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sah/history disturbs phase, in poly/gen

December 24, 2013 | 2:54 am

there is a rather rambling and opaque version of this problem statement in a related post:

I am restating it here purely for clarity, and not out of impatience or frustration. I wish to create overlapping grain windows, using phasors inside gen~, inside a poly~. This much is trivial. I would also like to vary the frequency of the phasors without interrupting the ramps, but as soon as I add history/delta/sah, the previously immutable phase-offset is disturbed.

Where the input frequency value is not sampled, the phase offsets are fixed, as desired.

The attached simple demo patch illustrates the problem.


– Pasted Max Patch, click to expand. –


Thank you for your patience

December 24, 2013 | 4:06 am

Your gen~ patcher now introduces drifting phase offsets, because you trigger your sah with a phase offset. You would have to trigger your sah without any offset. This causes your 50% out of phase ramp to start its new frequency halfway. But this way your phase offsets stay aligned. Is the mid-ramp interruption very noticeable?


– Pasted Max Patch, click to expand. –


If you want to make sure each ramp is finished and not interrupted halfway you’d have to use oneshot ramps. Just like I proposed in the other thread. But say you go from a 1000ms ramp to a 10ms ramp. Your first phasor (0. phase) has already started with its 10ms ramps, while the other phasor (0.5 phase) is still finishing its 1000ms ramp. This behaviour may be unwanted.

December 24, 2013 | 1:28 pm

Hey, thanks again Dave. I’ll have a deeper look at this, try your suggestions and report back.


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