250-watt amplifier card module for an F6 Amplifier Mainframe System — for 4- or 8-ohm speakers
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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.
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- 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
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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.
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