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Old 23rd March 2007, 03:19 AM   #1
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Default Discussion on what materials to build speakers out of

Quote:
Originally posted by ruerose
Finally, I don't have access to decent (for my taste) no-void ply, just MDF and laminated 1x2 Project pine boards in 16" widths.
Where in BC are you that you can't get BB?

I'd use the pine before i used the MDF.

dave

Edit: 02-dec-09 (some of this is easier to wade thru if you read this post 1st)
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Old 23rd March 2007, 04:25 AM   #2
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Okanagan, I have a someone looking for some decent no-void for me, but in the end the price will dictate what I can end up using.

When I worked in building supplies a short while back, the decent stuff was a more than I cared to pay, especially since it would be just a single sheet. Seems everyone up here just stocks what is needed to build houses and make kitchen cabinets.

I really hate the voids (black spots, gaps) that will happen when I roundover the side baffles (cosmetic). I'd rather not use edge veneer as that would be a new experience for me and I do want a roundover (full roundover inside the throats).


Thinking...

I suppose I could waste a bit of wood getting a cut that has no voids along the whole line, but the dark spots will probably still bother me. Mabye my expectations of no-void are too high. But hey, this is cosmetics, no point being disapointed in the look before I even start. Hence the MDF and gloss white, at least it would have high WAF and hide then.
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Old 23rd March 2007, 05:03 AM   #3
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The point of void free isn't cosmetics but sonics. Even shop grade BB has potential cosmetic issues. Even spending 3x as much on architectural grade doesn't guarantee the cosmetics (althou it goes a long wayd)

Can't someone order you in some (it is going to take more than 1 sheet to fo Calhoun). Given driver cost & your time to do the boxes, it seems a shame to compromise by using MDF,

Pine would be interesting thou -- and you said it was laminated, so that should help as far as the usual problems with solid go.

As to doing a round-over on anything but the external edges, i'd be hesitant. Part of the design is the discontinuities.

dave
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Old 23rd March 2007, 05:17 AM   #4
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There's another problem with voids that all speaker builders should be aware of: there might be loose material in the void that will vibrate and buzz along with your music.
Use the MDF already.
NEVER in a million years would I ever use solid wood to build a speaker. Probably the worst choice ever.
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Old 23rd March 2007, 05:36 AM   #5
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I used Project pine for some cabinets, it is more than MDF ($20 for a 16"x4' piece vs $30 for a 4x8 3/4") but there is a large batch to pick some interesting grain patterns out of and minimize the knots.

Because of the lamination though, cutting with the grain is more of a chore than ply.

If a roundover on the inside edge isnt recommended, is a small bevel a good compromise?
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Old 23rd March 2007, 05:38 AM   #6
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Quote:
Originally posted by MJL21193
solid wood to build a speaker. Probably the worst choice ever.
Not so. Scott has built some fantastic speakers of solid fir, GM has used pine boards (as have a number of others on the FR Forum). At least a few hi-end commercial speakers are made of solid.

It is true that solid wood requires the most care & attention when building. In this case he is talking laminated pine boards not solid.

MDF just seems to suck the life out od a speaker. If you have to at least use medite (HDF)

dave
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Old 23rd March 2007, 05:44 AM   #7
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Quote:
Originally posted by ruerose
If a roundover on the inside edge isnt recommended, is a small bevel a good compromise?
One of the intentional design features of this kind of cabinet are the sharp corners. The deflector could be made of a single piece, bur the only place wher you might be able to put a bevel is the edge at the transition from the straight section of the port to the bell.

dave
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Old 23rd March 2007, 05:44 AM   #8
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Solid fir...mmmmm that sounds seductive.

You coasters get all the good stuff. Up here in this dry clime fir likes to do the magic bending spoon trick.
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Old 23rd March 2007, 06:13 AM   #9
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http://www.hardwoods-inc.com/Products/dragonply.cfm

Project pine might be as expensive in the end as a decent ply. I'm going to get some pricing and decide which way I want to go.
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Old 23rd March 2007, 06:36 AM   #10
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Quote:
Originally posted by ruerose
Solid fir...mmmmm that sounds seductive.

You coasters get all the good stuff. Up here in this dry clime fir likes to do the magic bending spoon trick.
The particular fir Scott uses came out of a railroad trestle built in 190-something, so it is old growth and has had a 100 years to age.

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Old 23rd March 2007, 10:10 AM   #11
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Solid wood worst choice for speakers?!? I think not. It depends on your material knowledge, but anything with a tight grain and high stiffness / weight ratio should beat MDF hands down. Look at Terry Cain's creations -I suppose the now pretty distant original inspiration for Calhoun. Fir and pine, if treated right according to Terry, are amongst the best materials for horns or their variations, so long as the moisture is low. Love that idea. GMs pine came from an old barn door I believe, ~150 years old if memory serves, and had similar properties to aluminium after aging for that time.

Roundovers go somewhat against the design intentions, which is to deliberately have the sharp edges, but as Dave says, if you want to, the the transition of the initial port to the bell-flare is the place to put them.
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Old 23rd March 2007, 10:38 AM   #12
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Solid wood is a problem when it comes to wide panels, the expansion and contraction may cause cracking and joints to open up. I personally wouldn't use panels any wider than about 10-12" maximum.
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Old 23rd March 2007, 05:31 PM   #13
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I just about made the Calhoun's with the pine board. The boards (pine shelving) at Home Depot showed enough twisting that I thought the better of it. If I had enough clamps it would have been fine but I was using a finish nailer and that doesn't provide enough strength to suck the two pieces together so I made it from Maple plywood and the horns from MDF. The horns were made of MDF because it comes as a 3/4" board where as the ply is now metric and measures 23/32"

It was all done in modules. The horns and inside cabinets were made ahead of time then simply slapped the sides on.

EDITED: Overstated the obvious
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Old 23rd March 2007, 10:35 PM   #14
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Quote: "Solid wood is a problem when it comes to wide panels, the expansion and contraction may cause cracking and joints to open up"

pinkmouse: My hat's off you, once again the voice of reason.
Is this a DIY forum? Yes, solid wood can be used to build speakers, but it must at a stable moisture content. How does the average DIY guy know if his laminated spruce panel is at 4% moisture? I'm pretty sure a reliable moisture meter is no in the DIY toolbox. Also solid wood should be sealed on all sides to maintain the moisture content. It's more expensive. Three strikes, you're out.
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Old 23rd March 2007, 11:03 PM   #15
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4% hmmm, I actually do have access to a moisture meter. (floor layers use it on hardwood)
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Old 23rd March 2007, 11:51 PM   #16
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ruerose: I have access to a scalpel, that doesn't make me a surgeon.
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Old 24th March 2007, 12:01 AM   #17
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I have access to people who know how to use it to. And besides its a moisture meter, not the space shuttle.

It's just one more tool I can use the check the practicality of useing that pine shelving.
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Old 24th March 2007, 12:13 AM   #18
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I don't mean to offend you, it's just using solid wood ( even laminated ) is not a very good choice. It's sonic properties are not consistant, it's prone to warpage and movement.
Do your self a favour and do a Google search for: "use solid wood for speakers" and read some of the results. My bet is that the result will not be encouraging.
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Old 24th March 2007, 12:58 AM   #19
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MJ -do yourself a favour and read everything Terry Cain ever wrote on the subject of solid wood and speaker cabinets. You might find it of interest. Admittedly TC was the God of materials, but his lessons are worth learning. GM's remarks on the subject too are most enlightening. Solid woods offer many potential benefits -like cabinet design, it's a matter of learning what they can offer, and utilising them correctly.

Example: a BIB could be usefully constructed using solid walnut side-panels, pine internal baffle and rear, and alder front. We use the different properties of the materials to suit what we want each to do. For man-made, change that to BB ply for the sides, particle-board for the inner and rear baffles, and a lamination of MDF and ply for the front baffle. It won't be as good as the solid wood though. Or look as good come to that. True, you have to know how to work with the solid woods, but that's no great trial -it's a fascinating subject I'm working on at the moment.
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Old 24th March 2007, 01:09 AM   #20
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Guys, chill. This is supposed to be fun, you know?
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Old 24th March 2007, 01:25 AM   #21
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scottmoose: I have worked with solid wood all of my life, and for the part 25 years professionally. I have built a hugh number of things with solid wood, so I know exactly what it will do.
When I get the opportunity, I will read everything by Terry Cain, not because he has anything to teach me about wood, but for my own personal amusement. I'm always interested in the spread of misinformation.
What I am saying here is that this is suposed to be a DIY forum, not the prestigious League of Elite Speaker Constructors. Rookie box builders shouldn't mess with solid wood for speakers. They also shouldn't be bullied into thinking that they will get inferior results by using a cheap material like MDF. Ever hear of Tony Gee? What, are all of his efforts garbage because he uses MDF?
I don't think so.
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Old 24th March 2007, 01:27 AM   #22
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Err, Terry was first and foremost a DIY enthusiast. That's how he started, and remained to the end. He sold speakers for sure. That was his dream, after 3 decades of building fine furniture. His tragic death last December robbed us all of a good friend.

No acrimony intended on my part Al. Sorry it came over that way to you, or anyone else, and any unintentional offense I caused I apologise for unreservedly.



edit -I removed anything from this post that might have been construed as having a personal reference. As noted above, none was intended.
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Old 24th March 2007, 01:47 AM   #23
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As you know, I am fairly new to this forum. I joined to engage in conversations about one of my favourite topics: audio. It seems that here, unless you ask a question that all of the "experts" can weight in on, you are ignored. No one wants your opinion, they just want to answer your question. Some of the answers are wrong, I should bite my tongue?
A man walks into a bar where no one knows him, does that mean he knows nothing?

I'm having fun pinkmouse
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Old 24th March 2007, 01:50 AM   #24
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Quote:
Originally posted by MJL21193
A Some of the answers are wrong, I should bite my tongue?
Definitely not, but we ask that disagreements are kept on a technical level, not personal.

Quote:
I'm having fun pinkmouse
Good!
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Old 24th March 2007, 02:11 AM   #25
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I limit myself to a little good natured ribbing

scottmouse: I got you fired up? It was good though? something to look forward to in the next post! Best wishes.
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