[sdiy] About that spherical impulse generator...

[Glen]

There was someone recently talking about building a roughly spherical
shaped speaker array, for the purpose of capturing the impulse response of
an acoustic space. I assume that swept sine waves were going to be played
on the 24 speakers of this array.

What about using a dirac pulse instead? Since the speakers can't follow the
transient of the dirac very well, replace them with a spherical array of
piezoelectric discs. These are cheaper than speakers, have a much better
transient response, and for the short duration of the dirac pulse, could be
driven much harder than they normally would be for a continuous signal. I
believe that someone said that the speaker beaming issue was worse for
larger diameter speakers and higher frequencies. Since these piezo elements
are much smaller than most speakers, you can pack many more of them on the
surface of your approximated sphere, for any given sphere diameter. I would
think this should reduce the beaming problem a great deal. I know, you
probably don't think that piezo discs could generate enough volume, but
keep in mind that there will be MANY of these discs pulsed to their
absolute maximum peak volume, all at the same time. It only has to be loud
for an instant. I think it just might work, at least for smaller spaces,
perhaps not even as small as one would first think.

Does anyone think it's a crazy idea? ...an interesting idea? ...maybe even
a good idea?  :)


later,
Glen Berry