Plywood for Cabs?

Does plywood just plain suck for cabs?

I decided to build a cab for my latest amp, which is a 4-6BM8 job based on the 5F6A. I recently built a Mojo kit for somebody, and he said Mojo told him the cab was Baltic birch plywood. I figured that was good enough for me, and I thought plywood would be unlikely to warp.

I got myself a sheet of the best plywood Home Depot had, and I ran it through the table saw. I taped the edges when I cut, and I used an expensive blade, but I still got a crappy result. I ran it through the table router to clean it up, and it still looked bad.

I can fix it with wood filler, and the damage will be under vinyl, but I feel like I should have picked a nice spruce board instead.

Home Depot's 'best' is not remotely close to voidless baltic birch.

Home Depot's 'best' is either construction grade or construction grade with a sanded veneer.

If you are going to go with what's available at the big box stores you are probably better of with pine or select whiteboard.

I got myself a sheet of the best plywood Home Depot had, and I ran it through the table saw. I taped the edges when I cut, and I used an expensive blade, but I still got a crappy result. I ran it through the table router to clean it up, and it still looked bad.


That Home Depot stuff has splinters you can use to kill vampires.

Near as I can tell it's Russian veneer assembled in China. You might want to look up an industrial lumber supplier and buy a sheet of real Baltic birch but be warned, it ain't cheap.

The Home Depot stuff has wavy plies in its core with voids.

The Russian stuff has a nice uniform core, no voids.




I can fix it with wood filler, and the damage will be under vinyl, but I feel like I should have picked a nice spruce board instead.

Pine. Way I figure it most Fender amps came in "pine" cabinets from 1950 through 1980 and beyond.

I mentioned spruce because that's what HD stocks. But how bad can it be? It makes great guitar tops.

This amp is just a head, so I'm not worried about voids, but if I build a combo, I guess I'll have to get real wood.

Can Baltic birch be routed without flying apart? I used the router to put a radius on the wood.

Find a local lumber yard and get a sheet of Baltic Birch. Pretty pricey, but exactly what you want.

Hard enough finding a decent 2x4 at HD let alone decent ply.

...Can Baltic birch be routed without flying apart? I used the router to put a radius on the wood.

If it is high ply voidless then yes it routes just fine.

But for a head? Who cares what it's made of, use the cheapest straight lumber you can find.

Definitely voidless! I've used them both ... same exact builds, just different wood. Voidless Birch is what it takes.

Here's something plywood that's very cool:

http://www.vintage47amps.com/files/index.php?id=14

I had a customer, who built kitchen cabinets build a Twin cab for me. He used the pitiful local ponderosa pine that can be cut now. (The forest service likes to set most of it on fire, like the one we have going now). I think one side is at least 3 pieces, but it really is strong. Thinking I might go that route for the next speaker cab I build. I have a bisquit tool, just need to get someone to run the boards through a planer, and joiner.

Another option might be the laminated boards (might be pine) that the big box stores sell. I may have seen it in the shelving section. A bunch of 1 or 2x boards laminated together to make a 12" or wider x 3/4" board. They had them in different lengths. They were light weight with no warping or splitting and priced real reasonable.

Another option might be the laminated boards (might be pine) that the big box stores sell. I may have seen it in the shelving section. A bunch of 1 or 2x boards laminated together to make a 12" or wider x 3/4" board. They had them in different lengths. They were light weight with no warping or splitting and priced real reasonable.

I was considering those as well for a cabinet. I believe they are economy grade butcher block type boards. I used them in my garage for countertops. They are not the most durbable, but look really nice with a clear sealer applied.

Another option might be the laminated boards (might be pine) that the big box stores sell. I may have seen it in the shelving section. A bunch of 1 or 2x boards laminated together to make a 12" or wider x 3/4" board. They had them in different lengths. They were light weight with no warping or splitting and priced real reasonable.

I was considering those as well for a cabinet. I believe they are economy grade butcher block type boards. I used them in my garage for countertops. They are not the most durbable, but look really nice with a clear sealer applied.

"Number Two" pine is cheap.

What is your labor worth?

Is your labor so cheap you can afford to waste it on cheap materials?

I believe in doin' it once and gettin' it right the first time. If it ain't right the first time it will be a lot closer the second time.


Hint: I'm payin' around $5.00 for a 6' 1"x10" which works out to $10.00 for a twelve footer. It's number two which means it has knots. I can easily cut 16"-24" clear between knots. Knots go in an old grain bag for campfire wood, "clear" pine panels go into cabinets. Sometimes I'll leave a knot in but I try to avoid loose black knots. Knots shouldn't be on the edges, they'll cause problems later.

A knot can go anywhere in the control panel cutout because it gets (wait for it!) cut out. Just don't get tricky and cause problems for yourself.

I will never buy this crap plywood again. I'll just look for good spruce.

Today I finished roughing out the front of the cab. It will work, thanks to wood filler, but the plywood splinters pretty badly.

The reason that plywood is used so often by high-end speaker manufacturers is to avoid lumber that has resonant frequencies. Such makers also pay attention to things like Thiele-Small parameters.

Guitar speaker cabinets have traditionally been made without such considerations. They were originally built to size and strength without much thought given to the acoustical properties.

It came out looking pretty good, as long as you don't go over it with a microscope. I should really redo the ivory panel, but I like it.

I have to do the nameplate and faceplate now.