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Originally Posted by dale116dot7  I've done my LFO's on the host, though I plan on moving that over to the DSP when I get around to it. I did it on the host because it was just faster for me to write it that way. The only problem I have with that approach is that for a single chorus, the update rate is fine, when you have half a dozen of them, I can only update them at about 2kHz or so - and at high chorus rates, you get modulation noise at that frequency. |
Is this due to the inability to update x and (1-x) at the same time, or due to quantization of the modulation signal? I used to perform chorusing at 1/10 to 1/16th of the sample rate, and it sounded fine. However, maybe my ears weren't as good. If the problem is due to sync errors with the 2 linear interpolation coefficients, a few ideas:
- Calculate x on the microcontroller, and 1-x on the DSP. It will take an additional cycle or two per interpolation, but it might fix the problems.
- Use 1st order allpass interpolation. This works with a single coefficient - read Dattorro pt. 2 for details. Sounds nice for reverb modulation, not good for pitch shifting.
Sean