Moog Music Forum

dr_floyd wrote:Just curious, what was the original opamp that you replaced with the TL074?

Hey Again
And sorry for not answering your quistion a bit faster

The original one, is called: this is what is printed on the OP AMP
(M9424DP
LM324N)

Best regards
Morten

LM324? No wonder the new one sounded better, those LM324s weren't designed for audio!

(Adds Voyager opamp inspection on to-do list for bench)

MC wrote:LM324? No wonder the new one sounded better, those LM324s weren't designed for audio!

(Adds Voyager opamp inspection on to-do list for bench)

I cant tell you if it´s the same in all Voyagers..
but if its the same in yours.. change it quick.. and get a grin on your face

MotneN wrote:

dr_floyd wrote:Just curious, what was the original opamp that you replaced with the TL074?

Hey Again
And sorry for not answering your quistion a bit faster

The original one, is called: this is what is printed on the OP AMP
(M9424DP
LM324N)

Best regards
Morten

Cool! But what's the part designation? It should be printed on the board, next to the op amp. Probably something like a "U" + a couple of digits. Like U3 or U27 or U124 etc. And was it mounted in a socket or did your friend have to de-solder the original op amp?

Regards
/Jonas

Oh, and there a few variations of the TL074 op amp, usually designated by additional letters, like TL074A, TL074ACN etc. Do you know which one you have?

slirak wrote:Oh, and there a few variations of the TL074 op amp, usually designated by additional letters, like TL074A, TL074ACN etc. Do you know which one you have?

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

slirak wrote:

MotneN wrote:

dr_floyd wrote:Just curious, what was the original opamp that you replaced with the TL074?

Hey Again
And sorry for not answering your quistion a bit faster

The original one, is called: this is what is printed on the OP AMP
(M9424DP
LM324N)

Best regards
Morten

Cool! But what's the part designation? It should be printed on the board, next to the op amp. Probably something like a "U" + a couple of digits. Like U3 or U27 or U124 etc. And was it mounted in a socket or did your friend have to de-solder the original op amp?

Regards
/Jonas

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...

GregAE wrote: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.

muksys wrote: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).

slirak wrote: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

muksys wrote:

slirak wrote: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.