Speaker cab question

[ChampiBoy]

Hi everyone, this is my first post here. I read on this awesome forum since weeks and now have a question for you.

After reading about speaker cab construction, i saw that some use fiberglass inside them to prevent the wood to dampen the sound.. so my question is.. does only fiberglass resin works or it really needs the fiberglass... cause if maybe it's the "glass" texture that stop the sound, only the resin should work.. but i don't know 

P.S. Sorry if maybe my english is bad, I made efforts 

[runmikeyrun]

it's all about volume in a speaker cab.  In a cab it makes the speaker think there is more volume.  I add it to all my bass cabs that don't already have it, adds low end.

If you're having problems with resonance you can use anything that will increase the mass of the walls, which decreases the resonant frequency.  Anything that won't melt with stage/speaker heat or crack with cold will work.  Starting with thicker/more dense wood is a good start, internal bracing is an important next step, and then use something else on the walls if you still have issues. 

[ChampiBoy]

Thanks a lot for your advise! it makes sense to me 

[ChampiBoy]

I thought making a 2x12 (mesa rectifier size) out of 1" marine grade poplar plywood (i didn't know it exist that thick) except for the front and back that would be 5/8" cause i can have it for free. Do you think it would be okay? I don't know the caracteristics of this type of wood but as it's free, i would give it a try 

[petemoore]

except for the front and back that would be 5/8" cause i can have it for free.  
  5/8ths might cut it for the baffle board, depending on the wood. If anything needs to be the thickest it's the baffleboard IMO, followed by long/wide spans of wood. because that's where the speaker pulls hard on it, also you'll be cutting large speaker holes in it.
  1'' poplar should be Morgan enough strength.
  I think non-resonant cabinets are easier to figure out [mostly non-resonant, there's always 'some' movement], resonant generally takes a plan based on trial and error, or trial and error...like this:
  Start with cabinet that's supposed to be 'resonant', if it's too resonant, stick your hand firmly across long/wide boards to see where the resonance is [where it can be reduced by hand-damping], then super securely add a 'lamination'...
  I started with 1/2'' - 5/8th's inch thick antique pine, then added a very stiff hardwood 3/4'' x 2'' ripping to the top and bottom, as well as re-inforcing the backboard [which is ported]. This started off as just a bit too resonant, ended up...just resonant, still lightweight.
 

[ChampiBoy]

So I better make it all 1" thick. (same price ) Does the back panel have a big impact on the sound/resonance?

[the_random_hero]

You don't even need 1" thick ply. 1/2" is fine for the back and front as long as you use some decent jointing techniques and bracing, use the thicker stuff for the front baffle.