Hi folks, according to my calculations, the number of BBD stages is related to the highest possible musical note via karplus strong synthesis as follows: 128max=G5 256max=G4 512max=G3 1024max=G2 2048max=G1 4096max=G0 Am I wrong? Here's how I got there: 1) the frequency of the karplus strong loop is the note that will be heard as the loop attenuates. This frequency F is equal to F = Fs/N where Fs is the sampling rate and N is the number of samples. 2) According to the Doepfer documentation for the A-188-1, the design clock range of these modules is roughly 10kHz to 100kHz. I am assuming this is the range of acceptable values for Fs. So taking Fs as 100kHz, and N=128 (for the 128 stage BBD), the highest note that this setup can play is 100000Hz/128 = 781Hz or roughly a G5. The lowest note is not so much an issue, but just for grins, 10000Hz/128= 78Hz, or roughly D#2. 3) For comparison, the 256 stage BBD will only manage 100000/256 = 390Hz, or about a G4. And it goes down an octave with each doubling of the number of stages. Since it appears that my guitar roughly covers octaves 1 through 4 (I think) the 256 BBD is the ideal number of stages for plucked string sounds. Any advice is appreciated, especially from those who have tried BBD modules. Thanks, Doug
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karplus strong mathematics and the A-188-1
2008-04-30 by Doug
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