Tag: ohm

Damping Factor

The Damping Factor of Your Amplifier Tells You How Well it Controls The Movement of Your Speakers

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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What is the Difference Between 2 and 4 Ohms?

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Ohms are the measure of resistance to the flow of electricity in an electric circuit. Think of it like a freeway, the more cars congesting the freeway, the slower everyone will move due to traffic. Electricity, like the cars, can be slowed down in the circuit due to higher resistance.  The higher the ohm value, the more difficult it is for current to flow through a circuit. Likewise, the lower the value, the easier it is for current to flow. Based on this, is there any other differences between the most common 2 and 4 ohm impedances?

Certain amplifiers are designed to power subwoofers at different impedances (ohms). For example, a 2 ohm rated amplifier will power a 2 ohm subwoofer, so long as the woofers “final impedance (ohms)” is 2. You can connect multiple subwoofers together and run them off an amplifier, so long as their final impedance is equal to the amplifiers impedance. We cover this in a different article. If you have 100 watts at 2 ohms, and 100 watts at 4 ohms, is there a difference? The answer is subjective, you will hear people say there is a sound difference, and some say there isn’t. It depends on how efficient the amplifier runs at the specified ohm level, as well as the speaker itself.

If you get technical, the different resistance values of a speaker will change the sound slightly, assuming wattage is the same. A lower impedance subwoofer has a voice coil with fewer windings, meaning less weight. A higher impedance subwoofer will have more coil windings, meaning more weight. It has more windings to counter act the resistance, so it’s like adding more lanes to the freeway to ease up traffic. This slight difference in weight will produce a slight sound quality difference. At 2 ohms you tend to have more projection of sound (louder), which causes poorer sound quality. At 4 ohms you will have less mid bass frequencies then at 2 ohms; however the sound quality is slightly improved.

If you’re not an audiophile, does this matter? Honestly, no it does not. Do not let this be a make or break when looking for sound system components. Two of the same subwoofers, just with different impedances, will produce almost the same sound if they are run at the same wattage. The difference in sound is so slight that it has little impact, especially when dealing with subwoofers, that you likely can’t tell the difference.

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What are the Differences Between Single and Dual Voice Coil Subwoofers?

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You’re shopping for subwoofers and you see two identical looking woofers. You read the specifications on the label and notice they are the same for both car subwoofers. The price is slightly different and the model numbers are slightly different, but everything else is the same! But wait, you turn them over and one says “Single 4 Ohm” and the other says “Dual 4 Ohm”. This is no deception, your eyes don’t lie. Before you bag one up and take it home, do you know the difference between a Single and Dual voice coil subwoofer?

First of all, what is a voice coil? The voice coil in a subwoofer is a coil of wire wrapped around a cylinder called the former, which accepts the amplifiers current. Current from the amplifier causes the coil to react with the stationary magnet, moving the former up or down. The former is attached to the speaker cone which produces changes in air pressure when moved, producing sound.

A single voice coil (SCV) is one length of wire wrapped around the former. A dual voice coil (DVC) has 2 coils of wire wrapped around the former. A single voice coil subwoofer will have a positive and negative terminal, while a dual voice coil subwoofer will have 2 positive and 2 negative terminals, one for each coil. The price of a DVC subwoofer will usually be slightly higher than its SVC brethren due to the extra coil. There is no performance advantage between the two types of voice coils, so why bother?

The advantage of a DVC subwoofer over the SVC subwoofer is your available wiring options and flexibility. Single voice coil subwoofers can only be wired at the ohm level specified, for example 4 ohm. A dual voice coil will say 4 ohm, but it will actually wire to 2 ohm or 8 ohm. That last sentence alone tends to blow the minds of many, you are not alone. The ohm level needs to match up with the ohm level your amplifier can handle. A DVC woofer has 2 wiring options while the SVC has only one option.

When everything is all said and done, the only real difference between a single and dual voice coil subwoofer is the number of coils, which means a greater wiring flexibility. The power handling, frequency response, box volume specifications, etc. will remain the same for both types of woofers (except in rare cases). Feel free to use the Sonic Electronix subwoofer wiring diagram to help you configure the right subwoofers.

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