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Additive Synth/Audio analyser phase issues

January 14, 2013 | 4:38 am

I’m building an audio waveform analyser with an 8 sine wave additive synth. Basically I’m showing how waveforms change as you add or remove partials. I’m using a dictionary to store frequency multipliers and levels for the oscillators, and that side of things seems to be working fine.

The problem occurs when I recall a particular setting from the dictionary; the levels and frequencies are set, but the phase of the cycle~ objects seems to shift, as the output on the scope isn’t what I’d expect to see. Turning DSP off then on again fixes the issue, but I don’t know what the root of it is. Can anyone help me?

– Pasted Max Patch, click to expand. –

January 14, 2013 | 3:28 pm

I’ve tried resetting the phase of each cycle~ object to 0, but this doesn’t fix the problem. Any ideas?


January 14, 2013 | 6:43 pm

If you want to make sure a bunch of cycle~s stay in phase, drive them from a single phasor~ using rate~.
You may also want to look at controlling the relative phases of the sinusoids – at the moment you’re just adding them all in phase, but reversing the phase of a component can radically change the sound, and indeed is necessary for building things like square waves,
Cheers
Roger


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