The Gemini 2412 is a very comprehensive and extremely versatile dual filter module. Although it is a
complex design, it becomes very easy to understand when we break it down and examine its compo-
nent parts and the relationship between them. The diagrams and text here will get you up to speed
quickly so that you can explore all of the possibilities and capabilities of your Gemini 2412. It comprises:
1 - Two fully independent Multi Mode VCF’s
(VCF 1 and VCF 2)
2 - Audio Cross fader / Panner module
(Mix Bus)
3 - Dual Frequency CV source with external input and panning mixer
(Mix Bus)
4 - Audio Inverter
(Mix Bus)
5 - Parallel / Serial Connection switch
(Dual / Cascade mode)
The block diagram below shows how the above component parts are connected together and the signal
flow between them. It can be seen that either Input 1 or the output of VCF 1 can be routed to the input
of VCF 2 via the Dual Cascade switch. This connection is made using the internal switch on the IN 2 jack
socket, and is connected if no jack socket is connected, but if a patch cable is insered into IN 2 then this
connection is broken and the external signal from the patch cable is routed to the input of VCF 2 instead
- the technical term for this is normalising.
Overview
VCF 1
GEMINI 2412 DUAL VCF - Block layout and signal flow
MIX BUS
VCF 2
IN 1 (Audio In)
+5V
Cutoff Freq.
FCV IN
INVERT
VCF 1 Mode
Res Pot
1V/Oct
RES CV
+5V
MIX CV
+5V
Cross Fader
Audio
Dual Frequency CV Source
FCV Level
Attenuverter
IN 1 Level
IN 2 (Audio In)
IN 2 Level
SIGNALS:
INPUT AUDIO SIGNAL PATH:
DUAL AUDIO SIGNAL PATH:
FREQUENCY CV SIGNAL PATH:
RESONANCE CV SIGNAL PATH:
INTERNAL VOLTAGE CONNECTIONS:
BP Out
D-FCV Level
D-FCV MIX
D-FCV
+10V
Res Pot
RES CV
+5V
HP Out
LP Out
Out 1
Vary Pot
Dual / Cascade
Switch
Self Oscillation
Jumper
Self Oscillation
Jumper
Invert Switch
D-Out
VCF-1
VCF-2
Audio Mix
Cutoff Freq.
FCV IN
INVERT
1V/Oct
FCV Level
Attenuverter
INVERT
LP
BP
HP
VR
VCF 1 Mode
BP Out
HP Out
LP Out
Out 1
Vary Pot
LP
BP
HP
VR
