by Brian Smith
Back in February of 1997, we reviewed a little amp called the D100HC. At that time, we declared that it was the best subwoofer amp for an automobile that money could buy. It was small, efficient, and it would make lots of power. However, time and the pursuit of bass stands still for no man. Enter the D300HC, another class D mono-block subwoofer amp from MMATS. The D300HC features an internal crossover with variable cutoff frequency, huge gold-plated power connections, and enough raw power to make your neighbors move away.

This powerhouse is designed to push 1748 watts into a 2-ohm reactive load. The best thing about the D300HC is that you don’t need a train-load of batteries to power it. While it is capable of drawing around 180 amps at full output, most of that power is making it to your speakers as opposed to a max of about 50 percent seen in most other designs. On the down side, turn on/off noises (48.1 dB SPL, 44 dB SPL, respectively) and signal-to-noise measurements were a bit higher than usual (–86 dB) — but if you need 1700 watts, what’s a little pop? The amp also utilizes a protection circuit that limits current if you try to run it below its rated 2-ohm impedance.

Connections & Adjustments
Connections to the D300HC include RCA inputs, captive-style power connectors that accept up to 4-gauge wire, and 8-gauge speaker connections that are housed in a modular plug. Adjustments consist of input sensitivity and crossover cutoff frequency — you couldn’t ask for a more straightforward design.

Big power in a small chassis that runs cool — an installer’s dream come true. We usually use a small fan when power testing amps to keep them as cool as possible, but during this hogs ride on our test bench, the fan spent more time on the load resistors than the D300HC. There’s only one thing to watch out for, don’t let the speaker outputs come into contact with ground while the amp is powered up. There’s somewhere in the neighborhood of 40-VDC between the outputs and the amps chassis — blue flashes and the smell of burning ozone is not a good way to start the day.

The manual for the D300HC, which consists of three stapled pages, and includes wiring diagrams, power ratings, and a big warning about that 40VDC, was not as precise as we would have liked to have seen.
Price & Contact: $999; 561-848-7578;