Pimp my Pioneer A-509?

[question82]

Hi.

Recently I got the service manual for my Pioneer A-509R.

I found out that its power amp consists of the IRF9540 + IRF540 MOSFETs by Fairchild.

I googled and searched the web to get more information about these parts.

So I've found the following Thread posted in this forum:

alternative mosfets for Zen amp

Does this mean that I would probably have better sound if I replaced the IRF9540 by Fairchild's IRFP9140/240, and the IRF540 with the IRFP140 ??



Could I simply replace the four MOSFETS, without having to exchange or reconfigure other parts of the Amp because:
Looking at the datasheets, I think I probably can put them into the circuit and they'll work just fine without changing other components.

Would that work and sound better, or would I probably get problems with too small heatsinks or the amp's main PCB which is perhaps too weak for the power needed by the IRFP9140/240 and IRFP140??

[ilimzn]

Simply put: NO
You are mixing data about the characteristics of the MOSFETs with their intended application, which is one of the Pass ZEN amps, where there are certain speciffics that do not apply to your amp.
What you could do is, replace IRF540 with IRFP240 (NOT IRFP240N) and replace IRF9540 with IRFP9140 (NOT IRFP9140N). Keep in mind that these come in much larger cases (TO247) which you may not be able to fit on the existing heatsink without modification. Alternatively, you may use IRF9540 and IRF640 for better complementarity compared to original parts, but the IRFP parts are even better at that, including other benefits. The down side is that it is becoming very difficult to get the non-N suffix versions, which are quite different than the ones with the N at the end.
Even so, I doubt this would be the place where some modding would give you the most benefit... to make a more educated guess, one would have to see the schematic diagram.