relative increase/decrease by fixed amount


I'd like to control the filter cutoff and other parameters of my Roland MC-101 via an external absolute MIDI controller but only by a relative amount.

i.e. When my MIDI controller is at 0 then the MC-101 should do nothing, but when i turn the controller to 127, I would like the MC-101 to raise the filter from it's current value by say 50. Then when i turn my MIDI knob back to 0 the MC-101 should return to it's original value.

Is suppose i would be adding an amount to the current amount.

e.g. MC-101 Filter is set at a value of 30. When i turn the MIDI knob from 0-127, the MC-101 filter would rise 50 units to a new value of 80. When I turn the MIDI knob back to 0, the MC-101 filter would return to 30.

Is this possible?


So instead of your knob that has values of 0-127 taking your filter from 30-50 on your MC101, you would like the same incoming values to make the outgoing from 30-80 on your MC1010. Is this correct?

The scaling formula  and procedure for this type of thing can be found in the below tutorial.


If you have any trouble with using it, feel free to come back here with any follow-up questions.


Steve Caldwell
Bome Customer Care

Also available for paid consulting services: