Doepfer – Doepfer A-106-1 Xtreme Lowpass/Highpass Filter User Manual

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DOEPFER

System A-100

X-treme Filter A-106-1

avoid troubles with the Korg company who is the owner of
the term "MS20". If you want to know more technical details
please look at the document “A-101-1 technical details” on
our website www.doepfer.com (available from the A-101-1
or A-106-1 info page). In this document the basics of the A-
101-1 (Steiner) and A-106-1 ((Xtreme) filters are described.

There are two jumpers on the module.

• The first jumper is located on the main board A (the

right one with the CL+/CL-/Res. controls) and labelled
JP7A/B. In the upper position A (factory setting) the
output is unbuffered and has a noticeable DC offset
(DC coupled). Unbuffered means that the output load
affects the filter behaviour. In the lower position B the
output is buffered and has no DC offset (AC coupled). If
unexpected behaviour of the A-106-1 output appears
try the lower position (buffered mode).

• The second jumper is located on board B (the left one

with the frequency and audio input controls) and
labelled JP4. It is a bit difficult to find as it is located
behind the 10 pin connector that is used to connect the
two boards. It is recommended to remove the female 10
pin connector to change the setting of this jumper. In
the upper position (factory setting) the high pass control
"HP Lev" works as a polarizer (zero = center position).
In the lower position it works as a normal attenuator
with zero at the fully counterclockwise position. If you
do not want to use the polarizer function (i.e.
add/subtract the LP and HP signals) it is recommended

to move the jumper to the lower position. But in this
case the (-)/(+) front panel printing for the HP level
control is no longer valid.

Clipping control option:

The module is prepared to control the CL+ and CL-
parameters by using the universal vactrol module A-101-9.
Two pin headers (JP5, JP6, located behind the CL+ control)
are used to establish a connection to the universal vactrol
module A-101-9. This allows voltage control of CL+ and CL-
. Please refer to the manual of module A-101-9 for details.