AJH Synth MiniMod VCO - Manual

VCO User Guide
Thank you for purchasing the AJH Synth MiniMod VCO module, which like all AJH Synth Modules,
has been designed and handbuilt in the UK from the very highest quality components. We hope
that it will help and inspire you towards creating some great music and soundscapes!
The discrete all transistor core of this Voltage Controlled Oscillator is an exact emulation of the
original, and now very rare, R A Moog Model D Oscillator from 45 years ago. It features a fully
matched PNP transistor expo. converter and P-FET transistor buffer amplifier section but with the
advantage of much improved temperature stability and modern construction using reliable
precision SMT components along with Eurorack modular synthesiser expandibility.
It features front panel switchable octave selection and four independent waveform outputs
including the famous “Sharktooth” waveform, Sawtooth wave, Square wave and Triangle wave
and when used as part of a full MiniMod system can provide a very accurate emulation of the
Model D systhesiser and it’s highly acclaimed “fat vintage” analogue sound.
The Square wave output has fully adjustable Pulse Width Modulation, with manual and CV control
rather than the more restricting selection of square wave or two static fixed pulse widths of the
original design.
Also included are Exponential and Linear modulation inputs and two different types of oscillator
sync which help to make this a very versatile Eurorack VCO in its own right.
Module width is 14 HP of EuroRack space and it is compatible with standard Euro Rack cases. The
height of the panel is 128.5mm, and depth is 38mm. There are four mounting holes at the corners
of the module and we provide 4 of M3 rack fixing screws, along with a Eurorack compatible
power cable. Current consumption is 55mA from the +12V supply rail and 40mA from the -12V
supply rail.
All AJHSynth modules are covered by a one year guarantee against manufacturing defects.
Notes:
As with all vintage analogue oscillators, after powering up it is best to be allowed to “warm up” for 15
minutes or so before use. Tuning immediately after power up is not advised as it takes time for the
internal circuitry to get up to temperature and stabilise. After the warm up period it will maintain pitch
well - much better than the original on which it is based!
It is very important that the power supply ribbon cable is connected correctly, see the “adjustment and
calibration” section for an illustration of the correct orientation.
Vintage discrete transistor core VCO
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