Dixie II+ Sync Behavior

I have a Dixie II+ and I don’t fully understand how the sync works on the Ramp and Square waves.

For Sine & Triangle, the sync resets their waves to zero and starts in sync as you would expect. However for the Ramp and Square waves they do re-sync, but not from zero.

I’ve attached 2 images to show you what I mean.

Sine (good)

Ramp (odd)

This means I couldn’t use the Ramp wave as a decaying envelope as it doesn’t start in sync. I have 2x Dixie II+'s and this is the behavior on both.

Looking at the Dixie II+ webpage it says…
“Reset to 0 V hard sync input, ideal for percussive sounds or modulation.”

And in the manual for the Sync input…
“When the input waveform crosses zero the oscillator is also reset to zero.”

This isn’t what is happening however? :thinking:

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The Dixie is a triangle core VCO which means if you are doing a hard sync reset then it is going to be relative to this shape. Most triangle core VCOs will reset to -5V starting point but we specifically designed the Dixie to reset at zero. The reason for this is so that if you are using the sinewave or triangle as your waveform for a percussive sound (e.g. a kick drum) then you can patch the same trigger that is used for the modulation envelope (e,g, to sweep pitch and VCA) to the hard sync input so that your waveform starts at zero and there is no click.

The sine waveform is shaped directly off the triangle and so they both appear to reset at the same point.

The saw waveform is made from flipping and shifting half of the triangle waveform so its shape is going to be different if you have reset the triangle core.

If you had a saw core vco it would be a different story.


Thanks for such a clear, and enlightening answer. Super useful and good to know.

Appreciated. :kissing_closed_eyes:

[Edit: I renamed the thread to be more useful in the future.]