SND - FB-14 Mk2 Discrete Inductive Range Fixed Filter Bank

Inductive audio filterbank with discrete class A circuitry

-classic class-A circuit design using coils, which have to be custom-made and thus are very costly, but they sound just so much better than standard RC-filters. Only 4 transistors in signal path, 2 of them being selected germanium types, which behave somewhat similar to vacuum tubes.

-14 bands with 2-pole-filters. Center frequencies are 35, 65, 105, 160, 240, 360, 540, 800, 1200, 1800, 2700, 4000, 7000 and 12000 Hz.

-The choice of the frequencies in (nearly) fifth intervals avoids a false ´tonality´ (that is an unwanted emphasis or attenuation of the same musical note in different octaves) that can be found on all octave, semi-octave, and one-third-octave filterbanks.

-The control range per band is +/- 20 dB (!). This corresponds to a ratio of 1/100 compared to 1/16 (+/- 12dB) available on almost all other equalizers and filterbanks. So even drastic sound manipulations are possible that normally require two chained EQ´s. The q-factor of the filters gradually increases from 0.7 at +/-10 dB to 6 at +/- 20 dB.

-The individual filters are not decoupled from each other. Thus all kinds of - wanted - phase changes and cancellations occure. Normally this circuit design has the disadvantage of a very non-linear control curve (all relevant changes happen within a few degrees at either end of the pot´s turn). To compensate this, sealed high quality pots with a special curve are used, custom-made for us by ALPS.

-Input gain and output level controls. Input gain can be set from - 20 to +20dB. Due to its special circuitry, overdriving the unit produces much more interesting results than standard rc-filters using op-amps.

-Frequency range 20-50000Hz +/- 1.5dB, Signal-to-noise ratio 90dB.

-1/4” jacks for input and output. Internal ground-lift for separating chassis and audio ground.

-Bypass (using a sealed relay) through frontpanel push-button and automatically when power is disconnected ("hard-wire bypass").

-19”, 1 unit, depth (behind frontpanel): 58mm + plugs, external power supply.

Available again with all original circuitry. MK2 refers to minor changes to the exterior design.