Parasound HCA-3500 Upgrades

OK, so I just bit the bullet on a Parasound HCA-3500 amp. These things are beasts! I am picking it up from the original owner and it looks brand new. Here is my question. I know about the R-44 resistor swap for the Holco 47k resistors, which eliminates the harshness on the top end, but I am considering a full upgrade of the capacitors and many of the other internal from Big Sky Audio.

http://bigskyaudiomt.com

They upgrade all the caps and such to High Grade/Audio Grade caps, and I am seriously considering the Rubycon Black Gate Caps.

Here is my dilemma, is the R-44 Resistor Swap enough? I have heard it gets rid of the edginess of the top end. Am I going to notice THAT much of a difference on an already awesome amp with the addition of the Big Sky upgrades?

Thanks in advance for your opinions!

Don

From my past experiences, sonic improvement is real when you upgrade the caps and some important resistors from the stock.

For about $100 or less in parts investment, I think it's well worth for the returns if you can DIY. Not too sure if the edginess is caused by one resistor you mentioned though but it's very possible.

I am willing to try an upgrade for this amp, and I have found a couple resources for suggested modifications...

Here is a list of what I have found so far:

1. Replace R44 with Holco resistors. I bought my Holco's before Holco changed the construction so use OLD Holco's or Resista's as John Curl says. Possibly also replace R28, R82, and R40 with old Holco's.

2. Replace diode bridges D8 and D16 with IR HFA08TB60 diodes or Fairchild Hyperfast.

3. Remove C25 – C32.

4. Remove C55-C60 and C49-C54 and replace with 0.1µF polystyrene RT RelCaps.

5. Remove C19/C20/C21 and C22/C23/C24 and replace with a 100µF/100V electrolytic and a 0.1µF polystyrene RT RelCap on each rail. I think Bob Crump mentioned the Nichicon KZ here.

6. Replace diode bridges D53 and D57 with Harris RURG3060 diodes. Remove all film caps from the power supply board.

7. Replace C11/C12 and C13/C16 with 100µF/25V BlackGate and 0.01µF polystyrene capacitors.

8. Replace R43, R46, R47, and R48 with Caddock MK-132 resistors of same value. Resistas would be fine here also. I am also looking at PMP resistors based on Michael Percy's recommendation.

9. Replace C62 and C9 with 10pF mica capacitors.

My problem is that I REALLY need a schematic of this amp. I have sent a request over to Tony at Parasound, but I am waiting to hear back. If someone has the schematic for the Parasound HCA-3500, I would greatly appreciate a copy :D

I am just trying to decide if the time it would take me to complete all this is really worth it, or just ship it off and have someone else do it :D

Thanks!

Don

Quote:

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Originally Posted by dcmartinpc

I am willing to try an upgrade for this amp, and I have found a couple resources for suggested modifications...

Here is a list of what I have found so far:

1. Replace R44 with Holco resistors. I bought my Holco's before Holco changed the construction so use OLD Holco's or Resista's as John Curl says. Possibly also replace R28, R82, and R40 with old Holco's.

2. Replace diode bridges D8 and D16 with IR HFA08TB60 diodes or Fairchild Hyperfast.

3. Remove C25 – C32.

4. Remove C55-C60 and C49-C54 and replace with 0.1µF polystyrene RT RelCaps.

5. Remove C19/C20/C21 and C22/C23/C24 and replace with a 100µF/100V electrolytic and a 0.1µF polystyrene RT RelCap on each rail. I think Bob Crump mentioned the Nichicon KZ here.

6. Replace diode bridges D53 and D57 with Harris RURG3060 diodes. Remove all film caps from the power supply board.

7. Replace C11/C12 and C13/C16 with 100µF/25V BlackGate and 0.01µF polystyrene capacitors.

8. Replace R43, R46, R47, and R48 with Caddock MK-132 resistors of same value. Resistas would be fine here also. I am also looking at PMP resistors based on Michael Percy's recommendation.

9. Replace C62 and C9 with 10pF mica capacitors.

My problem is that I REALLY need a schematic of this amp. I have sent a request over to Tony at Parasound, but I am waiting to hear back. If someone has the schematic for the Parasound HCA-3500, I would greatly appreciate a copy :D

I am just trying to decide if the time it would take me to complete all this is really worth it, or just ship it off and have someone else do it :D

Thanks!

Don

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Wow! Quite a long list there but not hard to DIY if you have experience with DIY before. I know John Curl is a n a l about resistors noise and hailed for the Holco and Resistas in the DIY audio. So, it may make the improvement about edginess.

I can attest to Nichicon KZ series caps being a good choice and makes a good difference.

I am pretty sure faster rectifier helps smooth things out a bit and bypass caps will also helps with better highs and mids.

In general, everything you said above are well documented mods and I believe they could improve your Parasound too.

So, go for it. If you can ship the amp safely and don't want to bang your head on a wall for a DIY mistake, ship it to the pro. Or if you want to get your hands dirty and got the tools, DIY is quite a satisfying route to go.

For me, DIY is not about money but brings a sense of satisfactions.

If you do DIY, take plenty of high resolution pictures before disassemble anything. It may comes in handy later. :D

Given the age of that amp, you may consider having the entire power supply rebuilt. My HCA-2200ii was in dire need of new caps in the low level signal section and that was about 3 years ago.

Pick your parts at that point.

I would not pay extra for BlackGates in a power supply. They are very nice for coupling caps (the N/NX series), but that's about it. Besides, they are discontinued, so the prices are through the roof now. Not sure if there are any signal coupling caps in the 3500 (they would require careful selection for best sound), but for normal filtering/bypass caps, I would just use a good low ESR 105C long life cap from Nichicon, Panasonic, or Elna. Talk to Tony at Parasound as well and see if he recommends replacing any of the regulator/transistors in the power supply as well. When I rebuilt my HCA2200, there were a hanful of small transistors in the power supply that he recommended replacing.

I am pretty sold on the Nichicon KZ caps. After speaking on the phone with Rick from Big Sky Audio and after more research, it seems the Black Gates are nice, but not THAT much better than the Nichicon KZ's. Through Rick at Big Sky, the Black Gates are a $199 upgrade on top of the regular upgrade cost. Seems like a lot... But I think that is based on their availability... Any inputs on that price?

I have done some DIY in the past, but getting together a parts list for this, and the BANG HEAD factor for me are quite high :D Should I not be so worried?

Thanks!

Don

Beware that the Nichicon KZ caps are only 85C rated and for 1000 hours. I would not use those in an amp power supply. Amps do get pretty hot and 1000 hours is not very much listening time.

It is usually best to select caps based on their specific use. Mix/match as needed for the best result. In the power supply, I'd use nothing less than a 10000 hour rated 105C caps (like the Nichicon HE or Panasonic EB).

Maybe use the audiophile caps on the signal boards in some of the critical spots, but not in the power supply.

Quote:

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Originally Posted by dcmartinpc

I am pretty sold on the Nichicon KZ caps. After speaking on the phone with Rick from Big Sky Audio and after more research, it seems the Black Gates are nice, but not THAT much better than the Nichicon KZ's. Through Rick at Big Sky, the Black Gates are a $199 upgrade on top of the regular upgrade cost. Seems like a lot... But I think that is based on their availability... Any inputs on that price?

I have done some DIY in the past, but getting together a parts list for this, and the BANG HEAD factor for me are quite high :D Should I not be so worried?

Thanks!

Don

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Consider this. Not all Black Gates are created equal. There is different Black Gate series and the standard Blackgate may be not a lot better than a standard bipolar ones from Nichicon or Os-con.

I have not compared Standard Blackgate with the Nichicon KZ but I don't think the difference will worth extra $199. So, just go with Nichicon.

And consider what BillBillW said, the Nichicon KZ caps are 85 degrees. But again, if you want good caps at a reasonable price, they cost reasonable and improvements are well noted.

The Black Gate Caps I am referring to are the VZ series. Apparently the best that were available.

Don

I see. If you don't mind to fork over extra $199, VZ may be a better cap. Many DIY guys have accepted at the best lytics at one time.

One thing I know about it is that Blackgate were affordable and good performer when they are readily available and comparable to higher $$ caps at that time.

But since the Blackgate are obsolete and the price has gone up a lot, I don't know if anyone should spend a lot of $$$ to get them. And the other thing is the shelf lives of the electrolytics capacitors.

I would just grab a new fresh batch of Nichicon than the old stock of Blackgate caps.

But again, everyone has different opinions on this.

Quote:

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Originally Posted by dcmartinpc

The Black Gate Caps I am referring to are the VZ series. Apparently the best that were available.

Don

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Quote:

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Originally Posted by megasat16

I see. If you don't mind to fork over extra $199, VZ may be a better cap. Many DIY guys have accepted at the best lytics at one time.

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I looked up Blackgate again and the correct series is VK which is higher performance than the standard series. But I think all Blackgate are 85C also.

Well.... After much research and thinking and research, and more thinking, second guessing, then thinking again, I have decided to go with the Black Gate VK's in much of the amp, and the RELCAP RT's in the power supply and a few other areas. We will be replacing many of the resistors with PRP and Vischay MIL spec resistors. I have had talks with Rick at Big Sky Audio, John Curl, and Rick and John Curl have talked. Basically, at this point, I have the "Ultimate" upgrade for the HCA-3500 that John Curl and Rick could come up with.

I will basically be turning it into the Amp that Bob Crump and John Curl modified after it came out. Much like the CTC BBQ. Pretty excited and I will post my results once I receive it. My guess is that it it 3 to 4 weeks out, but well worth the wait.

Don

Yeah, you'll still be a long way from the CTC BBQ but not a bad start.

Well why don't you just sell me your BBQ and I won't have to upgrade my 3500! :biggrin:

I know it is still a ways off of the BBQ, but about as close to the JC-1's or the BBQ I am going to get without dropping a LOT more coin! It will be MILES ahead of a stock 3500 and miles ahead of any other amp that would cost me the amount of $ I have invested in this amp. John Curl himself has been involved in this rebuild so I know I will be getting a top notch result. Just trying to honor the late Bob Crump by doing the modifications for the 3500 that he came up with while working with John to tweak things as we go. In the end, I will have an amplifier that will last me many years to come, and quite possibly might be the best amp I will ever own.

Don

Some how missed this thread ,cool stuff having Curl wielding the iron on it for you.

John designed the amplifier and topology, Carl laid the boards and Bob hand picked the components used. You'll have a real keeper after it's all done.

Yeah. John was making the recommendations that Bob Crump had put together for the production 3500. Bob upgraded several 3500's before he passed away a number of years ago and that is basically what I am having done short of a couple pieces that are no longer available. I am replacing those with new equivalents. I am pretty excited to be using the recommendations of such a group legends. I feel privileged. Hopefully, this will become a standard upgrade through Big Sky so we can get a few more of these 3500's closer to what John, Carl, and Bob collectively came up with.

Don

Quote:

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Originally Posted by dcmartinpc

Hopefully, this will become a standard upgrade through Big Sky so we can get a few more of these 3500's closer to what John, Carl, and Bob collectively came up with.

Don

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I'd love to hear your listening impressions. I'm using an HCA-2200ii now, and I've been in touch with Big Sky about their normal upgrade for that amp. I assume that much of what you learn/use for your 3500 upgrade could also be used for my 2200. Please keep us in the loop, and if you talk to John again, tell him he's made an audiophile outta me.:smile:

Quote:

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Originally Posted by falconcry72

I'd love to hear your listening impressions. I'm using an HCA-2200ii now, and I've been in touch with Big Sky about their normal upgrade for that amp. I assume that much of what you learn/use for your 3500 upgrade could also be used for my 2200. Please keep us in the loop, and if you talk to John again, tell him he's made an audiophile outta me.:smile:

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I actually have a HCA-2200II on its way to me now. Once I receive both, I am going to be doing some comparisons, and most likely upgrading the 2200II also.


Don

any updates?

Well.... It is still sitting at Big Sky Audio. The upgrade is completed, but the back panel was damaged in shipping. The guy who sent it to Big sky didn't package it very well and the rear panel got severely dented. He thought he could pound it out, but it was worse than we thought. Long story short, Parasound actually still has replacement panels in stock and they are shipping him one right now. Once that is back on, just have to run through a final burn in test and it will be on its way home! I should have it next week.

Don

jeez... well, at least they were able to fix it! Keep us posted.

I know this thread is a little old, but I wanted to make sure I posted info for anyone doing searches to MOD the HCA-3500. There have been several different sites stating which MOD's to perform on the 3500. To my dismay I "blindly" followed them, and made my 3500 sound like CRAP. I have spent hundreds of hours and over $920 in "high end" parts to make my 3500 sing. Soft, sweet and subtle (power has never been an issue). I have them pushing a pair of Wilson Watt Puppy v7, and always loved the amp, but everytime I really got into a song and started to "turn it up", the highs are just edgdy, they litrally hurt my ears. My mission was to fix that. First things first, do NOT listen to the idiots in this post and others on the web that recommend replacing a 1000uf cap with a .1uf cap. Under NO circumstances should you ever LOWER the capacitance value in this amplifier. You can replace (3) .1uf caps with a single .475 (which has wonderful results). There are also a couple spots on my 3500 where a resistor was called for, but never actually soldered on the board! Obviously we fixed those spots as well.
I dont have the schematic in front of me, but anyone thinking about MODing this amp I highly recommend it, it is an amazing amp well worth the $850amp + $920parts to upgrade, there is nothing on the market under $5000 that would touch this amp. Just keep in mind Curl knew what he was designing, the quality of the parts was the issue, not the electrical specifications.

Why would you add resistors that were not present when the amplifier came off the factory assemby line? To modify an amplifier without the schematic and knowledge of how the different circuits operate is just asking for trouble.

The quality of the parts is fine, and it is in most electronics and loudspeakers. It's only the tweakers and folks that want to dive deeper into the hobby that they become an issue.

The design of that amplifier is also fantastic out of the box, as in STOCK.

The best version of that amplifier to date, period, is the CTC BBQ. Which was a hand built hotrod of the HCA-3500 with custom bodywork. The stereo version of the later Parasound JC-1 monoblock. It was tweaked and built by the actual designer John Curl, custom board work was by Carl Thompson and each component was personally voiced and chosen by Bob Crump. There's only about 7-10 that exist from my knowledge.

There are other companies that have seen the potential in that amp and have offered modifications based on basic amplifier theory, not any special knowledge. All they do is replace the customary parts that you would in any amplifier since it's not rocket science.

Modding an amplifier is not something you should jump into with cold feet. Or because you think you know what you're doing since it looks easy based on your last xover upgrade. The above is a prime example of what not to do. If you can do this and have knowledge of what circuit design is being used, theory and layout, then have at it but this isn't a high school tech club project. A few of the companies out there, like Big Sky, have a better working knowledge of it than others from the feedback I've read and the end result that I've heard.

Dcmartinpc has one of those aforementioned roadsters and the work performed is top notch. Eventually he'll post some pics as I believe he promised a long time ago :biggrin:

OK, OK, OK!!! :) I never did post any pics did I?? Well... first off, I LOVE this amp. I think about as good as it gets short of the CTC BBQ, which if I ever have the chance to buy, I think I would JUMP on. I would FIND a way to pick it up. Anyways. Back to this amp! Big Sky Audio performed the upgrades for me. He was great to work with and his work was top notch! Everything is extremely clean and if you did not know what you were looking for, you would think it was all stock. He performed replacements, upgrades, and modifications. I do not know the details of all of them, but I know he makes extensive use of Vischay resistors, AudioCap, Nichicon Muse, and in my case, some NOS of Rubycon Black Gate VK caps. This amp sounds wonderful. It has everything my very special HCA-2200II has, but more of it. I can't say enough good things about it and I honestly can't think of a speaker load it couldn't handle. It gets HOT, but I am pretty sure I keep it running Pure Class A most of the time.

I can't wait to get my upgraded SRS 2 crossovers back from Ben to pair with this. I think it will be a match made in heaven! Anyways, here are the pics, I will have to post a more detailed listening eval later. Please ignore the kid mess and excuse the smudges, I haven't had time to do a good cleaning on my equipment lately.

Don

http://the-martins.smugmug.com/Elect.../IMG0924-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0923-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0926-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0927-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0929-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0925-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0931-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0930-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0934-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0933-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0936-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0939-L.jpg

http://the-martins.smugmug.com/Elect.../IMG0935-L.jpg

Keep in mind DC that the CTC BBQ eliminated, not replaced, about 85 parts in the original design that were deemed unnecessary to the signal path. I'm sure it's very good but it isn't close to a BBQ and the work wasn't done by legends :biggrin:

You most certainly have the best HCA-3500 that I've seen in my travels.

I know that Big Sky removed a bunch of stuff too. :biggrin: I just don't know exactly what! I do know that he personally spoke with John Curl about my modification to make sure I got the best performer that I could. That has to count for something, right? I still have John Curl's phone number I think somewhere!!!

I know it isn't a BBQ, hence the reason I would jump on one if I could! But I figure it is the closest I am going to get for much less than even half what a BBQ would cost, or even a pair of JC1's for that matter...

Don

Absolutely and I doubt he cares if you call him....really? lol.

Great pics, DC.

I run a 2200ii. What do you think would sound better, an upgraded 2200ii or a stock 3500?

Also, what's up with your unbalanced inputs being labeled balanced? Did they do that on all the 3500's???:eek::tongue: