AJH Synth MiniMod VCO - Manual (Page 3)

6 Linear Input : This is the Linear Control Voltage Input. Acceptable input voltage range is +/- 5V. This is a
more subtle modulation effect which varies the oscillator pitch by up to +/- 7 notes
depending upon the setting of the Linear CV Level Control (7)
7 Linear CV Level : Controls the amount of Linear Modulation applied to the oscillator core from the Linear
CV Input (6)
8 Sync Input : A rising pulse waveform of +/- 5V (e.g. the Saw waveform from another MiniMod VCO)
can be applied to this input to prematurely reset (synchronise) the oscillator waveform for
interesting sonic results. The sync effect is very level sensitive and is set using the Sync
Threshold control (9).
If it is desired to use a falling ramp waveform from a different oscillator for sync it will
need to be fed through an invertor to convert it to the rising ramp waveform required for
effective triggering.
9 Sync Threshold : The Sync effect is very level sensitive and the waveform level from the Sync Input (8))
presented to the oscillator core can be set using this control. Start with the control fully
counter clockwise and gradually increase it until the desired effect is obtained. The
frequency relationship between this oscillator and the synchronising oscillator plays a
large part in the resulting sounds created. Experiment!
10 Sync Type : This switches between two different sync types. With the switch “down” regular sync is
effective, which can be used to create ripping “laser harp” type sounds. With the switch
“up” a ramp rather than short pulse is applied to the oscillator core reset transistor and
some interesting harmonic and stepped frequency effects can be created. Different Sync
threshold levels are required for the “up” and “down” Sync switch positions.
11 Saw Output : Rising ramp waveform output. It has a level of +/-5 volts centred around 0v. The output
impedance is 1Kohm.
12 Triangle Output : Triangle wave output. It has a level of +/-5 volts centred around 0v. The output impedance
is 1Kohm.
13 Shark Output : The famous “Sharktooth” waveform from the early Model D synthesiser. It has an output
level of +/-5 volts centred around 0v. The output impedance is 1Kohm.
14 Square Output : Square wave output. It has a level of +/-5 volts centred around 0v. The duty cycle
(amount of time the waveform is “high” against “low”) can be varied with the Manual
PWM control (15) or under voltage control (16). The output impedance is 1Kohm.
15 PWM Shape : Adjusts the duty cycle of the square wave between approximately 10% and 90%. When
set to the half way (12 o’clock) position the duty cycle is 50%, which creates a regular
square wave.
16 PWM Control : A control voltage can be applied to the PWM CV Input to vary the PWM duty cycle. The
control voltage range should be between +/- 5volts and the intensity can be controlled
between 0% to 100% with the PWM CV rotary control knob. A low frequency triangle
wave to the PWM CV Input will give the classic sweeping PWM effect. The PWM Shape
Control is still effective when using PWM CV and it changes the offset level.