Doepfer A-100(~ 40 MB) User Manual

Page 631

DOEPFER

System A-100

BBD Module A-188-1

Consequently for all clock patches from and to the A-188-1
only short patch cables (~ 30 cm) should be used as long
cables function as low pass filters for signals above 20kHz.
The max. frequency at this output depends upon the BBD
used in the module and is related to the max. clock
frequency of the BBD in question (pls. refer to the table on
page 3). It is about 250 kHz for BBDs with 2048 and 4096
stages and about 450kHz for BBDs with 1024 stages and
less (i.e. a bit more than the max. clock frequency of the
specs in the data sheet). If the BBD circuit is changed the
max. frequency has to be re-adjusted with a trimming
potentiometer on the pc board of the module (frequency
offset). For details please refer to the appendix of this
manual.

CV Out:

CV output HSVCO

This CV output indicates the clock frequency at output

and is nothing but the sum of all CV inputs (manual, CV1
and CV2). The main purpose of this output is to control the
CV input of one or two external low pass filters that can be
used as anti-aliasing filter and clock filter. If desired one low
pass filter can be used behind the audio output to suppress
the clock noise when the clock frequency falls below ~20
khz. Another filter can be used at the audio input to reduce
the max. frequency of the incoming audio signal,
consequently reducing aliasing artefacts. As the CV output
reflects the clock frequency (affected by the manual control,
CV1 and CV2) the external filters automatically follow the
clock frequency of the BBD module. The higher the slope of
the external filter (e.g. 12/24/48 dB/octave) the better is the

clock suppression. But the CV output can be used for other
applications as well, e.g. controlling parameters of the
feedback loop like feedback amount/polarity (CV of a VCA
or VC polarizer used in the feedback loop), filter frequency
(CV of a VCF used in the feedback loop), phase shift (CV of
a VC phaser used in the feedback loop).