Here is a tutorial of how to build a speaker cabinet replica of the famous Marshall 1960a 4×12. I made a few mistakes, and had to do a few things multiple times. However, I think I can help someone else out there who’s looking to replicate this type of cabinet by showing you where I made mistakes and misjudgments. You should be able to build this much quicker and more accurate than I did, simply by learning from my mistakes. The post is long, so I broke it up into several pages, and added pictures throughout. I’ve also linked to some of the supplies needed for this build that you can order from amazon.
I don’t have a fancy shop or an elaborate workspace, as you’ll see in the photos, so when i started thinking about how to build a Marshall speaker cabinet, i figured I’d use only the equipment I had on hand. If I can turn something out this good using patio furniture as a workbench, I think anyone with a bit of know-how and some persistence can do the same or better.
There is one set of “plans” out on the web for this cabinet, but you can probably find others if you google how to build a Marshall speaker cabinet They are readily available, but they are little more than a CAD style drawing with dimensions. There is little instruction or help in the assembly process, so that’s the value I’m bringing here. Read my narrative on how this was assembled, and avoid the pitfalls that I fell into, and you should have a nice new cabinet in no time!
The Plans and the Supplies for how to build a replica Marshall speaker cabinet
I started with these plans from 18Watt.com and put together my shopping list (link coming soon). I’m not sure if someone at 18Watt actually drew the DIY Marshall 1960a CAD plan or if it was just hosted there. I couldn’t find any authorship to attribute them to. Even though it’s not really a plan for how to build it, it gives you most of the important dimensions to get going. Without this document, I would have been lost.
The first thing you’ll notice is the call for 5/8″ Baltic Birch. This is something that your local Lowe’s or Home Depot probably doesn’t carry. You’ll have to go to a lumber yard or a cabinet making supply outfit to find Baltic Birch. I searched around and only found a couple of places that carried it locally, and they weren’t interested in cutting it for me to fit the trunk of my SUV, so I substituted Oak from Home Depot, and made two big cuts in the store: enough to transport it home in the car.
I’ve played on this stack from Marshall, made out of Baltic Birch, as well as this one, and the tone, to me, is virtually identical. The big advantages of a void-free plywood like Baltic Birch is that each ply is solid Birch, and will result in better edges, miters, dovetails, etc. as well as superior screw holding capability. Since I knew I was covering this in Tolex, and using a quality wood glue on all my joints, I wasn’t concerned, and opted for the Oak.
Cut the Back Panel
My first cut was to cut out the large back panel of the cabinet. This is a simple cut, and I relied on the two square edges I had from the new piece of plywood to make it as accurate as possible. The dimensions from the pdf are 28-3/8 w x 27-7/8 h. (I did have to trim the height about 1/8th of an inch, down the road to accommodate the thickness of the tolex, and to not have a back panel that needed a pry bar to remove.)
Then, I measured and cut the space for the speaker jack with a jigsaw. I opted for a stereo/mono switchable jack, rather than an exact replica of the Marshall1960a, which would have been a single 1/4″ input. The hole in the back panel is centered and raised 4″ off the bottom. Next, I did a dry fit with the jack itself. It was snug and would be nice and tight once the Tolex was wrapped. I then removed the speaker input jack from the hole I just cut.
Cut the Sides
Okay, now we build the sides. The drawings detail these measurements perfectly. The angle of the cabinet for the top two speakers is 11 degrees. I suspect, the angle is where the “a” comes from in the DIY Marshall 1960a model number. I traced the first one, and cut the second one to the exact same measurements. This way, in case my angle was off, at least both panels would be off by the same dimensions.
I cut the bottom and the top panels directly from the dimensions on the drawing. It’s important to make a decision before you cut these how you wish to join the corners. If you plan on a dovetail joint, adjust the measurements accordingly, taking half the width of your plywood out of the length measurement. I simply used a butt joint and laid the top flush, in between the two side panels. This seemed to be the most logical joint based on the measurements. On the bottom, use the same method. I cut the bottom panel to sit within the the two side panels.
Assemble the Frame
I assembled and squared all the pieces to the outer frame, glued, and screwed each section to the other. The next part was to outline where the inner stops would be. These are 1×1 strips that attach on the inside of the frame to 1) stop the back panel from coming in too far, and 2) stop the speaker panels from collapsing into the body. I used 1×1 pine strips for this purpose and they worked great. My only problem was that I didn’t think through the final assembly while building.
Once I had all four of the panels cut (top, bottom, 2 sides) I measured and drilled pilot holes in all the joints. Do not skip this step. When using plywood, and screwing into the sides of a panel, it is very easy to split the panels. Do yourself a favor and drill pilot holes first. These #8 1-3/4″ wood screws worked great with a good wood glue. I got very tight bonds, too tight in some cases (we’ll discuss later).
Add the Inner Lip
Mark a line 3/4″ all the way around the inside of the frame. and mount the strips inside of that line. I did this on the front and the back of the frame, assuming that the speaker panel would be assembled from the front. But, as you’ll see later, it’s impossible to tolex the frame and add the speakers from the front. I found this out the hard way, and had already glued and screwed my strips on the front frame. I had to unscrew, then pry them off, fill with wood filler, and restart. The front does need these strips, but they are flush with the front all the way around to allow for the recessed speaker frame.
So, after a key mistake and a recovery I had a frame and the inner strips built, along with a flush-fitting back panel. I then cut the holes for the handles. This was a straight-forward process that was easy and mistake free! I used the measurements from the drawing which aligned the holes perfectly. It also helps to lay your handles on the marks before you cut, just in case you accidentally purchased handles that are a different size than the drawing specs. I lucked out, as mine were exact replicas of the 1960a handles.