Doepfer A-107 Multitype morphing Filter

The module contains 26 very different filter types which can be combined each after the other. You can morph or switch between those filter chains manually, with contol voltage or with a clock signal. 15 filter types are known from the Oberheim Matrix 12 and there additional 21 new filter types.

The filters are organized in two groups of 18 filters each. The transition between different filter types within one group can be soft (morphing) or hard (switching).

The transistion between the different filter types is controlled by two parameters: Filter Step (marked Step at the front panel) and Morphing Time (marked Morph at the front panel). For both parameters manual control, one CV input with attenuator and one CV input without attenuator are available.
The 36 filter types can be arranged in filter chains (resp. filter sequencer or filter orders) so that this sequence of filters is passed through while the control voltage changes from 0V to +5V. Each chain consists of 32 steps. 64 filter chains can be programmed by the user and stored in the non-volatile memory of the module.

Of course the standard VCF controls are available: cutoff frequency and resonance. both are voltage controllable. For the filters of the first group (1-18) self-oscillation is possible, the filters of the second group (19-36) do not feature self-oscillation.
On top of it a final VCA is available.

The filter design is 100% analog (CEM filter chip). Only the morphing control and memory managing is carried out by a microcontroller.