FM 800A & FM 600A

The sturdy black FM 800A
The sturdy black FM 800A

FM 600A & FM 800A were the first power amplifiers manufactured by FM ACOUSTICS.

The FM 800A was the result of a decision to build a robust power amplifier with safeguarding, better cooling system, higher output power and improved control of the speaker diaphraghms (all weaknesses of the design that at that time was the 'State of the Art' in power amplification). It was designed for our own use in room analyses.
Of the original only four pieces were built.

  • One day an FM 800A's was loaned to musician friends because their amplifier had broken down. A week later, enquiring about the return of the amplifier, the answer was straightforward: "we'll never return the FM 800A because it sounds fantastic, so much better than any other amplifier..." (it must be remembered that at that time, it was generally believed that "all transistor amps with similar power and specs sound exactly the same").
  • This "much better sound" provoked our scientists to start a massive research to find the reasons for the audible superiority over other power amplifiers. Over the years, this self-financed R&D has provided a wealth of know-how which allows us to better understand certain interactions and circuit behaviour under dynamic conditions. It is the application of this know-how that makes FM ACOUSTICS products unique.
  • The FM 600A was introduced in 1977 when a power amplifier for professional applications with somewhat lower power was requested. In its three versions it was manufactured for over 20 years.
  • In the late 70ies, speakers with lower impedances came on the market and consequently more drive capability of the power amplifier was required. Specially for such applications, the 'LI' (Low Impedance) versions were introduced. FM ACOUSTICS were the only high-power amplifiers remaining absolutely stable and transparent while being able to drive impedances of 2 Ohms with unprecedented quality. They became a wide success.
  • When speaker impedances dropped further, even more drive capability was required. The 'ULI' (Ultra Low Impedance) versions were introduced.
  • It has been remarked that no other brand ever came close to these flagships used in studios, with musicians on stage and in private homes. Over 90% of all FM 600A's and FM 800A's that were manufactured are still in regular use today, indeed a rather rare occurence in audio. FM ACOUSTICS continuously invests in a tremendous parts stock and has kept available these parts over all these years, so even today these amplifiers can be kept functioning perfectly.
  • Even complete restorations of products are performed. While this is a loss-making endeavour, we keep providing this service to our clients. After all, these amplifiers are part of our heritage.



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8132 Egg b. Zurich



Phone:  + 41-44-7257777

Fax:     + 41-44-7257790


Last updated : 23.04.2024