DOEPFER
DOEPFER
DOEPFER
DOEPFER
Each tap is connected to two polarizers (the polarizer
function is described on the last page). One of the polarizers
is assigned to the sub-mixer 1, the second to sub-mixer 2.
The sub-mixers are labelled adder with the Σ sign (sum) in
the module scheme. The reason for the polarizers instead of
simple attenuators is that the polarity of each tap is crucial
for the output mixing (for both tap output + original signal
and even for the taps among each other).
The following sketch shows the difference between adding
and subtracting one tap output to/from the original signal by
means of a simple sawtooth signal as audio input.
Fig. 4: positive/negative mixing of original and BBD signal
System A-100
The two sub-mixers are used to mix the outputs of the six
BBD taps with adjustable levels and polarities. Each sub-
mixer has available wet/dry control to adjust the relation
between the original and the effect signal. The effect signal
is the sum of the tap outputs.
The A-188-2 features a feedback section that is very similar
to the one in the A-188-1. But as now six different BBD
outputs are available even six different feedback types are
possible. The feedback input socket is normalled to the 396
output. But by patching the feedback socket to any of the
other single output sockets another BBD tap can be used for
the feedback to a obtain different sound. Even external
feedback processing is possible (e.g. a VCA or a VC
polarizer for voltage controlled feedback, or other modules
like filter, phaser, frequency shifter, waveshaper, wave
multiplier, ring modulator or another BBD module for special
voltage controlled feedback effects). The feedback control
has polarizer function, i.e. the neutral position is at the
center. Left from the center the feedback signal is
subtracted from the input signal, right from the center it's
added (negative/positive feedback). The polarity of the
feedback signal leads to clearly audible different sounds as
different frequencies are emphasized or attenuated for
positive or negative feedback.
BBD Module A-188-2
6
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