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Feature requests: "real" envelopes, and PWM

RevokRevok
edited March 2015 in General
Hi Julian,

Sorry if this has been brought up before.

While working with the LXR today I thought it would be great to have several independent full ADSR envelopes on each voice which can be routed freely to FM, filter or both. Applying envelopes to the separate FM parameters would really open up a world of extra possibilities, I imagine. I often turn to my Yamaha DX21 FM synth for percussive sounds, and it's really all the discrete envelopes that give the synth that twang!.

I was also wondering if PWM is at all possible on the LXR? Perhaps I haven't delved deep enough to find it, but some way of modulating the pulse width of the square wave could be a very inspiring addition as well.

Just dreaming out loud here :)

Take care!

Revok

Comments

  • brendanclarkebrendanclarke
    Envelopes got discussed a bit here:
    http://forum.sonic-potions.com/discussion/comment/6492#Comment_6492

    The main reason this hasn't been added, I think, is that adding kit parameters is fairly difficult, compared to adding global parameters. It means expanding the kit file format, which brings a host of problems. It's certainly not impossible to do, just that no one has had the time to take it on. If someone did, I'd recommend the following method:

    Instead of introducing any new parameters, use the LFO params that are already there, but add a different way of interpreting them so that the values for 'rate', 'wave shape', 'retrig voice', and 'retrig phase' get assigned to ADSR. There would need to be a way of switching between normal LFO and ADSR modes, but there should be some unused values in those 4 params that can get you there.

    PWM is more interesting. Again, I think the trick is using the extant parameters - maybe a new waveshape that has PWM instead of fine tuning?

    I haven't messed with the DSP side of things, but if you want some more envelope control, there are some tricks in my custom firmware. There are a lot of additions, but one of the last ones I did is if you set a step's velocity to 0, it does not retrigger the voice. So, you can, for example trigger a note, then set 'decay' to a very long value on a subsequent step to give 'sustain', and then reset it to go to the release portion. It was a very simple addition, but opened up a lot of very powerful sound shaping options for me. My last build and notes are here:
    http://brendanclarke.com/files/LXR/

  • julianjulian
    adding new parameters to the voices is not that difficult.

    the main reason I ommited the sustain so far is that the LXR was always more intended as a drum module where the sounds are triggered instead of a synth module were sounds are played with a keyboard. So there was no gate length information in the sequencer to be used by a sustain stage in the envelope.

    PWM should be possible. It can be generated by mixing 2 saw oscs together with different offset. has to be done in code but is not hard in general. I noted it for a future update. Some sweet SID PWM could indeed be a good addition...
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