The VCS3 Card for 208
Hi
Thank you very much and congrats on your purchase of the VCS3 Card.
This card expands the Music Easel or 208 with original EMS VCS3 circuits : an
oscillator
that produces
simultaneous square and triangle waveshapes with wide range from very slow LFO to ultrasonic and
features useful modifications (synchronization, shape CV, hi/lo range) and a
noise generator
with
variable colour, together with the acclaimed Portabellabz
random voltage generator
modification
module that expands many original EMS Synthi A, AKS and VCS3.
The inputs and outputs voltages are adapted to match the ones used in the 208.
Oscillator
hi/lo switch
: selects the oscillator frequency range
key switch
: sends CV patched to the 208's keyboard voltage input, typically from a 218 keyboard,
tracking is calibrated to the user's preference and is good on about 5 octave with minimal drift. The
oscillator needs about 10 minutes to warm up and stabilize. Calibration was done with the frequency pot
in central position (C), other setting might affect the tracking range.
frequency top pot
: sets the oscillator frequency.
frequency bottom pot
: sends CV patched to the card's "freq" black banana socket, it's an attenuverter,
0 is the central position, CW is normal CV, CCW is inverted CV. The CV amplitude can be scaled with the
multiturn trimmer next to the pot.
fine
pot
: fine tunes the oscillator frequency.
shape
top pot
: sets the oscillator waveshapes, affects both square and triangle together, in central
position, the waveforms are symetrical, fully CW or CCW mutes the square, this is normal behaviour.
shape
bottom pot
: sends CV patched to the card's "shape" black banana socket, it's an attenuator,
CCW is 0, CW is maximum.
square and triangle level pots
: waveform level sent to the mixer.
sync pot
: sends signal patched to the card's "sync" black banana socket to slave the card's oscillator, it's
an attenuator, CCW is 0, CW is maximum. This oscillator's sync is far more tonally versatile than any other
analogue synthesizer commercially available. Typical master is the 208's MO via its "mod CV out" socket,
the envelope and pulser in fast self mode work as well, the CO is a great master, a dedicated pre-LPG
output is possible thanks to a small modification of the 208 detailed in the VCS3 Card build notes
available on my website.
Noise and random voltage generators
colour
pot
: sets the noise colour, CCW promotes low frequencies, CW high frequencies, the pot setting
affects the random voltage output.
level pot
: noise level sent to the mixer.
noise / random mini slide switch
: behind the panel, next to the white banana socket, selects between
noise and random voltage on the white banana, this affects this output only and the noise is still available
in the mixer when switched to random.
The noise generator needs about 30 seconds to start working, no sound or random voltage immediately
after power up is normal behaviour.
Sockets
square and triangle blue bananas
: full range modulation outputs of the oscillator.
white banana
: modulation output of the noise and random voltage generators.
red banana
: modulation output of the mixer.
orange banana
: random voltage generator clock input.
black bananas
: CV inputs to the oscillator, as described above.
tinijax
: audio output of the mixer, to be patched into the 208's preamp "signal in" tinijax.
