AW: AW: Keyboard/Midi Frontend (RE: PolyModular Standards)

[jh]

>> BTW, there is one truely brilliant feature in some Ensoniq keyboards:
>> You can switch the Pitchbend to only work on notes that are still
>> held on the keyboard (and not sustained by the sustain footswitch).
>> That way you can bend single notes on a chord like guitarists are
>> used to do ...
>
>So we need individual fine tune/pitch bend outputs for every voice (or
>high resolution DAC). Could be used for autotune too. Another missing
>feature...
>
>> One could implement it in the analogue domain easily, given
>> that the Midi interface puts out a separate Sustain signal instead of
>> just prolonging all Gates.
>
[...]
>Ok, we wouldn't need separate fine tune outputs, but we do need fine
>tune on/off switches for each voice instead then.

I'd say all we need is a quad Sample&Hold. (This might even be integrated into
a quad portamento circuit, without using up another OTA / cap / buffer stage.)
Assume you have the Pitchbend added to the KOVs of all voices, but the
gate signals only carry the key-depressed function (with a separate sustain
CV going somewhere else). Put the KOVs into the S&H and the Gates
to the S&H sample input. (A "Track and Hold", actually, i.e. not edge triggered,
that would be.) The voice that has it's gate still on will track the bender,
the other ones won't.
Ok, this is just the first thing that came to mind, and a possible drawback would
be that a note might be stuck "half-bent" when you release a key in the midst
of your wheel operation. This could easily be cured with a separate bend CV (only one for all voices), and a quad transmission gate (rather than track and hold)
controlling whether it's added to a voice or not.
Things like that will not always result exactly in what you'd expect, but they
surely are a source of new or slightly varied functions.
For instance, I never use a Midi Split function anymore when I control the JH-3 from my Kenton Pro-2. You can do nice split fuctions just with a voltage
comparator (monitoring KOV), a little logic on gate signals, and (optionally)
a Sample and Hold. And if you have found the desired function with, say,
the logic in "AND" mode, you might switch that gate to "EXOR" and just see
what happens. Then see how it responds to your playing, adapt your
playing style and you have another source of creativity ...
That's why I want the Keyboard (or Midi) interface to have a lot of generic
outputs, easily switchable, but no real need for more sophisticated functions
in the Interface.

>Unison means: monophonic, but all voices stacked? 

Yes. The other important solo modes, single voices playing at a time,
can be adressed by just switching the other voices off. (And taking them
off the assignment algorithm, as described before.)

>> A little more than that. You also want to remove the disabled voices from
>> the assignment algorithm. It should even be implemented to work as
>> a "Drone Mode", i.e. if you disable a voice for which the key is still held
>> on the keyboard, the gate should be (optionally) kept high, and the last
>> pitch should be kept assigned to that voice. So you can sustain individual
>> notes independently, and also release them independently.
>
>But then you need to know which voice plays which note...

The good old Emu/Obie scanner had an overhad logic and separate
voice logic circuits. A voice logic circuit would give feedback to 
the overhead logic if it is already assigned (or switched off), when
asked about a certain note (adress) it would give feedback if it is
(or was) adressed to this very note. Very clever. I mean it takes some
time to understand it when we look at the circuit *today*, but what
genius did it need to come up with that when there were no other
circuits like that around ! (Deep bow towards pre-sampler Emu ...)

How to do this in software ? Object oriented language ? (I really
don't know, but it just comes to mind when you think of separate
intelligent modules communicating with one another ...)

>"Organ is wonderful easy to play. You press two keys and put a match
>between them and it makes music all night long" (Carla Bley) ;-)

JH. 
(always having a few wooden clothspins at hand for various purpose ...)