SOFFITS and AIRGAPS!!!

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SOFFITS and AIRGAPS!!!

Postby Paul Woodlock » Thu Jul 22, 2004 12:27 am

Greetings Folks

I'm currently doing some more Studio Front Wall designs, and have a SOffit mount question.

When mounting Speakers in Soffits how important is the air gap distance between the Soffit and the Speaker cabinet?

The reason I ask is becuase at some point in the future I'd like to change the speakers I use for the next model up. And they're bigger.

So unless it's a bad idea acoustically, I'd like to make the soffits big enough to take the larger speakers, and in the meantime stuff rockwool in the gap that's left by using the current smaller speakers.

we're talking a difference of about 60mm ( 2.5" ) .

One part of me thinks that a larger soffit airgap would help with the decoupling of the speaker to the room structure, but another part of me thinks that speakers should be fitted tight into soffits.

And if this makes a difference to the answer, I will be placing the Speakers on concrete blocks, sitting on Sylomor blocks ( All within the soffit ). The weight of the speaker PLUS a big lump of concrete should give me enough load to be able to use my spare Sylomer P.

Anyone? :)

Much thanks!

Paul
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Postby knightfly » Thu Jul 22, 2004 7:48 am

Barefoot, our speaker mod over on John's site, has addressed this in the past - as I recall, it's no biggie to make the boxes bigger as long as you build a "filler" bezel that keeps the gap between the extended baffle (the soffit, or flush mount) and the speaker box to around 1/4" or less, and stuff insulation in the crack between speaker box and the temporary bezel. The end result should be a completely continuous plane that extends the front surface of the speaker box in all directions by 3-4 woofer diameters or more, with the woofer NOT quite centered in that plane. The idea there is that no two dimensions radiating outward from the woofer has the same distance, so any anomalies such as diffraction at edges, etc, don't have the exact same characteristics which would cause them to (possible) add.

That's 'bout all the "snake oil" I absorbed, you might wanna do a search here -

http://www.johnlsayers.com/phpBB2/viewf ... 10f8ba8f60

There are a few topics on the first page that should be of interest... Steve
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Postby Paul Woodlock » Thu Jul 22, 2004 12:52 pm

Cheers for that Steve! :)

I was indeed going to provide a close fitting front bezel.

It's looking good if I can simply replace the bexel when upgrding the studio monitors :) :) :)


I'll have a look through the John Sayers forum as you suggest. :)

Paul
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Postby Andrew Steel » Thu Jul 22, 2004 10:28 pm

Hi Paul,
I may be missing something big here, but why solid soffits? No matter what the size and speaker position, they must alter the step caused by the front panel - which the manufacturer would have accounted for in the original design (hopefully). I plan to use a shelf from behind for the speaker and then a light wooden farme full of fibreglass board, covered in fabric as the actual soffit - much less diffraction guaranteed! :-) It can also put a layer of absorbant metarial a good distance from the rear wall with associated benefits. What do you think? Is there an obvious reason for not doing this?

Andrew
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Postby Paul Woodlock » Fri Jul 23, 2004 1:10 am

Andrew Steel wrote:Hi Paul,
I may be missing something big here, but why solid soffits? No matter what the size and speaker position, they must alter the step caused by the front panel - which the manufacturer would have accounted for in the original design (hopefully). I plan to use a shelf from behind for the speaker and then a light wooden farme full of fibreglass board, covered in fabric as the actual soffit - much less diffraction guaranteed! :-) It can also put a layer of absorbant metarial a good distance from the rear wall with associated benefits. What do you think? Is there an obvious reason for not doing this?

Andrew


Greetings Andrew :)

Check out the Genelec Article on Soffits. http://www.genelec.com/support/soffit.php

btw - I use Genelc 1037B's which are designed to be soffit mounted. front port, removable amplifiers, etc.

hth :)


Paul
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Postby Paul Woodlock » Fri Jul 23, 2004 6:02 pm

Greetings Steve ( if you're about )

I haven't been able to get on the john Sayers forum over the lat couple of days. Is it down for maintenance?


Paul
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Postby Andrew Steel » Fri Jul 23, 2004 9:48 pm

Hi Paul,
Thanks for the link mate, makes a lot of sense. Do the Genelecs you are using have a shelving control as described?

Andrew
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Postby Andrew Steel » Fri Jul 23, 2004 9:56 pm

Hi Paul,
Thanks for the link mate, makes a lot of sense. Do the Genelecs you are using have a shelving control as described?

Andrew
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Postby Bob » Fri Jul 23, 2004 10:06 pm

Paul wrote
I haven't been able to get on the john Sayers forum over the lat couple of days. Is it down for maintenance?


I use this link
http://www.johnlsayers.com/phpBB2/viewforum.php?f=2
and it's been fine the past few days.
Regards
Bob Golds
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"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby knightfly » Fri Jul 23, 2004 11:11 pm

That link gets you direct to the Construction forum; main forum link is

http://www.johnlsayers.com/phpBB2/index.php

Good luck... Steve
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