I was using a Peterson Strobe Tuner pedal. Please refrain from using an oscilloscope, it’s harder and less exact.
Disclaimer: I have never calibrated a standalone SEM module, I’ve only worked with a Four-Voice System (FVS).
Preparations VCO 1 & 2
- Let the unit warm up for 15-20 minutes
- VCO 1 FREQUENCY knob = Center
- VCO 2 FREQUENCY knob = Center
- VCO 1 MODULATION knob = Center-detent (muted)
- VCO 2 MODULATION knob = Center-detent (muted)
- VCF RESONANCE = 0
Preparations VCO 1 in VCF section
- VCO 1 knob = Max SAW
- VCO 2 knob = Center (muted)
- EXT Input knob = Center (muted)
Calibrating VCO 1 (wordy)
- Offset: Send a low note (e.g. C2) or low voltage (0-1V) depending on your analog / digital circumstances
Adjust the Top VCO Trimmer (INIT FREQ) until you have a low C. (If you can’t obtain C, adjust the FREQUENCY potentiometer on the front.) - Scale: Send a note 4 octaves higher (C6 or 4-5V)
Adjust the Middle VCO Trimmer (HI-FREQ TRACK) until you have a high C - Repeat 1 – 2 until they don’t change anymore
Preparations VCO 2
- VCO 1 knob = Center (muted)
- VCO 2 knob = Max SAW
- EXT Input knob = Center (still muted)
Calibrating VCO 2 (concise)
- Low note: C2 / 0-1V
Adjust Top Trimmer until you have a low C - High note: C6 / 4-5V
Adjust Mid Trimmer until you have a high C - Repeat 1 – 2 until they don’t change anymore
Comments
- It should be easy to calibrate a SEM module. The process is straightforward and CV tracking is very linear. If you’re having difficulties tuning it, there’s something wrong.
- If you’re calibrating a Four-Voice- or Eight-Voice System you need to make additional initial settings, please refer to the FVS article: oberheim-fvs-four-voice-system-tuning