A-10 Thunderbolt ll, Fully Balanced Electrostatic Amp/Pre-Amp
Aug 15, 2009 at 12:51 AM Post #106 of 119

Originally Posted by Audio Addict /img/forum/go_quote.gif
I got to see your amp yesterday and boy does it look sweet.

I wish it didn't cost so much to get into electrostatic headphones. Is there anyway other than the Jade,which is currently on sale for $1499?

KOSS! Amazon.com: Koss ESP-950 Electrostatic Stereophone: Electronics

That, and tons of the entry-level STAX setups, such as the 2020
Aug 22, 2009 at 5:01 PM Post #107 of 119
Serial number 2 is now in my house. I need to get some more listening time before I give it an official review (I'll post one next weekend, and from what I can hear so far, it's going to be a pretty long review, with a lot of good stuff to say), but there are a couple of things that I can say right off the bat.

First of all, pictures don't do justice to this amp. It is, flat out, the best looking headphone amp I've ever seen. I was more or less expecting a B-52 with an extra tube; while it does share some features with the B-52, it is much more refined. The rails on the sides of the components are my favorite aesthetic feature.

I'll reserve most of my thoughts on the sound for later, but the one thing that leaps out is microdynamics. Simply put, they're on a level that I've never before experienced with any audio equipment.

So far, SOOOOO good.
Aug 22, 2009 at 6:23 PM Post #108 of 119
^^ awesome. can't wait for impressions and PICS!
May 14, 2010 at 4:34 PM Post #109 of 119
I am trying to decide between upgrading my Stealth to either the A-10 or B-52.  I think the A-10 is the better pre-amp but I am not sure I want the electrostat headphones as all have our dynamic headphones.
Does anyone have experience using the tape loop on the A-10, either balanced or single ended, to drive a regular headphone amplifier?
May 14, 2010 at 5:37 PM Post #110 of 119
Hey Guys,
Having compared the B52 and A10 in my system side by side, I was extremely interested in the preamp performance.  The B52 and A10 preamp sound EXACTLY the same.  I mean note for note, exactly the same provided the input tubes are the same.
The good thing about the A10 over the B52 is that the A10 ALWAYS provides balanced output due to the use of a phase splitter (that extra tube).  The B52 on the other hand is balanced, if the input is balanced and single ended, if the input is single ended.  What you put in is what you get out.  That was my VERY main concern as I use the B52 as a preamp first and headphone amp second.
However, the build quality of the A10 is even better than the B52.  The chassis is to die for, drop dead gorgeous and much heavier as well.  Kudos to Ray for the excellent redesign.
Finally, the choice between the A10 and B52 really comes down to what headphones you want to use.  Electrostatics or dynamic headphones...pick your poison :)
I did want to put this out there in case people were wondering about the preamp sections.  Even though the output tubes on the A10 are 6SN7 in the preamp section (the B52 uses the 12AU7 family), the preamp section sound is EXACTLY the same.
May 14, 2010 at 7:00 PM Post #112 of 119
You bet!  Infact, the way it happened was when we plugged in the A10, it was using Telefunken 12AX7 tubes on the input side.  They were the smooth plates.  I was using 12AU7 Telefunken smooth plates on my B52 at the time.  So Ray and I played some music on the B52 and really enjoyed it.  Then we switched in the A10 and there was a significant difference in sound.  The A10 was quite a bit better sounding with more definition, clarity, resolving of subtleties in the music... Frankly I was stunned as was Ray.
I was like...here we go again.  I need to figure out HOW to purchase the A10.  Ray was stunned at the difference as well.  Both units were sounding so very different from each other and there shouldn't be THAT much of a difference (according to Ray).  Well, I almost was sold on the A10 and then.....
I took out Rays input tubes, the Telefunken 12AX7 Smooth Plates and put them into my B52 input section.  THE SOUND WAS EXACTLY THE SAME AS THE A10!!!  I was so happy at that point, I really can't explain it.  I was VERY relieved as I didn't want to go through the hassle of selling the amp and it's custom isolation stand and the whole 9 yards.  The difference in sound was JUST the input tubes and NOTHING ELSE AT ALL.  Sorry, but when I think of that day, I still get so happy about it.  I was on the verge of a major change because my ears were telling me what was happening.  It isn't the equipment that I am married to, but when something sounds that much better, it just DOES and there is no way around that.
Damn input tubes...come to think of it, I still need to track down a pair of Telefunken 12AX7 smooth plates with the red tips.
....tube rolling can make a very big difference.  Couldn't believe my ears that there could be so much difference in sound between a 12AU7 and a 12AX7 from the same family and same tube type! 

EDIT:  From what I noticed that day, the input tubes made the differences in the sound null between the A10 and B52 preamp sections.  I was very content at that point and never thought of rolling 6SN7 output tubes on the A10.  However, from my experience with the B52, the output tubes also have a bearing on the sound, just NOT as much as the input tubes.  I did tons of tube rolling on the input and output tube sections of the B52.  I really wanted to nail the preamp sound performance for my speaker rig.  
May 14, 2010 at 8:06 PM Post #113 of 119
Fascinating - the A-10 does use a phase splitter on the unbalanced inputs, whereas the B-52 does not.  I would think that, at a minimum, the A-10 would sound better, or at least different, with unbalanced sources being presented to the balanced outs.
Both are great sounding amps, IMO, that's for sure, although I spent more time with the A-10 than the B-52. Certainly the B-52 would also make more sense though if you want to use it for dynamic headphones - they are close enough that I wouldn't get the A-10 unless I was, or planned to be, a 'Stat guy.
May 15, 2010 at 1:41 AM Post #114 of 119
Aha, good point Skylab.  You see, my DAC is feeding a balanced signal to the B52.  Same balanced signal was fed into the A10 as well when it was here.  So my sound comparison was based on that itself.  We never fed any unbalanced signal to the A10 so I have no idea how the phase splitter tube would handle that.
For now, all my headphones are dynamic.  So the B52 stays for that.  If I was exploring or wanting to get into 'stats, I would definitely be considering the A10.  My ultimate decision would be based on the preamp performance, there I don't want to compromise if at all possible.
Nov 21, 2020 at 3:06 PM Post #115 of 119
While this is an old thread, I just put a deposit down on an A-10 Thunderbolt II from Ray. Hopefully this will be my last headphone amplifier / preamplifier ! Last year he made some internal changes to increase it's performance with Stax SR-009. I had a chance to hear then and have not been able to get it out of my thoughts.
Dec 25, 2020 at 3:20 PM Post #117 of 119
Picked up my A-10 this week at Ray Samuel's Audio.


I must say I find it a lot more natural and real than my Utopias with the Apache. I also had a chance while at Ray's to compare it to his B-52 with the Sony R10 and my Utopias on the the B52. This really is the end of the line for me.
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Jun 26, 2023 at 6:17 PM Post #118 of 119
Hey guys,

If anyone in socal (or even nor cal) happens to have an a-10 and wouldn't mind letting me demo it, please reach out! I'm willing to bring over any gear I have to let you try in exchange! Just trying to figure out if I the a-10 may fit my desires after the new b-21 blew my socks off at canjam (but I'm a tube guy at heart).

Also, sorry for the old thread res
Jun 26, 2023 at 7:43 PM Post #119 of 119
Hey guys,

If anyone in socal (or even nor cal) happens to have an a-10 and wouldn't mind letting me demo it, please reach out! I'm willing to bring over any gear I have to let you try in exchange! Just trying to figure out if I the a-10 may fit my desires after the new b-21 blew my socks off at canjam (but I'm a tube guy at heart).

Also, sorry for the old thread res
If you find one make sure they have had the latest revisions. Revisions are no cost other than shipping to / from RSA and the last 2 have been major updates to the A-10 headphone output. Since my purchase, I believe there were 2 I believe.

I know one Head-Fier who purchased one used and sent it to Ray and he updated it and actually developed the latest revision while working on it. This Head-Fier uses it with his HE-90s and found it was an a great amplifier for it.
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