Emmeline II, The A-10, Electrostatic Vacuum Tube Heaphone Amp – Ray Samuels Audio


ray samuels was kind enough to give me the opportunity to review the a-10 thunderbolt ii electrostatic tube preamp/headphone amp. Of course, I was very happy to oblige, as it gave me a chance to hear some serious electrostat setup, which I had never done before. as such it was actually a difficult review for me in some respects as I don’t have, nor have I ever had, any headphones or electrostatic amps. I’ve only heard them in meetings. so I don’t have a direct point of reference. As such, my comments about the A-10 as a headphone amp are really more comments about it in combination with the He Audio Jade and the Sennheiser He90 together; there is no way to separate them. As a headphone amplifier, the A-10 is for electrostats only; dynamic headphones are not anticipated.

Reading: Thunderbolt headphone amp

however, i was able to test the a-10 more fully as a preamp, instead of my krell kav-250p and compared to it, driving my sunfire signature amp (balanced) and my b&w nautilus 800 signatures . this allowed me to get a very complete measurement of the a-10 as a preamp.

Unfortunately, the comments I will make about the a-10 as a preamp will not necessarily fully apply to the headphone amp function as they use different sets of tubes. the preamp section uses two 6sn7’s for gain. the headphone section uses four 5687s to drive the electrostatic outputs. they both have in common a pair of 12ax7 driver tubes and, when using unbalanced inputs, a single 12ax7 which is used as a phase splitter to derive a balanced signal from the unbalanced source.

then, dear reader, you should see my comments in that context. what i will say about the a-10 driving the two ‘stat’ headphones is really a “system” review, and my comments about the a-10 as a preamp are really only entirely valid in that exact application. other comments:

the a-10 is beautiful and very well built (as you can see in the images above). it’s physically very large, with its two full-size chassis and, of course, top-mounted tubes require some careful placement strategies. but it’s very attractive, and the kind of thing an owner will want to see and show off.

It should be noted, though probably inconsequential, that you cannot use the a-10 for headphones and as a preamp at the same time. there is a switch: you choose one mode or another.

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I’m going to have to seriously investigate an electrostat setup. it is impossible not to be impressed. the speed, the clarity, the picture: no dynamic headphone is capable of what i heard from the a-10 driving the jade or the he90. I’ve always resisted stats for the exact reasons this review is difficult: they require a special stat-capable amp, not a regular headphone amp. but this experience has led me to believe that this is a step I really need to take. I don’t think it’s possible to get what I’ve heard from the a-10 and its headphone mates with any dynamic headphone kit. certainly the a-10 is a better sounding amp than the one i had available to test with the senn hd800, but i don’t think the a-10 alone, if connected for dynamic headphone use, would make the hd800 sound the same as good as jade audio, much less sen he90. it’s the combination of a-10 and electrostatic headphones that was so addictive.

delivery of detail that is completely absent from an aggressive treble presentation was one of the most striking features of this setup. on “why am i” from dave matthews band’s latest album some very subtle details i had never heard before were quite apparent and yet the treble was never in your face; in fact, it’s unfailingly smooth.

in fact i found it so exciting to hear “big whiskey and the groogrux king” through jade and a-10 that i actually started to really like the album, whereas on my first listen i didn’t care so much. fascinating. resolution was good enough to tell the difference between normal digital 16/44.1 and the effects of upsampling at 96k and 192k! this was amazing. this is certainly a much higher resolution than the music hall headphone jack revealed through the sennheiser hd800 or any of my beyer cans.

the a-10, meanwhile, certainly provides excellent sound for the two “stat headphones I used”. it handles both deftly: astonishingly deep and punchy lows (especially in the case of jade), and a lush yet incredibly delicate midrange, and highs that are so smooth you really have to hear them to believe them. I’ve never really heard of anything like that. I distinctly remember hearing various stax configurations and not caring about any part of their performance, but I had no complaints here, except to say I wish I had these things!

I wish I could comment more on the a-10 as a headphone amp, but as mentioned, aside from saying it sounds really great, I can’t make any meaningful comparisons. It was one of the best headphone sounds I’ve ever had in my house, that’s all I can say. I am lucky to have been able to live with this team for several weeks. Not for the financially conservative: $1,500 headphones (he audio jade) driven by a $5,500 amp: a very significant investment. but it sure sounds good!

as a preamplifier:

This is where I was able to make some qualitative assessments on the sound of the a-10. i put the lightning into my main stereo speaker, instead of my krell. the krell is, of course, a solid state amp, although it sounds pretty smooth. while it is about 10 years old, I have considered it so neutral and extensive that I never thought it should be replaced. also pictures very, very good. but the a-10 outperformed it in almost every way. it was more dynamic. it had tighter, deeper, and more powerful bass. it had a lusher, but more transparent midband. the highs were softer, but just as nuanced. it had better imaging specificity (although the soundstage was not as wide as with the krell). and so on, etc., etc. It’s not really much fun checking out a piece of gear that destroys the one you own, especially since I really can’t justify spending the $5,500 the A-10 demands. I should also note that this was using amperex 12ax7 and raytheon 6sn7wgt so not a cheap tube plugin either.

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but the a-10 is just a much better sounding preamp than the krell. and that’s really saying something – the krell is a very, very good preamplifier. one of the most interesting things is that the a-10, a tube amp, was actually quieter than the ss krell. this was a bit of a surprise to be sure. but there it was: a true silent corridor. This was helpful when playing hi-res SACD, DVD-A, and vinyl; it helped a lot with retrieving details. the krell is a true champion of detail, and i didn’t think the a-10 would beat it here, but it was just as good.

It’s fair to point out that when it was new, the krell was $3k. the a-10 is almost double. some will say it’s not a fair fight, and maybe it isn’t. but at least it’s a reference point, and the only valid one I really had, in this case.

the collection of nits

As good as the a-10 is, I have a few nits to choose from. as mentioned lightning uses the 6sn7’s for the preamp and shunts them to ground when used as a head amp. conversely with the headamp and the 5687. but those tubes are on and are “running out” regardless of which mode is being used. so the whole time i was using the a-10 as a headphone amp, i was spending hours on a couple of old raytheon 6sn7wgts that weren’t in use. looks unlucky.

and i guess there’s nothing to be done about it, but the a-10 is huge. dual chassis, on large spiked feet. it is magnificently built and very pretty to look at, but it is big. had to remove components to put it in my hi-fi speaker; takes up the space of my krell preamp and darkvoice headphone amp combined.

in short

this is not the most comprehensive review i have written, because the a-10 is a unique product. With no other electrostatic amplifiers to compare it to, I feel I have done a less than complete job with it, and for this, dear reader, I apologize. but rest assured, the a-10 is a fantastic sounding amp, albeit a very expensive one. however, if you are an owner and lover of electrostats, I can’t imagine the a-10 would not excite you. I found it exciting to listen to. I’m sorry, I’ll have to let it go.

aerial laboratory

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