Solid Wood?

[Lewis Moon]

OK, lets get this out of the way first....I'm a complete N00B. I've been listening to Jazz, freakfolk etc on good to great (Grado/Alessandro) headphones for a while and I realized that the old Bose 301 bookshelf speakers (clean the coffee of your keyboard) weren't cutting it....at all.
I want to build a set of speakers because...I spent all my dosh on my (multiple) headphones. I was thinking about the Lyra TMW over at Speakerbuilder.net... Other suggestions?
Specifics: The room is about 15 X 23 with nine ft. ceilings, I like detail a LOT and the speakers need to have a fairly small footprint and basically be pieces of furniature.
Can I: Build them out of solid lumber rather than fiberboard (spit and sawdust)? I make furniature as a hobby and MDF, etc is for shop jigs, not furniture.
What crossover can I buy rather than build? I am not that great at following electronics schematics.Otherwise I am VERY handy (Change my own timing belt, build Greene Bros. furniture handy)

Please be gentle.

 

[Cal Weldon]

I would think you could start with plywood and bond solid wood to it. Best of both worlds.

 

[MJL21193]

Can I: Build them out of solid lumber rather than fiberboard (spit and sawdust)? I make furniature as a hobby and MDF, etc is for shop jigs, not furniture.

Hi,
As you have some experience with hobby furniture building, you will be aware of solid woods tendency to expand and (mostly, initially) to contract. This poses a problem of cross-grain joints and unequal rates of movement.
If you can overcome this problem, then you will have no trouble building with solid wood.

Good luck.

 

[Lewis Moon]

Cross grain joints would probably only be an issue on the top and bottom, as the grain will go in the same direction on all of the side, front and back pieces. I also live in Arizona and these will reside indoors (air conditioned) with very little change in moisture. Also, using dewaxed shellac for the first two coats pops the grain as well as seals the wood well. I'm thinking of using rift sawn or quartersawn lumber so movememt should be minimal. Will the sonic quality be OK? I know they take great pains to select the wood for headphones.

 

[dnewma04]

I don't personally know any woodworkers good enough to pull off solid wood speakers, and I know a couple of people who have done cabinet work for a number of decades. If you can pull it off, my hats off to you, but I would suggest sawdust, spit, and some veneer. Or possibly some plywood as an alternative.

 

[Lewis Moon]

I wonder why that would be? It's really not rocket science and I have a number of pieces residing in my home and the homes of others, and have had no problems with any. A solid wood box, the dimensions required by a given plan would be relatively easy to build with dovetail, box or half lap joints. I'll probably use variable width box joints like Darrell Peart (see detail here: ) which I have done on several projects including a box that resides on a unheated porch in Indiana.
Would it be the acoustics afforded by solid wood?...because the material is quite forgiving and the techniques long established.

 

[MJL21193]

I wonder why that would be? It's really not rocket science

Hi Lewis,
No, it's basic wood joinery. It one of the big no-no's in wood joinery in fact.
If you have a stable hardwood, maybe quarter sawn oak, and you manage to get it down to equilibrium moisture content (and know it's at EMC) for the location it's going to be, then you will minimize the movement to the point where it may not be a problem. This has you "acclimating" the wood, similar to how a wood floor is laid after the material has been sitting in the room it will be installed in for a couple of weeks.

Doing a good job of sealing the box inside and out to slow down any moisture migration from exposure to a different environment and/or different humidity levels will go a long way.

A way of getting around the edge grain problem is to do the side, top and bottom with solid (grain parallel to the front, running continuous around the box) and use plywood or MDF for the front and back. Just veneer these to match. This will eliminate the movement problem and you can make strong glued joints.
This is the only way that I'd consider making such a box.

As for the sonic quality of solid - I know that proper box construction (bracing, joinery) will negate the differences. Solid wood, especially hardwood, has extreme stiffness along its grain - better than any wood based sheet goods. This is a good thing as you can concentrate bracing across the grain. Here again, you'll need to pay attention to cross grain joints if using a continuous type brace (shelf).

I hope it works out for you.

 

[MJL21193]

I'll probably use variable width box joints like Darrell Peart (see detail here: )

Sorry, i didn't see that link before.
This piece of furniture is an example of a builder who knows how to work with wood. The top uses breadboard ends - designed to accommodate the solid wood tops seasonal expansion/contraction. This is a technique that should not be used in a speaker box, as it will be a source of noise - either vibrational noise or air escape noise.
His solid panels in the doors and cabinet sides will be the same way - not rigidly glued in to allow for movement. Same deal here - not usable for a speaker.
Everywhere the builder has used correct joinery to ensure the seasonal movement of the wood doesn't undo the good work he has done. The drawers use dovetail or box joints and have the grain parallel around the box - this poses no cross grain issues. If the bottom of the drawers are solid, they are fitted the same way as the other panels - free to move in a dado. Stiles and rails are joined with mortise and tenon joints that are pinned - solidly at the outside of the joint and slotted at the inside. This lets the rails expand and contract freely across their grain.

Fine looking piece of furniture.
It's not a speaker though.

 

[Lewis Moon]

I plan on using the variable length box joints on all edges. I calculated wood movement to be fairly minimal (6-8/100ths) on the one axis where the grain direction does not match (the shortest axis). If the joint is fastened in the middle, that means about 3-4 100ths at each end, or about a millimeter. That could be easily fastened using a screw countersunk on both the top and bottom of the board (think hourglass). This would allow it to move far more than a millimeter. I have a quartersawn white oak footstool I built for my wife using this method and I just flipped it over to inspect the joints and the varnish isn't even cracked at the joint on a longer axis where the grain doesn't match after 8 years. Not a lot of movement at all.
I always put the first few coats of shellac on my pieces prior to assembly and then finish the piece as a unit. This assures that all surfaces are finished and sealed (and really cuts down on glue stains where glue is used). I also always sticker my wood for a couple of weeks prior to building.

Thanks for your attention to this.

 

[MJL21193]

I plan on using the variable length box joints on all edges. I calculated wood movement to be fairly minimal (6-8/100ths) on the one axis where the grain direction does not match (the shortest axis).
Thanks for your attention to this.

If the panels are kept narrow there is a greater chance for success.
If you do make a joint that allows movement, using silicone caulking on the inside corner of the joint will not impede movement and stop any air from escape through the seem.

Good luck and keep us posted on the progress and results. The solid wood topic has been talked about a few times here. I have done my part to discourage its use by the uninitiated, but you seem to have a good understanding of the challenge and the ways to meet it.

 

[AMV8]

Lewis Moon

You should be ok with real wood cabinets. My father was a cabinet maker and I have built two sets of cabinets using solid wood. I used oak for one set and mahogany for the other set. Both made of old table tops that I had.

I used a strong boat glue on the joints ( It seeps into the wood )and then ran glue along all the inner edges of the joints to seal them.

I set the back panel inside the sides with a 1/2 inch rebate for extra strength. I braced the sides and back and also added cross bracing between the sides and back and front. I stained the outside to the colour I wanted and then used danish oil.

I also has the use of a rebator so I let the speakers into the front panel so that they were flush with the front.

I hope you enjoy building and listening to your speakers.

If you get stuck on cross overs give me an e mail or try wimslow audio who will help you out.

Don

 

[sreten]

OK, lets get this out of the way first....I'm a complete N00B. I've been listening to Jazz, freakfolk etc on good to great (Grado/Alessandro) headphones for a while and I realized that the old Bose 301 bookshelf speakers (clean the coffee of your keyboard) weren't cutting it....at all.
I want to build a set of speakers because...I spent all my dosh on my (multiple) headphones. I was thinking about the Lyra TMW over at Speakerbuilder.net... Other suggestions?
Specifics: The room is about 15 X 23 with nine ft. ceilings, I like detail a LOT and the speakers need to have a fairly small footprint and basically be pieces of furniature.
Can I: Build them out of solid lumber rather than fiberboard (spit and sawdust)? I make furniature as a hobby and MDF, etc is for shop jigs, not furniture.
What crossover can I buy rather than build? I am not that great at following electronics schematics.Otherwise I am VERY handy (Change my own timing belt, build Greene Bros. furniture handy)

Please be gentle.

Hi,

The Lyra was a good design for its time and driver availability,
it still not a bad choice as long as you do follow the crossover.

The article in fact goes to great pains to show what will happen
if you simply use the parts express off the shelf croosovers.

http://www.speakerbuilder.net/web_files/Projects/Lyra/lyramain.htm

An externally hosted image should be here but it was not working when we last tested it.

However a more up to date and better design and smaller footprint :
http://www.partsexpress.com/projectshowcase/indexn.cfm?project=zdt35

You must build the crossover as shown, if you cannot get
someone else to do it / cross check your work and layout.

also see : http://www.zaphaudio.com/ZDT3.5.html

I would do some research on the use of solid wood in speakers,
noting that copying something like Sonus Fabers is a good idea :

An externally hosted image should be here but it was not working when we last tested it.

This uses a combination of real wood curved staves and MDF.

/sreten.

 

[Lewis Moon]

I thought about using the silicone too. Being that this might be a ported cabinet (I might switch to the Dayton 3) how much of an issue would this be?

 

[MJL21193]

I thought about using the silicone too. Being that this might be a ported cabinet (I might switch to the Dayton 3) how much of an issue would this be?

Hi Lewis,
You will still want to make sure that the rest of the cab is as air-tight as possible. Even if the box is ported, some air will escape through an open seam, and cause noise.
I prefer to make sure that all of my joints are glued tight, and 100% leak free, but then I don't use solid wood to build.
Maybe someday.

 

[Drew Eckhardt]

Sorry, i didn't see that link before.
This piece of furniture is an example of a builder who knows how to work with wood. The top uses breadboard ends - designed to accommodate the solid wood tops seasonal expansion/contraction. This is a technique that should not be used in a speaker box, as it will be a source of noise - either vibrational noise or air escape noise.

Dados can be cut a few mils undersize or the rabbet which goes into them a few mils over for a nice interference fit.

Stiff (Oak, Douglas Fir, etc) soild lumber braces build measurably stiffer cabinets than sheet good shelf braces.

I suspect you could make cabinets sufficiently air-tight without using glue or metal fasteners. Most cabinets aren't air tight, because otherwise they'd get static driver displacement changes as the air heats up inside. The visible gap on phase-plugged drivers works fine.

Join the panels with sliding dovetails. The front, sides, and back are built with the dovetails along the edge grain and join together with sliding dove tails. The top and bottom get rabbets which fit in dadoes in the front and sides. On the back they get an L-shaped extension machined in the wood or joined with a sliding dove-tail that fits a matching rabbet in the back panel.

I like the idea of a flush piece of dove tail from side to side through the top and bottom which locks it in place because it would let you knock the cabinets down without tools (or just a mallet to tap it out).

Use sliding dove-tails with a slight interference fit for the braces inside.

It's a fun thought experiment. In practice it seems like you want to use solid wood where it makes a visual or structural difference you can't get from sheet goods. Mitered picture framed veneered panels look nice. Wave guides turned from solid wood look nice. You can glue up with cleats, inlay solid wood at the corners, and put whatever edge on there you want. I want to replace my Pluto plastic pipe midrange enclosures with hardwood tubes or cones assembled with birdsmouth joints and turned on a lathe.

 

[Drew Eckhardt]

Picture-framing work in progress

Here's a solid wood edging example from my current project, where I wanted to play with solid wood and learn router joinery. I lapped the plywood and edge to keep everything aligned when it gets glued together and to make everything air tight even if the plywood is a little undersized. The feet pieces are joined with lock-miters because I wanted to learn how to make the joint.

I have horrid tear-out on two of the cross-grain plywood cuts thanks to bad technique (scoring in the right place fixes the problem) and using Home Despot birch with .010" face veneers versus .050" for the decent Baltic birch I've cut for the top panels.

The worst (not scored) is inside where it won't be visible; the other (score mis-located) is on the bottom so I'm going to igore it so I can get on and finish the project.