Emulating chips vs using algorithim in chips?

Andrew C
2009-07-29
2013-05-23
  • Andrew C
    Andrew C
    2009-07-29

    Nick,

    Just wondering, is there any advantage to emulating a digital chip (for example a SID or YAMAHA) vs just implementing the algorithim of the chip?

    I mention this, because a guy on KVR said that the bristol SIDney sounds more like a SID than the quadra-SID(a popular SID synth).

    Andrew.

     
    • Nick Copeland
      Nick Copeland
      2009-07-29

      Wow, sounds better! That pleases me a mountain. Not sure which emulation method it better and since I don't know how the quadra-sid operates then I don't know how to answer. The digital part of the chip probably would not sound different whether the chip was digitised or emulated, as long as the generation method was the same the results would be similar. The Bristol SID did attempt to put some of the grunge into the sound with chip noise and oscillator leakage (the latter came from analogue imperfections of the chip conversion that might not appear in a digitised chip).

      The analogue part of the chip, the filter, is where a lot of the warmth comes from and I used a pretty hefty algorithm here, not mine, its a modified houvilainen filter. The mod is potentially quite reminiscent of the SID though: it had a 12dB/Octave filter, this mod works on a 24dB/Octave filter but mixes back the 12dB and 18dB poles, that adds color to the signal and brings back the 12dB characteristics. Now perhaps the reason this is close to the original is that it also tended to have unique results based on the fabrication process and quality of the offboard capacitors that were required as they could not be implemented on-chip for the SID. Different fab runs actually gave the original different qualities. Mabe the bristol SID introduction of a few unpredictable signal processing methods give it a bit less of a digital feel.

      kind regards, nick.