Coupling Capacitors

[helos]

Hello everyone, this is my first post in this great forum.
I'd like to ask you what do you usually use for coupling capacitors. I've seen many builds using only polyester film type, and other using also electrolitic. 

Any advise on this?

ps: sorry for my english...

[alanp]

Do you mean coupling caps in the audio path, or caps across power and ground, near noisy ICs? (Then again, they're decoupling caps, I guess.)

For audio-path caps, I try to use film wherever possible. (Electrolytic is used in these applications due to physical size, not because of any superior audio properties.) For power decoupling, anything goes.

[helos]

Do you mean coupling caps in the audio path, or caps across power and ground, near noisy ICs? (Then again, they're decoupling caps, I guess.)

For audio-path caps, I try to use film wherever possible. (Electrolytic is used in these applications due to physical size, not because of any superior audio properties.) For power decoupling, anything goes.

You're right, I had to be more specific. I've meant the coupling caps for audio-path.
So you use film for audio path? So if you have to use a 1uF cap you generally choose film instead of electrolytic? Is there a reason why film caps are better then  electrolytic for the audio path?

How about the power bypass caps? I generally use a 47uF and a 100nF (film), are these two caps (only) providing a good power filtering?

[WormBoy]

For guitar pedals, I would say that it does not make a huge difference unless you have golden ears and a low tolerance. In the audio path, I tend to go for film caps and good-quality electrolytics for the large values. Not because I have tested the audible differences between all contenders, but just because it makes me feel good  . Ceramic caps are said to be 'harsh sounding', though that may be a good thing in some circuits.

Bottom line: don't worry too much, check schematics/BOM to see what the designer calls for, and experiment if you like with alternatives (he, this is DIY after all).

[helos]

...Not because I have tested the audible differences between all contenders, but just because it makes me feel good  ...

Bottom line: don't worry too much, check schematics/BOM to see what the designer calls for, and experiment if you like with alternatives (he, this is DIY after all).

Eheh I think you're right! 

[WormBoy]

How about the power bypass caps? I generally use a 47uF and a 100nF (film), are these two caps (only) providing a good power filtering?

IMO, A lot depends on your power supply. If you have a well-regulated power supply intended for guitar pedals, you can get away with minor (or even no) filtering (although that likely also depends on what circuits you attach to it). In general, always adding at least an electrolytic is a good strategy, just to be safe: you never know under what conditions you need it to perform, and you might sell the pedal at some point. Some circuits require more careful consideration of power filtering; I am mainly thinking about things with LFOs that can tick very annoyingly.

I have some general-purpose adapters which are incredibly noisy when used with pedals. For those, I have built a small 'power conditioner' with an inductor, large electrolytic cap, 100nf multilayer ceramic, and 9V regulator followed by more caps. That keeps 'em real quiet.