Döpfer A106-6 - XP Multimode filter

Provides 4-pole Lowpass, Bandpass, Highpass, Notch

A multimode filter based on the filter circuit of the Oberheim Xpander. The module features 15 different filter types with 8 filters available simultaneously. The toggle switch Filter Group is used to switch between 2 filter groups.

12 HP (61 mm), 50 mA @ +12V, 50 mA @ -12V, 0 mA @ +5V

Made by Döpfer.

Front panel

                        3A/3A1L
Audio-In       Lev.
                        2N/2N1L

FCV1           Frq.   2H1L/4B

                        3H/3H1L
FCV2           FCV
                        2H/2H1L

QCV            QCV      1H/2B    

                        3L/4L
Filtergrp      Q
                        1L/2L

Labels of switch positions and rotary detents

Filtergrp (switch)
Group 1, Group 2

Filter groups

The types of the 8 simultaneous filter outputs in the rightmost column of the front panel are determined by the filter group switch in the lower left corner.

Notice that output 3 of filter group 1 and output 5 of filter group 2 are equal. Consequently, this multimode filter offers 15 different filter types.

Group 1 (left position)

From top to bottom:

  1. 3-pole allpass
  2. 2-pole notch
  3. Combination of 2-pole highpass and 1-pole lowpass
  4. 3-pole highpass
  5. 2-pole highpass
  6. 1-pole highpass
  7. 3-pole lowpass
  8. 1-pole lowpass

Group 2 (right position)

  1. Combination of 3-pole allpass and 1-pole lowpass
  2. Combination of 2-pole notch and 1-pole lowpass
  3. 4-pole bandpass
  4. Combination of 3-pole highpass and 1-pole lowpass
  5. Combination of 2-pole highpass and 1-pole lowpass
  6. 2-pole highpass
  7. 4-pole lowpass
  8. 2-pole lowpass

External links

See the homepage for more details.

Schneiders Laden has a page about this module.