wrote:
I'm hoping smart people like Mr. Dorsey will chime in on this one:

I saw this design for an iso booth (it's like a pentagon):
http://www.vocalbooth.com/products/diamondseries.html

I thought this would be a great idea since there are no parallel walls.
But it is roughly approaching a "round" floorplan. And I learned from
people that a concave "round shape" is terrible for a room.

The reason a round shape is terrible is that it concentrates all the
reflections right in the center. An octagonal shape is almost as bad
because it has a bunch of parallel walls. The pentagonal shape is much
better because you never have two surfaces directly opposing one another,
so you don't get direct reflections between them.

In the case of the isolation booth, though, your whole goal is to make it
totally dead at higher frequencies, so the reflection problems aren't
severe except at lower frequencies where they turn into standing wave
problems. And I don't think the pentagon will really help to deal with
the standing wave issues much anyway.

So would you give this shape a thumbs-up or thumbs-down?
(I'm building an iso-booth this week).

I would give it a thumbs-down, because I am not sure it is really any
better than a simple rectangle, and it is a _lot_ harder to build than
a simple rectangle. Mitering all those wacky angles will take some time.
It might be a little bit better but it's a lot of work for a little bit.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."