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Parasound HCA-3500 Modifications / Upgrades
Parasound HCA-3500 Modifications / Upgrades
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Old 25th October 2010, 02:55 PM   #1
dcmartinpc is offline dcmartinpc
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Default Parasound HCA-3500 Modifications / 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 checking the AC Polarity and 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 internals from Big Sky Audio.


They replace resistors in the input, biasing, and feedback circuits along with replacing all the inexpensive generic capacitors installed by the factory with audio grade types. I am seriously considering the Rubycon Black Gate Caps at an additional Cost. Typically they use the Nichicon Muse KZ. Are the Rubycon's worth it?

Here is my dilemma, are the AC Polarity check and the R-44 Resistor Swap enough? I have heard it gets rid of the edginess of the top end. These I know I can do myself. 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!

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Old 25th October 2010, 06:36 PM   #2
john curl is offline john curl  United States
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I think it is a good thing to do the upgrade. I don't know these people, but my associates and I found that these upgrades are needed to make the amp sound its best. In fact, the 3500 can made into a $5000 amp with enough upgrades. The next biggest improvements should come from using 200V Rel RT polystyrene bypass caps (Michael Percy), and high speed, high voltage and sometimes high current diodes, instead of the diode bridge(s). This is a big step and maybe not worth it. Black Gate is OK, but electrolytic caps are not directly in the signal path, and BG is very costly. Nichicon Muse works about as well.
"Condemnation without Examination is Prejudice"
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Old 25th October 2010, 08:52 PM   #3
dcmartinpc is offline dcmartinpc
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Join Date: Sep 2010
Thank you John for replying!!! I was thinking about doing this myself, but the more I look into it, the more I am afraid of the "Bang Head Here" factor Is there a company you are aware of that does the upgrades to these amplifiers that you recommend? If you do, I would be VERY appreciative of the recommendation. I want to make sure I get the correct upgrades with the correct components.

I did some more research, and it appears that the Nichicon Muse KZ Caps are going to suit my needs. The Black Gate VZ's are nice, but a costly upgrade.

Thank you again for your reply! I look forward to your and everyone else's comments! I want this amp to absolutely SING.

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Old 27th April 2015, 03:43 PM   #4
seakinggr is offline seakinggr
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Hi to all, I have some questions, I just bought a 3500, first where can I find holco 47K resistor, second how do you check the AC polarity in order to change it, and third I was looking the big side boards and I noticed that R135 have 2 resistors one on top of the other, any idea about this? How can I find a schematic for 3500.
Thank you all in advance.
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