Capacitor questions

[1wahfreak]

Howdy,
I'm getting ready to order some parts for a Tubescreamer build and need to know what type of caps to order. I have a few values from other projects but I'm not sure if I can use them.
Example: I have 2 packages of .1uF caps but they have different ID numbers, Mouser# 140PF1H104K and 140PM2A104K. I believe they are both Polyester Film so what's the difference and which one do I use?
The BOM also calls for a 0.047uF, 0.02uF, 51pF. Are these also Polyester film?
My other questions are: How would I know why type of cap. to order if the BOM only states the value. When I look at the schematic, it doesn't specify what type. How do I know when to use and electrolytic or a tant. or a PF?

[javacody]

Anything over 1 uF is usually Electrolytic or tantalum. Usually anything in the picofarad range is ceramic (or polystyrene, which is supposed to sound better than ceramic). In between you have the polypropilene and polyester amongst others. I would get the cheapest ones (rated at 25v at least) you can find.  

Some people swear by different capacitor materials sounding better, others don't. I'm one of the former.  You can socket the more important caps (the input and output cap) and swap cap types to see if YOU hear a difference. Good luck with your build!

[brett]

Probably the most important choice in tubescreamer caps is whether to make the 2 x 1uF NP an electrolytic type or a film (MKT) type.  The former are much cheaper ($0.35 vs $2), and are the original part.  If you want a non-original, but slightly better (IMO) sound, go for MKT 0.22uFs and 1.0uFs, and replace the 4558 chip with an NE5532.

[Brian Marshall]

i'd upgrade all the cermaic caps to film caps...  I dont like the sound of most ceramics i've tried to use.  They are the only ones i can tell a difference with.

[Boofhead]

The 140PM2A104K's are a minature type, ie. the package is slightly smaller, that's about the only difference.

For non-polar in audio typically use:
Ceramics for < 1n
Films for 1nF to 1uF (can get upto 10uF at a price)
Non-Polar electrolytics (NP) for > 1uF (can get down to 100nF).

There's overlap in the 220nF to 2.2uF region basically you trade quality vs package size and performance.

Electrolytics and tantalums are are polarized.  Generally use electrolytics unless tantalums are specified.

In some circuits you can interchange electrolytics and non-polars- provided you get the polarity correct in the circuit.