Hey there, I'm building this pedal (https://dirtboxlayouts.blogspot.com/2019/07/ibanez-maxon-sd9-sonic-distortion.html), and I was wondering if it's possible to swap out both the 680nf and the 1uf polypropylene capacitors with electrolytic capacitors. If so, could someone help me make sure I get the polarity right?
Yes, it's possible, but electros have wider tolerances than film caps as well as other side effects.
You may not be able to get 680nF caps in electrolytic easily. For the 680s, the pin of the cap that connects to the opamp pin is the most positive one; put the + terminal there. For the 1uF, the pin that connects to the 10K is the most positive one.
You don't mention why you're doing this. I could guess that you have electros, but don't want to order the real parts. That's fine - I'm a big believer in getting something running, then ordering the perfect parts later. You could replace all of these with 1uF electros (same polarity notes) without much change in sound. They will all have a small effect on the amount of bass, but that may not be a big issue in the sound. If you're after the "original" sound, order the film caps while you enjoy the first pass of the pedal with the electros. Electros being not as accurate will affect the tone a little.
Thanks a lot. You're right, I don't have 680nf film capacitors at home. Are there any recommended film caps for high values like 680nf or 1uf? (The 560nf I have are already pretty large.)
680nf are generally available in tantalum form. Maybe I'm wrong, but I gather tantalum are not recommended in series with an audio signal.
(https://i.imgur.com/4VmCP07.png)
edit: R.G. already answered..
P.S.
There are non-polarized electros too..