Monthly Archives: December 2014

DIY Marshall 1960a 4×12 Speaker Cabinet Project

Posted on by
DIY Marshall 1960a

My finished 4X12 1960a replica cabinet with my old Valvestate 8100 head.

Here is an overview of the DIY Marshall 1960a speaker cabinet that I just completed. I took lots of pictures, (full photo gallery here) 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 3 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.  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.  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

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.)

I then 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.  I centered the hole in the back panel, and raised it 4″ off the bottom, then 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.

IMG_69965494564707ef6.JPG

Hole cut in the back panel, centered, and the bottom cut 4″ off the bottom of the panel.

IMG_6997549456473c60f.JPG

Dry fit with the actual speaker jack in place.  This shouldn’t be too tight, as you’ll have to leave some room for the Tolex before final install.

Cut the Sides and Assemble the Frame

Okay, now on to the sides of the cabinet.  These were dimensioned exactly in the drawings, so no trouble here.  The angle of the cabinet for the top two speakers leans back at 11 degrees.  I suspect, the angle is where the “a” comes from in the DIY Marshall 1960a model number.  This angle was a simple mark with a protractor, then extend the line to the top of the side panel.  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.

IMG_690154945632e39a7.JPG

Side piece cut off of the square side of the plywood sheet. Cut this, trace a second one, and cut it, so your setback angles match exactly.

IMG_691354945635702b6.JPG

Mark and drill pilot holes for all of your joints.

These are the screws I used. #8 1-3/4" woodworking screws.

These are the screws I used. #8 1-3/4″ woodworking screws.

I cut the bottom and the top panels directly from the dimensions on the drawing.  The top was 29 3/4″ x 10 11/16″ and the bottom was 29 3/4″ x 14″.  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, the same method was used.  I cut the bottom panel to sit within the the two side panels.  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.  I used these #8 1-3/4″ wood screws for my build, and they worked great with a good wood glue.  I got very tight bonds, too tight in some cases (we’ll discuss later).

I assembled and squared all the pieces to the outer frame, glued, and screwed each section to the other.  I now had somewhat of a frame.  The next part was to outline where the inner stops would be.  These are 1×1 strips that are secured 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.

I marked a line 3/4″ all the way around the inside of the frame. and mounted 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.  It has to be Tolexed, and the speaker frame slid in from behind.  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.

Rough frame of the cabinet.

Rough frame of the cabinet.

IMG_6928.JPG

Setback for inner 1×1 strips 3/4″ all the way around. (5/8″ + 1/8″ for width of tolex.)

IMG_69315494563d9337b.JPG

This is incorrect! These front strips should actually be flush with the front of the cabinet, and the rear  strips should only be added AFTER the speakers are installed from behind. (learn from my mistake)

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.

Create Space for the Handles

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

IMG_692354945637ce95f.JPG

Test fit of the back panel. There should be little to no resistance at this point, as you’ll have Tolex on both surfaces at the end.

IMG_6965549456435c90f.JPG

Simple rectangular cut for the cabinet handles.

IMG_696754945643c62fc.JPG

Dry fit of the handle in the newly cut hole.

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 made up of two pieces of plywood, joined together with a custom brace in the middle.  The first thing I did was cut the two main pieces.  Although they look similar in size, the bottom piece is slightly taller, as you can see in the dimensions on 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.

Once the holes are cut, comes the tricky part.  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, a 3/4″ x 1/2″ frame should be added on the front of the speaker assembly to hold the mesh off of the wood.

IMG_69355494563f2cb26.JPG

Speaker holes centered and marked with a compass for cutting.

IMG_69365494563f84f00.JPG

A dry fit of the pieces before the holes are cut and the brace is fitted.

 

IMG_6945549456400c22c.JPG

Drill a pilot hole near the inside of your circle and begin your cut with a jigsaw.

 

IMG_6947549456407b69e.JPG

My rig to cut the 11 degree angle into the 2″ x 26″ brace.

IMG_69505494564135751.JPG

After the brace was built, I screwed and glued using clamps to match the proper angle, and let dry.

IMG_696054945642c87b6.JPG

The last step is a frame all the way around the front. This too should be painted black.

 

 

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 most of this will ultimately be covered 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.

IMG_697654945644c538b.JPG

Spray painted speaker panels.

IMG_69755494564490dd9.JPG

Inside of the frame sprayed, just to be safe!

IMG_69565494564289661.JPG

Dry fit of the frame before the speaker mesh goes on.

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’re done with one side, stretch it taut across the frame and make sure the grid is fairly square on the front, and begin stapling on the other side the same way.  Then do sides 3 and 4 taut as well, making sure the whole time that you’re not stretching too much to distort the grid in the speaker mesh.  Once all four sides are done, you can slice the corners with a blade at a 45 degree angle outward, and 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.

IMG_698454945645c1c0c.JPG IMG_698554945646000a0.JPG IMG_6986549456463506d.JPG

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.

Speakers simply bolt on to the existing machine screws you added earlier.

Speakers simply bolt on to the existing machine screws you added earlier.

IMG_69805494564530999.JPG

filling screw holes and imperfections in the wood.

IMG_698254945645905e5.JPG

Go all the way around and fill every hole.

Tolex the Cabinet

Once your holes have all been patched, you can start the Tolex process.  This is a time consuming process, and I would recommend doing it in a dust free place with plenty of ventilation.  The cement is rather strong, and can make you lightheaded if you’re not properly ventilated.  I ordered 3 yards of this Tolex and it worked perfectly.

I started with the back panel, as it was the simplest of the pieces, and if I made a mistake, it wouldn’t be readily visible.  You’ll need about a quart of contact cement for this process.  Don’t use regular glue that will harden.  This is the contact cement I ordered, and it was very manageable.

The Tolex process is pretty simple.  Paint the cement on the canvas side of the tolex, and the wood you’ll attach it to.  Let both pieces sit for about 5-10 minutes until both sides are tacky.  Then apply evenly from one side to another pushing out air bubbles as you go.  I wrapped my tolex around the back panel by about 3 inches and then trimmed it to a 1 inch overlap.  I taped each side down until the cement dried, just to keep a tight bond.  On the corners, make one cut 45 degrees outward, then overlap the two flaps, and make another 45 degree cut through both pieces to give yourself a perfect seam as shown below.

IMG_7002549456476adbd.JPG IMG_700454945647c71c8.JPG IMG_700354945647985f3.JPG

After getting the hang of things on the back panel, you can move to the body of the cabinet.  I chose to do this with one seam on the bottom, and roll the whole cabinet in one big long piece of Tolex.  I started with the bottom, followed the instructions above, and then moved over to the side, the top, the second side, and then back to the original start, where I made one seam that is on the bottom panel.

Now I have all the panels Tolexed, but the sides and corners need to be glued.  This is a slow and tedious process that can only be done properly by being careful and deliberate.  The straight sides are easy, and not difficult, but the angle of the slant in the cabinet will naturally create a bubble at that point.  I had to slice across the bubble with a blade, and manually make a small seam there on the point of the cabinet angle.  It’s visible, but only when you look hard. (Even the real Marshall cabinets have this seam).

starting the Tolex process on the DIY Marshall 1960a

Cement both sides and let it get tacky before adhering.

IMG_7006549456483976c.JPG

Start with the bottom, about 1″ from the edge.

IMG_700954945648c55ea.JPG

As each panel gets glued, rotate the cabinet.

IMG_7011549456492d684.JPG

All four panels are glued now, and a single seam is on the bottom.

IMG_701054945648f2397.JPG

Your back corners will look like this.

IMG_7012549456495c18c.JPG

Cut a single 45 degree cut outward, to make two flaps.

IMG_7013549456498dd95.JPG

Overlap the two flaps, and then make one 45 degree cut from the corner inward through both pieces of Tolex.

IMG_701454945649be72f.JPG

You now have a perfectly matching seam.

IMG_701554945649edb39.JPG

Glue the seam and butt each piece up to the next perfectly.

IMG_70185494564a8b245.JPG

Your front seams will have an extra lip for the frame, and will require two angles in each cut.

IMG_70215494564aefb2e.JPG

One 45 degree angle, and a vertical will allow for a perfect seam on both the outer and inner frame.

IMG_70225494564b56034.JPG

At the angle in the cabinet, you’ll have to create a small seam with your blade and manually maneuver the Tolex to fit best here.

Install the Marshall 1960a White Piping

After some hard work, and heavy cement fumes, you should be ready for the piping.  I purchased 11 feet of this manufactured by Marshall.  It simply staples in from behind the front lip.  Staple all the way around, and create a single seam in one of the bottom corners.

starting the white piping on the DIY Marshall 1960a

Start in one corner, and staple every half inch or so all the way around.

DIY Marshall 1960a white piping corner application

Staple more frequently in the corner to get a good bend.

DIY Marshall 1960a white piping installation

Continue all the way around until your piping is complete.

Wire the Speakers

I didn’t take pictures of this part since everyone’s wiring setup might be different.  There are different methods based on the type of input jack(s) you choose, but the methods are easily found on the web.  One thing that makes assembly easier is using the slip on speaker connectors so that you can wire everything in the cabinet, then as you put the back on, just slip the two or four connectors on their posts and close her up.

I’m assuming you’ve wired your speakers in the frame they sit in currently.  Now we go ahead and slide that frame in the back of the cabinet, and flush with the front lip and white piping you just installed.  At this point, I added a 1×1 strip behind each panel as snug as I could get it to keep the speaker panel in place permanently. Go ahead and install your handles now, as they should slide in the holes and screw in easily.

Finishing Touches on the DIY Marshall 1960a

Next, connect your speaker wiring to your speaker jack, and screw on the back panel.  I used stainless screws and grommets to replicate the look that Marshall uses.  After the back plate is on, turn the cabinet over and screw in your casters or wheels, as well as the corner brackets.  Turn her back over, glue the 11″ Marshall logo on the speaker mesh for the final touch, and you’re done!

DIY Marshall 1960a back panel screw alignment

Double screws in each corner to prevent rattles.

DIY Marshall 1960a caster closeup

Closeup of the amp caster and corner piece.

DIY Marshall 1960a casters

Amp casters attached to each corner for easy transport.

DIY Marshall 1960a speaker input

Screw the stainless screws all the way around the back panel.

Finished DIY Marshall 1960a Cabinet

All finished, ready for testing.

DIY Marshall 1960a 4x12 speaker cabinet

Finished product live and in action!

Category: Wood Working