How to build a Marshall Speaker Cabinet REPLICA (1960a 4×12)

Create Space for the Handles

I cut both holes, and dry fit both handles before proceeding.

We’re now at the point of having a full frame, a back, and holes for the handles on each side.  Next is the speaker assembly.  This can get a bit tricky, but overall, will be hidden with the speaker mesh, so don’t worry TOO much about appearances at this point.

Build the Speaker Mount

The speaker assembly is two pieces of plywood, joined together with a brace in the middle.  The first step is to cut the main two pieces.  Although they look similar, the bottom piece is slightly taller, as you can see in the drawing.  After cutting the two pieces I sketched out the holes for the speakers.  Each speaker hole is 11″ in diameter, and the speakers will mount from behind the hole, not the reverse, as you would assume.  The drawings didn’t give specifications for location of the holes, so I simply centered mine  with about a 2.5″ gap in between the speakers horizontally.

Next, you have to cut a 2″ wide piece of plywood 26″ in length to brace the two pieces together.  You also have to cut this piece at an angle to match the angle of the lean of the top speaker assembly piece.  This should be 11 degrees.  Once you cut this piece and match up the angle, you can glue and screw it to the two plywood pieces with the speaker holes in it.  Use shorter screws here, but make sure you have a tight bond and good contact with all three pieces of wood, as this piece will be somewhat load-bearing in the final assembly.

Finally, add a 3/4″ x 1/2″ frame on the front of the speaker assembly to hold the mesh off of the wood.

Paint the Exposed Wood

Now, we have the full frame of our DIY Marshall 1960a, and the speaker brace built.  I then spray painted flat black onto the front of the speaker brace, and inside the lip of the cabinet frame.  Remember we’ll cover most of this ultimately with Tolex, but painting the whole thing black won’t hurt you, it will just cost you more time and money.  I only painted the areas that could possibly be visible after Tolexing.  With the dry fit of the speaker panels, you need to make sure there is at least a sixteenth of an inch clearance all the way around to accommodate the speaker mesh thickness.

After the paint dried, I laid the speakers on the holes, marked and drilled each hole for the mounting screws.  I drilled each hole the same width as the screws I used, so when I pushed them through they were snug, even without a nut on the other side.  This is important, as you screws will need to be in place before your mesh.

Installing the Speaker Mesh

You’ll need about a yard to a yard and a half.  Here is the type I ordered. Start with one side, staple at an angle every half inch or so all the way across.  Leave the corners open for now.  Once you’ve done one side, stretch it across the frame, and begin stapling the other side.  Then, do sides 3 and 4, making sure that you’re not stretching too much to distort the grid.  Once all four sides are done, you can slice the corners with a blade at a 45 degree angle outward. Then fold over, staple taut, and trim any excess.

This process looks difficult, but it’s not really.  It only took me about 30 minutes, and it looks very professional.

Installing the Speakers

Only after the mesh is finished, can you install the speakers.  This should be done on a flat surface, since the speakers are rather heavy, and you don’t want to put any unnecessary load on the brace you just built. Since the screws are already in place, you simply lay the speakers onto the holes, and add a lock washer and a nut on each screw.  This is time consuming, but make sure each one is tight, so you don’t have any rattles in the cabinet down the road.  This speaker assembly will be pretty heavy once all speakers are in, set this aside and on to the next step.

Rounding the Edges

So, your frame is more or less complete.  Now we have to do some beautification.  Start with a router, to make the roundover on each corner.  The drawings of the DIY Marshall 1960a called for a 1″ roundover, which I found out is an extremely hard-to-find bit for a handheld router.  I only found one online, and it was over $100 for the bit itself, so I used what I had instead, and settled for a 5/8″ roundover and a palm sander to finish it off.  Let the router do as much of the work as possible on all the edges (except the inner edges).  Then a palm or belt sander with a 60 or 80 grit paper will really smooth it out further.  I definitely don’t have the Marshall 1″ roundover, but you wouldn’t know it unless you were looking for it, so I’m fine with that compromise.

Last Minute Prep Before Tolex

After the roundover process, I used wood filler to fill each screw hole or chip in the plywood.  I let it dry, sanded it smooth and wiped it clean with a damp cloth, since the tolex was the next step, you need a clean surface for the cement to stick to.  The pictures below show what the cabinet looks like during the fill/sand process.