Infinite rotary controls are great, but when we change a patch, how do we know what the value is? Usually, we don’t know until we turn a controller, and then a display will show the value. Some synths have LEDs showing the position. This is great but expensive, so we don’t tend to get it on all controls.
What if there were a better way? Let’s imagine that each rotary controller has two variable brightness LEDs. The brightness of the LEDs tell us roughly what the value is without us having to touch or rotate anything.
Controls which centre at zero, such as pan controls might use a different system. This isn’t absolutely necessary, but is a nice feature. A different colour might be used to differentiate the type from ordinary controllers. The differentiation may even be done by marking the chassis to show the controller has a centre position. It all depends on whether the rotary controllers are single operation or part of some clever interface that changes the function of the controllers.
I would be interested to hear what a synth manufacturer would say about this idea. I think it would be cheaper than the Montage-style rotary controllers that have many LEDs, but give the user instant knowledge about the value associated with each controller.