Elekit TU-8150 6V6 6AQ5

Click pics to enlarge. Right, atop my Wavac MD-811.

Review: Elekit TU-8150(DX), Part I

Update: Part II (Triode vs Pentode; Input 1 vs 2) and Part III (Small Loudspeaker Matching) and Part IV (Input 2 mod) have been published.

Being a long time Elekit fan, I own many of their products and have written a lot about their more recent offerings in my Blog. Should you be interested, here are some links:

Overview: Elekit, Part I
Elekit TU-8500 Full-Function Preamp
This article contains a 6V6 Overview

Imagine my delight when I learned about the new TU-8150. Beside 300B, my TU-8300 can run all sorts of common pentode/tetrode/beam tubes but that does not interest me. IMHO, none of those tubes (including NOS) run as triode can hold a candle to 300B (even current production). So, why does the TU-8150 interest me? Because it can use one of my absolute favorite tubes, the even more lower-powered 6V6, which neither the TU-8300 nor the TU-8200 can. If you run through my blog, lately I have been using vintage 6V6 push-pull amps, and I have been clamoring for a 6V6 SE amp, which I have heard to good effect before (here).

I immediately rang up and ordered one from Viktor of vkmusic, and I got the amp in 2 days. If you are in North America, buy from him, a die-hard supporter of Elekit who has contributed much to the company, who also offers reliable technical support.

This Flyer summarizes the Features of this amp:

DX version  Note that vkmusic supplies the kit as "DX" version, with the following upgraded parts: 1) Amtrans AMRT carbon resistor set; 2) 2 x Amtrans AMCO 0.1 for the Coupling Capacitors. And this is the version I built.

Building the Kit Like all Elekit's, building the kit was not difficult. The manual is beautifully illustrated and logical. Note: 1) the only difficulty I had was soldering the thick metal tabs that anchor the frames of the output transformers. My 40W solder, even temperature-controlled, was just not powerful enough, and it took me several attempts; 2) be careful with soldering the loudspeaker binding post - I had it upside down and had to redo it; 3) vkmusic's upgraded Amtrans resistors are longer than the stock resistors; Victor advises kind of an S-bend to shorten the distance between the legs so as they can be stuffed onto the board, but I found that too elaborate, and just bending the lead right where it exits the body does the job for almost all of them. I had it finished in a couple of days over the Lunar New Year.

In the above pic, note that the 6V6 socket modules are idling. Also note that the board uses pins which one inserts into the main board. The unit shows the 6AQ5 board installed. It is actually below the top board, which is just for anchoring and leveling with the taller 6V6 socket. Look carefully and you will see 3 levels where the sockets are.

Listening (6AQ5)

• Tubes I did a lot of initial listening using the 6AQ5, which is a smaller tube with similar electrical characteristics to the larger 6V6. The stock pair are very late production GE 6005's (note different vendors have different tube options). For the 12AX7 I used an old D-getter RCA grey-plate in lieu of the stock JJ.

• Jumper It was set to Elekit-recommended Ultralinear. The jumper's plastic handle felt loose but I was assured by VK that it is OK, as the same jumper has been used a lot in other models without any problem.

• Op Amp  Op amp was the stock NJM4580D.

• Power Socket Note that the Power Socket is the Figure-8 type (C7/8) which some may frown upon. I used the stock power cord.

• Sound with System II As used, the system comprised the Sony XA-5400ES SACD/CD player, Technics SP-1200 Mk II/Hana EL Cartridge (report to come on the Hana), Aurorasound Vida Phonoamp, Shindo Monbrisson Preamp and YL 4-way horns (104 db). The amp wasted no time in making an impression. My attention was seized by the very good Rhythm and Pace. At first there was a little grain in the treble, which quickly decreased with time, but it should be noted at least half an hour of warm-up is required for it to sound its best. Sound with the 6AQ5 is generally very full bodied and rich, perhaps just a little homogenous - after all, the new tubes and transformers especially needed to be run in (longer than caps and parts in my experience). But given the good transient performance, all was engaging. Dynamically it did a very respectable job. To cite two examples: the audiophile favorite, stimela (track 12) from Hugh Masekela's album Hope, while not as explosive as it could be (this is after all 2.9 WPC), sounded lively, involved and full of microdynamic detail; and Yannck Nezet-Sequin's Bruckner 5th (ATMA, not particularly well recorded) sounded organic and big, as it should, much better than it had previously through earphones. By this time, I was enjoying it hugely.

• As Headphone Amp At this point, I took time to construct my AkitikA amp kit (report to follow). I moved the TU-8150 to the living room, behind my workbench, and fed it with my Linn Karik CDP. Through the AKG-701 earphone sound was luxurious and detailed. Nielsen's three (somewhat quirky) instrumental concertos sounded better than I have ever heard them in the readings by NYPO/Alan Gilbert (Dacapo). The sound was so good I actually played this CD multiple times through the kit-building period. It should be noted: 1) the loudspeaker outputs automatically disengage themselves when a headphone plug is inserted. But I think as a precaution, to make sure there is loading when the amplifier is on but headphone not plugged in, loudspeakers should always be connected; 2) Using the TU-8150 as integrated headphone amp, the volume and dynamics were respectable and sound is excellent.

• Back to System II After I finished building the AkitikA, which took several days, I re-installed it in my System II. Sound was surely a little better than before and I thought it was close to being run-in. I played the wonderful Rokia Traore's Bowmboi. While it was very good, I knew her voice was a little too smoky and that there is more delicacy and sinuous delivery to be had.

• On to System III Desiring a slightly crisper delivery, I switched to System III, comprising Sparkler S-303 CDP and Schiit Saga as Preamp directly into the Elekit. Surely, Traore's voice was how it should be. Similarly, Masekela's men also had more rhythmic snap. This was in part due to the snappier delivery of the Sparkler, and in part due to the non-euphonizing nature of the Schiit, which did an excellent job driving a long interconnect. However, on some material, a bit of shrillness creeped in when played loud. In the end, I still prefer a tube preamp. By now, I knew that I had wrung most of the performance out of the amp, so it was time to move on.

 Listening (6V6)

• Switching to 6V6 It was pretty easy. Only 4 screws needed to be removed to take off the upper chassis. Then I replaced the 6AQ5 boards and its top boards with the 6V6 boards (now only two tiers). I plugged in the pair of 6V6 I had been using in my Grommes LJ5, Sylvania smoked glass VT-107A's.

• Sound with System II Everything else being equal, the 6V6 immediately sounded cleaner and clearer, as if a thin veil had been lifted. Now, Masekela's men and Traore sounded like in System III above, yet when the music got loud there was no roughness. From this point on, I concentrated on music only and here are a few that I really enjoyed. The first was Alberta Hunter's Amtrak Blues (CD, CBS). This lady is truly legendary and her life is an incredible story (wiki entry, make sure you read it). I actually got to hear her live and at the time bought her later The Glory of Alberta Hunter on LP. Her full voice on this CD is a delight and the session men were also very well recorded. And then there is Miles in Tokyo (CD, CBS/Sony), not the best recorded of the many Miles albums, but I positively dig the player of saxophonist Sam Rivers, who only appeared with Miles in those few days but was generally credited for pushing the sound of the Miles Davis Quintet forward. And two LP's were particularly outstanding. Boulez' Varese LP (Columbia) had delectable rhythmic swing and brilliant playing, a marvel from start to finish. Zubin Mehta's Bruckner Te Deum (London) had me dashing to turn down the volume, as the masterpiece opened with a choral fortissimo on an organ pedal. Yes, the amp clipped as I had the volume too high, but I was able to finish the piece at a slightly lower, but still very satisfyingly full level.

Comments Let me cut to the chase: this little amp is now my favorite Elekit amp!

• Operation Ultra steady. I have it on all day and it barely gets warm.

• Sonics It is always hard to describe the sonics of something. For this amp, I would choose Fluent. Many tube amps are easy listening, sometimes referred to as "liquid", but that is not at all the equivalence of fluency, which mandates a good sense of rhythm and superior transparency. Nothing about the TU-8150 grates on you, and everything contributes to keep your interest. Playing disc after disc attests to the superb musicality of this little amplifier with a big heart, neigh, soul!

• As Amplifier As with most flea powered amps, particularly if you play vinyl, personally I'd use this with a Preamp to maximize the gain and delivery of the first watt. However, it will sound pretty good as an integrated amp (my System III's Schiit is essentially passive volume). Volume Knob Setting when used as Amp The TU-8150 employs an IC in its preamp section, so it is not just a passive volume knob on an amp. That said, I found not much degradation when the volume knob is maxed out - no overloading or undue hardness. Dialing back may bring a tad more refinement, but the optimal setting is likely dependent on the rest of the system. I have it anywhere between 12:30 and 3:00 Power My YL horns are 104 db, so I have no problems, even with big pieces, as you can read above. I'd think it will work well with loudspeakers over 90 db in sensitivity. Just for the hell of it, I did briefly hooked it up to the LS3/5A, but even with volume knob of both amp and preamp maxed out, there was only moderate volume; however, even then the music sounded nice and lively, not seriously compromised nor muffled, which to me means loudspeaker matching will not be too difficult in general.

• As Headphone Amp I think this shall make a very nice headphone amp. But make sure the loudspeakers are connected if you even want to pull out the headphones.

• Hybrid? The presence of an op amp in the preamp stage will turn off some tube purists. But I ask myself, do I actually heard sand? Honestly I cannot say I do. The sound is rich and creamy when it is supposedly to. I have heard many all-tube amps that sound a lot more transistory (like German Octave, not to my taste). Elekit has had a long history of using IC/op amp in their products and the designer's skill is apparent.

• 6AQ5 vs 6V6 In my listening, the 6V6 is unquestionably better. I am staying with 6V6 just because I have a large stash. Although electrically similar, the bigger envelope of the 6V6 likely confers an advantage (just as 6SN7 has it over 6CG7). However, I am equally sure the performance of the 6AQ5 can be much enhanced by rolling in older and better tubes. The suppled GE's are coded 82-52, which is from the very end of 1982, just before tube productions ceased altogether. Older 6AQ5's are plentiful and cheap and one can have fun rolling tubes.

• Power Cord The supplied C7 doesn't look very promising. The best way to upgrade would be to buy a C7/IEC adaptor and use your regular cables.

Coming Next I named this article Part I because there are more things that I'd like to test on and that will take time:

• Pentode and Triode Operation These should be very interesting to try out. Triode lowers the output from 2.9 wpc to 1.6 wpc. I think it will work for me but for most others it will be academic.

• Op Amp don't have anything other than the OPA2227 Victor sent me for the TU-8500. Victor told me it is OK to use here too, so I may try it.

• Tubes I may tube roll a bit, particularly the 12AX7. I won't go crazy about it, but I may get a few nice used 6AQ5 to try out.

• Loudspeakers I'd like to try out others, particularly my Almarro M1A, for compatibility, so readers with less efficient loudspeakers can get a better idea on what to expect.

• Power Cord Not my usual area of interest, but in this case I shall seek some improvement using either adaptor or DIY power cord (the C7 female connector is not easy to get).

• Headphones I'd like to try my high impedance (600 ohm) Beyerdynamic.

As I finish writing, I also just finished listening to Strauss' Alpine Symphony, one of my favorites. Great stuff! This is not the best version in performance or sonics, but it was awesome enough!

Note: Part II has been published.