Infinity FET Preamp rebuild

The “right guy” would have been John Ulrick, the lead designer at Infinity Systems at the time. He also designed their class D amp known as SWAMP. He went on to form Spectron Audio. He passed away a few years ago.

The likely issues might be aged parts. The solution would be to replace all resistors, caps and FET’s with premium parts, and replace the internal wiring with quality Dueland wiring. Any competent service shop should be good enough to handle this work. Should not run more than $1,500 in parts and $500 in labor. 

I realize what you are saying.  You hear horror stories and this is a very rare piece, so I want to be careful who I take it to.

I’d recommend his accomplice, Arnie Nudell. Regrettably, Arnie has also passed away. 

Thanks, thanks, thanks for the humor, how about some real help?

I'd probably recommend something very basic, unless there are switching problems.

There's only a handful of electrolytic caps. Go ahead and have all of them replaced with modern best of breed.

Panasonic FM or Nichicons wherever possible. I think there's a total of six or eight caps total.

Best,
E