Cabinet Construction

[TeeWX]

( I am not really sure where this should go as there doesn't seem to be specific place for DIY threads )

I have a few questions about cabinet construction for those who are well versed in this area. I have done significant searching on these topics but have not really found anything specific enough to answer them.

Most speaker cabs that I've seen seem to just be bare 3/4" plywood construction, sometimes using small amounts of 1x2 or 1x1 etc bracing just on some interior edges. However, greenboy cabinets seem to be 1/2" plywood construction with bracing going through the centers of the main walls. I'm not exactly an expert on the physics interactions between sound waves and wood, but it seems to me that you would be better off using lighter 1/2" plywood and achieving most of your rigidity through bracing. Is there a clear design choice winner here?

Another question I have is that some speaker cabinets have their insides lined with carpet or egg crate foam and similar products. How much of an effect does this have on the cabinet?

Lastly, is there something about guitar cabinets that makes them disregard similar design choices made by bass cabinet builders? (I understand porting, I am NOT asking about that) It just seems that many guitar cabinet companies will put pretty much any speaker or combination of speakers in the exact same cabinet. My general thinking is that a cabinet should be designed to get the most out of the specific driver being used. What is the reasoning for this?

Thanks!

 

[B-string]

3/4" with glue blocks are old construction. 1/2" with bracing is lighter and provides better control of resonances (a very good thing).

Treatment of the interior controls standing waves and internal reflections. It can be underdone or overdone, some may choose none as a voicing choice.

Guitar cabs are not critical designs as they generally are not required to reproduce low frequencies.

 

[T_Bone_TL]

Foam and fiberglass is another choice. Messy and not woodworking, but can end up lighter and so stiff it doesn't need bracing - also friendly to (but rarely seen as) a non-rectiliniar cab (which can increase stiffness even more.)

A link to BogeyBass' "modern-style" braced construction with lots of pictures and a cautionary tale....

Guitar cabs can do "whatever" because they are primarily operating in the part of the plot (WinISD or whatever you care to use) that doesn't change much/at all when you change the box, or driver. That would seem to add more fuel to the "fundamental , schmundamental" argument, since Guitar low E is 82 hz, which is solidly in the "typically affected range" but may also have to to with guitarists caring more about the high end than the low end. Or fundamentally not wanting "flat" cabs, fussing around with "physical EQ" by choosing a cab for the sound (whacky response curve) it has rather than using a flat cab and eq-ing to get the sound they want. Most-but-not-all bass seems to have moved towards the flat(tish) cab and amp with EQ, guitar less so.

Aside from damping reflections, stuffing/batting/foam is supposed to increase apparent volume of the box (by slowing down the sound - if it goes slower, the box "looks" bigger acoustically.) It's fairly common, can be a quick retrofit, and can be altered easily if you want to try variations. Ranges from none to stuffed nearly full.

 

[fefypatan]

tiragoma gacetero una buena caja

 

[Mr. Foxen]

If your design aim is fast cheap construction, thicker wood and no bracing wins. If it is a lightweight quality cabinet, then bracing and thin wins.