No ..i cant remember which one it was.. but i can ask my friend.
he told me that he bought some other ones, that we also could try..
so maybe we haven’t found the best one yet…
best regards
Morten
I think it was mouted in socket..i´’ll ask him 
best regards
Morten
The TLO74 seems to be the op-amp of choice for at least a few of the modular system makers I’m familiar with. I have a Synthesizers.com system that includes modules from them and from SSL, and both manufacturers use the TLO74CN in a lot of designs.
I may have to open up my Voyager for a peek…
It is certainly worth trying..
maybe it because i got use to the way the voyager sounded, before
the new OP amp was put in .. but i really think it made a HUGE difference
on my voyager.. a much more ballanced and mellow sound.. really nice
best reagards
Morten
The TL071 is a low noise opamp optimized for audio. The TL074 is the quad version of the 071.
So, I just took a peak into my OS and found the headphone jack is driven by an LM837, which is designed for “professional audio applications”. It’s the same pinout as a TL074, so I wonder if this was something that was caught and corrected with new boards. Mine is from the second run of OS’s.
Pretty likely. I’ve had a short conversation with Moog’s support about an issue I have with my early SE, and they said that they “have added a number of stability and noise reduction modifications to the analog board” since my SE was made.
There are several versions of the LM837 too, LM837, LM837M, LM837MX etc. What exactly is your 837 called? What brand? (Texas Instruments, National Semiconductor etc).
LM837N National Semiconductor
Great, thanks! Now I just gonna have to figure out if it can be used as a drop-in replacement for the LM324N or if some other components will need replacing too. That’s out of my league, so if anyone knows already, any hints would be greatly appreciated.
It should be an easy switch out. Just remove the LM324N and put the LM837N in its place. 
So no electrical differences that would require, say, a different resistor value here or another cap value there?
That sounds great! Now I just need to find the time to dig in to my Voyager. Will report back with before and after recordings.
324, 837 & 074 are pin for pin the same. All are interchangeable. Shouldn’t need any other changes. Be sure to drop in an IC socket for easy swappage in case it’s not to your liking.
Thanks! Yeah, I certainly will use a socket. If it’s not socketed already, I guess I’m gonna have to to take the appropriate board out in order to de-solder the 324. So looks like a project for the upcoming weekend.
It seems this replacement may already be done by a tech, in an (unsuccessful) attempt to solve an issue I’m having with a “crackling” noise.
The replaced opamp is designated U49. Anybody happen to know if that’s the opamp we’re talking about here?
Thanks!
/Jonas
I’m out of town ATM, but I’ll check when I get home tomorrow night.
Thanks, great!
Opened it up last night. Yep, U49 is where I was looking.
OK, thanks a LOT for looking! Saved me a bit of head scratching there…
Well, I read somewhere on this forum that three opamps could need replacing, to fix issues with the output section of early models. I’m just gonna have to try and find out which the other two are. If anybody have any ideas, it’d be greatly appreciated!
Anyway, if anyone’s gonna do the U49 swap, you might consider changing two resistors too:
http://forum.moogmusic.com/viewtopic.php?f=2&t=1714&p=34012&hilit=U49#p34012
Thanks again muksys!
/Jonas
i´d really like to have a blind test on this with the same volume
Just so to be clear, I have no idea if U49 is the IC that was replaced MotneN. The 837 is designed for audio and should be fine. I do not know if earlier voyagers used different IC’s and were later changed to the 837, but if your’s has the 837 in it already, I’d suggest leaving it, unless it is bad, then swap it out for the same. Plus the resistor change that Amos suggested.