Doepfer A-188-2 Tapped BBD Module - Manual (Page 7)

DOEPFER System A-100 BBD Module A-188-2
7
The feedback can be increased up to self-oscillation. In
contrast to other feedbacks (e.g. filters or phasers) the result
in the self-oscillation state depends upon the "audio history"
(i.e. the contents of the BBD when the self-oscillation is
triggered). The reason is that there is not only one possible
stable self-resonant state for the BBD. Any cyclic waveform
"stored" in the BBD is able to resonate provided that the
feedback maintains the waveform. One can try this out e.g.
with different audio signals (e.g. digital noise and VCO
sawtooth) as audio input before self-oscillation is triggered.
A special feedback can be obtained if one of the sub-mixer
outputs is used for the feedback function. In this case for
each tap the positive or negative feedback share can be
adjusted. This leads to multiple peaks and/or notches in the
frequency response of the module.