Speaker Cabinet Joinery

[tagger]

What choice of cabinet joinery are you speaker builders using? Do you vary your method depending on how they will be finished (paint, clear finish, veneer, etc)? I'm getting ready to build a subwoofer cabinet out of maple plywood, and I haven't decided whether to use simple butt joints with cleats or a more robust joint, such as rabbet or a lock miter. This cabinet must also bear the weight of a small child who will inevitably be climbing and standing on top of it often!

[coolhandjjl]

I build cabs for pro use, so this would hold true for anything. I use 1/2" Baltic Birch with a simpe butt joint. Baltic Birch is used as it is one of the more void free plywoods. With properly engineered internal bracing, 1/2" plywood is more than adequate, but I do feel vibrations on the cab. For home use, that may be problematic if it is used as a coffee table or similar. You can certainly use 3/4" plywood if you want. The key here is to make sure the plywood is rated as void free. Don't get 12 layer plywood with paper thin outer veneer either.

I use Loctite PL Premium urethane adhesive along the joint with a fillet along the inside of the cab. No need for biscuits, dados, rabbets, dowels, cleats or screws, it is plenty strong as is used at concert level SPL's. PL Premium is used because it slowly creeps into the joint as it cures, sealing any gaps from potential air leaks. However, cleats installed ahead of time, or shallow rabbets can be useful for positioning each panel so the plywood with its wet glue joint doesn't slide around while being clamped

My cabs' side and rear panels get covered with Tolex, whether it's a vintage Fender Tweed, or a basic leather-like texture Tolex. I finish my motor boards with shellac right over the birch plywood, or I dye the wood first depending on the style, then use shellac. All joints need to be masked so squeezed out glue does not stain the wood where you would see the joint when finished. You may want finish with some edge banding over the exposed plywood edges for cosmetic reasons, so plan ahead and adjust the size of your panels at those joints to allow for the thickness of the edge band. Or veneer the entire finished cabinet and you do not have to be so vigilant regarding little messes along the joints as you glue.

There is lots of discussion on alternative void free plywoods and use of PL Premium here: http://greenboy.us/forum/

[Guest " "]

early heritage speakers had internal bracing along with butt joints so that the fronts and backs could be screwed or nailed in. Later they moved to mitered cuts with dado cut groves on tops and sides for the fronts and back. When ever I use miterd cuts, I still internall brace. For painted or covered applications, butt joints are fine. Veenered applications work better with mitered joints.

[coolhandjjl]

I would think mitered cuts would be the hallmark of a master woodworker. Not sure what the OP has for experience.

[tagger]

I'm a hobbyist woodworker. I've done miter cuts on my table saw, but I was interested in trying a lock miter joint. Or is that overkill?

[coolhandjjl]

I've seen guys dovetail plywood. Just because they could. It's all up to you. We all have our own quirks and obsessions when it comes to craftsmanship.