OSD Audio - SMP300 Mono Class D Subwoofer Amplifier, 500W Peak, Rack Mountable, Auto Sensing - Black
Model: SMP-300S
SKU: 13103329
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The SMP300 is a Class D mono subwoofer amplifier delivering up to 500W peak power at 4 ohms and 250W continuous RMS, built for passive subwoofers such as in-wall models that require external power. At only 3 inches high it fits inside any equipment rack or cabinet and includes 1U rack mounting hardware. A front-panel variable low-pass filter adjusts from 35Hz to 180Hz to control the overlap between the subwoofer and main speakers, while variable phase control from 0 to 180 degrees fine-tunes alignment so bass reinforces rather than cancels. Front-panel volume completes the setup controls. Multiple connection options include LFE input plus line-level and speaker-level inputs, covering both newer receivers and older source equipment. Auto-sensing shuts the amplifier down when no signal is detected, and the power supply is switchable between 120V and 230V. Frequency response spans 20Hz to 160Hz within 1dB with a 95dB signal-to-noise ratio. ETL and CE certified with a 2-year warranty.
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Class D amplification supplies 250W RMS at 4 ohms and 150W RMS at 8 ohms with 500W peak output, providing continuous stable power for in-wall and stand-alone passive subwoofers. The extra headroom over smaller sub amps keeps bass accurate during demanding movie soundtracks rather than compressing at peaks.
A front-panel variable low-pass filter sets the subwoofer's upper frequency limit anywhere from 35Hz to 180Hz. Controlling the overlap between the subwoofer's upper range and the main speakers' lower range produces balanced, seamless sound instead of a doubled or hollow midbass region.
Variable phase adjustment from 0 to 180 degrees aligns subwoofer output with the main speakers so the two reinforce each other. Front-panel volume sets the amount of low-frequency effect. Both controls are accessible without pulling the unit from the rack, which speeds up room tuning.
Three input types cover the full range of source equipment: a dedicated LFE input for modern AV receivers, line-level RCA for pre-amplified sources and speaker-level inputs for older receivers without a subwoofer output. One amplifier works across new and legacy systems.
At 16.25 by 3 by 9.25 inches and 7 pounds, the amplifier occupies a single rack space with mounts included, or sits in a cabinet. Auto-sensing shuts the unit down when no signal is present. Dual voltage switchable 120V/230V, 95dB signal-to-noise, 20Hz to 160Hz response. ETL and CE certified, 2-year warranty.