This is an elementary question but I am no master woodworker by any stretch,What is the best way to fuse two panels together if I want to go 2 ply with 3/4 for the walls to get 1 1/2 inch thick walls thinking 1 1/2 inch ply may be more of a challenge to find. Figuring maybe 1 1/2 for cab and 3/4 for bracing.
FEA and crossovers
About this same time a friend of mine and I went to visit Dave Focus of Icon Acoustics and had a very interesting conversation. He was working on non-parallel cabinet sides with a slanted front baffle. He said, "Speaker system design, especially the crossover is very complicated and one cannot with current models use just equations and computers." He was adjusting crossovers to correct for phasing problems.
As I recall, through the bass driver mounting hole. I don't recall if it included a through-the-air component but it probably did.
Determination of better was less vibration. We couldn't determine how this affected the actual sound results.
About this same time a friend of mine and I went to visit Dave Focus of Icon Acoustics and had a very interesting conversation. He was working on non-parallel cabinet sides with a slanted front baffle. He said, "Speaker system design, especially the crossover is very complicated and one cannot with current models use just equations and computers." He was adjusting crossovers to correct for phasing problems.
I found a local lumber yard Woodhaven in Point Pleasant that can order me 1" baltic birch plywood in 5x5 sheets for $80.00 a piece so looks like I am good
Great price... Be sure your getting what you want and not regular plywood with a birch face. The regular 1" ply I get has 7 layers in the core plus a thin veneer on each side. The 3/4" BB ply I have is 13 plies all the same.
While Evan's cautionary note is well advised, I think the 5x5 sheet size likely indicates this would be a "true" Baltic Birch ply -a nominal 1" thick sheet would have 17 plies.
Also note that the grading of imported materials can range quite a bit in terms of quality of face veneers. Most of the 5x5 's I've sourced for well over 10 yrs have been a C face / shop grade, as they're normally used in the trades to fabricate frames for upholstered furniture or as a substrate to be veneered or laminated with plastic. This means they are structurally sound, but subject to any combination of unfilled small pin-knot holes, larger filled or foot-ball patched knots, and mineral stains. None of these will affect the integrity of a build, but can certainly add time and complications if you're planning on finishing the raw surface with clear coat or even semi-transparent stains.
As to construction, I think 1" BB ply is overkill for all but mondo subs, or if details such as staggered baffles on some of Troels Gravesens' designs are involved. I've found well braced 15 or 18mm to be quite adequate for all my builds.
Bracing and panel resonance damping, etc are a whole 'nother can of worms, about which I think consensus will be hard to achieve - no doubt there are exhaustive studies and measurements that can be used to buttress arguments for any of numerous approaches.
Also note that the grading of imported materials can range quite a bit in terms of quality of face veneers. Most of the 5x5 's I've sourced for well over 10 yrs have been a C face / shop grade, as they're normally used in the trades to fabricate frames for upholstered furniture or as a substrate to be veneered or laminated with plastic. This means they are structurally sound, but subject to any combination of unfilled small pin-knot holes, larger filled or foot-ball patched knots, and mineral stains. None of these will affect the integrity of a build, but can certainly add time and complications if you're planning on finishing the raw surface with clear coat or even semi-transparent stains.
As to construction, I think 1" BB ply is overkill for all but mondo subs, or if details such as staggered baffles on some of Troels Gravesens' designs are involved. I've found well braced 15 or 18mm to be quite adequate for all my builds.
Bracing and panel resonance damping, etc are a whole 'nother can of worms, about which I think consensus will be hard to achieve - no doubt there are exhaustive studies and measurements that can be used to buttress arguments for any of numerous approaches.
I wonder about the longevity of various materials. My beloved Infinity Monitor IIas were made of MDF, and, after 40+ years it is pretty crumbly. I bet the plywood holds up better, but I'm only guessing.
Chris is correct. I missed the 5'x5' part. I'm going to have to see about buying my plywood there.
My money's on the plywood for longevity.
My money's on the plywood for longevity.
Environment conditions as well as handling can certainly come into play, but many of the high volume commercial speaker boxes from early 70s forward that I've seen, owned, and been asked to "repair" (= rebuild) were fabricated with a quick and nasty V-fold and hot glue method, with minimal if any glue block bracing or cleating - which does not ensure a structurally rugged enclosure. FWIW some of the best built boxes for the money that I personally owned were the early EPIs - Model 50, 100 and 150s - the first painted and vinyl wrapped Microtower series were a different story
Wonder if the MDF of the 70's is different to the present day ones ?
There's conti-board as well , which for simple boxes is excellent as its melamine surfaced both sides and there's a lot of choice in coverings.
Because we have a lot of bespoke kitchen and bedroom manufacturers around the city I have found quite a few suppliers. And so far ( for my small cases) I have priced an 8' x 6" board for £5.20 in black oak. I think there are various manufactures and I don't have any specific density's etc but its heavy and at the last count there was over 30 finishes to choose from including about 4 gloss colors.
Edging (iron on) was 30p a meter. The added bonus is , when the edges are sealed very little moisture can soak in. ( so the guy at the wood yard said lol )
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Actually a lot of those 70's boxes were particle board as often as MDF, but yes, the quality and composition of engineered sheet goods have changed more than a little bit in the last 45+yrs
I used to build loudspeaker cabinets with chipboard in the 1980's.
They sounded OK.
I use 18mm plywood now and cant tell the difference.
They sounded OK.
I use 18mm plywood now and cant tell the difference.
B&W 801/802's
To my shock - B&W 801 and 802's atleast the S2 and S3 sets were OSB - Oriented Strand Board (I think chip board or particle board are different names for that right).
Sonically the yare pretty dead. MDF and all the rest are similar.
The difference is - how well it stands up to your life and how well can you repair it if it needs it.
My second 802 had some delamination due to ... ahem ... UPS's aided delamination lets call it. It was a nightmare to repair it.
So that is where it matters. Plus, plywood is lighter than MDF. May be a good thing, where you can always weight it and stuff it more for the same weight.
Cool.
Srinath.
To my shock - B&W 801 and 802's atleast the S2 and S3 sets were OSB - Oriented Strand Board (I think chip board or particle board are different names for that right).
Sonically the yare pretty dead. MDF and all the rest are similar.
The difference is - how well it stands up to your life and how well can you repair it if it needs it.
My second 802 had some delamination due to ... ahem ... UPS's aided delamination lets call it. It was a nightmare to repair it.
So that is where it matters. Plus, plywood is lighter than MDF. May be a good thing, where you can always weight it and stuff it more for the same weight.
Cool.
Srinath.
Hi,
Before MDF came along the budget choice was flooring grade chipboard.
Real rough edges and a saw blade sharpness killer, good stuff though.
rgds, sreten.
Before MDF came along the budget choice was flooring grade chipboard.
Real rough edges and a saw blade sharpness killer, good stuff though.
rgds, sreten.
one of these things is not like the other
OSB
particleboard / chip board
frequently factory laminated with plastic ("melamine") or real wood veneers
In the 60's or so the particleboards sold hereabouts were referred to as K3, and had an amazing affinity for absorbing moisture, swelling, and falling apart. The modern adhesives used is certainly one of the areas of improvement in the general class of engineered sheet goods.
OSB
particleboard / chip board
frequently factory laminated with plastic ("melamine") or real wood veneers
In the 60's or so the particleboards sold hereabouts were referred to as K3, and had an amazing affinity for absorbing moisture, swelling, and falling apart. The modern adhesives used is certainly one of the areas of improvement in the general class of engineered sheet goods.
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I used some OSB subflooring for a trial cut on a Shopbot since it was cheap
it is amazingly bad stuff - only finished flat on one side, thickness varied 1/16" across the panel
the unfinished side wood splinters and chips pulled out with the doublesided tape used to hold the work to the Shopbot bed
and the OSB literally stinks - pine sap and glue made my eyes water driving it home, still stank months later
it is amazingly bad stuff - only finished flat on one side, thickness varied 1/16" across the panel
the unfinished side wood splinters and chips pulled out with the doublesided tape used to hold the work to the Shopbot bed
and the OSB literally stinks - pine sap and glue made my eyes water driving it home, still stank months later
one of these things is not like the other
OSB
particleboard / chip board
frequently factory laminated with plastic ("melamine") or real wood veneers
In the 60's or so the particleboards sold hereabouts were referred to as K3, and had an amazing affinity for absorbing moisture, swelling, and falling apart. The modern adhesives used is certainly one of the areas of improvement in the general class of engineered sheet goods.
My 802 cabinet was somewhere between the 2. Likely it was the lower one in the second pic.
It did delaminate and disintegrate with water a good bit, but I pretty much filled up all the possible spots with liquid nails extra strength that was drying in the tube a year or so, it was the consistency of peanut butter and glued like a gorilla and clamped the sheet back till it resembled a sheet again.
Cool.
Srinath.
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