FB-14 Extended Range
Fixed Filter Bank
audio filterbank with discrete class A circuitry
of production !
class-A circuit design using coils, which have to be hand-made and
thus are costly, but they sound just so much better. Only 4 transistors
in signal path, 2 of them being selected germanium types, which behave
somewhat similar to vacuum tubes.
bands with 2-pole-filters. Center frequencies are 35, 65, 105, 160,
240, 360, 540, 800, 1200, 1800, 2700, 4000, 7000 and 12000 Hz.
choice of the frequencies in (nearly) fifth intervals avoids a false
´tonality´ (that is an unwanted emphasis or attenuation of the same
musical tone in different octaves) that can be found on all octave,
semi-octave, and one-third-octave filterbanks.
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.
individual filters are not decoupled from each other. Thus all kinds
of - wanted - phase changes and cancellations occur. 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 conductive plastic pots
with a special curve are used, custom-made for us by ALPS.
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.
range 20-50000Hz +/- 1.5dB, Signal-to-noise ratio 90dB.
jacks for input and output. Internal ground-lift for separating chassis
and audio ground. A special summing Y-cable can be ordered for connecting
(using a sealed relay) through frontpanel push-button and automatically
when power is disconnected ("hard-wire bypass").
1 unit, depth (behind frontpanel): 58mm + plugs, external power supply.
+ VAT & freight. 5 year warranty.
and excellent sounding filterbank...", "A piece of gear with an
outstanding concept, that plays in a special league and that currently
has no competition worldwide." (Keyboards 1/00)
"... a classy,
smart piece of equipment", "Naturaly this high expense
and the equally high quality has its price. But that is more than
justified because the sonic results are absolutely convincing."
(Florian Schneider, Kraftwerk)