Stuffing increases apparent box size, correct? If I have an unlimited supply of free 0.5" plywood, should I stuff my box, or just build as big of one as I can? Thanks
You shouldn't build a box out of 1/2" ply. The minimum would be 3/4" and even thicker is preferable. Also, the plywood should be a quality grade without voids.
If it's 1/2" marine (void free) ply, then you could always glue 2 sheets together with liquid nails or the like.
Standard Materal
The standard material for speaker cabinets is MDF not plywood. Plywood is will flex and generate resonance frequency, where MDF is not more dense and will not. Of course you would use 3/4 MDF and brace the cabinet with a hard wood like oak, birch, maple. The hardwood connected to opposing sides and help the speaker cancel out internal resonances.
The standard material for speaker cabinets is MDF not plywood. Plywood is will flex and generate resonance frequency, where MDF is not more dense and will not. Of course you would use 3/4 MDF and brace the cabinet with a hard wood like oak, birch, maple. The hardwood connected to opposing sides and help the speaker cancel out internal resonances.
The size of the box will depend on the speaker you're going to use in the box. Typically, a sealed box will be full of stuffing and a ported box will be lined on all sides.slackerbob said:
BTW, are you by chance related to Dan Quayle?
If you have an unlimited supply of the 1/2", even if it is low quality, you could try gluing 3 or 4 layers together. One way would be to build a box out of 1/2", then build another box glued to the first and screwed at the edges to itself and to the one underneath. Do the same with the third and maybe a fourth. This way, you should end up with something pretty solid.
Filling a sealed enclosure not only lowers the cut-off frequency of its response, but also smooths out the response. I like using polyfill from cheap bed pillows. Tht is the easiest way to purchase quite a bit of it.
Filling a sealed enclosure not only lowers the cut-off frequency of its response, but also smooths out the response. I like using polyfill from cheap bed pillows. Tht is the easiest way to purchase quite a bit of it.
It used to be a truism that MDF was the best. Quite a few people now seem to prefer plywood over MDF I made my bass box of 2 layers of 3/4" ply glued together, and it is SOLID. I think 2 layers of 1/2" ply will be just fine. I used a harder glue than Liquid NAils, between the layers, but in retrospect, the LN would damp better.
slackerbob said:
I'd stuff it; the bigger your box is the more problems you'll have with resonance.
If you're doing this on the cheap - in the past I've used rubber carpet underlay glued onto the internal panels, and fibreglass roof insulation as stuffing. I found it was significantly better than nothing at all, and virtually free.
Cheers
IH
Speaker Stuffing and Material
You should only stuff you box along the wall of the enclosure then measure and listen to the results. If you don't like the feel the performance is adequate then add more batting. With most designs, you can over stuff, this will cause a loss of bass. The loss of bass is caused by over damping the driver changing the system Qt, causes a thermal resistance or a repelling force. A very dense fill can increase the friction losses in the enclosed air volume and augment the damping. Also, with a light diaphragm and a dense but flexible filling, the effective cone mass increases by as much as 20%.
So is best to not over damp your enclosure and listen to or measure the effect of the damping. Also the standard for enclosure material is MDF not plywood. Plywood speakers cabinets date back to the 1940 and MDF is a much new material and will resonate at a much lower frequency.
You should only stuff you box along the wall of the enclosure then measure and listen to the results. If you don't like the feel the performance is adequate then add more batting. With most designs, you can over stuff, this will cause a loss of bass. The loss of bass is caused by over damping the driver changing the system Qt, causes a thermal resistance or a repelling force. A very dense fill can increase the friction losses in the enclosed air volume and augment the damping. Also, with a light diaphragm and a dense but flexible filling, the effective cone mass increases by as much as 20%.
So is best to not over damp your enclosure and listen to or measure the effect of the damping. Also the standard for enclosure material is MDF not plywood. Plywood speakers cabinets date back to the 1940 and MDF is a much new material and will resonate at a much lower frequency.
While this is true, it's important to note that not just any plywood should be used. Birch ply, applewood, marine grade, etc. , are examples of void free plywood. I built a sub using marine grade oak plywood with MDF braces. Turned out pretty good. Definitely more expensive than plain MDF though.
id' build 2 boxes one slightly smaller than the other (so there is about 6mm or 1/4" difference between the outer dimensions of the smaller box and the inner dimensions of thebigger box). only the baffle will be common.
the smaller box will house the drivers. the space between the 2 boxes can be filled wiht DRY sand, lead, foam etc...
also you should/could brace the inner box (compensate for the volume of the bracing when calculating Vb).
the smaller box will house the drivers. the space between the 2 boxes can be filled wiht DRY sand, lead, foam etc...
also you should/could brace the inner box (compensate for the volume of the bracing when calculating Vb).
_______tip toe in here....had a piece of 1" sign board plywood in my pickup for about 8 years...my friend said it was made to withstand the weather [unpainted]....took it out and cut a piece off...I was amazed...Looked like new!...I ended up building some speakers out of the rest of the sheet...bass bins I should say and the band still use them today...go figure
DIRT
DIRT
Sand
Well I always use fiber fill and spary foam in the hard to reach spots. But that's not what to talk about i'v heard about a guy using sand to fill his cabinets with sand and paking it tight...Now i searhed i could not find anything here about using sand..what would be the outcome??? i'm not an expert but if had the stuff to build a prototype i would....
Well I always use fiber fill and spary foam in the hard to reach spots. But that's not what to talk about i'v heard about a guy using sand to fill his cabinets with sand and paking it tight...Now i searhed i could not find anything here about using sand..what would be the outcome??? i'm not an expert but if had the stuff to build a prototype i would....
If you are going to use sand, you have to make a box within a box and then fill the gap between the 2 with sand.
well, since my woodworking skills aren't the greatest, i think glueing 2 sheets together before messing around with putting the box together would be the best way for me to go. the last boxes i built had 2-4mm cracks all the way around the front and back panels. I think i'll be a bit more careful with measuring this time too. Thanks for all your input.
There was a trend in the UK hifi press a few years ago to pull the stuffing out of LS enclosures. They finally got round to testing it and the opinion was that below 400Hz or so, the boxes sounded better unstuffed. I tried it with my Jordan speakers (which cross over at 500Hz) and prefer the bass box unstuffed (it's a sealed box) but with lining on the interior walls.
Re plywood - after messing about with MDF for a while, it was a relief to go back to plywood; a lot easier to work with. I think MDF has become the standard because manufacturers find it easier to machine. (There's even a move back to chipboard enclosures amongst one or two upmarket speakers.) As regards the sound, it may be down to whether you're of the light and stiff enclosure school or the heavy and dense. Either will hum along to the music - they just do it at different frequencies and for longer periods after the music stops.
Colin
Re plywood - after messing about with MDF for a while, it was a relief to go back to plywood; a lot easier to work with. I think MDF has become the standard because manufacturers find it easier to machine. (There's even a move back to chipboard enclosures amongst one or two upmarket speakers.) As regards the sound, it may be down to whether you're of the light and stiff enclosure school or the heavy and dense. Either will hum along to the music - they just do it at different frequencies and for longer periods after the music stops.
Colin
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