The Gemini’s multimode filters are identical in design. The circuits feature an edge steepness of -12 dB per octave. Each channel offers an audio input with level potentiometer. A rotary switch is used for selecting high-pass, band-pass or low-pass. Alternatively, a variable filter type can be chosen. Here, it is possible to smoothly blend from high-pass and band-pass to low-pass using a potentiometer. Other knobs provide manual control of cutoff and resonance. Both parameters can be modulated via CV inputs as well. The cutoff channel is equipped with a bipolar attenuator. A 1v / octave connector allows key tracking. In addition to the main output, there are individual outs for high-pass, band-pass and low-pass.
A master section allows you to combine both filter circuits. Results are emitted via a separate audio output. In detail, the filters can be wired in parallel or in serial. Using a CV input, you may modulate both filters evenly. In parallel mode, it is possible to crossfade between both filters. This can be done either via a potentiometer or a control voltage. On top of that, the phase of the second filter may be inverted.
The sound of the Gemini 2412 is smooth and voluminous. Frequencies are rather swallowed than cut. True to the SEM, the circuits can’t self-oscillate. However, the module’s resonance appears to be a little more aggressive, making the Gemini 2412 more flexible. Thanks to the routing options, it is possible to perform some rather unusual operations. In serial mode, for instance, you can create vocal-like sounds using both filters in band-pass mode. An example for parallel processing: Create a bass sound with the first filter plus an external envelope and add a rhythmic S&H modulation. Then, start blending in the second filter at regular intervals via another control voltage to add some more harmonic content. – Awesome! Used separately, but with the same settings, the filters are able to process stereo material evenly. Counter-phase modulations lead to panorama effects.
CV inputs for cutoff and resonance
1v / octave input
Individual outputs for high-pass, band-pass and low-pass
CV inputs for filter mix and master cutoff modulations
Power consumption: 50 mA at +12 V and 45 mA at -12 V