I am looking to buy an amp for 2 12's in a box. They are each single coil and i was wondering if i should look for a 1 channel or 2 channel amp. Whats the difference between the 2 of them and what are my wiring options etc.
Thanks
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Peace
if they are DVC (dual voice coil), I would run them series parallel so you'd get a 4 ohm load and run them mono to a high power 2 channel amp. If they are SVC (single vc), then i'd run them in parallel for a 2 ohm load to a high current or Class D amp.
A mono amp, or AKA class D amp, is made only for subwoofers. It has more inherent noise than a stereo amp (AKA class A/B). The noise in the mono amp, however, is generally not noticeable in sub frequencies. The benefits are: they take less power to operate, because their efficiency is 90+% compared to a stereo amp whose efficiency is about 55%. That means there is less wasted power (from the car) going out as heat. A mono amp also means it has only one channel, so there is no stereo sound. Sub freqs are so low that you can't pinpoint direction the sound is coming from, so that works OK. Another benefit is price. For the same output power a mono amp would cost less than a class A/B amp, allowing that they are comparable in quality. The size is generally smaller as well, for one thing there is less room needed for heat sinks.
I would use a mono amp for subs for most average systems. For all the reasons I described. Higher-end systems may want to use the class A/B instead.
As far as voice coils go, it makes no difference to the amp whether they are DVC or SVC. The reason the dual coil subs exist is for wiring flexiblity, so that you can use any number of subs and arrive at the ohm load you want your amplifier to work with. Most people will run amps at a 2 ohm load rating to push the subs, while running the other speakers at 4 ohms. The speakers determine the ohm load, as in how they are wired on themselves (with dual coils), to each other (with multiple subs), and to the amplifier. If you currently have two subs each having a single 4 ohm voice coil, they can be parallel-wired to become a 2 ohm load.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.