AJH Synth MiniMod VCF - Manual (Page 4)

This varies the amount of control voltage passed from the Emp. CV Input (14) to the filter
core and it’s range is 0% to 100%. The manual Emphasis Level control (13) is still active
when using external CV control of Emphasis and acts as an offset control.
This is the audio output for the signal after passing through the filter core and would
typically be connected to the Audio Input of a VCA. The output level is dependent upon
the input level, with a single input of +/- 5V to (for example) Audio Input 1 and Audio 2
Level at 100% the gain would be unity, i.e. output would also be +/- 5V.
Power Cable
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A Scale Adjust : Sets the 1V/Oct voltage scaling. To adjust, first remove all inputs, then turn Emphasis
Level (13) to 10 (full on) and adjust Frequency Control (7) for 440hz output. Now apply
EXACTLY 2V to the 1 V/Oct input and adjust for 1760Hz output (precisely 2 octaves
higher).
B Regen Adjust : With no inputs, set Emphasis Level (13) to 10 (full on) and adjust Frequency Control (7) for
440Hz. Now turn Empahsis Level to 8 and turn Scale Adjust Trimmer until the filter just
starts to selfsoscillate.
C Offset Adjust : Adjusts the vactrol circuit offset. FOR MANUFACTURER ADJUSTMENT ONLY, specialist
test equipment is needed to calibrate this trimmer correctly.
D Range Adjust : Sets the frequency range. To adjust remove all Inputs, set Emphasis Level (13) to 10 (full
on) and set Cutoff Frequency (7) to -1 position. Adjust trimmer for 440Hz output.
E Gain Jumper : See previous page.
Note:
This information is given for completeness, the MiniMod VCF is calibrated after manufacture
and under normal circumstances should not require any user adjustment.
Adjustment and Calibration
A Scale Adjust
Red Stripe aligns with -12V as shown
B Regen Adjust
C Offset Adjust
D Range Adjust
E Gain Jumper
If you need any help using this module or have any technical questions please feel free to
contact us at [email protected]