If your headlights dim, your CD skips a beat, and your audio system distorts, your electrical system may not be up to par. It's likely your alternator is having a difficult time maintaining a running voltage of 14 volts, as your battery is not capable of holding the system voltage above 12 volts. This leaves you with a fluctuation of two or more volts, all the while killing your listening experience.
You need help and audio capacitors may just be the answer. The following tutorial will guide you through the importance of capacitors, how they work, and where and when to use them.
What are they?
Stiffening capacitors, often called "load leveling" devices, are becoming more and more common these days in the world of car audio, especially in high-end installations. These are commonly used as buffers between the battery and the amplifiers or electronic hardware. But the value of these is often misunderstood, the how and when to use them misconceived. For this, we will walk you through the ins and outs of capacitor technology.
In order to find our test subjects, we conducted a search on the World Wide Web. We found a plethora of sizes and styles of capacitors available from a variety of audio manufacturers. However, as our objective was to discover different technologies in the capacitance field and the workings behind them, the field narrowed quickly. We decided on the following four leaders in capacitor technology: Alumapro, Lightning Audio, Phoenix Gold, and Xstatic.
So the question remains: do they really have an effect on an audio system? We think you'll be surprised with our results.
What is a capacitor?
Like a battery, a capacitor is an energy storage device. While a battery stores and releases energy through an electro-chemical reaction, a capacitor stores energy via an electrostatic charge. As we will see, this difference in technology is the reason why capacitors can be helpful in an audio system.
How do capacitors work?
First we will start you off with a little tech jargon (repeat this to your friends, they will be amazed). The energy stored in a capacitor is measured in Joules, with the total energy stored = 11/42CV2 (see diagram below). This energy increases with the square of the voltage times the capacitance in farads.
In the simplest form, capacitors have two plates, each connected to a terminal separated by an insulator. When a cap is connected to a battery, the negative plate gains electrons from the battery while the positive plate loses electrons. This charge is called an electrostatic field. When the capacitor is discharged, the reverse happens. The capacitance increases with the size of the plates. As well, the capacitance will increase inversely with the distance between them.
Because the capacitance increases with surface area, large value capacitors must have a large surface area and a very short distance between the plates. In the past, a capacitance of 1 farad seemed huge. These were called aluminum electrolytic and were constructed of large rolls of aluminum foil with an electrolyte between them. The foil was coated with an oxide to increase the surface area. To further increase the surface area, the foil was then rolled. This is why most capacitors are cylindrical.
Electrochemical Double Layer CapacitorsIn recent years we've seen a giant leap in capacitance technology, also known as Electrochemical Double Layer Capacitors, or EDLC for short. EDLC capacitors have energy densities that are typically greater than 300 times that of the largest conventional capacitors.