How do you know what kind of caps to use?

[buildafriend]

I've been noticing a lot of projects do not list what kind of caps to use! like this one for example:http://www.tonepad.com/getFile.asp?id=108

How do you figure out or know what kind to use?

What are polarized caps usually doing or what are they used for?

Where would I want to apply ceramic caps to my circuit ? what are they most commonly used for ( in audio circuits, I'm aware they are in tons of things ) ? What effect do they have on the sound?

Where would i want to apply poly film caps to my circuit ? What are they most commonly used for ( in audio circuits, I'm aware they are in tons of things ) ? What effect do they have on the sound.

What effect do carbon composition / metal / and carbon film resistors have on the circuit?

What effect does germanium vs silocon transistors have?

[phector2004]

Hmmm, for capacitors, you need to find ones that capacitate and that fit in your board. (Avoid giant supercaps and automotive capacitors, etc for stompboxes) 

I've used all types without problem. Some look nicer than others, or have more mojo, etc. but all of them should work.

Polarized (tantalum blood capacitors, electrolytic capacitors) caps are polarized because of their construction, not the circuit's design in particular. You can get a lot of capacitance out of a small capacitor, with polarity being the unfortunate tradeoff. You can also buy/make unpolarized electrolytic capacitors, but I'll let you Google that on your own.

Carbon comp resistors have "mojo", but also distortion at high voltage swings (not stompbox... R.G. has a really cool article on these.) Carbon film are the "standard," with 5% tolerance (within 5% of the stated value)
Metal film are the "accurate" variety as they all fall within 1% of the stated value.

Germanium transistors produce smoother clipping (I think) and are generally a pain in the ass to work with. Silicon are more modern, easier to find, and less likely to have you kicking your stompbox across the room when it doesn't work!

[JKowalski]

They don't list it because it really doesn't matter. Except for the polarized part. Polarized caps need to have the voltage drop across them be a certain way to work properly. Think of a supply filter cap. There will always be voltage across them the same way (the power supply voltage). However, if you put an AC signal across them, then the polarity of the voltage will switch every half cycle of the wave and that's not sticking to the rule. The way you can get around this (use polarized caps for AC) is in situations where the AC signal is coupled to different voltage levels. For example, take the input to most 9v effects. The signal comes in coupled around ground, 0v, and on the other side of the input cap it is coupled to 1/2Vcc (with 9V, 4.5V). Even though there is an ac signal, there is always the 4.5V difference between the sides keeping it polarized. Polarized caps are usually Electrolytics and Tantalums.

Nonpolar caps - you don't have to worry about an of this. Negative/pos can be switched whenever. By analyzing the circuit, you should be able to tell where constant voltage drops will be across capacitors and thus where you are allowed to use polarized caps. The rest of the caps must be nonpolar.

Now, components. 99% of the "which is the best" discussion surrounding passive component "sounds" is BS. The main difference between cap types has to do with tolerances, reliability, temp variations... Things that people who build effects shouldn't care about very much at all. The "sound" of a capacitor doesn't mean anything. The only sound changes you get from using capacitors is in the context of the circuit. A cap can't be "transparent" or have "perfect high range" - it doesn't make any sense. The way the cap is used in a circuit will determine that kind of change.

It's the same thing for resistors. The main differences are tolerances and temp variations. Metal film are the best in my mind because they are cheap as chips and have the best qualities (temp invariance, high tolerances). Thats not to say that those things matter, but why not buy the components with the best specs when they aren't more expensive? Carbon comp "mojo" is BS. They are just worse quality resistors (5%-10% tolerance, high temp dependence). A resistor resists. There's no magic difference that alters your sound between types.

Finally, transistors. Germaniums are actually different from silicon. Their curves are slightly different. That isn't to say all the hype about them means that you should replace every Si with Ge. There's nothing wrong with Si.

Again I have to emphasize that the components aren't the determining factor - the CIRCUIT is. Build your circuit to what you want and then choose components for it that are appropriate considering the following:

A. Product enviroment (where the circuit will be used and conditions it will be subject to)
B. Required tolerances (how finicky the circuit is to slight variations in components)
C. Reliability (how long you want it to last)

D. Quirks of different types of components (this stuff is more applicable to RF, high power, not what people do here.)

I've been noticing a lot of projects do not list what kind of caps to use! like this one for example:http://www.tonepad.com/getFile.asp?id=108

How do you figure out or know what kind to use?

What are polarized caps usually doing or what are they used for?

Where would I want to apply ceramic caps to my circuit ? what are they most commonly used for ( in audio circuits, I'm aware they are in tons of things ) ? What effect do they have on the sound?

Where would i want to apply poly film caps to my circuit ? What are they most commonly used for ( in audio circuits, I'm aware they are in tons of things ) ? What effect do they have on the sound.

What effect do carbon composition / metal / and carbon film resistors have on the circuit?

What effect does germanium vs silocon transistors have?

[G. Hoffman]

What are polarized caps usually doing or what are they used for?

For the most part, the polarized caps are used for higher values (over 1μF).  Non-polarized are for lower values.  Ceramic and film are largely interchangeable by your choice, though at pF values ceramics seem easier to find. 

Metal film will usually be quieter than carbon, but that should only be an issue at higher voltages, so not really a concern with pedals.


Gabriel

[phector2004]

Carbon comp "mojo" is BS.

It obviously isn't!   
After all, they're made of magic and unicorns!! 

I think we all forgot to mention, older resistors (Carbon comps) and transistors (i.e. germaniums) also tend to hiss more than the new stuff. So choose your stuff wisely, EBay NOS transistor salesmen aren't usually there to cater to your needs.

[petemoore]

  Some read the bottom line.
  Others read all the lines.
  Others yet read between the lines.
  Then there are those who've read enough lines to read between them, and know where exactly where the bottom line is for them.

[R.G.]

I've been noticing a lot of projects do not list what kind of caps to use...How do you figure out or know what kind to use?

Like the guy who asked the New York cabbie "Hey, how do you get to Carnegie Hall?"; practice, man - practice!

You go dig in and learn.

Capacitors are produced in such a profusion because they're imperfect. It's hard to get enough capacitance with enough voltage, with low enough internal resistance and inductance in a small enough size package for a cheap enough price. You're always trading all of these off. The way to learn what kind of cap to use is to learn (a) what kind of caps exist, and (b) what each kind of cap is good for, or more importantly what they're bad for and to be avoided.

What are polarized caps usually doing or what are they used for?

Polarized caps are used where you can't get enough capacitance in a small enough package or cheaply enough to do it any other way. Polarized caps sacrifice performance to get small size and low price.

Where would I want to apply ceramic caps to my circuit ?

You want to apply ceramic caps where you need a low ESR, good high (i.e. megahertz) frequency response, and can sacrifice drift, accuracy, and a certain graininess some people claim they hear.

what are they most commonly used for ( in audio circuits, I'm aware they are in tons of things ) ?

Power supply bypass for high frequencies, noncritical audio signal and filter circuits, and in low values for filter setting.

What effect do they have on the sound?

That is too complicated a question to answer here. Many flame wars have been fought over this point. Same for all other instances of this question. There is a huge number of issues lurking under this rock.

Where would i want to apply poly film caps to my circuit ?

Where you want accurate time constants/filter frequencies and can sacrifice the space to use them and their price.

What are they most commonly used for?

Audio filter and frequency determination in filters.

What effect do carbon composition / metal / and carbon film resistors have on the circuit?

Carbon composition resistors have excess noise that's missing from metal film and mostly missing from carbon film. Carbon comp can have a slight desirable distortion where the signal across the resistor is upwards of 75V or more of signal swing. There is almost none of this distortion in small signal circuits.

What effect does germanium vs silocon transistors have?

By themselves, none. You cannot rub germanium on a circuit and have it sound better. Each has its own set of peculiarities, and when used in a particular circuit may have audible differences. Circuits matter. The devices used in them may or may not.

These are the obvious questions that occur as you read the seething hash of semi-information on the net. Every one of these issues has been perverted as a hook to hang advertising on. There is no substitute for doing the actual learning, and it's a long path, not a response to one post.

[buildafriend]

I want to thank you all for the amazing advice. It has put me on a high level of thinking and has helped me to apply my learning in greater ways. This endeavor has become one of the most addicting ones I have ever gone on, and its honestly helped me a lot in stepping up my abilities in the recording studio world. After viewing these responses I now know what it is that I must do, and that is to experiment and build, and build, and build.

Though the least informative technically, I must say that the following has helped me to realize what is happening here. I think it's very quotable. This person has answered almost every question I have had. Thank you x10. 

  Some read the bottom line.
  Others read all the lines.
  Others yet read between the lines.
  Then there are those who've read enough lines to read between them, and know where exactly where the bottom line is for them.