Tactile keyboard Surface
The surface consists of 29 individual keys comprising 2-1/3 octaves. Each touch of the keyboard
generates a pulse, a pressure CV, and pitch CV. These outputs are placed in the upper left of the
218, expecting to be plugged directly into the nearby the pulse, pressure, and pitch CV inputs of a
208.
The pulse output is red banana on the upper left. A red LED
will indicate every pulse output. The pressure CV output
correlates to the detected amount of finger contact on the
current/last single key touched. The blue LEDs next to the
pressure output will get brighter as the voltage gets higher.
The “pitch” output corresponds to the 1.2v/octave pitch of the key.
At the Buchla standard of 1.2v/per octave, that means that the pitch C will be 0v,1.2v, 2.4v, 4.8v or
6.0v depending on the octave being played. (Notice how conveniently that relates the MIDI “C”
notes 0, 12, 24, 48 and 60.) Every ½ step higher will be .1v higher.
To the right of these outputs is Portamento control. Adding portamento will
make the pitches slide from one to the next like a violinist sliding a finger to
the next pitch. It is an endearing musical affect. To control the speed of the
slide, turn the knob higher. At 0, it does not slide; At 10 it may take several
seconds to reach the next pitch. The input banana is another way to control
this parameter with a CV. The CV input will add to the portamento time set
by the knob.
To the right of portamento is the Arpeggiator. The 218 will
arpeggiate based on the keys that are sustained with the
fingers or sustain pedal. The switch determines the
PATTERN: whether the arpeggiation is active or whether it
plays an ascending or a random pattern. (For more random
options, see the appendix for information on how set and play
with “directed random”).
Velocity output for all keys corresponds to the velocity of the last key played, allowing the user to
dynamically play the pattern. As on the 2013 218e, a small random velocity variation also keeps the
pattern from being static. (Minimum velocity range for the arpeggiator is set in edit mode.)
The ARPEGGIATION RATE, is controlled by the knob. At knob position “0” the arpeggiator stops
and only a pulse input will advance it. Turning the knob will increase the steady rate of arpeggiation.
(The rate changes on the next event.)
“input”: As per a traditional late-200/200e system, this orange banana indicates that it is a pulse
input. New to the 218e-V3 is the change from CV control of the rate to advancing the arpeggiator
using pulse inputs. Even while the rate is set higher than 0, pulse inputs can also advance it so you
can create interlocking rhythms between pulse inputs and the automatic advances.
(See the Appendix for a way to change that orange banana input from pulse to CV rate control)
Note that the pulser CV out of the 208C yellow jack is a sawtooth envelope, not a pulse, so if you use it
for the arp pulse input, the response may be a little unpredictable. Use a CV to pulse converter to fix
that.
Also note that the V3 version of the 218e starts its arpeggiation as soon as the key is touched, like
normal key performance. Remember to make sure you switch to “none” for basic keyboard
performance, because the instance arpeggiator response can fool you.
