I learned more about Mocante today. The first investigation looked more closely at the CV and gate outputs.
CV and Gate Outputs
I patched the CV output into the 1V/octave control input of a VCO and monitored the control voltage coming out of the Mocante on a ‘scope. The first thing to note is that without any triangles pressed the output is centered around 4.5 volts bias and is quite noisy. Secondly, the position of the pitch basis pot is very important: it needs to be set at maximum to reduce the amount of noise when a triangle is pressed. Thirdly, if more than one triangle is pressed, the output appears to become undefined again. As for the Gate output, it is also very noisy unless the pitch basis is turned up fully. The Gate output could even be used as an audio noise source.
Here’s the sound of stepping up the triangles when controlling an external VCO. For the second half I lowered the initial frequency of the VCO.
All of the following recordings are of direct outputs of the Mocante.
Square Pad Octaves
For this investigation I probed each of the square tone output pads. Each of the 24 Mocante oscillators has 12 square pads associated. The point of each triangle pad indicates the center point of a group of four, which is three layers deep. Between the three layers runs a common terminal, which picks up the signals for routing to the Square Drones output. The 12 pads in each set correspond to 12 octaves, based on the common pitch basis. These are generated by digital division.
The diagram above shows the arrangement of the twelve octaves, from the perspective of looking at the surface directly in front of you. All 24 sets of 12 pads use this arrangement of octaves. The point of the triangle lies just below the line separating octaves 11 and 12. Unless you have tiny fingers, it is difficult to touch less than four squares at once. (And just above the inner pads, like the bending oval pads.) An obvious playing technique is to roll a finger across the pads, side to side and inner to outer, to pick up octaves selectively. Twelve octaves is a huge distance in pitch, and as you can see, the highest and the lowest share a boarder. At this time I haven’t any theory as to why Peter Blasser chose this particular arrangement.
This recording of the Square Drones output demonstrates stepping up and down, staying mostly on pads 7,9,10,11. In the first part the pitch basis knob is centered. Then it is lowered. One surprise is that the intervals don’t always go upwards! Some step down in pitch. (A manufacturing error: wrong capacitor?) Also note, especially when the pitch basis is lower, the presence of tick sounds. These are the lowest octaves, which easily fall under 10 hertz.
The next recording demonstrates the various octaves, keeping the finger on only one set of 12 pads. I played around with the pitch basis knob, and bumped the bending ovals a little.
Witches Tones Outputs
Probing the circular pads, I discovered a strong, steady square wave (that degenerates to a triangle at very high frequencies) being put out on each circle. Something happens internally, so that when touched, the resulting output is a complex cross-modulation of some kind. I wish I had a schematic! The Soft Witches Tones output remains at a constant level, while the Hard Witches Tones is gated on and off by touching the circles. Here is what the Hard Witches Tones output sounds like.
I did a little improvisation, combining the square and witch tones and playing with multiple fingers.