SID chip noise parameter?

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Andrew C
2009-05-14
2013-05-23
  • 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?

    Andrew.

     
    • 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

       

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