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.

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

GP,

it is roughly approaching a "round" floorplan. And I learned from people
that a concave "round shape" is terrible for a room.

Round and similar shapes are a problem, but that problem goes away if all
the surfaces are covered with absorbing material. A small booth needs to be
covered mostly or completely anyway, so with enough absorption on the walls
that shape will be okay.

--Ethan

"Ethan Winer" ethanw at ethanwiner dot com wrote in message
...
GP,

it is roughly approaching a "round" floorplan. And I learned from
people
that a concave "round shape" is terrible for a room.

Round and similar shapes are a problem, but that problem goes away if all
the surfaces are covered with absorbing material. A small booth needs to
be
covered mostly or completely anyway, so with enough absorption on the
walls
that shape will be okay.


How big could you build a shape like this, assuming that the walls are
covered in Auralex or the eqivelant, before you would start to have a
problem?

jb

In article ,
reddred wrote:

"Ethan Winer" ethanw at ethanwiner dot com wrote in message
...
GP,

it is roughly approaching a "round" floorplan. And I learned from
people
that a concave "round shape" is terrible for a room.

Round and similar shapes are a problem, but that problem goes away if all
the surfaces are covered with absorbing material. A small booth needs to
be
covered mostly or completely anyway, so with enough absorption on the
walls
that shape will be okay.

How big could you build a shape like this, assuming that the walls are
covered in Auralex or the eqivelant, before you would start to have a
problem?

Auralex will kill the high end issues, so your first problem is going to be
low end resonances.

If we figure that the foam becomes pretty useless around 500 Hz, then a
round room that is a wave across at 500 Hz is going to start being a problem,
right?

And that would be... what, about 32 inches?

Hmm... anyone care to try a better back-of-the-envelope calculation?
This doesn't sound quite right to me, overall.
--scott
(who thinks there is a special place in hell for architects who
design octagonal churches)
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

thanks for the insights, Mr. Dorsey.

the two most important functions of the iso booth will be to record
vocals and to record a cranked 4x12 guitar cabinet.

would getting some of these RPG "modex corners" actually help?

http://www.rpginc.com/products/modexcorner/index.htm

i could almost see myself raising up the guitar cabinet and then
"surrounding" the perimeter of the guitar cab with these modex things.

wrote:
thanks for the insights, Mr. Dorsey.

the two most important functions of the iso booth will be to record
vocals and to record a cranked 4x12 guitar cabinet.

would getting some of these RPG "modex corners" actually help?

http://www.rpginc.com/products/modexcorner/index.htm

i could almost see myself raising up the guitar cabinet and then
"surrounding" the perimeter of the guitar cab with these modex things.

I don't know. I'd bet that if there _were_ big standing wave problems in
the room, you could compensate for them with placement, in the case of
the guitar amp. You can move the amp and the mike around to deal with
all kinds of problems.

I can't see the RPG gadgets really doing much at the low frequencies where
the problems are really going to be. But I might be wrong....
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

GP,

the two most important functions of the iso booth will be to record vocals
and to record a cranked 4x12 guitar cabinet.

For a cranked guitar cabinet you need substantial absorption at low
frequencies. Thin materials won't do that.

would getting some of these RPG "modex corners" actually help?

RPG Modex bass traps are great, if expensive, but they're not appropriate
for this application. Modex traps are available tuned to different frequency
ranges, and those ranges are better suited for larger rooms. What you need
is broadband absorption that works well down to the lowest frequencies, not
just over a narrow range.

i could almost see myself raising up the guitar cabinet and then
"surrounding" the perimeter of the guitar cab with these modex things.

Modex traps are meant to be stacked in corners, not placed out in the room.
If you get EQ magazine, the current (January) issue has a review of my
company's MiniTraps. The reviewer specifically mentioned how successful
MiniTraps are for exactly what you describe.

--Ethan

JB,

How big could you build a shape like this, assuming that the walls are
covered in Auralex or the eqivelant, before you would start to have a
problem?

It's not at what *size* you need more than thin foam on the walls, it's what
*frequencies* will be sounding in the room. If it's for voice only, the
requirements for a booth are not as stringent as when recording a guitar or
bass amp or string bass player or drum set.

--Ethan

How big could you build a shape like this, assuming that the walls are
covered in Auralex or the eqivelant, before you would start to have a
problem? BRBR


Small rooms tend to have more problems and are harder to treat than large
rooms. A larger room, if nothing else, affords you the space necessary to
build proper bass traps. Auralex and the like won't do anything to tame low
frequencies, so a round room whether covered with Auralex or not will have gobs
(the technical term) of low frequency energy reflected toward its center
center. A spectacular example of this is the globe room at the Christian
Science Monitor building in Boston. It's a globe-shaped room with a bridge
spanning the horizontal axis. At the center you can hear everything anyone in
the room is saying. It's really cool, but I wouldn't want to record or mix in
it.


Joe Egan
EMP
Colchester, VT
www.eganmedia.com

"EganMedia" wrote in message
...
How big could you build a shape like this, assuming that the walls are
covered in Auralex or the eqivelant, before you would start to have a
problem? BRBR


Small rooms tend to have more problems and are harder to treat than large
rooms. A larger room, if nothing else, affords you the space necessary to
build proper bass traps. Auralex and the like won't do anything to tame
low
frequencies, so a round room whether covered with Auralex or not will have
gobs
(the technical term)

Actually "gobs" in itself is not a technical term, it's only when you start
breaking it up into "milligobs" & "nanogobs" is when it warrants a tech
definition.

Neil Henderson

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."

The reason a round shape is terrible is that it concentrates all the
reflections right in the center.

What reflections? Acoustical treatments get rid of reflections.

Truth wrote:

The reason a round shape is terrible is that it concentrates all the
reflections right in the center.

What reflections? Acoustical treatments get rid of reflections.

Not in a tiny vocal booth, and nowhere else, either, except for anechoic
chambers.

--
ha

Scott, I'm killing you here with all these questions.

But since you thought the pentagon shape would only bring marginal
gains over the rectangle in this example...

do you think a rectangle that adheres to one of the "golden ratios" (1:
1.4: 1.9 for example) would be a better strategy than the pentagon?
you have me thinking about standing waves!

GP,

do you think a rectangle that adheres to one of the "golden ratios"
(1:1.4: 1.9 for example) would be a better strategy than the pentagon?

Yes. There are other good ratios too. If you download my Graphical Mode
Calculator (PC only) it lets you play with different dimensions to see their
affect. It also lists several "preferred" ratios. Here's the link:

http://www.realtraps.com/modecalc.htm

--Ethan

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.

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

With the right acoustical treatment, I have never had problems with any
room, no matter what the size or shape.

"Truth" wrote in message
...
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.

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

With the right acoustical treatment, I have never had problems with any
room, no matter what the size or shape.

I guess we'd have to know what kind of material you record to understand why
you make that assertion. IMO, for many recordings the room is an important
part of the sound. Further, where that applies, some rooms simply cannot be
'fixed'. Of course, they can be made to essentially disappear from the
recording, but that can be a bad thing. If you're recording mostly direct
or close-miked instruments you can get away with a lot. Before I had the
experience of working day-in and day-out in a really well proportioned
studio of sufficient size to provide a variety of acoustic areas, I had no
idea how much the room affected the results and how much easier it became to
do first rate work.

Steve King