A little of topic, but a kid asked me today how to install a capacitor on my thread on another forum... so here is a quick post if anyone else is wondering the same thing...
When you are going to connect a large capacitor into your sound system power supply... You need to think of a few things...
1) Make sure it is strapped down... you don't want it floating around.
2) Make sure it cannot be accidentally shorted.
3) Make sure it is on a circuit breaker or a fusible link.
4) Mount it in a way that no one can accidentally touch it (this can KILL someone).
5) Mount it as close to the amps as possible... this will reduce the amount of power loss (I don't' have time to explain the laws of thermodynamics to everyone, so just push the "I believe button and go with this rule of thumb).
6) When you're ready to charge it for the first time... use a test light to charge it... This means, DO NOT connect the power wire directly to the battery yet... leave the end of it unhooked, and use a test light to connect the end of the main power line to the battery... this gives the power circuit a load and prevents a short circuit condition (which will kill your battery and blow your main charging circuit fuse). If you are not sure how to do this correctly, ask a friend to help you.
7) Keep your ground line as short as possible... less than 2 feet is recommended. Less than 1 foot is ideal.
8) A good rule of thumb is 0.1 farad for every 100 watts of power you're using. Not just on the subs, but for the whole system. You can use individual caps per amp OR you can use one big one (I'm running a cap bank, which is to say that they are all wired in parallel, to provide me with "one" large capacitor... when wired in parallel the capacitance is seen as one and they add incrementally... so my 1/2, 1/3, & 1/4 cap are seen as 1 cap with a 1.1 farad charging capacity).
8a) You can go with more capacitance than my rule of thumb, but in general, it is a waste of money... however, if you're running 1200 watts, and have to choose between a 1 & 1.5 farad... ALWAYS ROUND UP... e.g. get the larger capacitor.
9) Don't ever use power wire that cannot handle the current flow of instantaneous discharge of your power cap... if you do, you risk an electrical fire. If you are not sure what size wire to use, then go to a professional and ask or let them do it for you.
10) Almost forgot this one... Most caps are polarized (+/-) make sure you hook them + to + and keep the polarity in sequence with your battery and stereo power inputs. Could result in an expensive mistake if you don't pay attention.
I hope that doesn't sound condescending to anyone... it's not meant to be such... but I cannot stress this last part enough...
If you do not know what you are doing, get someone to help you the first time... I'd rather hear that a kid was shown how to hook it up right, rather than hear that he shorted the circuit, and it killed him.
A little off topic for my thread, but I hope that was helpful for anyone that reads it...