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... the EleNanoKit is born.
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.
Power Tube Rolling In The TU-8200R... I have three non-stock sets of power tubes for the 8200R of which to listen and measure: a matched pair of Tang-Band 6550s, a set of Psvane KT88s, and a pair of Mullard EL34s. These, like the JJs, are modern manufactured tubes, not NOS tubes. As mentioned, accommodating 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 4 sets of power tubes measured very similarly. 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 tried those too here. Too bad I don't like the Psvanes more; they are the best color match to the copper-coned NanoOnkens ~ ok, not too important. The EL34s are very nice and measure fine too... they are smoother in the lows and low-mids but also roll off a bit in the highs. If hard pressed to decide between these, I'd have to say that the Tang-Band 6550 and Mullard EL34s are more dynamic than the JJ 6L6GCs. After some more tunes (Sarah Jarosz "Polaroid Lovers") I feel the 6550s are just nicer than the EL34s in the mid-highs, so they'll stay in the sockets for now. I'll return the Mullards to their rightful spot in the NestMT center channel. Measurement #1 below is without the sub and #2 is with sub support. I am really pleased beyond expectations with the range, dynamics, and overall sound of the NanoKit driven by the TU-8200R. Plus, it's fun to roll.
Building PS-3249R Inboard 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 for signal path. Power is supplied from the digital source via USB (most often some kind of computer) and the odder part is that its "analog out," via 3 pole mini-DIN 3.5mm is fed to the amp via the input 2 mini-DIN "in" on the amp! Fortunately I had a very short male-male 3 pole 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.
Comparing DACs... I will A-B the onboard DAC against the excellent miniDSP 2x4HD. The latter is a 32bit/192KHz DAC and would even allow me to do some DSP on the NanoKit output ~ though that is not very necessary from what I've heard and measured. I will also send the subwoofer a signal @ line level with even tighter rolloff when using the miniDSP. I do not expect measurable differences but I will listen carefully too. Weird... the miniDSP was noticeably more distorted than the Elekit one; THD was typically 2X-3X the Elekit at points across the audible spectrum. So, while it was nicer at times (5KHz-9KHz for instance), and closer to "true," I'm not gonna use the miniDSP with the Elekit. That's OK for another reason: it was harder to keep stable with the Elekit, which seemed to drop to 10% volume on occasion when driven by the miniDSP. Here are the SPL shots of each DAC and the sub. Also, spectrograms alluding to the additional distortion in the miniDSP config. All DAC compares were done with the 6505s back in the amp.
I also grabbed some women's cuff bracelets to act as shields for the power tubes, which get dang hot. Ultra-DIY baby (though I stole the basic idea from an amp I saw somewhere). And, I added grills to the front of the NanoOnkens to protect the drivers; I've now colored the magnets securing them black. And, I got real stands for the NanoOnkens... they are an odd but all steel design I liked for the tiny upper platform. I padded the plate with foam feet and added an anchor to the back of the NanoOnkens. Very solid stuff. I also cleaned up the cable routing installation with some nylon mesh sleeves.
Update 02Jan25 ~ Rolling The Pre-Amp Tubes... I bought several additional keen pairs of preamp/driver tubes for the 8200R. I chose different tube styles from around the world; all are well thought of but not whacky $1K/pr choices (to compare, the modern, stock, JJ ECC82s are $40/pr) ~ I'll listen, measure, and document using these with my favored Tung Sol 6505 power amp tubes in triode mode. I don't have the gear to measure the amp itself or the changes I have made with tube rolling ~ just my ears and closed loop measuring the sound through the NanoOnkens.
- Tungsram ECC82 ~ matched pair NOS NIB MINT. Hungary NOS 1980 $110/pr
- Raytheon JAN 5814A ~ matched pair of premium industrial grade 12AU7s with triple mica support and rare windmill getters. US NOS 1960 $100/pr
- Valvo ECC82 ~ matched pair with rare tilted getters. Germany NOS 1960 $150/pr
I have the modern JJ ECC82s from stock with the amp and the Tungsram 1980 NOS ECC82s were the first new tubes to arrive. I've been listening to the JJs for a while now but when I flipped to the Tungsrams things became clearer and more defined to my ear. Not more dynamic per se, just cleaner all up and down the spectrum... voices and instruments popped out better. I listened to Jade Bird's "Different Kinds of Light" and caught it all with the Tungsrams, but lost some highs with JJs. The Tungsrams were not bright in any way really, just nicer and more revealing. I thought measuring might show me why but the SPL sweep 23Hz-23KHz showed little difference; the JJs were a tiny bit hotter.
Then I compared the distortion curves which might better explain what I heard. The Tungsrams (1st) show substantially lower THD and variance across the spectrum than the JJs.
Potential distortion is also shown in the spectrum rendering of the measurements; they are equivalent.
I'm sticking with the Tungsrams for now but I am eager to hear the other cool drivers that are still in the mail. Yoho came over with some Modus and approved the narrower config with a sound-absorbing blanket for nearby wall reflections... once I plugged the amp back in the outlet. :)
Update 17Jan25 ~ Rolling The PreAmp Of The TU-8200R... Some keen new vacuum tubes arrived and I sat down today for a full investigation of the new (& old) driver tubes for this flexible amp. All preamp listening will be done on the NanoOnkens @ Blodgett powered by Tung Sol 6505s in the 8200R, with the NanoSub active. I'm aided tonight by the fine Abomination DDH offer "Into The Fog." Don't take my assertions forward as unclear... I can see through the fog.
For recap, here are the drivers I'll be comparing:
- JJ ECC82 ~ stock, modern manufactured. Slovak Republic. $40/pr
- Tungsram ECC82 ~ matched pair NOS NIB MINT. Hungary NOS 1980 $110/pr
- Raytheon JAN 5814A ~ matched pair of premium industrial grade 12AU7s
with triple mica support and rare windmill getters. US NOS 1960 $100/pr
- Valvo ECC82 ~ matched pair with rare tilted getters. Germany NOS 1960 $150/pr
Right off listening, the JJs still lack the luster and definition of the Tungsram (noted far above), and now too vs the Valvo pairs. Sweet female vocals and keen guitars as with Molly Tuttle, AJ Lee, Twisted Pine, Phoebe Bridgers, and others fall short. And the mid-bass wants on the new JJs as well, but the Tungsram and Valvo preamps let the 6505s hear it all and give me that thing. Rolling on... the solid (triple mica) Raytheons sucked - upper mid-range shredded badly to my ear. I much preferred the Tungsrams or Valvos on the listening sessions ~ little distinction between these two thus far. Noteworthy that the pair of Valvos were produced in the same week, in the same German factory, by Valvo, but were branded differently as Siemens and Haltron, but are well-matched... I don't care about branding given all else. I'm tech not freak afterall. 1st chair is down to the Tungsrams or Valvos. Though, the rejected RayTs glowed nice...
I caught too much data but I'm showing just the relevant smidge. The Valvo pair should "win" if I correct the mid-bass "dip" of on either Tungsram or Valvo... and even otherwise "on paper."
