Acoustat servo amp help needed

mark100 · 24th December 2010, 04:58 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 · 24th December 2010, 05:34 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. acoustataallc@gmail.com is the address.

Good luck!

mark100 · 26th December 2010, 02:46 PM

Thank you, I may end up taking that path.

Right now, I'm still on the DIY hunt ... hoping someone can recommend an op-amp and a good on-line source for electronic parts in general. (I'm OK with a soldering iron and basic circuit testing.)

hella356 · 26th December 2010, 03:59 PM

Savuto does have upgraded replacements for the opamps in the Servos. The most recent price sheet I have lists the price of the quad IC + new socket at $30. He also has a more advanced version which requires a bit more work & parts.

mark100 · 27th December 2010, 02:15 PM

And another thanks!

Still hoping for a few op-amp suggestions....wouldn't mind experimenting..

hella356 · 27th December 2010, 04:24 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!

gootee · 11th January 2011, 05:54 AM

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ktuuri · 13th January 2011, 09:57 AM

Give Michael Savuto at Analogue Associates a call, he has resistors and Opamps you can buy and DIY. I have got some parts off him in the past. The Opamp that he sells is a very good upgrade over the stock pieces.

24th December 2010, 04:58 PM	#1
mark100 diyAudio Member Join Date: Dec 2010	Acoustat servo amp help needed 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

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24th December 2010, 05:34 PM	#2
hella356 diyAudio Member Join Date: Feb 2009	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. acoustataallc@gmail.com is the address. Good luck!

26th December 2010, 02:46 PM	#3
mark100 diyAudio Member Join Date: Dec 2010	Thank you, I may end up taking that path. Right now, I'm still on the DIY hunt ... hoping someone can recommend an op-amp and a good on-line source for electronic parts in general. (I'm OK with a soldering iron and basic circuit testing.)

26th December 2010, 03:59 PM	#4
hella356 diyAudio Member Join Date: Feb 2009	Savuto does have upgraded replacements for the opamps in the Servos. The most recent price sheet I have lists the price of the quad IC + new socket at $30. He also has a more advanced version which requires a bit more work & parts.

27th December 2010, 02:15 PM	#5
mark100 diyAudio Member Join Date: Dec 2010	And another thanks! Still hoping for a few op-amp suggestions....wouldn't mind experimenting..

27th December 2010, 04:24 PM	#6
hella356 diyAudio Member Join Date: Feb 2009	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!

11th January 2011, 05:54 AM	#7
gootee diyAudio Member Join Date: Nov 2006 Location: Indiana Blog Entries: 1	Mouser Electronics - Electronic Component Distributor Electronic Components Distributor \| DigiKey Corp. \| US Home Page

13th January 2011, 09:57 AM	#8
ktuuri diyAudio Member Join Date: Nov 2007	Give Michael Savuto at Analogue Associates a call, he has resistors and Opamps you can buy and DIY. I have got some parts off him in the past. The Opamp that he sells is a very good upgrade over the stock pieces.