Ableton: Understanding Analog's "Uni"

Question

Pre-Question-Introduction: I am a noob, but I really want to understand what exactly is going on behind every single dial and button I press.

The "Uni" button on the Analog module of Ableton live, which stands for "Unison," creates a second voice. The pitch of that additional voice depends on the value of "detune."

I'm trying to understand what exactly this means. To do so I am starting with the most simple inputs as possible. These questions assume one sine wave oscillator, and an amp at a constant 100%

My questions:

1. The value of Detune ranges from 0 to 100; what are the units here? What is 0 and what is 100?
2. Using a sine wave and 2 voices creates a rhythmic silence and pause which is more noticeable for smaller values of detune. Am I correct that this is a manifestation of beat frequency? Can I control this effect or is that pulse just a fact of life?
3. I am able to increase the number of voices from 2 to 4. What is actually happening here, what determines the pitch of those four voices?
4. I noticed that the effect of Uni changes depending on when I enable it (try spamming a note and rapidly turning uni, with detune set to 0, on and off). It seems the phase of the second voice can shift around resulting in different types of interference. What determines the phase of the second voice in relation to the first? Is there a way to predictively enable it?

Thanks for helping a control freak understand the tool.

Answer 1

I have done some digging and experimenting, and will hopefully even hear back from members of the Ableton community soon, here are the answers I've found so far:

1: What is the scale of "Detune"?

This value is some type of percentage, where 0 is the tone being played, and 100 is one octave above that tone. But it doesn't seem to be linear. 75 is a whole tone, 65 seems to be a semitone, and less than 65 is in between the original tone and the semitone. I'm still curious what the exact formula is here.

2: Is the "pulse" an example of beat frequency?

This is, indeed, a manifestation of beat frequency. From what I understand this is a fact of life (and one that affects more than the Uni button)

3: What determines the tone of the four voices?

To figure this one out I used the "delay" setting. By setting the delay to the maximum value (100ms) I delay the entry each voice by 100ms, in sequence. this means the first voice comes instantly, the second after 100ms, the third after 200ms, the fourth after 300ms. With this setting, if you play a note for less than 100ms you can hear the notes independently.

• Voice 1 is the original tone
• Voice 2 is voice 1, shifted up by one "detune" unit (i.e. if detune is 100, 1 octive)
• Voice 3 is voice 1, shifted down by one "detune" unit
• Voice 4 is voice 2, shifted up by one "detune" unit

This means if detune is set to 75 (which is a whole tone) and you play a "G" the four voices, in order would be: G, A, F, B

4: Why does rapidly clicking a note + "Uni" with a detune of 0 result in unpredictable sounds?

I'm starting to think this is just a bug. I will report back if I learn otherwise from the Ableton community.

Answer 2

It's a mix of your input sine wave and a delayed version of the s wave. Eventually the two s waves add negatively and there is a brief cancellation of each other resulting in the short silent period. The smaller the detune value is means that they tend to remain antiphase (and cancelling) for a longer period of time BUT it happens less frequently.

The 100% detune value might be one semitone but I'm not sure.

Keep testing with s waves because that's the only way you'll get to the bottom of this.