Unique performance: the FM 330 Series 3-way and 4-way Electronic Linear-Phase Crossovers. FM ACOUSTICS' Harmonic Linearizers allow adjusting the strength (or weakness) of critical frequencies. Thanks
to this absolutely unique design, which only uses 5 easy to adjust controls, any frequency or group of frequencies in the entire audio band can be optimized without negative influence on the audio signal. The Linearizers do what producers, engineers and music enthusiasts the world over have been dreaming about for dozens of years. For the first time, obnoxious sounds in any music source can be attenuated (subtracted) and weaknesses of certain parts of the music spectrum can be strengthened. All this can be done whilst the characteristics and transparency of the original signal are kept intact.
The unique concept guarantees that all of the above is done without any negative influence on the signal path. In fact, the method of operation is rather intriguing as can be seen from Fig. C: the entire audio signal is directed right through from input to output avoiding phase changes and all other negative influences.
The actual response improvement is done by a unique additive/subtractive phase accurate bank of 5 individual Linearizers that combined can correct any frequency aberration in the audio band. The signal always passes straight through from the input to the output even when the strength of a band is adjusted via the front panel controls. While looking at the front panel one could be reminded of an equalizer. However, Linearizer's mode of operation is very different and avoids all the problems associated with equalizers. It's unique characteristic allow linearization of any source by only adding or subtracting critical areas of the audio signal to/from the direct through signal. The result is that there is no ripple in the pass band and nophase shift / discontinuity, which results in pristine signal coherence and superb transient response. Another singular characteristics is that when all level controls are in full boost position there is no change in frequency response; a linear gain over the entire frequency range is achieved; this is the sign of perfect linearization.
FM ACOUSTICS' Linearizers have been designed with optimal reproduction of musically relevant information in mind. Therefore, boost and cut levels are kept to an optimal but not excessive range. Accurate selection and extremely tight component tolerances are required. No op-amps, IC's, transformers or hybrid circuits can be used. In the tradition of FM ACOUSTICS discrete enhanced Class A precision amplifiers are used so that no phase changes, non-linearity or other negative effect occur. Thanks to their unique characteristics it is now possible to linearize audio signals with the assurance of only positive effects on the direct through audio signal. A good demonstration of the Linearizers inherent transparency is to first listen to the standard signal having all controls in the center detent position. Listen carefully to the all frequency ranges. Then turn one of the control, say the 800Hz control and while turning the control, concentrate on another frequency band, say the lower range of voices and low/mid based instruments. You will realize that when turning the 800 Hz control there is absolutely no change in the other frequency ranges! Only the one frequency that you are subtracting or adding is changing while the signal remains pristine and totally transparent, exactly like the original signal! Do not try to work with the Linearizers like you would with an equalizer. It does not work that way. On the Linearizer section every control is dynamic, every movement of one control influences the other. So it is best to control the individual linearizers dynamically: move one control until you hear it is too much addition or subtraction, then move it back to the point where it becomes a realistic correction. Next, move the control adjacent to it say the next lower frequency) by turning that control until again it becomes excessive. Turn it back until the setting becomes correct, then readjust the previously set control mildly until the optimum setting between these two controls is found. Then move to the next higher control and repeat the procedure. Listeners "come to grips" rapidly with the Linearizer controls. An initial hesitation quickly reverses to enthusiasm as soon as a few recordings have been linearized. After a couple of hours practice users get rather comfortable with the controls and often adjust two controls simultaneously. This way they are able to control dynamically and find the optimum setting in seconds. Sometimes one needs to adjust during playing. The reason is that titles or movements of works were recorded on different dates and/or by different engineers and sometimes even in a different location. It is not uncommon to hear noticeable changes in sound from one title to another on the same recording. While some great recordings may not need much of the linearizer function, others will become even greater; mediocre recordings will become very nice and some downright unlistenable recordings will become very listenable; an absolutely amazing feat. Please see the PDF link above for more information.