Which opamp in this preamp circuit?

lordearl · 22nd January 2012, 04:38 AM

I recently dusted off this ebay-bought pcb I had sitting in a cupboard for a year or so. Whilst I do have the schematic (see pic below) and recall that the circuit uses 2SK170 and 2SJ74, I don't recall what opamp it was designed for. Is anyone able to assist?

AndrewT · 22nd January 2012, 09:54 AM

Is it a single or a dual?
It needs to be unity gain stable.

KatieandDad · 22nd January 2012, 10:28 AM

If in doubt build it with an IC socket.

Then you can swap Op-Amps without compromising the PCB tracks.

Use a nice gold-plated turned socket - they're not expensive.

john curl · 22nd January 2012, 11:36 AM

I would use an AD825.

lordearl · 22nd January 2012, 11:37 AM

Quote:

Originally Posted by AndrewT

Is it a single or a dual?
It needs to be unity gain stable.

Definitely single - there is one socket per channel

How did you determine it needs to be unity gain stable?

What is a good starting point for a unity gain stable DIP single channel opamp, which runs at +/-15v?

lydlaug · 23rd January 2012, 07:14 AM

Hi

It seems to be the same schematic as on this one
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

And they stated to use OPA627.

22nd January 2012, 09:54 AM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Is it a single or a dual? It needs to be unity gain stable. __________________ regards Andrew T.

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22nd January 2012, 10:28 AM	#3
KatieandDad diyAudio Member Join Date: Nov 2011 Location: UK	If in doubt build it with an IC socket. Then you can swap Op-Amps without compromising the PCB tracks. Use a nice gold-plated turned socket - they're not expensive.

22nd January 2012, 11:36 AM	#4
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	I would use an AD825.

23rd January 2012, 07:14 AM	#6
lydlaug diyAudio Member Join Date: Nov 2004 Location: Stavanger	Hi It seems to be the same schematic as on this one eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices And they stated to use OPA627.

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