| Turns out that my left allpasses are shorter than my right allpasses. I'll try reversing the sizes.
I'm not so sure that the 'choppiness' isn't actually some amplitude variation through the loops that sort of wavers gently at large sizes, but then gets faster - and more noticeable - at smaller sizes. It happens with or without loop allpasses, and it comes on gradually with size reductions. That would indicate either my output tap gain or loop gain tuning needs a bit of work. Since I use an algorithm to calculate that out, that probably needs some work. It also gets better at extremely long RT's and worse at shorter RT's, so it seems as though it's in the feedback path, which is pretty simple - three gain multipliers. I should check the calculations on those feedback path numbers.
I'll run some more rough mixes through once I get the remaining problems fixed. The combing is gone, I must have had a programming mistake because when I split the algorithm up into the two chips, I needed to change about four lines to transfer the raw tap data from one chip to the other. The problem went away as soon as I did that, so I probably had one instruction in the output tap section that didn't clear the accumulator when I expected it to be zero. |