I'd change the trimmers for Vishay ones better quality more smoother and more accurate to get the power and balance better the stock were grating a bit plus in 20% tolerance where as the Vishay ones are 5% so better all round, will have a tune later.


----------



## kukkurovaca

Carrow said:


> Anyone?



Judging by my unit: unless you're up to heavier modding than just opamp swapping, yuck.


----------



## Onik

ledzep said:


> Well finally finished messing with the b4 so here is what i modded and final listening evaluation.
> Swapped the op amp to a burson v5i
> Changed all the caps to Nichicon's KA Series 16v 105 temp, better stabilty and allows me to tweek the power a bit.
> Housing fully copper shielded and it was worthwhile put my mobile phone on the top and no interference... result !
> ...



Imo the the stock caps aren't bad but I wish I could fit V6 Vivids in it, but I will need to do some work for it.


----------



## ledzep

Tweeked the trimmers today with excellent results very accurate tuning of balance and no scratching, when dial is switched all the way down it stays balanced and totally black background and also more refined in getting that sweet spot, also was able to turn down the gain so I can use iems with it now without sacrificing power to supply big cans a definite worthwhile upgrade highly recommend.


----------



## Regnum

A friend had one of these but theirs ended up breaking within a week.


----------



## Manzabadman

ledzep said:


> Tweeked the trimmers today with excellent results very accurate tuning of balance and no scratching, when dial is switched all the way down it stays balanced and totally black background and also more refined in getting that sweet spot, also was able to turn down the gain so I can use iems with it now without sacrificing power to supply big cans a definite worthwhile upgrade highly recommend.



Hi led,
I have insulated my b4 with copper tape and changed the caps like you, I have noticed an improvement in sq and battery life and just wanted to ask where did you buy the trimmers ?
would any good 3 pin trimmer do or are they based on voltage etc


----------



## ledzep

Manzabadman said:


> Hi led,
> I have insulated my b4 with copper tape and changed the caps like you, I have noticed an improvement in sq and battery life and just wanted to ask where did you buy the trimmers ?
> would any good 3 pin trimmer do or are they based on voltage etc



You need surface mounted 3 pins 2x 200k 2x500k , I'll send you a link later


----------



## silverfishla

ledzep said:


> You need surface mounted 3 pins 2x 200k 2x500k , I'll send you a link later


Post it.


----------



## ledzep

https://ie.farnell.com/vishay/tsm4yl204kr05/trimmer-pot-200k-13turn-smd/dp/1141367
https://ie.farnell.com/vishay/tsm4yl504kr05/trimmer-pot-500k-13turn-smd/dp/1141368

I used these as we carry stock at work but there are different manufacturers that vary in price that you can use. Just make sure they are not single turn they are too sensitive the 13 turn are smooth and have plenty of play to be able to gradually get good results. If your not familiar with using trimmers a good starting point is to measure the resistance of the original trimmers and adjust the new ones to the same value before putting them on the PCB that way your not tuning blind just tweeking the stock settings so you don't get lost.


----------



## Manzabadman

ledzep said:


> https://ie.farnell.com/vishay/tsm4yl204kr05/trimmer-pot-200k-13turn-smd/dp/1141367
> https://ie.farnell.com/vishay/tsm4yl504kr05/trimmer-pot-500k-13turn-smd/dp/1141368
> 
> I used these as we carry stock at work but there are different manufacturers that vary in price that you can use. Just make sure they are not single turn they are too sensitive the 13 turn are smooth and have plenty of play to be able to gradually get good results. If your not familiar with using trimmers a good starting point is to measure the resistance of the original trimmers and adjust the new ones to the same value before putting them on the PCB that way your not tuning blind just tweeking the stock settings so you don't get lost.



Thanks for the links and advice ledzep
I found an upgraded version of the b4 - https://www.ebay.co.uk/itm/Little-B...ortable-Headphone-Amplifier-HiFi/283236997632

might be of some interest...


----------



## Onik

Manzabadman said:


> Thanks for the links and advice ledzep
> I found an upgraded version of the b4 - https://www.ebay.co.uk/itm/Little-B...ortable-Headphone-Amplifier-HiFi/283236997632
> 
> might be of some interest...



i just bought b4 wish ya sent it earlier!! is that real or fake??


----------



## Manzabadman

Onik said:


> i just bought b4 wish ya sent it earlier!! is that real or fake??


seems to be legit - I bought my b4 from their store (doukstore) about a month ago - I couldn't find this upgraded b4-x on Amazon or anywhere else for that matter so it's fairly new I suppose
- I will order it next week and put a review up if/when it comes


----------



## ledzep

Manzabadman said:


> Thanks for the links and advice ledzep
> I found an upgraded version of the b4 - https://www.ebay.co.uk/itm/Little-B...ortable-Headphone-Amplifier-HiFi/283236997632
> 
> might be of some interest...


Yeah thanks, would be interesting to hear the difference


----------



## plutonim

ledzep said:


> Yeah thanks, would be interesting to hear the difference


Balanced output and bipolar power supply of the amps must be interesting, but the filament power supply looks to be the same like in old version. 
Just try to powered each filament from stable power supply 6.3-6.4V and you will be surprised about sound improvment.


----------



## ledzep

Bought 4 V5i's need 3 so one is a  spare £30 with PayPal or £28 gift I'll cover shipping first come first served.


----------



## Onik

ledzep said:


> Bought 4 V5i's need 3 so one is a  spare £30 with PayPal or £28 gift I'll cover shipping first come first served.



duals or single?


----------



## ledzep

Onik said:


> duals or single?


Dual


----------



## Onik (Nov 11, 2018)

ledzep said:


> Dual



will you swap with me for a V6 Vivid SINGLE? Price-wise its same. btw I am from london.


----------



## ledzep

Onik said:


> will you swap with me for a V6 Vivid SINGLE?



Sorry no dont have use for a single


----------



## Onik

ledzep said:


> Sorry no dont have use for a single



Kool if no swap then Ill get it for £20 I don't wanna spend more than that as I am already receiving V5i review sample from Burson Audio.


----------



## ledzep

Sorry it's sold


----------



## Onik

ledzep said:


> Sorry it's sold


----------



## RobbS

Almost bought one for 11.11 but decided against it because of suspect quality. Anyone pick one up?


----------



## Soul Shinobi

I bought a Little Bear B4 on 11.11, and I have a Burson V5i Dual op-amp that I had bought for my XDuoo XD-05, but I may try it in the B4 first.


----------



## Onik

Soul Shinobi said:


> I bought a Little Bear B4 on 11.11, and I have a Burson V5i Dual op-amp that I had bought for my XDuoo XD-05, but I may try it in the B4 first.



To me the B4 with v5i felt like too aggressive but at the same time it was even more dynamic.

But on LD I+ the sound was softer and less aggressive.

But I need to let the v5i burn for few days to understand the true sound signature.

I’ll upload my review by next week.


----------



## Selmer52

Do any of you who have done some modding of the B4 know where I might be able to get a compatible UK plug charger? The charger they sent along with the amp has unfortunately gone "pop!" when I plugged it into the wall the other day


----------



## Manzabadman

Selmer52 said:


> Do any of you who have done some modding of the B4 know where I might be able to get a compatible UK plug charger? The charger they sent along with the amp has unfortunately gone "pop!" when I plugged it into the wall the other day



I seen this on ebay:
https://www.ebay.co.uk/itm/DC-12-6V...3d196b1b1:m:mrzuh3AGNGuFKjsNJP-ey1A:rk:6:pf:0
postage is from Hong Kong though and you probably would have to swap the tip


----------



## Onik

anyone tried the *Little Bear B4-X* yet?


----------



## Manzabadman

Onik said:


> anyone tried the *Little Bear B4-X* yet?



Waiting for mine to come - hopefully the trimmers will come tomorrow for me to finish modding the b4


----------



## Selmer52

Manzabadman said:


> I seen this on ebay:
> https://www.ebay.co.uk/itm/DC-12-6V...3d196b1b1:m:mrzuh3AGNGuFKjsNJP-ey1A:rk:6:pf:0
> postage is from Hong Kong though and you probably would have to swap the tip


Yes I seen that one - think the tip needed is 3.5mm x 1.35mm


----------



## waytoodeep03

So how does this b4 stack up to solid state amps like sony?


----------



## Onik

waytoodeep03 said:


> So how does this b4 stack up to solid state amps like sony?



f$%& SONY


----------



## kukkurovaca

waytoodeep03 said:


> So how does this b4 stack up to solid state amps like sony?



Stock, compares very unfavorably to any of my amps on any criterion except max power.


----------



## waytoodeep03

kukkurovaca said:


> Stock, compares very unfavorably to any of my amps on any criterion except max power.




I just got my b4 today from amazon.

This thing is crap. Static and buzzing and th volume level isnt much better than my lg v20.
The only thing i like is the size.


I guess im headed back to the drawing board looking for a good portable tube amp.


----------



## kukkurovaca

waytoodeep03 said:


> I just got my b4 today from amazon.
> 
> This thing is crap. Static and buzzing and th volume level isnt much better than my lg v20.
> The only thing i like is the size.
> ...



If you aren't up to the DIY work that is apparently needed to get the B4 running well, the best options are probably one of the Oriolus amps, or a used ALO, Cypher Labs, or Phatlab. Or the revised version of the IMS amp, but I don't know if that's actually available to buy. It seemed like he was having trouble fulfilling the Kickstarter orders for the desktop all-in-one version.


----------



## Onik

waytoodeep03 said:


> I just got my b4 today from amazon.
> 
> This thing is crap. Static and buzzing and th volume level isnt much better than my lg v20.
> The only thing i like is the size.
> ...




I only buy Chinese amps from ebay so far I never had any issues.


----------



## Selmer52

waytoodeep03 said:


> I just got my b4 today from amazon.
> 
> This thing is crap. Static and buzzing and th volume level isnt much better than my lg v20.
> The only thing i like is the size.
> ...



Thats really disappointing that you have had that experience with it. I must say I have nothing but excellent comments about the b4. HOWEVER - there can be static in one or both channels or popping/crackling, I was able to fix this by adjusting the pot screws. I would also suggest upgrading the opamp to a Burson V5i - D. I felt this really opened the sound up.


----------



## kukkurovaca

Selmer52 said:


> Thats really disappointing that you have had that experience with it. I must say I have nothing but excellent comments about the b4. HOWEVER - there can be static in one or both channels or popping/crackling, I was able to fix this by adjusting the pot screws. I would also suggest upgrading the opamp to a Burson V5i - D. I felt this really opened the sound up.



FWIW, I installed a V5i and also adjsuted the trim pots. Both help, but my unit is still a mess. But I haven't yet tried to improve the grounding with copper tape, as was suggested earlier in the thread and which is within even my limited DIY abilities. : )


----------



## Selmer52

kukkurovaca said:


> FWIW, I installed a V5i and also adjsuted the trim pots. Both help, but my unit is still a mess. But I haven't yet tried to improve the grounding with copper tape, as was suggested earlier in the thread and which is within even my limited DIY abilities. : )


I'm sorry to hear that  There are good units out there - I must just be one of the lucky ones, not withstanding the broken charger


----------



## MacAlwin (Nov 27, 2018)

Onik said:


> anyone tried the *Little Bear B4-X* yet?


Hi guys, I have received my B4-X yesterday. I left it on the charger overnight and then tried it with AK240 as a source and Shure 846 IEMs. Great tube sound. Battery lastet for 6 hours and 15 minutes


----------



## kukkurovaca

MacAlwin said:


> Hi guys, I have received my B4-X yesterday. I left it on the charger overnight and then tried it with AK240 as a source and Shure 846 IEMs. Great tube sound. Battery lastet for 6 hours and 15 minutes



Wow, no impedance or noise floor issues with the SE846?


----------



## MacAlwin

kukkurovaca said:


> Wow, no impedance or noise floor issues with the SE846?


I was also surprised. No noise floor hissing despite the super low impedance of only 9 ohm (? as far as I know) on the 846's. But maybe I just played the music too loud...


----------



## silverfishla

MacAlwin said:


> Hi guys, I have received my B4-X yesterday. I left it on the charger overnight and then tried it with AK240 as a source and Shure 846 IEMs. Great tube sound. Battery lastet for 6 hours and 15 minutes


What opamps does the B4X use?  Are they Singles or are they balanced opamps?


----------



## Onik

silverfishla said:


> What opamps does the B4X use?  Are they Singles or are they balanced opamps?



I doubt they are single


----------



## kukkurovaca

Onik said:


> I doubt they are single



Based on the Amazon description, appears dual.


----------



## MacAlwin (Nov 30, 2018)

silverfishla said:


> What opamps does the B4X use?  Are they Singles or are they balanced opamps?


Hi again, sorry for not introducing myself in my first post/reply. My name is Alwin, I am from Germany and have lived overseas for now 31 years. The last 19 years of those in Shanghai, China. I am a 2-channel music aficionado and listen mostly to Jazz, Blues and Classic (absolutely a Bach fan). My home stereo consists of an Audionet Art G3 CD player and a Transrotor Fat Boy turntable with a tube phonostage as my source. Backes&Műller Ice 802 pre amp, TAD MA2500 power amp an TAD CE1 speakers. Since I have to travel a lot, I am using an AK240 as a portable source and Shure 846's as IEM for my music needs... recently I added a Pioneer SE Master 1 but more for home use. I am a long time reader of head-fi threads. I was looking for a portable Headphone amplifier and stumbled here across a discussion about the Little Bear B4. Since I am an old tube fan I checked local websites  for the availbility of the B4... and found also the B4-X. Price was good (499 RMB, around 70 USD), so I just ordered one...

Now to the question: the opamp is a dual.

To me it sounds fantastic, has no flaws, stunning battery life (manufacturer told me 4 to 4.5 hours, mine did now twice slightly above 6 hours) and the looks are stunning for such a small device. Since some of you discussed the possibility of upgrading the B4 I checked with the manufacturer and he told me that it is very easy possible and that I should make sure that I would use Dual design opamps. I have ordered yesterday the Burson B5i's.

So, enough for today... have to go to bed now... it's 3 am


----------



## Onik

MacAlwin said:


> Hi again, sorry for not introducing myself in my first post/reply. My name is Alwin, I am from Germany and lived overseas for now 31 years. The last 19 years of those in Shanghai, China. I am a 2-channel music aficionado and listen mostly to Jazz, Blues and Classic (absolutely Bach fan). My home stereo consists of an Audionet Art G3 CD player and a Transrotor Fat Boy turntable with a tube phonostage as my source. Backes&Műller Ice 802 pre amp, TAD MA2500 power amp an TAD CE1 speakers. Since I have to travel a lot, I am using an AK240 as a portable source and Shure 846's as IEM for my music needs... recently I added a Pioneer SE Master 1 but more for home use. I am a long time reader of head-fix threads. I was looking for a portable Headphone amplifier and stumbled here across a discussion about the Little Bear B4. Since I am an old tube fan I checked local websites here for the availbility of the B4... and found also the B4-X. Price was good (499 RMB, around 70 USD), so I just ordered one...
> 
> Now to the question: the opamp is a dual.
> 
> ...



Good to Know that B4-X was worth buying for ya, I am now waiting for a real review to come out. btw it's *v5i.


----------



## MacAlwin




----------



## Onik

MacAlwin said:


>



did you try the balance out?


----------



## MacAlwin

Onik said:


> Good to Know that B4-X was worth buying for ya, I am now waiting for a real review to come out. btw it's *v5i.


sorry about that


----------



## MacAlwin

Onik said:


> did you try the balance out?


not yet, need to order a cable


----------



## MacAlwin

here comes a pic of the opamps


----------



## MacAlwin




----------



## BobpAmp (Dec 8, 2018)

Anyone else using a B5?  I just got mine in the mail and wondering how long for burn in?  It sounds really good although I have to admit when doing a comparison to the same song without the B5, it sounds great also. But the sound with the B5 is different, a little clearer in some instances. But then a little muddier in others too.... It seems to sound very good at low volume but can't seem to handle louder levels. Hoping this is due to not being burned in yet.

Some voices and certain drums seem to be sound great with a glowing quality. But then some sounds in the lower frequencies sound less smooth and even very slightly distorted.

And it's really tough to know how much is mental and how much is reality as I swear it sounds great....until a back to back comparison. Life is strange....

But no noise issues, hissing, cracking or popping at all. And no heat!  This thing runs so cool I'm a little worried it's not doing anything but I can hear a difference.  I think.

No, I actually can hear a difference but still waiting for burn in to improve things.  And researching about DIY mods to make it better.

Oh, listening so far on Samson SR850 phones, ipod 5g and Premium Spotify via Macbook Pro.

Hopefully this amp opens up as I love the size and looks.


----------



## MacAlwin (Dec 11, 2018)

Onik said:


> did you try the balance out?


Hi Onik, the balanced cables (Litz) for my 846's have arrived yesterday. The balanced output of the B4-X works well. Soundwise there is a little bit more distortion noticeable in the very low as well as in the very high frequencies. Don't know whether it is the cable or the amp. Ordered another balanced cable, this time copper, for the Shure's. Dynamics are good. I also noticed a very slight humming with no music playing. It is for me not noticable as soon as the music starts. Strange enough, if I cover the little window over the tubes with my hands, the humming stops.
Now I am waiting for the 2.5mm balanced cables for my HD800... I really assume this amp can drive them... let's see.


----------



## MacAlwin (Dec 11, 2018)

BTW, feeding the B4-X via "line out" from the AK240. Volume level increased dramatically...


----------



## kukkurovaca

MacAlwin said:


> Strange enough, if I cover the little window over the tubes with my hands, the humming stops.



Could be EM interference? Or grounding -- what happens if you touch other parts of the case?


----------



## Onik (Dec 11, 2018)

MacAlwin said:


> Hi Onik, the balanced cables (Litz) for my 846's have arrived yesterday. The balanced output of the B4-X works well. Soundwise there is a little bit more distortion noticeable in the very low as well as in the very high frequencies. Don't know whether it is the cable or the amp. Ordered another balanced cable, this time copper, for the Shure's. Dynamics are good. I also noticed a very slight humming with no music playing. It is for me not noticable as soon as the music starts. Strange enough, if I cover the little window over the tubes with my hands, the humming stops.
> Now I am waiting for the 2.5mm balanced cables for my HD800... I really assume this amp can drive them... let's see.




did you try with a different player other than AK240? I noticed humming on B4 when I charge and play with my portable DAC XDuoo Xd05. Try it in a place where you don't have any other electrical equipment.


----------



## MacAlwin

kukkurovaca said:


> Could be EM interference? Or grounding -- what happens if you touch other parts of the case?


if I touch other parts of the amp it has no effect. Only if I cover the small window with my hand...


----------



## MacAlwin

Onik said:


> did you try with a different player other than AK240? I noticed humming on B4 when I charge and play with my portable DAC XDuoo Xd05. Try it in a place where you don't have any other electrical equipment.


I have tried with my mobile phone... but that caused other interferences... I will try with my iPod tonight. I will organize some copper film and isolate the case from the inside and correct the grounding as someone did before (explained in this thread).


----------



## Onik

is the b4-x only for high impedance headphones or does it work with any iems without noise?


----------



## Origen Ru

My Little Bear B4 + OPAmp Burson V6 Dual Vivid + ZiShan DSD mod. Burson V5-i + Alessandro MS2e


----------



## MacAlwin

Onik said:


> is the b4-x only for high impedance headphones or does it work with any iems without noise?


Hi Onik, I am using the B4-X with IEM Shure 846 with very low impedance with no problems whatsoever. Sounds really good. Very light distortion, with a Tube touch. When I  am back home in China I will try it with my HD800 with TRRS balanced cable. Will let you know.


----------



## mandello

Hi, does anyone compared B4/B5 with aune B1?!?!?!


----------



## Soul Shinobi (Dec 23, 2018)

The Aune B1 is a solid state amp (even if it is class A), the similarities are only aesthetic (and the name, the name is similar). It does not sound like tubes, which are a completely different animal.

By the way I got my Little Bear B4 in from the 11/11 sale, I really like it. The difference is more subtle than expected but it's really smooth and musical. Very enjoyable for most genres, but I wouldn't recommend for energetic electronic music and the like.


----------



## mandello

Soul Shinobi said:


> The Aune B1 is a solid state amp (even if it is class A), the similarities are only aesthetic (and the name, the name is similar). It does not sound like tubes, which are a completely different animal.
> 
> By the way I got my Little Bear B4 in from the 11/11 sale, I really like it. The difference is more subtle than expected but it's really smooth and musical. Very enjoyable for most genres, but I wouldn't recommend for energetic electronic music and the like.


OK thanks, I already have a b1 and I m curious to listen to a b4 too..


----------



## Soul Shinobi

Today a friend and I were comparing his Schiit Vali 2 and my Little Bear B4. We liked the B4 better on every headphone we tried. I'm very happy so far; on the other hand, he just bought an upgraded tube for the Vali.


----------



## Eighty8

Soul Shinobi said:


> Today a friend and I were comparing his Schiit Vali 2 and my Little Bear B4. We liked the B4 better on every headphone we tried. I'm very happy so far; on the other hand, he just bought an upgraded tube for the Vali.



That B4 is a blast. I just love the sound signature. I can only hope the Vali sounds half as good with the EH tube.


----------



## iron2k (Jan 3, 2019)

silverfishla said:


> What opamps does the B4X use?  Are they Singles or are they balanced opamps?


This is the description from Aliexpress:
3. The circuit adopts *dual *op amp parallel output, with higher output power.
Tube: USA RAYTHEON JAN5899 ×2
Op amp: NE5532*2 (can be upgraded )   *<--- BTW This is the same Op amp that Burson uses for the new Playmate *


----------



## ColinMacLaren

Is there any point in getting the B4X if I am just going to use it in unbalanced mode?
Is there any chance to keep it running on a charger? I like the idea of a little portable tube amp but if it can only run from battery that s a complete deal breaker for me.


----------



## Lurk650

Has any one switched the tubes out yet on the B4-X? My first tube amp so I'm curious. 

I get some noise in the right ear piece. IEMs more noticeable than full size cans. Occasionally when moving the cable I can get it to go away. Not too bothered about it. Love the sound of this thing, does add some sweet butteryness.


----------



## TheoS53

Got my B4-X today.

Really, REALLY liking this little amp. Looking forward to maybe swapping the opamps


----------



## Onik

TheoS53 said:


> Got my B4-X today.
> 
> Really, REALLY liking this little amp. Looking forward to maybe swapping the opamps


Did ya try it with IEMS??


----------



## triggrhaapi

I just finished my B4-X project. I got my Burson V5i-D op amps today and swapped them in for the NE5532s that are in it as stock. The noise floor is no longer an issue and the full range is definitely sounding better at higher volumes with no distortion. I've been listening to it on my Audio Technica ATH-WS1100is' through an Audioquest cable. I used the stock cable from the headphones to connect my phone to the amp's input, which lets me keep the button and microphone functionality, but moves them down the network a bit. It also lets me keep my LG G7 far enough away from the amp to keep it from making noise due to EM interference. No issues now. I also stuffed a couple semi-tubular sections of polyurethane under the tubes to keep the microphonics to a minimum. It rings much less now while I am walking. I decided not to swap out the tubes for now, since I've gotten the sound to where I wanted it.


----------



## triggrhaapi

Onik said:


> Did ya try it with IEMS??



I would definitely swap out the op amps if you want to use IEMS, I heard the noise floor on 38ohm over the ear cans with the stock op amps.


----------



## Lurk650

triggrhaapi said:


> I just finished my B4-X project. I got my Burson V5i-D op amps today and swapped them in for the NE5532s that are in it as stock. The noise floor is no longer an issue and the full range is definitely sounding better at higher volumes with no distortion. I've been listening to it on my Audio Technica ATH-WS1100is' through an Audioquest cable. I used the stock cable from the headphones to connect my phone to the amp's input, which lets me keep the button and microphone functionality, but moves them down the network a bit. It also lets me keep my LG G7 far enough away from the amp to keep it from making noise due to EM interference. No issues now. I also stuffed a couple semi-tubular sections of polyurethane under the tubes to keep the microphonics to a minimum. It rings much less now while I am walking. I decided not to swap out the tubes for now, since I've gotten the sound to where I wanted it.


so the V5i-D x 2 for $69 from Burson correct?

What is the process to swap them? Never done it before


----------



## triggrhaapi

Lurk650 said:


> so the V5i-D x 2 for $69 from Burson correct?
> 
> What is the process to swap them? Never done it before



Correct. It's relatively simple. The top cover uses 2mm hex screws and the bottom cover uses philips head screws. You only need to remove the screws for the front cover. Once that's off, disconnect the battery. Use a chip puller to remove the chips straight up. I used my tweezers and I bent the pins on the original op amps pretty badly and the second chip came out with quite a lot of force so my little tweezers slipped and sliced my left index finger. Do not do that if you can help it. A chip puller is ideal. I couldn't find one locally but amazon sells them. Order both at the same time to save the headache. Once the old chips are out, orient the op amps so the white dot is facing the upper left corner of the socket (that's pin 1) and simply line up the pins with the socket and press gently and they should just pop in. They are held by friction so they are harder to pull out than push in. By quite a lot. Once they're in, plug the battery back in and replace the front cover and you're done. It's not complex or difficult in the least bit, given the right tools. 

It's not a project until you bleed right? Right?


----------



## rafaelo

triggrhaapi said:


> disconnect the battery.


Is that step nessesarry for the dual b4x amp? For the single b4 amp I changed the opamp without disconnecting the battery.


----------



## triggrhaapi

rafaelo said:


> Is that step nessesarry for the dual b4x amp? For the single b4 amp I changed the opamp without disconnecting the battery.



It's something I've gotten into the habit of doing whenever working on anything electrical or electronic. It's more of a safety measure than anything. I would consider it as necessary as pulling the battery before working on a laptop or pulling out the power cable when working on a PC. It's just prudent. There is also a switch on the B4-X so it's just an extra layer of protection and it takes all of a few moments.


----------



## Onik

How does the balance out sounds compare to normal 3.5mm out?


----------



## triggrhaapi

Onik said:


> How does the balance out sounds compare to normal 3.5mm out?



My headphones don't strictly support it, but my headphone cable has better than normal grounding so it may benefit. I have a 2.5mm balanced to 3.5mm adapter coming from Amazon and I intend to see if it's louder, but Z_Reviews on YouTube says it's louder but not necessarily any clearer. My headphones, Audio Technica WS-1100is', take a 3.5mm input directly on the left side so there's no option for balanced unless I rewire the headphones and I don't have much desire to do that. I'm using an Audioquest Tower cable I got on amazon as a damaged box item for $15 and that alone gave me a hair more clarity and seems to have given a midrange bump versus the stock cable, which has a microphone and start/stop button on it. I have been using that stock cable as a jumper to my phone so I can have an external button to start/stop music while I'm walking outside, and so I can keep the phone a good distance from the amp to avoid noise from the radio transmitters on the phone.


----------



## Lurk650

triggrhaapi said:


> My headphones don't strictly support it, but my headphone cable has better than normal grounding so it may benefit. I have a 2.5mm balanced to 3.5mm adapter coming from Amazon and I intend to see if it's louder, but Z_Reviews on YouTube says it's louder but not necessarily any clearer. My headphones, Audio Technica WS-1100is', take a 3.5mm input directly on the left side so there's no option for balanced unless I rewire the headphones and I don't have much desire to do that. I'm using an Audioquest Tower cable I got on amazon as a damaged box item for $15 and that alone gave me a hair more clarity and seems to have given a midrange bump versus the stock cable, which has a microphone and start/stop button on it. I have been using that stock cable as a jumper to my phone so I can have an external button to start/stop music while I'm walking outside, and so I can keep the phone a good distance from the amp to avoid noise from the radio transmitters on the phone.


You can not add an adapter to the 3.5 and be balanced. You run the risk of damaging your headphones and the Little Bear. With an adapter, you can go from Balanced to Single Ended but never Single to Balanced


----------



## triggrhaapi

Lurk650 said:


> You can not add an adapter to the 3.5 and be balanced. You run the risk of damaging your headphones and the Little Bear. With an adapter, you can go from Balanced to Single Ended but never Single to Balanced



Well yes, once you unify the ground it's unified forever. It was more to see if the balanced output had more oomph to it. I got the adapter and gave it a brief test and it was definitely high pass filtering the right channel for some odd reason (actually it sounded like running ProLogic II on a stereo signal and listening only to a rear channel) so I just decided to stick to 3.5. It's a more robust connector for walking around anyhow. TBH, it's kind of a shame. I would rather have an XLR type connection for walking around, it's far more robust than a dinky little 2.5mm pin.


----------



## Lurk650

triggrhaapi said:


> Well yes, once you unify the ground it's unified forever. It was more to see if the balanced output had more oomph to it. I got the adapter and gave it a brief test and it was definitely high pass filtering the right channel for some odd reason (actually it sounded like running ProLogic II on a stereo signal and listening only to a rear channel) so I just decided to stick to 3.5. It's a more robust connector for walking around anyhow. TBH, it's kind of a shame. I would rather have an XLR type connection for walking around, it's far more robust than a dinky little 2.5mm pin.


What I'm saying is, it will make no difference. The cable itself needs to be balanced in order for balanced to even work.


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## Mouseman

I don't understand why they even sell those adapters - there are too many people out there that have no clue how balanced vs unbalanced works who are quite likely to damage their equipment. There is more power with the balanced output. If I remember correctly, you're getting the opamps running in parallel that way.


----------



## triggrhaapi

Mouseman said:


> I don't understand why they even sell those adapters - there are too many people out there that have no clue how balanced vs unbalanced works who are quite likely to damage their equipment. There is more power with the balanced output. If I remember correctly, you're getting the opamps running in parallel that way.


Are they not running in parallel anyhow?


----------



## Mouseman

triggrhaapi said:


> Are they not running in parallel anyhow?


The B4 only has one opamp, the B4x has two. So I think when you use the B4x in unbalanced mode, you might only be getting one of the two opamps.


----------



## triggrhaapi

Mouseman said:


> The B4 only has one opamp, the B4x has two. So I think when you use the B4x in unbalanced mode, you might only be getting one of the two opamps.



Yes but the architecture of the circuit suggests that both op amps are running. I suppose I could pull one out and see if one channel goes away. The B4 is a totally different circuit design.


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## tichyztech (Apr 10, 2019)

Onik said:


> How does the balance out sounds compare to normal 3.5mm out?



I have both, using them for the past 3 weeks, source is my trusted X5 iii and to be honest there I can't tell the difference in sound. I use M1060s, the DMG and IE80. I listen to all genres. Can anyone else tell the difference?
I always say if you personally can't hear/tell the difference then don't bother wasting your money.


----------



## Grev

Anybody bothered by the spelling mistake?

I thought it was just one but it is the whole batch I think.


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## triggrhaapi

Haha mine too. It made me laugh. I don't mind it.


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## Onik

Grev said:


> Anybody bothered by the spelling mistake?
> 
> I thought it was just one but it is the whole batch I think.


Where is it?


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## Lurk650

LMAO I usually catch those thing. Just checked mine.


----------



## JubilantHD58XOwner

Can I utilize the full potential of these with an HD58X? Zeos says that it needs high impedance, inefficient cans to work properly, but I see a lot of low impedance cans in the thread above. Also, what's the difference between the sound of the B4, B5 and the B1+? The B4 looks the coolest, window and all, and also has modding potential, but is also significantly more expensive than the other two (the B5 is ridiculously cheap on Aliexpress at ~$53)


----------



## triggrhaapi

TheBombaySapphire said:


> Can I utilize the full potential of these with an HD58X? Zeos says that it needs high impedance, inefficient cans to work properly, but I see a lot of low impedance cans in the thread above. Also, what's the difference between the sound of the B4, B5 and the B1+? The B4 looks the coolest, window and all, and also has modding potential, but is also significantly more expensive than the other two (the B5 is ridiculously cheap on Aliexpress at ~$53)



Yes you can use the full potential of these with the HD58X. I would say that you probably won't notice much of the clarity this thing can provide with those headphones unmodded though. I prefer my Audio Technicas to the 58X. I found the 58X muddy and a bit too midrange forward for my tastes. The ATs also are low impedance but they definitely use more power when you want to reproduce sub-bass. I don't have any equipment to measure impedance but I would wager it goes up depending on the strength of the bass signal you're sending. I tend to listen to bassier music, mostly EDM but some hip hop. The 58X is good for rock and roll, but it didn't knock my socks off either. Maybe they need to be modded to really work right. Out of the box they weren't my favorites. I honestly didn't get a whole lot of warmth from the B4X on the HD58X, but they're already pretty warm to begin with. I feel like the Audio Technicas were close and too clinical without an amp and the Little Bear made them warmer and wider and especially with the Burson op amps, they ride the line between clinical and dynamic very very well. You can especially hear the difference on tracks like Fn Pig on Where's the Drop, where the strings and horns swell and crescendo, the tubes clearly add something to classical instruments. 

I haven't modded my 58X Jubilee's but I'm also not planning on keeping them either, since their sub bass in particular is just not what I'm looking for in a pair of headphones.


----------



## JubilantHD58XOwner

triggrhaapi said:


> Yes you can use the full potential of these with the HD58X. I would say that you probably won't notice much of the clarity this thing can provide with those headphones unmodded though. I prefer my Audio Technicas to the 58X. I found the 58X muddy and a bit too midrange forward for my tastes. The ATs also are low impedance but they definitely use more power when you want to reproduce sub-bass. I don't have any equipment to measure impedance but I would wager it goes up depending on the strength of the bass signal you're sending. I tend to listen to bassier music, mostly EDM but some hip hop. The 58X is good for rock and roll, but it didn't knock my socks off either. Maybe they need to be modded to really work right. Out of the box they weren't my favorites. I honestly didn't get a whole lot of warmth from the B4X on the HD58X, but they're already pretty warm to begin with. I feel like the Audio Technicas were close and too clinical without an amp and the Little Bear made them warmer and wider and especially with the Burson op amps, they ride the line between clinical and dynamic very very well. You can especially hear the difference on tracks like Fn Pig on Where's the Drop, where the strings and horns swell and crescendo, the tubes clearly add something to classical instruments.
> 
> I haven't modded my 58X Jubilee's but I'm also not planning on keeping them either, since their sub bass in particular is just not what I'm looking for in a pair of headphones.


I already have the 58X lol, but good to see these will work with those. Do you have the other tube amps I mentioned though? Would you even recommend a tube with the 58X or am I better off with the Fiio Q1 Mk2?


----------



## triggrhaapi

TheBombaySapphire said:


> I already have the 58X lol, but good to see these will work with those. Do you have the other tube amps I mentioned though? Would you even recommend a tube with the 58X or am I better off with the Fiio Q1 Mk2?



No, just the one. I will also say that if you walk a lot and listen to quieter music you will definitely hear the microphonics of these tubes while walking. It doesn't bug me, but it may bug you.


----------



## tichyztech

Onik said:


> Where is it?


Daul. It should be Dual hahaha mine too bought it end of March 2019 from Amazon UK.


----------



## Onik

tichyztech said:


> Daul. It should be Dual hahaha mine too bought it end of March 2019 from Amazon UK.



Been Drinking too much lately so couldn’t figure it out LOL


----------



## fuhransahis

Decided to return my Little Bear B4-x before I received my Burson v5i Dual opamps, so can sell the Bursons to anyone interested once I receive. Can sell for base peice of $69 as listed on their site including PP and shipping, saving the buyer $15 on shipping and you'll have a shorter delivery time within the US. PM if interested!


----------



## Onik (Apr 22, 2019)

I’m thinking to get one b4-x just for IEMS but previously I had issues with very sensitive iems(hissing).

Anyone can recommend me the best and suitable IEMS for B4-X that doesn’t cause any hissing? 

My budget is £100 to £200


----------



## Makiah S

fuhransahis said:


> Decided to return my Little Bear B4-x before I received my Burson v5i Dual opamps, so can sell the Bursons to anyone interested once I receive. Can sell for base peice of $69 as listed on their site including PP and shipping, saving the buyer $15 on shipping and you'll have a shorter delivery time within the US. PM if interested!



May I ask why


----------



## fuhransahis

Mshenay said:


> May I ask why


Bought it for home use as I don't have a dedicated listening spot/room where I can plug in a desktop amplifier to yet. But, turns out I don't have much time to listen at home anyways, so most of my listening is done during my commute. And it's unusable during my commute due to WiFi/cell interference along with vibrations from walking and the train.

Also my IEMs are very sensitive (EE Phantom) and the headphones I tried them with are also very sensitive (iBasso SR1, 22ohm), so too high a noise floor.

Otherwise it sounded nice when I did get to try with the SR1 at home, but didn't use it enough.


----------



## DaYooper

Got the Burson opamps today and immediately installed them in the "daul" mono little bear. What a difference. Makes the DX120 and HP-3 phones sound like units at five times the price, okay maybe I exaggerate a little but I also have the Klipsch amp and it doesn't even come close. I just can't imagine a better sounding deal for less than $200.


----------



## Lurk650

Got the email from Burson, 48hr sale on the V5i opamps. $70 shipped. Just ordered


----------



## cheungtsw

Anyone used the little bear b2 with iem ?


----------



## cheungtsw

How much tube sound I can get from the little bear b5?
I am more interested in the tube sound than the amp portion.  I have the pioneer 30R & UE900s.
If it is on the same level as FX audio tube buffer I would be very happy.


----------



## Lurk650

1st chip came out perfectly with ease. Left chip was a pain and I lost a leg lol. Oh well, new Burson Chips in and the sound is greatly improved IMO. Much more clarity. 

Hex screw size is the 5/64. Wish they used that for the other side since I stripped a screw and had to bend the face plate to get it off then I was able to get the screw out.


----------



## TheoS53




----------



## Joseph Lin

Since I have to stay out of town for business for a few months, without my beloved WA8 made me home sick. Saw this thread two days ago and decides to buy B4-X for experiment. Just got it from Amazon a few hours ago. This thing is really a surprise: small, clean and powerful. It cannot compete with my "transportable" WA8, but very close and it made me wonder why I paid almost 20x more money for WA8. So far, no EM noise yet. The sound is very clean, and powerful. Paired it with my IER-Z1R,  and they are a very good pair. I enjoyed an hour long of listening session. I can bring it for trips without worrying damaging it at all, very happy with the purchase. Thank you all!


----------



## Joseph Lin

I am wondering if anyone replaced the original opamp with Burson V6 Vivid Dual X 2? Will it work? How does it sound like? Any improvement over the original?


----------



## triggrhaapi

Joseph Lin said:


> I am wondering if anyone replaced the original opamp with Burson V6 Vivid Dual X 2? Will it work? How does it sound like? Any improvement over the original?



It's probably possible, but those are a lot taller than the case is wide so you'd have to remove or modify the window to make it work. It's barely taped in there so that won't be terribly difficult to do but it will lose some convenient portability having two op amps jutting out the side. I would imagine it would also have a shorter battery life as they look more powerful. 

I replaced the stock op amps with v5i Duals and I was quite pleased by the upgrade. Plenty for a portable rig.


----------



## Joseph Lin

triggrhaapi said:


> It's probably possible, but those are a lot taller than the case is wide so you'd have to remove or modify the window to make it work. It's barely taped in there so that won't be terribly difficult to do but it will lose some convenient portability having two op amps jutting out the side. I would imagine it would also have a shorter battery life as they look more powerful.
> 
> I replaced the stock op amps with v5i Duals and I was quite pleased by the upgrade. Plenty for a portable rig.



Thank you!


----------



## Hal Rockwell

Did anyone consider trying Nobsound/Douk Audio discrete opamps?


----------



## Joseph Lin (Jun 29, 2019)

I found the solution to the RF interference! Here's what happened:

It drives me crazy when I am listening to a good music. When the RF interference comes in, it spoils everything. I decide to find a solution and surprisingly that there is a very easy solution: The Faraday tape! After taping it over the window, the RFI is gone completely. If it is not enough, two layers of the tape is more than enough. The tape makes the amp ugly though. I do not have time to open the case to find out which part needs to tape over, but I believe it can be done. If you just want to enjoy the music and do not care about the look, this is a quick and good solution you can try. Otherwise, open the case and spend an hour and find out the offending parts and share it with us. You can find the tape on Amazon, it is very cheap. Enjoy the noiseless B4X!


----------



## Fickle-Friend

Joseph Lin said:


> I found the solution to the RF interference! Here's what happened:
> 
> It drives me crazy when I am listening to a good music. When the RF interference comes in, it spoils everything. I decide to find a solution and surprisingly that there is a very easy solution: The Faraday tape! After taping it over the window, the RFI is gone completely. If it is not enough, two layers of the tape is more than enough. The tape makes the amp ugly though. I do not have time to open the case to find out which part needs to tape over, but I believe it can be done. If you just want to enjoy the music and do not care about the look, this is a quick and good solution you can try. Otherwise, open the case and spend an hour and find out the offending parts and share it with us. You can find the tape on Amazon, it is very cheap. Enjoy the noiseless B4X!



Hi where exactly did you put the tape? Any pics? Thanks


----------



## Joseph Lin

Fickle-Friend said:


> Hi where exactly did you put the tape? Any pics? Thanks


I just tape over the window, no need for a picture.


----------



## Joseph Lin

I have been listening to it with Faraday tape over the clear window for a few days. I pair it with Sony IER-1ZR, the sound is incredibly awesome, almost the same as WooAudio WA8. I am thinking of selling WA8 now. 1/20's the cost and the difference is not much! Especially the bass with IER-1ZR is like unreal for a portable setup!


----------



## Fickle-Friend

Hi how long is the burn in for the 4X?


----------



## Fickle-Friend

where can I buy op amps for this in the UK please?


----------



## Lurk650

Selling my B4-X with V5i mod

https://www.head-fi.org/threads/little-bear-b4-x-burson-v5i-opamps.911333/


----------



## Hal Rockwell

Found these TRULIS opamps being sold on Penon audio, but didn't find any more info about those. Does anyone know what they are and do they worth getting?


----------



## Ult1mat3X

So the amp arrived today in the mail which took allmost 4 week shipping. and my first impressions werent great the little bear has a a horid pot and when ever you touch the thing it makes noise but as long as you dont change volume much during a song its fine. The sq at first was pretty murky and warmed up a little later (burn in/the tubes warming up) but all in all the sq isnt anything special. Now the build quality isnt amazing but it works, the tube heats up so much the whole amp feels like it will melt after like an hour or so. If you want a fun toy to mod this will be nice if you want a tube amp to listen to music with and have it sound a amazing go find a TTVJ portable hybrid tube amp.


----------



## triggrhaapi

Ult1mat3X said:


> So the amp arrived today in the mail which took allmost 4 week shipping. and my first impressions werent great the little bear has a a horid pot and when ever you touch the thing it makes noise but as long as you dont change volume much during a song its fine. The sq at first was pretty murky and warmed up a little later (burn in/the tubes warming up) but all in all the sq isnt anything special. Now the build quality isnt amazing but it works, the tube heats up so much the whole amp feels like it will melt after like an hour or so. If you want a fun toy to mod this will be nice if you want a tube amp to listen to music with and have it sound a amazing go find a TTVJ portable hybrid tube amp.



My experience is nothing like any of this. The amp gets a little warm yes but it's not even uncomfortable to touch during operation, just warm. I have had zero issues from the volume pot, experience nothing approaching burn in adjustments after tons of hours of listening. It did sound better with the Burson op amps installed but it wasn't bad at all with the stock op amps. Maybe contact the company and see about a repair, it sounds like you got a bad unit.


----------



## Mouseman

Yeah, same thing here. I've played it for hours and it gets nothing more than slightly warm. Are you sure it's the volume pot and not bumping the unit and getting microphonics? Although it takes more shaking than I expected to get any pinging.

It does sound like you got a lemon.

Burson sent me an email this morning, they have a 20% off sale on all opamps. It'd be a good time to pick one (or two if you have the balanced version like I do) -- I think it's a good update.


----------



## silverfishla

Ult1mat3X said:


> So the amp arrived today in the mail which took allmost 4 week shipping. and my first impressions werent great the little bear has a a horid pot and when ever you touch the thing it makes noise but as long as you dont change volume much during a song its fine. The sq at first was pretty murky and warmed up a little later (burn in/the tubes warming up) but all in all the sq isnt anything special. Now the build quality isnt amazing but it works, the tube heats up so much the whole amp feels like it will melt after like an hour or so. If you want a fun toy to mod this will be nice if you want a tube amp to listen to music with and have it sound a amazing go find a TTVJ portable hybrid tube amp.


Maybe your trim pots are turned up too high?


----------



## allaces305 (Aug 7, 2019)

Can you send a balanced signal using the 2.5mm out of the es100 Bluetooth adapter into the 3.5mm input of the little Bear B4-X assuming you get the proper cable???? If yes then where can you find a cable that is male 2.5mm to male 3.5mm??? I'm looking to go fully balanced all the way from the source all the way to the iem using the little bears balanced out... Thank you for any help in advance.


----------



## Mouseman

allaces305 said:


> Can you send a balanced signal using the 2.5mm out of the es100 Bluetooth adapter into the 3.5mm input of the little Bear B4-X assuming you get the proper cable???? If yes then where can you find a cable that is male 2.5mm to male 3.5mm??? I'm looking to go fully balanced all the way from the source all the way to the iem using the little bears balanced out... Thank you for any help in advance.


The input of the Little Bear isn't balanced, so once you convert from the ES100, you're no longer balanced. There aren't a whole lot of fully balanced DACs and amps that I've seen, and all are quite a bit more than the LB.


----------



## iccp

Hi people (sorry for my rusty english, writing form spain), Anybody have change the battery for another with more capacity that fits on the space of the unit that have? (gretting links to batteries suitable to replace with more capacity), 

Also, related to microphonics, also anybodoy has fill the inside of the case, or outside) with copper film or anything to avoid microphonics, and could post any picture of the result (to imaging the process if is not described)

I want a more battery capacity due to the dual burson install, and almost 4 hours is so low time to me to charge. Also I have read that someone have bridged the batery to have directo power suply to the unit (making no portable) but with more juice of the sound and burson capabilities.

Thanks in advace for all the stuff that you could post. So interested in improve batterie or if not, make in direct supply. Aslo perform a futher isolation of the unit despite I haven´t so evident problem cause I usually attached with my mojo and iphone, using between a carbon fiber of 3mm plate (so recomendable, and works well in movement the micropohincs barely doesn´t affect, with isolate both, but i bet that many people will also interested in this 2 topics to perform the little bear b4-x, the mini marvelous (I´m also in looking for another so best portable valve unit, discarting wa8 for the price an to me, not so good valve signature.

Also I have heard so good words of another mini valve good amp, called LOXJIE P20, but this is stationary, no portable, and the inputs from my mojo, hugo 2 or ifi pro cam, need more balance and at least good quality cable, and this is more complicated to manage than the little bear to lay on bed with the mojo or hugo and enjoy music with no complex preparatives

Thanks in advance again

PS: so recommeded burn in the little bear at least to me, 50 hours, until beguin to give more clear juice. WIth new opamp, also a burn in is needed (comparing sound just installed, and after, as new and after with the burson


----------



## Mouseman

iccp said:


> Hi people (sorry for my rusty english, writing form spain), Anybody have change the battery for another with more capacity that fits on the space of the unit that have? (gretting links to batteries suitable to replace with more capacity),
> 
> Also, related to microphonics, also anybodoy has fill the inside of the case, or outside) with copper film or anything to avoid microphonics, and could post any picture of the result (to imaging the process if is not described)
> 
> ...


I have some copper foil that I'm going to add, but when I opened it up I was in such a hurry to put the Bursons in that I didn't get to it. When I get around to it, I'll post the pics. I think that I'll need to leave at least part of the window uncovered (despite the risk that EM might leak in) so I can see that it's turned on and the tubes are illuminated. I know that they are backlit, but I have to be able to tell that it's turned on without checking the volume pot.


----------



## iccp

This is what I have done so far to improve the b4-x, with copper foil as a "faraday cage", to EM, despite the window, and the burson V5i


----------



## Joseph Lin

iccp said:


> This is what I have done so far to improve the b4-x, with copper foil as a "faraday cage", to EM, despite the window, and the burson V5i


does it work? from my experience, unless window is covered, RFI still affecting it.


----------



## tjw321

IANAE, but I think you need a 1cm mesh to be really effective against cell phone signals. So this should be fairly good, but to get more RFI attenuation without completely obscuring the window you can probably just add a few thin strips across the window about 1cm apart. But, as I said, IANAE!


----------



## terminusx

Is the b4-x better than the b4? I have the b4 and I was thinking if I made the right choice because the price difference is almost 40%.


----------



## fabien32 (Sep 10, 2019)

JennaFF said:


> 6021 from Thomson-CSF



i switch the omp on my b4 to muses02 ($9 on aliexpress) and also the distortion at high volumes has gone, and it sound amazing (with all my DAXCs).
i wonder what would i get if i replaced the tube ?


----------



## iccp

fabien32 said:


> i switch the omp on my b4 to muses02 ($9 on aliexpress) and also the distortion at high volumes has gone, and it sound amazing (with all my DAXCs).
> i wonder what would i get if i replaced the tube ?



Yeah, it´s possible tube rolling for anyone that perform better? which one? supposed to soldering easy and all the stuff...


----------



## Meanstreak242

My B4-X has a channel imbalance.   The left channel is definitely louder than the right channel.   (I'm using it single ended out.  Tried multiple cables and multiple sources.)   Can this be fixed or do I have a defective unit?  (I originally planned on swapping out the opamps for the Burson, but I'd rather not sink money into a unit that's not working right.)   Should I return it or can I just fix this myself?


----------



## fabien32 (Sep 12, 2019)

Meanstreak242 said:


> My B4-X has a channel imbalance.   The left channel is definitely louder than the right channel.   (I'm using it single ended out.  Tried multiple cables and multiple sources.)   Can this be fixed or do I have a defective unit?  (I originally planned on swapping out the opamps for the Burson, but I'd rather not sink money into a unit that's not working right.)   Should I return it or can I just fix this myself?


There is inside the unit screws for each channel that you can adjust with them the volume ect


----------



## Mouseman

Agree 100%. With the stock unit I couldn't tell there was an imbalance. Once I did the Burson upgrade, I could tell they were off. I adjusted it a slight bit with the screw and it's now dead on.


----------



## Yobster69

Meanstreak242 said:


> My B4-X has a channel imbalance.   The left channel is definitely louder than the right channel.   (I'm using it single ended out.  Tried multiple cables and multiple sources.)   Can this be fixed or do I have a defective unit?  (I originally planned on swapping out the opamps for the Burson, but I'd rather not sink money into a unit that's not working right.)   Should I return it or can I just fix this myself?


As mentioned above, you can adjust this with the little pots on the circuit board, but a word of advise.... take a picture of the board first, a nice close up so you can see how they are set now, just in case you adjust any and do not like the outcome, you can then at least re set them how they were. 
Good luck sorting it


----------



## Meanstreak242

Stock opamps it was definitely off.   Everything was shifted to the left.  It's now fixed however.  (Am I correct in assuming the pots on the outside are for opamp gain, and the inner pots are for for tube bias?)  I am going to reserve judgement on this until I hear the Burson opamps.


----------



## choisan (Sep 21, 2019)

how is the difference with b4-x and alo cdm? almost the same circuit? RF noise level? my unbalanced version has a lot of interference when it was placed close to my mobile phone


----------



## triggrhaapi

Not the same circuit, Alo uses different tubes. I'm not sure what op amps they use either. However, modding a B4-x is outrageously cheaper than buying a stock Alo so there's that. RF interference is from the tubes, which are very RF sensitive. I have opted to put the amp in a different pocket, which requires a long jumper but solves the issue. The near field RF of a cell phone is insanely strong.


----------



## Hal Rockwell

Finally got to moding my B4. The goal was to be able to install any opamp and still keep the lid on. It ceased being portable, but it's still transportable, which is what I need - being able to take it to any part of the house and enjoy my music collection.



 

 

 

 

 

P.S.
The static is largely affected by the type of opamp being used. Some of which I tried make the static almost inaudible, even with the phone right next to it.


----------



## fabien32

Hal Rockwell said:


> Finally got to moding my B4. The goal was to be able to install any opamp and still keep the lid on. It ceased being portable, but it's still transportable, which is what I need - being able to take it to any part of the house and enjoy my music collection.
> 
> 
> 
> ...


is the opamp being used is PCS SA-200?


----------



## Hal Rockwell

fabien32 said:


> is the opamp being used is PCS SA-200?



SparkoS


----------



## fabien32

Hal Rockwell said:


> SparkoS


and what can you say about the sound? (i have a feeling PCS SA-200 is really amazing )


----------



## LaughMoreDaily

terminusx said:


> Is the b4-x better than the b4? I have the b4 and I was thinking if I made the right choice because the price difference is almost 40%.


I'm curious as well. Good question.


----------



## Hal Rockwell

fabien32 said:


> and what can you say about the sound? (i have a feeling PCS SA-200 is really amazing )



I spent just a couple of minutes listening to it, but right off the bat, I can say that I found it a bit treble aggressive for my taste, and a little hollow in the mids.


----------



## fabien32

LaughMoreDaily said:


> I'm curious as well. Good question.


It is a little bit better specially if you have balanced headphones, but the upgrade of the omps is doubled


----------



## maxcaovn

Mine B4X also experiencing channel imbalance. But after 10mins playing, it balanced again.


----------



## Grindcore77 (Sep 28, 2019)

Hey guys just stumbled on this thread...have one of these and replaced the op's would one go further? Anyone messed with caps/resistors? Also tube rolling...seems a bit of a pain because of the soldering...surely a mod to get a couple of 8 pin tube holders in there lol


----------



## Grindcore77

http://mhdtlab.com/socket.htm


----------



## Grindcore77

And maybe a better battery pack? That could fit straight in?


----------



## fabien32

i recived my PCS SA-200 and it is really amazing OMG!


----------



## Onik

fabien32 said:


> i recived my PCS SA-200 and it is really amazing OMG!



Never heard of this op amp, but seems to me that it's Chinese made and a clone of Sparkos SS3602.


----------



## fabien32

Onik said:


> a clone of Sparkos SS3602


 don't think it's a clone, it actually sound way better (to me) than the Sparkos. check this out 
https://www.ebay.com/itm/Douk-Audio...var=573724434127&_trksid=p2057872.m2749.l2649


----------



## Hal Rockwell

fabien32 said:


> don't think it's a clone, it actually sound way better (to me) than the Sparkos. check this out
> https://www.ebay.com/itm/Douk-Audio-HiFi-SA200-Fully-Discrete-Dual-Op-Amp-Module-Replace-MUSES02-SS3602/273892617949?ssPageName=STRK:MEBIDX:IT&var=573724434127&_trksid=p2057872.m2749.l2649



Definitely not cheap for for Chinese discreet opamp.


----------



## fabien32

Hal Rockwell said:


> not cheap


i had a good feeling about this one, and it paid of big time


----------



## Joseph Lin

fabien32 said:


> don't think it's a clone, it actually sound way better (to me) than the Sparkos. check this out
> https://www.ebay.com/itm/Douk-Audio-HiFi-SA200-Fully-Discrete-Dual-Op-Amp-Module-Replace-MUSES02-SS3602/273892617949?ssPageName=STRK:MEBIDX:IT&var=573724434127&_trksid=p2057872.m2749.l2649


How's hissing?


----------



## fabien32 (Oct 19, 2019)

Joseph Lin said:


> How's hissing?


none that i can hear, but i have good headphones and good DACs. the sound that come out is amazing especially with the T1 4497. the only problem with it is the battery drain after less than two hours! so now i have to replace the battery pak


----------



## fabien32 (Oct 21, 2019)

Joseph Lin said:


> How's hissing?


i just played hifi files via Tidal with my k20 pro (great sound card)witch i connected to a nx4, then to little dot3 ((with upgraded tubes) and then to my upgraded little bear, connected to Sennheiser HD 650! OMG!!! with the HyperX Cloud Alpha it is even better !


----------



## fabien32

maxcaovn said:


> But after 10mins playing, it balanced again


I have a b4 and it balanced after 30 minutes  but with all the upgrades it sounds amazing


----------



## Grindcore77 (Nov 20, 2019)

Hey all in the process of modding mine..went the miniature socket route so rolling tubes wont be such a PITA..

Waiting on some more parts to finish up.got some sylvanias in at the moment...


----------



## ledzep

Anyone had a play with the b4x, thinking of having a modding session with it.


----------



## Hal Rockwell

fabien32 said:


> i recived my PCS SA-200 and it is really amazing OMG!



Did you grounded it with the ground wire it comes with?


----------



## Grindcore77

Guys..when adjusting the pots they do or dont have to be done equally? I am getting better results when they are postioned independtly of each other lol....


----------



## fabien32

Hal Rockwell said:


> Did you grounded it with the ground wire it comes with?


no i didn't (when i tried i got some noises)


----------



## Onik (Dec 4, 2019)

This is what I received! 
My B4-X looks different? Is it a clone?


----------



## Mouseman

Grindcore77 said:


> Guys..when adjusting the pots they do or dont have to be done equally? I am getting better results when they are postioned independtly of each other lol....


They don't have to be done equally. I had a small amount of imbalance when I replaced the opamps -- it's not huge, but they weren't the same.


----------



## Hal Rockwell

fabien32 said:


> no i didn't (when i tried i got some noises)



I can't seem to get the SA-200 to work in my B4. Only one channel is working at any given time - either right or left. Works fine with my FiiO E12DIY though.


----------



## Onik

HELLOOOOO!!! Is this CLONE OR REAL??


----------



## fabien32

Hal Rockwell said:


> I can't seem to get the SA-200 to work in my B4. Only one channel is working at any given time - either right or left. Works fine with my FiiO E12DIY though.


I had a similar problem when the battery was weak. i replaced the battery and it is amazing


----------



## Hal Rockwell

fabien32 said:


> I had a similar problem when the battery was weak. i replaced the battery and it is amazing



Did you mean "charged" or completely replaced with a new one?


----------



## fabien32

change completely, but first i charged. It finished the battery after an hour and a half, so i had to upgrade the battery


----------



## fabien32 (Dec 10, 2019)

Hal Rockwell said:


> Did you mean "charged" or completely replaced with a new one?


 it's not a simple fix, first you need to make sure you don't reverse the polarities, then you can charge it only for one hour and 15minute on 24v(doesn't charge with original charger) and last you need to lower the volume and use some other amplifier as a preamp (i use the NX4)


----------



## Hal Rockwell

fabien32 said:


> it's not a simple fix, first you need to make sure you don't reverse the polarities, then you can charge it only for one hour and 15minute on 24v(doesn't charge with original charger) and last you need to lower the volume and use some other amplifier as a preamp (i use the NX4)



I decided to make the B4 completely stationary, by taking out the battery, and using a MEANWELL 12V 2A power supply.


----------



## fabien32

Hal Rockwell said:


> I decided to make the B4 completely stationary, by taking out the battery, and using a MEANWELL 12V 2A power supply.


 And what can you say about it? Where did you buy it? And how did you do it exactly? If you may?


----------



## Hal Rockwell (Dec 11, 2019)

fabien32 said:


> And what can you say about it? Where did you buy it? And how did you do it exactly? If you may?



I just ordered the components from ebay. I'll post some photos when it's done.


----------



## bogginhead

Onik said:


> HELLOOOOO!!! Is this CLONE OR REAL??


Looks real as far as I can tell, man.


----------



## Onik

bogginhead said:


> Looks real as far as I can tell, man.



at last someone..


----------



## maxcaovn

If you are not careful when adjusting the resistors, the sound will be messed up with heavy distortion. 
This amp more recommend for earbuds not IEMs.


----------



## katatonicone1

fabien32 said:


> i switch the omp on my b4 to muses02 ($9 on aliexpress) and also the distortion at high volumes has gone, and it sound amazing (with all my DAXCs).
> i wonder what would i get if i replaced the tube ?


How is your muses02 experience after this time? Do you use b4 with IEMs by any chance?


----------



## katatonicone1

Two bursons for b4x seem expensive. Anything else you guys could recommend?


----------



## Lucamusic81

Amp not tube, Aune b1s


----------



## fabien32

katatonicone1 said:


> How is your muses02 experience after this time? Do you use b4 with IEMs by any chance?


I love it but i am always alternating with other one as well


----------



## KuroYariman (Apr 9, 2020)

Hey just received a b4-x from amazon! Sounds good for the most part there’s a bit of noise on my  echobox finders but can’t judge anything yet just wanted to provide as much info as possible.
anyways the reason for this post is the b4-x is emitting a horrible smell! Possibly ozone!
I don’t know why but it’s bad! I’m new to tubes so I did some quick research and couldn’t find anything truly helpful.
Except the possibility of red-walling which is a term from some guitar amp people. So one of the tubes is glowing much brighter than the other but that shouldn’t be a problem with new tubes. Maybe damage from shipping?

I’m hoping that it just needs some adjustments but I don’t have the knowledge for that. I intend for this to be a bit of a project amp so if I have to learn some stuff to fix it that’s fine by me.
let me know what you think!



As you can see the left side is brighter!
Edit: I tried again right after posting this and noticed the ringing from the tubes only comes through the right channel suggesting it is that left tube! I have no idea if the right and left channels are actually the right and left tubes but it would make sense! Not that chi-fi products always make sense!


----------



## maxcaovn

This amp


KuroYariman said:


> Hey just received a b4-x from amazon! Sounds good for the most part there’s a bit of noise on my  echobox finders but can’t judge anything yet just wanted to provide as much info as possible.
> anyways the reason for this post is the b4-x is emitting a horrible smell! Possibly ozone!
> I don’t know why but it’s bad! I’m new to tubes so I did some quick research and couldn’t find anything truly helpful.
> Except the possibility of red-walling which is a term from some guitar amp people. So one of the tubes is glowing much brighter than the other but that shouldn’t be a problem with new tubes. Maybe damage from shipping?
> ...


This amp really does need some tuning and once you play around with the 4 resistors (if you don't know what you are doing like me), it nearly impossible to get it right. The seller advised me to play around with the transitor to counter  channel imbalance then it really difficult to get the right balance. Sitting in the drawer eversince. 
However, some people really upgraded this with lots of things like new tube, new power supply capacicators, new opamp.


----------



## katatonicone1

KuroYariman said:


> Hey just received a b4-x from amazon! Sounds good for the most part there’s a bit of noise on my  echobox finders but can’t judge anything yet just wanted to provide as much info as possible.
> anyways the reason for this post is the b4-x is emitting a horrible smell! Possibly ozone!
> I don’t know why but it’s bad! I’m new to tubes so I did some quick research and couldn’t find anything truly helpful.
> Except the possibility of red-walling which is a term from some guitar amp people. So one of the tubes is glowing much brighter than the other but that shouldn’t be a problem with new tubes. Maybe damage from shipping?
> ...


I have no idea what is the problem, but I can write about my experience. I've got my b4-x for less than a month now, and definitely there is no smell. The lamps most likely shine the same way, though there are written markings on the lamps and they cover the lamps in different positions so it is impossible to tell for sure. There is no channel imbalance in my unit, even after changing opamps to Muses 8820 from official sales channel.  There is ringing in left channel after the chasis contacts other object, so I would not worry about it.


----------



## KuroYariman

Thanks for getting back to me! I really have no idea if the brightness of the tube is an issue or not it could just be chance. I am aware that the tube ringing is normal but thought it was odd that it was only one channel. Really wish I had a balanced cable to test. Damn Drop shipping goin on a month now. 
anyways I already contacted the seller theythought it was odd too and suggested I get a replacement from amazon. Thank god for prime. I’ll probably keep it a couple days too see what happens.
Are we limited to the 4 or so different opamps the company suggests?  
I’m curious about tubes too so if anyone out there knows anything let me know!


----------



## Hal Rockwell

KuroYariman said:


> Thanks for getting back to me! I really have no idea if the brightness of the tube is an issue or not it could just be chance. I am aware that the tube ringing is normal but thought it was odd that it was only one channel. Really wish I had a balanced cable to test. Damn Drop shipping goin on a month now.
> anyways I already contacted the seller theythought it was odd too and suggested I get a replacement from amazon. Thank god for prime. I’ll probably keep it a couple days too see what happens.
> Are we limited to the 4 or so different opamps the company suggests?
> I’m curious about tubes too so if anyone out there knows anything let me know!



You're not limited to the four opamps the manufacturer suggests. As long as the new amp has the same pinout as the original, it's safe to use.


----------



## wavid

katatonicone1 said:


> Two bursons for b4x seem expensive. Anything else you guys could recommend?


For this reason I am thinking of getting the b4 instead as it will only need 1 opamp upgrade
Is that a better option for someone that does not plan on using any balanced headphones?
Also the b4 is £20 cheaper ($25)


----------



## Hal Rockwell

wavid said:


> For this reason I am thinking of getting the b4 instead as it will only need 1 opamp upgrade
> Is that a better option for someone that does not plan on using any balanced headphones?
> Also the b4 is £20 cheaper ($25)



It's a better option altogether. B4X is only has like 5% more power than B4, and B4X has the same single ended input as the B4. So, it makes no sense going for B4X. Save your money.


----------



## der luda

As a joy at my hobby, I also bought the B4 X.

In addition 2 x Supreme Sound Opamp V5i - Dual Copper tape and small parts.
Machined cables, connections, insulated, tube lined and then burn in for a few hours.

Tested the first test today with a Sony XBA N3AP ... yes, I'm surprised, far better than expected.
I will install a higher quality battery, then I can run a small, fine DAP in combination with my old Samsung S8.

....something like that is fun


----------



## wavid

Thanks for the tip, I went for the B4. 
I have been listening to it on my HD650s and its awesome!
I will probably eventually stick a v5i in it but for now what are some cheaper recomended opamps I can try out? (under £15)
Id like to get a few just to play around with, see if i can hear a difference etc.
Are opamps better bought from proper stores like Mouser etc or are the ones on Aliexpress/ebay fine? 
Id like a opa1612 but it does not come as DIP8 unless I buy from Aliexpress/ebay.
I assume it would not be easy to convert myself?
Although I just bought a soldering iron to start my DIY journey (Starting with a CMoy), if its something I can do myself it might be a good learning step.


----------



## Hal Rockwell

wavid said:


> Thanks for the tip, I went for the B4.
> I have been listening to it on my HD650s and its awesome!
> I will probably eventually stick a v5i in it but for now what are some cheaper recomended opamps I can try out? (under £15)
> Id like to get a few just to play around with, see if i can hear a difference etc.
> ...



I do not recommend buying any opamps on ebay or aliexpress. They are known sources of counterfeit opamps. If a dip8 opa1612 exists only on those selling platforms, it's probably a fake. Use only mouser or digikey! - it's more expensive, but at least you get what you pay for.


----------



## der luda (May 21, 2020)

Now bx 4 is ready, 2 x Burson V5i installed.
All solder joints checked, the circuit board, tube insulated with polyimide.
Battery, housing insulated with copper.
No noise caused by LTE / WiFi 

Directly on the Galaxy S8, I have now burned in a few days with the Hifiman Edition S (current around 149.-).
This is an interesting combination, sounds pretty good, I'm not sure yet ...
It is probably so much fun because it was made by myself


----------



## Whitigir

Grindcore77 said:


> Hey all in the process of modding mine..went the miniature socket route so rolling tubes wont be such a PITA..
> 
> Waiting on some more parts to finish up.got some sylvanias in at the moment...



Does none know where to buy these sockets


----------



## ledzep

Whitigir said:


> Does none know where to buy these sockets


Try mouser Rs or digikey


----------



## Whitigir

And have any one been tube rolling ? What kind of tubes will be a replacement for it ?


----------



## fabien32

Whitigir said:


> Does none know where to buy these sockets


I think it is custom made, not for the public


----------



## Joseph Lin

Grindcore77 said:


> Hey all in the process of modding mine..went the miniature socket route so rolling tubes wont be such a PITA..
> 
> Waiting on some more parts to finish up.got some sylvanias in at the moment...


Where did you get those green rings around tube? Does it reduce the ringing?


----------



## kakaworu

Joseph Lin said:


> Where did you get those green rings around tube? Does it reduce the ringing?



They look like castration bands for goats.


----------



## Inju

I just wanted to say. I just picked one of these up and it's fantastic. Definitely gives me a tube sound but is very dependent on my source. Using my Note 10 Lite headphone out it is noisy and buzzez and beeps.  Using my Alienware M17 headphone out it is noise free and very, very clean. I'm pairing this with the Fiio BTR3K which I just ordered and will report back in. I'm liking this more then my Little Dot MK 3 I've had for 8 years.


----------



## fabien32

Inju said:


> but is very dependent


But of course, if the source is  crappy you amplify crap


----------



## Joseph Lin

Inju said:


> I just wanted to say. I just picked one of these up and it's fantastic. Definitely gives me a tube sound but is very dependent on my source. Using my Note 10 Lite headphone out it is noisy and buzzez and beeps.  Using my Alienware M17 headphone out it is noise free and very, very clean. I'm pairing this with the Fiio BTR3K which I just ordered and will report back in. I'm liking this more then my Little Dot MK 3 I've had for 8 years.


Yeah, cell phones have strong Magnetic interference and B4 is weak in blocking interference so..


----------



## Inju

With the Fiio BTR3K I'm in love. The Little Bear is very warm with my HiFi-Man HE-4XX streaming APTX. The magnetic/electronic shielding is horrible on these and if it's close to my phone it will buzz. Thus the bluetooth amp/dac module combo.  The rubber bands that come with the Little Bear are perfect for the clip on the Fiio BTR3K. I'll get my HD6XX and report later as well.


----------



## Inju

Oh just as an aside my Note 10 Lite streams LDAC! My Alienware M17 does APTX. I love how the BTR3K changes color and lets me know.


----------



## Onik (Aug 1, 2020)

The B4-X SUCKS imo, because I experienced slight hiss from every high end Headphones I ever tried from Hd650/ATH-R70X to BEYERDYNAMIC T1( 600 ohm), I miss the Old Original B4 which was my favourite the X labelled for balanced out LOL tried my HD650 with balanced cable still experienced slight hiss, this amp was very badly engineered, a portable tube amp should have have pitch black background when using high impedance cans!

Also when it comes to balanced out it doesn't make any sense because you are using single ended inputs and no balanced inputs which could make lot of sense just like Loxjie P20!(balanced in balanced out)

Now I'm thinking to sell this trash and buy the original B4 again.!


----------



## Inju

Mine are dead silent. Just tried them with my HD6XX and it's fantastic for me. I have no hiss and really love this combo! For $99 a no brainier for me. I love this hobby and just kicking back listening to music.


----------



## Onik

Inju said:


> Mine are dead silent. Just tried them with my HD6XX and it's fantastic for me. I have no hiss and really love this combo! For $99 a no brainier for me. I love this hobby and just kicking back listening to music.



Be in a real quite room, and then plug your hd6xx slowly in and out and let me know if you hear slight hiss, if you can't then maybe your B4 X is better than mine. You know it's a Chinese trash so it's never perfect, probably my ones has build quality issues that's what causing the hiss. but Fxxx it I'm gonna sell it and buy the B4.


----------



## fabien32

Onik said:


> Be in a real quite room, and then plug your hd6xx slowly in and out and let me know if you hear slight hiss, if you can't then maybe your B4 X is better than mine. You know it's a Chinese trash so it's never perfect, probably my ones has build quality issues that's what causing the hiss. but Fxxx it I'm gonna sell it and buy the B4.


When you open the case you can find on each side of the tubes a orange screw, if you turn it a little bit to the right or to the left, it might fix it


----------



## Onik

fabien32 said:


> When you open the case you can find on each side of the tubes a orange screw, if you turn it a little bit to the right or to the left, it might fix it



You mean this two?


----------



## fabien32 (Aug 5, 2020)

Look closer, there's two from each side


----------



## KittySneeze

Inju said:


> With the Fiio BTR3K I'm in love. The Little Bear is very warm with my HiFi-Man HE-4XX streaming APTX. The magnetic/electronic shielding is horrible on these and if it's close to my phone it will buzz. Thus the bluetooth amp/dac module combo.  The rubber bands that come with the Little Bear are perfect for the clip on the Fiio BTR3K. I'll get my HD6XX and report later as well.



You just gave me the idea to do this with my BTR5, but realized they both will have volume control. How do you set your volume?

I assume max volume on your source, but specifically what do you set the BtR3K volume to?


----------



## Inju

Onik said:


> Be in a real quite room, and then plug your hd6xx slowly in and out and let me know if you hear slight hiss, if you can't then maybe your B4 X is better than mine. You know it's a Chinese trash so it's never perfect, probably my ones has build quality issues that's what causing the hiss. but Fxxx it I'm gonna sell it and buy the B4.



I'm not understanding, you want me to plug the headphones in and out and see if there is the slight hiss while doing this? Do you mean the slight ping? This is normal for headphone tube amps if you knock the case there is a slight ping. Mine is absolutely perfect. Now deciding if I should build a Crack or buy a Dark Voice.....decisions, decisions.  I just built several modules for fun the last three weeks so likely going to get the Crack!


----------



## Inju

der luda said:


> Now bx 4 is ready, 2 x Burson V5i installed.
> All solder joints checked, the circuit board, tube insulated with polyimide.
> Battery, housing insulated with copper.
> No noise caused by LTE / WiFi
> ...



Regarding this shielding, does it work? The biggest offender is going to be the clear window, which I believe is acrylic. I did explore if I could find a transparent conductive window and the closest thing I could find was this guy: Click Here

I believe non grounded Faraday Cage shielding also may be more effective with holes? Not sure exactly how that works though.  https://forum.allaboutcircuits.com/threads/holes-in-a-faraday-cage.69512/


----------



## Inju (Aug 17, 2020)

KittySneeze said:


> You just gave me the idea to do this with my BTR5, but realized they both will have volume control. How do you set your volume?
> 
> I assume max volume on your source, but specifically what do you set the BtR3K volume to?



I actually max out the BTR3K and adjust using the tube amp. I think the noise on the BTR5 will be much lower then the Tube amp and thus don't need to drive the tube amp as much, however, if you want more Tube distortion, then do it the other way around. The harmonic distortions caused by the tubes are pleasant and give it a "vintage-like" sound that you might find more pleasant. One tip as well, attach the BTR BEHIND the unit away from the plastic shield. There is now NO noise for me doing that.


----------



## Celamojo

I had a Nobsounds NS-08 once.  It was quite a strange experience as it sometimes sounds very musical and sometime just full of noise and disengaging.  I couldn't figure what was going on and had to sell it


----------



## Celamojo

It was with some replacement vacuum tubes from GE and MAZDA so tubes should not be the issue there.


----------



## Barndoor

My little dot has developed noise as well.
Decided to try a B4 as transportable is now my preferred route rather than a fixed location desktop device.
Will swap the opamp for the Burson I'm currently using in the little dot.

I Did find a few other items on Ali Express
GAD HIFI ADIII
Oriolus BA300S ii
Laidys
HIFI fever

Anyone have any thoughts on any of these?

Thinking outside the box a bit I was wondering whether it would be possible to run a 12v DC amp from a battery source, such as:
AIYIMA T5 6K4 from this battery
Would this work?


----------



## seamon

Barndoor said:


> My little dot has developed noise as well.
> Decided to try a B4 as transportable is now my preferred route rather than a fixed location desktop device.
> Will swap the opamp for the Burson I'm currently using in the little dot.
> 
> ...


Can vouch for BA300s. Superb sounding unit!


----------



## Barndoor

My Little Bear B4 arrived yesterday.
Pleased to report hardly any hiss with Stellia. What there is is barely noticeable when no music is playing.
There is a pop when the device is turned on.

Feeding from my Cowon P1.
Stock it is ok, better than I expected, but definitely a significant downgrade in sound with it in the chain.

Removed the lid, popped out the window and inserted the tall Burson v5 (I don't have the smaller v5i).
Now much better and is no longer sounding like a downgrade.

Need to spend a lot more time comparing before coming to a final verdict on it, however without the opamp change I suspect it would have gone in a draw never to be used again pretty quickly.


----------



## fabien32 (Sep 12, 2020)

As far as I know the v5 is not the correct one( I think it will cause it to  be mono)


----------



## Barndoor

fabien32 said:


> As far as I know the v5 is not the correct one( I think it will cause it to  be mono)


V5 comes in single and dual. Mine is dual and definitely not mono.


----------



## LaughMoreDaily (Sep 12, 2020)

Barndoor said:


> My Little Bear B4 arrived yesterday.
> 
> Removed the lid, popped out the window and inserted the tall Burson v5 (I don't have the smaller v5i).
> Now much better and is no longer sounding like a downgrade.
> ...


I'm surprised the Burson v5 (mono?) makes the Little Bear B4 sound better. I swear Burson said on their website that the B4 doesn't sound better with their v5i opamp.

Burson V5I Upgrade by Burson Staff


----------



## LaughMoreDaily

Has anyone tried an Audio Jade opamp in their B4? It seems like one of the few places selling real ones...

Audio Jade - Ebay


----------



## fabien32

Barndoor said:


> V5 comes in single and dual. Mine is dual and definitely not mono.


Again as far as I know, The v5 is single and the v5i is dual. So I think you should check again.
Cheers


----------



## seamon

fabien32 said:


> Again as far as I know, The v5 is single and the v5i is dual. So I think you should check again.
> Cheers


V6, V5 and V5i all come in both dual and single versions

https://www.bursonaudio.com/product/supreme-sound-opamp-v6/
https://www.bursonaudio.com/product/supreme-sound-opamp-v5/
https://www.bursonaudio.com/product/supreme-sound-opamp-v5i/


----------



## fabien32 (Sep 12, 2020)

LaughMoreDaily said:


> Has anyone tried an Audio Jade opamp in their B4?


No, but I tried the douk audio sa200, the muses02, the v5i, and some other not worth mentioning. I'm actually testing right now the burson v6 vivid. And so far the v5i and the v6 are way better. The sa200 had a better sound than the v5i but it is very unstable and finish the battery extremely fast. So far the v6 is winning. If you'd like, can can share my findings when I reach a final conclusion?


----------



## seamon

fabien32 said:


> No, but I tried the douk audio sa200, the muses02, the v5i, and some other not worth mentioning. I'm actually testing right now the burson v6 vivid. And so far the v5i and the v6 are way better. The sa200 had a better sound than the v5i but it is very unstable and finish the battery extremely fast. So far the v6 is winning. If you'd like, can can share my findings when I reach a final conclusion?


What is that green external battery thing?


----------



## fabien32

seamon said:


> V6, V5 and V5i all come in both dual and single versions
> 
> https://www.bursonaudio.com/product/supreme-sound-opamp-v6/
> https://www.bursonaudio.com/product/supreme-sound-opamp-v5/
> https://www.bursonaudio.com/product/supreme-sound-opamp-v5i/


I stand corrected. I don't know why I thought that. good to know.
Thanks


----------



## fabien32

seamon said:


> What is that green external battery thing?


I replaced the original battery (1000mah) with a 2400mah, because it was not enough for me


----------



## seamon

fabien32 said:


> I replaced the original battery (1000mah) with a 2400mah, because it was not enough for me


Lmao the thing is as big as the whole amp itself


----------



## fabien32 (Sep 13, 2020)

seamon said:


> Lmao the thing is as big as the whole amp itself


It's True that it's big but not as big as the amp, and when i put it under, and use strong elastic bands it doesn't bother me,  And It plays much much longer


----------



## Barndoor (Sep 12, 2020)

LaughMoreDaily said:


> I'm surprised the Burson v5 (mono?) makes the Little Bear B4 sound better. I swear Burson said on their website that the B4 doesn't sound better with their v5i opamp.
> 
> Burson V5I Upgrade by Burson Staff


I think that is one users impression and not Burson's opinion. Not enough detail in the one line statement to form much of a judgement.

I purchased my v5 quite a few years ago to use in a little dot I+ it made a big improvement in that amp (I can't remember what the original opamp was, but I did flip a good few opamps at the time).
At the time the V6 didn't exist.
Reviews I read at the time gave me the impression that there was some sacrifice in performance for the smaller size of the V5i vs. the V5, so I chose the V5. I haven't heard the V5i so can't comment on its performance in the little bear.

@fabien32 I am keen to understand more why you thought the v5 might be mono. Couldn't find anything on the Burson website and the operating parameters for v5 and V5i look to be very similar.

Edit: hadn't read latest posts when replying. My v5 is a dual opamp


----------



## Mouseman

Barndoor said:


> I think that is one users impression and not Burson's opinion. Not enough detail in the one line statement to form much of a judgement.
> 
> I purchased my v5 quite a few years ago to use in a little dot I+ it made a big improvement in that amp (I can't remember what the original opamp was, but I did flip a good few opamps at the time).
> At the time the V6 didn't exist.
> ...


I have the balanced Little Bear, and they sound a lot better than the stock opamps.


----------



## Hal Rockwell

In case anyone was wondering what the pots are for. Found this shot on facebook.


----------



## LaughMoreDaily

Mouseman said:


> I have the balanced Little Bear, and they sound a lot better than the stock opamps.


That line confuses me. Balanced Little Bear? Balanced output? A balanced only version?


----------



## Mouseman

LaughMoreDaily said:


> That line confuses me. Balanced Little Bear? Balanced output? A balanced only version?


It's the Little Bear B4-X,with balanced output. I think technically it's dual mono, to a 2.5 output.


----------



## seamon

LaughMoreDaily said:


> That line confuses me. Balanced Little Bear? Balanced output? A balanced only version?


It exists but it's called Oriolus BA300s


----------



## Mouseman

seamon said:


> It exists but it's called Oriolus BA300s


Yeah, add $400.


----------



## Novice2020

Have anyone tried this little bear with dx160?
Also what is our consensus guys is b4 better than b4-x?


----------



## Barndoor

From what I read in this forum other members didn't think there was much difference between the B4 and B4-x. 
I went for the standard B4 as it only uses 1 opamp, so easier to upgrade (if you plan on going down that route).


----------



## Novice2020

Barndoor said:


> From what I read in this forum other members didn't think there was much difference between the B4 and B4-x.
> I went for the standard B4 as it only uses 1 opamp, so easier to upgrade (if you plan on going down that route).


Was your purchase worthy? I mean do you like this amp?


----------



## Barndoor

For me yes, at times I really like a warmer/smoother presentation of music, I can find it to be more relaxing and emotionally engaging. Ideal if I'm working, reading or late at night.

I'm using my Cowon P1 or Mojo with the amp going to Focal Stellia.

For critical listening for me the amp does smooth the sound at the expense of precision, detail and texture compared to not having it in the chain. So the amp gives a flavour option that for you may or may be worth the sacrifices.

It is still early days for me and I'm still to come to a final conclusion on it. With the Stellia it is quite clear that they are not performing to their full potential with this amp (I suspect all my gear are holding them back to be honest).

I haven't tried it with some of my other headphones yet (nothing else has had a look in since I got the Stellia 2 months ago), but I suspect that they will also sound smoother with the negative differences being less apparent (I have Hifiman HE400i, Senn HD6xx, Fostex TH-X00, Audeze EL8).

Note I almost immediately replaced my opamp with a burson v5 as I had one to hand. Without this change I am less inclined to answer yes to your question.


----------



## Novice2020

Barndoor said:


> For me yes, at times I really like a warmer/smoother presentation of music, I can find it to be more relaxing and emotionally engaging. Ideal if I'm working, reading or late at night.
> 
> I'm using my Cowon P1 or Mojo with the amp going to Focal Stellia.
> 
> ...


Makes sense. This Burson upgrade doubles the price of the unit pretty much


----------



## fabien32 (Sep 30, 2020)

katatonicone1 said:


> How is your muses02 experience after this time? Do you use b4 with IEMs by any chance?


after long use i decided not to use IEMs (not even the SONY-MDR-EX800ST) there is nothing that even close My LCD 2C. a after trying a all lot of OP-AMP i can say that yhe V6 vivid is one of the best (if not the best OP) I ever used 
if you want to know why than read this:
https://www.head-fi.org/showcase/burson-audio-supreme-sound-opamp-v6-vivid-and-classic.23186/reviews


----------



## fabien32 (Sep 30, 2020)

Does anyone know how to delete a post completely?


----------



## 534743

I see some people on here tinkered with their Little Bear B4-X. Could someone tell me what effect those 4 potentionmeters on the circuit board have? I guess two of them are for volume? That would be handy as one channel of my Little bear seems to be a tad louder than the other.


----------



## DBaldock9

paraphernalia said:


> I see some people on here tinkered with their Little Bear B4-X. Could someone tell me what effect those 4 potentionmeters on the circuit board have? I guess two of them are for volume? That would be handy as one channel of my Little bear seems to be a tad louder than the other.



The small potentiometers set the Grid #1 & Grid #2 Bias Points / Operating Voltages for the two tubes.
See this post - https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-14511729

Note that this appears to be the schematic for the B4 (and not the -X), since it doesn't have two dual op-amps, driving a Balanced Output - but the vacuum tube preamp section is basically the same.


----------



## Hal Rockwell

paraphernalia said:


> I see some people on here tinkered with their Little Bear B4-X. Could someone tell me what effect those 4 potentionmeters on the circuit board have? I guess two of them are for volume? That would be handy as one channel of my Little bear seems to be a tad louder than the other.



https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/page-39


----------



## Aklo09 (Nov 16, 2020)

I've just received a B4-X, I was curious to try it,
Excuse the stupid question, but how do you know when it's fully charged?
I've plugged it and there's no sign something is happening...

edit: the charger is warm while the Amp is cold


----------



## fabien32

Aklo09 said:


> I've just received a B4-X, I was curious to try it,
> Excuse the stupid question, but how do you know when it's fully charged?
> I've plugged it and there's no sign something is happening...
> 
> edit: the charger is warm while the Amp is cold


The light on the charger turns from red to green


----------



## Bosk

I recently took delivery of a B4-X and am planning to mod this great little amp. I've already ordered a pair of V5i-Ds, am planning to do the copper shielding tape mod to the interior of the case, and perhaps a few other simple things.

One question, would anyone happen to know which size of silicone o-ring dampeners will fit the 5899 tubes? I figured out 19mm apparently suits 6922s, but these 5899s are virtually half the size. The microphonics in my B4-X are rather severe so its definitely an area I'd like to address.


----------



## Aklo09

It has been written here. 9mm
I can't find 9mm rings anywhere...


----------



## fabien32 (Nov 18, 2020)

Bosk said:


> I recently took delivery of a B4-X and am planning to mod this great little amp. I've already ordered a pair of V5i-Ds, am planning to do the copper shielding tape mod to the interior of the case, and perhaps a few other simple things.
> 
> One question, would anyone happen to know which size of silicone o-ring dampeners will fit the 5899 tubes? I figured out 19mm apparently suits 6922s, but these 5899s are virtually half the size. The microphonics in my B4-X are rather severe so its definitely an area I'd like to address.


The microphonics normally can be fix with playing with the adjustment screws that can be found on both sides of the tubes


----------



## DBaldock9

Bosk said:


> I recently took delivery of a B4-X and am planning to mod this great little amp. I've already ordered a pair of V5i-Ds, am planning to do the copper shielding tape mod to the interior of the case, and perhaps a few other simple things.
> 
> One question, would anyone happen to know which size of silicone o-ring dampeners will fit the 5899 tubes? I figured out 19mm apparently suits 6922s, but these 5899s are virtually half the size. The microphonics in my B4-X are rather severe so its definitely an area I'd like to address.



I used these rings, since they fill the gap between the circuit board and the case - https://www.amazon.com/gp/product/B07ZDNHGKG/
.


----------



## Aklo09

Do you have to unsolder the tubes to install rings or they just slip in?


----------



## Bosk

fabien32 said:


> The microphonics normally can be fix with playing with the adjustment screws that can be found on both sides of the tubes


Excellent, I just have three quick questions regarding those screws please.

1. Is it safe to adjust them while power is on and music is playing?
2. Do I need to use a multimeter to adjust them properly?
3. Would reducing the gain increase battery life but worsen sound quality?

Many thanks for helping me out. I know enough electronics to perform basic mods like replacing resistors, connectors etc. but don't understand most of the theory.






DBaldock9 said:


> I used these rings, since they fill the gap between the circuit board and the case - https://www.amazon.com/gp/product/B07ZDNHGKG/


Fantastic, just what I needed. I'll order some immediately. I'm finding there's a very pronounced ringing when accidentally tapping the sides of the amp. 

There's also a very low audible buzzing sound that oscillates from high to low frequencies continuously which is evident through earphones during quiet passages and also a slight channel imbalance, though I'm guessing these are more likely solved by playing with the adjustment screws.

Thanks again for your help.


----------



## DBaldock9

Aklo09 said:


> Do you have to unsolder the tubes to install rings or they just slip in?



If your question is for me - Well, I assembled removable tube carrier boards, that plug into the main board, so the tubes were out of the unit when I installed the O-rings.
.
Removable tube carrier (back view) - 

. 
Removable tube carrier (front view) - 

. 
Litte Bear B4-X, before O-rings (top view) -


----------



## fabien32

Bosk said:


> 1. Is it safe to adjust them while power is on and music is playing?
> 2. Do I need to use a multimeter to adjust them properly?
> 3. Would reducing the gain increase battery life but worsen sound quality?


1.It is safe and even recommend to adjust them when playing
2.no multimeter is needed
3.lowering gain doesn't affect the quality of the sound in general


----------



## alvaroenoht

DBaldock9 said:


> If your question is for me - Well, I assembled removable tube carrier boards, that plug into the main board, so the tubes were out of the unit when I installed the O-rings.
> .
> Removable tube carrier (back view) -
> 
> ...


Hi!! nice mod.  Where did you get the removable tube carriers?. 
Also what type of opamps are those?. I checked and it requires dual opamps per channel. Seems to be driving them in parallel with unity gain. I was thinking about ordering some sparkos 3602, but I am afraid they wont fit, but movin the tubes out of the way maybe will make some space?. Have you mod the power supply?. I was thinking about using a usbc pdb in 12 volts to use it with an external battery bank for longer listening sessions.


----------



## Bosk

fabien32 said:


> 1.It is safe and even recommend to adjust them when playing
> 2.no multimeter is needed
> 3.lowering gain doesn't affect the quality of the sound in general


Many thanks, I'll try adjusting them and see how it goes!


----------



## DBaldock9 (Nov 18, 2020)

alvaroenoht said:


> Hi!! nice mod.  Where did you get the removable tube carriers?.
> Also what type of opamps are those?. I checked and it requires dual opamps per channel. Seems to be driving them in parallel with unity gain. I was thinking about ordering some sparkos 3602, but I am afraid they wont fit, but movin the tubes out of the way maybe will make some space?. Have you mod the power supply?. I was thinking about using a usbc pdb in 12 volts to use it with an external battery bank for longer listening sessions.



The op-amps that are in the photo are OPA-1622 (Dual Op-Amp (VSON-10) on DIP-8 header, ±18VDC), ordered from eBay.
My Sparkos SS3602 did fit in the unmodified B4-X, just barely - with one of them touching the tube on that side.
My main goal in creating the tube carriers, was to move the tubes away from the op-amp sockets.
They were made by ordering a proto-board kit from Amazon, and cutting a couple of pieces to size with an X-Acto thin-kerf saw.
Then I soldered point-to-point wiring from the pins that are soldered to the main board, to the pin sockets for the tubes.
I haven't modified the power supply circuit, yet - but that is in the planning stage.
What I'd like to have, is an "Aux" power input, that is switched in-place of the battery output, so that I can use a low noise linear 12VDC supply for desktop operation, or charge and use the internal battery for portable operation.


----------



## alvaroenoht

DBaldock9 said:


> The op-amps that are in the photo are OPA-1622 (Dual Op-Amp (VSON-10) on DIP-8 header, ±18VDC), ordered from eBay.
> My Sparkos SS3602 did fit in the unmodified B4-X, just barely - with one of them touching the tube on that side.
> My main goal in creating the tube carriers, was to move the tubes away from the op-amp sockets.
> They were made by ordering a proto-board kit from Amazon, and cutting a couple of pieces to size with an X-Acto thin-kerf saw.
> ...


great! just ordered mine and I am trying to analyze the circuit from the pictures I find in the internet while mine arrives. I was planning to do exactly what you did! but didnt seem to find anyone that tried to do it. Now that I know it can be done I will focus in the power supply. Please keep us posted with those mods!!


----------



## Bosk

DBaldock9 said:


> I haven't modified the power supply circuit, yet - but that is in the planning stage.
> What I'd like to have, is an "Aux" power input, that is switched in-place of the battery output, so that I can use a low noise linear 12VDC supply for desktop operation, or charge and use the internal battery for portable operation.


Sounds very interesting! Really looking forward to seeing how this turns out.

My electronics knowledge is pretty minimial so this may be a silly question, but would it be beneficial to add a regulator of some kind between the battery and the tubes to stabilize the voltages they're fed and possibly lower the noise floor?

I purchased a couple of 'super regulators' like these from Parts Connexion in the past and found the difference they made in DAC circuits was massive:
https://www.partsconnexion.com/BELLSPX78-85581.html
https://www.partsconnexion.com/NCLASSD-83328.html


----------



## alvaroenoht

Bosk said:


> Sounds very interesting! Really looking forward to seeing how this turns out.
> 
> My electronics knowledge is pretty minimial so this may be a silly question, but would it be beneficial to add a regulator of some kind between the battery and the tubes to stabilize the voltages they're fed and possibly lower the noise floor?
> 
> ...


The little bear have 2 dc to dc converters / regulators?  (Mornsun A1212S) for (+12v and -12v) and some big caps in front to smooth the power (at least that's what it looks from the pictures).  That regulator could be beneficial for an external power supply.  There is one guy in reddit that did that mod, and he experienced a low hum when powered from a switching power supply, The problem might be the heaters getting dirty power since they are connected in series directly to the battery.  I think that's the reason you cant power the little bear and listen to it at the same time because it doesn't have a bms and no filtering in the power input at all.
https://www.reddit.com/r/headphones..._bear_b4x_external_power_mod_a_mixed_success/
I was thinking in using a USB-C PDB at 12 volts like this https://www.amazon.com/SparkFun-Power-Delivery-Board-Distribution/dp/B084RZLTQW and adding a relay to disconnect the battery once the usbc pdb is powered and provide the power from the usb-c unit. that way I can use an external battery to power the b4-x for extended listening and when using more power hungry op/amps providing more amps, but I don't know how dirty the power is going to be. Have to try. 
As soon as I get mine I will finish drawing the schematic and post it here to see how we can further improve it.


----------



## DBaldock9

Bosk said:


> Sounds very interesting! Really looking forward to seeing how this turns out.
> 
> My electronics knowledge is pretty minimial so this may be a silly question, but would it be beneficial to add a regulator of some kind between the battery and the tubes to stabilize the voltages they're fed and possibly lower the noise floor?
> 
> ...



Back on page 20, there's modification shown, which adds regulators to each tube power supply circuit - https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-14530910

That's another thing that I'll probably try with my B4-X.


----------



## Bosk

alvaroenoht said:


> The little bear have 2 dc to dc converters / regulators?  (Mornsun A1212S) for (+12v and -12v) and some big caps in front to smooth the power (at least that's what it looks from the pictures).  That regulator could be beneficial for an external power supply.  There is one guy in reddit that did that mod, and he experienced a low hum when powered from a switching power supply, The problem might be the heaters getting dirty power since they are connected in series directly to the battery.  I think that's the reason you cant power the little bear and listen to it at the same time because it doesn't have a bms and no filtering in the power input at all.
> https://www.reddit.com/r/headphones..._bear_b4x_external_power_mod_a_mixed_success/
> I was thinking in using a USB-C PDB at 12 volts like this https://www.amazon.com/SparkFun-Power-Delivery-Board-Distribution/dp/B084RZLTQW and adding a relay to disconnect the battery once the usbc pdb is powered and provide the power from the usb-c unit. that way I can use an external battery to power the b4-x for extended listening and when using more power hungry op/amps providing more amps, but I don't know how dirty the power is going to be. Have to try.
> As soon as I get mine I will finish drawing the schematic and post it here to see how we can further improve it.


That sounds like a really interesting project. I asked the Ebay seller who sold my B4-X for a schematic but was told they can't provide one, so if you could draw a schematic for us that'd be extremely useful!





DBaldock9 said:


> Back on page 20, there's modification shown, which adds regulators to each tube power supply circuit - https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-14530910
> 
> That's another thing that I'll probably try with my B4-X.


I'll be very interested to watch your progress. Perhaps a blacker background, better dynamics & imaging would result from more stable voltage being fed to those tubes.

Just spitballing here, but would it be very difficult to mod the 3.5mm input to 2.5mm balanced instead, thereby making the amp fully balanced in the truest sense? I previously owned an ALO CDM and found the difference in performance between running it in single-ended & fully balanced modes was enormous, in the latter it really came alive.


----------



## DBaldock9

Bosk said:


> That sounds like a really interesting project. I asked the Ebay seller who sold my B4-X for a schematic but was told they can't provide one, so if you could draw a schematic for us that'd be extremely useful!
> 
> 
> 
> ...



I've got a pair of fully balanced amps - iBasso PB2 Solid-State Portable & Loxjie P20 Tube/Hybrid Desktop.
It would be great if the Little Bear B4-X was fully balanced, but modifying it, in the available space, would be a bit tricky.
.
[*A.*] If you want to be able to take a Balanced Input, and provide a Balanced Output - then you'll need to make these changes:
1.) Add a 2.5mm TRRS Input Jack
2.) Route the L+, L-, R+, R- signals to the tube pre-amplification circuit (bypassing the phase-splitter that would be needed for [*B*.])
3.) Add 2 more tubes for Balanced pre-amplification of L+, L-, R+, R-
4.) Reconfigure the current op-amps to be 4 separate buffers (instead of phase-splitters) to drive the Balanced Output
.
[*B.*] If you want to be able to take a Single-Ended Input, and provide a Balanced Output - then you'll need to make these changes:
1.) Add a phase-splitter at the Input (which is what the current op-amps are doing for the Output) to create the L+, L-, R+, R- signals
2.) Add 2 more tubes for the Balanced pre-amplification of L+, L-, R+, R-
3.) Reconfigure the current op-amps to be 4 separate buffers (instead of phase-splitters) to drive the Balanced Output
.
So the design concepts are fairly simple, but trying to add additional op-amps (w/support circuitry), and tubes (plus voltage regulators for the tubes), while still leaving space to do op-amp rolling - inside the current B4-X case - would probably require creating a completely new main circuit board, along with daughter-boards, so everything fits.


----------



## alvaroenoht (Nov 20, 2020)

DBaldock9 said:


> Back on page 20, there's modification shown, which adds regulators to each tube power supply circuit - https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-14530910
> 
> That's another thing that I'll probably try with my B4-X.


to do this mod, you will have to feed the heater filament in a separate circuit.


Bosk said:


> That sounds like a really interesting project. I asked the Ebay seller who sold my B4-X for a schematic but was told they can't provide one, so if you could draw a schematic for us that'd be extremely useful!
> 
> 
> 
> ...



I have been working on the schematics during my lunch break. The b4-x is already balanced. the circuit is balanced in the sense that each channel has an independent power supply, preamp stage and the output stage runs two opamps in parallel per channel!, the components selected seem to be of good quality too. I havent check how they grounded the 3.5 but the 2.5jack  is just in parallel with the 3.5 so you should be able to listen from both outputs at the same time.
Perhaps if we remove the 3.5 jack and remove the common ground at the output the sound will improve. I am more focused in the power supply part for now since I want to be able to increase battery time.
I noticed the dc jack is directly connected to the battery and I assume that it has a switch that shuts down a relay that cuts down power to the unit when inserted. I dont think is safe to bypass that relay and use it while connected since it doesnt have a bms and that can damage the battery, but an external battery could be used. it has 5 caps in total for smothing the power one shared before the dc to dc converters and 2 after each channel for the -12v and + 12v rails. A further improvement could be to up the voltage to 16 or 18v, but thats basically redoing the whole unit, not worth it imo.

The suggestion of having separate power supplies for the heaters I dont think is good since the heaters only need 6 volts and they dont care about ripple or noise, most heaters in big units use ac.


----------



## alvaroenoht (Nov 20, 2020)

DBaldock9 said:


> I've got a pair of fully balanced amps - iBasso PB2 Solid-State Portable & Loxjie P20 Tube/Hybrid Desktop.
> It would be great if the Little Bear B4-X was fully balanced, but modifying it, in the available space, would be a bit tricky.
> .
> [*A.*] If you want to be able to take a Balanced Input, and provide a Balanced Output - then you'll need to make these changes:
> ...




yeah! you basically have to redo the board. if you can find a dual mini sub pentode with 2 dual opamps you could get this circuit done in the same space.


----------



## DBaldock9

alvaroenoht said:


> to do this mod, you will have to feed the heater filament in a separate circuit.
> 
> 
> I have been working on the schematics during my lunch break. The b4-x is already balanced. the circuit is balanced in the sense that each channel has an independent power supply, preamp stage and the output stage runs two opamps in parallel per channel!, the components selected seem to be of good quality too. I havent check how they grounded the 3.5 but the 2.5jack  is just in parallel with the 3.5 so you should be able to listen from both outputs at the same time.
> ...



(*Emphasis* added)

Is that a Battery Management System?
If so, I think it's built into the Charger/Power Supply - since it has an LED that changes from Red (while charging) to Green (when charged).

The idea I've got, is to break the 12VDC circuit *after* the battery, and use a second power input port, fed through a switch, so that either the Aux low-noise linear 12VDC, or the Battery can feed the amplifier circuit.


----------



## alvaroenoht

DBaldock9 said:


> (*Emphasis* added)
> 
> Is that a Battery Management System?
> If so, I think it's built into the Charger/Power Supply - since it has an LED that changes from Red (while charging) to Green (when charged).
> ...



yes the bms is inside the power brick. That will certainly work. I think you can avoid the switch if you add a relay that cuts the battery and use the aux,  But I dont know if there is enough space there.


----------



## alvaroenoht

btw how is the sound with the sparkos?? I was reading the specs and they recommend 18 volts. the little bear voltage won't be optimal for it.


----------



## DBaldock9

alvaroenoht said:


> btw how is the sound with the sparkos?? I was reading the specs and they recommend 18 volts. the little bear voltage won't be optimal for it.



On their SS3601/SS3602 Engineering Data Sheet, ±18VDC is listed as the maximum recommended supply voltage, but the typical supply voltage is ±12VDC, and the minimum supply voltage is ±6VDC.

I'm currently listening to my LZ A4 earphones on the Balanced output of my B4-X (2x Sparkos SS3602), with the input coming from my Topping D70 DAC - watching Christmas Movies on the Hallmark Channel.  It all sounds great, although the Sparkos is not a high current op-amp (rated for 15mA Class A / 40mA Class AB @±12VDC).


----------



## Bosk

DBaldock9 said:


> I've got a pair of fully balanced amps - iBasso PB2 Solid-State Portable & Loxjie P20 Tube/Hybrid Desktop.
> It would be great if the Little Bear B4-X was fully balanced, but modifying it, in the available space, would be a bit tricky.
> .
> [*A.*] If you want to be able to take a Balanced Input, and provide a Balanced Output - then you'll need to make these changes:
> ...


Either of those options sound like they'd be next to impossible to complete inside the existing case and would be quite involving to perform. I guess the pertinent question would be how much sonic improvement would be likely and if that would justify the time and expense on parts. It certainly seems like there's a number of other areas of lower-hanging fruit that could be looked at first.

For instance, and again my knowledge of electronics is limited so I wouldn't know where to begin suggesting complex circuit changes, here are a few ideas of other things we B4-X owners could potentially improve: (the concept stage is always the most fun because work is completed instantly and ideas are free)

*1. *How about replacing any resistors & film caps in the signal path? Only problem with film caps it the upper-tier audiophile varieties tend to be very large & potentially worth more than the amp itself. As for resistors, I'm not sure if 0.6W is enough for the releant areas of this circuit but I used these in a TDA1543 DAC once and observed a very obvious improvement:
https://www.partsconnexion.com/vishay-z-foil-tx2575-series-radial-resistors.html

*2. *What about replacing the volume potentiometer with a stepped attenuator? Not a big Khozmo or similar unless the amp was going to be re-housed, but could something like this fit in the existing case? (don't know if 100k is the right value, just an example of the type I had in mind):
https://www.ebay.com.au/itm/DACT-Ty...m420431cfe5:g:uDsAAOSwizhdqBiW&frcectupt=true

*3.* Would there be a benefit to either upgrading the trimpots with higher-quality versions or even replacing them entirely with fixed resistors of the optimum tested value?

*4.* The power supply electrolytic caps could be replaced with nicer ones like Elna Silmic IIs, ideally in much beefier values, but the B4-X seems to have even less room back there than the B4 so again that might be mod requiring a new case. (a common theme emerges)

*5. *This is where my poor electrical theory will probably become very evident but might there be some benefit to "extending" the ground plane somehow, or doing a better job of connecting it to the case if it is already? Many Astell & Kern users have speculated the sonic differences in the higher-end models are partly due to the differing case materials which I've read are generally connected to the ground plane, copper for example possibly having a benefit over alumnium. This is really just my layman's way of saying "hey maybe grounding is important and could we improve that somehow?".

*6. *Oh and lastly -again straying into new case territory- in an ideal world it'd be nice to replace the output jack with a high quality 4.4mm Pentaconn jack. Not sure how much sonic difference that'd make.


----------



## seamon (Nov 20, 2020)

Bosk said:


> Either of those options sound like they'd be next to impossible to complete inside the existing case and would be quite involving to perform. I guess the pertinent question would be how much sonic improvement would be likely and if that would justify the time and expense on parts. It certainly seems like there's a number of other areas of lower-hanging fruit that could be looked at first.
> 
> For instance, and again my knowledge of electronics is limited so I wouldn't know where to begin suggesting complex circuit changes, here are a few ideas of other things we B4-X owners could potentially improve: (the concept stage is always the most fun because work is completed instantly and ideas are free)
> 
> ...


At that point, just get a better portable tube amp? Oriolus BA300s mkii
Edit: The Oriolus amp is also part of a stack that uses premium components: 9038Pro in the DAC, Alps Pot on the SS AMP and there were some audiophile grade components when I inspected the PCB. Also, swappable opamps at all points.


----------



## DBaldock9

Bosk said:


> Either of those options sound like they'd be next to impossible to complete inside the existing case and would be quite involving to perform. I guess the pertinent question would be how much sonic improvement would be likely and if that would justify the time and expense on parts. It certainly seems like there's a number of other areas of lower-hanging fruit that could be looked at first.
> 
> For instance, and again my knowledge of electronics is limited so I wouldn't know where to begin suggesting complex circuit changes, here are a few ideas of other things we B4-X owners could potentially improve: (the concept stage is always the most fun because work is completed instantly and ideas are free)
> 
> ...



*Just realized that I forgot one critical component, that every fully balanced amp requires - a 4-gang Potentiometer, to control the L+, L-, R+, R- signals.*

For #2, It will need to be a 4-gang stepped attenuator.

For #3, The trimpots probably need to remain, since every tube is different, and may also need adjusting as it ages.

For #5, I did add a GND wire around the Volume Control shaft, so that when the nut is tightened, the "front" panel is solidly grounded.

For #6, I recently looked, but haven't been able to find the chassis mount Pentaconn jacks for sale on AliExpress or in Google Searches - and only the one VERY EXPENSIVE ($66.75 each) listing on eBay.  A number of vendors sell the cable mount Plugs, and some have the cable mount Jacks - but the chassis mount jacks aren't readily available to the general public.


----------



## Bosk (Nov 23, 2020)

seamon said:


> At that point, just get a better portable tube amp? Oriolus BA300s mkii
> Edit: The Oriolus amp is also part of a stack that uses premium components: 9038Pro in the DAC, Alps Pot on the SS AMP and there were some audiophile grade components when I inspected the PCB. Also, swappable opamps at all points.


Thanks for letting me know! This was the first I've heard of that amp, having been out of the hobby for a couple of years.

So I just put in an order for one on Aliexpress, they're on special for AU$460. (roughly US$337)
https://www.aliexpress.com/item/330...earchweb0_0,searchweb201602_,searchweb201603_

I'll compare it with the B4-X once it arrives and let you guys know my findings.


----------



## seamon

Bosk said:


> Thanks for letting me know! This was the first I've heard of that amp, having been out of the hobby for a couple of years.
> 
> So I just put in an order for one on Aliexpress, they're on special for AU$460. (roughly US$337)
> https://www.aliexpress.com/item/330...earchweb0_0,searchweb201602_,searchweb201603_
> ...


Perfect. Please let us know how they compare ASAP!


----------



## DBaldock9

seamon said:


> At that point, just get a better portable tube amp? Oriolus BA300s mkii
> Edit: The Oriolus amp is also part of a stack that uses premium components: 9038Pro in the DAC, Alps Pot on the SS AMP and there were some audiophile grade components when I inspected the PCB. Also, swappable opamps at all points.



Unfortunately, there appears to be several different Oriolus BA300S amp models.
The way to tell them apart, is to see where the jacks are mounted, and whether there's a power LED.
Since the B300S doesn't have a Volume Control, it's not exactly equivalent to the B4-X.
And, the B300S is Balanced Input to Balanced Output ***ONLY***, so I don't think you can directly connect an Unbalanced signal (like a phone) to the Input.
.
I came across this video comparison of the Oriolus B300S & Little Bear B4-X (but I haven't watched it yet) -
.


----------



## Barndoor

DBaldock9 said:


> Unfortunately, there appears to be several different Oriolus BA300S amp models.
> The way to tell them apart, is to see where the jacks are mounted, and whether there's a power LED.
> Since the B300S doesn't have a Volume Control, it's not exactly equivalent to the B4-X.
> And, the B300S is Balanced Input to Balanced Output ***ONLY***, so I don't think you can directly connect an Unbalanced signal (like a phone) to the Input.
> ...



Looks like he has replaced the chips in his little bear. Burson v5i maybe?


----------



## seamon

DBaldock9 said:


> Unfortunately, there appears to be several different Oriolus BA300S amp models.
> The way to tell them apart, is to see where the jacks are mounted, and whether there's a power LED.
> Since the B300S doesn't have a Volume Control, it's not exactly equivalent to the B4-X.
> And, the B300S is Balanced Input to Balanced Output ***ONLY***, so I don't think you can directly connect an Unbalanced signal (like a phone) to the Input.
> ...



There are 2 Oriolus BA300s Models - mki and mkii. I have both and currently selling the mki after getting mkii. 
mki was designed as a amp for the Sony ZX300 DAP I believe. mkii was designed to be a preamp between their BD20 DAC and BA20 AMP. I have the entire stack with me.

The difference between mki and mkii is that mki boosts the signal by +3dB. mki has 3 stages - Tube Stage, Opamp gain stage and Opamp Buffer stage. mkii skips the gain stage and only has a tube stage + Opamp Buffer stage. 

Sonically, mkii is warmer and has a more tubey sound.



Barndoor said:


> Looks like he has replaced the chips in his little bear. Burson v5i maybe?


Yep looks to be Burson V5i


----------



## seamon

DBaldock9 said:


> Unfortunately, there appears to be several different Oriolus BA300S amp models.
> The way to tell them apart, is to see where the jacks are mounted, and whether there's a power LED.
> Since the B300S doesn't have a Volume Control, it's not exactly equivalent to the B4-X.
> And, the B300S is Balanced Input to Balanced Output ***ONLY***, so I don't think you can directly connect an Unbalanced signal (like a phone) to the Input.
> ...



Also, you can connect an Unbalanced Output from a phone (3.5mm) to the Balanced Input on the BA300s(4.4mm). You need a custom cable for that.
Source: Have a custom cable for exactly this purpose.


----------



## alvaroenoht

Bosk said:


> Thanks for letting me know! This was the first I've heard of that amp, having been out of the hobby for a couple of years.
> 
> So I just put in an order for one on Aliexpress, they're on special for AU$460. (roughly US$337)
> https://www.aliexpress.com/item/330...earchweb0_0,searchweb201602_,searchweb201603_
> ...


The BA300s seems to be an otl tube amp.. the little bear is a hybrid one. I dont know what the output impedance of the Oriolus could be, but seems to be designed for high impedance headphones..


----------



## seamon (Nov 23, 2020)

alvaroenoht said:


> The BA300s seems to be an otl tube amp.. the little bear is a hybrid one. I dont know what the output impedance of the Oriolus could be, but seems to be designed for high impedance headphones..


The BA300s is not OTL. mki has 4xLMH6643MA(+3dB Gain + Buffer) on the output stage and mkii has 2xLMH6643MA(Buffer) on the output stage.

Edit:
LMH6643MA Output Impedance is actually very very low.





I have used it to drive my 42Ohm Diana V2.


----------



## alvaroenoht

seamon said:


> The BA300s is not OTL. mki has 4xLMH6643MA(+3dB Gain + Buffer) on the output stage and mkii has 2xLMH6643MA(Buffer) on the output stage.
> 
> Edit:
> LMH6643MA Output Impedance is actually very very low.
> ...


nice!. is any of the opamps swappable?


----------



## seamon

alvaroenoht said:


> nice!. is any of the opamps swappable?


In the mkii, since the opamps are just acting as Buffers with around 150mA of current, there's really no need to swap them. Most audiophile opamps can't do more than 50mA. In the mki, you can't swap out the gain stage.


----------



## Bosk

seamon said:


> Also, you can connect an Unbalanced Output from a phone (3.5mm) to the Balanced Input on the BA300s(4.4mm). You need a custom cable for that.
> Source: Have a custom cable for exactly this purpose.


Great to know - I wasn't sure if this could be done safely. That will allow me to use the BA300s with my iPad for movies as well.

Hopefully the V5i-D's I ordered for the B4-X will be here before the BA300s arrives, so I'll be able to duplicate the comparison in that video. Not sure if he was using the BA300s 2020 version which is what I'll be comparing it to.


----------



## seamon

Bosk said:


> Great to know - I wasn't sure if this could be done safely. That will allow me to use the BA300s with my iPad for movies as well.
> 
> Hopefully the V5i-D's I ordered for the B4-X will be here before the BA300s arrives, so I'll be able to duplicate the comparison in that video. Not sure if he was using the BA300s 2020 version which is what I'll be comparing it to.


He's using the old BA300s


----------



## alvaroenoht

Has anyone already tried the power supply mod?.


----------



## alvaroenoht

DBaldock9 said:


> *Just realized that I forgot one critical component, that every fully balanced amp requires - a 4-gang Potentiometer, to control the L+, L-, R+, R- signals.*
> 
> For #2, It will need to be a 4-gang stepped attenuator.
> 
> ...


https://a.aliexpress.com/_msDFN1X could this work?


----------



## DBaldock9

alvaroenoht said:


> https://a.aliexpress.com/_msDFN1X could this work?



You'd need to verify that the metal shell is isolated from all 4 signal pins - so that none of the signals get shorted to the case, which is GND.


----------



## Bosk

Allow me to report on my recent portable amp developments.

A few days ago the Oriolus BA300S arrived and I've been burning it in ever since. After conducting a final listening test today I arrived at the conclusion it is not the answer. I don't know if its because I'm using it with A&K DAPs rather than Sony which I assume its been tuned to match, but the sound is too dark and the soundstage too narrow to match either of my DAPs satisfactorily. The Little Bear B4-X is a far better match and it isn't even close. As a result Operation Little Bear Transformation has been launced, and to that end no time or expense will be spared making it all it can be.

So about two hours ago I retrieved my old soldering iron and brushed off the dust that been collecting for the better part of three years since last using it. As luck would have it I'd built up a small collection of audiophile caps, resistors and such from those DIY days and so was lucky enough to find a number of Elna Silmic II electrolytic capacitors ready to use. For those not versed in DIY, in those days (and perhaps still today?) Silmic II's were commonly regarded as the highest quality electroytic caps available now that Black gates are no longer being made.
The largest caps with through hole leads small enough to fit the B4-X's existing board was a quad of Silmic II 220uF 16v, more than double the capcitance of the Rubycon branded 100uF 25v power supply caps they replaced. Yes they're too large to fit inside the existing case properly and are only in there temporararily because I was eager to hear if they'd make any difference.

Well. Without knowing how much difference is due to the larger values providing a greater reservoir of power storage and how much can be attributed to them being higher-grade components, the change in sound is of a similar magnitude to what I experienced replacing the stock OPAMPs with Burson V5is.
Pardon me for gushing a little but there have been across the board changes. Deeper bass -especially sub bass- was immediately the most notable thing, but the soundstage has also widened and deepend, there is better articulation, and the dynamics are better. I would liken the overall effect to the feeling of upgrading to a significantly more expensive amp, and whereas before I was somewhat on the fence about using the B4-X with my SP1000 & Lunas, feeling like as much was taken away as was added, now there's no question I'm more satisfied with the amp in the chain.

Next I plan to upgrade the resistors, and would also LOVE to upgrade the battery but have not found a good replacement - does anyone know where I can source a 12v (or is it 12.6V?) 2-4000 mAh battery to replace the rather wimpy existing 1000 mAh one? Four hours of playback just isn't enough for an entire evening.



Pardon the quick & dirty photo!


----------



## Bosk

Quick question please, would anyone happen to know if the Burson V6 discrete OPAMP's have enough room to fit the B4-X?


----------



## Mouseman

Bosk said:


> Quick question please, would anyone happen to know if the Burson V6 discrete OPAMP's have enough room to fit the B4-X?


They are way too tall. I think there's a picture in the thread where someone installed them, with the window popped out.


----------



## DBaldock9

Bosk said:


> Quick question please, would anyone happen to know if the Burson V6 discrete OPAMP's have enough room to fit the B4-X?



I increased the size of the opening in the top of my B4-X, and the V6 op-amps fit. 
.


----------



## Bosk

DBaldock9 said:


> I increased the size of the opening in the top of my B4-X, and the V6 op-amps fit.
> .


Excellent! I've just ordered a pair and look forward to comparing them with the V5i's. Might need to remove the plastic cases though as I don't plan on moving my tubes.

Speaking of tubes do we know of any substitues that might offer a different sonic flavor?


----------



## DBaldock9

Bosk said:


> Excellent! I've just ordered a pair and look forward to comparing them with the V5i's. Might need to remove the plastic cases though as I don't plan on moving my tubes.
> 
> Speaking of tubes do we know of any substitues that might offer a different sonic flavor?



I don't think there's a cross reference / replacement tube for the JAN5899.
But, there are some eBay vendors who sell "matched" sets of JAN5899 tubes.


----------



## Bosk

DBaldock9 said:


> I don't think there's a cross reference / replacement tube for the JAN5899.
> But, there are some eBay vendors who sell "matched" sets of JAN5899 tubes.


I found these Sylvania/s on eBay (it isn't clear if he has more than one) which look interesting:
https://www.ebay.com.au/itm/Vintage...u-Pentode-Valve-BangyBang-Tubes-/274082978998


Do you mind if I ask a question about resistors?

I measured all 10 B4-X fixed resistors -albeit with a cheap multimeter- and their values are: 2.5k ohm (x2) 118k ohm (x2) 25 ohm (x4) and 30k ohm (x2).
I'd like to replace them with Caddock MK232 which replace the excellent MK132's I've used in the past, but they aren't available in the exact values. Do you think their values would be "close enough"?
Default values are: 25, 2.5k, 30k and 118k - whereas Mouser have MK232's in the closest values of 20, 2k, 50k, and 100k.

Otherwise I could use Caddock MP930 resistors which come in 25, 2.5k, 30k and 125k, but they are TO-220 package and there isn't a lot of room on the board, plus the leads are thick. There may be other brands of small form factor high-end resistors that are a major upgrades on the (Dale?) resistors the amp comes with that I'm not aware of.

https://au.mouser.com/Passive-Compo...-Through-Hole/_/N-7gz43?Keyword=MK232&FS=True
https://au.mouser.com/ProductDetail/Caddock/MP930-250-1?qs=d6ViQafmxQTraVb%2BhhZS4A==


----------



## DBaldock9 (Dec 12, 2020)

While I knew about the Raytheon JAN5899, since it's being used in the Little Bear B4 & B4-X, I noticed that there's a surprising number of other Subminiature Pentodes, including Russian Military tubes, available on eBay.
Link to a copy of the Raytheon JAN5899 datasheet - https://frank.pocnet.net/sheets/138/5/5899.pdf
Link to an interesting thread about Russian Subminiature Tubes, on the RadioMuseum Forums - https://www.radiomuseum.org/forum/russian_subminiature_tubes.html
It would be interesting to find out whether the power supply circuit in the B4-X would work with some of those Russian tubes.
.
I've never done any indepth research on resistors - but I thought that Dale was a good brand for audio gear.


----------



## Bosk

A bit like Wima film caps, Dale resistors are ofted used on cheap entry-level gear from China. I suspect its because they've earned some recognition in the DIY community as an affordable choice that performs decently. 

Unfortunately I'm an audiophile and "decent" performance has never satisfied me! I've replaced Dale resistors with MK132's and Vishay Z-Foils in the past and the difference has been tremendous when substituting resistors in the signal path. Unfortunately I don't have a schematic for the B4-X so I'm not sure which of those 10 resistors are in the signal path, it probably won't make much of a difference replacing those that aren't. Of course the film caps would ideally be upgraded too but there's so little room on the board in that region, and any high-end 2.2uF film caps like Mundorf Supremes would as wide as the board itself.

What I have found from my experiments in the past is that the more you improve and upgrade a piece of audio gear the more cumulative benefit is incurred from each improvement. So replacing those films caps for instance might not be worth it on a stock B4-X board but if everything else were upgraded beforehand then the difference in doing so would be more noticable and therefore worthy of the time & expense.


----------



## Bosk

I'm still waiting for parts to arrive, would there be any sonic advantage from powering each tube and op-amp from a separate regulator & supply caps?


----------



## DBaldock9

Bosk said:


> I'm still waiting for parts to arrive, would there be any sonic advantage from powering each tube and op-amp from a separate regulator & supply caps?



I suspect that improving the power supplies can help the audio performance.


----------



## Bosk

DBaldock9 said:


> I suspect that improving the power supplies can help the audio performance.


I think you're right. I'll start investigating options then.


----------



## Bosk

The Burson V6 Vivid op-amps arrived today! The improvements over the V5i-Ds are immediately obvious, everything sounds noticably smoother with a layer of grit previously present wiped away, there's a greater feeling of precision and musicality, and the soundstage feels satisfyingly deeper. I feel much more emotionally connected with the music, particularly evident with midrange vocals.

Despite the difference in price they are undoubtedly worth the extra expense, that aside the only downside -according to the datasheet- is increased power draw, but for that I've connected a new 12V 5500mAh battery which should ensue all-day playback. I've also installed some extra power supply caps on the back side of the board but they didn't seem to make much difference. Suffice to say the amp won't be winning any beauty contests in its present state, eventually I'm thinking of re-housing it in a DIY perspex case which should be easier to construct than most other options.


----------



## SBMonster

Bosk said:


> The Burson V6 Vivid op-amps arrived today! The improvements over the V5i-Ds are immediately obvious, everything sounds noticably smoother with a layer of grit previously present wiped away, there's a greater feeling of precision and musicality, and the soundstage feels satisfyingly deeper. I feel much more emotionally connected with the music, particularly evident with midrange vocals.
> 
> Despite the difference in price they are undoubtedly worth the extra expense, that aside the only downside -according to the datasheet- is increased power draw, but for that I've connected a new 12V 5500mAh battery which should ensue all-day playback. I've also installed some extra power supply caps on the back side of the board but they didn't seem to make much difference. Suffice to say the amp won't be winning any beauty contests in its present state, eventually I'm thinking of re-housing it in a DIY perspex case which should be easier to construct than most other options.



Does the battery fit into the housing ?


----------



## SBMonster

Hi everyone! 
Did anyone tried to pair this amp with Senn’s hd 560s?


----------



## Bosk

SBMonster said:


> Does the battery fit into the housing ?


The new 5500mAh battery doesn't, I'll need to build a new case to house it and the PCB. It would be almost impossible to fit a battery larger than the default in the original case.


----------



## DBaldock9

Bosk said:


> The new 5500mAh battery doesn't, I'll need to build a new case to house it and the PCB. It would be almost impossible to fit a battery larger than the default in the original case.



Unless you have a convenient local supplier, here's a handy AliExpress shop with a wide selection of Aluminum enclosures - https://www.aliexpress.com/store/418985


----------



## Bosk

DBaldock9 said:


> Unless you have a convenient local supplier, here's a handy AliExpress shop with a wide selection of Aluminum enclosures - https://www.aliexpress.com/store/418985


Some of those look quite smart, thanks for the link. I do tend to wonder if there'd be any sonic benefit in terms of shielding by using a metal enclosure rather than something simpler such as sandwiching the board between two sheets of perspex separated by PCB standoffs.


----------



## Bosk

So @DBaldock9 have you tried decoupling your op-amps yet?

I'd like to give it a try and have some Wima 0.1uF film caps on hand, but the article on Burson's website is slightly confusing and I'm not exactly sure which pins they should be soldered to:

https://www.bursonaudio.com/burson-ss-opamp-101-part-1-mkp-cap-tweak/


----------



## DBaldock9

Bosk said:


> So @DBaldock9 have you tried decoupling your op-amps yet?
> 
> I'd like to give it a try and have some Wima 0.1uF film caps on hand, but the article on Burson's website is slightly confusing and I'm not exactly sure which pins they should be soldered to:
> 
> https://www.bursonaudio.com/burson-ss-opamp-101-part-1-mkp-cap-tweak/



I did install the pairs of Ceramic & Tantalum caps on the back of B4-X circuit board, back in May. They're connected to the V+ and V- pins of the op-amp sockets.
.


----------



## Bosk

DBaldock9 said:


> I did install the pairs of Ceramic & Tantalum caps on the back of B4-X circuit board, back in May. They're connected to the V+ and V- pins of the op-amp sockets.
> .


Very nice, did you notice much improvement? May I also ask if there's any particular benefit to star grounding them?


----------



## DBaldock9

Bosk said:


> Very nice, did you notice much improvement? May I also ask if there's any particular benefit to star grounding them?



I didn't really notice any obvious changes in the sound - the tubes are still a bit noisy while they're warming up, and then everything sounds good after a couple of minutes.
.
The capacitors are grounded to the point on the circuit board that's actually labeled as GND.


----------



## Bosk

Well I just performed the mod (yes I'm keen) with some Russian surplus PIO 0.047 caps I had on hand -the Wima's were actually 0.1nF and might've been a little wimpy- and yes there may be a slight improvement particularly in the high frequencies. The soundstage also feels slightly deeper but its difficult to know if that's just my imagination.

With regards to noise, background noise levels were one of the weakest aspects of the stock amp. However things improved dramatically after swapping out the battery and now its virtually silent without that annoying oscillating crackle.


----------



## SBMonster (Dec 23, 2020)

My unit is just arrived. I’m impressed overall, but I noticed that on higher volume the left side starts to be distorted and it is very noticeable, but the left and right channels are same volume. I also noticed when i switch it on, the left tube lights up faster and a bit brighter than the right one. Could you guys tell me if there is any solution to this?


----------



## SBMonster

Just paired them up for a test.





Looks like they fixed the "Daul" thing, and also the things related to interference caused by cellphones? so far i can't hear any of it.


----------



## DBaldock9

SBMonster said:


> My unit is just arrived. I’m impressed overall, but I noticed that on higher volume the left side starts to be distorted and it is very noticeable, but the left and right channels are same volume. I also noticed when i switch it on, the left tube lights up faster and a bit brighter than the right one. Could you guys tell me if there is any solution to this?



There are two small Pots for each tube, that you can try adjusting a bit - to set the operating point voltage - so they have more equal headroom.


----------



## SBMonster (Dec 23, 2020)

Thank you for your quick response. Are those the ones on the outside of the tubes or the ones in the middle?
I connected it to my computer also to my iphone. If i turn the volume over 60-70 percent and about 90 on the b4 there is a lot of distortion on both channel. Is this normal? op amp change solves this? I like to listen music loud sometimes, but this thing barely louder(without distortion) than my devices.


----------



## DBaldock9

SBMonster said:


> Thank you for your quick response. Are those the ones on the outside of the tubes or the ones in the middle?
> I connected it to my computer also to my iphone. If i turn the volume over 60-70 percent and about 90 on the b4 there is a lot of distortion on both channel. Is this normal? op amp change solves this? I like to listen music loud sometimes, but this thing barely louder(without distortion) than my devices.



There's one Pot on the "outside", and one on the "inside" - for each tube.
I'm not entirely sure which one to start with, when making adjustments.


----------



## Bosk

Would it be a lot of trouble to convert to balanced input? I could purchase a balanced volume pot but the grounds for each channel would need to be separated throughout the amp I'm assuming.

Is 100k the correct potentiometer value?


----------



## DBaldock9

Bosk said:


> Would it be a lot of trouble to convert to balanced input? I could purchase a balanced volume pot but the grounds for each channel would need to be separated throughout the amp I'm assuming.
> 
> Is 100k the correct potentiometer value?



Fully Balanced is literally 4 separate amplifier channels (L+, L-, R+, R-), which probably means 4 tubes, and the 2 dual op-amps.
.
The Potentiometer is just an input attenuator, providing a load for the source.
If it's before the input DC blocking capacitor, then the value doesn't need to be considered, as far as affecting the bias voltages on the tube circuit.


----------



## Bosk

DBaldock9 said:


> Fully Balanced is literally 4 separate amplifier channels (L+, L-, R+, R-), which probably means 4 tubes, and the 2 dual op-amps.
> .
> The Potentiometer is just an input attenuator, providing a load for the source.
> If it's before the input DC blocking capacitor, then the value doesn't need to be considered, as far as affecting the bias voltages on the tube circuit.


Thanks for clearing that up, it would definitely be a project far beyond my skill level. Back on firmer ground would you happen to know the value of the potentiometer or can you advise me on how I'd go about measuring it with a multimeter please? 

I've considered replacing it with a stepped attenuator -having had great results with them before- but will probably opt for a higher-quality volume pot instead as the amp adds so much gain to a DAP in line-out mode that I listen fairly close to the minimum point after channels are matched and would be concerned even a 47 step attenuator would lack enough levels of usable volume before things just get too loud.


----------



## alvaroenoht

SBMonster said:


> Thank you for your quick response. Are those the ones on the outside of the tubes or the ones in the middle?
> I connected it to my computer also to my iphone. If i turn the volume over 60-70 percent and about 90 on the b4 there is a lot of distortion on both channel. Is this normal? op amp change solves this? I like to listen music loud sometimes, but this thing barely louder(without distortion) than my devices.


Hi! I have the same problem. I cant pass 2 o clock without getting tons of distortion. The left is also out of balance. I know it can be adjusted with the pots but I just compensate on the source. But the distortion I read is fixed with better opamps. I have 2 OPA1622 on their way and hope this solves the problem.


----------



## Bosk

I recently put in orders for a Penon Totem 3.5mm interconnect and a new IEM cable (CEMA Tianwaitian) along with _another_ Little Bear B4-X amp. I plan to mod the second one differently and now have some insurance in case the worst should happen and I kill the first board. 

Links to the cables:
https://penonaudio.com/audio-cable/3.5mm-cable/penon-totem-audio-cable.html
https://www.aliexpress.com/item/1005001446578292.html


This will be my first experience with palladium-plated cables and the results should be interesting. Meanwhile the resistors I ordered for the B4-Xs (plural) arrived today so they'll be replacing those Dales shortly.


----------



## Bosk

The new resistors are in place. I used 0.25w Takman Carbon Films, except for the two 2.2k input resistors in the signal path which were replaced with Vishay Z-Foils. 

The change has been pronounced and extremely satisfying. There is more detail, a blacker background, the soundstage feels more solid and believable, but most of all everything flows much better and it sounds more like listening to music rather than an audio system trying to reproduce music. The lazy description would be a more analog sound, with a significant amount of digital grit swept away. This effect is consistent with my experience using Z-Foils in a TDA1543 DAC a number of years ago. At US$16 per resistor I have difficulty justifying using them outside the signal path, but along it they are absolutely worth the money. Very highly recommended mod.

I've decided to keep the amp in its' original case rather than build a larger one for it, (though the 5500mAh battery is far too large to fit so that will rest underneath in traditional DAP/AMP sandwich fashion) and plan to destroy the input traces on the PCB from the 3.5mm jack to the OP-AMP and replace them with OCC wiring, (plenty of room inside the case under the PCB provided wire gauge isn't too large) however that leaves those dubious WIMA input capacitors. Unfortunately all decent audiophile 2.2uF film caps are enormous by comparison, I could mount some on top of the case towards the rear and then trail the wires inside but that would nullify having the amp packed a snug little case to some extent. I'm mindful that just as diminishing returns are a reality when buying increasingly expensive off-the-shelf gear, so is the reverse when you start modding stuff - the more you remove junk from the signal path the more cumulative benefit is to be gained from each additional step, so naturally I'm tempted.


----------



## allaces305

Can anyone please help me with barrel/ tip size of the charging cable that fits the B4-X perfectly....i lost the original charger and need to by a universal charger that brings many sized tips..... Thank you in advance.


----------



## DBaldock9

allaces305 said:


> Can anyone please help me with barrel/ tip size of the charging cable that fits the B4-X perfectly....i lost the original charger and need to by a universal charger that brings many sized tips..... Thank you in advance.



*NOTE:* You need to buy a Li-Ion charger, and not just a generic 12.6V charger.
Last year, I bought a spare 12.6V @ 1A Li-Ion charger (to use at work) from Amazon - but it's not available any longer.
The size of the plug is 3.5mm x 1.35mm.


----------



## allaces305

DBaldock9 said:


> *NOTE:* You need to buy a Li-Ion charger, and not just a generic 12.6V charger.
> Last year, I bought a spare 12.6V @ 1A Li-Ion charger (to use at work) from Amazon - but it's not available any longer.
> The size of the plug is 3.5mm x 1.35mm.


Omg thank you so much bro and have a great new years!


----------



## DBaldock9

allaces305 said:


> Omg thank you so much bro and have a great new years!



You're welcome.
The Li-Ion chargers that have an LED, which changes from Red (while charging), to Green (when charged), is the type you probably need for the B4-X.


----------



## Bosk

After reading that higher voltage electrolytic caps generally have lower ESR I swapped out the 4x 220uF 16v Silmic II's in the power supply for 4x 470uF 63v versions and the improvements in detail levels & imaging have been significant. Its difficult to know if the increase in capacitance is responsible, or the higher cap rating. Drawbacks of the 63v versions other than price increase are the enormous size, and increased power draw which shouldn't be an issue with a 5500 mAh battery.

The B4-X is now sounding superb, like a genuinely high end piece of equipment. I think there's plenty more scope for improvement though.


----------



## beanxinh

Hi guys,

I intend to mod the power to 4x 18650 Li-po cells so that I can easily change the battery. My question is that the 18650 cell is 3.7 V so 4 of them is 14.8v while the letters on the b4x's board show that it support 12.6v, so does that damage the little bear? Are there any modification that I need to do ?

Thank


----------



## elvispreasley

Bosk said:


> After reading that higher voltage electrolytic caps generally have lower ESR I swapped out the 4x 220uF 16v Silmic II's in the power supply for 4x 470uF 63v versions and the improvements in detail levels & imaging have been significant. Its difficult to know if the increase in capacitance is responsible, or the higher cap rating. Drawbacks of the 63v versions other than price increase are the enormous size, and increased power draw which shouldn't be an issue with a 5500 mAh battery.
> 
> The B4-X is now sounding superb, like a genuinely high end piece of equipment. I think there's plenty more scope for improvement though.



What a beastie looking little bear! You went above and beyond with nodding of this little fellow)
Am I right saying that you also made tubes swappable? Your tubes PCB looks different then the stock one. If I'm right - can you please share the details of this mode, as I really want to do the same with mine B-4x


----------



## DBaldock9

Bosk said:


> The new resistors are in place. I used 0.25w Takman Carbon Films, except for the two 2.2k input resistors in the signal path which were replaced with Vishay Z-Foils.
> 
> The change has been pronounced and extremely satisfying. There is more detail, a blacker background, the soundstage feels more solid and believable, but most of all everything flows much better and it sounds more like listening to music rather than an audio system trying to reproduce music. The lazy description would be a more analog sound, with a significant amount of digital grit swept away. This effect is consistent with my experience using Z-Foils in a TDA1543 DAC a number of years ago. At US$16 per resistor I have difficulty justifying using them outside the signal path, but along it they are absolutely worth the money. Very highly recommended mod.
> 
> I've decided to keep the amp in its' original case rather than build a larger one for it, (though the 5500mAh battery is far too large to fit so that will rest underneath in traditional DAP/AMP sandwich fashion) and plan to destroy the input traces on the PCB from the 3.5mm jack to the OP-AMP and replace them with OCC wiring, (plenty of room inside the case under the PCB provided wire gauge isn't too large) however that leaves those dubious WIMA input capacitors. Unfortunately all decent audiophile 2.2uF film caps are enormous by comparison, I could mount some on top of the case towards the rear and then trail the wires inside but that would nullify having the amp packed a snug little case to some extent. I'm mindful that just as diminishing returns are a reality when buying increasingly expensive off-the-shelf gear, so is the reverse when you start modding stuff - the more you remove junk from the signal path the more cumulative benefit is to be gained from each additional step, so naturally I'm tempted.



I've found a shop here in Texas, that has the Takman 1/4W Carbon Film and Metal Film Resistors.
Are the carbon film resistors recommended in audio circuits, over the metal film resistors?
What wattage rating are the 2.2KΩ Vishay Z-Foil resistors that you used?


----------



## Bosk

DBaldock9 said:


> I've found a shop here in Texas, that has the Takman 1/4W Carbon Film and Metal Film Resistors.
> Are the carbon film resistors recommended in audio circuits, over the metal film resistors?
> What wattage rating are the 2.2KΩ Vishay Z-Foil resistors that you used?


The folklore I've read at places like diyaudio.com is that carbon resistors in general have a more natural sound, but innately higher tolerances than metal films, and so might be more suitable for placement along the signal path but not in places like say voltage regulator circuits where you might want the most accurate values possible. Some people absolutely swear by them. There are also staunch advocates for tantalum resistors like Shinkohs which are more expensive. The Vishay Z-foils are only available in 0.6w, and with the B4-X being a 12V circuit I just assumed that'd be sufficient.

I forgot to mention that since replacing all the Dale resistors the amp seems much quieter now. There's still a very soft occasional background clicking/thumping sound but the crackling static that was often fairly prevalent has virtually disappeard.





elvispreasley said:


> What a beastie looking little bear! You went above and beyond with nodding of this little fellow)
> Am I right saying that you also made tubes swappable? Your tubes PCB looks different then the stock one. If I'm right - can you please share the details of this mode, as I really want to do the same with mine B-4x


Thanks! I haven't touched the tubes except to add tube dampeners to deal with what were originally pretty severe microphonics if the case was knocked accidentally. So it came with those little PCB 'daughter-boards' pre attached but they are soldered in.

DBaldock9 has modded his B4-X's tubes connectors though, and from memory someone earlier in the thread did add sockets to make the tubes easily swappable.


----------



## DBaldock9

Bosk said:


> The folklore I've read at places like diyaudio.com is that carbon resistors in general have a more natural sound, but innately higher tolerances than metal films, and so might be more suitable for placement along the signal path but not in places like say voltage regulator circuits where you might want the most accurate values possible. Some people absolutely swear by them. There are also staunch advocates for tantalum resistors like Shinkohs which are more expensive. The Vishay Z-foils are only available in 0.6w, and with the B4-X being a 12V circuit I just assumed that'd be sufficient.
> 
> I forgot to mention that since replacing all the Dale resistors the amp seems much quieter now. There's still a very soft occasional background clicking/thumping sound but the crackling static that was often fairly prevalent has virtually dissappeard.
> ...



I realize that you're on the other side of the world, but where did you buy the Vishay 2.2KΩ 0.6W resistors?
They don't appear to be available here in the USA.


----------



## Bosk

DBaldock9 said:


> I realize that you're on the other side of the world, but where did you buy the Vishay 2.2KΩ 0.6W resistors?
> They don't appear to be available here in the USA.


Ahh, I generally purchase high-end DIY components from Parts Connexxion (as in the case of those Vishays) or Hifi Collective. Silmic II's are also stocked by Mouser.

Here's the links:
https://www.partsconnexion.com/vishay-z-foil-tx2575-series-radial-resistors.html
https://www.hificollective.co.uk/
https://au.mouser.com/ProductDetail...=/ha2pyFadugFyEyxOhML3IHT/R9A7CeWLAfyLgMrRb4=


----------



## DBaldock9

Bosk said:


> Ahh, I generally purchase high-end DIY components from Parts Connexxion (as in the case of those Vishays) or Hifi Collective. Silmic II's are also stocked by Mouser.
> 
> Here's the links:
> https://www.partsconnexion.com/vishay-z-foil-tx2575-series-radial-resistors.html
> ...



Thanks! 
I had seen the HiF Collective, and that there were some other non-US websites, but I guess I didn't look thoroughly enough to find the 0.6W Z-Foil resistors. It's weird that there doesn't seem to be any US vendors that stock them.


----------



## Bosk

DBaldock9 said:


> Thanks!
> I had seen the HiF Collective, and that there were some other non-US websites, but I guess I didn't look thoroughly enough to find the 0.6W Z-Foil resistors. It's weird that there doesn't seem to be any US vendors that stock them.


You could try emailing Vishay themselves for a list of distributors but it might just be easier to order them from Parts Connexxion in Canada.

Interestingly, Hifi Collective sell the Charcroft range of Z-foils which are I think a variant of the same resistors, but I'm yet to try them.
https://www.hificollective.co.uk/components/car_resistors.html


----------



## Bosk

I've performed the wire mod, severing all PCB traces from the 3.5mm input jack to the potentiometer, to the Z-foil resistors, to the input caps, and then to the op-amps.
I replaced them with hand-cut lengths of 26AWG 4N OCC silver wire, and used 4% silver solder on those joints. (first time using lead-free solder, i miss the shiny joints of 60/40)

The sonic difference is _enormous_. Early last night after performing the mod the amp was almost unlistenable, possibly because the solder joints were breaking in, the extra detail had a slight metallic ringing and was so fatiguing I could barely tolerate it. It has already settled in this morning -or my brain has adjusted to what I'm hearing- and is sounding much better. Still a touch on the cold side, but the added magnification of the very tiniest of details is extremely obvious and bass & dynamics have improved too. The amp is also noticably louder at the same position on the volume wheel, significantly so.

I wasn't even sure this particular mod would be worth the trouble so this is very surprising. Now I'm considering the difference using a larger gauge wire would make make, perhaps mixing both OCC silver & copper conductors for a warmer, more forgiving sonic balance.


----------



## DBaldock9

Bosk said:


> I've performed the wire mod, severing all PCB traces from the 3.5mm input jack to the potentiometer, to the Z-foil resistors, to the input caps, and then to the op-amps.
> I replaced them with hand-cut lengths of 26AWG 4N OCC silver wire, and used 4% silver solder on those joints. (first time using lead-free solder, i miss the shiny joints of 60/40)
> 
> The sonic difference is _enormous_. Early last night after performing the mod the amp was almost unlistenable, possibly because the solder joints were breaking in, the extra detail had a slight metallic ringing and was so fatiguing I could barely tolerate it. It has already settled in this morning -or my brain has adjusted to what I'm hearing- and is sounding much better. Still a touch on the cold side, but the added magnification of the very tiniest of details is extremely obvious and bass & dynamics have improved too. The amp is also noticably louder at the same position on the volume wheel, significantly so.
> ...



For some reason (probably due to knowing that the tubes can't directly drive the outputs), I thought the signal path was:

3.5mm TRS Input -> Input Potentiometer -> Tubes -> Capacitors -> Op-Amps -> Output Jacks (3.5mm TRS / 2.5mm TRRS)


----------



## Bosk

DBaldock9 said:


> For some reason (probably due to knowing that the tubes can't directly drive the outputs), I thought the signal path was:
> 
> 3.5mm TRS Input -> Input Potentiometer -> Tubes -> Capacitors -> Op-Amps -> Output Jacks (3.5mm TRS / 2.5mm TRRS)


I traced the path carefully and it runs from the 3.5mm jack to the volume pot, down to the 2.2k resistors (the original Dales may have been 2.5k but underneath them in the PCB those slots are marked 2.2k), up to the closest set of Wima caps, then down to the tubes.
Beyond that it gets difficult to follow so those are all I replaced, but I may just replace everything leading to the 2.5mm jack even though the signal seems to be routed through the relay. I’ve been wondering if that’s there just to quieten the turn-on thud and if it could be safely removed.


----------



## DBaldock9

Bosk said:


> I traced the path carefully and it runs from the 3.5mm jack to the volume pot, down to the 2.2k resistors (the original Dales may have been 2.5k but underneath them in the PCB those slots are marked 2.2k), up to the closest set of Wima caps, then down to the tubes.
> Beyond that it gets difficult to follow so those are all I replaced, but I may just replace everything leading to the 2.5mm jack even though the signal seems to be routed through the relay. I’ve been wondering if that’s there just to quieten the turn-on thud and if it could be safely removed.



If we're still talking about the B4-X, the only relay I know about is the one that switches off the power to the amplifier circuit, and routes it to the battery, when the charger is plugged in.


----------



## Bosk

DBaldock9 said:


> If we're still talking about the B4-X, the only relay I know about is the one that switches off the power to the amplifier circuit, and routes it to the battery, when the charger is plugged in.


Oh. That isn't a relay sitting next to the 2.5mm output? Whatever it is it looks like the output is being routed through it.


----------



## Bosk

I severed the traces to & from the second set of WIMA caps and took a photo of how the board looks now. Those large leads are from the Z-foil resistors in case I ever want to put use them in a different piece of gear.


----------



## DBaldock9

Bosk said:


> Oh. That isn't a relay sitting next to the 2.5mm output? Whatever it is it looks like the output is being routed through it.



Your B4-X is different than mine - there's no relay up in the audio circuit of mine -
.


----------



## Bosk

DBaldock9 said:


> Your B4-X is different than mine - there's no relay up in the audio circuit of mine -
> .


How unusual! That may be why Douk have refused my requests for a schematic, because they know there are multiple versions and it would lead to confusion. 

Does your 2.5mm jack receive its' left and right signal direct from the 3.5mm jack next to it then?


----------



## DBaldock9

Bosk said:


> How unusual! That may be why Douk have refused my requests for a schematic, because they know there are multiple versions and it would lead to confusion.
> 
> Does your 2.5mm jack receive its' left and right signal direct from the 3.5mm jack next to it then?



The only way that the B4-X could have a truly balanced output, is for channels "A" & "B" of op-amp 1 to be driving the L+ & L- pins of the 2.5mm jack; and for channels "A" & "B" of op-amp 2 to be driving the R+ & R- pins.  So, only the L+ & R+ signals should be common between the 3.5mm TRS and the 2.5mm TRRS jacks.

I'm currently traveling for my Christmas holiday (was On-Call at work during Christmas & New Year's weeks).
Don't have an Ohmmeter with me, so I'll have to check the circuits sometime after the 16th (when I expect to get back home).

Can you tell where the signal is coming from, that they're using to drive the audio circuit relay?
The B4-X was a "dumb" amp, with the only smarts being that when +12Vdc was applied to the charging input, the 12Vdc supply to the voltage inverters/boosters was switched off by the relay, so that the battery would charge, instead.


----------



## Bosk

DBaldock9 said:


> The only way that the B4-X could have a truly balanced output, is for channels "A" & "B" of op-amp 1 to be driving the L+ & L- pins of the 2.5mm jack; and for channels "A" & "B" of op-amp 2 to be driving the R+ & R- pins.  So, only the L+ & R+ signals should be common between the 3.5mm TRS and the 2.5mm TRRS jacks.
> 
> I'm currently traveling for my Christmas holiday (was On-Call at work during Christmas & New Year's weeks).
> Don't have an Ohmmeter with me, so I'll have to check the circuits sometime after the 16th (when I expect to get back home).
> ...


Ahh yes of course you're right, I forgot about the balanced aspect.

To be honest -and this seems a little ridiculous- I've found it very difficult to follow the signal path from the op-amps & tubes to the 2.5mm jack without a schematic. The traces cover both sides of the board and its quite confusing.

Here are photos of how my second B4-X looks right now for reference. Note the black hook-up wire on the underside actually came with the stock amp, I'm guessing that particular trace must be faulty so they did a manual fix.


----------



## DBaldock9

Bosk said:


> Ahh yes of course you're right, I forgot about the balanced aspect.
> 
> To be honest -and this seems a little ridiculous- I've found it very difficult to follow the signal path from the op-amps & tubes to the 2.5mm jack without a schematic. The traces cover both sides of the board and its quite confusing.
> 
> Here are photos of how my second B4-X looks right now for reference. Note the black hook-up wire on the underside actually came with the stock amp, I'm guessing that particular trace must be faulty so they did a manual fix.



Are those the stock tube carrier boards, or some that you created?
Can you read on your tubes, whether they're still using P/N: JAN5899?

I can see that there have been some significant board layout changes, between my B4-X and yours.
They added the relay in the audio circuit of yours, with the diode & transistor probably driving it.
Mine has 8-Pin tube carrier connections, and yours has 6-pins (they only use 6 of the pins on the tubes).
My tube carriers are further from the sockets, giving more space for discrete op-amps - like the SS3602.
.
I did find a Spec Sheet for the +12V to ±12V converters, and they're only rated for a maximum of ±42mA output - so installing high current op-amps is a waste of effort.
.
https://52ebad10ee97eea25d5e-d7d408...f3.rackcdn.com/UK_Z03-Mornsun_PSU00371_DS.pdf


----------



## Bosk

Those tube boards are stock, I haven't touched them. The tubes actually read Raytheon JAN 5784 WB.

Do you think there'd be any downside to removing that relay, diode & transistor in the audio section? Also when you refer to high current op-amps I'm not sure what you mean - alternatives to the Bursons perhaps? I've read about the SS3602s, Sparkos sell some interesting-looking super regulators too.


----------



## DBaldock9 (Jan 10, 2021)

*Begin EDIT:  *It's interesting - if they've switched to using JAN5784WB tubes - to see that all of the sites where I see the B4-X listed, still make reference to it using JAN5899 tubes. Where did you buy your B4-X, and did the sales info list it as having JAN5899 or JAN5784WB tubes?  *:End EDIT*

The JAN5899 tubes have a circular pin grid, and it looks like the JAN5784WB tubes have a flat pin grid - or do they actually stick out of the bottom of the tube in a circular arrangement?

It might be a good idea to plug any earphones into the amp, after it's had a bit of time to warm up, if you're going to remove the "protection" relay.  Just make sure you short across the correct pairs of signal contacts, once the relay is out.

As far as high current op-amps -
For instance, the OPA-1622 specs say: This device also has a high output-drive capability of +145mA / –130 mA.
And the AD-8397-ARZ specs say: High linear output current 310 mA peak into 32 Ω on ±12 V supplies while maintaining −80 dBc SFDR.
.
My point is that with the A1212S/D-1W converters (one per channel) only producing a max of ±42mA - it doesn't make sense to put op-amps rated for hundreds of mA in the B4-X.  If there's a fairly large bank of capacitors on both sets of ±12VDC rails, then the op-amps could deliver higher peaks, but the average will be limited to what the converters supply.


----------



## Bosk

DBaldock9 said:


> *Begin EDIT:  *It's interesting - if they've switched to using JAN5784WB tubes - to see that all of the sites where I see the B4-X listed, still make reference to it using JAN5899 tubes. Where did you buy your B4-X, and did the sales info list it as having JAN5899 or JAN5784WB tubes?  *:End EDIT*
> 
> The JAN5899 tubes have a circular pin grid, and it looks like the JAN5784WB tubes have a flat pin grid - or do they actually stick out of the bottom of the tube in a circular arrangement?
> 
> ...


I purchased both of my B4-X's from (I hope?) Douk's official Ebay store. Perhaps limited availablity of 5899's forced them to switch? Nice catch, technically its false advertising.
https://www.ebay.com.au/itm/Mini-Po...038057?hash=item5b7dc442a9:g:mk0AAOSwQSBfaFGQ

It'd be interesting to experiment with removing the relay but I heed your warning about warm up first, that's a mod I'll give a bit more thought to.

That's an interesting point you make about the op-amps. It wouldn't be too difficult to replace those converters, but are you suggesting using higher-current op-amps would improve tsound quality or merely increase the output power? In any event I'm assuming that would increase battery drain significantly so it sounds like it would effectively necessitate ditching the existing case as the 1000mAh battery wouldn't last long at all. Despite reservations I'm not opposed to going completely new-case on my main B4-X, the other I plan to mod to a much lesser extent and keep in the original case.


----------



## DBaldock9

Bosk said:


> I purchased both of my B4-X's from (I hope?) Douk's official Ebay store. Perhaps limited availablity of 5899's forced them to switch? Nice catch, technically its false advertising.
> https://www.ebay.com.au/itm/Mini-Po...038057?hash=item5b7dc442a9:g:mk0AAOSwQSBfaFGQ
> 
> It'd be interesting to experiment with removing the relay but I heed your warning about warm up first, that's a mod I'll give a bit more thought to.
> ...



It's interesting to see that, in less than 1 year, the number of JAN5899 listings on eBay has gone from "a lot", down to just a few.  Since these tubes were designed in the 1950s, and probably haven't been made for 30 or more years, I guess the *N*ew *O*ld *S*tock of tubes is nearly depleted.  

I think I'm going to buy a few more spares, before they're no longer available.

If you compare the Spec Sheets for the JAN5899 (UHF Radio Tube) and JAN5784WA (VHF Radio Tube), you'll see that they've got different pin-outs, as well as different DC operational values (Plate, Grid, & Heater Current; and Cathode Resistance).  This means that they probably can't be swapped in the same circuit, without changing other components (mainly resistor values).  I'd guess that if I measure all of the resistors for the tube-part of the circuit in my B4-X, they should be different than the ones in your B4-X --- unless they're operating the tubes in such a non-standard mode, that it just doesn't make any difference.  
.
JAN5899 - https://frank.pocnet.net/sheets/138/5/5899.pdf
JAN5784WA - https://frank.pocnet.net/sheets/138/5/5784WB.pdf


----------



## Bosk

DBaldock9 said:


> It's interesting to see that, in less than 1 year, the number of JAN5899 listings on eBay has gone from "a lot", down to just a few.  Since these tubes were designed in the 1950s, and probably haven't been made for 30 or more years, I guess the *N*ew *O*ld *S*tock of tubes is nearly depleted.
> 
> I think I'm going to buy a few more spares, before they're no longer available.
> 
> ...


This has certainly added a layer of intrigue to our B4-X journies. For NOS tubes made (or at least conceived) in the 50s its remarkable to me the 5899s are as cheap as they are. I own a pair of EL84 & 6L6GC speaker power amps and would almost need to sever a leg to kit them out in vintage American or Western European NOS tubes. Buying some 5899 spares probably can't hurt.

I did notice after removing the Dale resistors that many of them weren't the exact values labeled on the PCB, but am not sure if that has anything to do with PCB version revisions. It could simply be they changed suppliers and Dales were available in bulk in the exact values they needed. So by measuring your resistors if you planned to replace them you may actually get a different picture of what you really need as there's no guarantee those values match up with the original intentions of the designer.

Anecdotally, entry-level Chinese audio gear often seems to follow similar patterns of cost-cutting, incorrect specs, inconsistent parts substitutes and the like. The upside of which is more potential scope for improvement for intrepid DIYers.


----------



## yoyodunno

Does anyone know if the muses02 opamps on aliexpress are authentic? I'm looking to get it from this store: https://www.aliexpress.com/item/100...earchweb0_0,searchweb201602_,searchweb201603_ The picture looks the same as the one on the official njr site https://www.njr.com/MUSES/series/MUSES02.html


----------



## Hal Rockwell

yoyodunno said:


> Does anyone know if the muses02 opamps on aliexpress are authentic? I'm looking to get it from this store: https://www.aliexpress.com/item/100...earchweb0_0,searchweb201602_,searchweb201603_ The picture looks the same as the one on the official njr site https://www.njr.com/MUSES/series/MUSES02.html



I doubt those are original MUSES. Considering that the price of the originals on Mouser is 46$ for a single opamp, 7$ for two seams just not logical.


----------



## Bosk

Ebay is famous for counterfeit parts, I'm not sure about Aliexpress but wouldn't be shocked if its the same. Generally the rule is to buy from an authorized dealer or assume if something's seems too good to be true it probably is. It wouldn't surprise me to learn the B4-X itself is built with counterfeit parts, the Dale resistors & Wima caps for instance.


----------



## elvispreasley (Jan 19, 2021)

Just got my B4-x. Unfortunately it appears to be from the new batch with a different type of tubes. Unluckily I spent about 40$ on few different pairs of 5899 tubes, thinking to make it replacable on my amp) Well, hope someday I'll find out what to do with them...
The amp came with 2 Burnson V5i op amps (which I also ordered), so I installed them right away. Also I covered the inner part of the amp metal body with faradey tape and put 2 silicone rings on each tubes. Another words, did some basic mod straight out of the box.
I still need more time to realize - do I like the sound with this amp better then with the built in amp of my portable multibit dac/amp (Tento 1866), but I already have one concern. The amp has very noticeable "hiss" noise on the background. When the music is playing it's kinda hard to hear it, so it's not really affecting a lot the overall sound of the amp during this time, but when the music is not playing - the "hiss" noise is really easy to hear. I do have an experience with several tube and hybrid amps, but never ever heard anything like this, as they usually had quite black background. Is this a typical situation with B4-x or my particular amp has some problem, which cause this effect? If there any chance to fix it?

UPD: Just found out that the hiss exists only with low impedance and high sensitivity earbuds/earphones (32 ohm, 115db as a particular example). With 600ohm earbuds, B4-x has fairly black background.


----------



## Bosk

elvispreasley said:


> Just got my B4-x. Unfortunately it appears to be from the new batch with a different type of tubes. Unluckily I spent about 40$ on few different pairs of 5899 tubes, thinking to make it replacable on my amp) Well, hope someday I'll find out what to do with them...
> The amp came with 2 Burnson V5i op amps (which I also ordered), so I installed them right away. Also I covered the inner part of the amp metal body with faradey tape and put 2 silicone rings on each tubes. Another words, did some basic mod straight out of the box.
> I still need more time to realize - do I like the sound with this amp better then with the built in amp of my portable multibit dac/amp (Tento 1866), but I already have one concern. The amp has very noticeable "hiss" noise on the background. When the music is playing it's kinda hard to hear it, so it's not really affecting a lot the overall sound of the amp during this time, but when the music is not playing - the "hiss" noise is really easy to hear. I do have an experience with several tube and hybrid amps, but never ever heard anything like this, as they usually had quite black background. Is this a typical situation with B4-x or my particular amp has some problem, which cause this effect? If there any chance to fix it?
> 
> UPD: Just found out that the hiss exists only with low impedance and high sensitivity earbuds/earphones (32 ohm, 115db as a particular example). With 600ohm earbuds, B4-x has fairly black background.


Yes I found there's a huge amount of background electrical noise with the stock amp, which is its' Achilles heel along with poor battery life.

In my case replacing all the stock Dale resistors removed almost all the noise. There's still a little but its so quiet I barely notice it at all.


----------



## elvispreasley

Bosk said:


> Yes I found there's a huge amount of background electrical noise with the stock amp, which is its' Achilles heel along with poor battery life.
> 
> In my case replacing all the stock Dale resistors removed almost all the noise. There's still a little but its so quiet I barely notice it at all.



Are you sure that replacing of the stock resistors  - affecting the noise? I mean, it seems like it's all because of the high output impedance of the amplifier,  as with high impedance headphones - there is no noise whatsoever. Just don't understand - how the resistors may affect it in such a case?

Meantime, I compared the sound of the build in amp of my Tento 1866 with B4-x and can say for sure that Little Bear significantly improves SQ of my dac/amp. First of all it gives higher volume level, pairing with hard to drive earbuds and cans (like my LCD3). Also it gives more clarity and transparency for the sound, more bass slam and better LF control. The soundstage feel bigger and more airy.
I'm really happy with a performance of this little cheap guy and can highly recomend it for any portable setup. Great performance for such a small money.


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## Bosk

elvispreasley said:


> Are you sure that replacing of the stock resistors  - affecting the noise? I mean, it seems like it's all because of the high output impedance of the amplifier,  as with high impedance headphones - there is no noise whatsoever. Just don't understand - how the resistors may affect it in such a case?
> 
> Meantime, I compared the sound of the build in amp of my Tento 1866 with B4-x and can say for sure that Little Bear significantly improves SQ of my dac/amp. First of all it gives higher volume level, pairing with hard to drive earbuds and cans (like my LCD3). Also it gives more clarity and transparency for the sound, more bass slam and better LF control. The soundstage feel bigger and more airy.
> I'm really happy with a performance of this little cheap guy and can highly recomend it for any portable setup. Great performance for such a small money.


Unfortunately I performed a bunch of mods around the same time - replacing the battery, replacing the electrolytic caps and replacing the resistors. It felt like replacing the resistors had the biggest effect on background noise levels, but all three mods may have contributed. There is still noise remaining but at such a low level it is difficult to noticed especially when playing music.

I like your setup! The B4-X is great value but I feel value goes up exponentially when a few simple changes are made. Once noise levels are reduced & battery life improved it feels like a different product, and when modded to the extent of mine it sounds like an entirely different beast that I've no doubt can compete with _any _portable amp available.


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## elvispreasley

Bosk said:


> Unfortunately I performed a bunch of mods around the same time - replacing the battery, replacing the electrolytic caps and replacing the resistors. It felt like replacing the resistors had the biggest effect on background noise levels, but all three mods may have contributed. There is still noise remaining but at such a low level it is difficult to noticed especially when playing music.
> 
> I like your setup! The B4-X is great value but I feel value goes up exponentially when a few simple changes are made. Once noise levels are reduced & battery life improved it feels like a different product, and when modded to the extent of mine it sounds like an entirely different beast that I've no doubt can compete with _any _portable amp available.




What kind of battery did you replace on? How long it holds charge now?


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## Bosk

elvispreasley said:


> What kind of battery did you replace on? How long it holds charge now?


I replaced the stock 1,000mAh battery with one that's 5,500 mAh, and recently took delivery of another that's 10,000 mAh. I haven't timed battery life since, but am guessing it would be 5 or 6 hours as the other mods I've done like changing the op-amps for Burson v6s and installing larger capacitors has increased the battery drain.


----------



## elvispreasley

Bosk said:


> I replaced the stock 1,000mAh battery with one that's 5,500 mAh, and recently took delivery of another that's 10,000 mAh. I haven't timed battery life since, but am guessing it would be 5 or 6 hours as the other mods I've done like changing the op-amps for Burson v6s and installing larger capacitors has increased the battery drain.



5-6 hours is not really far from the stock 4 hours battery life, but if your mods are draining a lot of power - that's a great result!
What about the size of the battery? Does it fits inside of the B4-x, like the stock one or it stays outside - "powerbank style"?


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## Bosk

elvispreasley said:


> 5-6 hours is not really far from the stock 4 hours battery life, but if your mods are draining a lot of power - that's a great result!
> What about the size of the battery? Does it fits inside of the B4-x, like the stock one or it stays outside - "powerbank style"?


The 5,500 mAh battery is slightly smaller than the stock B4-X itself, whereas the 10,000 mAh battery is much larger and about twice as heavy. I'll post more photos of the amp here when I next mod it further.


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## elvispreasley

Bosk said:


> The 5,500 mAh battery is slightly smaller than the stock B4-X itself, whereas the 10,000 mAh battery is much larger and about twice as heavy. I'll post more photos of the amp here when I next mod it further.



You mean that 5500 battery is almost the size of whole B4-X?


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## Bosk

elvispreasley said:


> You mean that 5500 battery is almost the size of whole B4-X?


That's right, here's a photo of it under my amp that I posted earlier in the thread.


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## elvispreasley

Bosk said:


> That's right, here's a photo of it under my amp that I posted earlier in the thread.



Oh yeh, I've seen this picture, but didn't realize that there is a battery underneath the amp.
That's to extreme to me, to be honest. I'll rather stay with 4 hours battery life, but in a compact form factor)
However I'm saluting to your effort - to push the SQ of B4-x far beyond it's stock limit!


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## DBaldock9

I've ordered a set of 8 spare JAN5899 tubes, and some of the 8-Pin miniature tube sockets.

Depending on how difficult it is to get the necessary power supply components, I'm going to give a shot at building a Balanced (4x tubes & 4x op-amps) Amp, based on the B4-X circuit design. 
. 
Wish I had access to an easy to use circuit board layout program, and an inexpensive board fab shop.


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## Bosk

DBaldock9 said:


> I've ordered a set of 8 spare JAN5899 tubes, and some of the 8-Pin miniature tube sockets.
> 
> Depending on how difficult it is to get the necessary power supply components, I'm going to give a shot at building a Balanced (4x tubes & 4x op-amps) Amp, based on the B4-X circuit design.
> .
> Wish I had access to an easy to use circuit board layout program, and an inexpensive board fab shop.


That sounds awesome!

It’s a very ambitious mod, are also you planning to design a new power supply, perhaps with separate voltage regulation for each tube & op-amp? I do wonder how much untapped potential lies with cleaner power, especially if you plan on running it on mains power perhaps.

I can’t wait to watch your progress.


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## DBaldock9

Bosk said:


> That sounds awesome!
> 
> It’s a very ambitious mod, are also you planning to design a new power supply, perhaps with separate voltage regulation for each tube & op-amp? I do wonder how much untapped potential lies with cleaner power, especially if you plan on running it on mains power perhaps.
> 
> I can’t wait to watch your progress.



Rather than a mod to my current B4-X - I really want to design a new circuit board, with enough space for the 4x tubes, and clearance around the op-amp sockets for large discrete op-amps.  I've got to figure out whether the circuit will require manual switches, to change between Balanced & Single-Ended Input modes.

I was thinking I might use one or two of these 12,500mAH 3.7V batteries - https://www.aliexpress.com/item/33049806489.html
One of these 5V USB chargers / boost modules could provide the power supply input - https://www.amazon.com/daier-Lithium-Li-ion-Battery-Charger/dp/B07SBZZ5SC/
It can also take the 3.7V from the battery, and output a (+) voltage from 4.3V to 27V, at up to 2A.
I'm wondering whether the boost module can be used "floating", so it can provide the (-) voltage rail, as well?


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## Bosk

DBaldock9 said:


> Rather than a mod to my current B4-X - I really want to design a new circuit board, with enough space for the 4x tubes, and clearance around the op-amp sockets for large discrete op-amps.  I've got to figure out whether the circuit will require manual switches, to change between Balanced & Single-Ended Input modes.
> 
> I was thinking I might use one or two of these 12,500mAH 3.7V batteries - https://www.aliexpress.com/item/33049806489.html
> One of these 5V USB chargers / boost modules could provide the power supply input - https://www.amazon.com/daier-Lithium-Li-ion-Battery-Charger/dp/B07SBZZ5SC/
> ...


So you'd effectively be building a new amplifier from scratch. Those batteries are certainly very cheap for the amount of power they'd provide, and you'll certainly need quite a bit depending on how much run time you'd be happy with. 

Wouldn't you obtain optimum performance by effectively building an entirely separate power supply for each op-amp & tube? Of course that would mean much more space required and power drawn which would could be a consideration depending if plan to build something geuinely portable or more in the transportable category.


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## Bosk

Speaking of mods! I just finished replacing the silver wire I'd used to bypass the traces on my B4-X. This time I used pure 99% silver / 1% gold wire from CEMA, with two cores instead of one. I also re-did all the solder joints with WBT silver solder.

Its too early to give a concrete verdict but my initial impression is one of  improved smoothness, which is what I wanted as the pure silver wire made the amp sound too analytical & cold, though insanely detailed. I'm already noticing much more groove factor & less fatigue, though less perception of detail.


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## elvispreasley

Meantime,  more impressions about B-4x v2 (with new tubes). 
Reading this thread I found several cases, where the owners claiming about extreme microphone effect of the built in tubes, which cause buzzing sounds even with small touching of the amp. Can say with 100% guarantee,  that new B4-x with 2 silicone o-rings on each tube, had ZERO microphone effect - no matter how you touching or shaking the amp!
Updated information about hiss. The hiss itself become far less after about 10 hours of burn-in and appears only with high sensitive earphones, which is tipical even with much more expensive amplifier (like Alo CDM) for example.
I found that B4-x is sensitive to the Wi-Fi signal interference, when you're keeping the device with switched on Wi-Fi, really close to the amp (please, check the attached pictures of the case - when the interference starts to cause a noise in the background), even after I covered the inner part of the amp metal body with Faradei tape. It feels like the "week spot" is the window of the amp, as after I did cover it with a piece of foil - problem gone completely. 
One more thing I really like about this amp - is its heat level. The amp become slightly warm even after 4 hours of the constant usage. I used to have Alo CDM sometime ago and it became REALLY HOT after about half an hour of usage, so you simply can't stack it with any other device, like I do it with B4-x.
Overall I really like the performance of this amplifier and honestly thinking that this is almost a steal deal for the price under 100$.


----------



## povidlo

elvispreasley said:


> Meantime,  more impressions about B-4x v2 (with new tubes).
> Reading this thread I found several cases, where the owners claiming about extreme microphone effect of the built in tubes, which cause buzzing sounds even with small touching of the amp. Can say with 100% guarantee,  that new B4-x with 2 silicone o-rings on each tube, had ZERO microphone effect - no matter how you touching or shaking the amp!
> Updated information about hiss. The hiss itself become far less after about 10 hours of burn-in and appears only with high sensitive earphones, which is tipical even with much more expensive amplifier (like Alo CDM) for example.
> I found that B4-x is sensitive to the Wi-Fi signal interference, when you're keeping the device with switched on Wi-Fi, really close to the amp (please, check the attached pictures of the case - when the interference starts to cause a noise in the background), even after I covered the inner part of the amp metal body with Faradei tape. It feels like the "week spot" is the window of the amp, as after I did cover it with a piece of foil - problem gone completely.
> ...


Can you please confirm the size of o-rings you're using? Do the tubes have to be removed to apply the o-rings?


----------



## elvispreasley

povidlo said:


> Can you please confirm the size of o-rings you're using? Do the tubes have to be removed to apply the o-rings?



This is the o-rings that I'm using and no - you don't need to remove the tubes to put them on)

https://www.ebay.com/itm/US-Stock-Q...-/372397085535?_trksid=p2349624.m46890.l49292


----------



## Mouseman

povidlo said:


> Can you please confirm the size of o-rings you're using? Do the tubes have to be removed to apply the o-rings?


15mm OD/8mm ID ones are the size that was recommended previously. They work without removing the tubes (which you can't do anyway, they're soldered in). You just have to _gently _bend them up a bit and then roll or slide the o-rings on. It worked better for me if I stretched them before trying to fit them.


----------



## alvaroenoht (Jan 24, 2021)

elvispreasley said:


> Meantime,  more impressions about B-4x v2 (with new tubes).
> Reading this thread I found several cases, where the owners claiming about extreme microphone effect of the built in tubes, which cause buzzing sounds even with small touching of the amp. Can say with 100% guarantee,  that new B4-x with 2 silicone o-rings on each tube, had ZERO microphone effect - no matter how you touching or shaking the amp!
> Updated information about hiss. The hiss itself become far less after about 10 hours of burn-in and appears only with high sensitive earphones, which is tipical even with much more expensive amplifier (like Alo CDM) for example.
> I found that B4-x is sensitive to the Wi-Fi signal interference, when you're keeping the device with switched on Wi-Fi, really close to the amp (please, check the attached pictures of the case - when the interference starts to cause a noise in the background), even after I covered the inner part of the amp metal body with Faradei tape. It feels like the "week spot" is the window of the amp, as after I did cover it with a piece of foil - problem gone completely.
> ...


I got the new model as well with the new tubes, but I find the sound coming from it rather thin. The major changes I notice are in the treble, but nothing if worse in the low end. it also came with a major imbalance, that I havent adjusted yet. Anything past 12 o'clock is mayor distortion.  Any suggestions??


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## elvispreasley (Jan 24, 2021)

alvaroenoht said:


> I got the new model as well with the new tubes, but I find the sound coming from it rather thin. The major changes I notice are in the treble, but nothing if worse in the low end. it also came with a major imbalance, that I havent adjusted yet. Anything past 12 o'clock is mayor distortion.  Any suggestions??



In my case the quality and the amount of the low end, was the biggest difference compare to the built in amp of my dac/amp. Also I found great changes in overall clarity and transparency of the sound, with B4-x.
However, I never listened it with a stock op-amps, as I did replace them immediately, after I took B4-x out of the box, with Burson V5i. So I think that this what may cause a major difference in my case.
Also, I didn't compare much the sound change with B4-x, paired with some iems, as I'm listening mostly hard to drive earbuds and planar cans with it.  Maybe there is not much changes with easy to drive iems, but with tough units - the difference is more then substantial.


----------



## alvaroenoht

elvispreasley said:


> In my case the quality and the amount of the low end, was the biggest difference compare to the built in amp of my dac/amp. Also I found great changes in overall clarity and transparency of the sound, with B4-x.
> However, I never listened it with a stock op-amps, as I did replace them immediately, after I took B4-x out of the box, with Burson V5i. So I think that this what may cause a major difference in my case.
> Also, I didn't compare much the sound change with B4-x, paired with some iems, as I'm listening mostly hard to drive earbuds and planar cans with it.  Maybe there is not much changes with easy to drive iems, but with tough units - the difference is more then substantial.


I purchased some high current opamp, but havent recieved then yet. I was hesitant to buy the bursons because they were just too expensive.  Did you have to adjust the trim pots to balance them or it came good from the factory?. I also noticed that one tube glows signifcantly more than the other.


----------



## DBaldock9

alvaroenoht said:


> I purchased some high current opamp, but havent recieved then yet. I was hesitant to buy the bursons because they were just too expensive.  Did you have to adjust the trim pots to balance them or it came good from the factory?. I also noticed that one tube glows signifcantly more than the other.



I've also tried a few different higher current op-amps - but then, after reading the spec sheet for the Mornsun +12V to ±12V converters -

https://52ebad10ee97eea25d5e-d7d408...f3.rackcdn.com/UK_Z03-Mornsun_PSU00371_DS.pdf

- and seeing that they're rated for only ±42mA, I realized that using op-amps that are rated for much more than 50mA (continuous), won't be able to deliver their higher current output to the headphones.  It's true that peak current can be higher, due to the capacitors on the ±12V rails, but continuous output current is limited by the converters.


----------



## elvispreasley

alvaroenoht said:


> I purchased some high current opamp, but havent recieved then yet. I was hesitant to buy the bursons because they were just too expensive.  Did you have to adjust the trim pots to balance them or it came good from the factory?. I also noticed that one tube glows signifcantly more than the other.



In my case no need to do any trim adjustment with V5i, as both channels were pretty balanced to my ears.


----------



## Bosk (Jan 25, 2021)

elvispreasley said:


> In my case the quality and the amount of the low end, was the biggest difference compare to the built in amp of my dac/amp. Also I found great changes in overall clarity and transparency of the sound, with B4-x.
> However, I never listened it with a stock op-amps, as I did replace them immediately, after I took B4-x out of the box, with Burson V5i. So I think that this what may cause a major difference in my case.
> Also, I didn't compare much the sound change with B4-x, paired with some iems, as I'm listening mostly hard to drive earbuds and planar cans with it.  Maybe there is not much changes with easy to drive iems, but with tough units - the difference is more then substantial.


In case you're interested I did find the V6s to be a significant step up from the V5is. However they draw more power and require the removal of the glass window or the amp to be run without top case.

To answer the earlier question, I ran a test and the 5500 mAh battery with the V6s & much larger capacitors installed powers the amp for roughly 5.5 hours. Haven't timed the 10000 mAh battery yet.


----------



## elvispreasley

Bosk said:


> In case you're interested I did find the V6s to be a significant step up from the V5is. However they draw more power and require the removal of the glass window or the amp to be run without top case.
> 
> To answer the earlier question, I ran a test and the 5500 mAh battery with the V6s & much larger capacitors installed powers the amp for roughly 5.5 hours. Haven't timed the 10000 mAh battery yet.



Thanks for an information,  but as I said before - V6 and external battery is just to extreme for me)
However it's always good to know that there is an opportunities to push the sound of B4-x even further, if you're ok to move away from the stock compact shape.


----------



## alvaroenoht

So I decided to open my lb to adjust the channel imbalance. I noticed one of the adjustment pots is broken. It doesnt do anything for half a rotation and then volume jumps. Thats something to be improved for sure. The other side makes a cracking noise when adjusting. got it somehow balanced turning both pots to 0.

Also I noticed that the dc to dc converters are different brands. I dont know if  this affects quality, if so I think it can be improved.


----------



## Bosk

alvaroenoht said:


> So I decided to open my lb to adjust the channel imbalance. I noticed one of the adjustment pots is broken. It doesnt do anything for half a rotation and then volume jumps. Thats something to be improved for sure. The other side makes a cracking noise when adjusting. got it somehow balanced turning both pots to 0.
> 
> Also I noticed that the dc to dc converters are different brands. I dont know if  this affects quality, if so I think it can be improved.


My adjustment pots also make the crackling noise when turned past a certain point. I don't know if that indicates they're having a negative effect on power being delivered to the tubes & op-amps.

The mismatched regulators is a concern, I've no doubt performance could be improved significantly if they were replaced with multiple voltage regulation circuits and was planning to do this myself but eventually decided to keep the amp housed in the original case which lacks the room for such a major mod.


----------



## alvaroenoht

Bosk said:


> My adjustment pots also make the crackling noise when turned past a certain point. I don't know if that indicates they're having a negative effect on power being delivered to the tubes & op-amps.
> 
> The mismatched regulators is a concern, I've no doubt performance could be improved significantly if they were replaced with multiple voltage regulation circuits and was planning to do this myself but eventually decided to keep the amp housed in the original case which lacks the room for such a major mod.


I want to start replacing those pots. And perhaps get good regulators. Any idea where to get them?.  Looks like the power supply caps are smaller now¿?.


----------



## Bosk

alvaroenoht said:


> I want to start replacing those pots. And perhaps get good regulators. Any idea where to get them?.  Looks like the power supply caps are smaller now¿?.


I'm actually not sure regarding high-quality replacements for those pots but if anyone here knows where to source some I'd be interested in replacing those on my B4-X.

My stock caps were Rubycons of some sort, but its impossible to know if they were genuine or counterfeit. They looked identical to yours.


----------



## Bosk

Just thought I'd post a photo of my B4-X with my new DX300, and brand new 8-core 99% silver 1% gold CEMA interconnect with paladium-plated plugs. There's now abundant detail with neglibable fatigue, bass is a tad overpowering but I'm hoping that dies down as the new cable burns in.


----------



## alvaroenoht

Bosk said:


> Just thought I'd post a photo of my B4-X with my new DX300, and brand new 8-core 99% silver 1% gold CEMA interconnect with paladium-plated plugs. There's now abundant detail with neglibable fatigue, bass is a tad overpowering but I'm hoping that dies down as the new cable burns in.


how do you charge the battery?


----------



## Bosk

alvaroenoht said:


> how do you charge the battery?


There's a cable that plugs into the output socket of the 5500 mAh battery underneath the B4-X, the other end is soldered to the B4-X board where the stock battery was plugged in. I disconnect that cable from the battery and connect the wall plug charger in its place to charge it. Which allows me to keep a spare battery on hand.


----------



## povidlo

I'm looking at Burson V5i opamps for Little Bear B4-X.

I need 2 x Dual opamps, right?

Has anyone ordered from diyaudiostore.com, is it legitimate? It works out cheaper delivered than ordering from Burson directly.

Thanks in advance.


----------



## fabien32

povidlo said:


> I need 2 x Dual opamps, right?


Yes


povidlo said:


> diyaudiostore.com, is it legitimate?


I didn't buy from them, but from what I heard they are legitimate


----------



## Bosk (Feb 2, 2021)

Well somehow I ended up killing my backup B4-X after fooling around with the power-supply, I'm not exactly sure how. One channel is dead and it definitely wasn't an op-amp that was totalled. This is why I bought two amps I guess.

Anyway I stripped the board for parts to keep as backups for my main B4-X, and de-soldered everything. I took a photo of the stripped board which may be useful to others here as a reference. Mine was purchased this January on Ebay so it may be the most recent "revision" as the tubes are different from the earlier version.

As you can see from the PCB, its pretty difficult to tell exactly how and through what the signal reaches the output 2.5mm jack. I also suspect the output signal is going through the second set of 2.2uF film caps (why else would they be there?) but can't tell for sure. I would love to hear anyone's input on that as I'm considering replacing both sets of film caps on my main B4-X.


----------



## alvaroenoht

Bosk said:


> Well somehow I ended up killing my backup B4-X after fooling around with the power-supply, I'm not exactly sure how. One channel is dead and it definitely wasn't an op-amp that was totalled. This is why I bought two amps I guess.
> 
> Anyway I stripped the board for parts to keep as backups for my main B4-X, and de-soldered everything. I took a photo of the stripped board which may be useful to others here as a reference. Mine was purchased this January on Ebay so it may be the most recent "revision" as the tubes are different from the earlier version.
> 
> As you can see from the PCB, its pretty difficult to tell exactly how and through what the signal reaches the output 2.5mm jack. I also suspect the output signal is going through the second set of 2.2uF film caps (why else would they be there?) but can't tell for sure. I would love to hear anyone's input on that as I'm considering replacing both sets of film caps on my main B4-X.



Thank you for that photo, I just realize that the balance pots are not in the one at the side of the tubes, right channel is on the side. left channel is below the tube

Attached an overlay that shows the circuit so we can see the connections better


----------



## Bosk

alvaroenoht said:


> Thank you for that photo, I just realize that the balance pots are not in the one at the side of the tubes, right channel is on the side. left channel is below the tube
> 
> Attached an overlay that shows the circuit so we can see the connections better


Fantastic and much appreciated alvaroenoht.

I'm still slightly confused looking at the circuit, would you say the signal passes through all four 2.2uF film caps and all four 27R resistors?


----------



## alvaroenoht

Bosk said:


> Fantastic and much appreciated alvaroenoht.
> 
> I'm still slightly confused looking at the circuit, would you say the signal passes through all four 2.2uF film caps and all four 27R resistors?


yes, the they are in the input and output,, I will try to figure out the schematics... last night I adjusted the pots,, the vcc pot is for the plate current, I adjusted them and sound improved a lot!. perhaps getting a better pots can make a significant difference. ..


----------



## alvaroenoht

alvaroenoht said:


> Thank you for that photo, I just realize that the balance pots are not in the one at the side of the tubes, right channel is on the side. left channel is below the tube
> 
> Attached an overlay that shows the circuit so we can see the connections better


also noticed that the dc to dc converters are designed to be different brands,, is clearly written on the the plate golden sun and morn sun.. I wonder why they are not matched.


----------



## DBaldock9

alvaroenoht said:


> yes, the they are in the input and output,, I will try to figure out the schematics... last night I adjusted the pots,, the vcc pot is for the plate current, I adjusted them and sound improved a lot!. perhaps getting a better pots can make a significant difference. ..



Take a look back at this post, which contains a circuit diagram of the original B4 amp - 
https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-14511729
Four posts below that, there's a modified circuit, where the author put regulators on the tube heaters.

The balanced B4-X is based on original schematic, with some changes, to add the second op-amp.


----------



## Bosk

alvaroenoht said:


> yes, the they are in the input and output,, I will try to figure out the schematics... last night I adjusted the pots,, the vcc pot is for the plate current, I adjusted them and sound improved a lot!. perhaps getting a better pots can make a significant difference. ..


Thanks, in that case I will replace all four 2.2uF caps.

I'm definitely keen to replace the trimpots but don't know what to replace them with.


----------



## Bosk

Oh and just an idea I had, would it be possible to replace the 100K volume pot with two fixed resistors, one for each channel?

That way I could install resistors to provide the volume level I most commonly use on the pot (about 10 o'clock) whilst adjusting it on the DAP, and hopefully gaining a big increase in sound quality as I've read in so many places that volume pots, particularly cheap ones, are great for killing sound quality. I could install a stepped-attenuator but there's really only one volume level my pot is ever set to, two fixed resistors would be far cheaper and possibly sound better.


----------



## alvaroenoht

Bosk said:


> Oh and just an idea I had, would it be possible to replace the 100K volume pot with two fixed resistors, one for each channel?
> 
> That way I could install resistors to provide the volume level I most commonly use on the pot (about 10 o'clock) whilst adjusting it on the DAP, and hopefully gaining a big increase in sound quality as I've read in so many places that volume pots, particularly cheap ones, are great for killing sound quality. I could install a stepped-attenuator but there's really only one volume level my pot is ever set to, two fixed resistors would be far cheaper and possibly sound better.


I dont know the value of the resistors, but I read in this thread that vishay are a good brand


----------



## DBaldock9

Bosk said:


> Oh and just an idea I had, would it be possible to replace the 100K volume pot with two fixed resistors, one for each channel?
> 
> That way I could install resistors to provide the volume level I most commonly use on the pot (about 10 o'clock) whilst adjusting it on the DAP, and hopefully gaining a big increase in sound quality as I've read in so many places that volume pots, particularly cheap ones, are great for killing sound quality. I could install a stepped-attenuator but there's really only one volume level my pot is ever set to, two fixed resistors would be far cheaper and possibly sound better.



I think most modern amps have a 10K input impedance, which is a good load for a line output, as well as for an earphone output.


----------



## Bosk

DBaldock9 said:


> I think most modern amps have a 10K input impedance, which is a good load for a line output, as well as for an earphone output.


Does that mean I’d need to substitute the volume pot with two 10k resistors, or could I say measure the resistance of the pot when set to my typical listening position and use two resistors of that value?

sorry if that’s an awkward way of wording the question, bottom line is I’m happy to do some experimenting providing it doesn’t blow up another B4-X. ☺️


----------



## DBaldock9

Bosk said:


> Does that mean I’d need to substitute the volume pot with two 10k resistors, or could I say measure the resistance of the pot when set to my typical listening position and use two resistors of that value?
> 
> sorry if that’s an awkward way of wording the question, bottom line is I’m happy to do some experimenting providing it doesn’t blow up another B4-X. ☺



Since the Input potentiometer is isolated from the rest of the circuit with a capacitor - you can replace it with two resistors that equal the values you measure across the pot.
I guess if they're using a 100K pot, the DC input resistance (R1 + R2) = 100K.
Pin 1  (Input)
\
R1 = ?
/
Pin 2  (Wiper - to Coupling Cap and Tube Input)
\
R2 = ?
/
Pin 3  (GND)


----------



## Bosk

DBaldock9 said:


> Since the Input potentiometer is isolated from the rest of the circuit with a capacitor - you can replace it with two resistors that equal the values you measure across the pot.
> I guess if they're using a 100K pot, the DC input resistance (R1 + R2) = 100K.
> Pin 1  (Input)
> \
> ...


Ahhhhh so the sum of the two resistors should equal the value of the pot then, thanks for that. 

I might buy some cheap resistors to experiment, and if all goes well then replace them with Z-foils. I can't imagine any stepped attenuator let alone potentiometer being able to match that sound quality, and all the high-end attenuators are worth far more than the stock amp itself. Happy to make do without the convenience if it means a more pristine signal for those spectacular Tidal MQAs.


----------



## Bosk

The mod has been performed!

I wanted to test it out before buying any expensive resistors and so purchased some 8k metal film resistors from my local electronics shop. They sell mostly Chinese junk so the quality is probably bargain basement, but of the 10 I at least used the two that measured closest.

Very noticable improvement. The soundstage has opened up and feels substantially broader, imaging has also improved and detail levels have increased, yet there's less digital glare & fatigue. The amp sounds phenomonal now, my main complaint with performance was always the narrow soundstage but suddenly that's no longer an issue.

The mod does involve cutting the traces between the 3.5mm input and the potentiometer, then the traces from the potentiometer to the 2.2k input resistors, but other than that its basically soldering a resistor to two contact points - about as easy as it gets. A strongly recommended this mod as the loss of convenience is totally worth the improvement. I suspected that tiny pot was constricting the sound and its proven correct. When I replace these cheap resistors with Z-foils it should sound even better.


----------



## DBaldock9

Bosk said:


> The mod has been performed!
> 
> I wanted to test it out before buying any expensive resistors and so purchased some 8k metal film resistors from my local electronics shop. They sell mostly Chinese junk so the quality is probably bargain basement, but of the 10 I at least used the two that measured closest.
> 
> ...



Why did you need to cut traces, rather than just soldering the fixed resistors to the 3 holes for each channel of the pot?


----------



## Bosk

DBaldock9 said:


> Why did you need to cut traces, rather than just soldering the fixed resistors to the 3 holes for each channel of the pot?


The traces were already cut from the previous mod I did to replace them with silver wire. I mentioned it since unless I'm mistaken they would need to be cut if this mod were performed from scratch and the pot not removed (I've kept mine in place for now) as the signal would otherwise automatically flow through it via the traces.

Not sure if that makes sense or I'm getting confused.


On another topic, in your DIY journeys have you noticed much effect bypassing electrolytics with smaller film caps? I've done it previously and haven't noticed much change, but was thinking of doing it with all my B4-X's electrolytics.


----------



## DBaldock9

Bosk said:


> The traces were already cut from the previous mod I did to replace them with silver wire. I mentioned it since unless I'm mistaken they would need to be cut if this mod were performed from scratch and the pot not removed (I've kept mine in place for now) as the signal would otherwise automatically flow through it via the traces.
> 
> Not sure if that makes sense or I'm getting confused.
> 
> ...



I thought you were removing the pot, but if you're leaving it on the board, then some traces will have to be cut.

For the capacitors - do you mean adding film caps to both the power supply bulk caps, and the series coupling caps?


----------



## Bosk

DBaldock9 said:


> I thought you were removing the pot, but if you're leaving it on the board, then some traces will have to be cut.
> 
> For the capacitors - do you mean adding film caps to both the power supply bulk caps, and the series coupling caps?


I'm thinking of bypassing the 6x B4-X electrolytics with smaller film caps. Its a pretty common practise in DIY and I'm curious to hear your thoughts on the practise.


----------



## ledzep

Nice to see this thread still going, have I missed anything ?


----------



## elvispreasley

My "portable" setup with little bear is almost finished) Really enjoying the sound!


----------



## asatiir

elvispreasley said:


> My "portable" setup with little bear is almost finished) Really enjoying the sound!


That's a neat setup, could you give use a breakdown what is connected to what?


----------



## DBaldock9

elvispreasley said:


> My "portable" setup with little bear is almost finished) Really enjoying the sound!



Can you describe the signal path, for those of us who don't recognize the devices that you're using? Thanks!


----------



## elvispreasley (Feb 12, 2021)

Ok, let me explain you how everything works) Tento OCUB DAC/AMP working as as DAC. Then B4x connected with ALO SCX22, serving as an AMP for Tento. Then Beaglebone Black is there for digital transporting purpose, as the best transport at all (IMHO). As the Beaglebone needs to be powered with external power source - it powers from the powerbank, located on the very bottom. Also the Beaglebone need to get the internet signal with LAN cable, so it connected to the tiniest Wi-Fi router on market - Microtik mapLite  which is powering also by the powerbank. Also I'm using USB to COAX converter with galvanic isolation, which is not draining the power from the powerbank through Beaglebone like a straight USB connection (also the SQ is noticeably better with this converter).
In the end I'm getting exactly setup I love: multibit DAC with tube AMP and the oportunity to stream content with Tidal Connect and UpNP protocols,  fully powered from batteries.


----------



## Barndoor (Feb 12, 2021)

That's quite a stack.
What are the advantages of this system compared to using a small dnla capable DAP such as the Hiby R2?

Edit: just from a transport perspective - e.g. R2  - DAC - B4


----------



## elvispreasley (Feb 12, 2021)

Barndoor said:


> That's quite a stack.
> What are the advantages of this system compared to using a small dnla capable DAP such as the Hiby R2?



The short answer is - a lot.
To be more specific. I don't have an experience with R2, but used R3 as a transport before I moved on to Beaglebone and it far less convinient. First of all, R3 can't play some of the albums from Tidal. Not a lot, but the fact is still remains. Second, R3 can't play gappless with Tidal, which is pretty annoying, especially when you're listening 100+ tracks album of the trance music, where all songs creating one long composition. Third, it's tricky to navigate through your music library with such a small screen. Fourth, R3 has no MyMixes in its Tidal.
The beaglebone itself is absolutely outstanding transport even with stationary setup, so in portable it's simply unbeatable. With simple and light weight custom OS (Linux based) it shows only streaming protocols to chose from (check the attached screenshot) and can be used as an end point for Roon, streaming your local music library from Audirvana through UpNP and the most important for me - playing the music through the Tidal Connect, which streams directly from the Tidal web servers, avoiding all of the software players, codecs and everything else, which may affect SQ, despite of the bitperfect.  Also the official Tidal app might be used for navigation, which is super convenient and gives you the maximum available features.


----------



## Bosk

Perhaps I'm just imagining things, but I seemed to have noticed an improvement by wrapping my Burson V6 Vivids in copper tape to shield them.


----------



## Bosk

Quick question guys - does the grounding point next to the volume pot connect to the chassis through the pot's shaft? 

It kind of looks like it does but I just want to confirm. If it does I tend to wonder how electrically effective that connection is and if it shouldn't be enhanced....


----------



## DBaldock9

The wire from the GND point does connect the circuit board to the front panel, if the nut is tight on the Volume Control shaft. 
. 
When I was adding the capacitors to the bottom of the board, I went ahead and added an additional copper GND wire around the shaft.


----------



## Bosk

I finally finished working on my modded B4-X.  

All the resistors in the signal path are now Z-foils, the signal path wiring I replaced with pure silver litz (pain to work with), and DIYed a sort of cover to protect the op-amps & caps poking through the top of the case. I also shielded most of the components with copper tape.... not sure that did much for performance, may have had a small effect with the Burson v6s, but looks cool.

Sonically the background isn't dead quiet (I have no idea how to get this amp completely silent) and there's still the occasional very faint crackling noise, but actual performance is nothing short of superb with great dynamics, soundstage (though that's probably still a weak point vs big desktop amps), gobs of detail & musicality, everything sounds very congealed & direct. Probably being held back by my relatively inexpensive IEMs I suspect.

















Here's my other B4-X which I'm keeping in a true portable form factor.

Still working on this one, essentially its the same mods as the other B4-X except the battery isn't being replaced, the op-amps are Burson V5is instead V6s, and the Silmic IIs are a lot smaller. Performance is understandably nowhere near as good, as even the battery alone makes a big difference. Still working on it hope of getting it as close to its' big brother as possible.


----------



## Makswell

Bosk said:


> I finally finished working on my modded B4-X.
> 
> All the resistors in the signal path are now Z-foils, the signal path wiring I replaced with pure silver litz (pain to work with), and DIYed a sort of cover to protect the op-amps & caps poking through the top of the case. I also shielded most of the components with copper tape.... not sure that did much for performance, may have had a small effect with the Burson v6s, but looks cool.
> 
> ...


Your work is incredible! Looks like a factory product. I wanted to ask. Could you list all the changes made to the device in full? Have you tried to put Burson v6s into the case using an adapter - https: //www.bursonaudio.com/product/35mm-extension-lead-x-2/ , if you remove the plastic case, there should be a place for them. Or maybe you tried to put the capacitors sideways, trying to fit them inside the case?


----------



## Bosk

Makswell said:


> Your work is incredible! Looks like a factory product. I wanted to ask. Could you list all the changes made to the device in full? Have you tried to put Burson v6s into the case using an adapter - https: //www.bursonaudio.com/product/35mm-extension-lead-x-2/ , if you remove the plastic case, there should be a place for them. Or maybe you tried to put the capacitors sideways, trying to fit them inside the case?


Thanks Makswell.   

No I haven't tried fitting the V6s in the space made vacant by removing the old battery, it would be a pretty tight squeeze though and allow no leftover room for larger caps. The Silmic IIs I used definately won't fit in that space lying down but obviously smaller caps could be used instead.

From memory I performed the following mods:

Replaced op-amps with Burson V6s
Added two Wima 0.1uF film caps to each op-amp on pins 1 & 5, other end to ground
Cut signal path PCB traces, replaced them with pure silver litz wire
Replaced all audio section solder joints with Oyaide SS-47
Replaced all resistors with Vishay Z-foils & Takman Carbon films
Replaced Volume pot with two fixed Z-foil 15k resistors
Replaced 1,000 mAh stock battery with 10,000 mAh battery
Replaced electrolytics with Silmic IIs, 4x 470uF 63v & 1x 470uF 100v for the largest stock electrolytic
Created new PCB for electrolytics & connected them to stock PCB using OCC copper wire
Created braided OCC copper wire power cable
Shielded most components & stock metal case roof/floor with copper shielding tape
Superglued cut panels from spare B4-X case to fill top panel gap around op-amps
Sanded away anodized coating in all places where different parts of the case touch, to improve grounding
Added tube o-rings to reduce microphonics
Added EAR small isolation feet to bottom of the case
Added DIY top cover using cut plexiglass & hex standoffs to protect op-amps & caps


Here's another quick photo


----------



## DBaldock9

Bosk said:


> Thanks Makswell.
> 
> No I haven't tried fitting the V6s in the space made vacant by removing the old battery, it would be a pretty tight squeeze though and allow no leftover room for larger caps. The Silmic IIs I used definately won't fit in that space lying down but obviously smaller caps could be used instead.
> 
> ...



Just wondering - with the capacitors connected between the op-amp outputs and GND - doesn't that just roll off the high frequency signals? Were you having issues with oscillations?


----------



## Bosk

DBaldock9 said:


> Just wondering - with the capacitors connected between the op-amp outputs and GND - doesn't that just roll off the high frequency signals? Were you having issues with oscillations?


Perhaps I mentioned the wrong pins, I followed this guide.

https://www.bursonaudio.com/burson-ss-opamp-101-part-1-mkp-cap-tweak/


----------



## elvispreasley (Mar 17, 2021)

Moved forward from B4-x to more advanced portable tube amps and build 2 portable setups with Alo Continental V5 and Phatlab Sassy GT. Well, this is absolutely another story, I must admit. Especially with Sassy GT, which is soundind way better then my stationary hybrid tube amp.


----------



## Bosk

Yesterday I replaced the last of the signal path traces with silver litz wire in both my B4-Xs. 

I'd been putting this off because following the exact signal path as it leaves the 27R resistors is difficult. The traces start on one side of the board and finish on the other, the PCB lettering at the 2.5mm jack area is smeared so I couldn't tell which was the L+ contact, and the signal gets fed through the relay before reaching the jack. Anyway it worked, below is the correct path if anyone else wants to perform this mod. I soldered the wires on the resistor end directly to the visible portion of the 27R lead on the top side of the board, same side as the 2.5mm jack which is surface mount not through hole.

Sonically this change has been tremendous. Imaging is more stable, everything feels more relaxed yet detail levels are the same or better, and surprisingly there's even less background noise/crackle than before. Originally I was very surprised how much improvement came from replacing signal path traces with silver wire and had I performed all sections at once the difference would've been even more obvious. Considering how cheap 1m of pure silver wire is these days its possibly even better value than replacing the power supply caps, but a lot more work.

Overall my "big brother" B4-X is performing at an extremely high level now. It sounds like a very high-quality desktop amp and I tend to wonder how many off-the-shelf amps out there with a similar form factor would be capable of matching its' performance.


----------



## Muniek66

Hi guys,

will you recommend a cheap, compact Chinese tube amplifier (to work with the FiiO BTA30), to which I can connect both headphones and active speakers?

I was thinking about the following:

https://aliexpress.com/item/32675687955.html?spm=a2g0s.8937460.0.0.663d2e0eZ24DVU

https://aliexpress.com/item/32896796924.html?spm=a2g0s.8937460.0.0.663d2e0eZ24DVU

Or a bit more expensive:

https://aliexpress.com/item/1005002005882893.html?spm=a2g0s.8937460.0.0.1c302e0epDk0d6

Thanks in advance for your help.


----------



## Setmagic

I would like to share with You with my last foundling. Zishan is famous from good cheap portable DAPs. He create also super compact and ultra cheap tube amplifier AD3.

Device is not a perfect from factor but with little attention can be really impressive.



- Removed blocking output caps (big improvement)
- USB-C port with fast charging
- OPAMP replaced to OPA1612


----------



## Setmagic (Apr 26, 2021)

@edit
- changed soldering to tin-silver+pb Cardas
- replaced cheap potentiometer for paired metal DALEs resistors 0,5W <1% 14kom working in fixed 1/3 nominal gain
- caps replaced for Nichicon Fine Gold dual 100nF 25V (200nF) in analog power rail and additional small 1x 100nF + 2x22n 50V (144nF) Nichicon FW(m) Audio grade for Tube supply.


@edit
10kom works way better than 14K as resistor.


----------



## Setmagic (May 1, 2021)

Grade of quality and amount of uF in rail.
Most differences causes change this white caps on the top (left corner) to red WIMA 5% and capacity(right side) for Tube supply.
2 x220uF 63V paired with stock 100nF V50
Stock Capacitors Vs Nichicon Fine Gold.
Muses was for opamp supply just in case but do not give any improvements.


Final project ready to close in case.
Nichicon Fine Gold 50V 147uF (100+47)


----------



## povidlo

Folks, I wrote a straight-forward review for Little Bear B4-X's popular simple mod with silicone o-rings and Burson V6 Vivid opamps. 

Enjoy the read: https://www.head-fi.org/showcase/little-bear-b4-x.25234/reviews


----------



## cpu235

Just upgraded mine with Burson V5i and the soundstage is significantly wider! IMO the upgrade is worth it, the only thing I hope to improve is the clarity but for the price and portability it is nice.


----------



## triggrhaapi

cpu235 said:


> Just upgraded mine with Burson V5i and the soundstage is significantly wider! IMO the upgrade is worth it, the only thing I hope to improve is the clarity but for the price and portability it is nice.


What's your source? I am using my LG G7 and I don't have a significant change to clarity between this exact setup and my Monolith AAA dac/amp.


----------



## cpu235

triggrhaapi said:


> What's your source? I am using my LG G7 and I don't have a significant change to clarity between this exact setup and my Monolith AAA dac/amp.


I usually just pair it with my iPhone 11 or with my Fostex HPA4BL and it sounds a bit less clear but overall not huge change to clarity. But the soundstage improvement is great.


----------



## rprodrigues

@DBaldock9
Have you used the mini tube sockets you bought some time ago?


----------



## DBaldock9

rprodrigues said:


> @DBaldock9
> Have you used the mini tube sockets you bought some time ago?



No.  I've been working on other projects.


----------



## sfrsfr

Setmagic said:


> I would like to share with You with my last foundling. Zishan is famous from good cheap portable DAPs. He create also super compact and ultra cheap tube amplifier AD3.
> 
> Device is not a perfect from factor but with little attention can be really impressive.
> 
> ...


So I got the AD3 as well and it looks quite different inside. I wonder if replacing these caps improves the sound much as well...


----------



## Setmagic

sfrsfr said:


> So I got the AD3 as well and it looks quite different inside. I wonder if replacing these caps improves the sound much as well...


This is a version from 2021 it has a little better amount of capacity for tube filtering and probably better design.
There is no space as well for bigger caps, so it is hard to modify.
To bad, It's still microUSB for charging.


----------



## sfrsfr

Setmagic said:


> This is a version from 2021 it has a little better amount of capacity for tube filtering and probably better design.
> There is no space as well for bigger caps, so it is hard to modify.
> To bad, It's still microUSB for charging.


Yeah, not much space left. Maybe replacing the blue caps with gold Nichicon would have some positive effect?
The first pic is already with replaced opamp - Muses 02.


----------



## Setmagic

sfrsfr said:


> Yeah, not much space left. Maybe replacing the blue caps with gold Nichicon would have some positive effect?
> The first pic is already with replaced opamp - Muses 02.


You don't have space to replace for Nichicon Fine Gold (FG) series who is higher grade than (FW). I don't think this Panasonic is worse than generic Nichicon (FW). Main problem of previous 19/20 y versions was too small power capacitance in 30V rail for tube. For opamp you need 25v for tube at least 50V better caps are bigger and can't fit.
If you really want to try to improve filtering you can place smaller caps in parallel of this ones. Just buy Nichicon FW 2x 47uF 50V and 2x 100uF 25V. If they don't fit just make space by removing little bit of this foam from battery.
Watch out for shortcuts and polarity of caps becouse I'm sure they can explode.


----------



## sfrsfr

Setmagic said:


> You don't have space to replace for Nichicon Fine Gold (FG) series who is higher grade than (FW). I don't think this Panasonic is worse than generic Nichicon (FW). Main problem of previous 19/20 y versions was too small power capacitance in 30V rail for tube. For opamp you need 25v for tube at least 50V better caps are bigger and can't fit.
> If you really want to try to improve filtering you can place smaller caps in parallel of this ones. Just buy Nichicon FW 2x 47uF 50V and 2x 100uF 25V. If they don't fit just make space by removing little bit of this foam from battery.
> Watch out for shortcuts and polarity of caps becouse I'm sure they can explode.


What about the green Nichicon MUSE ES? Would they be a good replacement?


----------



## Light - Man

cpu235 said:


> Just upgraded mine with *Burson V5i *and the soundstage is significantly wider! IMO the upgrade is worth it, the only thing I hope to improve is the clarity but for the price and portability it is nice.


Hey guys, is there a consensus that Burson V5i is the best option that fits inside the case of the Little Bear B4?

Is the upgrade really worth the cost, delivery time and the hassle to change over the stock op-amp?

BTW, I clearly preferred the basic B4 over the B4X, when I compared both directly, but only compared them during single ended use. I also noticed that the B4X was clearly noisier.


----------



## Setmagic

sfrsfr said:


> What about the green Nichicon MUSE ES? Would they be a good replacement?


They are Bi-Polar type of electrolytic capacitor, and it's useless for that kind of application.
They just contain 2 polarized (+/-) capacitors inside one housing. Too big for a reasonable capacitance in that case.


----------



## Mouseman

Light - Man said:


> Hey guys, is there a consensus that Burson V5i is the best option that fits inside the case of the Little Bear B4?
> 
> Is the upgrade really worth the cost, delivery time and the hassle to change over the stock op-amp?
> 
> BTW, I clearly preferred the basic B4 over the B4X, when I compared both directly, but only compared them during single ended use. I also noticed that the B4X was clearly noisier.


Yes, I think it's worth the cost if you can swing it. It's not really much hassle to install at all. SQ is definitely improved over the stock units.


----------



## sfrsfr

Setmagic said:


> Grade of quality and amount of uF in rail.
> Most differences causes change this white caps on the top (left corner) to red WIMA 5% and capacity(right side) for Tube supply.
> 2 x220uF 63V paired with stock 100nF V50
> Stock Capacitors Vs Nichicon Fine Gold.
> ...


Any advice on replacing the original white caps for red WIMA 5%? Would you have a link with more info for the red WIMA 5%?
I wonder if these caps are the same in the 2021 version...


----------



## Setmagic

sfrsfr said:


> Any advice on replacing the original white caps for red WIMA 5%? Would you have a link with more info for the red WIMA 5%?
> I wonder if these caps are the same in the 2021 version...


I don't have newer version and any scheme. You can read values and replace for red WIMA in same values, but It's not necessarily right now.
I have shorted this 2 inside because they are input blocking caps, don't needed in my case.


----------



## sfrsfr

Setmagic said:


> I don't have newer version and any scheme. You can read values and replace for red WIMA in same values, but It's not necessarily right now.
> I have shorted this 2 inside because they are input blocking caps, don't needed in my case.


So are these white caps 0.22uf 63V ?
I did not find any WIMA caps with these parameters yet....
Are they same as in the previous version? (they measure about 7mm in length)


----------



## Setmagic

sfrsfr said:


> So are these white caps 0.22uf 63V ?
> I did not find any WIMA caps with these parameters yet....
> Are they same as in the previous version? (they measure about 7mm in length)


Product number MKS2C032201B00KSSD
Just copy paste and fin in Your country.
But don't expect *any* sound change.

If you really want to improve more this amp just remove this nasty potentiometer.
And replace by good resistors like DALE.
You will be adjust volume from Yours DAC device.
If You want to go deeper to modification You can replace all SMD capacitors, LDO and resistors on board for better ones, thin film resistors, original branded capacitors.


----------



## sfrsfr

Setmagic said:


> Product number MKS2C032201B00KSSD
> Just copy paste and fin in Your country.
> But don't expect *any* sound change.
> 
> ...


Thanks.
So you say the biggest improvement of the sound can be achieved by replacing the potentiometer with good resistors?


----------



## Setmagic

sfrsfr said:


> Thanks.
> So you say the biggest improvement of the sound can be achieved by replacing the potentiometer with good resistors?


Or better one than this, but it's probably not possible on this size.
I will throw input capacitors as wel but first you must find that.


----------



## Ufanco (Jan 12, 2022)

Have a question about the KAEI TAP-1S. There’s a thread on it but not many posts wondering if it’s worth buying? 
Like the option of having a power supply and battery in amp for portable use.





TAP-1 is a high-end headphone amplifier specially designed for audiophiles. It adopts a fully balanced four-channel design and supports 3.5 single-ended/4.4 balanced input and output. Use four American low-power, long-life electronic tubes as tube preamp. It adopts a desktop architecture design promoted by the OP+ discrete rear stage, with a plug-in power of up to 4900mw, and is equipped with a tube off switch function, which can be selected in two tones of normal mode and tube mode. With two flagship op amps MUSES 02, players can also achieve different timbres by changing different op amps.

Portable mode: In its battery mode, it can last about 10 hours. The battery capacity is about 5000mah, can support ordinary USB or power bank charging, and supports QC3.0, and PD protocols for fast charging.

Desktop mode: Used with an independent linear power supply, it can form a standard desktop amp. Power supply 4 sets of voltage output, external rectified and stabilized voltage directly supplied to the headphone amplifier, completely bypassing the power supply of the headphone amplifier. The dedicated aviation-grade six-core power cable realizes the power supply of the desktop-level op amp up to plus or minus 17V and the earphone discrete drive system, and the potential of this system is played out. If you use it at home or your earphones are difficult to driven, you can purchase the headphone amp.

Features:
- Four American low-power, long-life electronic tubes as tube preamp (tube can be turned off, dual tone selection)
- Air bag shock absorption technology: exclusive electronic tube suspension air shock absorption technology, effectively reducing the microphone effect
- The output thrust of plug-in mode is up to 4900MW. Tube preamp+OP+ discrete post-stage desktop amplifier architecture, easily adapt to high and low impedance, can drive various headphones of 12-600Ω
- PSU-1 power supply uses two customized single crystal copper winding transformers, filter capacitors for ELNA, HIFI capacitors for Nichicon, etc. Ultra-low noise linear regulator (LDO) is used for positive and negative power supply
- The key parts of the TAP-1 headphone amplifier are all tuned with HIFI components. Non-inductive resistors for American RA, resistors for Vishay, resistors for Philips, capacitors for WIMA, and other components for Omron, Philips, Siemens, etc. Two flagship operational amplifiers, MUSES02. With op amp seat, you can also replace dual op amp. Two 4-layer PCB boards are used inside. The headphone amplifier and the power supply are separated from each other to effectively reduce the interference of the power supply on the same board
- Repeated tuning accurate to single resistance level, audiophile grade materials regardless of cost
- Input/output compatibility: 4.4mm balanced input→3.5 single-ended output, 4.4 balanced output. 3.5mm single-ended input → 3.5 single-ended output, 4.4 single-ended output
- The linear power supply uses six-core aviation-grade gold-plated plug for Lemo 1B to output to the headphone amplifier to ensure a stable connection quality

Technical Parameters:
- Audio input: 3.5mm/4.4mm
- Audio output: 3.5mm/4.4mm
- Frequency response: 15HZ-100KHZ (±1db)
- Signal-to-noise ratio: -129DB (turn off the tube)
- Distortion: 0.004< (1KHZ, 32Ω) (turn off the tube)
- Gain: 1.65 times
- Recommended input level: >2V
- Battery life: about 10 hours in battery mode (5000mah)
- Rated power of linear power supply: 7w
- Power interface: USB TYPE-C (charging)
- 8 suffix (linear power supply 220v input)
- For Lemo 1B six-pin aviation-grade plug (wire output)
- Size: 14cm in length, 7.4cm in width and 2.9cm in height
- Recommended headphone impedance: 12-600Ω
- Recommended earphone sensitivity: less than 110DB

Maximum Output Power (L+R):
1. Battery mode (Portable mode):
Balanced               Single-Ended
3000mw (16Ω)     1200mw (16Ω)
2100mw (32Ω)     700mw (32Ω)
1100mw (100Ω)    440mw (100Ω)
450mw (300Ω)     200mw (300Ω)

2. Desktop mode:
Balanced                    Single-Ended
4900mw (16Ω)        1980mw (16Ω)
3200mw (32Ω)        1400mw (32Ω)
2000mw (100Ω)       900mw (100Ω)
990mw (300Ω)        480mw (300Ω)


----------



## DBaldock9

Ufanco said:


> Have a question about the KAEI TAP-1S. There’s a thread on it but not many posts wondering if it’s worth buying?
> Like the option of having a power supply and battery in amp for portable use.
> 
> 
> ...



That looks very interesting! 
It would be nice to have a view of the op-amp sockets - to see if there's enough space to use any of my discrete op-amps (like the Sparkos SS3602, or Burson V6).

Appears to be ~$361, with the 110V (US) Power Supply, when ordered from AliExpress.
All of the eBay vendors are somewhat more expensive - starting at around $400 (with Power Supply).

Thanks for sharing this amp!


----------



## Ufanco (Jan 12, 2022)

DBaldock9 said:


> That looks very interesting!
> It would be nice to have a view of the op-amp sockets - to see if there's enough space to use any of my discrete op-amps (like the Sparkos SS3602, or Burson V6).
> 
> Appears to be ~$361, with the 110V (US) Power Supply, when ordered from AliExpress.
> ...



There some info on it in another thread but figured up I would try here too. I recently both the Loxjie p20 based on a lot of the info you shared. Thank you posting you mods etc there. Here is pic of inside of the KAEI TAP-1S. Looks like this pic is with Burson opamp V6 series instead of the stock ones.


----------



## povidlo

Ufanco said:


> Looks like this pic is with Burson opamp V6 series instead of the stock ones.


Those are Burson v5i opamps.


----------



## DBaldock9

povidlo said:


> Those are Burson v5i opamps.



The footprint is basically the same, on the V5 & V6 - but the V6 is about 3x taller...


----------



## Ufanco

Opps must of misread what original poster said. Nice thou there easy to switch out in this unit.


----------



## DBaldock9

Ufanco said:


> There some info on it in another thread but figured up I would try here too. I recently both the Loxjie p20 based on a lot of the info you shared. Thank you posting you mods etc there. Here is pic of inside of the KAEI TAP-1S. Looks like this pic is with Burson opamp V6 series instead of the stock ones.



Thanks again!
During the current AliExpress Sale, I've ordered a TAP-1S, with the 110V US Power Supply.
They say that it should be here by the 8th of February.
Looking forward to comparing it to my Loxjie P20 (tube hybrid), and my iBasso PB2 (solid state), fully balanced amps.


----------



## Ufanco

DBaldock9 said:


> Thanks again!
> During the current AliExpress Sale, I've ordered a TAP-1S, with the 110V US Power Supply.
> They say that it should be here by the 8th of February.
> Looking forward to comparing it to my Loxjie P20 (tube hybrid), and my iBasso PB2 (solid state), fully balanced amps.



Awesome been debating on buying some different tubes for the Loxjie or buying this instead. Currently running 6N3P-E in it.
I be keeping a eye out for your thoughts on the TAP-1S it looks like a killer little amp. I you haven’t read the thread here on it you should check it out. 
https://www.head-fi.org/threads/kaei-tap-1-portable-hybrid-balance-headphone-amp.958089/


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## Ufanco (Jan 25, 2022)

I’m debating between the KAEI TAP-1 and ORIOLUS BA300S. For $20 more get a much nicer package with the KAEI and power supply. The sale ends today so trying to convince myself to spend the money.
 Source is Shanling M6 PRO 21 using MEST MKII iem.


EDIT I decided on the Oriolus BA300S but definitely be watching @DBaldock9 thoughts on the Kaei tap-1.
 Went with the Oriolus due to more reviews and a few mest mk11 owners recommended it. Someone who owns a KAEI that I talked with says it not the best with low independence iem’s. 

Should have it tomorrow so excited to get a new toy in-house.


----------



## DBaldock9

Received a package tracking email from AliExpress today, saying that the KAEI TAP-1S is in North Texas, headed for Houston - so I should have the amp sometime in the next couple of days.


----------



## Ufanco

DBaldock9 said:


> Received a package tracking email from AliExpress today, saying that the KAEI TAP-1S is in North Texas, headed for Houston - so I should have the amp sometime in the next couple of days.


Awesome looking forward to your thoughts on it. I been using the ORIOLUS BA300S the last 2days and impressed with how well it sounds. Using it with the mest mkii and Shanling M6 pro 21.
No hiss and liking the effects it’s having on sound. Inprovements to the warmth a better bass with little more forwardness on the mids with more smoothness to treble. Even trying it as a pre amp with the Loxjie p20 wasn’t bad.
My concern with the low Independence of the mest and hissing turned out to be non issue. I use a screen orientation app on the M6 and worked out great since now being on side allowing more airflow.


----------



## DBaldock9

Ufanco said:


> Awesome looking forward to your thoughts on it. I been using the ORIOLUS BA300S the last 2days and impressed with how well it sounds. Using it with the mest mkii and Shanling M6 pro 21.
> No hiss and liking the effects it’s having on sound. Inprovements to the warmth a better bass with little more forwardness on the mids with more smoothness to treble. Even trying it as a pre amp with the Loxjie p20 wasn’t bad.
> My concern with the low Independence of the mest and hissing turned out to be non issue. I use a screen orientation app on the M6 and worked out great since now being on side allowing more airflow.



I know that when I was looking at the online info about one of the Oriolus Balanced Amps, one of the details was that it had only a balanced input & output. I wasn't sure if that meant it wouldn't have the correct signal levels if used with a Single-Ended input.


----------



## -rowan-

I thought I’d try rolling op amps on my B4-X, and it seemed like a fairly straightforward job - so I removed stock op amps using tweezers, dropped in new ones (OPA1622) taking care to use the semi circles for orientation. But they didn’t seem to work - so after a few seconds I turned it back off and put back the original op amps, only to discover that there was no longer any sound in the right channel. Tried switching the op amps round, nothing changed and the right channel now seems dead to all intents and purposes. I don’t see any apparent damage; I tried unseating and reseating the op amps, wiggling anything on the circuit board that could be wiggled (but they all seem quite securely soldered), and yes turning it off and on again… still no luck. 

Now I have next to no electronics knowledge, so please be gentle…

Is it possible that I accidentally fried something doing what I described? And is there anything else I can/should try that doesn’t involve replacing various parts? Or is the B4-X a write-off?

I gotta say it was nice while it lasted though… surprisingly quiet, and the balanced output had better separation and layering than I expected. Years ago I bought a dinky little Little Bear tube amp (can’t remember the model offhand) and it was _unlistenable_, which was why it took me ages to come round to trying something else of theirs… but it seems like I just have rotten Little Bear karma.


----------



## rprodrigues (Apr 16, 2022)

@-rowan-

From what you've described, something was fried in the original circuit, unfortunately.

It is possible that the adapter board for the OPA1622 is not compatible  to the NE5532 (pin ordering) or it was faulty.

Could you share the link to the adapter board with OPA1622?

I'm sorry, dude.


----------



## -rowan-

rprodrigues said:


> @-rowan-
> 
> From what you've described, something was fried in the original circuit, unfortunately.
> 
> ...



Thanks @rprodrigues, that sounds likely. Is there any way I can check adapter boards for potential problems in future? 

This was the link: https://m.aliexpress.com/item/4001164295492.html


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## Setmagic

@-rowan- opa1622 dont have short circut protection or reverse placing so if something goes wrong its burn or burn nerby components in extream situations. Most opamps DIP8 have such protection but no this china convertions. Look if its placed in good way.
I think one of connection DIP8 is broken in socket if not probably power delivery module.


----------



## -rowan-

Setmagic said:


> @-rowan- opa1622 dont have short circut protection or reverse placing so if something goes wrong its burn or burn nerby components in extream situations. Most opamps DIP8 have such protection but no this china convertions. Look if its placed in good way.
> I think one of connection DIP8 is broken in socket if not probably power delivery module.



On closer inspection, one of the “103”s is upside down… could that be the culprit? 




Another n00b question - when something gets fried, should I literally expect to see burn marks somewhere? I couldn’t actually see any damage, nor did I even hear anything - it was just my conclusion from all the things I tried.


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## rprodrigues (Apr 16, 2022)

-rowan- said:


> Thanks @rprodrigues, that sounds likely. Is there any way I can check adapter boards for potential problems in future?
> 
> This was the link: https://m.aliexpress.com/item/4001164295492.html




Always ask the seller before ordering.
If still in doubt, once you receive them, ask for someone else to check using a multimeter.

Just as an example, this is the pinout for both NE5532 and OPA1622...


Spoiler







About the flipped 103, no, it is not a problem.



"Another n00b question - when something gets fried, should I literally expect to see burn marks somewhere? I couldn’t actually see any damage, nor did I even hear anything - it was just my conclusion from all the things I tried."

Not always. Sometimes, it just stops working without any trace of "burning".


----------



## Setmagic

@rprodrigues i think right chip is burned, at least looks like 
Adapter looks OK, 1 leg with bad contact after removed socket can burn 1622 as well, and dont run NE ofc


----------



## -rowan- (Apr 16, 2022)

rprodrigues said:


> Just as an example, this is the pinout for both NE5532 and OPA1622...
> 
> 
> Spoiler



I guess that even I can already see how that might be a problem. If I ever try this again, would I be safer with op amps that don’t require adapter boards to be used, so long as I insert them the right way round? Fewer things that could go wrong and all…


----------



## Setmagic (Apr 16, 2022)

-rowan- said:


> I guess that even I can already see how that might be a problem. If I ever try this again, would I be safer with op amps that don’t require adapter boards to be used, so long as I insert them the right way round? Fewer things that could go wrong and all…


This adapter should work everywhere if placed corectly.

2 years ago i was burned mine - exact the same way 
I was made compulsive opamp rolling and figured out this opamp dont have any protection.
But its really best in class, but designed for ultra compact audio and working in pararell, thats why have 2 more pinouts.
Hard to find better one but also need special care.


----------



## alvaroenoht

-rowan- said:


> On closer inspection, one of the “103”s is upside down… could that be the culprit?
> 
> 
> 
> Another n00b question - when something gets fried, should I literally expect to see burn marks somewhere? I couldn’t actually see any damage, nor did I even hear anything - it was just my conclusion from all the things I tried.


I do have the exact same opamps in my b4x and works no problem... does your unit powers on and doesnt make any sound, or just doesnt power on? check the tubes


----------



## -rowan-

Setmagic said:


> 2 years ago i was burned mine - exact the same way
> I was made compulsive opamp rolling and figured out this opamp dont have any protection.
> But its really best in class, but designed for ultra compact audio and working in pararell, thats why have 2 more pinouts.
> Hard to find better one but also need special care.



Oh no, you too! 
Anyway, lesson learnt. I’d read good things  about how this op amp sounds, but clearly need to learn more about them before trying this again. 



alvaroenoht said:


> I do have the exact same opamps in my b4x and works no problem... does your unit powers on and doesnt make any sound, or just doesnt power on? check the tubes



Yep, it powers on and both tubes light up but I only get sound in the left channel now - even the small “pop” when I turn it on.


----------



## alvaroenoht

-rowan- said:


> Oh no, you too!
> Anyway, lesson learnt. I’d read good things  about how this op amp sounds, but clearly need to learn more about them before trying this again.
> 
> 
> ...


the small pop is normal,, have you tried adjusting the bias and gain pots?..just take a pic before moving them to make sure you go back to the original position. if not then you should start reading voltages at different points and make sure everything is ok.. it could be the power supply, left and right is exactly the same circuit so you could use the working one as reference.


----------



## -rowan-

alvaroenoht said:


> the small pop is normal,, have you tried adjusting the bias and gain pots?..just take a pic before moving them to make sure you go back to the original position. if not then you should start reading voltages at different points and make sure everything is ok.. it could be the power supply, left and right is exactly the same circuit so you could use the working one as reference.



Ah yes the small pop is normal, but what I meant is I can’t hear even that in the right channel  No luck on the bias and gain pots either.


----------



## mt877




----------



## Ynot1 (Apr 28, 2022)

I heard a number of times that tubes need high voltage supply to sound good. And then I heard that high voltage is needed for the heater to warm up the tubes properly. And because of this the Chinese made portable tube amps can never be as good as a well designed tube amp with high voltage power supply.  So I was thinking forget the heater and pull out the heat gun. Anybody tried this? Just curious. Avoid heat on capacitors as they can leak prematurely. Maybe capton tape to shield off sensitive areas first.

Edit: At the risk of opening another can of worm, basically physics don't work like arc welding. The heat is primarily at the arc; so you need the arc to melt the metal. In tubes, heat is not the desirable trait, more a consequence.


----------



## mt877 (Apr 28, 2022)

Ynot1 said:


> I heard a number of times that tubes need high voltage supply to sound good. And then I heard that high voltage is needed for the heater to warm up the tubes properly. And because of this the Chinese made portable tube amps can never be as good as a well designed tube amp with high voltage power supply.  So I was thinking forget the heater and pull out the heat gun. Anybody tried this? Just curious. Avoid heat on capacitors as they can leak prematurely. Maybe capton tape to shield off sensitive areas first.


You can't make assumptions... Read this: https://www.junkbox.com/electronics/lowvoltagetubes.shtml

These tubes run at full heater voltage of roughly 6.0 volts. There are 3 grids in these tubes, but they are not used in the normal fashion. G1 is the control grid and G2 and G3 are tied together and used to help accelerate the electrons (space charge effect). The grid configuration I mentioned is for JAN5784WB tubes which are in my B4-X amp. These little amplifiers give a nice tube sound, meaning even harmonics sound.

Because these tubes are running at much lower plate and grid voltages than normal, they will last a long time.

Voltages measured with no input connected. The original schematic was provided in earlier posts for a B4 amp. the B4-X amp schematic is different. This is only a partial schematic of one of the JAN5784WB tubes. For interest, the dual op amp chips in each channel are running with +/- 12 volt rails. Unity gain and connected in parallel. (Meaning the 2 amps in one chip are connected in parallel for each channel.)


----------



## DBaldock9

mt877 said:


> You can't make assumptions... Read this: https://www.junkbox.com/electronics/lowvoltagetubes.shtml
> 
> These tubes run at full heater voltage of roughly 6.3 volts. There are 3 grids in these tubes, but they are not used in the normal fashion. G1 is the control grid and G2 and G3 are tied together and used to help accelerate the electrons (space charge effect). These little amplifiers give a nice tube sound, meaning even harmonics sound.
> 
> Because these tubes are running at much lower plate and grid voltages than normal, they will last a long time.



The Raytheon tubes were designed in the 1950s, for low power military VHF & UHF radios. They may have been in the "receiver / preamp" section, with higher powered tubes in the transmitter.


----------



## Setmagic

Ynot1 said:


> I heard a number of times that tubes need high voltage supply to sound good. And then I heard that high voltage is needed for the heater to warm up the tubes properly. And because of this the Chinese made portable tube amps can never be as good as a well designed tube amp with high voltage power supply.  So I was thinking forget the heater and pull out the heat gun. Anybody tried this? Just curious. Avoid heat on capacitors as they can leak prematurely. Maybe capton tape to shield off sensitive areas first.


This Chiniese cheap amplifiers have fully working tubes as @mt877 said. They working in good voltage specification but lowest voltage values for amplification they are more passing signal insted amplifying, but it's ok.

Yes, they can't compare with well designed full sized tube amplifier becouse they are hybrid and also working in bad environment.
Tubes are sensitive for everything, power supply, voltage regulators, interference from outside and inside device, capacitors values and quality etc, etc...

But they doing the job adding sweet harmonics distortion to sound.


----------



## mt877

DBaldock9 said:


> The Raytheon tubes were designed in the 1950s, for low power military VHF & UHF radios. They may have been in the "receiver / preamp" section, with higher powered tubes in the transmitter.


From the 5784WB data sheet the typical plate voltage is 120vdc which is lower than output tubes with plate voltage often 250vdc and above. So the tubes in these small amps are running in submarine mode... LOL.


----------



## alvaroenoht

guys, regarding tube rolling. I think I have found some substitues for the 5781WB, not that is something wrong with them, but you know how this hobby works.. 
Tubes: 
Sylvania 5638, also running at 6.5v in heater. 
Sylvania 6205

let me know what you all think .


----------



## Setmagic

alvaroenoht said:


> guys, regarding tube rolling. I think I have found some substitues for the 5781WB, not that is something wrong with them, but you know how this hobby works..
> Tubes:
> Sylvania 5638, also running at 6.5v in heater.
> Sylvania 6205
> ...


Better to get them all before tubes prices goes crazy 😃
They should be different but if it's will be visible on that case, can't tell.


----------



## Ynot1 (May 3, 2022)

https://www.aliexpress.com/item/1005001793735776.html?spm=a2g0o.productlist.0.0.29c35561dxPilz&algo_pvid=a5384a11-18af-49a3-96d7-8c30740d2fb9&algo_exp_id=a5384a11-18af-49a3-96d7-8c30740d2fb9-15&pdp_ext_f={"sku_id":"12000017594594105"}&pdp_npi=1@dis|USD||58.62|||||@0bb0624616515991181247905e8a78|12000017594594105|sea

I posted this in the Zishan thread. I could be wrong, but this could be the cheapest.

https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-15848410

Maybe it was called something else before, like GAD HIHF AD III.


----------



## DBaldock9

Ynot1 said:


> https://www.aliexpress.com/item/1005001793735776.html?spm=a2g0o.productlist.0.0.29c35561dxPilz&algo_pvid=a5384a11-18af-49a3-96d7-8c30740d2fb9&algo_exp_id=a5384a11-18af-49a3-96d7-8c30740d2fb9-15&pdp_ext_f={"sku_id":"12000017594594105"}&pdp_npi=1@dis|USD||58.62|||||@0bb0624616515991181247905e8a78|12000017594594105|sea
> 
> I posted this in the Zishan thread. I could be wrong, but this could be the cheapest.
> 
> ...



That's the first Zishan device I've seen that has the Volume potentiometer wired so that turning it clockwise will Increase the Volume.  
All the other Zishans I've seen work backwards from the normal convention - where you have to turn them counter-clockwise to Increase the Volume.


----------



## alvaroenoht (May 6, 2022)

Anyone know if I can replace the red caps with less value than 2.2. I want to replace them with polypropylene caps but at that value they are huge!


----------



## dharmasteve (May 11, 2022)

My first time on this thread....I think.  Well I'm one of the older guys on Head-Fi, grew up with vinyl. Never did have the money for the exotic brands but I remember I really got into the early Dual 505 turntable, Goldring cartridges, and a bit later Musical Fidelity amps in the 80's. I got big time OCD over little T-Amps back in their day. I'm definitely an old analogue-man, lover of world music and almost everything else musically. In July of 2019 I bought the Little Bear 4-X hybrid tube amp and have used it on and off ever since. Lately I found the Little Bear a good match with the Shuoer S12 Planar IEM and got back into using it.
A few weeks ago I got a message from John at Burson Audio asking me if I would like to compare the Burson V5i-D-2 opamp with the stock opamps. I've never been a compulsive Modder, but when necessary I'm up for it. The Little Bear looked simple enough so I found the idea interesting. I had no idea of any difference a new opamp would make to the sound, I'd never changed one before on the Little Bear. So armed with some small Allen Keys, some tweezers and a shaky hand I got going. It turned out so simple to take the board out, take out the stock opamps and put the more substantial Burson's on.
The opamps had arrived a while ago, so I started to deliberately use the Little Bear 4-X most of the time to get back familiarity with the sound. That meant constant charging because the built in battery does not have the longest play time. I chose a few songs to really mainly concentrate on... 'Stimela', live, Hugh Masekela and 'Shovelheads', Shriekback (Yep a bit left-of, but has a lot going on), and the great 'Grandpa's Interview', Neil Young. From Patti Smith, 'We Three', and also some New Model Army tracks.
When comparing and A/B-ing IEMs there is a simplicity to hear the differences. Generally just take one off and put the other on. It takes just a few seconds. Even then there has to be the memory of the previous moments. The moments are close enough to get a fair idea of the differences. When changing opamps there is more time involved in the change so the gap in listening is longer, so possibly more deceptive. It's useful to write keywords down to keep impressions fresh. So what I write here can be taken with a pinch of subjective salt.
Before listening I left the 4-X to warm up for 15mins. First thing I noticed with the Burson, seemingly more RF interference. More sensitive obviously, but that can be good in the long run. Not a problem for me, maybe for some. For me once the music starts this old guy cannot hear the RF so no problem.
Compared to stock the Burson's are less generally fuzzy, and have a much cleaner sound. Leading edges of guitars and drums are more defined and precise, sub-bass is cleaner without losing rumble. A subjective feeling of musicality arises whilst listening with the Burson V5i-D-2's.
Patti Smith's wonderful voice becomes richer, thicker and smoother, yet cleaner in We Three. Same with Hugh Masekela's voice in Stimela and the instruments too. On Grandpa's Interview from the Greendale project, Neil Young has more resonance on the lower register guitar strings, and a kind of vibrato all the way through plus great cymbal crashes later in the track.
There is little doubt the Burson opamps are noticeably different in sound to the OG's. It surprised me that a little opamp can make such a difference. The Burson's are here to stay in my Little Bear and easily give me a large dose of extra enjoyment. I have no idea how much they cost but they double the enjoyment factors.
IEM used, *IMR Splash of Gold*, *Spiral Dot L* tips. Sony Xperia 5ii phone.

Edit....I think a pair costs $59, I've just searched but I've seen various prices. The difference in sound is very clear, even more analogue, *tubey*, so in our never ending search for musical nirvana a good upgrade. After having the Little Bear on for some time the sound has become very analogue indeed.


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## mt877

dharmasteve said:


> My first time on this thread....I think.  Well I'm one of the older guys on Head-Fi, grew up with vinyl. Never did have the money for the exotic brands but I remember I really got into the early Dual 505 turntable, Goldring cartridges, and a bit later Musical Fidelity amps in the 80's. I got big time OCD over little T-Amps back in their day. I'm definitely an old analogue-man, lover of world music and almost everything else musically. In July of 2019 I bought the Little Bear 4-X hybrid tube amp and have used it on and off ever since. Lately I found the Little Bear a good match with the Shuoer S12 Planar IEM and got back into using it.
> A few weeks ago I got a message from John at Burson Audio asking me if I would like to compare the Burson V5i-D-2 opamp with the stock opamps. I've never been a compulsive Modder, but when necessary I'm up for it. The Little Bear looked simple enough so I found the idea interesting. I had no idea of any difference a new opamp would make to the sound, I'd never changed one before on the Little Bear. So armed with some small Allen Keys, some tweezers and a shaky hand I got going. It turned out so simple to take the board out, take out the stock opamps and put the more substantial Burson's on.
> The opamps had arrived a while ago, so I started to deliberately use the Little Bear 4-X most of the time to get back familiarity with the sound. That meant constant charging because the built in battery does not have the longest play time. I chose a few songs to really mainly concentrate on... 'Stimela', live, Hugh Masekela and 'Shovelheads', Shriekback (Yep a bit left-of, but has a lot going on), and the great 'Grandpa's Interview', Neil Young. From Patti Smith, 'We Three', and also some New Model Army tracks.
> When comparing and A/B-ing IEMs there is a simplicity to hear the differences. Generally just take one off and put the other on. It takes just a few seconds. Even then there has to be the memory of the previous moments. The moments are close enough to get a fair idea of the differences. When changing opamps there is more time involved in the change so the gap in listening is longer, so possibly more deceptive. It's useful to write keywords down to keep impressions fresh. So what I write here can be taken with a pinch of subjective salt.
> ...


Nice write up. After I used mine with the TI NE5532 op amps for a while I decided to put in discrete op amps. The ones I installed are OP8802. I had to trim the pins a little for proper height. Afterwards they just fit and are barely touching the plastic window. The OP8802's get pretty hot and the plastic window is extra warm to the touch at the op amp areas, but not enough to cause any harm (yet?). Overall an affordable hybrid tube amp. 

I've been eyeing the KAEI TAP1-S amp which has 4 tubes (2 per channel), longer portable battery life (approx. 10 hours) and dedicated linear power supply.


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## dharmasteve

mt877 said:


> Nice write up. After I used mine with the TI NE5532 op amps for a while I decided to put in discrete op amps. The ones I installed are OP8802. I had to trim the pins a little for proper height. Afterwards they just fit and are barely touching the plastic window. The OP8802's get pretty hot and the plastic window is extra warm to the touch at the op amp areas, but not enough to cause any harm (yet?). Overall an affordable hybrid tube amp.
> 
> I've been eyeing the KAEI TAP1-S amp which has 4 tubes (2 per channel), longer portable battery life (approx. 10 hours) and dedicated linear power supply.


The KAEI TAP1-S looks really good. The road to musical paradise. How lucky we all are in this amazing hobby. As you know I recently got the Shanling M3X. I really like it.....a lot. We are such fortunate people.


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## DBaldock9

mt877 said:


> Nice write up. After I used mine with the TI NE5532 op amps for a while I decided to put in discrete op amps. The ones I installed are OP8802. I had to trim the pins a little for proper height. Afterwards they just fit and are barely touching the plastic window. The OP8802's get pretty hot and the plastic window is extra warm to the touch at the op amp areas, but not enough to cause any harm (yet?). Overall an affordable hybrid tube amp.
> 
> I've been eyeing the KAEI TAP1-S amp which has 4 tubes (2 per channel), longer portable battery life (approx. 10 hours) and dedicated linear power supply.



I've got the KAEI TAP-1S, and have been using it as my primary desktop amp for a month or two.
I have another fully balanced tube hybrid model (Loxjie P20), which is my other desktop amp.
The TAP-1S is quite a bit nicer than my modified B4-X - but the B4-X is about 1/4 the price.


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## mt877 (May 13, 2022)

dharmasteve said:


> The KAEI TAP1-S looks really good. The road to musical paradise. How lucky we all are in this amazing hobby. As you know I recently got the Shanling M3X. I really like it.....a lot. We are such fortunate people.


Yes, very fortunate. I like the M3X as well. It pairs up perfectly with the Little Bear B4-X. They are almost the same physical size, so banding them together is a good match. They both have audio connections on the top, so connecting the M3X 3.5SE output to the B4-X 3.5SE input is easy. I band them together with both devices facing outwards, so just flip 180 either way and you are looking at the face of the M3X or the B4-X. Also if you want to switch the M3X 3.5 from headphone out to line level out you can drive the B4-X at line level. I don't have any high impedance headphones, IEM's or flathead earbuds, so switching to line level isn't necessary. I did try it, but then I can only turn the volume knob on the B4-X a smidge off of minimum before I hit max comfortable listening volume on lower impedance headphones, IEM's or buds.



DBaldock9 said:


> I've got the KAEI TAP-1S, and have been using it as my primary desktop amp for a month or two.
> I have another fully balanced tube hybrid model (Loxjie P20), which is my other desktop amp.
> The TAP-1S is quite a bit nicer than my modified B4-X - but the B4-X is about 1/4 the price.


For home setup I can get tubey goodness listening through an iFi Retro Stereo 50. I also have a Sherwood S-5000 which doesn't have a headphone out, but I found plans to build a headphone out for the S-5000. Will definitely be one of my future DIY projects.


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## Ufanco

DBaldock9 said:


> I've got the KAEI TAP-1S, and have been using it as my primary desktop amp for a month or two.
> I have another fully balanced tube hybrid model (Loxjie P20), which is my other desktop amp.
> The TAP-1S is quite a bit nicer than my modified B4-X - but the B4-X is about 1/4 the price.



Glad to hear the Tap-1S is working out for you. If the ORIOLUS BA300S ever died on me, I more than likely go with KAEI TAP-1S instead since the ORIOLUS BA300S get used many as a pre amp now. 
I picked up a Xduoo TA20 so been having a blast with it. My Loxjie P20 (for sale) is a good little amp but since I got a great deal on the Xduoo it’s gather duct.


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## povidlo

excellent synergy with nos dac and planar cans.


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## povidlo

Finished building Nu:Tekt HA-S.

Drives my 150ohm/89db IEM very well.

Seems like high quality parts are used, what do you guys think?


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## ChrisOc

For those who have the Littlebear B4X, Burson V5i D modification and review.






https://www.head-fi.org/showcase/littlebear-b4x-portable-tube-dac-amp.25867/


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## ChrisOc

povidlo said:


> Finished building Nu:Tekt HA-S.
> 
> Drives my 150ohm/89db IEM very well.
> 
> Seems like high quality parts are used, what do you guys think?


How much technical knowledge does the build need?

By the way, it looks cool!


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## povidlo

ChrisOc said:


> How much technical knowledge does the build need?
> 
> By the way, it looks cool!


Very little! Easier than putting together a piece of Ikea furniture. There are step-by-step instructions and a YouTube video available as well. Took me 45 minutes but a handy person could get it done in 15.


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## Punslayer

I've been using the HA-S for a few months and like it quite a lot.  It does have one big limitation; 10 ohm output impedance, but it has a black background and sounds very good with everything I've tried so far.

No soldering is required, so it's very easy to assemble.  It is a little expensive compared to the amps discussed in this thread, but worth it to me.


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## povidlo (May 28, 2022)

Punslayer said:


> I've been using the HA-S for a few months and like it quite a lot.  It does have one big limitation; 10 ohm output impedance, but it has a black background and sounds very good with everything I've tried so far.
> 
> No soldering is required, so it's very easy to assemble.  It is a little expensive compared to the amps discussed in this thread, but worth it to me.


10 ohm output impedance works better for 150 ohm+ transducers than <1 ohm output.

Also planar magnetic driver frequency response is little impacted by output impedance, not as much as dynamic/ba.

Looks like you're using 1.2v rechargeable AA while manual says to use 1.5v AA which is usually the non-rechargeable kind. Have you noticed any difference vs using 1.5v AA?


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## Punslayer

I only used regular alkaline AAs briefly, but no I didn't notice any difference when switching to rechargeables.

In my case, the majority of my headphones are low impedance, including some that are very low.  The IEX1 are only rated 5 ohms and I have read that they dip below that significantly.  They still sound good on the HA-S.  I'm sure I'll run into some that are negatively affected; I suspect that the Final F7200 will not be good, but haven't tried them yet.


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## bcschmerker4

ChrisOc said:


> For those who have the Littlebear B4X, Burson V5i D modification and review.
> 
> 
> 
> ...


Which type pentodes does the Littlebear B4X use?  The pentodes are miniature-7-pin.


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## DBaldock9

bcschmerker4 said:


> Which type pentodes does the Littlebear B4X use?  The pentodes are miniature-7-pin.



Back in January of 2021, a couple of us in this thread [ https://www.head-fi.org/threads/portable-tube-amp-from-china.626237/post-16095330 ] determined that two different versions of the B4-X have been built - the original one uses the Raytheon JAN5899, and the newer one uses the Raytheon JAN5784WB. These two tubes don't have the same pin-outs (5899 has circular pin grid, 5784 has straight pin grid) or specs, so the board circuits are different, and the tubes aren't interchangeable.


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## paulic5003

mt877 said:


>


What op-amps are those?


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## DBaldock9

paulic5003 said:


> What op-amps are those?



They look like Sparkos SS3602.


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## paulic5003

DBaldock9 said:


> They look like Sparkos SS3602.


Do they fit in without any modifications to the B4-X? have you compared them with the Burson v5i?


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## mt877

paulic5003 said:


> What op-amps are those?
> 
> 
> DBaldock9 said:
> ...


They're Lusya OP8802. They were a bit too tall so I had to cut the pins down to get them to fit.


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## mt877

povidlo said:


> excellent synergy with nos dac and planar cans.


Just wanted to say nice job on modifying the plastic window to fit the Burson V6.


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## povidlo

mt877 said:


> Just wanted to say nice job on modifying the plastic window to fit the Burson V6.


thanks. i discarded the plastic window and used a hand file to remove the extra metal that protrudes to keep the window in place. without filing down that extra metal, V6 doesn't fit straight up. then, i applied clear packaging tape instead of the plastic window to protect the board against dust and to add some stability to the pair of V6 as well. basic but works .


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## paulic5003

mt877 said:


> They're Lusya OP8802. They were a bit too tall so I had to cut the pins down to get them to fit.


Could've find any reviews of the op8802. But there are several glowing reviews of the Sparkos ss3602. Does anyone know if the Sparkos will fit inside the B4-X?


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## DBaldock9 (Jun 7, 2022)

paulic5003 said:


> Do they fit in without any modifications to the B4-X? have you compared them with the Burson v5i?



NOTE: I have the first generation of the B4-X, which does not have the relay near the "front" of the circuit board. 
. 
Since I built new tube carrier boards (for my B4-X), that move the tubes closer to the edges of the case - there's plenty of space for wider devices, like the Sparkos, or Lusya.
.
Otherwise, one of Sparkos was touching a tube, while the other just barely cleared.


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## paulic5003

Thanks. I saw your previous post with a picture of the tube carrier. Without your mod are the Sparkos usable at all? Or is your mod necessary?


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## DBaldock9

paulic5003 said:


> Thanks. I saw your previous post with a picture of the tube carrier. Without your mod are the Sparkos usable at all? Or is your mod necessary?



Yes - they fit, but one side was tight. 
. 
I do not know whether the current B4-X has the same amount of space between the tubes and the sockets.


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## mt877 (Jun 7, 2022)

paulic5003 said:


> Could've find any reviews of the op8802. But there are several glowing reviews of the Sparkos ss3602. Does anyone know if the Sparkos will fit inside the B4-X?





SS3602 dimensions




OP8802 dimensions

SS3602 slightly smaller width 13.75mm vs OP8802 width 14.5mm.
SS3602 slightly lower height 13.87mm vs OP8802 height 16mm.

For the OP8802, the pins were long and would not insert flush, so I cut approx. 2mm off each pin. Height-wise it is a tight fit and the top surface of the amps touch the plastic window and do feel hot (not blistering hot) against the plastic window. I tried to remove the factory socket, but it was very tight and would not budge. I didn't want to destroy the op amps trying to remove the sockets, so just cut the pins a little shorter. I think the fit of the SS3602 will be about the same as the OP8802.

The electronic spec for both SS3602 and OP8802 are very similar.

I have the newer version of the B4-X. The OP8802 is slightly wider, but not touching the tubes.

Edit:



Right channel clearance




Left channel clearance




Top clearance

For top clearance, I put a ruler across the top and bottom panels. It shows some clearance, but when you reattach the top clamshell cover (with window), the window area actually touches the op amp components, at least that is what happen to mine. Before I cut the pins down I could not put the top clamshell cover on. The window is held in place with double stick tape and the op amps popped the bottom edge of the window up, separating the edge away from the double stick tape. If you run into that problem you may need to use thin double stick foam like what you get with 3M Command hooks to space the window out a little to get some clearance.

Hope that helps.


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## paulic5003

DBaldock9 said:


> Yes - they fit, but one side was tight.
> .
> I do not know whether the current B4-X has the same amount of space between the tubes and the sockets.


Thanks. mt877 has the new B4-X which is the one I have. Looks like there is just enough room for the Sparkos.
​


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## paulic5003

mt877 said:


> SS3602 dimensions
> 
> 
> OP8802 dimensions
> ...


Thank you for the detailed specs and the photos. Very helpful indeed.  I'll give the SS3602 a try as they are slightly smaller.


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## mt877

As much as I like the sound from the OP8802 discrete op amps I had to pull them and put the Ti NE5532P op amps back in (for now). The OP8802 started to have random oscillations which just ruin the listening experience. I would probably have to add 100nF decoupling caps across +Vcc to Gnd and -Vcc to Gnd as close to the chips as possible to fix the oscillations. I'm thinking of going with LME49720 op amps which are high quality audio amps. Of course they aren't as 'sexy' looking as discrete op amps, but I think the sound will be very good.


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## borkenarrou

Are there good quality shielded aux cable for the b4-x, preferably a bit longer, the supplied cable I feel is bit noisy as it picks interference from things like mob phones etc.


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## fabien32

borkenarrou said:


> Are there good quality shielded aux cable for the b4-x, preferably a bit longer, the supplied cable I feel is bit noisy as it picks interference from things like mob phones etc.


https://www.amazon.com/Boaacoustic-...hq+ofc+shielded+3.5+mm+cable+,aps,264&sr=8-15

https://www.amazon.com/DuKabel-Audi...=hq+ofc+shielded+3.5+mm+cable+,aps,264&sr=8-2


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## triggrhaapi

borkenarrou said:


> Are there good quality shielded aux cable for the b4-x, preferably a bit longer, the supplied cable I feel is bit noisy as it picks interference from things like mob phones etc.


The problem most likely isn't the cable, it's the tubes. Any longer cable will be useful for keeping your phone away from the amp, because it's tube microphonics that are the issue.


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## mt877

triggrhaapi said:


> The problem most likely isn't the cable, it's the tubes. Any longer cable will be useful for keeping your phone away from the amp, because it's tube microphonics that are the issue.


B4-X tubes are picking up wifi interference. In some of the earliest posts some guys were lining the case with copper foil to block wifi interference. When I stack the B4-X with Shanling M3X and turn on the wifi I can hear the noise caused by the tubes. Noise goes away after turning off the wifi. I’m gonna have to reread those posts for the copper foil lining mod myself.


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## triggrhaapi

mt877 said:


> B4-X tubes are picking up wifi interference. In some of the earliest posts some guys were lining the case with copper foil to block wifi interference. When I stack the B4-X with Shanling M3X and turn on the wifi I can hear the noise caused by the tubes. Noise goes away after turning off the wifi. I’m gonna have to reread those posts for the copper foil lining mod myself.


Honestly, it doesn't take much physical distance to stop the interference. I got the same thing from the radio on my cell phone, and all it took was putting it in a pocket on the other side of my jacket from my phone to stop the noise. Maybe a foot and a half / half a meter or so is plenty.


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## mt877

triggrhaapi said:


> Honestly, it doesn't take much physical distance to stop the interference. I got the same thing from the radio on my cell phone, and all it took was putting it in a pocket on the other side of my jacket from my phone to stop the noise. Maybe a foot and a half / half a meter or so is plenty.


Cool, glad that works for you. I want to stack my DAP and B4-X together so will do a different solution.


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## Mouseman

mt877 said:


> Cool, glad that works for you. I want to stack my DAP and B4-X together so will do a different solution.


Just be careful with that foil - I cut one of my fingers right away working with it, and did the rest of the work with gloves on. That stuff is really sharp!


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## triggrhaapi (Oct 19, 2022)

mt877 said:


> Cool, glad that works for you. I want to stack my DAP and B4-X together so will do a different solution.


I mean live your life, but even the best faraday cage will not block 100% of the noise if you're stacking this with the source of the noise. Shielding is about attenuation, not elimination. The tubes are _sensitive, _so even if you stacked them with a gap between you're going to get significantly less noise than if you added extra shielding (the aluminum case is already shielding in and of itself) and still put this amp directly on top of the source of the noise. That's just how electromagnetic radiation works.

Also, and I have to point this out, adding shielding but not addressing the fact that there is a giant window over the super sensitive tubes is well, an oversight to say the very least.


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## Mouseman

I actually put the foil over the window, because that is a stupid design choice. I ended up taking it off because I missed the glow. 

If you're going to open it up, you might want to put some o-rings over/on the tubes. That helps the microphonics a decent amount.


----------

