Car Stereos: capacitor or battery/capacitor cell combination, power supply voltage, watts rms

Question
Brian i will be running 2 amps in my car. One will be a 4 channel amp a Powerbass ASA 400.4X rated at 400 watts rms. I will have this amp set at the 4ohm, 50rms x 4 setting for my door speakers. They are rated at 50rms.  The second amp is a Powerbass ASA 1500.1DX mono amp rated at 1500rms which will be set at 4ohm, 325rms x 1. The sub is rated at 350rms. Can i use one 2 farad capacitor for both amps or does each amp needs it's own capacitor. I was thinking about getting a battery/capacitor cell combination. A Soundstream S Cell300 300 amp battery/capacitor.  What would be the best way to go. And will this replace the car battery.

Answer
Hi George,

In my opinion, the system you're describing really doesn't need any particular upgrade from the stock charging system.  You can add a capacitor, if you like; and it certainly won't hurt anything; but I don't see any reason to add anything larger than a single 1-farad capacitor, for both amplifiers--you don't need to put a separate cap on each amp.  A simple, but effective, wiring method is to use the capacitor as a distribution block:  Connect a the main power wire to the capacitor's power terminal, then separate power wires from the same terminal to each amplifier.  

Many people tend to expect too much from a capacitor in an audio system.  A power supply capacitor isn't meant to reduce the overall strain on the vehicle's alternator or charging system, and it won't make a significant difference in volume or bass output.  It might make a subtle difference in the sound produced by your 4-channel amp, particularly in the transients: a capacitor can help the amplifier's "headroom" by maintaining a steady power supply voltage when the amplifier requires a brief, sudden burst of current.  However, you won't really gain anything by using a larger cap than you need--in fact, larger capacitors tend to have a higher internal resistance, so a "super" cap might not help you as much as smaller cap.    

If you do purchase one of the hybrid "cap-cells" like the SCELL300, it's not meant to replace the stock battery.  Even the biggest capacitor doesn't store nearly as much power as a typical automotive battery.

Hope this helps!

Brian