The Amtec BC-5A Band Compressor is an easy to use 500-style analogue
dynamic equalizer capable of changing its frequency response according to the
incoming audio signal. It lets to control unevenness in the selected part of the
spectrum by boosting the selected band during low-level signals and
dynamically reducing it when the signal in the band is excessive.
Depending on the band choice, the Band Compressor can help to make
instruments or voices sound bigger and fuller, with more body and thickness,
but without undue boominess or make them brighter and more present with a
sparkle, brilliance and clarity, but without harshness, sibiliance and listening
fatigue.
The bands of operation range from low frequencies with shelving characteristics to peaking low midrange (centered at 240Hz) or high midrange (centered at 3.4kHz) to high frequency shelving. One band is destined to work at low and high frequencies at
the same time offering automatic "loudness" control, dynamically applying bass and treble boost at low volume levels.
The BC-5A operates only in one of the six selectable bands (the low frequency shelving filter offers internally selectable three frequency point options, so in total there are 8 band settings to choose from) and allows to boost or attenuate the signal in the
band and, additionally, to automatically reduce the gain in that band. The static frequency response is set by the EQ TRIM control, which works as a typical EQ gain knob. Its range is from 20dB of cut to 12dB of boost. This knob sets the basic
frequency response of the unit. The level of the band can be then automatically reduced by the use of the BAND COMPRESSION knob when the energy in the band is xcessive. The dynamic range is reduced only in the selected band, the
rest of the signal is not altered.
The BC-5A uses parallel processing, where filtered, compressed (using FET gain reduction element) and phase manipulated input signal is combined with the direct unaltered path, resulting in minimal signal degradation. It adds filtered signal to the
direct signal for boost or substract it for cut.
Apart from the hardwired bypass (using a relay) there is a facility to mute the direct sound, so that only the processed part can be heard to observe what is actually being added (or substracted) to the signal.
