User Manual

MOD BUS and Timbre Shaping Sections:
Mod Bus
The internal Mod Bus SOURCE is hardwired for VCO A SINE wave, with the power to use any external
source by patching to the EXT. SouRCe Input. The internal MOD bus system makes use of the Normaliza-
tion Switch found on the mini-jacks, so with nothing patched to the Shape, Angle and Fold CV inputs the
associated attenuator sets the final amount of modulation applied to the destination. As you increase the
Index level, the amplitude of VCO A Sine bused to the SHAPE, ANGLE and FOLD jacks is increased. There-
fore you could have different amounts of modulation at each of the destinations (SHAPE, ANGLE, FOLD).
TIMBRE
The 3 parameters that are modulated by the MOD Bus shape the signal that is output at the FINAL OUT.
The top-most parameter in the Timbre section, SHAPE, adds higher order harmonics to the signal by morph-
ing from SINE (0%) to SPIKE (50%) to Glitched Triangle (100%) while at the same time inducing phase
reversal and amplitude modulation around the 50% range of the parameter value. This might sound like an
odd collection of waveforms and functions, but the selection is quite useful.
The SINE wave is the classic waveform that would feed a wave folder, as utilized in both the Buchla 259 and
the Buchla Music Easel Timbre circuits. Since wave-folding introduces lower order harmonics to the signal,
the extremely low amount of harmonics in a SINE wave allows the circuit to do its job perfectly, resulting in
smooth and glitch-free folding of the waveform.
The Spike shape on the other hand is rich in higher ordered harmonics and morphing from SINE to SPIKE
without any folding of the waveform (FOLD set 10% to 30%) provides something like the effect of high pass
filtering. The SPIKE waveform is useful in providing a strong group of harmonics for the ear to follow while
modulating the ANGLE parameter or utilizing the lower octaves (mix with the SINE OUT to brighten bass
sounds). The SPIKE wave shape is thin and resonant sounding, making the FOLD circuit feel almost anemic
(in contrast to being fed a full blooded SINE shape).
The Glitched Triangle brings the combination of the strong Harmonic that makes the ANGLE modulations so
animated and the girth of the SINE wave that gives the FOLD circuit some fat to chew, er FOLD!