Mods for a PS Audio HCA-2?

I recently purchased a HCA-2, and I like it so far. But I was wondering what improvements I would hear, if I were to consider modifications? Thanks, Sonny
I modded mine (silver wire in output stage, Black Gate caps). There is more clarity in the mid and high frequencies.
There's a gentleman that frequents both AA and Agon that has performed several different mods to his HCA-2. According to what he's stated, the amp responds very well to some basic mods. I'm sure he'll chime in once he sees this post. If not, i'll drop him an email and see if he can help you out. Sean
I changed the output wire to solid silver in Teflon and replaced the cheap caps in the signal path to Black Gates. The difference will be immediate, but you will not fully appreciate the Black Gates for several hundred hours. It is not an exaggeration to say it doesn't sound anything like the stock amp anymore.

Everything is better. Especially dynamics and clarity. If you have the front-end to produce the piano properly, just wait till you hear the piano through an HCA-2 with Black Gates. The sustain and harmonics go on forever if they are in the recording.

In its stock form the bass was excellent with the HCA-2, but is seems even faster and tighter after the mods and the bass is surely more nuanced.

One more easy mod. Take the bolt out of the big transformer. Makes things smoother. Subtle, but noticeable.

Paired with the right speakers this amp is a steal with these simple mods. My speakers are 8 Ohm, 6 Ohm nominal, so take my comments with a grain of salt in relation to the load my speakers present.

As Sean will tell you, JA at Stereophile was disappointed with the measured results of the HCA-2 with a "test" 4 Ohm load. However, it seems the majority of owners of this amp don't "hear" JA's concerns. Same for the new Carver digital amp. Apparently it also measures like crap, but sounds wonderful as well. I personally can't say whether the HCA-2 sounds bad with a difficult load or not, but anecdotal information from several owners who have posted their experience with 4 Ohm loads don't seem to support JA's concerns. Having said that, I have read contrary posts from a couple of owners who thought the HCA-2 did have some problem with bigger loads. (However, the remarks from one of these owners has to be put into context. He is never happy with any equipment for very long before he is on to the next flavor of the month.) The point is, trust your ears. If you like this amp with your current setup, you will love it after these simple mods. For less than $75 this amp will take a huge leap forward.

BTW, I just recently received an email from a guy who did a blind shoot-out with the Odyssey Stratos and the HCA-2. Both the owner of the Stratos and the owner of the HCA-2 agreed the HCA-2 was better. The ironic point is that the Stratos owner was convinced he was listening to his amp (the Stratos) until it was revealed the amp in play was the HCA-2. Apparently he was stunned his Stratos lost. The only area where both parties thought the Stratos had an edge was in "detail".

Change the incredibly cheap stock caps in the HCA-2 and the wiring to solid silver and I am certain the HCA-2 will *easily* walk away from the Stratos in "detail".

I highly recommend these mods. They are cheap, simple and reversible.
Fiddler, I saw some mod packages listed here starting at $600, and adding $60, or even another $120, for a possible $820 total. It's not that this amount is out of the question, but I've been toying with the idea of bi-amping, so double that amount and add another HCA-2, and it's getting a little steep for me! You mentioned $75!!! Did you do the mods yourself?
I also have power hungry 4 ohm speakers, but the amp drives them pretty well so far. The reason for possibly bi-amping, is to try to improve the mid-range of my system with some different drivers and an active crossover
If you or Sean can let me know who does the work, and how much, then we can go from there.
Calanctus, You did the work yourself?
Yes, I did the work myself. I am a relative newbie to DIY and these mods were very easy. The wiring change takes the most time, but I am very meticulous.

The wire, Teflon tubing and the four Black Gate caps totaled less than $75.

Reference Audio Mods did these mods and a few more for another HCA-2 owner for far less money than what you quoted. I think the quotes you received are out-of-line. But that's just my opinion. I suspect a competent technician can probably do all of these mods in 2 hours.

If you know how to solder, I would certainly change the caps myself. This change wrought the biggest improvement by far! I think it only took me about 45 minutes start-to-finish if I remember correctly.
Unlike Fiddler I am not meticulous (except in caring for my gear), and I have no free time, so I hired someone to do it (local electronics guy, lots of exp. with stereos). He took about 2 hours and billed me for time only (I bought the parts).
With my Marantz SA-14 playing the Mozart Piano Concertos on SACD, I'm hearing no sustain at all on piano key strikes... my stock HCA-2 adds too much warmth and obscures some of the detail. Also aggravating is how the higher notes drop big time in dB, they just don't stand out as they should.

Not entirely sure if this is due to the amp or source, since I replaced both (the SA-14 replaced a SONY DVP-S9000ES which sounded truer on piano). So would the amp mod help both the sustain and lack of dB, assuming the amp's at fault?? I really want to keep this amp for all its other considerable virtues. TIA!

I suspect it may be the Marantz. I have read nothing but great things about the SA-14, but let me state my case as to why I say it may be your CDP.

Is the HCA-2 perfect? Certainly not, but it can benefit greatly from some minor improvements. After modding my HCA-2 I am hearing things I have never heard before in my system. Is it the work of the HCA-2. Yes and no. I believe the HCA-2 truly is excellent with the two aforementioned simple mods: taking out the Monster output wiring and replacing it with the solid silver wiring in Teflon and especially replacing the four cheap caps in the signal path with Black Gates.

Having said that, I think I have to give a lot of credit to what is in front of the HCA-2, particularly my Audio Note DAC 1.2. I built this unit with Black Gates, Tantalum resistors, solid silver wiring, Audio Note Copper Caps, custom HMS internal IC and NOS tubes. Since that time I have added an Audio Note Trans 280 between the Canare BNC and the digital chip and that made a substantial difference. But most recently I have added Audio Note interstage transformers between the digital and analogue boards ($$). Wow! Did this mod make a tremendous difference! The weight of the music took a quantum leap. Insert your favorite audiophile superlatives here.

So what does my modded HCA-2 have to do with that. Well, I think the HCA-2 is so transparent that it is allowing me to hear all of the changes I have made in front of it without adding much of a signature itself. The clarity, detail, dynamics, etc. are terrific. Just two weeks ago I had two friends visiting from LA (one a concert pianist) and he said the piano sounded absolutely perfect on my system. (Of course the 160+ Cuban cigars that we smoked in 10 days between the three of us may have clouded his perspective.) Certainly part of the credit of what he heard has to go to the HCA-2. I am convinced that a few guys who have been dissatisfied with the HCA-2 simply have scapegoated the HCA-2 because of one three of things: synergy with the components in front of it or the speakers behind it, the amp wasn't fully broken in, (it took forever, 200-300 hours minimum and I am convinced it improved up to 500 hours) or they heard the amp with the stock power cord. But as soon as I say that, I have to remember that my HCA-2 does sound significantly better after $75 worth of premium parts than it did in it's stock form.

Overall, I have a modest system, but to my ears and to the ears of many others who have heard it, the general consensus is that it sounds damn close to live music. I have tried to get the most bang-for-my-buck and IMHO the HCA-2 is king-of-the-hill in that respect. It just seems to let the music flow.

For instance, I am still using a Nak CD Player 1 from the early 90's as a transport (their flagship at the time, but probably my weakest link.) But it sounds amazingly good with my system. I removed the captive pc and installed an IEC and a Virtual Dynamics power cord. I also installed a Canare BNC connector. From the Nak, the signal goes via an HMS Il Primo digital cable to my highly modded Audio Note DAC and out from there to my preamp via HMS Gran Finale IC's.

I have a Supratek Chardonnay preamp with all NOS tubes including WE 350B's. This is an amazing preamp, especially for the money. Just read the thread entitled "Preamp Deal of the Century" here on the 'Gon.

Once again the signal exits via HMS Gran Finale IC's to my modded HCA-2. From there it goes via DIY silver speaker cables (thanks to Bob Crump) to highly-modded Newform Research 645's.

I have two dedicated lines and Virtual Dynamic power cords on all of my components except my HCA-2 which has a PS Audio Lab II. As good as the VD cords are, the HCA-2 snapped into place with the Lab II. Much more coherent and clear than the VD cord. The HCA-2 was supposedly voiced with the Lab II so I guess synergy comes into play here.

I recently switched to DH Labs Ceramic cones under all of my components and the change was significant. I also added a Neuance shelf under my Nak with the DH cones. The Neuance shelf helped the clarity immensely from my Nak.

Everything makes a difference. So can I say for sure how much the HCA-2 is contributing to the end result. No, but I can certainly say it is doing a superlative job of conveying the music from what's in front of it.

So in the end, I think it would be worth your while to change the output wiring and the cheap signal caps and if the piano still doesn't have excellent decay with outstanding harmonics, then I would strongly suspect any and everything in front of it.

Sorry for being so verbose, but I don't think it is ever simple to describe the performance of a single component unless the reader has actually heard the component in question with the exact same associated equipment AND in the same room. I think generalizations can be made about components, but ask two different guys their opinion about the same piece of equipment and very often you get two very different responses. Just take a look at the many threads here and over at AA that begin with, "What is the best ... (amp, speakers, cables, etc.)", and it is amazing the number of different opinions that are offered. In every instance there are more opinions about "the best" that are different than are alike!

F1a, what preamp are you using? Have you tried inverting phase at the speaker wires yet? Might be amazed at what happens....
Thanks Warren!

L milton:
Currently using the SA-14 (NBS cord) to a Meitner Melior pre via a Totem Sinew I/C, with a cryoed Meitner I/C from the pre to the HCA-2 ($1000 Tekline cord). I'm running Camelot Black bi-wire to Sig 805s on good stands.

The SACD in question is one of the original SONY single-layer discs that may in fact have been recorded in opposite phase, so I'll try switching L and R tonight. Once I upgrade to the PCA-2 pre it'll be nice to do that with the press of a button!

I believe the disc itself is flawed, since other piano tracks I tried the next day sounded very fine. The HCA-2 really is a remarkable amp: massed violins have a beautiful sheen to them - may not be entirely accurate, but extremely musical. Piano is not quite perfect, so I'm anxious to try the Blackgates and silver output wiring...

That silver won't be too BRIGHT I hope??
I agree with Fiddler. The Marantz is probably on the noticeably warm and soft side i.e. thick and dull sounding. Working with interconnects and power cables may correct some of this, but short of modifying the Marantz, you may be stuck with that sound. Correcting one set of problems may lead to a more revealing system, which in turn could have you looking for other problems once they are made more apparent. Sean
I have to disagree about the mods offered by asi audio being too much and 75.00 worth of blackgates and cheaper wiring is not even close to what asi is doing.

The three ps caps alone that they change to Jensen [read...better than blackgates] would cost a diy'er well over 500.00 for caps alone if blackgates were used.

The jensen caps are around 50.00 each and are also a 4 pole design and no rookie diy'er should attempt to install these.
There are also custom made parts in this mod.

I am not saying Fiddlers mods are not a good thing, but rather that there is no comparison to what asi audio is offering.

Check out the wiring on the four pole Jensens in the pics at and you will see what I am talking about.
I am guessing at least 300.00 in parts and wire for the basic mod and more than two hours time.
Have you heard an asi-modded HCA-2? Just curious how Jensens compare to B-Gates and what the rest of the mod contributes... TIA
I have heard neither of the mentioned amp mods yet but it is not a matter of Blackgates vs Jensen as the Jensen 4 poles are used in the power supply and the other diy mod has just a couple of Bg caps in the signal path.

The jensen caps are well known to sound better than even Blackgates when used in the power supply but they are not diy drop ins and require a lot more time and effort to install than any two pole cap.

I have had Blackgates and Jensens in the power supply of two different sacd/cd players but have not done a direct comparison on the same player but I will be in a couple of weeks.
Most pro modders will tell you that the Jensen is the best for power supply applications and the Blackgates still remain # 1 for signal paths.

If your in no hurry, I plan on buying an hca 2 soon and will do the signal path Blackgates myself and will send the amp to Doug at Asi for the Jensen ps caps and the other ps upgrades.

But my point was , you can't compare putting 75.00 worth of caps and wire to custom power supply mods, signal path upgrades and custom made parts that total over 300.00 , not to mention a lot more time being involved as opposed to the diy work.

I have used the Audio Consulting wire for ic's that replaced my Acoustic Zen ic's that cost 5 times as much but Audio consulting wire is not cheap at 3.50 ft for a single 24 ga strand and you have to figure multiple strands for an amp plus that cotton sheathing is not cheap either.
Ears, I do know an HCA-2 owner who had the same mods done as the ASI mods with the only difference being Harris FREDS. He had the mods done in steps so he could compare the difference of each mod along the way.

He told me that he heard very little improvement with the Jensen caps, the rectifier change, etc.

He said changing the output wiring was a significant, but the Black Gate caps were the most dramatic change of all. Makes sense to me. And I suspect this is the case since they are directly in the signal path.

My point here is that most anything can make a difference, but to what degree and at what cost? The bang-for-the-buck with the Black Gates is exceptional IMHO.

I did receive an email from ASI informing me of all of their mods. The gentleman from ASI explained to me that each of their mods to the HCA-2 makes a significant difference, but I wouldn't expect him to say anything different. What's he going to say, "Some of the mods don't make a big difference, but ignore that fact because I make more money if I do all of them?"

Look, I'm sure ASI does a fine job and I am not trying to slam them at all. There are many other companies that offer all kinds of mods to equipment. And in the end the consumer is responsible for deciding to have the mods done or not. ASI is certainly not forcing anyone to have all of their mods done!

It's just my opinion that some of the mods probably aren't worth the money. That's just the way I see it.
Oh you just gotta love the forum concept - most educational...
OK, where do I get BGs cheap? (ie. inexpensive!)
F1a, In response to your above question about piano, I recently purchased a Consonance 2.2 CD player, and plugged it direct to the HCA-2. IMHO piano sounds really good. So your decision to change your source, is probably a good one.
Also, if you are going to mod your amp, let me know where and how much. I don't think I'm going to try doing it myself. Sonny
Fla, I purchased mine at Reference Audio Mods:

BG_N_100_50 BlackGate N 100uf 50V [16mm x 31mm] $12.95

This mod is easy. Just take the mounting screws out of the printed circuit board. You will also have to remove a couple of screws for the balanced inputs on the back of the amp if I remember correctly. No big deal.

Turn the board over. Desolder and take out the four stock caps, then re-solder the Black Gates in position. It is one of the easiest mods I have ever done.

Changing the output wiring is just as easy, but it is more time consuming.

Good luck and feel free to email me if you have any questions.

Found this thread late, so most everything has been covered by Fiddler. He and I have shared notes on mods to the HCA-2, and in fact, he turned me on to Reference Audio Mods which had the best prices for the cpacitors.

Just to emphasize what's already been said, I did the mod in three stages. First, the output wiring was changed from double runs of stock Monster cable to quadruple runs of Jena Labs cryo'd 18 gauge hook-up wire. The improvement was far more than I had any reason to expect it to be. I've posted on this previously, on both AG and AA, so I won't repeat again.

This just whet my appetite for more, and talking to Fiddler I decided to change the four caps in the signal path to the Black Gates he mentioned. After a long break-in period, the amp had been transformed. I now felt it deserved it's Stereophile recommended component status, whereas prior to that, I didn't really think it was in that league.

I probably would have been happy stopping at that level of upgrade, since that represented the biggest, and highest value improvement. But with the amp now so much more revealing, I could hear a few things I wanted to see if I could improve upon. I decided after talking with Kyle at Reference Audio Mods to finish what I'd started, and he suggested Jensen caps to replace the large power supply capacitors. These are supposed to be a better choice for this application than the BG's, and have the added bonus of being less expensive. Since I'd also heard of another guy having a diode bridge rebuilt, I decided to go all the way and have RAM do the same (Harris FREDS). Since these caps/FREDS had to be mounted off the PCB, I had RAM do the work for me (I found they were only about 40 miles away from my location in So. Cal.). I dropped off the amp and the work was completed in a very timely manner (later that week).

The result of the last round of upgrades was more subtle than before, but significant and worth the price. The benefit was the noise floor of the amp had been lowered, and macro dynamics were improved. The HCA-2 also now had a more analog sound, for lack of a better description, and was was really overachieving- to the point that I had to have my Wadia 301 modified (also by RAM) in order to fully enjoy the upgrade to the amp. The Wadia upgrade is another story, but it was perhaps even more incredible. I didn't realize Redbook could sound that good.

I should also mention that I swapped out the Jena Labs wire for the Audio Consulting silver wire that RAM sells. Both sounded great, but the silver is now soldered in place, so I'm selling the Jena labs wire on AG in the next few days. I just want to put the disclaimer out there so that nobody thinks I'm hawking my Jena Lab wire when they see the ad in a couple of days. Both are good, and I'm sure others are too. The main point is this amp has a lot of potential beyond stock.

The bottom line is the basic design of the HCA-2 is great, just remove the most limiting price point components and you can move to a level of performance usually costing a multiple of what you've invested. It's a high-value way to get a high-end sound.
Wehamilton, What you had done, sounds alot like the mod package that's being advertised here on Audiogon. What was the entire cost, if you don't mind. I'm across the country, in Ct. I'd like to find someone closer.
Also, I thought that Fiddler said that the additional mods didn't result in that much difference in sound?
Total parts cost for the three levels of mods came to $500. That included quadruple runs of the Audio Consulting silver wire and cotton sleeves, four Black Gate caps in the signal path, five Jensen caps in the power supply, along with four Harris FRED diodes. Two other Black Gate caps (1000 uf) were also installed when the power supply was upgraded, but I don't know their function. The price also included a couple feet of silver hook-up wire to install the four pole Jensen caps.

You should re-read my post above, because I think the upgrade to the power supply was very significant- just not as much bang for the buck as the first two upgrades, which were relatively inexpensive. The upgrade to the power supply improved macro dynamics, lowered the noise floor, and also made the amp more natural sounding. Since I also upgraded the diodes and the two other BG caps at the same time, I can't precisely say what change resulted in what sonic improvement, only that the end result was worth the money spent.

I should also mention that I'm powering the HCA-2 with a P500 using the Multiwave I setting, and I'm using PS Audio Statement power cords. I mention this only because this amp MUST have good power going into it. To get the same results I got, you've got to feed this amp clean power. I find the new Multiwave makes a big differnce, with MWI giving this amp huge air and a sense of space to the music (oddly enough, my TV much prefers MW II).

So that was also part of the reason I upgraded the HCA-2 power supply- I was already aware of the way this amp responds to improvement to the power going into it. I figured without taking the final step, I'd never get the full potential this amp is capable of delivering. I think my educated hunch was correct based on the results.

And as a final thought, someone in the above thread mentioned how the Jensen caps are preferred in the power supply application over the Black Gates (which are better in the signal path). This is the same advice I got from the guys at Reference Audio Mods, so don't think just because the BG's are more expensive that they are always better.
One more thing I should mention. Paul Mc Gowan was asked on the PS Audio discussion forum about the difference between the HCA-2 and the Classic 250. He said that the HCA-2 does some things better than the Classic- I think he said faster transients, and more linear response among other things, but that it could never have the "weight" of the Classic 250.

I remember that comment because the mods I made to the HCA-2, really improved the "weight," making almost everything from piano, drums or the full orchestra have a power and realism that just wasn't there before. I can now listen to a piano, and the left hand notes are now room-filling, big, round powerful notes. Kick drums shake the room, but in a very realistic way, not just a big sloppy thump. And when an orchestra gets going, it makes the hair stand up on you neck- just the way it's supposed to.

One other minor tweak I forgot to mention in the previous post was removing the mounting bolt that runs through the center line of the torroidal transformer. This simple mod gives a more open and airy sound. But you absolutely must use extreme caution when moving the amp around, because if that transformer gets lose, it will do some serious damage!

So to conclude, I think at $1695, the HCA-2 is a great amp for the money. But add the $500 of mods, and now it's just a great amp- period.
I was intrigued to come across these comments about the improvements the mods make, because they sound like what I might be looking for. I've owned an HCA-2 for a few months now, and while I don't regret the purchase -- I'd find it hard to go back to a conventional solid-state amp now -- I've been bothered a lack of body and texture in the mid-range and upper bass. Sort of a thinness or hollowness.

Using a PS Audio Statement interconnect between the pre-amp (Marsh p2000) and amp somehow seemed to help to fill in the texture a little, but I'm still looking for more. I'd appreciate any further thoughts on what I might try next. Have other HCA-2 owners found the mods to solve the kind of problem I'm having? Or should I try other things first, like a different power cord (right now I'm using a LAT)? For the record, the rest of my system comprises an Arcam CD92 and Thiel 2.3 speakers, with Acoustic Zen Matrix Ref IIs between the CD player and preamp, Acoustic Zen Satori speaker cables, and a PS Audio Ultimate Outlet to the CD player.

Thanks for any tips.
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
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
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.
Naunc, John Zurek from Positive-Feedback auditioned the HCA-2 paired with Thiel 3.6s and found them to be a good match.

In fact he is now using the HCA-2 as his main amp.

As for Sean's comments, I and many others couldn't give a rat's tail whether the HCA-2 deserves a Class A rating or not (it has already been debated to death in this and other forums). If we were to all buy every "Class A" rating product we might as well be born with bar codes imprinted on our foreheads. Do you always judge everything by a rating? You shouldn't because it is your ears that is the ultimate judge. So if a professional reviewer uses this amp with a pair of power hungry speakers like the Thiel 3.6, does that mean his hearing is poor and he could not discern at all that the amp "was neither fast enough nor stable enough for me to consider it a worthy product." Obviously he found something he liked and so did I. I am currently using the HCA-2 to power a pair of Martin Logan Aerius i's which are well-known in audiophile circles to be voltage vampires. They make a good synergy as Fiddler would say. I have even hooked this up to my dad's Maggies 1.6s with stunning results. Lack of speed; not reliable- are you kidding me?

If the HCA-2 is lacking for Naunc, then perhaps he may have to re-evaluate his system set-up (speaker placement, room acoustics etc). By just removing the bolt from the transformer of the amp (a worthwhile tweak I read from others), the sound became much better. Tweaking is worth it for this amp. I mean for $1,695 how you can lose? You can buy a used one for a grand or less- tell me how many amps out there at that price can give such a high-end performance. Besides I have seen this amp drive difficult speakers with no problem at all and so contrary to Sean's opinion there are many others out there who feel that this amp has enough power.


Fiddler: Fast amplifiers have wide bandwidth, they don't ring just above the audio passband, they reproduce square waves easily, etc... This amplifier fails all of those tests as can be seen in the Stereophile test results of the HCA-2.

Having said that, a lot of people are fooled / confused into thinking that the system is "faster" by reducing the amount of sound that they hear. Less density to the sound, in tonal balance and / or harmonic structure, tend to make things sound cleaner and clearer i.e. add apparent speed due to the sound being less congested. Evidently, a lot of people that own or have heard the HCA-2 that think that the amp is "fast" don't know what they are listening to or for. What do i base this statement on? The Stereophile test results proved this amp to be "slow" beyond a reasonable doubt.

One can buy, use, listen to whatever they like. That is obviously everyone's individual option open to their own preferences. I'm not debating that some people will like how this amp sounds / interacts with specific components. The fact that this is a poorly designed amp, lacks speed, lacks stability, etc... has already been verified and is not really open to debate. At least not by anyone that understands how electronics work and can interpret test results. Sean
Sean, it appears that you are still obsessed with Stereophile ratings and tests. Although I would not go to the extent of calling this amp "fast", I cannot say that it is slow or lacks speed either. The Stereophile tests indicates "a lack of high-frequency linearity" but this is not all that uncommon for many amps. The main thing is that it does provide enough power to drive a large variety of speakers (not all- hence the qualification). To call it a "poorly designed amp" is a ludicrous and amatuerish statement. After all, if it was poorly designed, it wouldn't be able to drive my Aerius i's, Maggies 1.6. Thiels or countless other speakers even at high volumes. If it was poorly-designed it would break down easily, and the music would sound no better than being driven by a $100 receiver from Circuit City. If it was poorly designed, the whole technology of Class D and digital amplification is nothing but a scam and that companies such as Spectral, Bel Canto and others should just pack up their bags and throw away their digital amp models.

Why is it not open to debate? There are no hard fast rules to high-end audio. Anyone who "understands how electronics work and can interpret test results" also realize that the ears are the most important judges of sound. If it doesn't sound musical or good, then it doesn't matter what kind of specs are out there. It seems that you rely too much on specs and this is something you have to learn not to get caught up in. Specs are good- they tell us a certain level of performance that the electronics is expected to have but do not always indicate how the music will sound to "your" ears!

Here is a quote I have taken from Robert Harley's "Guide to High-End Audio":

"Many newcomers to high-performance music reproduction- and even a small fringe group of experienced audiophiles- question the need for listening to evaluate products. They believe that measurements can tell them everything they need to know about a product's performance. And since these measurements are purely "objective," why interject human subjectivity through critical listening?

The answer is that the common measurements in use today were created decades ago as design tools, not as descriptors of sound quality. The test data generated by a typical mix of auio measurements were never meant to be a representation of musical reality, only a rough guide when designing. For example, an amplifier circuit that had 1% harmonic distortion was probably better than one with 10% harmonic distortion. It doesn't follow that a harmonic distortion specification in any way describes the sound of that amplifier.

A second problem is that audio test-bench measurements attempt to quantify a variety of two-dimensional phenomena: how much distortion the product introduces, its frequency response, noise level, and other factors. Music listening is a three-dimensional experience that is much more complex than any set of numbers can hope to quantify. How can you reduce to a series of mathematical symbols the ability of one power amplifier, and not another, to make the hair on your arms stand up? Or the feeling that a vocalist is singing directly to you?

.....No matter how many measurements are gathered about the product's technical performance, they still don't tell you how well that product communicates the music. If I had to choose between two unknown CD players as my main source of music for the next five years, I'd rather have ten minutes with each player in the listening room than ten hours with each in the test lab. Today's measurements are crude tools that are inferior to the most powerful test instrument ever devised: the human brain" (Harley:p 34)

What is important to you- specs or the music? Are you an equipment lover or a music lover? Do you hear music or do you hear music as judged constantly on the performance of specs and latest technology. If it sounds good, it sounds good. Many tube amps have very poor ratings in terms of tech specs, but sound extremely good. Remember my friend, music like Harley points out is a three-dimensional experience.

The HCA-2 amp is not a flawed amp because it can successfully drive a number of speakers and the many owners of this amp are extremely happy with the result (the money-back guarantee by PS Audio is further proof that the company stands firmly behind its product and is not going anywhere anytime soon).

I read a lot of magazines and run audiophile forum, but at the end of the day, I trust my ears only. I have had my HCA-2 for 15 months now and not once was it broken or failed in any of my listening experience. I play this amp at least 4 hours continuous every day and it has never let me down- a flawed amp like you suggested will not be able to perform to not only my expectations but many others as well.

So give it up with the test results, the "square waves" etc (yes they are useful but do not give the final judgement on how the amp will sound) and just enjoy what you have without trying to put down a product based on specs. Using your own words: "I'm not debating that some people will like how this amp sounds / interacts with specific components" there shouldn't be any problems- am I not correct? No amp is perfect out there but hedck, if like you said, people like the sound of this amp then how can it possibly be "poorly designed"?

Remember as well, understanding "how electronics work" as you stated is not the same as understanding music and how music affects you. Before you start brandishing your comments on informing readers/contributors of this forum about the apparent flaws of this amp, try to gain a better perspective on the main thing that counts- learning to enjoy music and forgetting about the equipment. It is often the hardest thing for many audiophiles to overcome and is the greatest test they must pass. Trying not to change equipment every two months (controlling upgraditus) and listening with enjoyment is the real way to audio nirvana. Fiddler has the opportunity to buy an amp far costlier but still sticks to this- why? Because it gives him the greatest amount of enjoyment. Isn't that what high-end audio is about?

Cheers and happy listening!

I can spend a half an hour picking this amp apart in terms of why it is poorly designed and add links to where people found it to change sonics into different loudspeaker loads due to poor stability, but i'll just say "buy and use what you like". Sean
Sean, you said recently you have 20 amps, which I don't doubt. I would be very curious to hear what the top five are that you own.
Actually, Sean, it will only take a couple of minutes more to list all 20 amps that you have purchased or acquired on the basis of their performance.
I'm currently having another round of mods performed by Reference Audio Mods on my HCA-2 and will report back soon if possible. I've moved into smaller quarters and my listening room is so compromised I'm not sure I can make valid observations, but I'll report anything that I can on this subject.

It's been a while since I spoke with Kyle, who is doing the work at RAM, but I believe he's upgrading the digital power supply and some of the other more cost-effective mods that are remaining (I've done the easy ones already).

I just happened to stop by and was surprised to see this thread was still going. In reading the recent comments, I can find some truth in most of them. Certainly the stock components are far from optimial, and they are such an impediment to getting the most out of this amp that I can't comment on Sean's comments relating to inherent design deficiencies. They may in fact be there, but with so many other things getting in the way first, I don't feel like I've eliminated enough varialbes to say now I can evaluate the design. I'm hoping any design shortcomings will be more apparent when everything else has been upgraded. Until that time, the cheap caps, ringing power supply etc, make it hard to evaluate what's really inherent in the design itself. Of course, some of that is the design, so I'm not pretending it isn't.

I've posted a lot about this in the past but will say again- in stock trim, it's a heck of a deal at the price. However, IMHO, there's no way it's a Class A product stock (for those of you that care about those ratings, and even for those that don't). The important thing is that the mods I've made have resulted in such an overall improvement that I now thoroughly enjoy listneing to it, and as a result, don't spend much time anymore thinking about whether it's a Class A or not.

I'll report back anything I can when I pick up the HCA-2 with the latest upgrades.
Hi Guys,

I've never posted on audiogon but here goes. Firstly, sorry for digging up this old thread but i have recently purchased a demo model hca - 2 and imported to oz from the states.

I have read this thread from entirety and find it really interesting. I'm sure Fiddler was one of the people i contacted regarding mods to this amplifier, i've had so much advice i can't remember everybody's moniker.

Anyway, i was a bit disappointed with the sound of the stock amplifier to be perfectly honest. I have an aksa 100 nirvana plus amplifier and i thought the ps audio hca - 2 was better in some areas. However, where i was disappointed was the lack of inner detail/timbre, lack of dynamics and bass. The amp just didn't grab my attention and i thought it was boring.

After researching modifications i decided to have a tech friend install the 4 blackgate 100 uf 50 volt non polar caps in the signal path for me. They replace the cheap xicon 100 uf 35 volt caps which come stock with the amp.

Anyway i have about 20 hours on this amplifier and AFAIK it is a keeper. The dynamics are much better, the bass has improved (i'm satisfied with it) and importantly the inner clues/emotion of the amplifier is excellent. I had a really good time listening to the amp last night.

My tech friend did have a problem whilst installing the caps as the track lifted and he had to use a bypass wire to repair the damage. I guess what i'm saying is this mod isn't for a beginner.

My system is as follows:

marantz cd4000 (stock and cheap)
perpetual technologies p3a (modwright level 2)
N.e.w. p3 preamp (modified)
ps audio hca - 2 and aksa 100 nirvana plus
War audio speakers (raven 1 tweeter, mtm design, 2 x 7inch focal kevlar midbass drivers)
bluenote piccolo turntable
bugle phonostage.
bolder cables.

Best wishes