The Zapco ST-500XM III 1-channel bass amplifier from the ST-X Class D Series is part of a series of four mono bass amplifiers of Class D, which can achieve a power output ranging from 400 watts RMS to 2,000 watts RMS. All Studio-XM amplifiers can also be connected to a single voice coil, allowing you to double their power at any time by simply linking them to another amplifier of the same model. The ST-500XM III 1-channel amplifier has a power output of 400 watts RMS at 1 ohm. On the connection front, there are settings for the crossover and bass boost. The ST-500XM III comes with a bass remote control included.

All new ST-XM III amplifiers have the following in common:

• Remote Control - All ST-X amplifiers come with a remote control that allows you to instantly change the bass output as needed.
• Input sensitivity controller (Gain) - Adjusts the sensitivity between 200 mV and over 5 volts.
• Mono Bridge Out and Bridge In - These allow the linking of two amplifiers (Strapping). When the Bridge Out RCA of the main amplifier is connected to the Bridge RCA In of the slave amplifier, the main amplifier (Out) takes priority in control.
• Low-pass crossover - All ST-XM amplifiers are designed as bass amplifiers and feature a full-fledged low-pass crossover that is adjustable from 40 to 180 Hz.
• Sub Sonic (HP) Filter - The reproduction of frequencies that are below those that one wants to hear wastes amplifier power. The Sub-Sonic filter helps to save this energy for the frequencies. More importantly, frequencies below the allowable range of the subwoofer can quickly destroy the subwoofer. This is especially important in enclosures with ports.
• Bass Boost Control - All ST-XM amplifiers feature a variable bass boost from 0 dB to 12 dB.
• Bass Frequency Controller - The bass reproduction of a subwoofer is different in every car, so a bass boost at 50 Hz can be great in one car but useless in another. With the ST-X Bass Frequency Controller, you can adjust the bass boost to any frequency between 30 Hz and 80 Hz, allowing it to be perfectly tuned to the music in the car.
• Phase controller - A bass enclosure that is oriented forward sounds different than when it is oriented backward. In both cases, it makes a difference when the phase of the subwoofer is changed. Furthermore, the ST-XM phase controller is variable from 0° to 180°, allowing you to set the phase relationship that works best in your car.

Features and Functions

• Single-channel Class D bass amplifier
• New Aluminum Housing
• Variable Input Gain Control
• Variable electronic crossover
• Variable Subsonic Filter
• Variable controls for bass boost
• Variable mitten frequency for bass boost
• Variable Phase Control
• "Buckleable for the use of two amplifiers on a single voice coil"
• Incl. bass remote control

• Power @ 1Ω: 1 x 400 Watts RMS (Maximum 500 Watts)
• THD @ Rated Power < 0.2% THD
• Power @ 2Ω: 1 x 300 Watts RMS
• Power @ 4Ω: 1 x 200 Watts RMS
• Signal-to-noise ratio > 85dB
• THD + Noise < 0.2%
• Efficiency > 85%
• Frequency response 10Hz to 200Hz ±1dB
• Input sensitivity .25v to 5v
• Dimensions in mm: 160(W) x 58(H) x 225(L)