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Portable tube amp from china?

Discussion in 'Portable Headphone Amps' started by voodoo do-er, Sep 6, 2012.
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  1. reddragon

    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 :D
  2. 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.
  3. Spriggs
    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.
  4. reddragon
    how much did it take you to build the amp? and i have no experience in diy.
  5. 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.
  6. reddragon
    ok thanks, i have no experience in diy and i dont think i will be good at that but i will look around
  7. Nectar
    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.
  8. mrarroyo Contributor
    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.
  9. Spriggs
    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.
  10. penmarker
    [​IMG] [​IMG]
    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.
  11. Spriggs
    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$
  12. 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.
  13. voodoo do-er
    OP check.
    yep, I'm the OP here. :p
  14. 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.
    vinokurov likes this.
  15. 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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