Doepfer A-100(~ 40 MB) - Manual (Page 130)

A-108 6/12/24/48 dB Low Pass System A - 100 doepfer
8
6. Changing the assignment of the
four low pass outputs
Only 4 output stages are available as this seems to be
sufficient from our experience. In the factory the 4
outputs are connected to the filter stages with 6, 12, 24
and 48 dB cut-off slope. This is a well-considered
compromise as these outputs generate audible diffe-
rent sounds. E.g. the audible difference between the
48dB and 42dB or between 42dB and 36dB is very
little. So it would make not much sense to have 30, 36,
42 and 48 dB available instead of 6, 12, 24 and 48 dB.
But if desired any of the 8 filter stages can be connec-
ted to one of the 4 outputs. By changing the internal
connections (jumpers or wires) each filter stage is
available - but only four at a time. Even a multi-way
switch could be used but from our results the factory
setting (6/12/24/48dB) is the best combination for mu-
sical applications.
The factory settings can be changed if the correspon-
ding jumpers on the pc board are removed and re-
arranged for the desired new output combination.
On the pc board 4 double row pin headers are avai-
lable (see picture on next page). The positions of the
jumpers on these pin headers determine the assign-
ment of the filter stages to the outputs. One pair of
jumpers is responsible for each of the filter stages. The
factory setting of the jumpers is marked black.
These are the possible jumper settings (the factory
settings are printed bold):
• Output 1: only 6 dB possible
• Output 2: 12 dB or 18 dB
• Output 3: 24 dB or 30 dB or 36 dB
• Output 4: 42 dB or 48 dB
In principle each filter stage can be connected to one
of the four output stages but this would require additio-
nal wiring and cannot be carried out by changing the
jumper settings only (e.g. 18 dB to output 3). All
combinations not listed above have to be made with
wires two by two instead of the jumpers. The upper
row of the pin headers are the 8 filter stage outputs in
pairs. The lower row of the pin headers lead to the
inputs of the 4 output stages in pairs whereby the pins
below 6 db belong to out 1, the pins below 12 and 18
to out 2, the pins below 24, 30 and 36 to out 3 and the
pins below 42 and 48 to out 4. For details please refer
to the A-100 service manual (additional charge).