A-188-9

HVO (High-Speed VCO)

(Superbooth 2024)

Module A-188-9 is a so-called high speed VCO that tracks prefectly to the 1V/oct scale in the frequency range of about 10kHz ... 400 kHz. The main application is the exact drive of BBD modules (A-188-1/2) to generate sounds realized by means of the so-called Karplus-Strong synthesis. But even in cooperation with other modules featuring high speed inputs (e.g. digital noise) the A-188-9 makes sense. In principle the module is made of a precision audio VCO followed by a PLL (phase locked loop) unit that multiplies the frequency of the audio VCO by 32. Thus the module can be used also as a simple precision audio VCO as it features the standard waveforms sawtooth, triangle and rectangle with adjustable pulse width.

Controls:

F: frequency control (coarse)

CV2: attenuator for the frequency control input CV2

Fine: frequency control (fine), small control without knob

PW: pulsewidth control for the rectangle output of the audio VCO, in HSVCO mode this control has to be in the range marked "HSVO", small control without knob

Sockets:

CV1: frequency control input 1V/oct scale 

CV2: frequency control input with attenuator CV2

socket with rectangle symbol: rectangle output of the audio VCO, the pulse width of this output is adjusted by means of the control PW, output level ?V

socket with sawtooth symbol: sawtooth output of the audio VCO, level ?V

socket with triangle symbol: triangle output of the audio VCO, level ?V

socket with inverted comb symbol: high speed VCO output, waveform rectangle, level 0/+5V

Switch:

left position: audio VCO mode (frequency range of the audio VCO about ??? Hz to ??? kHz, the high speed output is not usable in this mode ! )

right position: High Speed VCO mode (frequency range of the high speed output about 10 kHz ... 400 kHz, frequency range of the audio VCO about 300 Hz ... 12 kHz), in this mode the audio VCO and the high speed VCO can be used simultaneously

https://doepfer.de/A1889.htm