MDF or Baltic Birch???

[walter duque]

What makes a better speaker cabinet??? A cabinet build with MDF or (13 ply 19 mm Baltic Birch which mine are made of).

 

[slipperybidness]

Bamboo

I think there are a couple cabinet builders on here (as in the pro builders) that will come along and offer some insight.

 

[highfigh]

Both work well- if weight is an issue, Baltic Birch is a good choice. In any case, bracing is needed to prevent vibrations that don't help performance. Until MDF became more commonly used, particle board was the main material, with a few notable exceptions like Klipsch.

 

[TheWarrior]

MDF!

 

[TheWarrior]

MDF is much better at creating a non resonant enclosure. Obviously that then falls on to the builders shoulders to not make a poor design, but especially if you are making anything larger than a bookshelf, you want a good solid enclosure.

 

[walter duque]

I am not 100% sure, but the front and rear panels are made of MDF??

 

[KEW]

I do not believe the differences are that great. Baltic Birch Ply will not have the voids of standard plywood (which you do want to avoid). The alternating direction of the grain provides dimensional stability and offers stiffness in both directions.
MDF is easier to machine (but the dust sucks!). A good thorough clean up is needed before having drivers closeby, but you should do that with ply as well, just on principle.
BB Ply will suffer water damage better, but hopefully that will never be an issue (don't let your wife use speakers for plant stands...actually that is a damn good upgrade strategy - add a "guilt subsidy" for your replacement speakers!).
In theory, mdf is better because it is homogeneous, but I do not believe the difference is great enough to worry over. BB is solid and not very resonant.

I'm guessing their choices were more manufacturability than anything else.
They may have bought the side panels prefinished and only need to apply veneer to the front and back edges of the ply.

The baffle is not fun with BB because when cutting out the circular holes, you have to worry about cutting against the grain as the router direction changes over 360 degrees.
If you're not sure what I mean, just imagine whittling at the point of a pencil except you have to draw the blade from the point up. The knife will try to get under the grain and you will have little control, and the wood is liable to split or tear-out.

 

[walter duque]

I'm guessing their choices were more manufacturability than anything else.
They may have bought the side panels prefinished and only need to apply veneer to the front and back edges of the ply.

Everything is made in house so there are no prefinished panels. They are not veneer they are automotive paint.

 

[TheWarrior]

If you're not showing the grain, then using plywood is a complete waste of time and money. A similar thickness of MDF whether domestic or imported will be cheaper. And require less time sealing because there's no grain to hide.

 

[Alex2507]

I would rather use plywood because it's lighter and cutting into MDF sucks. I know TLS is into MDF.

 

[AcuDefTechGuy]

I don't think any cabinet is as good as the B&W 800 Diamond, and it has MDF.

 

[TheWarrior]

I would rather use plywood because it's lighter and cutting into MDF sucks. I know TLS is into MDF.

Just use an old blade! Hell, I've probably got one in every size laying around I can send you!

 

[highfigh]

I do not believe the differences are that great. Baltic Birch Ply will not have the voids of standard plywood (which you do want to avoid). The alternating direction of the grain provides dimensional stability and offers stiffness in both directions.
MDF is easier to machine (but the dust sucks!). A good thorough clean up is needed before having drivers closeby, but you should do that with ply as well, just on principle.
BB Ply will suffer water damage better, but hopefully that will never be an issue (don't let your wife use speakers for plant stands...actually that is a damn good upgrade strategy - add a "guilt subsidy" for your replacement speakers!).
In theory, mdf is better because it is homogeneous, but I do not believe the difference is great enough to worry over. BB is solid and not very resonant.

I'm guessing their choices were more manufacturability than anything else.
They may have bought the side panels prefinished and only need to apply veneer to the front and back edges of the ply.

The baffle is not fun with BB because when cutting out the circular holes, you have to worry about cutting against the grain as the router direction changes over 360 degrees.
If you're not sure what I mean, just imagine whittling at the point of a pencil except you have to draw the blade from the point up. The knife will try to get under the grain and you will have little control, and the wood is liable to split or tear-out.

How much it splits and tears out depends on the bits- if they use straight bits at high enough speed, it's not bad but if they use spiral bits with sacrificial backing, it shears the fibers as it rotates and that produces a cleaner cut. An easy way to have extremely clean edges is to round them over or chamfer after routing the holes.

http://www.carbideprocessors.com/2-flute-deep-mortise-upcut-bit-1-2-dia-1-1-2-cut-length-1-2-shank-vortex-2325/?gclid=COLCq-bCv8UCFUg6gQodcGAAeg

These come in up-cut and down-cut. For a clean edge when routing dados/grooves, mortices and other slots, down-cut is used and when chipping out at the back doesn't matter, up-cut is better.

 

[highfigh]

My uncle built a pair of speakers in the '50s, using thin material, good bracing and he created a space between the inner and outer parts, filling them with sand. They sounded great. IIRC, Wharfedale did that and he may have gotten the idea from reading about theirs.

 

[Alex2507]

Just use an old blade! Hell, I've probably got one in every size laying around I can send you!

I'm all stocked up on old blades but thanks anyways.

Seriously, I'm at a loss as to what an old blade would do for me except maybe burn the wood. It's the dust and weight I object to. Not as big a detractor is the way it swells when wet. I know you don't want to get it wet but sh!t happens. I've only ever built a pair of subs and I used an odd combo of free ply and particle board because good ply was a little too dear at the time. Read: if I have time to build then I'm too broke from not working to be buying fancy ply.

Walter, ask John why he uses the BB as opposed to MDF. I'd be interested in his answer.

 

[TheWarrior]

I'm all stocked up on old blades but thanks anyways.

Seriously, I'm at a loss as to what an old blade would do for me except maybe burn the wood. It's the dust and weight I object to. Not as big a detractor is the way it swells when wet. I know you don't want to get it wet but sh!t happens. I've only ever built a pair of subs and I used an odd combo of free ply and particle board because good ply was a little too dear at the time. Read: if I have time to build then I'm too broke from not working to be buying fancy ply.

Walter, ask John why he uses the BB as opposed to MDF. I'd be interested in his answer.

Well, fellow Alex, come on down to GA and I'll show you how to use my Festool setup!

Or take a circular saw and if you have any type of shop vac, rig it some way (duct tape) that the hose can follow the saw. Table saw would make it even easier, of course!

The saw blades, as long as they're not rusted, would slice through mdf with ease. Its your perfectly straight cutting that will keep the blade from burning the wood, regardless of blade sharpness.

MDF seals easily with a mixture of wood glue and water, too, btw!

No time eh? Maybe I need to start the Audioholics custom shop... lol

 

[Speedskater]

For a full range speaker use MDF.
For a sub-woofer use Baltic Birch.

The non-resonant properties of MDF only come into play at higher than sub-woofer frequencies.

 

[Alex2507]

Well, fellow Alex, come on down to GA and I'll show you how to use my Festool setup!

I've actually used a Festool set up to undercut doors. Even after you get past the dust with MDF, you still have the weight problem ... and you never get past that dust. I can still taste it from last year.

I've got basic woodworking covered. With MDF you want the vacuum and you want to be outside and you want to be away from anything you don't want the wind to plaster with that crap. However the advantages of MDF can't be denied. It is easy to cut, it's cheap, it's stable. I just happen to hate it.

For a full range speaker use MDF.
For a sub-woofer use Baltic Birch.

The non-resonant properties of MDF only come into play at higher than sub-woofer frequencies.

I think a properly braced cabinet would sound similar in either medium. Even supposing that the difference was easily audible once you knew what to listen for, I'd still take the lighter and more expensive ply cabinet. Such is my contempt for that glued up mess.

A ply cabinet would be less prone to being damaged under it's own weight. I'm talking like I have the money to afford the step up in price (I don't). Speaking to Walter's question, even though MDF has acoustic advantages, I would still choose ply.

 

[Steve81]

I think a properly braced cabinet would sound similar in either medium.

Ditto. I don't see any JTR & Funk owners (both of which use BB for their speakers & subs) complaining about cabinet resonance.

 

[walter duque]

Walter, ask John why he uses the BB as opposed to MDF. I'd be interested in his answer.[/QUOTE]

John uses only MDF on his speakers. As you know he is the OEM for the speakers I have now. That's how their customer ordered them and that's what he did. They got rejected because there is a very fine (but perfect line on the subs tops. You have to get very close to even see it.
As you know they are automotive paint, could have come from taping it off or they glued two pieces of board together and didn't wait long enough for the glue to dry. Anyway I am happy with them. I couldn't even get a pair of good towers for what I paid for the whole 7.2 system.