ok a bit confused. Pardon.
what if I put an aluminum bar across width wise and front baffle to back of the cab?
It is entirely likely that whatever you do, expectation bias will cause you to hear an 'improvement' due to your efforts. That having been said, sensibly bracing otherwise unsupported or unconnected faces of the enclosure is relatively unlikely to do much harm harm, but bear in mind that stiffening a panel will raise its resonant frequencies and these could be become audible in the critical midrange. The BBC published many research papers regarding panel audibility and although old they are still pertinent - well worth a read.
^^ Yes, that's usually a good thing. So is tying it to a side to side brace so that both front and back panels don't vibrate in the same direction at the same time where the brace does nothing.
Regarding the diagram, read the explanation at the bottom. It's not trying to tell you directly how to brace a cabinet.
Regarding the diagram, read the explanation at the bottom. It's not trying to tell you directly how to brace a cabinet.
Any 2 parallel sides. All of them if you can, but particularily the baffle to the back since the baffle is usually the weakest panel.
It doesn’t hurt to do more than one per axis if it seems it would help (bigger cabinet).
dave
yeah and why their monitors had no bracing.
good point.
how much bracing increases the resonant freq I don’t know Of course. No one really knows unless you measure.
since what I thought of as bracing is completely reversible it might be worth an experiment.
just two thin aluminum bars across the width in two places. So it would be more P2P bracing.
Something like a 18mm a 50mm wide or so, can be fitted edge on to any face to create an i-beam effect which can also be useful.
Retrofitting you ar elimited to what you can get into the box.
If you are starting from scratch the braces i prefer are essentially the above taken to extremes.
A “holey” brace (aka [proper] shelf brace) extends to reach 4 faces. This one also braces the driver to the back.
While you ar elimited when you are doing a retrofit, there are some general guidlines that still apply.
A brace should be placed such that the subpanels it creates has a higher aspect ratio than the original panel. These 2 subpanels should not be the same.
dave
For practical use a mechanics stethescope can VERY quickly tell you where resonaces are. And to some extent magnitude. I have both, the accelerometer is of academic interest but the sthescope is way more practical.
dave
Pull the foam out?
I don’t find foam very good for damping. You can play with that as well. Usually in a BR you do not want so much.
SEAS woofer. 5.25”? Tweeter too? Looks like it could be one of the nice 19mm units.
The vent is out the bottom? If it is these are ML-TLs and not a reflex and they require from lined to fully filled depending...
Crossover?
Given the high aspect ratio, simple crossbraces form side to side and the end-on strips down the length )not sure how long you sre going to be able to feed thru the driver hole.,
dave
I don’t find foam very good for damping. You can play with that as well. Usually in a BR you do not want so much.
SEAS woofer. 5.25”? Tweeter too? Looks like it could be one of the nice 19mm units.
The vent is out the bottom? If it is these are ML-TLs and not a reflex and they require from lined to fully filled depending...
Crossover?
Given the high aspect ratio, simple crossbraces form side to side and the end-on strips down the length )not sure how long you sre going to be able to feed thru the driver hole.,
dave
both are SEAS 6.5” woofers. Made for Proac.
i emailed SEAS for their specs but they haven’t got back to me. Doubt they would give me the specs anyways.
the tweeter is a scanspeak https://www.scan-speak.dk/datasheet/pdf/d2604-830000.pdf
port is down firing.
this is the crossover.
what’s a BR?
In this hobby of ours it is of utmost relevance to be able to measure driver specs yourself, so why not invest in a solid measurement combo? There has been discussed a lot on that topic. It will make you feel so much better not needing to depend on manufacturer's grace to provide some specs which aren't exactly a military secret.
edit: I suppose there is not all that much improvement potential with this speaker, and this is just my gut feeling.
edit: I suppose there is not all that much improvement potential with this speaker, and this is just my gut feeling.
That would depend on the mode shape of the loudest resonance and whether your bracing influenced it. If it did and made the resonant frequency higher that generally won't make the cabinet quieter. Even though the stiffening has made the speaker deflect less, at higher frequencies a smaller deflection is required to be equally as loud as a larger deflection at lower frequency. This is why tiny tweeters deflecting small amounts are able to be as loud as large woofers deflecting a lot.
Stiffening the baffle around the drivers is a positive thing to do because it will reduce the amount of energy transferred from the vibrating driver into the cabinet to then be dissipated via damping or radiated away as sound. However, running a rod from the middle of the baffle to the middle of the rear panel will likely make things worse. This is because it will introduce a new mode with substantial mass where the baffle moves in and out, the rod moves in and out and the rear panel moves in and out all in phase with each other. This new low frequency mode may well be louder than any of the modes in the "unbraced" cabinet.
If you want to stiffen a baffle with rods to make a cabinet quieter you will need to understand the mode shapes of the cabinet and what adding the rods will do to those mode shapes. If you don't have this knowledge and want to make changes to the cabinet that are unlikely to do more harm than good then add damping to the cabinet walls. It may be ineffective but shouldn't do much harm beyond pinching a bit of internal volume so don't over do it.
