Fourm Oscillator and Filter Calibration

The natural imperfections of analog circuits are a key part of what creates the character people describe as the analog sound. With analog oscillators, the starting point of each waveform varies since they run freely and continuously. This behavior also differs from voice to voice, contributing to the unique quality of analog instruments.

When checking tuning, it is best to rely on your ears rather than solely on a tuner. Small deviations of a few cents voice to voice are expected. That said, if the instrument is audibly out of tune, you can recalibrate it using the built-in tuning procedure:

1. Press the Global switch to enter the Global Menu. 

2. Use the Select encoder to scroll to option 32: Tune Voices. 

3. Push the Select encoder in to change to the lower display field.

4. Press the Inc switch to the right of the Select knob to begin calibration. 

Allow the process to run until it completes. Once finished, the OLED will automatically exit the Global menu and return to your current patch. If calibration stalls for an extended period, power the instrument off and back on, then restart the calibration.

Running oscillator and filter calibration aligns the analog oscillators and filters across all voices as closely as possible. This does not need to be done regularly unless you notice that voices are significantly out of tune.

We hope this helps clarify how the instrument’s tuning works and how to perform calibration when needed.

If you require further assistance with your Fourm, please contact us at support@sequential.com