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Damping Factor

When you look at an amplifier’s specifications you may come across one that says “Damping Factor”. The damping factor describes the ability of the amplifier to control the movement of a speaker, more specifically, unwanted movement. This is especially important for lower frequency speakers such as car subwoofers.  Damping factor can be looked at from many different angles and several factors affect the overall damping factor in a system.

In a simple sense, the damping factor tells you how well an amplifier can control a speaker system. The larger the number associated with damping factor the better an amplifier is at controlling speakers. Anything above 100 tends to be very good while below 30 is poor. Most aftermarket car audio amplifiers to date won’t have such poor damping factor specifications to the point where it would become a concern for the average listener if they follow specs. This means that if you’re trying to get the best sound possible you need to look for a higher damping factor, assuming everything else is equal.  Below I will get slightly more technical, so the above information is very simplified.

Most manufactures do not specify damping factor accurately in their specification charts. An accurate damping factor will look something like this: Damping Factor = 100 at 4 Ohms. Rarely is the impedance (ohms) listed. Damping factor is the speaker systems final impedance (load impedance) divided by the amplifiers output impedance. So if you have one speaker at a perfect 4 ohms impedance and divide it by the amplifiers output impedance, let’s say 0.4, you get a damping factor of 100 (4.0 / 0.04 = 100). If your final impedance is 1.0 ohms and the amplifiers output impedance is 0.04 your damping factor becomes 25 (1.0 / 0.04 = 25). Using this formula, as long as you know the amplifiers output impedance and your speaker systems final impedance, you can calculate the damping factor. This is why it is important for the manufacture to list what impedance they list their damping factor at for the most accurate number. However, using the formula you can find out if you have most of the other information.

Let’s throw a monkey wrench into the mix. In the real world, a speaker’s impedance is affected by everything in the system. A  car audio speaker will fluctuate anywhere from 1 ohm to even 30 or 40 ohms while it is operating. So if damping factor is based off of the speaker’s impedance but it’s always jumping up and down then that means the damping factor can’t be a single number. Damping factor is a major simplification of what is actually going on but it is still important! If everything is relatively equal you would be able to notice the difference between a damping factor of 100 and 25. While this should not be your go-to to find the best quality in an amplifier, if all the other specs are closely matched you can look at it to help make a final decision. Knowing all the specifications and what they mean can really help put everything into perspective when selecting an amplifier and speaker combination. Remember, it all comes down to what sounds best to YOUR ears.

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Staff writers at Sonic Electronix are experts in their field. In addition to a complete in-house training program, these experts typically have many years of hands-on experience in their specialty. Some come from car audio installer backgrounds, while others come with extensive retail experience.
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