I think that it makes sense to set the roll off frequency close to the maximum achievable nyquist frequency in order to get rid of any aliasing induced harmonics in frequencies higher than the nyquist frequency. Any frequencies beyond that point shouldn't be there for whatever reason.exxos wrote: ↑Mon Oct 22, 2018 2:24 pmThe "stair step" isn't relating to the filter clock exactly.. the stair step steps will be smaller the higher the frequency is.. I don't know how it would clean that up exactly, some inherent smoothing somewhere. Sample playback speed is the stair step part, the clock to the filter sets the roll off frequency... different things.. Really the roll off is to remove the HF content which can burn up op-amps or even speakers, add bad harmonics etc, so its filtered out.
I would still suggest you bypass the MF4 and see how it affects things.. we have to start somewhere..
Here's another quote that suggest that FCLK is not fixed:
The new GST MCU provides all the frequencies previously delivered by the GLUE and the MMU. However the new shifter (GST SHIFTER see figure 2) receives an 8MHz clock coming from a separate oscillator. This clock called SCLK (Sound Clock) allows, via some internal dividers of the GST Shifter, to generate a clock with an ajustable frequency (FCLK). This clock is used for the sound filters.