Deciding which subwoofers to buy depends on the amp you are using and the number of subwoofers you are going to use. The dual voice coil subwoofer can have its coils wired in series to produce an 8 ohm load, or in parallel to produce a 2 ohm load.You want to choose a combination of subwoofers that will let you wire the voice coils together to an impedance that will allow the amp to make the power you want. We have the option of two different fictional subwoofers, each rated for 750 watts of continuous power handling. To complete this fictional example, we have an amplifier that will produce 400 watts into a 4 ohm load and 700 watts into a 2 ohm load.With 20 V applied to our voice coil, let’s say we have a 4 ohm impedance on this coil.
We don’t need to worry about the fact that this is an alternating current signal – we will examine this at a single point in time.This low impedance, combined with the increased voltage of the audio signal in the amplifier, causes relatively large amounts of current to flow through the voice coil of the speaker.This current flow causes a magnetic field and, subsequently, the voice coil moves toward or away from the magnetic field created by the stationary magnet on the speaker.We could wire all the coils in series to present the amp with a 16 ohm load – but that’s not going to happen.
We could wire the voice coils on each subwoofer in series, then parallel the pair of subwoofers to get a 4 ohm load. If we use a pair of single voice coil subwoofers, however, and wire the subs in parallel, we get a 2 ohm load. Do not wire one dual voice coil subs in series and one in parallel before connecting the subs together in parallel.In this example, we have the same electronic equipment, but the vehicle is a large SUV.