Background
The following is a review and comparison of the Eddie Current Balancing Act and the Super 7. Craig Uthus of Eddie Current has been nice enough to lend Anaxilus and me the 2A3 and pre-production Super 7 for two weeks. Over this weekend, we also invited CeeTee down for a micro-meet to play with these toys. I've been trying to get him to spend more money. This is essentially a joint review with us comparing notes and me (Purrin) taking the lead on the write-up.
Equipment
DACs: Benchmark DAC1, PS Audio PWD
Headphones/IEMs: UERM, HD800, AD2000
Balancing Act
The Balancing Act (BA) could possibly be the best headphone amp on the planet - we at least believe that it's the best we have ever heard (I haven’t heard the Pinnacle, LF, or the Woo mono-strosities yet though.)
@Sachu: Since I know you are probably going to pop up here, feel free to send us a Liquid Fire for evaluation.
When I (Purrin) first took delivery of the BA, I stayed up until 2:30am every day for two weeks listening to it. Even now, every time I put on headphones powered by this amp, it’s always a "Holy <expletive><expletive> <expletive> Batman!" moment. There are only a few headphone amps that I’ve heard or owned that can compete in the same league: The WA5 (fully upgraded) and Apex Peak/Volcano (P/V).
The BA is priced at $3950 with new production EH 300B tubes. This is a steal when you compare it to some of the $10,000 amps out there. The WA5 is $4780 with the full upgrades including the Shuguang rectifier tubes. On that note, the BA does not need any fancy rectifier tubes. I rolled some TungSol 4x6WA to replace the stock rectifier tubes with no effect.
Much has been made about its soundstage - which is unsurpassed. I would refer readers to Ryan Clarin’s review on innerfidelity regarding the soundstage capabilities of the BA: http://www.innerfidelity.com/content/eddie-current-balancing-act-page-2
Supposedly a lot of the credit for this goes to the high-frequency AC heater for the filament of the DHTs. No other headphone amp I am aware of takes this approach. (Someone please correct us if we are wrong.)
There are a couple of things however that we wanted to add about the soundstage. It’s not just soundstage width or depth as most of us typically think of it, it’s also the more subtle aspects of such as greater depth, precision layering of sound, and instrument separation. Musicians and instruments don’t come out flat or as one (or two) hazy blobs - they become distinct and three dimensional. This in turn affects all other aspects of the listening experience. The best analogy we can make is like how with HDTV, the elements in the picture just sort of pop out at you with better contrast and more vivid color.
The BA takes only one 6SN7 as the driver tube, which is nice because it alleviates the need for matched pairs. Two output tubes are used - the BA reviewed here was one that could take either the 300B/PX4. 2A3/45 and PX4/PX25 versions of the BA are also available. As of right now, there is only one good current production PX4 tube, and that is the KR PX4. The Sophia PX4 is a piece of junk - it lacks the richness of the KR. More importantly the Sophia lacks bass. Craig has indicated that the Sophia PX4 was really a 45 tube (same plate resistance and gain) disguised as a PX4. Comparisons of the pictures of the Sophia PX4 and Sophia 45 make us wonder. Finally the Sophia is not really a mesh either, more like a solid plate with little holes punched through it. In contrast, the KR just has much better tooling and looks to be much better constructed.
With a neutral driver tube such as the Tung-Sol Black Glass Round Plate and PX4 output tubes, the BA is a very clear sounding neutral amp with incredible speed and explosive bass. It’s almost solid-state sounding, but with the inner resolution and soundstage of tubes. One thing we noted comparing the BA to the 2A3, the Super7, and a few other cheap solid state amps we had lying around was that the BA is a very fast sounding amp. It’s scary fast given that it uses tubes.
Because most of the combinations of DACs and headphones that we were we running, we used the EML 300B solid plate output tubes to thicken things up a little bit. The EML300B is still fairly solid state sounding in the bass - tight and fast - just a slight departure from the PX4. More bloom in the midrange, not as clear sounding, and not as rich in the treble as the PX4. By the way, if we wanted a more classic lusher tube sound, we could have gone with the TJ Full Music 300Bs. The BA is still smooth and liquid sounding in the treble no matter the output tube.
The BA is by far the most dynamic amp I’ve heard, better than the Peak/Volcano which no slouch in this area either. The dynamic capabilities of the BA are excellent from throughout the entire audible range. The BA’s resolution and ability to extract low level information is also excellent. Whereas the Peak/Volcano is more analytical in this regard, the BA is more subtle. The P/V brings out micro-dynamics to the forefront. Personally I (purrin) prefer the BA more because it lets us concentrate on the music instead of the details. In fact – the BA forces us to listen to the music. The BA still gives to us the choice to examine the detail if we wish - but the BA always maintains a vector towards the musical performance.
Besides resolution and dynamics, there are important, subtle factors that really set the BA apart. These are much more difficult to describe because they are more commonly heard only on the "good stuff". The BA has a very immediate sound - of bringing us there to the performance and "in-time." It’s got a sense of authority and ability to dig into the music - that is of being able to instantly swing the intensity levels of sound in a way that’s very expressive. Perhaps the “phrase instantaneous dynamic-contrast” is a good way to describe it?
The BA provides us a continuity of volume levels - an infinite number of shades - very high granularity. This is akin to how a good CRT monitor or film projection screen is able to render to all shades of grey and dark rather than wash or blacken everything out (like on an LCD, especially the older generation LCDs.)
Finally the BA does have few weaknesses. Nothing is ever perfect. The bass is a little bit rounded - not as controlled nor tight compared to certain amps, i.e. (Apex Peak/Volcano, Dynahi, etc.) Do we miss this aspect of bass control? Yes, but the BA gets reasonably close enough and does so many other things better which suites our priorities. Some people may find the overall liquidity and treble smoothness of the amp unrealistic. The BA is not as analytical as certain amps. And the BA is not as lush and romantic sounding as would be expected of a tube amp. Finally it can be extremely costly to roll output tubes. The best 300B, PX4, and PX25 tubes can be extremely expensive.
Super 7
We listened to a pre-production version of the Super 7 (S7) with the Transendar E-I transformers. The production version will have Electra-Print E-I transformers of the same specifications. The winding techniques and dimensions will be slightly different and Craig expects the Electra-Prints to be slightly better (if this is even noticeable to the average person.) There should be no change in tonality.
The S7 will also have speaker outputs for powering small or extremely efficient speakers. Below is a picture of the footprint of the amp. It will be nicely compact with no external power supply or umbilical needed. We'll upload photos in a couple of weeks when the chassis parts come in.
The S7 will utilize one input tube and six output tubes. A lot of people don’t realize how awesome this is: Instead of letting the amp designer voicing our amp and then us having to find tonal synergies with other components, we can now do it ourselves! It is even even possible to do it for cheap with very good sonic results - for example consider the following output tube combos:
- Warmer sounding combo 1: 2x Ken Rad VT-231 black glass, 2x Sylvania GTA chrome-top, 2x TungSol new production
- Warmer sounding combo 2: 2x EH new production, 2x 7N7 tall glass, 2x Ken Rad VT-231 black glass
- Leaner sounding combo 3: 2x 1578, 4x TungSol new production
- BA (with EML300B) tonal emulation: 2x 1578 4x Sylvania GTA chrome-dome
We found that mixing different types of tubes can add some “complexity” and makes thing interesting - like a fine wine. According to Craig, there is no need to get precisely matched pairs of output tubes (unless one tube is about to die) because they self-adjust individually.
The S7 will have much more flexibility and range of tonality compared to BA (it can get leaner/brighter and warmer/darker) than BA. Or at least we should be able to tweak things for much less money given the current availability of old-stock and new production 6SN7 and variants.) CEE TEE adds that the source also contributes a lot to the sound and this can be heard through the Super 7 and BA with ease. Imagine just getting one amp - and that’s it. No more amp-changing when you get new headphones or new DAC - just roll tubes first...
During our micro-meet, once we tweaked the S7 to get a tonal balance eerily similar to the BA (with a 7N7 tall glass driver and EML300 solid plates), we found it surprisingly hard to tell the difference from the BA with quick listening back-and-forth. Closer examination can reveal the following differences though:
- BA gap on soundstage was still evident. The BA soundstage was less artificially wide, much deeper, more precise, lacked gaps, and had a better defined center.
- The S7 was surprisingly resolving (could keep up with BA with the PSS transformers - 90% as good.)
- The expressiveness of the S7 is not as good as the BA - the shades of volume/dynamic levels were fewer. The S7 did not have the ability of the BA to instantaneously jump between these "intensity levels". But then again - it was so very close!
- Overall the BA sounded a bit more refined: smoother, more relaxed, more liquid, more cohesive, better at low-level detail retreival/control and clarity, and a tad more dynamic. More of the msuical "note/tone" is present at all times.
Basically the S7 does all the major things right though. And this is not very common. The S7 is not just "better than other amps" priced below it (and some above it), it’s not just an “incremental” upgrade (like going to the LCD3 from the LCD2), the S7 simply obliterates everything below it that we’ve heard: Lyr, Burson, Red Wine Audio, WA6SE, etc. To us, the S7 (along with a few other amps) represents a minimum level of capability that is required for a headphone amplifier.
If priced below $2000, we would consider this an amazing deal. Anyone who got one early at $1300 basically stole it.
ALERT: As far as we know, anyone who is on “the list” is still eligible for the introductory price of $1300. After a few more weeks, this introductory price will be gone forever.
Q: Didn’t you say you were also going to review and compare the 2A3?
A: Yes, but JPnums already wrote a great review: http://www.head-fi.org/t/547564/review-eddie-current-new-2a3-45-headphone-and-speaker-amp We agree with his impressions and decided we couldn’t write anything better. Also, we didn’t get the tubes we ordered in time for the 2A3, so we couldn’t tweak it with our setups. If we were able to spend some time go get things just right, or right enough, we would have supplemented JPnums review.
Q: Aren’t you just being overly critical and a hater (of other amps)?
A: [Purrin] No, I like the Peak (with Volcano PS), the WA5 (fully upgraded), the EHHA (DIY), and the A47/CMOY. I also like the B22 and Dynahi. [All] If an amp is going to severely distort the output of the source, or be incapable of sounding better than the built-in output of the source, then it’s not worth buying – no matter the price. We would just prefer to use an iPhone and good IEMs (JH13, UERM, ES5, etc.)
Q: I heard that the Eddie Current amps use cheap parts and had bad soldering jobs. Is this true?
A: We opened up all three amps we had on hand and didn’t see any bad soldering jobs or wires that were about to come off and fry something. Other than the S7 which is on a PCB, the 2A3 and BA are hand-made with point-to-point wiring. Things happen sometimes with point-to-point wiring and stuff made by hand - see this thread on the Leben: http://www.head-fi.org/t/575746/lebens-owners-request-what-i-found-inside-my-leben-cs-300x-limited We would definitely like to hear from any other owners of Eddie Current amps if things have been improperly soldered or blowing up.
As for the "cheap parts", last time we checked, the Electra-Print E-I output and Cinemag line level transformers weren’t exactly cheap. It’s true that Eddie Current does not use expensive “boutique” caps or parts, e.g. it appears there is a Solen serving as the interstage caps on the BA. I don’t think Eddie Current offers “supreme parts upgrade packages”, but you can always offer to give Eddie Current another $1150 or something to upgrade those to a V-cap and the PS caps to Blackgates if it makes you feel any better. (Eddie Current may still refuse.) I’ve given thought about swapping parts myself, but I’m happy with the voicing and don’t want to mess with it.
Q: I’ve heard with initial impressions of the S7 that was a little bit rolled off and dark sounding?
A: This is not true. We believe this was due to the source (and Patricia Barber Modern Cool CD recording) at the Venice meet where we heard an early prototype of the amp. During our micro-meet over the weekend, the S7 had no issues with treble extension and treble volume using the PWD and Benchmark DAC1 with various recordings.
Q: Can I get the HD800 to sound (on the S7) more lush and more like how you originally described at at the Venice meet?
A: Yes. See the “warm tube” combos above. We felt the S7 had more latitude (or at least it was cheap) for changing tonal balance.
Q: Can you recommend specific tubes or tell us more about S7 tube rolling?
A: Absolutely not. Your source equipment, your headphones, and your preferences may be different from ours.
Q: You didn't cover treble or bass extension with these amps.
A: We didn't cover it because it's not an issue with either of these amps.
Q: Did Eddie Current pay you guys or give you any special treatment?
A: Anaxilus and Purrin know Craig in person. We did get special treatment in that he allowed us to go to his place and steal his amps for a few weeks on two occasions. We paid list price for all his amps. No discounts were available to us.
Edited by purrin - 11/6/11 at 9:44pm
