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Improve the Sound of your Parasound HCA3500

How many of you out there have checked the AC Polarity on your Parasound HCA-3500 power amplifier? There is a 70% chance its reversed!Mine was also.You can improve the bass, imaging and coherency by changing it around.
Another way to improve the sound is to change the main feedback resistors [r-44 on the circuit board].Remove the Vishay 47K resistors and replace them with Holco 47K resistors.You can obtain the Holcos at Michael Percy Audio.The main feedback resistors are located near the back of the unit and alittle over half-way up on the side circuit boards.There is one on the right circuit board, and one on the left.Again, numbered R-44.This eliminates the grain and edge in the highs and the unit sounds more open.Both these mods together make a big improvement in the sound! I got this idea form John Curl and Bob Crumps posts on audioasylum.com.Try them, they definitely work!
daltonlanny
socrates
247 posts
 
Do these tweaks work for the HCA2200mkII as well?
daltonlanny OP
301 posts
 
Socrates,
Ask Bob Crump this question.I have no idea, myself.Thanks.
rcrump
427 posts
 
Never been inside a HCA2200 .....Might be a good idea to check the AC polarity as it is with any piece of gear inserted into your system......
sean
6,231 posts
 
Other than AC polarity, most all gear responds quite noticeably to swapping better quality parts for lower quality parts. Sean
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daltonlanny OP
301 posts
 
Hello all,
Sorry to resurrect such an old thread, but I cannot contain my enthusiasm for the Parasound HCA-3500.
I owned one in the past and sold it, but decided to buy another used one a few weeks back.
Out of the box it was sort of harsh, forward, etched, and grainy. I thought BIG MISTAKE!
But,
Five EASY and CHEAP things that I have done have dramatically improved my HCA-3500:

1. Using a Parasound P/LD-2000 preamp. [Theres a synergy there, after the mods are done].
2. Installed dedicated outlets with 20 amp breakers, one for each channel, on the amp. My other equipment goes into seperate outlets from these.
3. Changed out the R-44 resistors, [one on each side of the amp], from the stock Vishay 47K to Holco 47K. I got the Holco's at Michael Percy Audio.
4. The AC polarity on my HCA-3500 was reversed, just like the first one I owned, so I changed the wires around in my dedicated outlets.
5. Floated the earth grounds on both channels of the amps.
[The preamp is still connected to an earth ground]

Floating the earth grounds on both channels of the amp was the final thing I tried, and turned out to be the icing on the cake! After I floated the grounds, the sound became quite a bit cleaner, with much less grain and hash, a wider soundstage, and a more relaxed and somewhat more laidback sound, which is a plus with this amp.
Now the harshness, etch, and grain is almost completely gone, and I like the 3500 better than the JC-1's that I did own. The modded HCA-3500 is more lively, clear, dynamic, and has better treble dynamics, and depth than the JC-1's.
The JC-1's sound slightly muddy and vague in the mids and highs, and less dynamic in the highs, compared to my HCA-3500 believe it or not.
My HCA-3500 now has crystalline clarity, transparency, tons of detail, depth, a wide soundstage, and punchy dynamics
I am now going to experiment with aftermarket power cords.
Wow, what an improvement!
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