The Design Concept; The Vca; Inputs - BBE MAXCOM Owner's Manual

DESIGN CONCEPT

THE DESIGN CONCEPT

THE vCA

At the heart of the MAXCOM lies an industry standard state-of-the-art VCA (Voltage Controlled Amplifier). With
its excellent specifications (noise, THD, control feedthrough, linearity, slew rate and temperature stability) the
precision VCA used in the MAXCOM is considered one of the best in VCA technology. The "control feedthrough"
used in VCA terminology is a very critical parameter for the crosstalk of the control voltage into the audio path.
Slow changes of the control voltage lead to a slow DC offset at the audio output of the VCA and are mostly in-
audible. Fast controls however, will result in awkward switching noise ("clicks").

INPUTS

• bALANCED INPUTS
As standard, the MAXCOM comes with electronically servo-balanced inputs. This circuit design features au-
tomatic hum and noise reduction for balanced signals and thus allows for trouble-free operation even at high
operating levels. Externally induced mains hum etc. will be effectively suppressed. The automatic servo-function
recognizes the presence of unbalanced connectors and adjusts the nominal level internally to avoid level differ-
ences between the input and output signals (correction 6 dB).
• SIDECHAIN INPUTS
Each of the two channels of the MAXCOM incorporates a separate SIDECHAIN insert facility. Using an external
equalizer, this additional feature allows for frequency selective operation. Therefore, the unit can be used as a
de-esser or feedback suppressor.
• AUDIO PATH
The audio signal passes first through an electronically balanced input stage and is then directed through the
VCA which actually governs the dynamic process. The VCA's output feeds the resulting signal into the Sonic
Maximizer. The subsequent potentiometers control the amount of Sonic Maximizer Process and Lo Contour
control which will be used in the main path. The amplifier and output driver leads the signal via the Bypass switch
to the output connector.
• SIDECHAIN PATH
The audio signal is simultaneously directed to the SIDECHAIN. By further processing of this input signal, both
Expander and Compressor Audio Detectors result in a conversion of the audio signal into rectified control volt-
ages. The subsequent Auto Gate and Auto Compressor circuit govern the control characteristics of the gate
and the compressor. They automatically derive the attack and release times from the input signal and therefore
generate a musical and unobtrusive signal processing. The final control voltage is then routed to the VCA.
• SIDECHAIN INPUT
An external signal can be fed into the SIDECHAIN connector which allows the unit to be controlled externally. By
using the SIDECHAIN insert on the back panel the link to the audio signal will be automatically interrupted and
the MAXCOM can now be used for example as a frequency selective compressor (de-esser etc.).