Radikal Technologies - RT-451 Dual Multimode Filter

Both flexibility and character are main assets of this dual multi-mode filter module. Of course you can use it as two individual filters but smart normalizations, a common cutoff coupler knob and polarizers at the cutoff CV inputs allow for the use as an outstanding stereo filter. It can sound warm and vintage and even aggressive but it's also fantastic with high resonance. Even sub basses and earthshaking bassdrums are no problem for the RT-451.

Both filters ot the RT-451 module are identical, for which reason one one will be described. Each has one input with a gain cntrol and an audio output. The cutoff frequency can be modulated by two CV inputs and the Q by one. All CV inputs have modulation intensity controls (see below). For each filter three switches activate the possible filter modes (low pass, band pass, high pass) which allows you to mix and to combine the filter types.
At maximum resonance the filter will oscillate and it can track one volt per octave.

A special attention hast to be turned on the common use of both filters simultaneously:
The "coupler" control determines both filters' cutoff frequency at the same time whi ch is highly practical when you use both filters together, no matter if in a parallel or serial manner.
All CV inputs of the first filter are normalized to the inupts of the second filter and the cutoff CV inputs have bipolar controls instead of normal attenuators. In conbination with the normaliszations describend earlier one CV can have different effects on the cutoff frequencies. This makes modulations in opposite directions possible which are really great when using the module in stereo.