SFB-1500D

The SFB-1500D is a compact Class D monoblock rated at 1500W RMS at 1 ohm, 1200W at 2 ohms, and 650W at 4 ohms. Sundown notes it measures up to 1750W RMS at 1 ohm on the bench, which is consistent with how the brand rates the rest of its amplifiers.

The SFB full-bridge platform is about power per cubic inch. This one measures 7.25 by 6.75 by 2.50 inches, so it mounts under a seat or on a small rack while feeding a full-size subwoofer. A dual MOS-FET PWM power supply handles current delivery, and a three-speed temperature-activated cooling fan steps up as the amp warms, keeping output steady during long, loud playback instead of tripping thermal protection.

Controls cover both ends of the range. The variable 12 dB per octave low pass filter reaches 80 Hz to 20 kHz and the high pass filter covers 15 Hz to 1 kHz, so the amp works for subwoofer duty or a full-range speaker load. Variable bass boost adds 0 to 12 dB. Signal to noise ratio is 100 dB.

A four-way protection circuit watches thermal, voltage, speaker short, and DC-offset conditions. The wired remote control includes a clipping indicator, so level changes from the seat come with feedback on where clean power ends.

Working voltage is 10.5V to 15.5V DC with a 140A recommended fuse.