Synthi AKS External CV and Gate Interface Unit
Built into retro looking trapezoidal shaped plastic case which
matches the texture of the
AKS spartanite attache case quite well. Different coloured
knobs
will be an option. Knobs, jacksockets, dials etc are all
identical
to EMS originals. Panel layout is an attempt to keep with the wonderful
styling of the Synthi AKS. Panel is cnc engraved anodised aluminium
with paint infilling.
The Synthi AKS CV & Gate interface unit allows individual switching of the 4 channels (Input ch1, Input ch2, matrix row 16 (joystick vertical control) and gate) between either external CV1-CV3, gate (via 6.35mm jacks) or Keyboard (KS) function of the AKS.
The unit has two voltage inverters.The first allows inversion of CV3. The reason why I added the invert possibility is because the Synthi AKS (and VCS3) all require negative pich voltages to control osc frquencies via Input ch1/2. This is because these channels actually INVERT any signal passed into them. For proper pitch control of oscillators when using the CV3 channel its necessary to place the toggle switch on the CV3 invert setting. By proper control I mean increasing positive CV3 gives increasing Osc frequency. Flicking the CV3 invert switch off (so CV3 is no longer inverted) gives the opposite control whereby more postive CV3 pitch voltages gives LOWER frequency Osc pitch. Bit like a backwards keyboard! This setting is still very useful for producing weird effects or if you want to use CV3 to control things like filter freq etc.
The second inverter acts on input channel 2 voltages form the AKS keyboard (called ‘KS invert’ on the front panel). This allows inversion of the trapezoidal dynamic envelope that the keyboard of the AKS generates via input channel 2 when keyboard is played. Useful when using this keyboard generated envelope to modulate things other than Output channel levels.
The power for the unit is taken from the Synthi AKS
via the
Jones socket and is very minimal since its just a few milli amps that
are needed for the opamp voltage inverters.
The unit features precision 25-turn trimmers accessible from the rear that allow precise adjustment of the 0.32V/Oct CV scaling (as opposed to the standard 1V/Oct scaling found on most synths) needed to play chromatic pitches via external cv sequencers etc using Osc1/2. Toggle switches on all 3 CV channels allow either a 1V/Oct scale range of 0.32V/Oct scale range to be used. See the userguide for more details.
As an example of how this unit can be used:-
You could have the AKS sequencer send pitch sequences via CV3
controlling eg Osc1 via row 16 of the matrix. Another sequencer or the
AKS keyboard could send pitch to CV1 which could eg control Osc2 via
input ch1 and finally have either AKS or external CV2 control filters
etc via dynamic envelopes. The triggering of the Envelope Shaper could
either be by an external gate or the AKS sequencer.
Of course there are other creative combinations
which I am sure you can come up with!
Please note: a special version is available for use with a Synthi A because the Synthi A (as a mk1 unit) does not have the feature that row 16 of the matrix can double as joystick vertical control or an input via jones plug pin8. The Synthi AKS (and VCS3(mk2)) have this feature. So for the Synthi A, a speclal pin cable has been designed to carry CV3 to the matrix. See the userguide for more details.