Re: On 8 speakers

Subject: Re: On 8 speakers
From: Chris Rolfe (
Date: Sat Jan 30 1999 - 03:24:00 EST

Hi Kevin,

        As the sometimes sorry translator between music diffusion and
theatrical show-control methodologies, I have to say that ALL interfaces
close off possibilities. Nonetheless, I'm developing a great deal of
respect for the theatrical show-control conventions. They're low-level, but
often just what a sound-designer needs :-)

        One approach to your suggestion comes from theatre. A lot of
show-control involves +/- setting commands, as with submastering. The
concept is simple, take the existing state of a controller and de/increase

        The AudioBox (which is the hardware my software likes to control),
has assignable submasters, which means that you can program the mixer to
accept MIDI continuous-controller commands to adjust any level within the
mixer (input, output, assign/crosspoint) by a RELATIVE amount (ie, +3 dB).

        What you describe is, therefore, tricky but do-able.

        The job of the software designer is to spare the neophyte user from
details, but allow the pro-user to do everything feasible. Recording mixer
moves (available as MIDI info from many mixers, and certainly from JLCooper
fader packs or Mackie's HUD), would be a great addition to the program

        I DID implement a MIDI controller scheme recently. I made it for
Matt Rogalsky at a Vancouver gig, but he didn't use it in the end. I,
however, used it to crank out my diffusion score in a few hours instead of
the usual three days (programmers should avoid being on the concert bill,
however, for the simple reason that they are torn between the program's
performance, and their own performance).

        I've also got a controller recording scheme, but haven't reconciled
it yet with both the theatre and music models. I'm working on it as we



>Chris continued:
>>From: Chris Rolfe <>
>>Subject: Re: On 8 speakers
>>The diffusion controller is also interesting. In addition to specifying
>>angle and magnitude (independent of speaker location), the user specifies a
>>diffusion width, that is, send input 1 to all speakers between 0 degrees to
>>90 degrees.
>> x
>> x | x
>>x |__ x
>> x x
>> x
>Is it possible to input this information in a kinetic fashion, such as
>with a 'MIDI mixer console' (like the Mackie), so as to also take
>advantage of the kinteic aspect of live projection?
>Frequently, to 'draw out' an aspect of a sound, a 'pulsing technique' is
>employed. (Easier to see than describe.) For example, imagine a sound
>complex where there is a mid-frequency beating inside a complex,
>transforming sound.
>The fingers are on faders:
> Left 5 4 3 2 2 3 4 5 Right
>and to highlight this aspect of the sound, fingers 3 and 4 of each hand
>create small amplitude bursts (by moving up and down about 1-2 cm), in
>time with the mid-frequency beating.
>In terms of angle and magnitude, this may be difficult to explain in a
>graphic, but easy to do in a kinetic sense. A code listing could look
>something like: [Time runs from top to bottom (event list format), the
>speakers are in columns, and the numbers represent (some arbitrary) level]
> SPEAKER (L) 5 4 3 2 2 3 4 5 (R)
> 10 10 10 10 10 10 10 10
> 10 12 12 10 10 12 12 10
> 10 10 10 10 10 10 10 10
> 10 12 12 10 10 12 12 10
> 10 10 10 10 10 10 10 10
>The finger movement 'pulsing' is refelected in the level shift from
>While it might appear that such a subtle change (esp given that eight
>speakers are up) might be difficult to perceive, it is my experience that
>because the amplitude shifts are synchronous with a spectral change, they
>are perceived quite clearly.
>>I think the diffusion controller illustrates the limitations of a strict
>>spatial model. What would be the xy equivalent of a 360 degree (diffusion)
>>assign? If I had a global reverb return to the mixer I would assign it to
>>all speakers, but by no means imply an xy position.
>Possibly this would be an advantage of a mixer-based kinetic input as an
>addition to the system.
>> And aware that each decision might close down
>>a valid sound-reinforcement technique.
>Agreed! which is why I ask about having a MIDI-mixer interface in
>addition to the graphic one. How difficult would it be to implement?

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