ACO160EVK
Audio‐to‐Synth Evaluation System
5
999 SW 1
st
Ave. #1617, Miami, FL 33130
10) Place the ACO Mode (S1) switch with the upper switch in the right position. You may have to reset
the microcontroller via the reset pushbutton switch. Adjust the SYNC FREQ knob to hear the effects of
hard sync with various sync frequencies. Hard sync on the sine wave is especially juicy! Place the upper
ACO Mode switch back in the left position to enable MIDI output.
Controlling External Synths Via CV/MIDI
11) Patch the PITCH, GATE and ENV signals out to an analog synth of your choice and enjoy “playing”
that synth with the audio source of your choice!
12) Connect the MIDI output to the digital synth of your choice via a standard MIDI DIN5 cable and enjoy
“playing” that synth with the audio source of your choice.
ACO160EVK Calibration
All functions in your ACO160EVK should be fully calibrated before shipment but here is a description of
the calibration options:
1) DC offset at the ACO balanced input is controlled via the “OFFSET” trimpot.
2) Pitch CV 1v/oct calibration is controlled by the “PITCH CAL” and “PITCH OFFSET” trimpots. PITCH CAL
is adjusted to tune the SLOPE of PITCH CV out to 1v/oct. PITCH OFFSET is tuned to set the absolute
PITCH CV output as close to 50Hz = 1v as possible. Note that the PITCH OFFSET trimpot adjusts the level
into a 3‐bit flash ADC which sets the pitch offset to one of eight discrete steps and can be tuned as
follows if 50Hz = 1v is not desired:
Fully CCW: PITCH CV – 210mV (50Hz = 0.79v, 100Hz = 1.79v)
Next step CW: PITCH CV – 140mV (50Hz = 0.86v, 100Hz = 1.86v)
Next step CW: PITCH CV – 70mV (50Hz = 0.93v, 100Hz = 1.93v)
Next step CW: PITCH CV nominal (50Hz = 1v, 100Hz = 2v)
Next step CW: PITCH CV + 70mV (50Hz = 1.07v, 100Hz = 2.07v)
Next step CW: PITCH CV + 140mV (50Hz = 1.14v, 100Hz = 2.14v)
Next step CW: PITCH CV + 210mV (50Hz = 1.21v, 100Hz = 2.21v)
Fully CW: PITCH CV + 280mV (50Hz = 1.28v, 100Hz = 2.28v)
3) The HARM TUNE trimpot tunes the HARM IN CV input to 1v/oct. NOTE: This 1v/oct scale is accurate
only when the HARM knob is tuned to the unison position. If the HARM knob is tuned differently the
HARM IN CV scaling might differ from 1v/oct slightly.
4) CAL button. Pressing this button initiates a fast three‐point auto‐calibration procedure to tune the
ACO160 to the appropriate MIDI notes. Turn off your audio source and turn the preamp and gate
threshold knobs fully CCW to ensure calibration can be executed successfully.
5) Reset button. If you try to convert an especially challenging audio source to MIDI, it can result in
some stuck notes. Pressing the RESET button should send an “All notes off” command and resolve any
such stuck note situation.
