1. INTRODUCTION
Audiophile Circuits League
.
-Variable Sync VCO module consists of one ramp
core oscillator with several wave shaper subcircuits, all having that classical
vintage tone, loved by a lot of musicians and soundsynthesists.
The VCO is
capable of delivering that without sacri�icing tracking precision and low
temperature drift.
Available waveshapes are saw, inverted saw, triangle, sine
and PW rectangle, which uses the saw wave from the waveshaper as a carrier
for the PWM. It can be varied by CV and manually within a range from 0% to
almost 100%.
The possibility to play VCO in low, middle and high modes, together with the 10
turn precision Tune pot results in a very convenient "on the �ly" way of tuning
the module. It's core can be frequency modulated exponentially from two inputs,
both CV controlled. When fully open the input attenuators are calibrated for 1
V/Oct. There is one more input - for linear modulation with manual amount
control, AC coupled and con�igured like differentiator. In this way it is sure no
detuning caused by DC, will take place when modulation signal is presented at
the FM Input, but only frequency modulation, centered around the already
played tone.
Syncing the core to outside source makes a whole lot of difference, when there is
the additional option to vary continuously by CV and manually the threshold of
synchronization from no sync, soft sync and hard sync. This input is con�igured
as attenuverter for even more �lexibility. Note when the Treshold pot is fully CW
there will be no sound output anymore. The reference wave source for the soft
sync is the saw from the oscillator. Sync input itself reacts to every repeatable
waveform with amplitude higher than 1,2 Vpp.
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