Fosi Audio M03 Subwoofer amplifier

Highlights:

• Compact mono Class-D amplifier for passive subwoofers and speakers
• SUB/PBTL switch for subwoofer or full-range operation
• Adjustable low-pass filter with crossover frequency from 20 to 200 Hz
• Up to 100 W output power at 3 Ohms
• RCA input and speaker terminals
• Supports speaker impedances from 2 to 8 Ohms
• Integrated on/off function in the volume control
• Supplied with 19V power supply

Compact amplifier for a passive subwoofer or speaker:

Fosi Audio M04 is a small and versatile mono Class-D amplifier that makes it easy to add extra bass to your audio system or power a single passive speaker. With its built-in SUB/PBTL switch, the amplifier can be used for both subwoofer operation and conventional full-range playback. This provides several possibilities in a compact design that is easy to accommodate alongside your existing equipment.

In SUB mode, the M04 works as a dedicated subwoofer amplifier with an active low-pass filter. The crossover frequency can be adjusted from 20 to 200 Hz, allowing you to match the bass response to your other speakers. This makes the amplifier suitable for passive in-wall subwoofers, for example, or an existing passive subwoofer that requires a separate amplifier.

Easily switch between subwoofer and full-range operation:

The switch on the Fosi Audio M04 lets you choose how the amplifier operates. In SUB mode, low frequencies are sent to the connected passive subwoofer, while PBTL mode provides full-range playback with a frequency range from 20 Hz to 20 kHz. This means the M04 can also be used to power a single passive speaker, such as an additional speaker in a separate audio zone.

The amplifier features an RCA input that can be connected to a suitable line-level output on a preamplifier, stereo amplifier or AV receiver. This makes the M04 a practical solution for expanding an existing stereo system with a passive subwoofer. Operation is straightforward, with the on/off function integrated directly into the volume control.

Flexible power supply and compact dimensions:

Fosi Audio M04 supports a DC supply voltage from 12 to 24V and comes with a 19V power supply in this version. The included adapter allows you to start using the amplifier without purchasing a separate power supply. If higher output power is required, a compatible 24V power supply can be used, as the maximum output of 100 W at 3 Ohms is specified at the highest supply voltage.

The compact enclosure makes the M04 easy to integrate into an existing audio system, even where space is limited. Weighing just 175 grams and featuring a straightforward design with an RCA input, speaker terminals and control knobs, it offers a simple solution for powering a passive subwoofer or a single speaker.

Specifications:

• Type: Mono Class-D amplifier
• Operating modes: SUB / PBTL
• Maximum output power: 100 W at 3 Ohms
• Speaker impedance: 2-8 Ohms
• Input: RCA
• Output: Speaker terminals
• Input sensitivity: 600 mV
• Frequency response: 20 Hz - 20 kHz (±3 dB)
• Adjustable crossover frequency: 20-200 Hz (SUB)
• THD: = 0.02% (1 kHz, 1 W)
• Signal-to-noise ratio: = 102 dB
• Power supply: DC 12-24V
• Included power supply: 19V
• Dimensions (H x W x D): 10.3 x 5.7 x 4.3 cm including knobs
• Weight: 175 g
• Included: 19V power supply, AC cable and user manual