FAQ | Why does the external potentiometer or WCP-1 work for only a portion of its rotation?

Discover the reasons why an external potentiometer or WCP-1 may only work for some of its rotation, as well as how to troubleshoot.

Updated at May 23rd, 2023


Many Q-SYS devices support use of an external potentiometer (or the QSC WCP-1 wall control accessory) on a GPIO input to control a parameter or set of parameters. One popular use is to control a gain block in a Q-SYS design.

In this type of application, though, the pot's useful range of rotation may seem oddly limited. That is because the default range of adjustability in a Q-SYS gain block is from -100 dB to +20 dB, a total span of 120 dB. In most listening environments, gain lower than about -50 dB tends to render the audio inaudible. So over almost half the pot's range of rotation, the audio is inaudible (or nearly so), and at the upper end, reaching +20 dB of gain becomes objectionably loud.

It may be much more useful to customize the gain block's minimum and maximum gain properties. For example, a range from -50 dB to +3 dB might be more suitable as a remote volume control for a restaurant or bar background music system, and much easier to adjust to a desired sound level.