250-watt amplifier card module for an F6 Amplifier Mainframe System — for 4- or 8-ohm speakers
Our take on the Atlas FM250-4 by Crutchfield's Buck Pomerantz
Amplifier for the F6-MF system
The Atlas Sound FM250-4 amplifier module can provide up to 250 watts of power for your commercial speaker installation, playing music and speech clearly and loudly enough for all to hear. Each FM250-4 fits into one of the six amplifier card slots of an F6-MF mainframe chassis, connecting internally to the master unit's power supply and inputs.
Onboard adjustments and indicators
A Dip switch lets you set the amp's input sensitivity to maximize the signal over background noise, and engage a high-pass filter to clear any low rumble out of the mix. Rear-panel status LEDs, like the ones on the F6-MF's front panel, let you know how the amp's behaving.
Get a free system design
- amplifier card module for Atlas Sound F6-MF mainframe system
- designed for 4- or 8-ohm speakers
- 250 watts (continuous) x 1 at 4 ohms
- 125 watts (continuous) x 1 at 8 ohms
- selectable high-pass filter (100 Hz at 12 dB/octave)
- selectable input sensitivity (1 or 2 volt)
- fixed subsonic filter (30 Hz)
- dimensions: 1-1/2"W x 3-7/16"H x 10-7/16"D
- weight: 12.8 oz.
- warranty: 3 years
- Our 60-day money-back guarantee
What's in the Box:
- 4/8 Ohm amplifier module
Overview: The Atlas FM250-4 is an amplifier module is designed to work specifically with the Atlas F6-MF power rack, which can hold up to 6 modules. The FM250-4 module can output 250 watts, features a defeatable Limiter and a High-Pass Filter, and can power both 4 and 8 ohm speakers. It's Class-D amp technology is designed to be 90% efficient, allowing the amp to run cooler and consume less energy than conventional amplifiers.
Installation: The FM250-4 module includes a multi-terminal strip on the rear of the PC board that lines up with a contact slot on the F6-MF power rack. The card is then secured in place with 2 front panel screws. Signal input to the card is through the rack, which has six 3-pin Euroblock connectors on the back of it, along with Level dials for each channel. The front of the module includes a 2-pin Euroblock connector for connecting a 4 Ω or 8 Ω speaker load. If powering speakers in a 70.7 volt system, the FM250-70 module can be used. This installs into the F6-MF power rack in the same manner and provides the same power output for running 70 volt speakers.
Settings: The FM250-4 module includes a 3-setting DIP switch on the rear of the module which includes:
- DIP Switch 1: This switch changes the Input Sensitivity
- On: Sensitivity is 1 volt
- Off: Sensitivity is 2 volts
- DIP Switches 2&3: Activates the High-Pass Filter
- On: When both switches are On, a 100 Hz / 12 dB per octave High-Pass Filter is engaged.
- Off: Both switches Off allows a full-bandwidth signal to pass
Status Indicators: The front of the module includes 4 Status LEDs for the following:
- Ready: Will light green when the FM250-4 power module is installed and the F6-MF is powered on.
- Signal: Will light green when the FM250-4 amp module's output signal produces a minimum 1 watt signal.
- Limit: If the FM250-4 amp module's function switch is set to Limit, the the LED will light yellow acting as a maximum level indicator. If the amp module's Limit function is off, the LED acts as a Clip indicator. Also, under low impedance loads, the LED serves as a current Limit indicator.
- Protect: Will light red to indicate a speaker short, too high internal temperature, or too low of a speaker impedance.
- Output Power, Burst power @ 1 kHz, ultra fast
recovery power supply:
- 1 Channel: 150 Watts
- 2 Channels: 140 Watts each
- 6 Channels: 125 Watts each
- 1 Channel: 300 Watts
- 2 Channels: 280 Watts each
- 6 Channels: 250 Watts each
- Continuous Power @ 1 kHz
- 1 Channel: 135 Watts
- 2 Channels: 125 Watts each
- 6 Channels: 95 Watts each
- 1 Channel: 270 Watts
- 2 Channels: 250 Watts each
- 6 Channels: 170 Watts each
- Frequency Response: 30 Hz - 20 kHz
- Signal to Noise Ratio: -90 dB below rated output
- Dimensions: Width - 1.5", Height - 3.4", Depth - 10.4"
- Weight: 0.8 lbs.
Our Product Research Team
At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.