Cabinet bracing

[Dick Rees]

I've been working at maximizing the effectiveness of the gear that I have and in that line have been considering "modernizing" my speaker system. I'm running EV T-251+ tops.

ELECTRO-VOICE T251 SPECIFICATION SHEET Pdf Download.

In comparing them with the QRX series I've come across opinions that the "quality" of the sound of the QRX is a step up (even though the output or rated SPL is essentially the same) possibly due in part to a more robust cabinet. Speculation being that the lighter box may have some less than desirable resonance(s).

So if I want to stiffen things up with bracing, what do I look to do and what do I look to avoid?

TIA for any help.

DR

 

[Mike Smith]

Re: Cabinet bracing

Dick, I've never been inside one of those EV T-Series boxes, but in general: the most important single brace you can add to a speaker cabinet, if it does not have one already, is a front-to-back panel connection located in the space between the LF and HF components (or LF drivers if there are two). The difference is often not subtle. That's a very excitable part of a speaker baffle, and somewhat sketchy as far as material mass goes.

After that, any kind of stringers or dampers you can install on the back and sides will help minimize panel resonances, but the differences will probably not be dramatic on small to medium sized enclosures. Trap boxes and floor monitors are usually a bit tighter than square designs, thanks to the "triangulation" of the panels. Have fun and saw safely.

 

[Ivan Beaver]

Re: Cabinet bracing

I've been working at maximizing the effectiveness of the gear that I have and in that line have been considering "modernizing" my speaker system. I'm running EV T-251+ tops.

ELECTRO-VOICE T251 SPECIFICATION SHEET Pdf Download.

In comparing them with the QRX series I've come across opinions that the "quality" of the sound of the QRX is a step up (even though the output or rated SPL is essentially the same) possibly due in part to a more robust cabinet. Speculation being that the lighter box may have some less than desirable resonance(s).

So if I want to stiffen things up with bracing, what do I look to do and what do I look to avoid?

TIA for any help.

DR

Like Mike-i don't know what the insides are like. So we will "assume" no bracing. Front to back and side to side are good starts. Tie those 2 brace together in the middle-if possible.

Maybe some vertical braces on the sides and a horizontal brace between the woofer and the horn.

If possible use 13 ply birch. If not that use a hard wood. Don't use cheap plywood or MDF or chip board or particle board. Don't lay the braces parallel to the existing panels. Mount them 90° and 1.5-2" wide and 3/4" thick. Be sure to use a good wood blue and good fasteners. If possible tie these wall braces to the side to side braces.

Remember that any bracing will reduce the internal volume of air-so the tuning will move up. So don't go nuts with it. A couple of well placed braces "may" make a difference-but there is a point at which you are just wasting time-material and increasing weight.

 

[Craig Hauber]

Re: Cabinet bracing

You're a generation ahead of me, I'm still using some S & SH series boxes. Yes they were a bit heavier built I found but adding bracing to stiffen panels and some tension members between panels helped considerably.
I think they built the boxes out of a higher-grade OSB flake-board type panel they called "Road Wood" or something like that. (Is isn't quite like the crap you can get at Lowe's Depot so maybe it was custom-spec)
Re-enforcing around driver circles, handle and input holes helped too. Damping down the horn lenses as well as the plastic handle cups really helped also. (used an auto-sound stick-on sheet product for this)
Upgrading the "crossovers" (bi/tri-amping with DSP) made the most difference though. However ordering a new passive unit from a current model of similar type (12" & 1") worked quite well for those throw-and-go smaller shows