RSA A-10 and BHSE

look through the canjam thread. if not there, then have to wait, as A10 is not out yet and few have the BHSE.

It was really difficult to get a seat to listen to the A10 at CanJam as it always seemed to be occupied, and same with the BHSE. Also, the amps were in completely different rooms and using different sources, so any real kind of comparison would be silly. I did manage to get a brief couple minutes with the A10, and liked it well enough with HE90s and HE60s. I'm not a big fan of the Jades, which I've heard on 4-5 occasions now, so saying I wasn't impressed with them this time only confirms my opinion of those headphones (I also don't dislike them; just not for me). I really fell in love the BHSE with the O2 at last year's CanJam, and have heard it a few times since, at meets and in more private settings (hotel room, member's home), so I'm more familiar with it, and liked it enough to sell off most of my gear to buy one. I don't think anyone has had enough time with either to begin a comparison, and unless a really crazy head-fier with deep pockets is going to buy both, or both are at meet where some kind of shoot out can be arranged (same source, headphones, etc), it's going to be very difficult in the near future to get a good comparison going.

it seems that the A10 is voiced for the HE90 and the BHSE for the O2. i'm sure both amps will drive both headphones, but that is something to consider.

A10 is voiced for the HE90? interesting..

Stating that the BHSE has been voiced for the SR-007 (or any headphone) is simply not true. It is a fully DC-coupled amp so the aim of the amp is to be as transparent as possible, wire with gain if you like. The fact that it mates well with the Omega phones (the SR-Omega and SR-007 Mk2/A are also excellent matches) is no magic but these are simply the most demanding loads for any amp to drive and will show off a highly transparent system far better then the HE90. The BH circuit is meant to step out of the way and simply allow the phones to shine while providing ample voltage and current for them. That's why the BH also makes the ESP950, HE60, Stax Sigma's or any other headphone that I tried with mine shine.

The only exception was the HE90 (and probably the Jade but I didn't have a BH here to try with them) since have a very specific amplifier needs which are less about the amps technical ability but rather how it has been voiced. You only need to study the HEV90 to see proof of that as Sennheiser "crippled" the sound of the amp by using polyester coupling capacitors. Mikhail did something similar in the ES-1 (and ES-2 amps) though he had his customers pay for very expensive caps (400$ each) and then serial connected a 1$ cap for that magic tuning. You don't have to be an EE to see how wrong that is.

I must say, perceived sound aside, I can't see why you are comparing the BHSE to the A-10. The new Woo Amp is a much closer match to the BHSE with much more power on tap and an output stage that can handle the wild impedance swings better. You only have to look at the figures for the amps to see why. The BHSE swings 1500v P-P (stator to stator) and the Woo WES will be 800-900v P-P (depending on how they finalize the design). Edit: I've been told that the WES should reach the full 1500v P-P output swing in the production version, same as the ES-1 had.

Spritzer,

Couple of things in your post really piqued my interest.
- Please could you elaborate on the 'voicing' issue with the HE 90s? Is it possible to 'voice' an amp to drive them well without compromising sound quality? Any examples?
- Any idea how the Rudistor circuit designs (e.g. Egmont, Coriolan 2) compare with the WES and the BHSE? Rudi claims 1300 Vpp for the Coriolan. Have you heard either of them or had the opportunity to analyze the circuit topology?

I am considering getting a new electrostat amp to try to get the most out of my HE 60s and HE 90s but getting to hear the main contenders is hard enough, let alone comparing them side-by-side.

Many thanks.

If you are voicing an amp then you are altering the basic sound signature and thus, in ultimate terms, sacrificing a bit of fidelity i.e. the end result isn't as true to the source as it could be. Now this is often justifiable to play on the strengths of some transducer while toning down what weaknesses there are. That's exactly what Sennheiser did with the HEV90 and Justin did with the Aristaeus. If you like the sound signature of the phones then this would be the best move IMO. One caveat though, the HE60 needs a rather different amp then the HE90. The smaller brother simply loved the Blue Hawaii and came alive so to speak.

I am listening to my own version of the circuit which Rudi uses now. It has a much better PSU then his amps and the tubes are rather different since I don't find the 6SN7 to be a good choice as an output tube. I used ECC99's as drivers with 6S4A's (same as the ones in the Woo GES) as output tubes and the end result is quite good. I must say though that I initially built the amp according to the basic design but was far from happy with the end result. I then tweaked some values plus I added negative feedback to the amp and it is quite a bit better to my ears now. Even with the upgraded tubes, higher PSU voltages then I'd only rate the amp on par with the Stax T1 amps. They are cheap to build though so if you want a simple DIY project I do recommend building one.

As for the P-P value, there is more then one way to measure this and Rudi has been known in the past to pad his numbers. He has even quoted S/N ratios which would only be possible if the amp was permanently submerged in liquid nitrogen.

Thanks Spritzer!

So based on your knowledge of the circuits and listening experience, would any of the current crop of currently available high-end electrostatic amps (BHSE, Woo WES, Coriolan 2, A10, etc.) offer better fidelity with the HE 90s than the HEV 90, or are the advantages of the better circuits, components, etc. rendered moot by the incorrect voicing?

Two small children leave me with precious little time for listening, let alone a home-build, and I don't rate my chance of tracking down an Aristaeus in the near future...

Justin may still be able to build you an Aristaeus.He still had boards the last time I talked to him,so give him a call.This really is the best amp I've heard with the HE90's,but I haven't heard any of the newest crop except for the BHSE.Gary

I'm also very interested in a electrostatic amp that offers better fidelity with HE90 than the HEV90.

The HEV90 certainly can be improved upon and that's just what the Aristaeus is, the same basic idea only upgraded. I'd say this would be your best bet and Justin has said that he's going to build a few more. Given his workload, it could take a while but you better talk to him about it.

The Woo WES might also be a good match but I don't think anybody has heard the final version yet.