Acoustat servo amp help needed

mark100

Member
2010-12-24 5:49 pm
Hi all, bringing some Acoustat X's out of a long retirement (put em in a closet in 1981 )

What is a modern op-amp, and where do you get them?

Also, looks like a bad tube took out a 10K 5w resistor, and I read in the service manual I should change it and a 10K 15w one as well.
Can anybody point me to a supplier for these?

Many thanks in advance! and happy holidays to all!

mark
 

hella356

Member
2009-02-17 11:24 pm
IMO, the best place to start is to contact Michael Savuto at Analogue Associates. He specializes in the Servo amps. (AFAIK, they work on nothing BUT the Servos.) You can either send the amps to him to work on, or purchase parts from him if you're handy with electronics. He has upgrade parts that were selected (& some specifically made) for the amps, for both sound quality & reliability. I can't afford it now, but I plan on doing a complete overhaul of my Servos, eventually. The people that have done his upgrades seem to be unanimously blown away by the improvements. Mike is a good guy, too. Very helpful. [email protected] is the address.

Good luck!
 

hella356

Member
2009-02-17 11:24 pm
According to the schematic I have, the original op-amp is an LF347N. Per a conversation with Savuto about a year ago, I recall there ARE a number of functional equivalents, and that they had tried a bunch of different models before settling upon the one they thought sounded best and which they sell as a straight replacement. Their higher level op-amp mod actually does away with the quad unit entirely.

If you need a schematic, I can help you out. Best of luck, be sure to let us know the results of your testing!