In this patch we are using the Gemini in Cascade Mode, so the Dual and Invert switches are both in the up position.
By connecting two LP (Low pass) filters in series we can double the cutoff slope of the filter - many famous vintage synths
such as Moog and Arp used 24dB VCF’s, so we can use the Gemini 2412 to mimic this response too.
We are feeding the audio into IN 1, however do note that there is no patch cable in the IN 2 input - it is not needed as in
CASCADE mode OUT 1 is normalised (connected) to IN 2 internally, so the single input is automatically patched to both VCF
1 and VCF 2.
The D-FCV IN input is fed from the contour generator, this saves having to patch individually to VCF 1 and VCF 2 FCV Inputs,
and here we have the D-FCV MIX control at mid point, so that the D-FVC control signal is being sent equally to VCF 1 and
VCF 2, thus it behaves as a single filter.
Rotating the AUDIO MIX control clockwise from zero to 10 fades between single 12dB LP configuration (VCF 1 only) and
24dB configuration (VCF 1 and VCF 2 cascaded in series). You will not that the 24dB setting sounds “duller” and less bright
than the 12dB LP filter - this is exactly as expected, because we are removing higher frequencies at a rate of 24dB per octave
instead of 12dB per octave. The actual filter LP slopes (with resonance set to zero) for the Gemini 2412 are shown in the
graph below.
Note: The numbers used to illustrate control knob positions do not relate to the markings on the module itself, but are simply a scale from zero to 10 with 5
being the control centre position. For attenuverters the control positions are -10 to +10, with zero being centre position for the control knob.
GEMINI 2412 - PATCHING EXAMPLES
10
10
Gate 1
Output 1
10
0
0
0
3
5
3
8
8
1
0
5
2
0
0
4
5
5
5
10
16’
0
0
HP
LP
CASCADE
VCF 2
5
0
0
0
0
0
0
4 - Cascade Mode - creating a 24dB LP filter by combining 2 x LP filters in series
Creating a 24dB LP filter by combining 2 x LP filters in series
A comparison of GEMINI 2412 12dB and 24dB filter slopes
1V/Oct IN
