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Rockford Fosgate Amp Doesn’t Need Connection To Car Battery

Rockford Fosgate has developed a simplified way to boost the speaker-level output of a factory or aftermarket radio with compact amps that don’t need power from a vehicle’s battery.

The PM100X1 mono amplifier uses patent-pending FreeLoad technology that not only takes in speaker-level audio signal for amplification but also stores unused audio-signal voltage in an internal capacitor bank to deliver higher output as needed. The amp can be mounted behind a door near the speaker that it amplifies.

The full-range 60Hz-20kHz amp, introduced at the company’s off-site venue during CES, ships in the summer at $399 MAP per pair.

The compact amp, which measures 1.3 by 3.9 by 3 inches, features a 2/4-ohm input switch to work optimally with 2- and 4-ohm radios. It delivers 50 watts of dynamic power in 4-ohm mode and 100 watts of dynamic power in 2-ohm mode.

FreeLoad presents the head unit’s amplifier circuit with a constant load, the company said, with a 2-ohm radio seeing a constant 2-ohm load and a 4-ohm radio seeing a constant 4-ohm load. “By doing this, the radio is producing consistent output power even as the signal’s sine wave is dropping back to zero,” the company said. “As the dynamic load drops, the internal storage recharges itself, ready for the next note,” the company said.  “It is this ‘free’ energy that charges the internal capacitor bank of the amplifier to produce higher output power when needed.”

At low volume, the amp uses the radio’s output for primary power up to the current limit of the radio’s amp circuit. Then at mid volume, the amp begins to draw some current from its internal capacitor bank to supplement its need, the company said. At high volume, the amp draws even more current from its capacitors.

The amp also comes with a selectable 60/80/100Hz high-pass filter for use, respectively, with 6×9-, 6.5-and 5.25- or 4-inch speakers.

A multipin connector connects the amp to the wires running to a speaker, the wires running to the radio’s speaker-level outputs,  and ground.

The amp is also “marinized” so it can be used in wet environments in boats and power-sports vehicles, the company said.