pine or oak for baffle?

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See, We know that after you countersink a driver for flushmount and then you round over the back of your cutout for the rear wave, you aren't going to be left with a tremendous amount of material for your screws to grab.

What would be wrong with using solid woods for the baffle. Oak is really hard and it doesn't take much of it to hold a screw.
 
Binkstir said:
See, We know that after you countersink a driver for flushmount and then you round over the back of your cutout for the rear wave, you aren't going to be left with a tremendous amount of material for your screws to grab.

What would be wrong with using solid woods for the baffle. Oak is really hard and it doesn't take much of it to hold a screw.

I use solid woods for many of my baffles. The purists will say that resonance and directionality of the grain make it inferior to void-free plywood or MDF, but I personally am always willing to make that tradeoff because I hate veneering and hate anything other than a wood finish on a speaker.

HOWEVER, using solid wood for the reason you bring up, which is screw engagement, is a bad idea IMHO. Just use t-nuts if that's your only issue. A lot of people here ONLY use t-nuts to attach drivers, whatever the design.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=081-1090
 
Scottmoose said:
The Japanese rate pipe & spruce very highly I understand, only just behind maple. I remember Terry Cain describing pine as 'dreamy' for speaker boxes, esp. horns, providing it's of the right quality.

Interesting. Spruce and its relatives are what has been used traditionally for the tops (soundboards) of stringed instruments. Here, everyone is trying to make boxes and baffles that are dead. Makes you think....

-- Dave
 
Somehow I think that this solid woods story is based on misunderstandings and lack of knowledge. The fact that spruce is used as soundboards on acoustic guitars has nothing to do with solid wood in loudspeaker cab's. In a guitar top the thicknes is 3 mm or less, which of course wil make the panel resonate as it should, but if used in a loudspeaker, you would head for 20-25 mm, possibly even more in the baffle. MDF is not resonant free by far, and still needs damping. A solid wood cabinet will maybe need more damping, or at least more intelligent damping.

The industrial excuse for using MDF, and previoulsy chipboard, ( .. MDF is chipboard, too- just smaller chips..) has little to do with resonance, rather than material and production cost which would be extremely high using solid woods, and hardwoods in particular.

There may be an issue with solid woods in terms of expansion with temp and humidity, but I think this is possible to combat. There is a myth, or at least partial myth, that a solid wood cab will crack at the joints, but why doesn't all our table and bench tops, shelfs etc. etc crack?? OK- some of them do, but ususally after being exposed to fairly extreme temp and humidity variations. The issue lies with cross grain joints, where a possible expansion will have different coefficients in the opposing grain directions, but I still think this is possible to beat, provided the panel size is not extreme. As for any resonances, they will of course have to be dealt with, by damping and bracing. Intelligent bracing with the aim of reducing the resonance Q is the trick, not trying to remove the resonances all together.

I am possibly to embarc an a new project, most likely a full range, or treble assisted full range, like a BIB or a MLTL of some kind, hoping Scott could give me a hand, as I don't have access to MathCad.
The reason for using solid wood, is that I truly like to have a proper finish. Although I have no problems doing veneering and such, quality veneers are almost impossible to find in my corner of the world, in smaller quantities at least. A plywood- chipboard-MDF lamination with solid at the outsides is another posiibility.
 
Hi Folks,

I don't know if this is of interest.

One way to avoid solid wood from splitting due humidity etc. is to join the wood in strips about 5cms wide by a good tongue and groove joint or similar and then glueing. It works for parquette floors which are much greater in surface area and subjected to harsher conditions. I would not be too concerned with solid wood pieces up to around 6 inches in width though.

I believe the wood will still be affected by temperature and humidty(swell and contract) but the amount of expansion of each individual piece is much more consistent, because each piece is much narrower.

The changes in humidity are a major factor in how string instruments sound, also temperature. Double basses and cellos in particular for obvious reasons. I know I used to play viola for 10 years.....

Joining the wood shouldn't affect the sound either, a large number of stringed instruments have 2 piece backs. But the glue used is rather important indeed and is just important as the varnish.

cheers Stroop
 
AuroraB said:
Somehow I think that this solid woods story is based on misunderstandings and lack of knowledge. The fact that spruce is used as soundboards on acoustic guitars has nothing to do with solid wood in loudspeaker cab's. In a guitar top the thicknes is 3 mm or less, which of course wil make the panel resonate as it should, but if used in a loudspeaker, you would head for 20-25 mm, possibly even more in the baffle. MDF is not resonant free by far, and still needs damping. A solid wood cabinet will maybe need more damping, or at least more intelligent damping.

What do you suppose a guitar would sound like if it had a 3 mm thick MDF top? :D

Seriously, I think you underestimate our knowledge and understanding. I know that I understand the difference between the top of an acoustic guitar and a speaker baffle. I still think it's interesting that people with ears I respect find that spruce baffles sound good.

-- Dave
 
Dave Cigna said:
What do you suppose a guitar would sound like if it had a 3 mm thick MDF top? :D

This time of year, LOTS of stores are carrying $49 electric guitars made of just that ;)

My advice to add to this thread is stay away from laminated pine. As pretty as it is, the adhesives used are always questionable and they definately expand/shrink at a different rate than the wood. I have yet to have one that didn't split after a few months in the house.
 
Dave Cigna said:
Seriously, I think you underestimate our knowledge and understanding. I know that I understand the difference between the top of an acoustic guitar and a speaker baffle. I still think it's interesting that people with ears I respect find that spruce baffles sound good.

-- Dave
Spruce is light and stiff, so that would make it a logical candidate to me for baffles, if that was the path you were heading.
 
Things I've heard about solid wood.

Best used in small strips.

Dont glue MDF to solid wood(at least not more than 8" wide). They expand at different rates.

Coat the solid wood inside and outside with poly stain to minimize water absorption.

1.25" of solid wood plus dynomat type material is as dead as 3/4" MDF and much prettier.

Oak will resonate at a higher frequency than pine. This probably makes it worse.
 
I still save interesting posts made by people I respect on forums for future reference -GM, Martin King, DaveP10, Terry Cain etc.

Two posts Terry made elsewhere back in 2002. I know if he was able to he'd be joining in, so providing some of his previous comments on the subject that some people might not have run across before is probably the next best thing:

"It’s funny, solid wood was / is SO taboo for monkey coffins. Basically any mild hardwood with good stiffness to weight ratio that is of “cellular diffuse” grain structure. Western maple like alder has this consistent structure. Oaks and “concentric ring” type woods are too resonant, or at least they are “louder” being more resonant. I once made a xylophone with a young 6th grader where all the keys are solid wood THE SAME SIZE and the intrinsic tone made a full scale E through F with local woods only. So in a speaker as the Japanese always knew. Wood sounds good. Look at pianos, there are plenty of cheap plywood and “wood products” in newer pianos. But try to convince a player that sounds good? Older solidwood pianos have life and richness that resonant solid wood contains. Speakers that use a cabinet to increase output ie “horn loading”, benefit from the micro reflectivity of a solid wood surface and the homogenously resonant structure. Solidity and stiffness far exceed what is possible with industrial particle wood panel products. They’ll never make an airplane from spars of mdf. And in vibration control stiffness to weight is x and y. Alder has a wonderful complex grain structure that’s very concistent and works extremely well. It’s also very stable over time."

Taking this a little further...

"> > Perhaps the speaker industry has headed in the wrong direction by trying to make speaker cabinets absolutley “dead” and neutral.
=I think most japanese audiophiles and most hornophiles would agree. I certainly do. I believe this was an “overcorrection” due to the emergence of particle board in the 60’s. It sucked as furniture, and lo and behold the lowly speaker box industry found a cheap panel to make big-uns with. It fits in the sealed box/highpower requirements of the Hirsch/Houck era. Truckers must love mdf and PB, to and from speakerplants. Anyway I think we definately got carried away with the dubious “positive” aspects of composite wood panels in the name of “saving forests. Now mdf is so ubiquitous that things like “hand tools” are long forgotten tools for building. Automated panel stackers feeding automated hot melt edgebanding and CNC routers build 99% of all wooden audio products.
> > But, maybe we are losing some of the “life” by not taking advantage of the inherent resonant character in natural wood to give audio presentation a more real and textured feeling. =Takes wood to make wood IMHO. Resonant sound is just that. Coming from a cello or a speakerbox. Interesting that some of the very best speakers in the world use polymer and graphite composites, kevlar etc. Seemingly in order to mock the characteristics of wood.


Interesting stuff from probably The Master cabinetmaker.
Scott
 
Thank you , Scott - and AMEN.

There are some strange myths presented in some of the previous posts, though...

Guitar with 3mm MDF top - of course not usable, because you WANT the guitar top to resonate, - but do some reading about lutherie, and you will find that it does not take much increase in thickness, or making the top bracing to heavy or too stiff , - and you've killed the most beloved resonances you were seeking.
Cumpiano / Nathelson - "Guitarmaking -tradition and technology" will give you some insight to when resonaces are wanted.

"Stay away from laminated pine. As pretty as it is, the adhesives used are always questionable and they definately expand/shrink at a different rate than the wood. I have yet to have one that didn't split after a few months in the house."
I don't know about american lam boards, but the ones we get over here are properly made, and I have yet to see one split under normal indoor conditions. Also, if this was true, I wouldn't touch plywood even with large tongs.....

"Dont glue MDF to solid wood(at least not more than 8" wide). They expand at different rates"
Glue alone won't do the trick. Glue and screw is the clue..... ( NB.metal screws that is...)

"Best used in small strips"
Sometimes right, - that's why lam boards are used, - to combat the grain forces of improperly cut wide panels. That's why luthiers looks for quarter sawn woods,- although the icon of rock guitars, Fender, uses mostly all flatsawn woods.

"Coat the solid wood inside and outside with poly stain to minimize water absorption"
That's actually a very good idea, also for MDF and chipboard. Even more so if you live in an area with very high variations of humidity.

And so on and so on...
Sometimes I really wonder where and when this MDF road to heaven started. Some years ago there was a genreal concensus that it was mostly for ease of production, even for the DIYer, not as much for the acoustical merits of MDF or chiboard, as they very clearly have issues of their own.

All this said, there are definately some issues using solid wood for cab's- crossing grain joints, expansion, panel resonances etc. You may want to make use of the panel resonances, as some people do, -or you can combat them. It's all about the mechanical Q of the panel, - how to reduce the Q and shift the resonances to where they don't hurt - in a multiway speaker. This means damping layeres, diagonal bracing, compound lam's etc.
Martin Colloms book " High performance loudspeaker" have a very intersting chapter about panel resonance modes and how to combat them.

Why would we want to use solid wood anyway ???? FOR THE LOOKS OF IT !!!!
I seriuously don't mind a 1.5 dB hump if that's the price for looks to die for! I actually take some pride in trying to live in a home - not a lab!

I think I'll end my part here. We have seen this debate before, and it actually have quite alot of resemblance to the infamous cable debates.
All to his own taste.. you'll have yours and I have mine! :D
In most cases, if you're looking for WAF , try some nice wood panels! ( I'm acutally looking quite seriously into the combination of the sorts, each "specie" counting for it's own advantage )
 
For what its worth, I totally agree.

Maybe it would be enough to know which species sound best and how much better than MDF or ply and at varying thicknesses, if at all. I love the idea of a speaker being an instrument of sorts!

My father instilled in me, my love for solid timber for anything and everything. It simply looks beautiful, is honest all the way through, not to mentional it smells great and feels great! I wonder if I can convince him to make some solid red cedar BIB's....I'm sure he's got some lying around...

P.S.- JVC has brought out wooden speaker cones.

Cheers Stroop
 
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