Upgrading Power Supply Caps

If you're talking about the large can caps, I renewed the ones in a Threshold S/300 Series II a few years ago. I searched the web for electrical equivalents. Then narrowed it down further to which ones were identical in size. Since my plan was preventative maintenance, finally I chose what was in there to begin with - computer grade Mallorys - only slightly higher in voltage and capacitance; exact replacements were no longer being produced. The Mallory website showed how many of each type were on hand and pointed me to an electrical supplier who could get them.

The switch out was simplicity itself, requiring only a screw driver. Nonethless, keep notes on the postions of the fasteners, the wiring and the orientation of the plus and minus signs marked on the caps.

I hear the rectifier bridge benefits from replacement at the same time but I didn't bother. When it was all done the amp was a maybe a little smoother and more liquid but it could have been my imagination. The main improvement was to my peace of mind.

Mprime, come to think of it here are a few other observations. The Forte 4A was perhaps the most well received amp in Forte's brief history. While the compulsion to get more of a good thing is very persistant in audio, consider preserving the balance the 4A already possesses.

Upping the storage capacity of the large can caps significantly, say more than 25%, may necessitate a new bridge rectifier. Go too far and you'll need a bigger transformer. How much sleep do you want to lose :^)

In short, I'd look for 7A monoblocks before I went off the deep end modding an already terrific product like the 4A. Of course no condition is permanent so whatever you decide, have fun with it!