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Old 25th October 2007, 02:52 AM   #11
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I haven't worked with Gorilla Glue but I know it takes clamping - for quite some time - before it bonds, so if you're working with a sealed cabinet that could be problematic and time consuming.

Titebond isn't very expensive for a small bottle - get III - you literally hold in in place for a matter of seconds and it sticks - it isn't permanent for awhile but the pieces won't separate.

The acoustic foam is available in self-stick form, but it doesn't hold very well if you place it over damping sheets - you'll want to use a little spray contact cement to help - out of a tube is OK too if you have that lying around.

Yes you can tack the polyfill - best with just a little spray glue in a few spots - and don't tamp it down - it can compress and lose some of its effectiveness. I've actually had pretty good luck without gluing polyfill - it is so light it pretty much stays in place by itself.

And don't worry about the simple questions - they're the easiest to answer!
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Old 25th October 2007, 03:34 AM   #12
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just noticed on my last post talking about the roofing shingles. it almost sounds as though I would be using them as bracing. my mistake on that. I was refering more to use it for a to help dampen the sound not brace.
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Old 25th October 2007, 05:54 AM   #13
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Quote:
1) Rib bracing - lengths of wood applied across the widths of the
interior panels.

2) Panels of mdf applied to the interior walls -- self-adhesive damping pads -- lead
For an after the fact bracing job ribs are effective & practical. Braces can br plywood, hardwood or metal. Stiffer is better but hardwood or ply are probably easiest. MDF should be avoided.

Easiest is to actually put the ribs on the outside of the box... but unless you get creative probably won't pass the aesthetics test. Inside you want to use the longest pieces you can get thru the driver hole. You want to place them so that one end is in a panel-panel join and they create subpanels that are long & skinny. If they are non rectangular all the better, Do not run braces at even intervals... the middle of the panel is the worst place to put it.

Lead is poison. Avoid it.

doing the things suggested in item 2 actually reduce the effectivemess of item 1.

I wouldn't worry all that much about how much volume you use up... damping like polyfluff or fiberglss insulation can make the apparent volume of the cabinet up to 20-30% larger. If the box is a base reflex interior volume damping will make the BR less effective (there are ways of dealing with that, personally i'm not a big fab of BR, and tend to end up stuffing the port with foam to make the box aperiodic.

In addition to the volume damping, I like lining the walls with wool felt or cotten felt. Acoustic foam aims to serve the same function but is not as effective. Fairly dense fiberglass works a bit better, but fiberglass is not something i like working with.

Quote:
Of course traditional shelf bracing is best
Just a note on this... as usually illustrated & implemented shelf bracing is not as effective as one might think... it usually divides panels sucj they are closer to squares... it would be much more effective if configured such that the aspect ratio of the subpanels becomes larger.

dave
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Old 25th October 2007, 06:29 AM   #14
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Originally posted by planet10
For an after the fact bracing job... blah, blah, blah...
All that said, Chris (my symbiot that won't let me build a box anymore) would say,... it is easier to start from scratch.

dave
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Old 25th October 2007, 07:58 AM   #15
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I have experimented wwith what I call an "Active Brace" on several models which have worked out quite well.

I have used a turnbuckle to pull opposite panels towards each other and a threaded rod to push them apart.

Either way takes up little volume and allows access to the crossovers since they are removable. Incedible amount of torque can be applied co care must be taken when tightening.


Removable "Active Brace"
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Old 25th October 2007, 08:09 AM   #16
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Originally posted by polkymon
I have used a turnbuckle to pull opposite panels towards each other and a threaded rod to push them apart.
Another very good technique...

dave
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