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Multi-Way Conventional loudspeakers with crossovers

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Old 17th September 2003, 10:03 AM   #11
Vikash is offline Vikash  United Kingdom
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Quote:
You may want to check your internal ratios (WxHxD). Looks like you will have some nice standing waves with your present dimensions.
I've started a new thread on this.

Thanks for the input guys...

I will get some mdf and do it properly. How about this?:
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Old 17th September 2003, 04:53 PM   #12
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I'd move the horizontal braces to just behind the woofers -- with the woofer magnets jammed up tight against the brace.

The second "vertical brace would be better if it wasn't parallel to the 1st one.

dave
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Old 18th September 2003, 05:18 AM   #13
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well if you ding that (braces jamming woofers) then use a stronger bolting mechinism to bolth the woofer to the baffle than a simple wood screw.
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Old 18th September 2003, 05:29 AM   #14
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For what it's worth, I had a look inside a friend's B&W 640s a while back and that had one vertical brace from top to bottom and that was all. Cabinets are quite dead.

Or, you could try a translam

Mos
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Old 18th September 2003, 06:55 AM   #15
navin is offline navin  India
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the way i check my cabs is using a docs stethescope.
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Old 18th September 2003, 07:02 AM   #16
navin is offline navin  India
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oops i forogt....

bracing helps push res. freqs. into upper mid range. this is where most damping materials work best. using a combination of bracing and damping materils helps deaden a cabinet.

you may rap a cabinet wiht your knuckles and it may not "give" but if there is any resonance freq. it will excite. the idea is to eliminate these freqs.
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Old 20th September 2003, 07:47 PM   #17
Vikash is offline Vikash  United Kingdom
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I knocked the cabinet to see the effects (although it's only half built) and was suprised at how much the largest wall moves (reflected light). Quite an eye opener. I also loosely attached the opposite wall (no screws or glue yet) and knocked on that side - the result being a much lower frequency echo - It's nice to have it proved practically. I'll be knocking on my cabs a lot during the bracing stages... I guess I'm aiming for as higher (knocking) pitch as possible before the stuffing goes in.

I was looking at all the offcuts lying around, and there's a lot! (of long thin pieces) I'm wondering if I could just use these and place them in arbitary places both top-to-bottom and front-to-back. (In addition to the one proper vertical shelf brace)?
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Old 20th September 2003, 09:32 PM   #18
SimontY is offline SimontY  United Kingdom
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Hi,
Quote:
bracing helps push res. freqs. into upper mid range. this is where most damping materials work best
How about some lovely bitumen here? Line the larger spaces, maybe just on the outer walls.

You can get it from Maplins as 'Brown Bread' or from Wilmslow Audio (not tried theirs yet, but it's far cheaper than from Maplins). The stuff is just incredible for damping thin metal ie. cd player chassis etc., though I'm not sure of it's effectiveness on wood.

Just an idea, and it's something I intend to use more in my speakers soon. I've not really tested to find where they resonate most, but I suspect the midrange is affected, maybe making it a little more edgy than it could/should be...???


-Simon
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Old 20th September 2003, 10:39 PM   #19
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Quote:
Originally posted by SimontY
How about some lovely bitumen here? Line the larger spaces, maybe just on the outer walls.
This just lower the frequency the panel resonates at countering the lots of bracing.... also tends to store energy for later release.

dave
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Old 21st September 2003, 11:03 AM   #20
SimontY is offline SimontY  United Kingdom
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Quote:
This just lower the frequency the panel resonates at countering the lots of bracing.... also tends to store energy for later release.
Hmm, that sounds bad. But don't we want a lower frequency to resonate at? Like commercial speakers...resonance in the midrange sounds like a disaster. My idea of bracing is not to increase the resonant frequency, but to reduce resonances!

If one whacks in loads of bitumen/other heavy material won't we reduce resonance, as well as change its frequency? (or am I ignoring some law(s) of physics?)

Currently, mine seem to resonate somewhere between 200-500hz. I think it is a good sign I can't pinpoint it much closer


-Simon
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