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For the Acousticians - Geodesic Domes
Old 15th January 2005
  #1
Gear Maniac
 
Heterodox's Avatar
 

For the Acousticians - Geodesic Domes

You rarely hear of any studios built in a geodesic dome framework. Reasons?

They are incredibly cheap, and consistently feature ceilings boasting 30 feet at the peak. With the spacious, circular yet angular design, it would seem to be very easy to control problem frequencies.

Is this not so? Am I missing something?
Old 15th January 2005
  #2
Gear Guru
 
Ethan Winer's Avatar
 

Re: For the Acousticians - Geodesic Domes

Dox,

> You rarely hear of any studios built in a geodesic dome framework. Reasons? <

It's very simple: Curved surfaces focus the sound, which is the opposite of what you want (diffusion).

--Ethan
Old 15th January 2005
  #3
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enharmonic's Avatar
 

Re: Re: For the Acousticians - Geodesic Domes

Quote:
Originally posted by Ethan Winer
Dox,

> You rarely hear of any studios built in a geodesic dome framework. Reasons? <

It's very simple: Curved surfaces focus the sound, which is the opposite of what you want (diffusion).

--Ethan
Quite an interesting environmental challenge for Real Traps though...
Old 15th January 2005
  #4
chikkenguy
Guest
You could install hanging diffusion or something though...
Old 15th January 2005
  #5


Aren't these things basically a sphere? Like, with a specific radius...

Imagine the peak you would get at the center of the dome at THE fundamental frequency of the room. Wow!

I think there was a link posted in a thread about some guys in Germany using a large spherical tank (fuel tank, I think) for a reverb chamber, or maybe they were recording inside of it. Either way, it sounded eerie....



-tINY

Old 15th January 2005
  #6
Motown legend
 
Bob Olhsson's Avatar
 

Making a dome that would be massive enough to be soundproof would be difficult and very expensive, probably considerably more so than conventional construction.
Old 16th January 2005
  #7
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Heterodox's Avatar
 

The domes aren't perfectly circular though. They are angular, made of trianges...the completed structure just forms a 360 degree rotation. Sounds would deflect to many directions.

Also, the entire studio wouldn't be housed in the dome without any dividing structure. I'm more thinking along the lines of building a multi-roomed studio within the confines of the dome. Thus, certain walls of rooms would be flat, while others would be angular. Adding simple diffusors and traps along carefully selected areas seems like it could work really well.

tINY, the dome you speek of is actually a full sphere, perfectly circular, and made of steel. Of course that is a reverb chamber from hell (but the songs were really neat, if you happened to check them out).

Take a look at some of these rooms...can't you imagine them sounding very nice with a few well placed acoustic embellishments, and possibly an added wall or two (maybe even gobos?).









Or how about a whole studio complex made of connected domes?...





I guess my only real point is that they aren't REALLY circular, thus shouldn't have the typical acoustic nightmares of rounded rooms. Am I completely off base on this?

Additional ideas, critiques?
Old 16th January 2005
  #8
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Riad's Avatar
 

You know Biosphere 2 is for sale... that might work.
Old 16th January 2005
  #9
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if I recall - Vince Clarke has his studio in some type of dome... I'll look for a reference.

"-)
Old 16th January 2005
  #10
Gear Nut
 
mesmer's Avatar
 

I live in a geodesic dome. It was built in 1967 by Pao who created the Smurfs. Everything is electric blue. there are Smurf sized doors that go to storage rooms. The acoustics are madening. If you walk in the front door and some one whispers upstairs, It sounds like they are in your head. If you're six feet from the kitchen and want to speek to some one cooking, You have to yell.
Peter
Old 16th January 2005
  #11
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Heterodox's Avatar
 

Good and well, but I'm sure the basic acoustic designs have matured a bit since 1967 - architecturally and material wise. No?
Old 16th January 2005
  #12
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The only advantage for a dome that I can think of is the high ceiling in the center. A completely open dome will focus the sound parabolically into the MOARN (Mother of all room nodes) and leave much of the space unusable with null points, but a well designed room in the middle of the dome could be a great room, in my largely inexperienced opinion.
Old 16th January 2005
  #13
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I record routinely in a couple of churches that are made from Geodesic domes. I wouldn't wish that acoustic on anybody...

--Ben
Old 16th January 2005
  #14
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Heterodox's Avatar
 

Honestly, that bad Ben?

Could someone show some actual physics or something here? I realize CURVED surfaces focus sounds, but wouldn't the angled panels cause sound to be reflected in a variety of directions?

As per your thought 2leod, the idea would really be rooms within the dome. The center would not be the only advantage either...I mean its 30-40 feet at zenith, making it easily 10-20 along the edges.

I think everyone is missing the basic point of the dome being the framework for a multi-roomed interior. In other words, nobody is going to put their console on one side of an untreated hemisphere and tell the band to go stand in the middle and play. This would be just as horrible as a big open rectangle. But if the high ceiling and angled framework were utilized properly...
Old 16th January 2005
  #15
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mesmer's Avatar
 

Think about it, it's a prism. Don't wast any more time on this one. It is the third worst acoustical enviroment I have ever heard.
seriously
Peter
Old 16th January 2005
  #16
Quote:
Originally posted by Heterodox
Could someone show some actual physics or something here? I realize CURVED surfaces focus sounds, but wouldn't the angled panels cause sound to be reflected in a variety of directions?
I'm pretty sure that it appears as a curved surface until the panels are larger than 1/4 wavelength (perhaps it's half in this case, I don't recall) of the low frequencies you wish to support...
Old 16th January 2005
  #17
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I saw Santana and the Dead in the Tacoma Dome, a huge wooden geodesic dome venue.

The echoes were completely out of hand- it was tres bizarre.

Made for a very interesting "space" segment though! After which, it seemed the Dead had probed and plumbed the acoustics and the audience was able to make sense of what was happening on stage.

As for using a dome as a shell for completely differently shaped rooms, why not, and why bother?

I will note that the places where I see people building geodesic domes are usually quite remote, and sonic isolation might not be the approach so much as "let it bleed" on out through the walls.
Old 16th January 2005
  #18
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Oh it would definitely be a "let it bleed" situation.

Brad, could you possibly expand on that? Ethan, any more knowledge to be had?

I'm getting the general idea that I'm wrong here, but I'd certainly like to educate myself further as to why.

I understand the focusing effects, but don't those only apply if there is an opposite wall with the same angle? And further, if the triangular panels on the "curved" side of the room had simple diffusion...something like the random, stilted wood panel designs (more or less duplicating the effects of a bookshelf)...wouldn't that go ahead and eliminate the negative, focusing aspects?
Old 16th January 2005
  #19
chikkenguy
Guest
even though it is constructed of triangles, if you are in the center of the room, each of those triangles is aimed right back at you. every surface in the room besides for the floor will reflect your signal right back at you and create the biggest room node ever(exaggeration, but partially true).
Old 17th January 2005
  #20
Gear Guru
 
Drumsound's Avatar
Quote:
Originally posted by mesmer
I live in a geodesic dome. It was built in 1967 by Pao who created the Smurfs. Everything is electric blue. there are Smurf sized doors that go to storage rooms. The acoustics are madening. If you walk in the front door and some one whispers upstairs, It sounds like they are in your head. If you're six feet from the kitchen and want to speek to some one cooking, You have to yell.
Peter
Peter,

Do you find it to be a hard place to live? Even if it weren't Smurf blue your description sounds like it would drive the inhabitants mad!
Old 17th January 2005
  #21
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OK, so if it is designed to leak bass up to frequency x, and a lot of the triangles have quadratic diffusors built on to them, that are good down to frequency x, that should work, no?
Old 17th January 2005
  #22
chikkenguy
Guest
youd have to have some big ****ing diffusors to be effective at bass freqs though...
Old 17th January 2005
  #23
JTR
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Gents

Geodesic or circular rooms don't work because of compounded acoustic angles;
no amount of diffusion/absorption/quadratic treatments will address this fundamental issue; by the time you've "fixed" the problems, you have spent inordinate amounts of cash, and shrunk interior capacity by a large percentage

No offense Heterodux, but you seem to have asked a question seeking education, and then proceeded to argue with informed respondants...

It does not work

Except the Capitol Records Tower in Hollywood, which is circular, but that's only so the CEO can tell all the obnoxious V-P's to go piss in a corner, and keep 'em confused for the rest of the day
Old 17th January 2005
  #24
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What I'm thinking is, if the dome is lightly constructed in a way that is typical of domes, so most of the bass leaks right out, the diffusor would only have to diffuse higher frequencies.

I haven't done the math though- I don't know how high a frequency of bass would leak on out, and how deep the quadratic diffusor would need to be to function down to that "leaky bass" frequency.
Old 17th January 2005
  #25
JTR
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I think that you would be dealing with 2 issues


1

if the dome is of a large enough dimension to make fundamental modes a non-issue, the reverb time would be a significant problem... as one of the previous posts mentioned with respect to a sports/event dome in the pacific northwest

2

If the dome is small enough to restrict excessive reverb times, it will be creating/supporting modes whose frequencies are within the active range for musical energy, with all the attendant problems.

Having experienced both small ('hippy commune" style) and large ( American pavilion at the 1967 Montreal World's Fair) I can confirm that they all have a "sound" which is not really conducive to controlled recordings

But they look dope. God Bless Bucky!
Old 17th January 2005
  #26
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Quote:
Originally posted by JTR
God Bless Bucky!
Not to derail the topic at hand, but if anyone is interested there are carbon structures named after his design called Bucky Balls and Buckytubes that display near magical properties of strength, electrical and thermal conductivity. Pretty cool stuff to the geek in me...

BTW, I was just a wee tyke when I went to Expo '67, but I do remember the weird acoustics in that American Pavilion.
Old 17th January 2005
  #27
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pedalboy's Avatar
 

I ran sound for a band at a church that was inside a geodesic dome once... It was a complete disaster.

because of the strange acoustics, you would hear one mix in one seat and a vastly different one just feet away! The only thing i could do was to clear the vocals and try to look like I knew what I was doing.

So needless to say I think you'll have some "issues" to deal with if you try it.
Old 17th January 2005
  #28
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Quote:
Originally posted by Heterodox
Honestly, that bad Ben?
Yeah, that bad...

You end up with the weirdest reflections and places in the room where it almost feels like the world is out of phase. I'd rather record in a room with a parabola behind a stage because at least with that, I can figure out where the bad spots will be...

You can work around the bad acoustics, but why would you choose to subject yourself to this?

--Ben
Old 17th January 2005
  #29
Moderator
 
Tim Farrant's Avatar
 

I would suggest that if you like the shape of the geodesic, then build a rectangular outer sound containing shell and build the interior with absorbent material into the dome shape. Some surfaces could be hard, some soft, but all light weight. Best of both worlds and damn obvious if you ask me!

Oh, I forgot to add that a sphere or half sphere is based on a cubic geometry, which as we know is the worst possible acoustic shape.

Tim
Old 17th January 2005
  #30
Gear Maniac
 
Heterodox's Avatar
 

Quote:
Originally posted by JTR
No offense Heterodux, but you seem to have asked a question seeking education, and then proceeded to argue with informed respondants...
I'm not arguing, I'm asking for a more detailed explanation of "why not." And I'm getting some pretty excellent replies, yours included.

And in continuing that...

If you were to build walls across from the dome walls, within a close enough proximity, wouldn't that cancel the nodes? Something like....


/--------- <-
/ |
Dome -> | | <- Interally constructed walls
Frame \ |
\--------- <-


Arrrggg...I just wish I could see a computer generated animation of exactly what would happen if you hit a snare in the above described room. I see the dome frame reflecting it back, but it would hit the opposite wall before reaching a point of full focus and creating massive nodes....no?
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