FM 611 & FM

precision inside job: the FM 611X
precision inside job: the FM 611X

The FM 611 and FM 611X have thrilled thousands of listeners and won every possible accolade. After 18 years of continuous production they were finally be faded out. They have set standards the world over and are highly sought after.
The reason for their "retirement" has only to do with the fact that some of the newest technologies that have been used in the FM 115, the FM 411-MKII and the FM 1811 cannot be incorporated in the FM 611 and FM 611X - which makes it impossible to develop them further.
They will be replaced by a new power amplifier - the FM 711-MKII - where all the ameliorations have been incorporated. The FM 711-MKII provides even higher resolution, has more drive capability and higher power into complex (real-world loudspeaker) loads and this with an even smaller footprint.

The FM 611 and FM 611X have been - and will remain - amazing products. They sound amazing today and will obviously do so tomorrow.

This is not a lighthearted decision. It's more than nostalgia that we feel for these two power amplifiers that have cemented the unique reputation of FM ACOUSTICS.

A Few Specifications Of The FM 611X

Minimum Power Output:
per channel, both channels operating:
500 W peak into 8 Ohms
850 W peak into 4 Ohms
1400 W peak into 2 Ohms

250 W RMS into 8 Ohms
425 W RMS into 4 Ohms
700 W RMS into 2 Ohms

Max. Output Voltage: 140 V pp.

Max. Output Current:
Unlimited repetitive peak output current.
More than 30 A continuous per channel.
No output or DC fuses, absolutely no form of current-, voltage- or any other kind of limiting.

Distortion: Average distortion: <0,005% THD

Bandwidth including Input Filter:
Less than 3 Hz to 60 kHz;
if required, internally settable to any frequency between 1 kHz and 60 kHz (Low-Pass) and
1 Hz to 1 kHz (High-Pass).

Gain: 29dB

Risetime at Full Power: 3 us

Hum and Noise:
Below full power typically better than -115dB
Minimal unweighted:
better than -100 dB

Proprietary electronically balanced discrete enhanced class A circuitry, non-polarized, floating ground, non- inverting or inverting mode. Optimal performance with either balanced or unbalanced (single-ended) sources. Unbalanced sources are automatically balanced right at the input of the FM 611X.

Input Sensitivity:
1,6 V RMS for full output
Input Impedance:
At all level settings from balanced and unbalanced sources: 40 kOhms

Input Stage Common Mode Rejection:
90 dB typically, better than 80 dB at 50 Hz, even better at other frequencies.

Maximum Input Level:
+20 dBm (7,75 V RMS)

Load Impedance:
No minimum impedance. The amplifier is designed for 1 Ohm to 10'000 Ohm systems. It can drive any speaker impedance (even below 1 Ohm) with dynamic (music) signals without any limiting, compression or other negative effects on the audio signal. Despite this, the amplifier is fully protected against short circuits, open circuits and all other adverse conditions via a unique onboard computer that continuously surveys all important parameters.