What is the “phase response” of a sine wave? (Zebra 2 Osc FX)

[Gone soft]

I'm a bit puzzled by what the difference is between Osc FX “Phase Xfer” and “Phase Root” in Zebra 2. And how do those compare to “Trajector”? I can hear that they certainly sound a bit different, but in choosing between them I often make semirandom decisions and then finetune whichever I've chosen. I get how “Trajector” works, I've got a bit of experience with phase modulation but I haven't seen it being explained in terms of “phase response”.

Oh, should mention I'm not particularly knowledgable about mathematical terms sometimes used to describe what synthesis techniques does. Stuff like pictures showing how different waveforms are altered along with a few well chosen words tend to make sense to me. I've been exploring a bit with an oscilloscope plugin, but I haven't been able to make complete sense of what I'm seeing here yet...

Phase Xfer
A variant of PD (phase distortion) synthesis. The original waveform is not output directly, but is used as the phase response of an extra sine wave – which you can hear when the value is zero.
Phase Root
The original wave multiplies the phase response of the sine wave.
Trajector
The original wave adds to the phase response of the sine wave. Like phase modulation in ‘FM’ synthesizers – try Trajector on a pure sine.

[moscom_electronics]

I hope that what I will tell you is clear. When the guys at u-He tell you that the wave is used to control the phase response of the sine wave, it is another wave to tell you that you control the speed at which time goes for the sine wave.

In other words, say you have a value to which you add 1, every second. If you use this value to compute the value of the sine, you will get... a regular sine. But now, imagine that you still add one to the counter, but that the time between each step changes (for example, the time between the first and second step is 1 second, then 2 s between the second and third steps, etc...). If you compute the sine, you will get a distorded sine wave whose values won't be sprea evenly but at varying times.

Practically, this means that the wave you for phase xfer in zebra is used to modify how the time used to compute the sine wave flows.

Cheers

[Gone soft]

I hope that what I will tell you is clear. When the guys at u-He tell you that the wave is used to control the phase response of the sine wave, it is another wave to tell you that you control the speed at which time goes for the sine wave.

In other words, say you have a value to which you add 1, every second. If you use this value to compute the value of the sine, you will get... a regular sine. But now, imagine that you still add one to the counter, but that the time between each step changes (for example, the time between the first and second step is 1 second, then 2 s between the second and third steps, etc...). If you compute the sine, you will get a distorded sine wave whose values won't be sprea evenly but at varying times.

Practically, this means that the wave you for phase xfer in zebra is used to modify how the time used to compute the sine wave flows.

Cheers

Thanks for your reply. What you wrote is a bit unclear to me, it almost seems as a sort of explanation of FM but I'm not 100 % sure what to make of it with the timesteps of different lengths etc. And is that sine like a free running oscillator in there or will its phase be reset for every new cycle of the modulating waveform?

I'm also still not sure what the difference is between a waveform used as the phase response for a sine as opposed to it multiplying the phase response of a sine. I'll appreciate any help in making this clearer to me.

[Unaspected]

Not owning those synths but knowing synthesis well, it sounds like you're talking about phase modulation? Where one waveform is used to read a lookup table containing another, thus distorting the carrier. Similar to FM, as you say but instead of pitch, it is the phase that is modulated.

A standard digital oscillator or phase accumulator is generally ramping up from 0 to 1 at a set frequency based on the sampling rate of the system. If you multiply that value by the size of an array and use it to read through, your ramp has now become whatever shape the array contained. Now if you distort the ramp, you change how the table is read.

[exmatproton]

Not owning those synths but knowing synthesis well, it sounds like you're talking about phase modulation? Where one waveform is used to read a lookup table containing another, thus distorting the carrier. Similar to FM, as you say but instead of pitch, it is the phase that is modulated.

A standard digital oscillator or phase accumulator is generally ramping up from 0 to 1 at a set frequency based on the sampling rate of the system. If you multiply that value by the size of an array and use it to read through, your ramp has now become whatever shape the array contained. Now if you distort the ramp, you change how the table is read.

Wasn't he talking about phase distortion?

[Unaspected]

Not owning those synths but knowing synthesis well, it sounds like you're talking about phase modulation? Where one waveform is used to read a lookup table containing another, thus distorting the carrier. Similar to FM, as you say but instead of pitch, it is the phase that is modulated.

A standard digital oscillator or phase accumulator is generally ramping up from 0 to 1 at a set frequency based on the sampling rate of the system. If you multiply that value by the size of an array and use it to read through, your ramp has now become whatever shape the array contained. Now if you distort the ramp, you change how the table is read.

Wasn't he talking about phase distortion?

Phase Xfer
A variant of PD (phase distortion) synthesis. The original waveform is not output directly, but is used as the phase response of an extra sine wave – which you can hear when the value is zero.
Phase Root
The original wave multiplies the phase response of the sine wave.
Trajector
The original wave adds to the phase response of the sine wave. Like phase modulation in ‘FM’ synthesizers – try Trajector on a pure sine.

I missed the quote at the bottom of the OP's post.

Essentially as I described though I would just call it PM.

[moscom_electronics]

I agree with Unaspected who gave a probably clearer explanantion of PD and PM.