Mods for a PS Audio HCA-2?

The thing that folks need to understand about stock components is that they may have great frequency response with a steady-state signal, but they usually have dissapointing transient response. Mods are the only way to fix this. Power delivery to the active devices is the problem. The capacitor types and locations, the wiring topology and wire types make a huge difference here. A typical sotck amp may have great bass response and reasonable mid-band transient response, but lousy high-frequency transient response. Unless the transient resopnse is UNIFORM at all frequencies, the music will not sound live.

Steve N.
Empirical Audio
Manufacturer
http://www.empiricalaudio.com

Naunc, I have never heard your speakers so I am speaking totally out of school here, but what I have read on this board and others is that what you are hearing, many others have iterated about Thiels.

Before I get any Thiel owners upset, I am not saying they are not great speakers, but I think it comes down to one's preferences when listening to Thiels as with many other speakers.

I don't have the issues you describe with my HCA-2, but in fairness, I have done some mods to my amp that did greatly improve the amp. Unfortunately, it has been so long since I heard my amp stock that my lack of aural memory doesn't allow me to specifically address the stock sound of the HCA-2.

Well, yes, the Thiels are certainly what I would call a cool sounding speaker but I did hear more body and warmth from them with other amps I auditioned. It's just that the HCA-2 was so good in other respects, and especially in avoiding the hardness and greyness of other solid state amps. I'm hoping that the things I'm not so happy about with the HCA-2 are not due to anything intrinsic in the design but can be tweaked away somehow.

Audioengr: You can't fix what isn't there. That is, unless you re-design the circuit. If you do that, it is no longer the same product.

Other than that, there's a reason that i've always stressed wide bandwidth. In order to achieve wide bandwidth, you have to have speed. With speed, linear dynamics are an afterthought and everything falls into place a lot easier. If you can maintain this speed into any given impedance, you've now got stability. Stability results in consistent results & performance regardless of the load. Therefore speed and stability are the key factors here, nothing else.

This is why i "bagged" on the HCA-2 so much. It was neither fast enough nor stable enough for me to consider it a worthy product. The fact that certain folks at Stereophile recommended it so highly ( ST ) that JA overlooked the poor performance and ranked it in Class A recommendations are what made me stir up all the hoopla about this amp. All i can say is that in stock form, this amp would be nothing to write home about. It may be miles better after being modified, but those mods would have to be pretty adventurous to bring it up to what i would consider a "Class A" type of component. Obviously, these are just my thoughts which are likely to clash with other personal points of view. Sean
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Sean, interesting comments.

Never heard one owner, even those who have sold their HCA-2 complain about it not being fast enough. Just the opposite. Universally, it seems that everyone has been impressed with the incredible speed of the amp.

And once again you refer to the Stereophile measurements. The stability issues came under what load. Many amps would be worse. Mate the HCA-2 with the right speakers (as with any amp) and the stability issues aren't a concern. As with any component, they all have their limitations. I just recently listened to several highly regarded amps that were multiple times the cost of the HCA-2 and I wouldn't have traded even-steven for any of them. The HCA-2 simply did so many things better. But then again, I understand the limitations of the amp and I am not trying to drive Apogees with it either. If I were, it would be out the door in a heartbeat.
As always, synergy is incredibly important.