Step by Step - How to build a head cabinet.

[Prages]

This is copied from a thread I did on another message board. Excuse any references to dates or other board specific events.

Last Friday I picked up what I consider the deal of the year...a 1984 Marshall JCM 800 head...cost $381.60 after tax. The amp sounds amazing, but as you can see, the tolex has seen better days:



Also in the pic you can see my road tested Peavey 412 cab (loaded with Celestion G12T75s). The cab sounds great, but also shows some battle scars.

Well, I decided that I was going to recover the set, but rather than rip the original tolex off the Marshall, I've decided to build a new head cab, that way if I do decide to flip the amp, it'll still be all original.

I got a good start today. Building a head cab is really not too complicated if you have a table saw and a dado blade at your disposal.

I bought an 8 foot long, 10 inch wide, 3/4 inch thick piece of clear pine for the cab. I was going to do it in 13 ply baltic birch, but the solid pine was about 1/2 the price, so I went with it.

I measured the outside dimensions of the original head and cut my pine plank into the appropriate size pieces.



Now, I built a speaker cab about 2 or 3 years ago and made a finger joint jig. It's basically a piece of wood used as a backing block with a 'key' made of hardwood. The key has to be exactly the width of your dado blade, and has to be exactly as far away from the blade as the blade is wide. Then you screw the jig to the guide on your table saw. If you get this jig setup right, you can cut all your finger joints in about 5 or 10 minutes and they fit together perfectly.

The jig:


The jig in action:


I got a little ahead of myself and forgot to take a picture, so I went back and set the wood into the jig so you'd be able to see how you just move the piece of wood over to the new dado cut with each consecutive pass....ignore the fact that there are already three cuts past the blade.


You have to make sure that you have the cuts offset on the pieces that are being joined together. So on one side, you'll have a cut right on the edge of the wood, and on the piece that joins it, your cut will be the width of the blade into the wood. Here's all four outside pieces with the cuts.


Here's what they look like when you put them together.




Then, I applied the glue (I'm using Titebond yellow wood glue) and clamped it all together, making sure everything was square. I didn't have long enough clamps to clamp it lenthwise, but I did have a bunch of ratchet straps, which work perferctly for my purposes here.





Now I'm just waiting for the glue to dry overnight. Tomorrow I'll sand the joints flush and put a 1/2" roundover on them using a router. Then I'll glue in some stringers for the front and back faces of the cab.

Hopefully on Saturday I'll be able to cover it with burgundy tolex (the same thing I've already used on the cab (sorry no pics yet) and mount the chassis and hardware.

So far, I've spent more time typing out this thread than I have on working on the cabinet. Once you get the jig made, keep it for future projects. I've literally got about 20-30 minutes of work in this thing so far...tops.

[Prages]

After letting it dry overnight, I unclamped the cab and used a belt sander to sand all the joints flush and remove any excess dried glue.



Then I sanded all the edges to get everything completely flush. Here's what it looks like after it's sanded.





And one of my dogs, Cooper, inspecting his daddy's work:


Then I cut the front stringers from a piece of scrap from the original 8' plank that I ripped down to the right width. The scrap strip was perfect for the stringers and should be enough to do both the front and the back. Then I glued and clamped them to the cab. Now I'm once again waiting for the glue to dry. I'll probably let it dry until about 3 o'clock today, then unclamp it and do the back.





Hopefully the handle, feet and corners will come in today. If they do, I should be able to finish this sucker up tomorrow.

[Prages]

Well, my hardware didn't come in today, but that's alright, I'm pretty much done with everything except covering it and putting the hardware on...and I've got a gig tonight so I can't really do anything else tonight anyway.

I glued up the rear stringers this morning and took the clamps off about an hour ago. The only thing different between the rear and front is that I recessed the rear a little bit and didn't bring them all the way to the bottom of the cab, giving the amp guts room to slide in.

So, the next thing I did, which for some reason I forgot to take pics of, is put my router on a router table and use a 1/2" roundover bit to round the corners.

Then, I used a drill and forstner bit to drill the four corners of each of the three vents I'm putting on the top of the amp. I got the little inserts I'm using at Lowes...they are gutter caps or something. They were too long, so I ran them through the bandsaw to make them as thick as my wood. Then I painted them black since they were grey to begin with.



Then I took a jig saw and finished cutting the vents.



The vents are done, and you can see how the corners are rounded over in this pic.



I'm using a piece of 1/2" oak plywood for the face. I only used it because I could get a 1/2 sheet of it cheaper than I could get anything else. I also used 1/2" instead of 3/4" because I wanted the face to be recessed slightly. I cut some mounting brackets out of the unused piece of plywood and screwed them to the front stringers.



Then simply screwed the face plate on from the back.



And then I slid the amp itself into it's new home for the first time.






There are a couple of knobs missing, so I ordered a new set of knobs when I ordered my other hardware.

Tomorrow I'll get the new tolex on it. Then Monday, hopefully my parts will come in and I can have it completely finished.

I've probably got about 2 or 3 hours of work into it at this point. I couldn't be happier with the outcome.

[Prages]

I decided that I needed to glue a thin strip along the bottom face of the amp (The original Marshall cabinet also has this), so I ripped a 1/8" strip from a piece of pine and glued it on.



Then, I cut the grill that's going to cover the vent holes in the top of the cabinet and screwed into place.



I'm going to let that dry for a few hours before I can do anything else. I'm pretty sure my hardware is being shipped USPS, so it's possible that it'll get here today. Regardless, I should be able to get the thing covered today. :thu

[Prages]

Alright, I'm as finished as I can get without the feet, corners, knobs and piping.

Covering is probably my weakest link. I've only really done one or two things...two of them being the 412 cabinet and this head, so I'm no expert and the results aren't entirely perfect, but it doesn't look too bad.

I didn't actually use Tolex. I used some pleather type stuff from Walmart that was $3/yard. I got 4 yards of it and had enough to do the 412 and the head, with enough left over to do at least one more head (I'm thinking about building a head cab for my Classic 50 212). This stuff looks nice but is a lot less durable than tolex. I'm just going to have to be really careful not to rip it up. Luckily, I'm usually really careful with my stuff, so I don't really foresee a problem. Only time will tell though.

Anyway, you'll want a fairly large table or a clear patch of floor to do the covering. Since I've got 3 curious dogs, I decided the floor wasn't a good idea. I used the pool table.

First, I layed out the covering.


Then I just rolled the head end to end along the covering and cut about an inch or two longer than I thought I needed.


I cut the vinyl about 8" wider than my head cab so I'd have plenty to work with. Then I marked the back of the fabric 4 inches from the edge all the way down the length so I could make sure I was keeping the fabric square...you don't want to get it on crooked and only have 1/4" to staple at the end. So, just mark the fabric and make sure as you go the edge of the cab lines up with the marker on the fabric.


Then I actually started glueing. I used Duro brand All-Purpose Spray Adhesive and it seems to work really well. I also staple the fabric in places where it won't be seen. Anyway, start on a bottom corner. Spray both the cab and the fabric with the adhesive and pull the fabric up. The adhesive is pretty forgiving so if you get a wrinkle, you can pull it back off and try again. Little wrinkles can be worked out by just using your hand to smooth them out to the edge.


I haven't really perfected my cornering, but it's getting a little better.


Here you can see some staples.



I did all the back corners first thinking that I'd be a little better at them after 4 trial runs. Don't know if it helped or not. The good news is that I'm putting metal corners on it, so most of the little gaps will be covered by the corners.





Once I got back around to where I started, I used a straight edge and a razor blade to cut both pieces of fabric at the same time, then I sprayed the adhesive and stuck the pieces together. The seam came out pretty well. The white backing on this fabric is a bitch, but I don't think real tolex has that.



Here are some front corners.

[Prages]

Then I covered the face plate and put it on the cab.


The Marshall cab had a piece of metal on the bottom. I assume it's for shielding since the bottom of the chassis isn't covered. So, I put a piece of steel I bought at Lowes in there. I just screwed it to the bottom.


Then I mounted the amp itself into the chassis.

Now, remember the metal corners are going to cover up the little goofs in the corners.

So, here's the before and after:

















I still need to get something to use as a back grill. I was going to use the one off the old cabinet, but it's a little bit too big to fit into the new cabinet, and I don't want to cut on it.

I'll take more pics whenever I get the hardware.

I also have a Marshall emblem on it's way to me.

[Prages]

I finally got all the rest of my parts. I didn't take pics of each step at the end, but basically all that was left was putting on the feet, handle, logo, knobs, piping and corners. The gold piping didn't show up too well in the pics, but there is gold piping around the face plate. Here it is with my 412 which I covered in the same material.

[Prages]

A year later, I sold the Marshall amp and built a new face plate for the homemade cabinet and mounted the guts of my Peavey Classic 50 in the cab.

[hobo]

COOL!!!

[Mark Wein]

That's awesome!

Thanks for posting that. I have my old Marshal 4x12 and a bolt of Tolex that I've been afraid to get started on for about 5 years, now....your post is inspiring me to give it a try...

[Prages]

I think with real tolex, you'd probably find it a little easier.

Also, there are better ways of doing the corners. You definitely don't want to use a steak knife like I did.

I think a razor blade is the ticket.

If you cut your tolex so you can fold it at the corners without wrinking, and tape that down, you can take your blade and cut both pieces at a 45 degree angle at the same time...they should match up perfectly. That's pretty hard to understand, but I'll try to find some pics.

[Mark Wein]

That would be cool....I thought I would refurb this cabinet so I bought all the parts and it has sat there for half a decade

We might have just bought a house yesterday (had our offer accepted but nothing signed yet) and it has space for me to set up a small shop....this could be one of my first projects, although I would love to make some speaker cabinets from scratch, too.

Right now my table saw is buried in a corner of our garage

[Prages]

Here's a photobucket album about cutting the corners for tolex.

The pictures are in reverse order, so start and the end and work your way up.

http://s238.photobucket.com/albums/f...%20a%20Corner/

[Mark Wein]

Awesome!