Reducing internal volume of a PE enclosure for N3S

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wgallupe

Hi,

I'm looking for ideas on how to reduce the volume of this PE box: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=302-740

If I figured correctly, Danny's N3S enclosure plans have an internal volume of 0.59 cu. ft. and the PE enclosure is 0.75 so I need to reduce by 0.16 cu. ft. I was thinking of laying the enclosure on its back and applying something like expandable foam insulation to a depth that would result in the 0.16 cu. ft.

Couple questions: Is this a rediculous idea? Would expandable foam be "solid" enough or is it too porous? What about an epoxy resin?

Thanks in advance.

   

S Clark

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Re: Reducing internal volume of a PE enclosure for N3S
« Reply #1 on: 10 Aug 2010, 12:54 am »
Expandable foam would work, but it would be tricky to get the volume correct.  You can cut styrofoam blocks to the exact # of cubic inches that you need to reduce the volume a lot easier.  Then just glue them in.  Any closed cell material (if you can blow through it, it's open cell) should reduce the volume.

Danny Richie

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Re: Reducing internal volume of a PE enclosure for N3S
« Reply #2 on: 10 Aug 2010, 01:55 am »
I just wish that they didn't put that brace in there turned the wrong direction. It creates an early reflection internally.

You'll have to follow these plans: http://www.audiocircle.com/index.php?topic=54352.0

Then take up some of the extra space by gluing in some braces going the other way. The stiffer the box ix the better it will sound.

wgallupe

Re: Reducing internal volume of a PE enclosure for N3S
« Reply #3 on: 10 Aug 2010, 12:39 pm »
Styrofoam! Of course. I knew someone would have a better idea... Thanks S Clarck.

Danny, Yes I am planning to do that mod to the brace. In fact, I actually did it to a pair of the .5 boxes but decided to go N3S instead of N2X. After I bought the .5 boxes I decided I wanted the N3S for: Higher sensitivity, more dynamics, and last but not least, the ability to convert to N3 transmission line when I can afford those cabinets.

Thanks for the help guys.

PS: Anybody looking for curved, gloss black PE boxes for N2X?  SOLD!!!

 
« Last Edit: 11 Aug 2010, 01:52 am by wgallupe »

Danny Richie

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Re: Reducing internal volume of a PE enclosure for N3S
« Reply #4 on: 10 Aug 2010, 02:01 pm »
You don't have to take that volume all the way down either. A little larger volume will be fine so long as you are not pushing the speaker too hard.

And I'd still recommend added layers of MDF as a best option.

Quote
PS: Anybody looking for curved, gloss black PE boxes for N2X?
 

If the price is really right then I might take them as trade ins toward some kits. I really need to get another demo pair out there.

BYOB

Re: Reducing internal volume of a PE enclosure for N3S
« Reply #5 on: 10 Aug 2010, 05:15 pm »
I have done similar with N3S and they sound wonderful. Danny recommended adding vinyl floor tiles, that was easy and covered the rounded surface.

I also added some extra MDF and the box seems very solid

wgallupe

Re: Reducing internal volume of a PE enclosure for N3S
« Reply #6 on: 10 Aug 2010, 09:45 pm »
I have done similar with N3S and they sound wonderful. Danny recommended adding vinyl floor tiles, that was easy and covered the rounded surface.

Those look great. Nice job. Thanks for the tip.

Wayne

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Re: Reducing internal volume of a PE enclosure for N3S
« Reply #7 on: 10 Aug 2010, 10:58 pm »
PS: Anybody looking for curved, gloss black PE boxes for N2X?
PM sent.