op amp for EMT 140 w/ 162?

Before I re invent the wheel, has anyone replaced the 709C op amps in an EMT 140 reverb with the 162 amp module (solid state version). I can not find these critters anywhere, but it seems like aomething else should work. It follows a jfet from the pick ups, and feeds a transistor drive / transformer output....

Boy, someone must be eating these.

In London England: http://www.cricklewoodelectronics.com/
search "709"
Part No.: LM709CN IC Op Amp 8DIL Price: £3.00
Part No.: LM709CH IC Op Amp TO99 Metal Package Price: £3.00

Amsterdam, The Netherlands http://www.vintageplanet.nl/index.html
LM709CN (uA709CN) General Purpose Op Amp . . . . . . . NOS 1.98 2.35 uA709-CN

Thief River Falls USA: www.digikey.com
search "709", select "single"
LM709CN-ND Non-Stock
LM709CH-ND Non-Stock
LM709H-ND Non-Stock

Do you have a link to a better schematic?

http://danalexanderaudio.com/EMT/EMT162TS.jpg is tuff on the eyes.



Looks to me like it runs a gain of 15 to 40, has no particular drive or bias demands. All the later opamps were made to target 709 sockets. Snip the 709's compensation caps (or don't insert pins 5 and 8 of the replacement chip). Get a single opamp. 741 will be very similar in use. TL071 may be a tad faster. DIP-8 pins can be bent round to fit round-8 sockets.

Niels - I have a few lm709's that came out of my auditronics 110- how many do you need?

Hey Nielsk, I did a change of the 709 to a NE5534 a few years ago,and I can certainly recommend it. Remember to put in the 22pF comp.cap, even if the gain is higher than 3. It became a few dB less noisy.
Cheers Bo

Wow, thanks for the replies
I think changing to a 5534 sounds like the best approach, you mean a 22pF cap between pins 5 & 8, correct? I have never used the "balance" pin 1 on these.... would anything else in the circuit need to change?

Niiels - yes between pins 5 and 8. ive changed out quite a few 709's with 5534's in my console. I have pdfs of the original auditronics notes on changing them out. they are really helpful. pm me your email and i will send them to you. my documentation recomends installing caps in paralell with the feedback resisitors to limit bandwith and prevent oscillations in super high frequencies, like in a 312. in my case it was 150pf caps, but it depends on the value(s) of the feedback resistor (sorry, i cant really read your schematic). here is really good thread on choosing that cap value: thread

Bo- It became less noisy just from adding the 22pf comp cap?

-Ben

Hey, the 22pF to make it stable and yes it´s less noisy with a 5534.
Cheers Bo

I did excange the 709  with 5534 in one channel yesterday.
Sound has improved a bit. It´s a bit more clear now.
Noise dropped about 2-3dB, but Signal seems to be down in this channel a bit too. Maybe it was not calibrated well in the first place. Didn´t check it before soldering. I will change channel 2 today. Sounds better anyway.
Thanks guys!!!