I would not put it exactly in the middle of the box. Put it at 3/5 or 4/7. This makes the reconance of the part in front of the brace different from the part behind the brace.
I would be inclined not to brace top to bottom, as these are the most rigid panels. The baffle will be the weakest, especially between the woofers. I would suggest a similar MDF arrangement to yours but front-to-back, one between the woofers (with cutout around the tweeter) and another one lower down. A brace can also be run between the lower crossbrace and the upper port to support this.
Cheers
Cheers
Why not place it diagonally. I mean from bottom Left to Top right.
That would give you the best of both worlds.
Gaz
That would give you the best of both worlds.
Gaz
Just came across this thread:
I've read this before as well. Argh. Gonna have to do some reading now...
Ok, what about the holes in the brace? I was actually thinking about like 20 x 8cm dia. holes. How do I know when there's enough space for the cabinet to breathe through the brace without negative effects?
I've read this before as well. Argh. Gonna have to do some reading now...
Ok, what about the holes in the brace? I was actually thinking about like 20 x 8cm dia. holes. How do I know when there's enough space for the cabinet to breathe through the brace without negative effects?
I tend to agree with this rather than putting the brace parallel to the long panels, which tends to flex more than short panels.Centauri said:
You may want to check your internal ratios (WxHxD). Looks like you will have some nice standing waves with your present dimensions.
Centauri said:
i agree with this. front to back below woofer and behind tweeter should help most.
If there is only enuff material for a single brace then you have it right... do make sure that the brace divides the panel unevenly... a ratio with an irrational number is best.
The side panels are the largest and will resonate at lower frequencies than any other panel, so they are the most important to divide up.
If you can slant the brace so as to divide the side panels into non-rectangular shapes even better.
perhaps you can use some of the materials from the holes to brace the back of the woofs against the brace -- you could line up the "not hole" part of the brace to facilitate this -- if you can run the woofer braces all the way to the back (ie a 2nd bit from the brace to the back, even better.
Mounting the drivers push-push would be even better, then you can have active vibration cancellation.
dave
The side panels are the largest and will resonate at lower frequencies than any other panel, so they are the most important to divide up.
If you can slant the brace so as to divide the side panels into non-rectangular shapes even better.
perhaps you can use some of the materials from the holes to brace the back of the woofs against the brace -- you could line up the "not hole" part of the brace to facilitate this -- if you can run the woofer braces all the way to the back (ie a 2nd bit from the brace to the back, even better.
Mounting the drivers push-push would be even better, then you can have active vibration cancellation.
dave
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?:
Attachments
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
The second "vertical brace would be better if it wasn't parallel to the 1st one.
dave
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.
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
Or, you could try a translam
Mos
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.
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.
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)?
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)?
Hi,
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
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
SimontY said:
This just lower the frequency the panel resonates at countering the lots of bracing.... also tends to store energy for later release.
dave
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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