SID chip noise parameter?

Andrew C
  • Andrew C

    Andrew C - 2009-05-14

    The website for the SIDney says that "The emulator provides some control over the 'analogue' section. The S/N ratio
    can be configured from inaudible (just used to prevent denormal of the filter)
    up to irritating levels. Oscillator leakage is configurable from none up to
    audible levels"

    Do I have to edit this at code level or is it not implemented yet?


    • Nick Copeland

      Nick Copeland - 2009-05-14

      Ah, no, this is not a visible parameter. The softSID provides a parameter that is the S/N ratio, it is basically leakage into the filter. The filter is always given an amount of noise which should be below an audible threshold to prevent it going to 100% with zero input - denormal. This noise injection level is configurable but only with a compiler.

      The default value is empirical which just means I configured a level that for me was 'just' audible. The next version of a bristol softSID synth will give access to this.

      To be complete, there are the following parameters that the chip accepts but that the GUI does no provide access:

      S/N ratio: filter noise level
      Leakage: oscillator leakage level into the filters.

      DC Bias: nominal DC signal level
      Volume: output signal gain
      Clock rate: the rate of the nominal clock (this was a bug fix for your tuning issue).
      Detune: applies adjustments to waveforms in Multi mode.

      So in short, to answer your question, yes, most of this stuff is only configurable at the code level.

      Regards, Nick


Get latest updates about Open Source Projects, Conferences and News.

Sign up for the SourceForge newsletter:

No, thanks