[sdiy] TX81Z, YMxx chips, and aliasing

Michael Zacherl sdiy-mz01 at blauwurf.info
Wed Sep 5 09:14:58 CEST 2018

> On 3 Sep 2018, at 09:43, Declare Update <declareupdate at gmail.com> wrote:
> Do the yamaha FM chips, such as the YM2414 in the TX81Z, do anything toward anti-aliasing? more specifically, does anyone know if they use band limited tables for their extra wave forms besides sine, and is there any attempt to band limit the signal after FM is applied? 

On the bottomline bandlimiting the source wave forms is moot, since it’s the FM’s sidebands which cause the aliasing (and are responsible for the rich spectrum).
So even when using just sine waves you may get side bands which get above Nyquist and/or below zero.

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