From: Bret <>
>
> Regarding the USACERL paper discussing flat reflectors, he says that
> the logical position for the transducer in such an arrangement would be
> directly on the reflecor surface, as the sound pressure at that point
> is double the pressure in teh incident wave. That sounds rather like a
> boundary mic to me. Is there some other difference between what he is
> talking about and the SASS method that I don't understand?
> bret
If it's the same as a boundary mic, then why didn't Swenson reference it
and discuss the literature? Or is he completely unfamiliar with the
type? If it's the same, his discussion is seriously incomplete.
He not only says what you reference, but illustrates it with a polar
plot. If you think he's talking about the same thing and the SASS is the
same thing you may get quite a shock if you go to Crown's site and look
at the polar plot for the SASS.
Realize, of course, that's Crown's complete model, it's possible the
modified SASS as Lang perfected it is somewhat different. Though in
panning the SASS across a awful lot of soundfields I'd say not by much
if any. I did, when I first copied Lang's design machine the parts to
make my SASS PZM, and tried it both PZM and boundary. When I could find
no discernible difference I dropped making it PZM. Lang is the expert on
the qualities of the design, I'm just a recent convert.
Lang, do you feel the polar plot (figure 5) in Swenson's paper:
http://naturerecordist.home.mindspring.com/pat_mike.post.pdf
Or the polar plot provided by Crown in it's SASS documentation:
http://www.crownaudio.com/pdf/mics/126982.pdf
More correctly represent the Modified SASS design we use? Or represent
any aspect of it at all?
If you wish to understand real boundary mics, not a piece of pressboard
with a electret capsule somewhere at the surface, I'd also suggest you
start by reading Crown's Boundary mic guide as a introduction, also read
through all the issues of Crown's Mic Memo newsletter to understand the
history a bit better, then look up the published papers on these
microphones.
Walt
________________________________________________________________________
________________________________________________________________________
"Microphones are not ears,
Loudspeakers are not birds,
A listening room is not nature."
Klas Strandberg
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