JL Audio XD400/4v2 (Open Box, Great)

This potent 4-Channel amplifier employs JL Audio's high-speed NexD™ switching design to achieve unprecedented efficiency and amazing power output in an ultra-compact chassis. Don't let the small size fool you, though... this amplifier is capable of serious power, delivering a full 400W of continuous total power into a 2 ohm load (14.4V, 1% THD). Targeted specifically for an audiophile-grade four satellite system, the XD400/4v2 includes a variable mode low-pass/high-pass filter with a continuously variable cutoff frequency selection from 50-500 Hz. The XD400/4v2 also features the v2 Spec feature set, which consists of automatic turn-on capability (via signal sensing or DC-offset sensing), and a dual-range differential balanced input section able to handle a wide range of input voltage levels. With the addition of an HD-RLC remote level control (sold separately), you can control the volume of one or both channel pairs of the XD400/4v2 from the front of the vehicle. This amplifier features a black powder-coat finish and a gasketed, brushed aluminum cover for the controls.

Advanced Rollback Protection

JL Audio's signature Advanced Thermal Rollback protection system eliminates annoying thermal shutdown events to keep the music playing, even under the most demanding conditions. Should the amplifier reach an unsafe operating temperature, a special circuit rolls back peak power output, without changing gain, until the amplifier cools down to a safe operating temperature. The red "Thermal" LED will light to indicate this condition has been reached. Once the amplifier cools down, the circuit restores full peak power output and the red "Thermal" indicator reverts to its normal state. The operation of Advanced Rollback Protection is inaudible in most cases.

NexD Switching Technology

From the same minds that gave us the technology found in the 'Slash' amplifiers, JL Audio has taken the simple fixed PWM design approach and enhanced it with a very high switching frequency. Full-range NexD™ amplifiers and channels feature a variable, ultra-high speed version of the NexD™ technology (switching at well over 400 kHz). In these designs, a self-oscillating modulator with "feed-forward" sends information about the instantaneous power supply voltage to the modulator, combining this with the input signal to cancel out any distortion due to supply voltage fluctuation. This reduces distortion prior to applying feedback, simplifying the overall feedback loop design.