Need some help with a Peavey Delta Blues.

[StratTone]

I started working on this amp because of loud snap crackle pops. haha Anyway I got that taken care of. Ended up being a resistor and a cap. Now when the amp is powered off however it make the loud squeal or chirp. I am real careful with amps and made sure not to damage any of those crappy wires connecting boards. I check and rechecked to make sure it wasn't something I did and looked over and over again at all solder joints. Didn't do it in the beginning but now is. Could it be a coupling cap?

[Don Moose]

Does it squeal with the reverb all the way down? Sometimes op-amps will squeal as their power supplies collapse.

More likely something else, though.

[StratTone]

Boy is that crap on my face. No squeal at all. What a crappy design. Will a TL072 do the job any better. Might have the part number wrong but I think that is it. These things really do need a standby switch.

Does it squeal with the reverb all the way down? Sometimes op-amps will squeal as their power supplies collapse.

More likely something else, though.

[Enzo]

STandby switch is a waste of parts and labor on an amp this small. If all you want it for is to miss out on a power down noise, then turn the reverb pot down. Lots of amps make noises when power turns off.

Changing the 4558 to a TL072 is no more likely to change things than simply installing a different 4558. I don;t see an excess number of failures with this design, seems to work OK in my experience. Now and then you have to replace one, but I replace a ton more reverb pans than drive ICs. I think replacing the reverb pan is THE most common repair I do to Fender Blues Juiors.

[Don Moose]

Horses first, then zebras. It's usually something simple.

Any good, low-noise audio op-amp will work - most of the 8-pin duals have a common pinout. You could work though the selection guides on the National, Linear and TI websites, or see which of those your favorite supplier has for cheap.

Hope this helps!

[Enzo]

I have no idea on this, but since the op amp has to drive the reverb pan transducer, it is conceivable that some op amps might not be as happy driving that load as others. HAving said that though, I would myself stuff most any op amps I had into that socket if the need arose.