i got some BurrBrown opamps

[Gila_Crisis]

i have 4 BB opamp, all single opamp. those are an OPA37, OPA121, OPA620 and OPA637.

do you think i can use them in place of a LM741 or LM308, in my opamp Big Muff?

i looked at the datasheet and say that the 637, 37 ahve application in professional audio equipement, the 620 is good for ultrasound (?) and low noise preamplifier, the 121 seams not to have "musical" applications

all 3 got the same package as a 741/308

[PerroGrande]

All of the amps you listed are pin-compatible with the LM741. 

Of the bunch, only the OPA620 comes with a caveat -- the 620 is designed for +/- 5V operation.  You'll be okay if you're using a single 9V battery as a supply (either single polarity or split +/- 4.5).  If you're using something larger, (like 2 9V batteries), the 620 will get fried.

The 637 is NOT unity gain stable, so don't try to use it as a buffer!  The stage in which you try it must have a gain of 5 or more. 

apart from those caveats -- try 'em out and see if you like the sound.