Zebra: why is the sound of my patch out of tune when the modwheel is down?

[Mr Greg G]

I have this patch I made from scratch with just 2 OSC (actually 1 OSC duplicated 1 oct down) going into 2 VCF (same here, 1 is duplicated) and 1 ENV. My goal was to reproduce a basic TB-303 type of sound with a delay.

Everything looks and sounds good until I turn the modwheel down to close the filter. The sound becomes out of tune and I can't figure out why. As you can see on this screenshot, detune is set to 0. And the only things the modwheel controls are the 2 VCF modules. I have been pulling my hair on this one toying with many parameters but can't figure out why this happens.

Do you have any idea why? I can upload the patch if anybody wants to look further into this.

Click to read more...

 

[Living Fossil]

Have you looked if there is something going on in the "matrix" menu?

p.s. and uploading the sound would maybe be helpful

 

[Mr Greg G]

Have you looked if there is something going on in the "matrix" menu?

p.s. and uploading the sound would maybe be helpful

Nothing in the Matrix menu.
Sure, here is the preset, thank you

 

[pocvecem]

Nothing wrong with your patch. That's a normal behaviour. Also nothing special with Zebra. Almost any lowpassfilter will do that "special thing" because of non-linear phase responses from the filter.

When the cutoff frequency is static everything sounds right. But when you move e.g. the cutoff frequency down the phase response of the filter also moves with it and then you get the effect of pitch going down also.

 

[Pier]

Seems to be the glide parameter accentuated with the delays on top of each note. Also some phase fuckery.

If you disable glide and enable phase reset the effect is gone.