AJH Synth MiniMod VCF User 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

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