An endless encoder needs an external value display because, unlike a fixed-range pot, its position carries no value

A 270-degree potentiometer (unipolar knob) has a physical start and end position, so its angle directly shows the parameter value — the position is the feedback. An endless (rotary) encoder instead turns infinitely in either direction and sends relative increments, so its physical position tells you nothing about the current value. This forces a design tradeoff: an endless encoder must borrow feedback from elsewhere — a screen readout or a ring of LEDs — but in exchange one encoder can drive many different parameters and multiple value ranges, and it never conflicts with a stored preset’s value. That is why compact instruments assign a few endless encoders to every parameter, while knob-per-function synths favour pots for immediate, glanceable position feedback.

Examples

Moog Slim Phatty: just four endless encoders control all parameters, with LED/screen feedback. Novation Ultranova: touch-sensitive endless encoders reveal the current value on the display when touched, without turning.

Assessment

Explain why an endless encoder requires a screen or LED ring while a 270-degree pot does not. Give one reason a designer would still choose the endless encoder despite that cost.