Possible Unison bug

When using the layers mixer and adding Unison to only one layer, increasing the number of voices will multiply voices on other layers too. I’m not sure if that’s expected behaviour or if there is something missing in my audio path so here is a simple test project if anyone wants to test it:

In this project I have a layers mixer with two layers. Only layer 2 is audible, but if you increase the number of voices on layer 1, layer 2 will get louder. Detune has no effect on layer 2.

here are screenshots of both layers:

Comments

  • I’ve been having similar behaviour when changing voice count but not knowing exactly how they work I assumed it was expected.

    A short written or video tutorial would go a long way.

  • Wow that's a weird one.

    Another oddity I've just found is that disabling the MIDI to CV module has no effect.

  • I have a rack with 16 Flexi samplers each in their own layer with their own MIDI to CV module. Yesterday I found that adjusting the voice count in one layer affected the volume of the sample in another. I suspected this wasn’t expected behaviour but wasn’t sure but could be related to this.

  • The situation:

    There is a mixer with 2 inputs A & B, A gets signal that consists of 8 voices, B of just one voice.

    What should mixer do? :)

    I decided not to downgrade output signal and output 8 voices (max number of voices available on inputs).

    But each voice on output is a mix of A (8 voices) and B (1 voice), so this single voice from B is mixed into each voice of A, hence increased loundness.

    Its like before mixing the polyphony on each input is increased to the biggest value. I think this behaviour is the most logical.


    There are many modules with built in mixers, layers is one of them.


    The solution:

    Use Poly to Mono module at the end of unisono path.

  • Thanks for the explanation and solution, it works perfectly!

  • @giku How would the average user know without your help?

    That behavior might be logical from developers' eyes but certainly not for people with experience in (analog) modulars.

    A long time ago we've talked about some kind of monitoring/debugging utility to get a better picture of what's going on at what point in the signal path. Currently there is no hint whatsoever and I would have expected the mixer "to know" where the signal on a certain input channel is coming from, just like other modules do, and treat the unisono path accordingly.

  • edited February 17

    Yes this needs to be covered in docs.. and will be soon I hope so

    As about "treating the unisono path accordingly" - what is accordingly? :)

    I've been thinking about a system of alerts .

  • edited February 17

    I think we need Unisono rack module :) - a solver

  • @giku With "accordingly" I mean that Drambo already knows that voice count on layer 2 = 1. Unlike on analog gear, the respective mixer channel can be aware of that fact.

    Or, in your words: Don't mix a single voice into 8 voices but mix them separately (voice sub mixes into final layer mix, so to say).

    Would there be any disadvantage to that?

  • edited February 17

    Mixer already knows that and decides to mix B into each voice of A. Other strategies like: decrease number of voices are worse, because they don't let you choice. (now I can use poly to mono module to select behaviour. I can imagine a need of any of them. )

    This logic is present in every aspect of D.. e.g. You modulate polyphonic module with 1 voice LFO..

    So 2 rules:

    • Drambo always respects voices during mixing, never decreases them
    • In case of missing voices, existing will be multiplied (the same applies to mono -> stereo)
  • edited February 17

    @giku By "multiplied", you mean phase coherent summing resulting in a simple boost?

  • Sounds like a new chapter in the Drambo Wiki 😁

  • BTW how do I know what the different racks do to my signals?

  • edited February 17

    In the past I've used a unison module infront of a rack and noticed the output volume goes heavily into the red. Does this mean I was using unison on a patch that doesn't support the polyphony correctly? I feel like whenever I use unison I have to manually attenuate the gain.

  • edited February 17

    @quartzite

    unisono is expected to rise the volume because u are doublicating voices

    per voice it should rise about 6db because u play more or less the same thing twice

    (play a snare on track one , play same snare on track two, output of both together plus 6db)

  • edited February 17

    Yea that makes sense. I do honestly wish it was able to handle the gainstaging itself, but as a module that doesn't seems doable. But maybe if we get a unison rack maybe it it can do some auto-magic 🧙‍♂️

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