22 Sep

Resurrecting a Speaker Cabinet

I’ve had this empty guitar amplifier cabinet for a few years now. The amplifier chassis has been long gone, and the single 8” speaker that’s remaining is just too small and underpowered to handle any decent wattage. So it’s just been hanging around my shop, gathering dust. But, if you have a few, basic woodworking tools and a little bit of spare time, you can resurrect old amplifier cabinets and speakers, transforming them in to very usable and good sounding guitar accessories that you’ll actually use!

Two Speakers
I happened to have this spare high-power 12” Peavey Scorpion speaker lying around the shop. I’d always wanted to use this speaker in something cool, and this little cabinet would be the perfect host. Before you start cutting and modifying the cabinet though, make sure your new speaker will actually fit in the host cabinet. If you’re satisfied that it comfortably and securely mounts in the cabinet, then proceed onwards with the rest of the work.

Cab Taken Apart
Here’s the rear of the cabinet, with the baffle board and attached speaker removed. There are four machine bolts that the baffle board uses for mounting to the inside of the cabinet front. In order for our new 12” baffle board to fit flush against the interior of the front, we’ll have to remove these mounting bolts.

Bolt Cutting
Using a high speed rotary tool, carefully cut down the old baffle board’s mounting bolts as close as possible to the wood. Take care to not catch your cabinet on fire, as the rotary tool produces sparks and hot particulate matter when cutting metal parts. You may want to take a wet rag and lay it down on top of the wood surface surrounding the particular bolt you’ll be cutting off.

Baffle Board Layout
Using the rear vented cabinet panel, we can layout the exterior dimensions of the new baffle board we’ll be cutting. I’m using some furniture-grade 5-ply Birch plywood stock for the new board. Trace out the exterior dimensions of the rear panel on to the top of the plywood so you’ll be able to carefully cut along the lines using a saw with a fine tooth blade.

Exact Center
Trace two lines between opposing corners to form an “X” on the inside of the rectangular shape. Where the two lines of the “X” meet is the exact center of the rectangle, so mark this point for future reference.

Trace Cut Outs
Once you’ve cut the new baffle board out, place it inside the empty cabinet so we can trace the outlines of the front panel cutouts on to the face of the board. Depending upon the design and layout of these cutouts, you may want to mimic them with the new baffle board design, or go an entirely new route with a custom design for the cutouts on the front panel.

New Board Cut
Here’s the new baffle board, with the interior cutouts made, and all exterior edges sanded smooth. Continually check the fit of the board in place on the inside of the cabinet. You want the new baffle board to fit completely flush, with no gaps at all. The tighter the fit, the more resonant the cabinet becomes, and that’s a good thing!

Tack Grill Cloth
Before we cover the front speaker grill, spray paint the wood flat black. This will help the new grill cloth to look more uniform, and professional. I found this mesh screen that we’ll use for grill cloth in my kitchen drawer. It matches the plastic trim beading on the cutout edges perfectly. Whatever material you decide to use for a grill cloth, it needs to be acoustically transparent, which means it won’t block any of the frequencies and sound coming from the speaker cone. It also serves to protect the fragile paper cone from any accidental damage, and it looks cool! Measure the cutout openings, and you can tack on the new grill material covering pretty easily.

New Speaker
Place the new speaker in position on the new baffle board, positioning the four mounting holes so that they are placed directly over the baffle board’s interior wood surface. We’ll use some heavy duty wood screws to attach this speaker, along with some washers to help prevent rattling while being pounded by a loud tube amp! Torque the four wood attachment screws down, so that even pressure is applied on all four sides. This will help prevent warping of the speaker frame, which can cause a speaker voice coil to melt quickly due to interior friction.

Loaded Cabinet Rear Finished Cab
Here’s the completed new baffle board, installed with grill covering material in place. This has a very nice, vintage-vibe appearance that houses a very powerful 12” speaker in an incredibly compact package. Great for taking along on impromptu club gigs. It’s also a great companion to the new generation of small, compact tube amplifiers from makers such as Blackheart, Egnater, VOX, Burris and others. This speaker cabinet allows these miniature tube amps to project a lot of power and tone capability in a small physical size.

Until next time, keep on rockin’!

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