Studer 269 - worth replacing LM301s?

[1954U1]

Hi,
I've just opened my recently bought 269 Studer 17ch mini-console,
and seen that all the LM301s [not a big number, 3 per input channel plus some others]  are socketed..
so, just for the sake of curiousity, I would try to replace the op-amps and see what happens to the sound..

I've read about the compensating cap issue..

What other op-amps do you advise to try?

Thanks a lot!

 

[inputoutput]

have you seen these ? ftp://ftp.studer.ch/Public/Products/Mixing_Analog/169-269/

Many good mod suggestions in the "mod" documents.  I´d check out and compare the other opamps before swapping the 301s. Change them on one channel, and compare with another. See what you like.

The later models came with other opamps, than the early ones. But they kept the 301s. (see schematics for more info). One of the good swaps if you have an external supply, is to change the 6,xV zener in the PSU to a ca. 7.5V zener.  1.3A (see the mod-documentation)

 

[Samuel Groner]

The LM301s are used in a hybride opamp, i.e. they bypass the internal input stage and replace it with discrete transistors. Not sure whether you'll find another opamp where you can do the same trick.

Samuel

 

[gyraf]

Yes, please don't underestimate the designers at Studer - and what they can do with standard parts...

Jakob E.

 

[StephenGiles]

Nothing wrong with LM301 at all.

 

[1954U1]

Thanks for the info..

Yes I've all the schematics and I've read through all the mods docs too.

I love the sound of this console, and its perfect for my kind of music.

What makes me curious about the LM301 is all the bashing around against this op-amp,
so yes I want to replace the LM301 in one-two channels and try to hear the differences.

Found so far as alternatives for the experiment: opa604 opa627 ne5534,
but yes, and many thanks Samuel for pointing this out, I dont know if the input bypass will
also work on these other opamps.

So.. do you think.. any risk of burning things other than the new opamps if I swap them?
I dont think so by watching at the schematics and opamps specs but I'm not really skilled.

 

[Bill Wilson]

The LM318 can also be used without its input circuitry. It is an old chip but has a slew rate of 70vus & is very smooth sounding.

 

[pstamler]

But also very prone to oscillation.

I agree that if you can get it stabilized the LM318 can sound very smooth. Quantum used it in the QM128's mic input stage with a good transformer (Jensen?) and it sounded excellent.

Peace,
Paul

 

[fazeka]

PRR had some good things to say about the 318:

http://www.groupdiy.com/index.php?topic=29081.0

 

[guy_4]

Hello All,
LM 318 was the opamp used by Ampex in the audio section of the  ATR-100.
Probably a good choice...
Best,
Guy

 

[L´Andratté]

Yes, please don't underestimate the designers at Studer - and what they can do with standard parts...

Nothing wrong with LM301 at all.

Dont. Do. It. Dont. Do. It. Dont. Do. It. Dont. Do. It. Dont. Do. It. Dont. Do. It. Dont. Do. It. Dont. Do. It. Dont. Do. It.


Or do it, but not after reading several threads about what accomplished people of this board have to say about "Op-amp swapping". Especially considering changing current requirements of the circuit vs. power supply capabilities.

I´d love to work with a 169/269, I´d change nothing only restore functionality if needed. Look how much thought has gone into these decks, every detail is neatly designed and well thought out.

In short if you have an antique yet still excellent mixer, why fxxk around with the circuit.

Btw. are the amps soldered directly or socketed?