Threshold S300 Power Amp

I had an S300 in the mid 80s that sounded decent but kept popping fuses so I got rid of it for a Classe 25 that had much more oomph. Eventually traded that guy for a CA200 with side heatsink (basically a CA201) that sounded even better along with a McCormack 225. With amps like Classe and McCormack that can be had for 1000 - 1500 there’s really no reason to buy a used Threshold of that era.

johnjohn, the amps you mentioned are all nice, but each might be preferred in different systems.

Unfortunately it suffered from a very wicked turn-off transient, about a minute or so after the power switch was turned off.

I had the S300 Stasis MkII with optical bias, it never had this problem, a few others dry caps and such, but I fixed all those and gave it all most double the uf’s in the power supply, tightened the bass it was a nice amp.
Nelson said to me over at DiyAudio to bias it up higher so on a 30c-35c day you can just keep your palms on the heatsinks for 6 sec then have to remove, bricklayers need not apply.
If anyone needs I still have all the circuit diagrams and adjustments for it. First to get them has to spread them around.

Here’s an old shots of him when he was into esl’s I posted at diyaudio he got a kick out of, I believe this was a Plasma and not an ESL.
http://airspeaker.co.uk/Nelson%20Cover.jpg

http://airspeaker.co.uk/9108CMTHR-IMG-JS-Ionic.jpg

I have a pair of these from 10khz up on my ESL’s
https://www.ebay.com/itm/Magnat-Plasma-MP-02-ion-tweeter-massless-air-plasma-speaker-Plasmahochtoner...

Cheers George

The OP must like that amp. That thread is over nine years old!

When Jon Soderberg of vintageampair.net (the guy for all your Threshold/Forte' maintenance needs) refreshes these amps; one of the things he routinely suggests is the replacement of the power switch (circuit breaker).