Quote Originally Posted by thegnu
Again a little further off-topic, if you had a device you were trying to lower the noise floor in, and you changed out the capacitors based on Some Internet Guy's advice, but it made no difference, and it had 2N3906's in it (the PNP version of the 2N3904's, to my knowledge), would you swap them for something else? And what would you swap them for?

This device is a Boomerang+ phrase sampler.
The transistors won't make too much of a difference in most guitar effects circuits. Shielding all the wires carrying signal within the unit, using carbon film or metal film resistors instead of carbon comp, ensuring good ground connections (all connections really, not just grounds) etc... will make more of a difference than just changing the transistors.

That said, if i was building a circuit from scratch i would just use the better transistors as there is little cost differance; but i wouldn't bother to mod an existing circuit just because of them.

Better opamps can help; changing 4558 chips to NJM4580, NE5532, or the OPA's will help. I would, however, shy away from the OPA and burrbrown type opamps as they are almost TOO good for some circuits. They can introduce noise and oscillations unless the circuit layout, grounds, etc... are perfect

Caps won't make much of a difference as long as they work. Using poly or mica types for power supply bypassing (battery or whatever) will actually make things worse as ceramics are more suitable. Then again, i don't go for the audiophile "this cap sounds better than that cap" nonsense. :

All IMO.