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AScustomWorks / AS

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Sawish Oscillator has pronounced DC offset #3

Closed Chaircrusher closed 6 years ago

Chaircrusher commented 6 years ago

This simple oscillator + scope patch demonstrates. Not a huge deal in isolation, but when used with other processing modules (i.e. phaser, reverb, anything with a feedback path) the offset is magnified to the point that the waveform is pushed up against 0DbFS and the sound disappears. AS-Saw-DCOffset.zip

Chaircrusher commented 6 years ago

These two scopes demonstrate the issue (which btw isn't a problem limited to Sawish, it's all over VCV): The Sawish output is assymetric around 0 with mod at the leftmost setting. It becomes more symmetric as you raise the mod level. But the output min/max of Sawish through reverb shows how feedback processing magnifies the DC offset. The AS Phaser plugin also does this (magify DC offset) as-sawish

AScustomWorks commented 6 years ago

Thanks Kent, I added the dc blocker code from Antonio on FB and tweaked the osc code a bit, so this issue is kind of fixed. Using reverb on the signal now doesn't push it too far. To be honest this module was not meant to be taken too serious(nor the original developer code I think hehe), so it is what it is until I get more proficient with dsp stuff. Implemented code will appear on the next release version (0.5.4)

Chaircrusher commented 6 years ago

The thing about this oscillator is that it responds uniquely to mod voltage -- is that some sort of internal waveshaper? I like it and whatever it's based on is decent.

AScustomWorks commented 6 years ago

Indeed it sounds like a waveshaper but can't tell from the code, cos and exp seem to be doing the stuff Btw. I did some more tweaks(yet to be published) as another user found he liked the sound when the dc offset was more present... kind of bring back a bit of the quirkiness without bringing back the dc stuff. So now I declare TinySawish as a permanent work in progress :D