Re: [LAD] A Cathedral in your backyard

On Wed, 2007-04-25 at 10:02 +0200, Fons Adriaensen wrote:
> On Wed, Apr 25, 2007 at 09:15:35AM +0200, Jens M Andreasen wrote:
>
> > What I think would be possible as an experiment though (without
> > involving a budget the size of the Pope or TU-Berlin), is to place a
> > large amount of uniform speakers in a circle and then feed them with the
> > same monophonic signal. If everything works as expected, it should then
> > appear like the sound emerges from the center of the circular array of
> > speakers.
> > ...
> > Would that work?
>
> It probably would, *if* you can get all speakers to be exactly in phase
> over the entire frequency band. This will be difficult at HF, and having
> part of the range not focused will destroy the effect and identify the
> radios as the source of the sound.

First problem would be that there is no guarantee that all devices would
agree on that a positive signal indicates pressure and the speaker
should move outwards. There is a good probability though that it will be
that way.

Second problem, as you say, to control the entire frequency band:

That is not possible with random equipment, therefore I suggest to
carefully choose a bandwith limited signal. For instance; we have here,
at certain times, a female voice on the radio giving us detailed
information of wind and pressure all along the coast. It lasts for a
while ... Those devices that have a treble or tone control could be set
to a minimum to focus on frequency band around 1K.

>
> You don't even need a full circle or sphere. I'm currently involved in
> a project using an array of 228 speakers / 64 channels suspended as a 3m
> diameter 'chandelier' from the ceiling. It will create sound sources moving
> above and around the listener's head.
>
Right, I was getting in that direction as well. Still thinking about
swayed arrays of standard signals (as in CD:s or FM-stereo.) for unusual
sound experinces in otherwise bland environments.
I also came to think of closing "the gap in the middle" by having two
swayed arrays of left respectively right creating a virtual center
channel slightly in front of both.Then the focus would be on the lead
singer rather than the little mandolins left and right. Perhaps a
variation on a Phillips array(sp?) could be useful here:

L-R, L, L+R, R, R-L

/jens

>
> FA
>
> Follie! Follie! Delirio vano è questo !
>
>
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