Box-ster

Thanks for all of the great replies. If I think it is needed, I will look into upgrading the battery and alternator instead of a cap.

Paradroid_xA

Capacitors are the biggest waste of money imaginable.

Get yourself a decent alternator. There are quite a few places that will re-wind your existing alternator to give you a higher output.

The point of a cap is to deal with transient power draws that manifest themselves by the dimming of headlights, etc.

The truth is that aside from the occasional headlight dimming, you will get no practical benefit from a single cap. For example, if your amp puts out 100 watts at 14v and you see a 2v drop due to a spike in power draw, your amp's output would probably drop to about 80w. That's about 1dB, which is not perceivable. And if you have a decent amp with a regulated power supply it's debatable that you'll event see that much of an output decrease.

Again, a single amp or dual amp system will see no perceivable benefit from a cap other than (perhaps) decreasing the headlight dimming.

A battery upgrade and a high-output alternator are a much more effective way of improving performance during transient power draws.

And if you throw in the fact that most people don't properly calculate the size of cap they need and figure "well, it's a cap, it must be helping", you'll find that the cap is typically undersized and ONLY serves to eliminate headlight dimming. The draw at the amp remains the same and there is no performance gain in terms of audio quality and/or output.

STLBOX

I dont care how good your battery is or who rewound your alternator, neither discharge as fast as a cap. Really you need a cap, battery and upgraded alternator to make things optimal. It is not correct to say caps do nothing for audio quality/amp output.

Paradroid_xA

I said for a single and most dual amp scenarios, a cap will you give nothing but decreased headlight dimming.

In multiple amp scenarios with high draw, you're going to need all three as you've pointed out.

tanakasan

Agreed, and power/ground wiring of sufficient size installed correctly. Along with the "big 3".

onionescion

Caps are BANDAIDS!!!!!!!!!! and if you have regulated power supplies in the amp the are useless!!!!!!!!!!!!!!

STLBOX

Above is not true.

The current still needs to be pulled from the battery (rather than a cap) even if you have a regulated power supply. Pulling from the battery (any battery) sucks due to its slow discharge rate. A cap provide quick power for the amps. The cap still needs to be charged. That is where the upgraded bat/charging system comes in handy.

A regulated power supply in an amp doesnt "invent" power. I have had amps that actually shut off due to voltage drop.

ChefXB3

I am having the definate issue of dimming and an actual vehicle power loss when Im running at a high volume, I was actually logging on this am to get some suggestions and found this thread, I was thinking of a Cap, but I think the alternator and battery would be the viable solution for me. Im running a RF P4004 for my subs and a Pioneer GM6200F quad to my in car speaks. I also have an issue of the Pioneer cutting out (clipping?) at high volume, I turn it down and it comes right back on.

Suggestions on an alternator and battery for my Xb RS 3.0?

onionescion

Well I looked up regulated power supply for all you questioning my answer about caps and here it is!!!!!!!!!! for regulated power supplys
"Power supply that maintains a constant output voltage under changing load conditions". found here
www.sciencelobby.com/dictionary/r.html
So Like i said berfor a cap will not solve draws for certain amps !!!!!!!!!!!!!!
here is another one
"power supply provides a constant output regardless of voltage variations." found here
www.prosecuritywarehouse.com/techschool.html
The KEY word contant
Here is cap defined
"A device that stores electrical charges and can be used to maintain voltage levels in power lines and improve electrical-system efficiency." found here
www.dairynet.com/kids/gloss.html
"An electronic device which stores energy and releases it when needed. Also used to direct high frequency energy to tweeters. Rated in Farads." found here
www.precisionautosound.net/glossary.htm
So I would have to say a cap is a BIG BANDAID!!!!!!!!!!!!!!!
and does not help a regulated power supplied amp for a regulated power supply does the same thang as a cap!!!!!!!!!!!
If you want to inprove you cars electrical system replace the altenator battery and power and ground wires this is the best thing you can do.