Inconsistent Cutoff Parameter Display and Filter Response Behavior

Bug Description

What happens?
The Cutoff parameter on the filter page behaves unintuitively and inconsistently across its sound response and visual representation:

  1. Value Indicator Below Cutoff Knob: The horizontal bar below the Cutoff knob does not reflect changes linearly. While audible changes to the sound can be heard as low as 70 Hz, the indicator bar only begins to move at 390 Hz. This discrepancy makes the visual feedback confusing.
  2. Filter Curve Display Above Cutoff: The filter curve display above the parameter does not align with the actual value. For example, even when the cutoff is set around 400 Hz (indicated by a barely visible bar), the curve already occupies a significant portion of the screen, making it appear as if the filter is more open than it actually is.
    Non-linear Response: There seems to be a non-linear relationship between the knob’s rotation and the parameter’s effect, further complicating intuitive control and visual feedback.

Expected behavior:

  1. The value indicator bar should move in a linear fashion, starting from empty at the lowest frequency (e.g., 20 Hz) and filling completely at the highest frequency (e.g., 20 kHz). As the Resonance knob does perfectly well.
  2. The filter curve should accurately represent the cutoff frequency’s effect in real-time, matching both the parameter’s actual state and the visual indicator bar.
    The parameter should behave linearly in both its auditory and visual feedback for intuitive control.

Steps to Reproduce

  1. Navigate to the Filter Page and select any filter model.
  2. Gradually turn the Cutoff knob from the lowest position to the maximum position.
  3. Observe the following:
  4. Changes in sound start to appear at ~70 - 80 Hz (depending on your ears :slight_smile: , but the indicator bar below the knob does not move / indicates until ~390 Hz.
  5. The filter curve display above the parameter does not align with the actual cutoff value or the horizontal bar below the knob.
  6. The knob’s response feels non-linear, with disproportionate changes in sound or visual feedback at certain positions.

Occurrence / Frequency

Always

Found in Firmware

  • Version: 1.0.1
  • Build: 1459

Attachments

Maybe it’s related to this problem:

Ja, could be. Behaviours of the pots, what’s written on the screen and what i am listening too, seems off at a couple of places. I think the UI needs a rework or thorough testing. Was wondering why no one of the early adopters / gear tubers mentioned it. Could be me, ofc.

Yeah, that happens, they often don’t dive deep enough, or don’t question things.

While I get your points and mostly agree, I’m not sure this will pass as a bug, as it is probably “working as designed”, although the design could be improved. It might have to be delivered as a Wish instead. Let’s see if we can get an opinion on this from the Polyend Team.