Purpose of center brace in 412 cab

  • Thread starter Thread starter MadAsAHatter
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MadAsAHatter

MadAsAHatter

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Couldn't find a good answer with a search...
What is the purpose of the brace that's in the middle of 412 cabinets. Is it just for structural support in the middle of the baffle and back? Or would it have a tonal purpose like making the back resonate with the front?
Asking because I just started building a 212/115 cab and there's no space for the center brace the way the speakers will be positioned. I've also seen 412's with and without a brace.
 
If the back is flopping around too much it can sound like shit. If you build your back in a way that resonance is controlled without the post. That would probably sound the best. Maybe a piece of aluminum angle across the inside of the back. You could use it for a flushmount jack plate too.
 
PatF said:
If the back is flopping around too much it can sound like shit. If you build your back in a way that resonance is controlled without the post. That would probably sound the best. Maybe a piece of aluminum angle across the inside of the back. You could use it for a flushmount jack plate too.
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Yep....it can get 'woofy' for lack of a better term. Marshall started to screw in the center brace later..if you don't want to screw it in, you can make it tight (if it worries you) by putting in a folded piece of something (cloth, nylon, whatever) at the end of the brace when you screw the back on tight.
 
“
IF you build a 4x12 without that "brace," two things will happen. One, you'll find yourself with a nasty resonance in the audible range at a frequency associated with a multiple of the diagonal (in inches) of the big back panel. Probably the same thing with a 2x12.

In addition, a single panel of non-braced wood will "oilcan." When the speaker cones move back, the air pressure inside the cabinet increases and the panel of wood wants to bulge outward. When they move forward, the air pressure sucks that panel into the cabinet. This ultimately robs the speakers of power and increases the chances of a really unpleasant buzz.

The brace is an attempt to reduce both problems. A better solution is to put better bracing on the back panel (and the front, for that matter) to make both stiffer and reduce the distance over which a resonance can build up.”
 
I always screwed that center support to the back panel. My OS Mesa cabs were a mess before I did that. Woofy low end on palm mutes.
I’m always surprised that more manufacturers don’t do that stock.
 
I also screw the center post to the back panel on most of my cabs. Part of my checkup process on any used cab I buy. Pull back panel, check ohm reading with meter, check that all speakers are working, tighten all internal screws, seal back up and screw center post into back panel if not done already.

In my experience, this typically tightens up low end response and removes any buzzing if the post isn't butting up to the bck panel tight enough. Like others have said, some sort of soft material in between the post and back panel can fill up any gaps as well. I typically use foam
 
So it's mostly to add some rigidity to the back panel & and baffle to help tighten up bass response?
 
thegame said:
I drilled my Bogner 4x12's back panel to accommodate adding a screw to the center brace. As others said, tighter, less woof, more focused with it. Best 10 cent improvement ever.
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Really?!
Why didn’t you tell me that??
 
SQUAREHEAD said:
Really?!
Why didn’t you tell me that??
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Because I showed it to you when you were here. Maybe this will jog your memory. The previous owner of my other Bogner cab already did that little mod and I always wondered why that cab was tighter. Once I did the same to the other one, the two cabs pretty much evened out. I clearly remember crouching behind the cabs while pointing it out. No worries though, as I sometimes forget what I did 5 minutes ago lol
 
Ya, I think I remember now?
Now I gotta do it to my Bogner cabs!
 
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