Possible bug: Quadravox -4th inconsistent with pentatonic scale

[jaakjensen]

Hey Eventide Support,

I’m using Quadravox as a harmonizer with the key set to E♭ and the scale set to Pentatonic Major. Voice 1 is set to -4th, Pitch Tracking is on, and Cents is set to 0. I’ve attached a screenshot of the settings.

My understanding is that E♭ major pentatonic contains: E♭, F, G, B♭, and C.

I’m seeing behavior that seems inconsistent when playing notes that are outside the selected pentatonic scale. For example:

Playing A♭ produces E
Playing D produces A
Neither E nor A is in E♭ major pentatonic. More importantly, these two results do not appear to use the same interval behavior:

A♭ → E is a major third down
D → A is a perfect fourth down
Since the voice is set to -4th, I would expect the plugin to either produce a consistent fourth relationship, quantize the output to the selected scale, or clearly document how it handles input notes that fall outside the selected scale. Right now the behavior appears inconsistent, and I do not see this edge case explained in the manual.

Can you clarify how Quadravox calculates diatonic intervals when the input pitch is not a member of the selected scale? Is this expected behavior, or could this be a bug in the pentatonic scale interval mapping?

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[mcasen]

Hi jaakjensen,

This is due to playing non-scale tones, which Quadravox does not support. There is not any expected behavior we can point to for this reason. When you set Quadravox to a pentatonic scale with Pitch Tracking enabled and then play notes outside of that scale the algorithm makes a decision regarding what to play based on the chosen scale rather than maintaining the direct interval relationship as it does when you play a note within the scale.

We do hope to add support for this in a future software product, and we currently offer key quantization in a number of hardware algorithms, specifically Diatonic, Quadravox, Quadravox+, VocalShift and VocalTune.

[jaakjensen]

“the algorithm makes a decision regarding what to play based on the chosen scale”

If it makes a decision, then why does it choose notes that aren’t in the scale? Seems strange. I would expect a diatonic pitch shifter to force out of scale notes into the scale.

“we currently offer key quantization in a number of hardware algorithms, specifically Diatonic, Quadravox, Quadravox+, VocalShift and VocalTune.”

So does that mean there are other devices that support this? Like if I picked up an H90 or H9 I could run one of those and achieve the effect I’m seeking?

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