A Perfect Match ~ Venerable TU-8200R Powers The NanoOnkens Sweetly 19Dec24

I sought the right amp to power the somewhat sensitive (86dB @ 1watt @1meter) NanoOnkens. I've "always" been curious about the Japanese Elekit TU-8200R amp DIY kit. First, the sound at 8 watts is supposedly awesome (though I'd never heard one), but additionally it receives wide accolades from audiophiles on it's clever auto-biasing circuit ~ aiding those wanting to mod & tube roll the amp. So, I built one! It's actually a Christmas gift from Kala, but yeah, I specified, found, and acquired it. There are more modern variants from renowned Mr Fujita but I found a TU-8200R that could accommodate an inboard DAC (also a DIY build) as well, and it was a lot less expensive than his newer stuff. Holy mackerel this is a perfect combination ~ I can fill a big room no problem and the sound is GR8 driving the NanoOnkens full range in free space alone, or when supported by the NanoSub. Woohoo.

Building The 8200R... I mentioned it's DIY. I bought the kit with English instructions, but for $150 less you can still get one direct from Japan without. The build was straightforward and took me 12 hrs or so, on and off. This thing is heavy, solid, and of great build quality; I found only one error in the instructions, and even that is debatable. Howdy there are many screws, but everything registers correctly. Just a few images from the build process...

Firing Up The 8200R With NanoOnkens... I was fortunate to have my build run correctly on initial fire-up! I didn't yet make any capacitor or transformer upgrades as profiled by some DIY audiophiles. I first ran the stock JJ 6L6GC power tubes with the stock JJ ECC82 pre-amp tubes, as these are already pretty nice. Beautiful. But I had a hankering to use that auto-biasing circuit, and the 8200R can support a variety of power tubes, including 6L6GCs, 6505s, KT88s & the series, and EL34 & like... quite a range. And, using jumpers, one can set the amp to run power as pentode, triode or ultra-linear (efficient like pentode but accurate like triode). All my initial measurements are made in triode strapping ~ I could easily get 95dB from the NanoOnkens and I preferred it best, but I may go back and measure other modes. Lastly before impressions and measurements, I stayed with the stock ECC82s throughout, but again, I may well roll through some new pre-amps later.

Listening To And Measuring The Kit... I first listened to 10,000 Maniacs' "From My Tribe" spit from my Onkyo DP1 through the new TU-8200R & the NanoOnkens ~ stellar; then I heard Al Stewart's "Modern Times" ~ heard every instrument. Finally AJ Lee & Blue Summit gave me "City of Glass" and I played Molly Tuttle's & Golden Highway's "City of Gold," I'm a super-fan of these and they both sounded great on the system. The NanoOnkens are amazing, even more so now driven from a high quality tube amp. I took measurements of course and the flatness 80Hz-22KHz is evident. The NanoSub hookup has to be at powered level unfortunately as the 8200R does not have a sub-out at line level. That's not a big deal as the down-converter in my plate amp does not appreciably alter the impedance back to the amp or speakers. I took NanoSub measurements at several crossovers and chose the 110Hz setting and only 35% gain as the best mating to the speakers driven by this amp and wiring the sub as variable. I then also measured the whole integrated NanoKit. My sub placement for measurement is not ideal and I will of course remeasure when I find this kit a home.

Tube Rolling In The TU-8200R... I have two non-stock sets of power tubes for the 8200R of which to listen and measure: a matched pair of Tang-Band 6550s and a matched set of Psvane KT88s. These, like the JJs, are modern manufactured tubes, not NOS tubes. As mentioned, accomodating the new power tubes is just a matter of turning the amp off, letting the current tubes cool sufficiently to pull them, and reinserting the news ones. Surprising to me was that all 3 sets of power tubes measured almost equivalently. The NanoOnkens and the room environment dominate the situation. There is some faster rolloff measured in the highs with the KT88s though. More was apparent in the listening realm. I heard the difference with the KT88s before measuring it; the Psvanes just didn't deliver the vibrancy I'd seek in the high end. These tubes were stock removed from my Willsenton amp that I use to drive the center channel in the NestMT; they were replaced by Mullard EL34s ~ and I will try a pair of those in the 8200R at some point. Too bad I don't like the Psvanes more; they are the best color match to the copper-coned NanoOnkens ~ ok, not too important. If hard pressed to decide between the other two, I'd have to say that the Tang-Band 6550s seem a bit more dynamic than the JJ 6L6GCs, so they'll stay in the sockets for now. I am really pleased beyond expectations with the range, dynamics, and overall sound of the NanoKit driven by the TU-8200R.

Building PS-3249R Onboard DAC... I built the optional "integrated" DAC and installed it in the 8200R. Finishing and installing the DAC was straight-forward. This DAC is not the best I have or have heard but at just $50 for a 16bit/48KHz delta-sigma DAC that travels with the new 8200R, it's awesome. There were plenty of options in the build that I did not strap for, like SPDIF out, external clocking, external power, etc. Those seem primarily for when you want to build a separate box for it.

So, despite its being inside the cabinet, it is not connected to power in there or even the amp board. Power is supplied from the digital source (most often a computer) and the odder part is that its "analog out," via 3 pole mini-DIN is fed to the amp via the source 2 mini-DIN "in" on the amp! Fortunately I had a very short male-male mini-DIN cable perfect for the task. The line out level from the DAC is strong so the amp plays pretty loud without further mods. I streamed some YouTube (Sabrina Carpenter in the pic, but I did rock, bluegrass, and more as well) to test and the DAC is fine... neh good.

I will A-B the onboard DAC against the excellent miniDSP 2x4HD once I retrieve it from Summit. It is 32bit/192KHz and would even allow me to do some DSP on the NanoKit output ~ though that is not very necessary, and I could send the sub just what is necessary at line level. I will also be rolling the pre-amp tubes (which may impact power tube choice as well). So fun, so excellent.