Elekit TU-8200 DX Headphone/Speaker Amp Review
Jun 10, 2014 at 9:30 PM Thread Starter Post #1 of 1,441


100+ Head-Fier
Jan 24, 2009

Elekit TU-8200DX Impressions/Review



The TU-8200DX is a speaker and headphone amplifier kit, designed by Mr. Fujita of Elekit Japan as an upgraded design, with new features, to their highly praised and regarded TU-879S kit. For North American enthusiasts, the kit can be purchased directly from Victor Kung of VKMusic in Canada, which includes English instructions. The kit currently runs $725 US for the "DX" version from Victor, which includes 4 Amtrans AMCO 104 PET capacitors as well as 4 Nichikon conductive polymer aluminum electrolytic capacitors. There's also an option through VKMusic to add an additional Elekit PS-3249 USB DAC to the unit as well.

I had the pleasure of meeting Mr. Kung of VKMusic at the 2013 RMAF show and I'm really glad I was able to talk with him about his passion for DIY and the various kits as well as fully assembled products offered by him to the North America market and sourced from Elekit in Japan. I have been interested in a few of Elekit's offerings in both the distant and more recent past, including the highly regarded TU-882, which uses one of my favorite signal miniature vacuum tubes, the 2c51/396a/5670. Unfortunately I've never been able to audition the TU-882, so I can't comment on its sonics, but if you are interested here is a great review done a few years back by Skylab.

When I approached Victor's table, off to the side of the main lobby of RMAF, I was originally interested in another new and interesting offering from Elekit, the fully assembled TU-HP01 Portable Tube Headphone Amplifier, which I had only learned about in the days prior to the show. I was also hoping that he might have also brought along a TU-882 with him, but unfortunately he hadn't. Although the portable TU-HP01 sounded great with his pair of AKG's, it's output is rated too low for the pair of HD650's I took along with me to the show, so I found myself looking around the table at the other offerings.

At the time I wasn't very familiar with the prior Elekit flagship, the TU-879S, but it's newer/improved sibling struck my interest right away. For the last 4 years I've found myself spending the majority of my time at RMAF sitting at the Woo Audio table, drooling over their excellent WA22 amplifier and the way it truly represented the best out of my HD650's. That all changed this year, thanks to Victor for making the trek down from Canada to spend a weekend in a hotel full of audio nuts, cradled up against the beautiful Rocky Mountains.

After speaking with Victor for a bit, I grabbed a chair, took out my custom Headphile HD650 headphones and plugged in. Wow!! Really?? Right away there was this indescribable new sense of presence and life in my headphones that I had never really heard before. I remember thinking right away, "...wait a minute, something strange is going on here!?" So, without hesitation, I popped out my trusty RMAF audition CD, containing various tracks I've used as reference throughout the years, and placed it onto Victor's 47 Treasure CD Player/DAC, which is a really cool and great sounding kit BTW. Cycling through the 16 tracks on my disc, I was astonished and outright amazed by the sound-stage, detail, presence, and tube bloom goodness I was hearing out of this amplifier. The resonance in the lower mids and upper bass was the best I could ever remember hearing out of these cans at that time, with the sear impact and deepness of the bass playing through the HD650's being previously unknown to me. Acoustical instruments had great air and resonance. Vocals, especially female, were just breathtaking. Also, although generally disregarded with tube amplifier designs, the highs I was hearing were ever so present, being both well extended and with just the right amount of sparkle, kind-of similar to finding the right tube combination that seems to leave the highs completely intact while others do not.

As you can imagine from my initial experience above, I ended up spending quite a bit of time at Victor's table that Saturday, only taking a few minutes at the end of the show to quickly run upstairs and try to get some idea of a comparison to my beloved RMAF staple, the Woo Audio WA22.

After returning from the show in October, I spent the next few months contemplating the Elekit TU-8200. Could this Japanese kit really be as good as the WA22, at a fraction of the price and with more features? Could it really be a "giant killer" in the world of desktop audio? Or, was it more of a factor of the crazy/cool 47 Treasure DAC, or perhaps even the tubes (but unlikely because they were stock). Was it a trick my mind was playing on me, since I've really wanted the WA22 for so long and this little guy is more than half the price. Well, I came to the decision that I needed to know the answer to all of this and hopefully much more, so as soon as the TU-8200DX became available through VKMusic in late January, I ordered a unit from Victor.

The Arrival:

The amplifier was shipped, doubled boxed and with a ton of packaging to ensure safe delivery, and arrived from Canada
in about 5 business days (one was a holiday). I was surprised by the weight of the unit, it's not as light as it looked on Victor's table, so shipping through Canada Air is obviously not the cheapest, but much much less than it would be from Japan. The kit includes all pieces required for assembly, including the additional "DX" capacitors, English instructions, and 4 brand new tubes (2 Electro-Harmonix 6L6GC's and 2 Chinese 12au7's), plus plenty of packaging to keep the unit safe.






The Elekit TU-8200 amplifier includes some really cool features outlined below:

  1. Active Automatic Bias Adjustment Function
    1. That's right, no need to manually adjust the bias of the amp every time you tube roll, just plug 'n play!

  1. 3 Amplifier Modes
    1. Ultra-linear, Triode, and Pentode modes can be selected easily by simply moving a jumper into different connection paths on the PCB

  1. World-Wide Power Transformer
    1. 4 different voltage settings, switchable by a plug near the power transformer - 100V, 115V, 200V, and 230V

  1. Speaker Impedance Switch
    1. Switch easily between 4-6.3 ohm and 8-16 ohm speaker output modes

  1. 2 RCA inputs and one 3.5mm stereo mini input

  1. Optional USB DAC upgrade

  1. Loaded at 8 ohms and with a standard 6L6GC power tube, the TU-8200 can deliver 4 watts per channel in Triode mode, 8 watts in Ultra-linear, and 8.2 watts in Pentode. Banana plugs can also be used.

  1. With the help of the automatic bias adjustment feature, you can roll quite a few popular audiophile vacuum tubes in this amp, including the following:
    1. Power Tubes:
      1. 6L6GC, KT88, 6550C, 6CA7, EL34, 5881, KT66, 807 (with adapter), KT77, KT90/KT99 as well as all of the usual direct equivalents of the 6L6GC. However, 6L6's and its variants are not recommended, only the GC.
    2. Input/Signal Tubes:
      1. 12AU7, ECC82, CV4003, 13D5 as well as the usual direct equivalents/replacements of the all of these types


  1. Source: FLAC files ripped securely by myself using EAC and played through Foobar2000 using WASAPI in "push" mode
  2. DAC: Larry Moore's Ultra-Fi DAC 41 with Twin Reg upgrade installed, built in the spring of 2012 and feed with an Ultra-Fi Digital Conduit USB cable
  3. AMPs: TU-8200DX (professionally assembled using high grade German Silver Solder) vs. a Darkvoice 336se
  4. Headphones: Sennhieser HD650 - Headphile modded with Ebony/Bloodwood woodies and a Headphile Black Gold cable
  5. Speakers: 2 Energy RC-10 Rosnut Monitors
  6. Cables: Blue Jeans RCA cable and two Iron Lung Jellyfish power cables


I've spent about 5 months now with the Elekit TU-8200, which is fully burned-in, with at least ~225-250 hours logged so far and ~30 hours when I started to listen critically. I've also rolled quite a few different types/brands of tubes with this amplifier already, which have really given me a true representation of all of its many abilities. With tubes momentarily disregarded, I'm finding it hard to find many flaws with the sound coming out of this amp, at least to my ears and my preferences. It's a really great sounding DIY amplifier!

The whole audible range is there, with some of the best done lows and highs I've ever heard out of the HD650's. Now, granted I'm coming from exclusively using a Darkvoice 336se for the past 5-6 years, which is a great inexpensive amplifier that seems like it was just made for the HD650, but it does have several shortcomings, especially when compared to the TU-8200DX. I've also auditioned many great sounding amplifiers including the very excellent Zana Deux. With the Darkvoice 366se, I have rolled over 100 different types of tubes, ranging over many years and countries of origin, which has given me a solid foundation of what the Darkvoice is really capable of. However, tube rolling is much more responsive with the TU-8200, especially prior to burn-in. I find that the differences in tubes are no longer similar to cable changes, as subtle variations in tone and acoustics, but much more impactful, making my HD650s seem almost like entirely different headphones many times. Also, overall the Darkvoice is also just that, a little dark across the spectrum, while the TU-8200DX is more forward and nicely extended, which can really help even-out the "veil" of the Sennheiser 600/650 line.

The TU-8200DX is also much more detailed than the Darkvoice 336se and I'm now more confident that I'm hearing many of the nuances and details that the DAC 41 is getting out of the music. Instruments and voices just have more body/depth to them than before. The TU-8200DX also has much better separation and imaging than the Darkvoice 336se, probably mainly due to the separated channels and better components/design. The sound-stage is also much better with TU-8200DX, with some tracks I use exclusively to test this being absolutely jaw-dropping as far as width and depth; certain tubes give a truly 3D holographic image on many recordings. Now, I'm not saying that the Darkvoice 336se is a terrible amplifier, not in the least, at least for the price. I've spent a ton of time with this amplifier and it is truly great mid-fi, but it isn't nearly as refined and resounding as the TU-8200DX, but of coarse it's less than half the price and is already built.


The highs are amazingly represented by the TU-8200DX, being not only extended, but also not nearly as "hidden" as I've experienced in other tube based designs. They are still a little rolled-off, so extreme sparkle, that can not only sometimes be a bit bright, but also a little harsh to some, including me, is replaced nicely with a general smoothness to anything peaky. Violins and strings have great tone and body and cymbals have the right amount of crash and air, without being sounding too hard. Compared with the Darkvoice, the TU-8200DX has a nice open treble with much more definition.

As far as sibilance, I've been unable so far to find even the slightest hint of sibilance out of the TU-8200. There are few songs I use exclusively for this purpose, one in-particular is Alela Diane's "White as Diamonds", a folk/country artist that can be very sibilant at times. Only a few tubes in the Darkvoice 336se could really smooth it out, but with every tube I've tried so far with the TU-8200DX, I can't seem to get any sibilance at all, her voice inflections are just perfectly smoothed out every time. Very cool.

As a side note, I can be very sensitive to very bright highs, so I tend to try to avoid equipment known to be overly bright in the highs; the DAC 41 is for one, a NOS DAC and can be very laid back at times compared to OS alternatives. However, the highs out of the TU-8200DX have been just perfect for me, brighter than I am use to, but in a good, not bad way at all. I finally feel like I can enjoy high tones and even a little more brightness than I'm used to, all awhile not feeling fatigued or experiencing any pain over time; they are very smooth and refined in this regard, if not a little laid back with most tubes.

If you have a brighter source and/or headphones than mine and like sparkle in the higher frequencies, I'm sure the TU-8200DX will satisfy your needs, at least for a tube design, and if it doesn't right away, then merely switching out the signal tubes to Telefunkin Ribbed Plate NOS 12au7s, should give you more than enough dazzling highs. The Tesla NOS Blue Glass EL34s also offer some really great sparkle, but at the cost of a little less weight in the lower end.


As far as the frequency range of audible sound is concerned, I wouldn't hesitate to call myself a mid-range junkie. To me the mid-range is the most important part of the spectrum and if you can't get it right, the rest of the sound falls apart. My preference for the mid-range is also why I tend to prefer tube based gear as opposed to solid state; I just can't get enough of the natural tone and resonance that a great tube bloom can give in the mids and upper bass. So the question is, do I enjoy the mid-range of the TU-8200DX? Well, lets just say that I wouldn't have gone to all this trouble writing about this amplifier if I hadn't... it is good, really good.

I find the TU-8200DX to have a very nice open and detailed mid-range, without sounding too dark. It is in fact much more open and detailed than the Darkvoice 336se all awhile being more forward in it's presentation, which is actually a very good thing for the HD650's. If I had to classify it with just listening to it with the HD650's, I would say that it is more on the darker side of neutral in the mids, however the 650's are a little dark so this may be even closer to neutral than my impressions, that is with a more neutral pair of cans. Voices sound very natural and inviting, especially female vocals, which with the right combo of vacuum tubes can sound so silky-smooth and seductive that many times I was just blown away. In fact, what initially blew me away at RMAF was several female vocal tracks that I use to judge the upper mid-range as well as sound stage. If anyone is familiar with Mariee Sioux, Alela Diane, or Lou Rhodes, I don't think I've heard a better representation of their voice's sheer beauty than with the TU-8200DX. I'm sure you'll enjoy the sound of the TU-8200DX with your favorite female vocalists.

Of course, using different signal tubes you can really tweak the sound and tone of the mid-range of the TU-8200DX. I've really enjoyed Brimar variants with this amplifier and found that they give just about the right amount of "presence" to the mid-range. Mullards are also very good, a little laid back and probably the smoothest sound in the mid-range, but at the expense of micro-detail. The Telefunkin smooth plates are also very nice, a little less silky, but with great detail and imaging. A few pairs of Amperex have also impressed me in many different ways throughout the mids.

If you judge an amplifier by how well it does the mid-range, than I don't think the TU-8200DX will disappoint. If you find it doesn't quite have the flavor that you crave, then a simple signal tube change can really make a difference to suit your cans or speakers.


I won't call myself a "bass-head", but then again many that do enjoy a good amount of bass sometimes won't call themselves this term either, but I like bass that has weight/punch and when required resonance. However, I find almost nothing more unpleasant (even more than a congested mid-range) than either a very sloppy/uncontrolled/boomy low end or especially one that is virtually nonexistent. I will tell you that at first I was a little worried about the bass with the TU-8200DX... however, I broke the golden rule and listened to the amp before it was fully burned in, while the bass was a little soft and hasn't opened up entirely.

Anyway, at first, without much burn-in, the bass was very soft and without impact and appeared so no matter which power tubes I tried. After at least 10-15 hours of burn-in and swapping the stock EH 6L6GC tubes out for NOS GE 6L6GC, the bass all of a sudden came alive with great force and power. Now, I've found that the GE 6L6GC tend to be very bass heavy tubes, but after at least 60 hours of burn-in most of the power tubes I've tried have had a least a very decent amount of presence. Currently, slight changes can be heard between overall weight, depth, and resonance with all, but the KT66's and KT88's give a very nice forward and powerful representation. I've found that with GE 6L6GC, KT88, 6550, and KT66 tubes the bass really shines out of this amp, at times the best I've ever heard out of the HD650's. On a few tracks that I've become accustomed to, the bass is more subsonic than I have ever heard out of the HD650's, at times even seeming to tickle the hairs within my ear canal, which is not very easy to do.

Even though with the right tubes you can really get your bass fix, it has never at any time, with any tube combination been very sloppy, uncontrolled, or boomy... just always a nice variation in weight, punch, and depth that can suit many types of music. I have found that EL34's tend to be a little more shy when it comes to the bottom end than KT88s or KT66s, however they have a beautiful mid-range and probably the best sound stage out the variants I've tried thus far. The Mullard EL34s do have a very strong bass presence compared to other manufactures while the SED Winged "C" or Phillips/Amperex EL34s have very nice sound stage as well as a very open mid-range. So, once again, I've learned my lesson to just simply wait until the amp has fully burned-in.

If you tend to find yourself opting for less bass in your listening preferences you can try a pair of EL34s for some extra mid-range detail. If you like rock than maybe a pair of GE/RCA 6L6GC's will add some nice punch/drive to a more laid-back headphone/speaker. If you can afford them, NOS KT88s and KT66s will give you almost all that you may desire, with a nice forward presentation. Only a few 12au7s so far have given me a boast to the bass over the rest, with Brimar 13D5s, CBS 5814W black plate, Amperex ECC82, and RCA Clear Tops giving the most.


Unfortunately, due to close proximity to my neighbor's bedroom and the fact that they have have a little one, as well as me probably being a little too polite, I haven't been using my Energy RC-10 monitors as much as I used to. Thus, I haven't been able to properly test the speaker out of the TU-8200DX, at least as much as I would have liked to for this review. However, I can say that they drive the Energys with more than enough power for normal listening levels in the 4 watt per channel Triode mode. Now, the Energy RC-10s have about a 91 DB sensitivity rating and with the port plugs out probably a little bit more, so they are fairly efficient. If you plan to drive monitors with at least a 90 DB sensitivity rating than I don't think you'll have any problems using the TU-8200DX at normal levels and if you want to be safe, changing the jumpers to Ultra-Linear mode should give you the headroom you desire. I would probably not recommend running any large full range or monitors with less than 90 DB sensitivity.


So, does the Elekit TU-8200DX answer the question I posed to myself after RMAF? Is it the giant killer I've been looking for? Is it as good as the Woo Audio WA22?

Well, it has given my library a new fresh breath of air and has invigorated my enjoyment of the music in my life. For me it does just about everything right and all in the natural tube bloomy way I've come to enjoy. It has given me a new appreciation for high frequencies, without turning me away with bright or peaky treble. It has really opened the mid-range and has allowed me to hear more of the music contained within, all awhile providing a nice smooth and silky texture that is very engaging at times. The bass has me hearing things I've never heard before with my HD650's, sub-sonics that tickle my ears and controlled punch that is fast and also very enjoyable.

But, is it as good or even better than the Woo Audio WA22?

I wish I could honestly answer this question, but even though I really have to say that I can't, at least not with absolute certainty and for sure, the Elekit TU-8200DX has actually made me so content that I can honestly say that I no longer really care... :) If I previously or currently owned the WA22, than I think I could make an educated opinion for one way or the other. However, I've only been blessed with hearing the WA22 at RMAF briefly each year and not for very long as it is a popular attraction. If I was forced to place a bet, I would put my money on that the TU-8200DX is probably right about on par with the WA22 in unbalanced mode, to most listeners and with the majority of music. I would say that while I enjoy the power tube choices on the TU-8200DX more, the 6SN7 tube of the WA22 is just a very fun tube in general.

The real question I think one must ask themselves is what features are important to them and for what price. The WA22 is almost 3 times the cost of the TU-8200DX, although you do have to assemble the Elekit. If running balanced headphones is a requirement from a balanced source, than the WA22 would probably have to be the choice. However if you would like to use the speaker outs of the TU-8200DX and the ohm and output mode adjustments interest you, than the Elekit is a better value.

Then there comes the tube rolling options. With the automatic bias feature of the TU-8200DX, the tube-rolling possibilities are almost endless and with new production tubes in these variants, if NOS isn't your bag or too expensive, other options are available. The WA22 also takes a rectifier tube and both the tubes that the Darkvoice takes, the 6AS7G and 6SN7. There aren't many options for the 6AS7G and I don't believe many in new production, but they are plentiful and mostly pretty cheap. I prefer the openness and sound stage of the 6080 variant, but it's even more scarce for the good ones; Brimar solid cast-iron plate 6080's are nice and clear up top and very open in the mids. On the other hand, the 6SN7 were one of the most produced tubes at one time, but prices have risen in the last few years and matched pairs can now cost a little more (many are asking prices for run of the mill basic constructions that are too high). However, in general they are less expensive than the majority of the tubes you're going to want to try in the TU-8200DX. As far as NOS, 6L6GC's are a little cheaper, so are 5881's and 807's, but the majority of EL34's, and the KT series are expensive. Cheap 12au7's can be found, but nicer sounding and more rare options can go for a lot as well.

In addition, the ability to switch output modes in the TU-8200DX and even changing something as trivial as the LED color, it's not very hard to argue which has the better tweak-ability out of the two. Not even to mention the extra space on the Elekit's PCB board to add bigger and better caps if you enjoy modding.

If you're interested or experienced in DIY or have basic experience building/soldering kits, I don't think you'll be disappointed in the TU-8200DX for the price. Then again, if you aren't a DIY'er or just not completely confident in your abilities than you can always try to find someone that will build the kit for you. This is what I did and I couldn't be happier with the result. I think I'll be holding on to this amplifier for a very long time...

Side Note:

Unfortunately, about halfway through this review I managed to blow the left channel Q3 FET on the TU-8200DX... it was a real big bummer as I was just about to finish this review.

As a warning of caution, please don't try the 807 European variant labeled as QV05-25. I purchased a pair of NOS Mullards and the FET blew after about 5 minutes. I believe this variant is out of spec for this amp, with working adapters, as the plate voltage I believe is actually a lot higher than an RCA 807 or common variant. At first I thought the left tube had blown; all of sudden the left channel went dead and the LED turned purple, however later I had this pair tested and they are as NOS as you could really get... shame.

After the channel went out, I contacted Victor immediately and within less than 1 minute, that's right, less than 60 seconds later, I had a reply from him. Within about an hour I had another reply from Victor who had contacted the designer with my initial question and later that night I also received a phone call.

All I can really say is that I'm definitely not use to this kind of customer support and I can't say enough about how great a guy Victor truly is. Ever since I met him last year at RMAF he has taken so much time and care regarding my amplifier as well as all my questions. DIY is really his passion and he has devoted much of his current free time to these kits as well as the customers who purchase them. I truly believe he is doing this for the love of DIY and of music; even though he has a non-audio related full-time job, he seems to transcend these passions onto all of those who he meets.

In the end, the FET was replaced and organic caps were also installed at the same time. These caps have given the sound a little more openness, detail, and richness while keeping the natural tone as well as presence still intact; a very nice addition and recommended.

New Version:

The new version of the TU-8200 is the TU-8200R, which includes the following upgraded features:
  • Better components
  • ALPS R27 volume pot
  • LOW ESR conductive polymer hybrid aluminum cathode Bypass capacitor
  • Headphone impedance can be selected by changing the jumper location
  • The protective circuit has been improved to avoid malfunction due to tube rolling

Videos showing assembly:

Below is part 1, out of 4 parts, and there is also an unboxing and final assembly video:

How To: Assemble the Elekit TU8200R Amplifier Kit

Internal thread links to expanded info on tubes for the TU-8200:


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Jun 12, 2014 at 5:43 PM Post #2 of 1,441
Great review Mr. "Tube collector" Effusion,  I was the one who witnessed and auditioned the Kit with my Q701 at RMAF last year and Oh man, it was astonishingly transparent and new natural sounding amp that I have ever heard with the Q701. The feelings were simply incredible and I shouted inside my head : "Got to ask Victor about the price immediately 
". I was only wowed by various brilliant combos, such as 009/Blue Hawaii Se, LCD2/Violectric v200, and HD650/Crack, and Q701 and Elekit TU-8200DX is one of those. Maybe I'm probably gonna wrap one at RMAF this year. 
Jun 13, 2014 at 1:52 AM Post #3 of 1,441
Thank you very much for this extremely detailed review!
It was very interesting as I've been looking at the Elekit amp myself and currently use a DV 337 as my main tube amplifier (very happy with it, btw but of course I don't know how it compares to your 336 or to the Elekit).  To me the 337 sounds quite neutral for a tube amp, I dislike the typical so-called 'lush' tube amplifiers which to me are only indicative of sloppy design and badly driven tubes.
I'm currently working on a DIY tube project but will definitely keep this in mind, especially for the versatility it brings.  I listen mainly to classical instrumental music and like a clear sound and good midrange.
Jun 13, 2014 at 2:23 AM Post #4 of 1,441
The 337 is a very good amplifier and regarded as more refined than the 336se, but they do use different tubes and the 6sn7 makes the 336se very versatile.  Unfortunately, I haven't had the pleasure of hearing a 337, always wanted to, just no access.  Although, I would say that where the bloom in the 336se was sometimes a little "slushy", it is definitely tighter, with better layering with the Elekit; many 12au7 tubes such as the Telefunkin, GE, Westinghouse, RCA,  and Raytheon (esp. the 7730 gold pin variant for clarity) seem to provide more of a balance.
If you like the sonics that the tubes bring, but without being overly lush,  I've found that newer production, especially higher end, sound really good, with much more of a subtle bloom; almost solid-state sounding when compared to most NOS types, with generally great highs.  There are a ton of tubes you can roll with the Elekit, but even with all these options prices can be expensive, even for good new production pairs.
I've heard great things about Psvane tubes as of late, but haven't tried them yet.
Good luck on the build!
Jun 13, 2014 at 2:46 AM Post #5 of 1,441
  Maybe I'm probably gonna wrap one at RMAF this year. 

Victor did mention to me that he plans to attend the 2014 RMAF show and I'm sure he'll bring a TU-8200DX to audition again.
Same sediments exactly, great sounding amplifier, even though at the show it had stock tubes!!
Jun 13, 2014 at 3:15 AM Post #6 of 1,441
Yup! His table last year was very close to the entrance door. I didn't like the portable amp of his with the K701, and I found they were a bit harsh and sibilant. However, when it came to the tube amp, they became totally different beast. My AKG q701 pair extremely well with the amp and HD650 does too, but I did not have enough time to listen for long. I will be getting the HD650 soon and thinking about either building the Crack or purchasing the kit. I'll decide after RMAF this year.

Thumb up for your Amp, great choice. Met you last year at Denver meet and your tube collection is simply magnificent.

Jun 13, 2014 at 10:04 AM Post #7 of 1,441
Hi Ben,
I definitely enjoy the variety.... already have quite a few for the Elekit as well. 
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Hopefully you were able to audition JmanOfIsrael's Crack during that meet.  I'm not sure if it was fully burned-in, since he had just built it, but it sounded great!  Although, in comparison to the 336se at that time and with a few of my favorite 6AS7G/5998s the Crack came across as very polite, if not even a little too shy for my general tastes, albeit with a very sensual and seductive presentation of its own.  The speed and impact of the 336se was just much better, but then again this Crack didn't have the Speedball upgrade and may have not fully come into its own at the time I auditioned.
With my brief introduction to the Bottlehead, I would have to conclude that since the speed/impact of the TU-8200DX was on par if not generally better than my 336se, that it would also be both faster and have more weight than the Crack in general.  Of course, the laid-back, seductive, and rich sound of the Crack can be a very big positive at times, just really depends on the type of music you enjoy most.  I can see the Crack being perfect for Jazz, Blues, and Classic Rock, but maybe a little too slow/soft for anything produced or overly complex.
Also, I would speculate that the Crack is an easier build and maybe better suited for first-time builders, as it is point to point wiring and the Elekit does have a PCB board.  Even though I didn't build the Elekit myself, Victor did assure me that not only is it a fairly easy build for beginners with great instructions, that it is also one of the most fun kits he has ever built and I've gotten the impression that Victor has built quite a few kits over the years.  So, if you enjoy DIY and don't mind the extra hours and precision needed to properly complete the PCB, in addition to the higher price tag, and at times you listen to music that requires a little more speed as well as impact, than I think you would enjoy the Elekit.  Plus with the options for tubes, speakers, and upgraded components, the Elekit is more versatile.
Maybe Bottlehead will be at RMAF this year and you'll have the chance to compare!
Jun 13, 2014 at 11:14 PM Post #8 of 1,441
I asked Mr. Fujita our chief designer  the  topography for headphone section found in TU-8200
Here is the answer from him.
For most  integrated amps with vacuum tubes, there are not so many of them with headphone terminal in the market. Even if they have, they usually adopt an exclusive circuit for the headphone, which in most cases are solid state. These headphone circuits cannot realize pure tube sound. For the TU-8200, there is no exclusive circuit for headphone terminal. Mr. Fujita our chief designer simply connected the headphone terminal to the tube amp itself, adding only three resistors on the signal path.
This is not as simple as it sounds. Unlike solid state amp, impedance matching is of critical importance for tube amps. Mr. Fujita did not just lower the voltage to maintain drivability of the headphone but also had to carefully consider the impedance of the headphone to be connected. He finally optimized the impedance value with three resistors to deliver pure tube sound.”

Jun 14, 2014 at 1:13 AM Post #9 of 1,441
It's not terribly complicated either, you need to ensure that the headphone load that's reflected back via the output transformer matches the 'expected' speaker load which will mostly be 8 Ohm.  Check out this link to calculate the resistor values specifically for the impedance of your headphones:  http://robrobinette.com/HeadphoneResistorNetworkCalculator.htm
There's no such thing as "He finally optimized the impedance value with three resistors to deliver pure tube sound.” that can be factory set and is optimal for all headphones.
But I do very much admire the versatility of the build, that's the real challenge:  finding a good compromise.  Building a tube amp that just has to sound great with one type of tube and one set of headphones that you know the specs of is not extremely hard.
Jun 14, 2014 at 3:47 PM Post #12 of 1,441
Very interesting review from David Kan on 6moons... if you're interested in how the TU-8200DX performs with speakers and in different output modes I recommend checking it out.  Thanks for the link Victor!
I exclusively used the amplifier in Triode mode for my review and impressions, since this is the mode I'm most accustomed to, but I now think I'm going to have to try the Ultra-Linear mode as well. 
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It appears that David was also wowed by the headphone stage of TU-8200DX towards the end of his review, while using his pair of Sennheiser HD598s.  Below is a quote of his impressions:
"With my modest headphone I could hear all the tube variants in their best light*. None of them sounded excessive now, not even the Mullard EL34 in ultralinear mode. What used to be fat and bloated on the Synergy F2 now was intoxicatingly sweet on the HD598. And with the Genalex KT88, the golden piano tone and pearly touch simply melt my heart. I did try a few headphone amps in the past. This was the first time my perception of headphones was changed forever.
* High-impedance headphone vs low-impedance speaker load paints the picture. When not tasked to drive loads which push their limits, tubes will behave far more linear and sound it. Here higher impedance is clearly better. - Ed"
I wish I knew more about the specifics of the headphone output, but comparing it the 336se, which is designed solely for headphones (or as a preamp), the TU-8200DX is much more responsive to tube changes than the Darkvoice generally was.  As I mentioned in my review, certain tube changes made my HD650s seem like completely different headphones at times; the sonic differences between tubes were no longer equivalent to the subtle differences you can get with cable changes for example, but now much more impactful with the Elekit.
As far as what headphones might pair well with the TU-8200DX, it's hard for me to say from personal experience, since I've exclusively used the HD650s, but it appears that this amplifier may pair very well with an assortment of different drivers/loads.  The HD650s are 300 ohm, while David's HD598s are 50 ohm, and Ben's AKG Q701s are 62 ohm, all of which seem to pair very nicely with this amplifier.  Only time will tell as more and more headphones are tried with the TU-8200DX, but I'm thinking that it could pair quite nicely with the majority of high quality headphones.
However Mr. Fujita designed the headphone output, I'm really glad he did it the way he did.  I agree that many times amplifiers that are built with speakers in mind, tend to overlook and under implement the headphone output, seeing it as just another "feature" to add interest for prospective customers.  I can say that the headphone output of the TU-8200DX is very good, and overall the many features of TU-8200DX don't seem to detract from the sound quality of the amplifier at all.  Not only are these features useful, they appear to have been designed and implemented ultimately with sound quality in mind and at the focus.  For example, I could see how some tube rollers may have preferred to be able to tweak or dial-in the bias while rolling tubes, as some like a higher or lower settings with certain tubes, but from what I've experienced the automatic bias feature works really well.  I've already rolled almost every type/variant of tube in this amp and at no time have I felt like a tube wasn't biased correctly or that the bias control was degrading the quality.  For me, not having to worry about re-biasing the amp and at the same time being able to roll so many different types of tubes makes this amplifier extremely fun to use.
Without good design, extra features really don't mean much in the end.  The fact that the quality of sound I've been able to get out the TU-8200DX, with all the extra useful features it has, makes this a very cool design my opinon.
Jun 15, 2014 at 1:25 AM Post #15 of 1,441
In the 6 Moons article they mention in the specs that  it should play well with headphones having an impedance of 8 Ohm (!) to 1kOhm....  If that's true and you can listen at 8 without hiss AND still get decent power and detail out of the higher impedance cans then it's a real feat. 
Anyway, for the money it's almost a no brainer.  If shipping and import duties + our 21% VAT to Europe wouldn't cost an arm and a leg I'd get myself one right away for sure.
As for the changes when rolling tubes it's true that with for instance my DV 337, rolling tubes doesn't result in dramatic differences if you stick with one tube type.  A 6AS7G will sound a bit different from a 6080 for instance (difference with tubes like the 7236 or 5998 is more pronounced) but you'd be hard pressed to hear the differences between 2 brands of 6080, which -imo- is indicative of good design and a well chosen operating point.  When you mention pronounced differences when rolling, do you mean between brands of the same tube type or between 2 different types (eg between a 6L6GC and KT88)?  The latter would be logical as I assume the amp delivers a fixed B+ voltage that has to work with tubes having some wide variety in specs, you'd get radically different proportions of 2nd harmonics for instance.
Ultralinear operation is nice with some types of music, I've tried it on a couple of builds and am forever fiddling between it and no-feedback triode operation, depends on the music and my mood..and I only listen to classical, go figure.
Damn shipping cost and taxes!

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