Power Capacitors
Stiffening capacitors can help your amplifiers deliver up to 50% more output on those demanding peak bass notes. Most automotive alternator/battery systems simply lack the ability to produce large amounts of instantaneous power. This is exactly the type of power that car audio amplifiers crave. Adding a stiffening capacitor to your system can add tremendous bass punch and improve transient response.

Stiffening capacitors FAQ's

What is a stiffening capacitor?
Computer grade power caps (also known as stiffening capacitors) store energy and then very quickly release it on demand to your power amplifier(s). The term stiffening capacitor as a generic term refers to any large capacitor (100,000 Microfarad and larger) placed in parallel with an amplifier and battery.

How does it work?
A stiffening capacitor charges like a battery. But unlike a battery the stiffening capacitor is designed to quickly release power on demand. This quick burst of power aids your amplifier in producing deep bass notes when it needs it. In between deep bass notes your battery and alternator re-charge the cap allowing it to be ready for the next deep bass note. This battery voltage assistance reduces voltage induced amplifier clipping, increases transient response, increases bass punch, and increases amplifier life.

Where should my capacitor be mounted?
Stiffening capacitors should be mounted as close to the amplifier as possible.
One of the other benefits of stiffening capacitors is the ability to reduce line loss. Line loss is created by the power cable itself. Long runs of power cable associated with mounting amplifiers in automotive trunks creates line loss, especially during deep bass notes. Stiffening capacitors help maintain appropriate system voltages at the amplifier.

What size capacitor do I need?
As a general rule we recommend 100,000 Microfarad (.1 Farad) per 100 watts of amplifier power, or 1 Farad per 1000 Watts. Use the simple chart below to determine what size capacitor you need.

Total Amplifier Power Capacitor needed
Up To 500 Watts .50 Farad
500-1000 Watts 1.0 Farad
1000-1500 Watts 1.5 Farad
2000 Watts 2 Farad

Dont forget this is RMS value not MAX POWER value

Can I use multiple caps?
Yes, Capacitors add in value when wired in parallel. Example: Two 1 Farad capacitors wired in parallel sum to 2 Farad. This is the perfect size for a competition system with up to 2000 Watts of trunk mounted amplifiers.

What voltage capacitor do I need?
Automotive battery charging systems typically vary between as low as 12VDC up to as high as 14.5VDC with the average alternator output at 13.8VDC. Generally speaking stiffening capacitors these days are rated at 20VDC average and 24VDC surge. We do not recommend using capacitors rated below 16VDC but higher is always better.

Do stiffening capacitors require special handling?
Handle stiffening capacitors as you would a charged battery. The main thing you need to worry about is initial installation charging and discharging. Most capacitors are supplied with a charging/discharging resistor or lamp. Capacitors draw a very large amount of current during installation. DO NOT attempt to connect 12VDC directly to the terminals or arching and permanent terminal damage will occur.

Utilize a charging resistor or lamp in series with the cap and follow the instructions supplied with your capacitor to slowly energize the capacitor and eliminate arching. NEVER short the leads of a stiffening capacitor. When un-installing a capacitor remove the source voltage then use the same resistor or lamp to slowly de-energize it.

Anything else I should know?
Yes, ALWAYS install an appropriate fuse or circuit breaker between your amplifier/capacitor in the boot and your battery power source