[sdiy] Dealing with velocity sensitivity / scaling on envelopes

[Mattias Rickardsson]

On 4 September 2017 at 13:44, Joel B <onephatcat at earthlink.net> wrote:
> Wouldn't you just give each timbre its own fixed voice allocation and only steal within that timbre?

No, that makes the synth much more limited. (But I guess most makers would.)

Also, changing sounds (timbres, "presets") between notes is a case
similar to voice stealing between timbres, even for a synth without
either voice stealing or multitimbrality. A new sound is suddenly
played with the voice - and what should happen then?

/mr


> The old Kawai k5, Casio CZ, Cheetah MS6 work like that although the K5 has a VR mode where it will share voices between timbres, usually if I recall correctly the timbre changes and the envelope continues on as it was rather than re-trigger. The stealing effect is its own unique and rather cool sound imo.
>
> Joel
>
>
>
>> On Sep 1, 2017, at 9:43 AM, Mattias Rickardsson <mr at analogue.org> wrote:
>>
>>> On 1 September 2017 at 15:13, Oakley Sound <oakleysound at btinternet.com> wrote:
>>>
>>>> RTZ ADSRs have their place....
>>>
>>> In the bin. :-)
>>
>> Not if you're designing polyphonic multitimbral voice-stealing
>> analogue synths! ;-)
>>
>> This is a very tricky situation, and although I agree that the
>> envelope should model a capacitor charging/discharging - and that the
>> velocity factor should generally act as a multiplier on the resulting
>> envelope rather than changing the envelope internally - and that the
>> nasty clicks potentially introduced by RTZ can be hopelessly
>> problematic, I clearly see the need of RTZ if there is a risk that the
>> synth voice is doing something unknown and irrelevant before the note
>> that is to be played. Starting the envelope from random values will
>> ruin the sound to some extent, and this is what can happen if the
>> voice is used for different timbres and/or sent to different outputs
>> on consecutive notes.
>>
>> Depending on your application, Tom, you might or might not need RTZ,
>> but even without RTZ the velocity scaling could give you nasty
>> clicks... so it's not easy! I'm even thinking that a zero-crossing
>> detector would be useful in order to minimize those clicks when
>> changing velocity, but that's perhaps the topic of another luxury
>> discussion. :-)
>>
>> /mr
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