Parasound HCA-3500, Am I Crazy?


Hello to all,
I recently borrowed a friends Parasound HCA-3500 power amp just for the heck of it. [I was always curious how this amp sounded].
I unhooked my Parasound Halo JC-1's and hooked up the Parasound HCA-3500 in its place.
Much to my shock, there were some things that the 3500 seemed to do better than the JC-1's in my system:
The HCA-3500 actually sounded more transparent, open, and more extended on top than the JC-1's! This was especially true at lower volume levels.
The HCA-3500 also seemed to have a deeper soundstage, and a blacker background.
The JC-1's seemed superior in most other regards, however.
The JC-1's sounded smoother, cleaner, had slightly more body, more detail, and better bass control than the 3500.
The 3500 did sound a touch etched and slightly grainy, but it sure sounded damn clear, open, and transparent!
How could this be?
Anyone else out there experienced this?
Break-in is not an issue. My JC-1's have close to 1,800 hours on them.
I am just puzzled folks, thats all.
audio_girl
audio_girl
Nealhood: I agree with your comments although i would add that power cords should still be designed to resist RFI and pass plenty of current in an unrestricted fashion. After all, any exposed wiring / cabling can act as an antenna, so you've got to take that into account too.

Using heavy gauge conductors with a cable geometry that is naturally RFI resistant also presents a low nominal impedance and low series resistance. This allows current to be delivered in both a timely fashion and in the quantity needed. It also reduces the EM field around the power cord, so it is not inductively coupled into other signal or power cabling from other nearby gear.

As a side note, i'm using a unit that is similar to the Topaz mentioned above, but it is much larger, sturdier and heavier as it was designed for commercial applications. I've never weighed it, but when it was shipped into me, the weight on the bill of lading was listed as 450 lbs plus 30 lbs additional for the skid & packing materials. The 7.5 KVA unit that Neal made mention of weighs in at appr 116 lbs, so that should give you some idea of what i'm talking about.

On that topic, the Topaz T100H-7500 seems a little light to me at that type of power rating, so that tells me that it is lacking in core size. As such, i would consider this to be more of a 3.5 - 4 KVA unit in my opinion. Even at that level of output, you are talking about 30+ amps of continuous current capacity. Unless one is running very high current draw amps with very low impedance & low sensitivity speakers in a very large room, this should be adequate for most systems.

For sake of comparison, my old 2.5 KVA transformers clock in at over 100 lbs apiece, but they are WAY overkill on core size. I have seen 5 KVA and 7.5 KVA transformers that used smaller cores. That's the reason that i bought several of these, as i never had to worry about core saturation.

To take that a step further and for a more common point of reference, the old Tice Power Block / Titan iso transformers were rated for 1.8 KVA ( 15 amps ) and they clock in at appr 42 lbs each. Now you know why people running big amps used to complain about the Tice's ( and other "small core" iso transformers ) "squashing the dynamics ans smearing the sound at high listening levels" i.e. the core of the iso may have been temporarily saturating, introducing distortions and limiting peak current capacity.

This is why Tice came up with the Titan, as it simply used an additional yet identical transformer in parallel with the one found in the Power Block. This meant that you now had 84 lbs of core for the rated 1.8 KVA rating, which is obviously much better / allows more headroom during normal operating conditions. This is why i've said that you should look for an iso that was rated for almost double the max current draw of your components i.e. you have no chance of the iso distorting or saturating and the AC line impedance remains very low.

Obviously, power cords DO effect the sound of most components, but that's only because the components are still being fed "grunge" from the AC line and lack the proper design to deal with it. By going to the source of the problem and filtering the AC to a very high point of purity before feeding it to the system, you no longer have to rely on the guesswork of what power cord will "filter out the junk" the best on each individual component i.e. "The Super Vaporizer works best on digital whereas the AC Magna-Charger works best on amps". The only thing that power cord has to do at this point is deliver the proper voltage & current without allowing additional "grunge" & RFI to sneak back into the system AFTER the primary filter.

The fact that many "audiophile grade" PLC's still make "aftermarket power cords" somewhat of a "necessity" in order to achieve optimal results should tell you that the PLC itself isn't up to the task at hand. This could be why most of the "audiophile grade" PLC's don't provide meaningful spec's i.e. they rely on the thick metal chassis, fancy faceplates and snake-oil marketing departments to sell their mega-dollar units for them. Sean
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I just read the old January 2000 Stereophile review of the Parasound HCA-3500 the other day.
Bob Crump was right...they did measure pretty high levels of 2nd harmonic distortion, especially into lower impedances. This was also obvious by looking at most of the measurement diagrams.
The reviewer, Robert Deutsch, also commented on a "slightly forward sound, with a bit more upper-midrange/treble grain. These characteristics showed up as a somewhat etched quality on voices, massed strings, and the upper harmonics of trumpets, making the sound ever so slightly fatiguing over time." This was in comparison to the Rotel RB-1090.
Interesting!
I've only seen the Rotel part of the review. I can't find the Parasound portion online. As far as the RB-1090 goes, I think it's pretty good for the cost.

Dre
Hello,
I am thinking about changing out the above mentioned International Rectifier Mosfets, mentioned above by Bob Crump, and replacing them with Harris or Fairchild Mosfets.
I could not find the part # that Mr. Crump mentioned.
Does anyone have this information and/or part number?
Also, could anyone tell me exactly where these Mosfets are located inside the amp?
Thanks.