Making Your Amp YOURS (D.I.Y. Part 1)

28 Feb Making Your Amp YOURS (D.I.Y. Part 1)

So if some of you out there are anything like me you customize or fix things to make them YOURS. Here I’ll attempt to show you how to build your own amp/speaker cabinet.  This will be part 1 of 2. The second part will deal with the covering (tolex) of the box. Keep in mind, also, that this is just my way of doing things. It’s not the only way. This will be a to the basics article.

Cab/Headbox dimensions are up to you. For the head I just copied the Marshall one that I was replacing.

This started out for me when I saw, for the first time, a Marshall special edition orange covered head and cabinet online. Soon I started on my own tone quest and started buying selling and trading gear to find my “tone” and look. It was only after I stumbled upon a dude named SoloDallas on the YTube, while trying to find a tutorial for ” Gone Shootin’ “, that I realized that tube amps were the way to go for meaty, crunchy raw power sound and tone. Naturally, like most of us, I don’t have money to throw around so I got innovative.

Being a carpenter it came easy for me to build my own boxes. So, the speaker cab featured below is of my own design. It is loosely similar to the Marshall 1936 cab. But I was able to slowly save and purchase all of the pieces until I could build the whole thing. (there are no build pics of the speaker cab. sadly after I started writing this I have come to find out that the flash drive they were on got SMASHED to bits!! 🙁 ).  I soon, also learned from Fil, about a guy named David Bray. (he did the mods to Fil’s 1987x head). Here in the US tax returns are a great thing. They allowed me to purchase a 1987x and send it to David for the now dubbed “SoloDallas Mod.” When I received the head from David his work was awesome but the head box was crap. (In NO WAY due to David’s work.) Finger joints separating, tolex tearing, dents, dings you name it. So what better way to fix this than to make a new box to fit the new cab.

But enough of my rambling let’s get to it.

(Just a small warning before I get to the pics and so fourth: You will need at least some background in carpentry to do alot of this work!!! If you don’t have the tools already the cost vs. benefit is not worth it. )

For Speaker cabinet building solid pine plank or 3/4′” birch select 11 ply. plywood are the two main choices for construction. In this case I already had some birch ply from another project. I actually prefer ply over solid wood because there is less chance of warpage due to grain pattern. For the head cab I used 1/2″ select Birch ply simply because that’s what Marshall used to build the original.

First is to make the simple outer box. After temp brad nails are in place next is to brad nail the corner gussets in.

(Make sure to glue ALL joints. I use Titebond II)

After the glue dries, drill the holes in the corner joints for the dowel connectors. I prefer dowels because it is nearly impossible to separate the joint after drying. (corner joints can also be done with dovetail or finger joints) Also drill through the sides into the corner gussets. The general rule I use for doweling like this is go 1/4″ smaller than the plywood that you’re going in to.

Next is to insert the dowels. You can either buy pre-cut dowels at a store or buy a long dowel and cut your own custom lengths. Be sure before insertion, of the dowels, to thoroughly coat them in wood glue. These are the backbone of the box stability.

The next step would be to cut off the dowels after glue has had time to dry. I use a Japanese style pull saw. (very clean smooth cut)

After doweling comes routing.

Marshall regularly uses a 1/2″ or 3/4″ round-over bit for their cornering. (3/4″ in this case) Make sure to do the 4 corners before the face or the outer corner points will not turn out right. Do not rout the rear of the box. Just relieve these corners and edges with some 80grit sandpaper.

Note that around the face there is a temporary 2ndlayer around the inside. This is there for backing the router bit bearing.

This is what the corners should look like after routing and the temp 2nd layer is removed

Note the backing strips for the front and rear panels. These will need to be set back far enough so that the piping in the face panel sits flush with outer box once everything is finally assembled.

Now is the rough cutting of the front and rear panels. The outer dimensions of insert panels like these (the same would apply to a speaker cabinet grill) should measure about 1/4″ smaller than the hole they will fit into. This allows room for tolex and piping to properly fit in the finish product.

The same applies to this panel as with the box. You must put on a backing strip for the router bit for a 3/4″ round-over. For the rear panel, the edges only need to have the sharpness relieved with some 80grit sandpaper.

If you’re doing a Head or cabinet with the 1/8″ beading I recommend clamping a guide/jig in place. This will make sure that your channels are perfectly strait. This channel needs to be 3/32″ deep and 1/8″ wide. Although, as you can see on the face panel, when you use the wrong mark to set the strait edge with your router will follow and you end up with a strip of bondo through the face panel. (good thing nobody will ever see it right????)  🙂

As for the placing of the handles, chassis holes, foot holes and so on, this I leave up to you to carefully measure and determine. I have no idea if placement is the same for even an original 1987 vs. a 1987x reissue much less the dimentions for all of the othe varoius Marshalls alone out there. This is also the case with the beading channels. I actually moved these ones from the stock location simply for my own liking.

That’s it for part 1. If there is any ?’s feel free to comment or use the private messenger. Below are a few pics of the finished speaker cab to try to show some of the building techniques.

The Baffle was made with 1/2″ ply for the surround. Center bar and emblem backing plate are 1/4″ ply.

Speaker panel is 1/2″ ply. The rest of the box is 3/4″ ply. See the Velcro pads in the corners and center? These are for the baffle attachment.

(notice the front edge of the cab is double thick so the speaker panel nails on from the back)

This is the side handle cut out. These vary by the type used. Mine (unfortunately) are the Marshall plastic ones.

One day I’ll switch to metal.

As you see I used the individual foot cups. Easy to mount for whatever head size you have. Only a paddle bit is

needed for the countersink hole. If you’re going to use the “skid trays” you will need to carefully use a router with a strait bit for the relief.

Here’s how I stiffened the corners. Integrated the stiffeners into the rear panel backer. (again… when installing the backing strips make sure to account for any tolex or piping thickness so your panel will not stick out!!!)

Full cab rear view for construction clarity. This may not be necessary, but I caulk all of the interior corners of speaker boxes to help eliminate rattles and sound bleed.

I chose urethane locking casters for a bit of a padded ride and smooth operation.

So these little handy parts are for mounting the speakers. Note the spikes that dig into the wood so they’ll stay when the speakers are removed . These are available at any hardware store with a GOOD hardware section.

I chose for a 3 piece rear panel with a removeable center. My only reason is so I have the storage for cords and ect… when I’m transporting my gear.

(notice the wiring jack. Two out side jacks for single speaker or used together for stereo. 4ohm in stereo with the 8ohm speakers. Center jack is both speakers wired in series for a 16ohm load.)

Here’s the wiring for the jack-plate above. (Note the un-sleeved wire connecting the tip lugs of the left & center jacks)

Again if you have any questions fell free to ask.

Thanx.