Posted by Sebrof (A) on April 20, 2010 at 16:13:55

Sorry if this is long winded, but I thought I'd post my impressions of the TU-879.
Thanks to Victor for bringing this product to the N.A. market, and also for translating the manual. It was flawless.

I got the TU-879 a couple of weeks ago and put it together – Took about 8 solid hours. Build went without a hitch, but when I turned it on nothing happened. I opened it and found a blown fuse (300 mA) – Replaced and it has worked fine ever since.

System: Arcam Alpha 8SE CD Player, Elekit TU-879, Klipsch Klipschorns. Dedicated 13’ x 12’ room.
Tubes: Sovtek 5751 driver, Stock Electro Harmonics 6L6EH, Svetlana EL34, Russian 6n3c-e 1980s NOS (courtesy of Mikhail Gorbachev) from Jim McShane ($31 delivered, awesome deal!).

2 other amps: A Decware ZKit1 and a DIY 807-based single ended with the 807s wired in triode.
Do not underestimate either of these amps. The Decware @ $350 or so (with tubes) puts out about 2 watts, but the bass and fullness of this little amp is very good. It does not have as much ‘magic’ in the midrange as the 807.
The 807 puts out about 6 watts and has quality parts including James output transformers and an Alps pot. It has SET midrange magic but perhaps ever so light in the bass. I’ve had this at an audio meet and hooked it up to a very nice pair of custom horns. The amp was very impressive and people asked for the schematic, asked me about the build, etc.

I work from home so the amp has been on almost all day every day since I built it, and I have listened to it a lot, especially in the evenings. So we can say it’s been on for about 150 hours or so, part of the time with different tubes.
First off, this amp is DEAD QUIET. Not a hum, buzz, whistle, or ring at all. Turn on the power switch and absolutely nothing changes except a couple of LEDs light and tubes start to heat up. Remember, the KHorns are 104db, and no other amp has been dead quiet except for a Primare SS integrated I had when I first got the KHorns. I did not believe this was possible with KHorns and tubes.

Going in to this amp build, I thought that if I could get bass as good as the Decware and mids as good as the 807 I would be happy. So far, this little amp has delivered in both regards. What I did not consider was that the 807 also presents a bit of high frequency harshness, maybe more to do with speakers and room, but it’s there. The -879 has very little, if any, high frequency harshness.

I would describe the sound as warm, perhaps even lush especially with the 6L6s installed. Definitely not bright or forward. With Pentodes, I may be giving up a little of the SET magic, but the overall presentation is quite nice.
• 879 vs. Decware – The bass of the 879 is every bit as full as the Decware, but the 879’s bass is tighter. The 879’s mids are better than the Decware. The 879 also plays complex passages louder with much more clarity, and gives the listener the sense that it has plenty of balls (hard to say that about an 8-watt amp without a chuckle). A pair of Decwares bridged might be similar to the 879 in all around presentation except for midrange, because the *relatively* loose bass and compression when played loud would probably both be addressed with more Decware power.
• 879 vs. 807 – The most obvious difference between these 2 amps is the bass. As soon as a song starts to play you notice it, no question. The mids are similar, maybe a slight edge to the 807 but it’s hard to say because with lower volume of bass the mids on the 807 jump out a bit more. The other major difference is in the high frequency glare that the 807 has a tendency to present. With the 879 this glare is gone, if not totally then practically. With the 807 I was always looking for ways to reduce the glare by tweaking the KHorns or with room treatments. We’ll see if I go there again, but I believe my days of tweaking to “Tame Those Horns” are over. I think the 879 tamed them.
• 6L6 vs. 6n3c-e vs. EL34 – Still breaking these in (EL34 are used, and the 6n3c-e’s and 6L6s have probably 50 hours on them), but here are my impressions so far: the stock EH 6L6s have more bass, maybe too much, and can get a little muddy at times. EL34 has a muddy midrange at times. 6n3c-e has a good balance of bass and mids, perhaps a little bright when played very loud, but I don’t play that loud anyway. All tubes sound good, my least favorite is the EL34. At this point I probably prefer the 6n3c-e’s because they seem to be more balanced. But the EH 6L6s are in now way harsh, and they have that gorgeous blue glow…pretty!

Having said all of that, my system with the the 879 is a joy to listen to, whether played very low (when my wife and I sit and have Sunday morning coffee), moderate (most of the time), or very loud (testing to see what the amp can do). It belies it's modest price tag in build quality and in sound. I don’t see taking it out of the system any time soon except to play and compare. With several driver tube choices and many power tube choices, it should keep me busy for a long long time.
Now it’s off to see if I can get a deal on some KT88s, or 6550s, or KT66s, KT77s, 6L6s,…