FM 133 & FM 233 Harmonic Linearizers

Wherever they are put into action, the unique Harmonic Linearizers amaze...
Wherever they are put into action, the unique Harmonic Linearizers amaze...

 FM ACOUSTICS does not need superlatives in product descriptions but experts who have worked with the FM 133 & FM 233 Linearizers all reacted the same:
"...these are truly amazing..."




  • "This is a revolution, a true breakthrough".
  • "This is the most spectacular improvement of music - in fact of any audio source - in the last 40 years".
  • "A tremendous achievement"
  • "The most important component of a quality Audio system"


Detailed information on the Harmonic Linearizers.
Adobe Acrobat Document 428.5 KB

The dream

Whatever the audio system, its reproduction is only as good as the source.

Today, the major limitation in audio reproduction is no longer so much the quality of reproducing equipment. The most limiting factor are the many mediocre sounding sources, be they CD's, DVD's, downloads, LP's, Tapes, Shellacs etc.
There has been a profound lack of equipment that allows the restitution and improvement of music sources.


Until now...

The dream and ultimate goal of musicians, engineers and music aficionados has finally become reality: be able to correct errors and weaknesses in music recordings and Film/movie sound without influencing the original signal!

  • It is quite an experience to:
    be able to improve cheaper pressing of LP's to the level of - and sometimes better than - the best (and most valuable...) early stamper pressings!
  • To make a standard pressing sound equal to - or even better than - the best of expensive half-speed masters and special audiophile pressings!
  • To be able to improve re-issues while avoiding the noise and sometimes poor pressing quality of certain rare originals!
  • To linearize the reproduction of movie sound and achieve much improved clarity and realism!
  • To be able to create one's own masters (CD's, DVD's etc.) improving the original!

Massive improvements


The FM 133 & FM 233 Harmonic Linearizers allow precise orrection and linearization of non-optimal recordings. They do this in an absolutely unique way. For the first time bad resonances, colouration, noise, obnoxious sound and other limitations are improved without affecting the audio signal. While the characteristics and transparency of the original signal is kept pristine, attenuated parts of the music spectrum can be strengthened.

The method of operation is rather intriguing as the entire audio signal takes a direct path from input to output. The improvement is achieved by a unique additive/subtractive Linearizer bank that corrects aberrations. Using just five controls, any frequency (or group of frequencies) in the entire audio band can be optimized without negative influence inflicted on the original audio signal. Furthermore, the signal always remains purely in the analogue domain.

When looking at the front panel one could be reminded of an equalizer. However, the Harmonic Linearizer's mode of operation is different and avoids all limitations. The FM 133 & FM 233 are not used like an equalizer as every control is dynamically interacting with the others in a unique linear multi-parameter process. There is no ripple in the pass band and no phase shift/discontinuity (both of which are known issues of equalizers).

Massive improvements in the reproduction quality of vinyl, CD, DVD, download files, Tape, LP and any other source are now reality. The improvements are described anywhere from "truly amazing" to "incredible".
While some near perfect recordings will not need much linearization, good recordings will become great, mediocre recordings will become rather nice and some downright unlistenable recordings will become listenable. The improvements are rather intriguing and must be experienced to be fully realized.


They - massively - improve any system

FM 133 & FM 233 Harmonic Linearizers
Harmonic Linearizers fit into any system


Two connection possibilities for domestic systems:

a) in the preamplifier tape loop (see above sketch)




b) in-line between preamplifier and power amplifier (see drawing below)


FM 133 & FM 233 Harmonic Linearizer configuration
Easy in-line configuration

In professional applications various routing/connections are possible



Astounding improvements


After a tremendous research program and after dozens of rejected circuit topologies the combination of several ingenious ideas brought the final breakthrough: with the new Harmonic Linearizers the improvement of any type of source signal is now reality.
The FM Harmonic Linearizers are universally usable in any system and bring astounding improvements in any professional or domestic application where audio is involved.


This is clearly the most important improvement in high class audio systems.


If you are interested in a presentation of the FM 133 & FM 233 Harmonic Linearizers please advise FM ACOUSTICS. You will be contacted by our nearest representative.