Doepfer A-127 Triple VC Resonance Filter - Manual

doepfer System A - 100 Triple VC Resonance Filter A-127
1
1. Introduction
Module A-127 is a Voltage-Controlled Triple Reso-
nance Filter), consisting of three separate band pass
filters with one common input.
For each of the filters, the filter frequency and Reso-
nance can be manually controlled, and in addition
the filter frequency can be voltage controlled. Each
filter has its own audio output. There is also a Mix
output which takes your chosen amounts of each of
the three filter outputs and the original signal - set by
the Audio Level controls - and outputs them from one
socket.
Each of the filters also has an internal LFO (a triangle
waveform) for modulating the filter, and there are
controls for LFO frequency and amplitude. Instead of
the LFO, an external control voltage can be used,
whose amplitude can be manually controlled.
H There is an alternative scenario:- each of the
three filters can also be configured as a
12dB low-pass filter with resonance con-
trol. To do this, a jumper has to be re-
positioned on each of the three circuit boards
(see chapter 7, Appendix).
A-127
VCRF
Mix Out
ext. CV
Audio
In
Audio Lev.
Resonance
VCF Frq.
CV Ampl.
LFO Frq.
VCF 1
Audio
Out
Audio
In Level
Original
VCF 2 VCF 3