Gramophone Dreams #74: Elekit TU-8900 kit amplifier

It was a cold March-in-Brooklyn morning. Clouds had been shedding wintery mix since daybreak. By 9am, birds were flash-mobbing my window, demanding suet. But I was frozen—unable to pull my mind loose from the grave flowings of American composer Ned Rorem's Book of Hours, as performed by Les Connivences Sonores on the album Musikalische Perlen (24/48 FLAC, Ars Produktion/Qobuz). The sounds in my room were sensuous and mesmerizing, and I needed to float in their mysterious energy as long as I could.

I was listening through the most compelling sound system I had assembled since I started writing for Stereophile. The dCS Bartók DAC/streamer was funneling the harmonic purity and hypnomagik of Odile Renault on flute and Elodie Reibaud on harp into HoloAudio's appropriately named Serene preamp, which was feeding Elekit's TU-8900 300B/2A3 kit amplifier, which was sending a few of its triode-tube watts to the TAD's $32,500/pair Compact Evolution One monitors, more compactly known as the TAD CE1TX. I reviewed these three-way standmount speakers last month, finding them to be the most exciting, accurate-sounding, well-engineered speakers I've encountered.

What was unique about this system was not how it sounded but how easily it enabled diverse forms of music to summon reverie and affect my state of mind—how it made rhythms linger in my head after the music stopped.

My review was finished, and I knew the TADs were leaving tomorrow, so I figured that day would be best spent bathing in the completely crazy fantasticness of an 8W, relatively inexpensive, made-in-Japan kit amp (!) driving a 4 ohm, 85dB-sensitive, also-made-in-Japan box speaker of the highest pedigree.

Well-recorded compositions for flute and harp leave no place for dry-sounding feedback amps or dull-sounding box speakers to hide. Both instruments' harmonics must be fully exposed. For these high-energy instruments to have a touchable vibratory presence, a system's upper octaves need to be information-rich, pure, extended, and harmonically complete. Somehow, on that day, that Elekit-TAD combo was doing what felt like a perfect job of being pure and harmonically complete.

The above-described pleasures were not, I believe, just a lucky consequence of a chance pairing of Elekit's new (in 2022) TU-8900 300B/2A3 amplifier with an expensive three-way box speaker. There was more going on. What actually happened, I believe, was that the CE1TX's easy-to-drive, highly descriptive nature responded very well to the flood of small data issued by an amplifier pumped up on three sources of information-preserving steroids: Lundahl's made-in-Sweden LL2785C AM amorphous-core output transformers and Audio Note UK's tantalum resistors and silver-foil coupling capacitors.

The North American version of the TU-8900 kit has been heavily parts-curated by the frugal, creative mind of Elekit's Vancouver-based distributor, Victor Kung of VK Music (footnote 2). The result is a kit amp with the same quality of parts as many of the world's finest and most expensive triode amplifiers. I have a globally respected Euro-friend who builds custom 300B amplifiers on commission, cost no object, deep into five figures, and he's using the same level of Lundahl output transformers as the $1945 TU-8900 (below). The $15,000 Shindo Laboratories Cortese 300B amplifier uses them, too.

My TU-8900 kit came preassembled (a $375 option) with a clear acrylic top plate that allows me to admire the conspicuous legion of Kemet solid polymer aluminum capacitors (footnote 2) and the two large, symmetrically placed Audio Note 0.1µF silver-foil coupling capacitors. These are Audio Note UK's highest-quality capacitors, a step up from the excellent copper-foil caps used in the $19,300 Audio Note Meishu reviewed by Ken Micallef in January's Stereophile. VK Music sells Audio Note's silver-foil coupling caps for $355 each. The Audio Note tantalum-resistor option replaces all 46 resistors in the signal path, two Amtrans AMRG resistors, and four Takman carbon resistors for $265. My TU-8900 came with the full Audio Note Silver upgrade, which costs $960 and includes all of that plus two acrylic brackets for securing the large silver capacitors.

The clear top plate, which is included in the cost of assembly (and a $35 option with the kit), turns an ordinary, classically styled tube amplifier into a dramatically visual, sci-fi–looking bit of audio architecture, one that manages to look futuristic and understated at the same time.

In addition to the Chernobyl-red LED light flooding out from the power supply modules stationed below the transformers and the orange glow of the Venus tubes protruding from the clear deck, bright twin LEDs flank and backlight the volume control at center front. These relatively large, symmetrically placed bulbs glow green on startup as sensors measure heater current to determine whether the power tubes installed are 2A3s, in which case the LEDs stay bright green, or 300Bs, in which case they turn blue.

With the abovementioned options, my TU-8900 costs $3280 without tubes. Choosing a start-up tube set is where many Elekit customers begin their tube-rolling journey.

The Elekit's four tube-set options begin at $365, for two Cossor/LinLai Delux 2A3s and two Sylvania 12BH7As, and top out at $1525 with a matched pair of Western Electric WE300Bs (with a 5-year warranty) and two US-manufactured Sylvania 12BH7As. My review sample came with one of the middle options: two Cossor/LinLai WE300Bs and two made-in-England Brimar 6087/12BH7s for $625.

Altogether, this makes my TU-8900 a $3905 stereo integrated amplifier specified to output 8Wpc with 300Bs. With 2A3 tubes, it is specified to output 3.5Wpc. Both specs are at 10% THD.

Every single-ended tube amplifier, no matter how much it costs, starts with a simple one- or two-stage voltage-amplifier/driver circuit, which is usually one of several old warhorse circuits executed anew, with maybe a rectifying or tube-biasing twist and some fashionable upmarket parts. Or it can be an old warhorse with premium bits tweaked up to something even more lucid and authoritative by the addition of premium-quality transformers, like the TU-8900 I'm describing here.

The two-tube, three-stage circuit in the TU-8900, which was designed by Yoshitsugu Fujita, is a variation on a time-honored classic that every DIY tube person has encountered in schematic form. The TU-8900's circuit differs from that of the TU-8600, which I reviewed in Gramophone Dreams #27, in that the '8900 eliminates the high-gain 12AX7 voltage-amplifier stage. In the TU-8600, one section of a 12AX7 dual-triode is capacitor-coupled to a paralleled 12AU7 twin triode, which in turn is capacitor-coupled to the grid of the 300B. Because the TU-8600 applies cathode feedback to the 300B circuit, it requires the additional drive of a paralleled 12AU7 and the additional gain of the 12AX7.

Because the TU-8900 does not use cathode feedback, it utilizes a different classic circuit, in which one section of a 12AU7 medium-mu triode is direct-coupled to the other section, which in turn is capacitor coupled to the grid of the 300B. That joining is where the expensive Audio Note silver-foil cap is used.

On the main circuit board, beside the left channel's blue-green LED, is a jumper that allows users to add or remove the TU-8900's 8dB of negative feedback in order to add or subtract gain and adjusting the sound character of the amplifier.

Also hidden behind the easily removeable front panel are two rectangular jumper-equipped bays that permit users to adjust the amplifier's gain and output impedance of the ¼" headphone output to match a wide range of headphones.

For a while after the TADs left, I was disturbed by how compressed and clock-radio small my Falcon Gold Badges seemed in comparison. The Falcons put out an expansive soundspace but with no weighty presence or crisp details in the shadows as there was with the TADs. To their everlasting credit, the Falcons remained unsurpassed in tone truthfulness.

I'd been happily using the Elekit TU-8900 for at least five months and never once thought to disconnect that 8dB of feedback—until the TADs left. It's probable that the CE1TXs worked as well as they did with this amplifier because the feedback slightly raised the damping factor. But after two days back with my LS3/5as, I got the discontented urge to change something, so I disabled the Elekit's feedback.

I presumed that the effect of eliminating the Elekit's global feedback would be subtle; instead it was obvious: A tense haze of grain and texture disappeared, replaced by a darker but more relaxed and vibrant presentation. I immediately got the sense that I was listening to a rawer, less filtered version of recordings.

Ever since I met Victor Kong and discovered the Elekit brand, at AXPONA 2018, I've been using a version of the TU-8600, first the TU-8600R, then the TU-8600S (with higher-nickel Lundahl outputs). Both of those amps delivered an appealing SET sound that emphasized what I considered the proper amount of 300B tube clarity and illumination. While I rarely paused to notice it, the TU-8600's naturally bright demeanor was accompanied by a faint, misty grain I assumed was caused by the electromagnetic impact of its solid state rectifiers.

I noticed some of this grain in the TU-8900 with feedback, but it was overwhelmed by the dramatic 3D vibrancy generated by the '8900's amorphous-core outputs. This enhanced vitality was so pronounced that I sometimes felt it was too much—that the amp was bamboozling me, making recordings sound better than they actually do, or should.

Then it hit me: What I was experiencing—the thing that was so dramatically different than the sound I had gotten used to with the TU-8600s—was probably the effect of the TU-8900's new circuit with no cathode feedback. Well, partly that. More likely, it was that combined with those amorphous cores, the silver-foil capacitors, and the top-quality resistors.

It's important to note that these amplifier-circuit ingredients, which are not free, do not enhance the TU-8900's character. Best I can tell, what they do is eliminate material contaminants and time-domain disturbances that prevent the weaker parts of the raw signal from getting through.

After listening for months with Victor Kung's parts-curated TU-8900, I can state with conviction that this kit delivered the nuance, intensity, and dramatic transparency of big-name 300B amplifiers costing many times its price. My long-serving, much-beloved TU-8600S does not reach these heights.

Footnote 1: EleKit, EK Japan Co., Ltd., Tofuro-minami 2-19-30, Dazaifu-city, Fukuoka, 818-0105, Japan. Tel: (81) 92-923-8235. Web: North American importer: VK Music, Vancouver, British Columbia, Canada. Tel: (604) 931-8844. Web:

Footnote 2: See


georgehifi's picture

If you keep your head, and keep it simple.

I traded in a new unassembled TU-8500 kit preamp of Elekit's, the owner couldn't face it when he saw the bags of parts.
I can say that even though very plain looking the parts content were 1st Class. So instead of selling it when things were quiet and the wife was away, I decided to assemble it.
They are very well thought out kits, with clear and concise assembly instruction, if you can solder and don't rush and have a patient demeaner, you will be able to build these kits.
I did bench measurements on it afterwards, and it was as good as any $$$$$ tube preamp I've measured from the big esoteric names.

BTW: just go with the basic $1945 kit, it will sound very good, instead of the glitz and glamour upgraded $3280!! (without tubes)!!!

Cheers George

Vinylleroy's picture

If I understand it correctly. All the upgrades you did on this KIT are not available via the Elekit website, but came to mind by the Elekit distributer?

Kind regards,

Herb Reichert's picture

that is correct


Vinylleroy's picture

for your reply, and excuse me for posting my reply 5 times. Is this a Kit that can be build by someone with no experience building kits at all?

And thank you for picking out these gems and telling us about it.

Kind regards,


MatthewT's picture

The manual is very well done, tons of support on DIYAudio, and Mr. Kung is very easy to reach for help. Give it a try!

Herb Reichert's picture

Successfully building your first kit requires both hand and mind skills.

If you can build a plastic airplane model and you can complete a jigsaw puzzle

it will be the same kind of fun


vkmusic's picture

Is this a Kit that can be build by someone with no experience building kits at all? long as you read and follow the manual step by step.

Ortofan's picture

... with other tube-type power amps available for around $4K, or less, such as the Rogue Atlas Magnum III, the PrimaLuna Evo 200 and/or Evo 300 and the Cary CAD-120S MKII.

Again, particularly when there are reviews of such low power output amps, could the reviewer use an oscilloscope to determine whether or not the amp is ever being driven into clipping?

vkmusic's picture

if you want to compare which amp has good value. Here is the simple math.
You can add the cost of a pair of LL2785c amorphous core output transformer (5.4KG) + a pair of Audio Note silver 0.1 (600V). It is more or less 50% of the total cost.. There is no amplifier in the market at this price range will offer you Audio Note silver cap or Amorphous Core output transformer.

The amorphous core is a 5.4kg opt...
DIY kit does not have high markup...

TU-8900 uses an over spec output transformer. Clipping is very common in low cost amp. When an amplifier signal makes the amplifier try to produce output voltages that are beyond its capability, which is what causes the clipped signal.

Ortofan's picture

... output transformer with a core made from HI-B steel?

johnnythunder1's picture

use transformers made from "hi-b" steel ? I would think a transformer's metal is only as good as the thought behind its windings in the same way that an alnico magnet doesn't guarantee a nice sounding speaker.

Ortofan's picture

... specifies the use of that type of core material in the construction of their output transformers.

vkmusic's picture

LL2785C AM is amorphous core (for TU-8900). If it is a steel core LL2785c (no AM) it is $250 cheaper.
TU-8600S is using steel core not amorphous core.
LL2785C AM is a custom made for TU-8900.
I only want the best and afforable parts.

georgehifi's picture

"Is this a kit anyone can build"

As I said in my first post:
"if you can solder and don't rush and have a patient demeaner, you will be able to build these kits."

If you can't solder, stay away you'll make a mess of it.

Cheers George

taipan254's picture

Herb - great write-up. Why did you use a preamp here? Isn't this considered an integrated amp?

Thanks from a fellow Brooklyn-ite!

georgehifi's picture

Sort of, it's "really a power amp with a passive volume control" at the front of it. Similar to the 8600 and his others

Looks like the headphones are driven from the speaker outputs

Cheers George

vkmusic's picture

The headphone is tapped to the OUTPUT Transformer with 3 resistors
You have an option to run TU-8900 as an integrated amp or power amp with a HEX socket..

Herb Reichert's picture

the TU-8600 and the TU-8900 have enough gain to possibly (with the Heretics) skip the pre but it has only one input and I use three sources.

I have never used either of them as an integrated, but I am certain many do. You should speak to Victor Kung about this.


JRT's picture

I have not seen the schematic for the TU-8900. Looking at the schematic for the TU-8600, the secondary windings on the output transformers have taps for 8 Ohm and 5 Ohm nomonal loads, and are single ended outputs with both channels referenced to a signal ground that is also referenced by both channels' single ended inputs. Though routed through a switch to select between taps (higher/lower Z) and through switched contacts in the headphone jack (1/4 inch TRS receptacle), the outputs remain ground referenced single ended with unbalanced impedance at the terminations into the rear panel output connectors.

Each of the two (stereo) ground refenced single ended outputs could be attenuated through a simple two resistor L-pad attenuator (voltage dividing network) using low noise noninductive resistors of sufficiently high power dissipation to feed into the ground referenced single ended input of a downstream preamplifier and amplifier, which if sufficiently low in noise and distortion, the seemingly desirable euphonic nonlinearities added by this tube amplifier would dominate well above the vanishingly small linearities added downstream.

The resistors in the L-pad can be selected to provide suitable load on the secondaries while also providing suitable attenuation of the signal, while signal level into the tube amplifier is optimized for low noise and low nonlinear distortion. The downstream power amplifiers can be selected to suitably drive the loudspeakers at outputs well above what the flea power 2A3 triodes can deliver.

With 2A3 triodes installed the amplifier is rated at 3.5W per channel at 10% THD, and presumably very much lower distortion at half (-3dB) of that power output.

5.29 Vrms across 8 Ohm load for 3.5 Wrms
presumably using the 8 Ohm taps

3.74 Vrms at half of that power

0.374 Vrms is -20dB relative to 3.74 Vrms

+3dB is useful headroom for intersample overs in the top couple of octaves, and 10% THD would not be horrible on those brief maximum peaks, especialky considering that much of the nonlinearities would be in ultrasonic frequency spectrum.

With the DAC fed a pink noise signal at -20 dBFS signal level, and an AC voltmeter measuring output across loaded 8 Ohm tap on the outputs, the volume control could be adjusted to output 0.374 Vrms. That would place 0dB at 3.74 Vrms, and there would be +3dB headroom above that where THD would rise to 10%.

Those would be target signal voltages entering the L-pads. Target output voltages need to be determined, likewise the design load impedance. Using that aforementioned -20 dBFS pink noise signal, the volume knob would be adjusted to the target signal voltage at the output of the actual L-pad as-built.

So then what load impedance? The headphone circuit including headphones, exhibits a load impedance that can be varied between the limits of 13.5 Ohm minimum and 15 Ohm maximum, applied to the output transformer secondaries at either the high-Z 8 Ohm taps or the low-Z 5 Ohm taps. That load impedance will reflect back to the primaries approximately as the square of the turns ratio, so load impedance on the secondaries affects the loading of the output triodes. The output power is low enough that the designer was not constrained much by considerations of excessive power dissipation, rather presumably designed that load impedance in the interest of optimizing sound quality
via the headphones. So perhaps similar load impedance target might also be selected for the L-pad for sinilar reasons.

The inverse of the RMS of the inverse values of the two limits would be:
So maybe a good approximate target for the L-pad sum might be R1+R2= 14.2 Ohm.

The idea of hybrid amplification to boost the output of flea power tube amplifiers is not new.

georgehifi's picture

If you have enough volume with a passive pre you'll get a better sound, because there's no need for active preamp components that have even more gain/distortion/noise etc only then to knock it all back down again to the passive pre's level

Cheers George

JRT's picture

In his review of the Schiit Freya Plus, Kalman Rubinson did not prefer the non-buffered passive preamplifier mode, rather Kal clearly expressed a preference for unity gain buffered output. He supposed that might be attributable to driving relatively long line level interconnection cables between preamplifier and amplifiers in his system. In support of that, consider that buffered output mode presents a low source impedance into the cable capacitance and the non-buffered output of the passive attenuator presents a high source impedance into same.

Schiit Freya S and Freya Plus are similar preamplifiers, each having remote controllable stereo pair of 128 step stepped attenuators, relay switched R-2R resistor arrays, and with three operating modes, non-buffered passive, buffered with unity gain, and buffered with gain. The Freya S uses solid state for the latter two modes, while the Freya Plus uses solid state for the buffered unity gain mode, and octal (eg 6SN7) tube based gain stage for that third mode.

There was also a third variant of the preamplifier which is now an obsolete product, the Freya N which utilized less expensive noval tube types instead of the octal tube types. There are a few of those available at a discounted sale price from the Schiit outlet.

Both current versions of the preamplifier include balanced and unbalanced inputs and outputs, and include conversion of single ended unbalanced impedance input to symmetric differential balanced impedance output in the latter two modes. The passive mode is a little different in that because there are no active amplifiers in the passive mode for that conversion, or transformers, so rather in the passive mode the preamplifier converts the single ended unbalanced impedance input to an asymmetric differential output with the audio signal on one leg of the balanced impedance output, and with zeroed signsl voltage on the other leg (rather than the mirrored signal voltage that would be exhibited in symmetric differential output). In all cases single ended unbalanced impedance inputs pass to single ended unbalanced impedance outputs, and differential balanced impedance inputs pass to differential balanced impedance outputs.

windansea's picture

This might be one of my top 5 Stereophile reviews ever, one which I will re-read several times for the sections comparing zero feedback against light feedback. Love the observations and the prose, and the addendum on headphones listening. Art Dudley is reading this one from heaven.

There is one extra element that I would have liked: if Herb had recruited a friend to switch the feedback jumper a few times, just to verify that he was hearing something differently. Better yet a clueless friend who has no idea what the jumper switch does. I'm thinking once per day, hey neighbor can you flip this switch to up or down every day, write it down but don't tell me, for one week. That extra effort would have taken this wonderful review from a beautiful and probably accurate piece to a beautiful and verifiably truthful piece.

Lastly, I want to buy an Elekit now. Thanks Herb for a classic review!

LouisB's picture


I recently bought the kit without having any experience of building an amp before, but after reading all the feedback figured that this was my only way to a really high quality 300B/2A3 tube amp, and I chose to trust the experience of all the builders on DIYaudio and Herb's reviews with the 8600 and 8900. I was torn between permalloy and amorphous core transformers as I hadn't heard AC before but in the end wanted some of that esoteric magic so went for the 8900 with amorphous core transformers. I had to buy a soldering iron and practice soldering (a lot) before beginning but the manual is very clear and all the resistors and caps are labelled on the board (once you figure out how to read the colour codes of resistors... ). I built it in two days with only one or two fiddly bits. The box pins and volume pins, for example, are very tight and I was trying to avoid any solder bridges etc. so real took my time to double check all the joints. In the end I powered up accidentally as the power button was pressed on... It lit up and nothing exploded!

I didn't get the upgraded resistors and AN caps, I went with all stock so I can gradually replace parts and hear the differences.

It sounded great from the start. I only have a few hours on it and the immediacy, intimacy and clarity are present and will improve. No fancy tubes yet. The emotional connection that I associate with tube gear is developing and my system is not yet set up to get the best out of it. My speakers are studio monitors and need current to bloom. There's not a lot of gain on the amp (only one gain stage) so the volume needs to be cranked to get music to flow, but there are so many options and pathways to improve and know that the amp will deliver as I upgrade and discover silver or tinned copper caps and high sensitivity speakers and passive or active preamps...

So yeah I'm happy so far... Feels like the beginning of a relationship...

S_Procee's picture

This, really, great sounding amplifier can be further improved by applying pieces of adhesive bituminous foil, the stuff used for cars e.g., on the bottom and sides of the main chassis and on the transformers cover. This results in less upper bass bloom hence deeper bass, and a cleaner overall sound. Just tick your fingernail on the casing and when that sounds bright and metal'ish apply more damping until it sounds dull. Although some sources on the internet warn for overdamping, which might be true for equipment relying on vibration i.e. speaker and turntable, I can't think of a risk in applying too much damping in an amplifier. This with the exception that you'd block e.g. the cover by a too thick layer. The cost was less than 15 euro (for one 50x50cm sheet of 3M foil).
Enjoy! this amp is a delight, I use it with EML 300B and 12BH7 tubes non-NFB; PAP trio 15H1 open baffles and Music First Classic 2 TVC. The latter controlling input and volume with the TU8900's VC at 100% so effectively shortcutting the amp's potentiometer.