What is a Stiffening Capacitor and Why Do I Need One?

We sell a LOT of capacitors in our store. We recommend them with every amp and sub sale. They make a difference in the quality of the bass and they help with that annoying dimming of the dash/head lights. But what are they, what do they do, and why do they help an audio install?

Definition

American Heritage Dictionary defines a capacitor as “an electric circuit element used to store charge temporarily, consisting in general of two metallic plates separated and insulated from each other by a dielectric.” Sounds almost like a battery doesn’t it? Well it is and it isn’t. A battery and a capacitor both store a charge. There are several key differences:

• A capacitor charges very quickly. A battery charges more slowly.
• A capacitor discharges very fast. A battery discharges more slowly.
• A capacitor stores a relatively small charge where a battery stores a tremendous amount of energy.

A battery’s main purpose is to start your car. It stores the current necessary to power your starter and turn your engine over. There is a lot of current delivered during several seconds of the crank cycle. But a battery is not capable of delivering quick bursts.

A capacitor does deliver those quick bursts. It also recovers (recharges) very quickly. But it does not have much reserve. It could never start a car. Or a lawn tractor for that matter!

How does this relate to car audio?

Music is a very dynamic medium. In every type of music there are quiet sections and very loud sections. When these loud passages occur, the amplifier needs more current to push the subs and speakers harder. It attempts to derive this power from the battery and charging system of the vehicle. Since a battery is not a very dynamic device (slow to discharge), the amp sometimes has trouble getting enough current to make the level of sound it is being asked to produce. This is where a capacitor comes in.

If you will recall, a capacitor charges and discharges very quickly. When there is a slow, quiet time in the music, the capacitor is charging. It stores this current until it is called for by the amplifier. Electricity will always take the path of least resistance. When a heavy bass note or a loud passage is called for the path of least resistance is the capacitor. The cap will instantly discharge the current necessary to make the note. And then it recharges just as quick.

During peak current demands, the amp is pulling its power from the cap instead of the charging system. The capacitor re-charges during less demanding periods. This process essentially smooths out the electrical system of the vehicle. The amp can do it’s job to the best of it’s ability making great bass and your headlight and dash lights don’t look like a disco.

The end result

When a quality capacitor is properly installed in your audio system the results can be significant. The key is getting the right capacitor and making sure it is installed properly. Take a trip down to your locally owned mobile electronics store. These guys know what they are doing and can give you the most out of your audio system.

Posted by Mitchell Schaffer

Owner of Mobile Edge in Lehighton, PA

Mobile Edge is a leading provide of quality aftermarket accessories and installations in Eastern Pennsylvania

www.MobileEdgeOnline.com

mitch@mobileedgeonline.com