[solved] volume bug after changing amp env sustain level of a held note

[charonme]

when holding a note and changing amp envelope sustain level the virus starts to slowly modulate the volume. Can anyone reproduce it? Example demonstration vid: https://youtu.be/T92OAvfHctg


[edit] partially solved by resetting the virus, but the cause was not found

[Timo]

Anything to do with Sustain Time? Seems the TI doesn't have a dedicated Sustain-Time knob in the ADSR section like the older Indigo, so it'll be in your menus.

Sustain Time is almost like an infinite Sustain Decay after the sustain phase is reached. It's more a 5-point ADSTR envelope rather than the usual ADSR.

If you don't want the modulation, ensure Sustain Time is set to zero.

[Timo]

Actually, sounds like it could be a oscillator phase issue. Are both oscillators enabled and mixed (summed) together?

They're never exactly the same speed, even if Osc2 detune is set to zero, so they will slowly phase in and out when mixed together, almost like a very slow-modulating amplifier LFO.

[Timo]

Just tried on my own Indigo and couldn't replicate the issue. Enabling both oscillators makes it sound phasey, not volume modulated, which figures given they're both the same waveshapes as opposed to inverse waveforms.

Unsure at this point what it could be.

[charonme]

thanks for the replies and the attempt at reproducing it. C126 uses only 1 oscillator (you can see the oscillator balance = -100% at 2:36-2:48 in the vid)

Isn't indigo = virus C? This is about TI2, it has a completely different operating system. TI2 doesn't have sustain time, but it has sustain slope. Around 6:14-7:20 I play around with the sustain slope (I originally had it at 0) and the bug doesn't seem to be related to it.

The slow volume modulation is only triggered when I change the sustain level while a note is held, otherwise it works normally, so it can't be caused by any normal operation

[edit] I checked the C works normally

[charonme]

Access replied that they can't reproduce it and recommended a reset. ​I reset the virus and the bug is gone

[Timo]

Nice one. Strange bug it was, then.