Mesa Boogie Mark 1V Combo - Makeover

This beast turned up and was dumped on my workshop bench by a big burly bloke who wanted me to split the head and speaker into two separate cabs. This thing weighs a ton so first thing i did was to do my back a favour and pull the whole thing down into bits. I started to measure things up to produce a working drawing of the head.

The speaker cab is to be an Electrovoice design, the TS806. This cab is a small ported unit designed to take the EVM12L speaker housed in the little number below. In my estimation the boogie combo is not that much bigger than a Blues Junior but it weighs in at a massive 35kg's, a heavier lift than the dreaded Fender Twin, a well known back breaker.

As it came to me below left, as it left me to the right - I have written a detailed log of the build below including plenty of images so check out how it was done.

the plans for the TS806 speaker cab are public domain - download it here
 
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To find a bunch of well figured boards of sufficient width is pretty much impossible in Melbourne these days, so I opted for smaller widths of a medium light hardwood, Black Walnut, which is known for a decent display of nice grain swirl After an exhaustive search for the right timber for the job a quantity of black walnut 200x50 x 1.8m rough sawn boards were purchased from Brittons in Dandenong. There they are below sitting beside the bench. First job was to feed them through the buzzer to get the roughness off and see what I had.
 
 
All looked pretty nice but with rough sawn boards there is a decent percentage of waste and this lot was no exception. Amongst it was a bit of decent ripple which placed in the right spots will set the finished job off real nice. Next task after the buzzer was to chop them down to project size boards of 900mm. Then came the job of matching the grain.
 
 
Sorted it all into matching pairs, cut the boards down into roughly the right lengths for sides, tops and bottoms. Grain matching was quite good throughout and I am starting to anticipate a very striking looking finished job. Next task is the arduous task of sanding all the boards down to around 20mm. With a new belt in the drum sander I started poking them through. What we need at the end is a set of boards all of exactly the same thickness. After the final sanding of the edge joined panels a target thickness of approx 18mm is what I am shooting for.

NB By the way when I say "we" I mean me and the two dogs as they often call into the workshop to see how things are going and to hopefully find a stray corner of stale pie or bun or some other doggie delicacy laying around.
 
 
Below yoiu can see the whole pack of boards sanded to thickness. Next is to edge dress the boards, cut the biscuit slots and lay them out ready for glue and clamp up
 
 
Again the full pack after glueup and ready for the final encounter with the drum sander. No matter how carfully you clamp up the boards, even with biscuits to help with alignment, you get some creep and the edge joint is not perfect.
 
 
A few passes through the drum sander levels it all out again and the joining line disapears. Overall I am very happy with the way these panels turned out. The grain matching has been very successfull and the panels look as though they were cut full width. Below are shown the two sets of panels which have been ripped to width and one end squared,
 
 
The outward faces and front and back orientation have been selected and marked accordingly. At this point it is back to the drawing to double check the measurements. Then the amp chassis will be laid out on the roof panel of the head to check clearances. I always think of people working on the job after me and there is nothing worse than trying jack a chassis out of a cab that is fitted too snug. It needs to slide in and out with ease but the clearance cant be so great that its a really sloppy fit.

Once we have the clearance dead right the tops and bottoms can be cut to length for both cabs as the head and cab need to be the same width.
The sides can then be also cut to length.
 
 
Finally made the critical length cut for the head top and bottom. Had to have some clearance between the chassis and the side walls but not too much. Need to allow for a little pins overcut for the through dovetails. Ensure there is still clearance after the finish is applied. So very accurate measurements are required.

The head and cab needs to be the same width so all the tops and bottoms were cut plus while i was at it on the table saw I chopped up the walls as well.
 
Below: Cuitting the dovetails - I use through dovetails for strength. I use a Leigh D1600 Jig and a small Triton router. Reasonably easy to use and accuracy depends on how carefully it is set up.
 
 
Below: The cab sides with the pins cut - you can see the top with the tails cut.underneath.
 
 
Below: After a frantic half hour the cab is together in the clamps.
 
 
Below: Out of the clamps and it's a quick check to see if all the measuring worked ok and
It did - I have 1mm clearance either side of the chassis - perfection
 
 
Below: After planing the sides flush, sanding down the nibs, and taking out the cutting lines from the drum sander its time for a photo. The cab is pretty roomy back to front as I want to get the fan well situated so it can provide the unit with plenty of airflow. With those big 6L6's glowing, the transformer heat and the amp cranked up on a hot stage, it is going to need cooling. The boogie Mark 1V is a real beast of an amp.
 
 

As the job moves along I am gathering the bits and pieces for the fit off and one problem has shown up. The chassis mounting bolts are a #8 32 which is a mongrel size here in Australia. I have found some 25mm hex drive but really need 30mm pan heads. Still need to do some hunting,

Next task is to cut the angle on the head front then the hole in the head floor for the reverb tank. I worked it out all pretty close as there is a lot to be packed into that head. I then allowed an extra 5mm in roof hieght.

It looks a bit taller than the commercial heads but I am better to err over size than undersize. By my calculations there should be enough to pull an output valve out with maybe 10mm clearance. They will be directly above the reverb tank. The head will stand just under 250mm, the cabinet 368mm.
 
Below: Cut the back panel - mmm look at the fit - the TL806 drawing specs the back to be glued down and airtight - this will be water tight.
 
 
 
Below - there's the cab with the ports built
 
Below: The cab is fully trimmed out and now I can glue down the back - oh yeah - cut the 20deg front angle on the head
 
 
Below: another shot showing the angle a bit better
 
 

Below: After a frantic 10 minutes the back is in - glue seeping out all round indicates a good seal. The fit was tight and with glue on the wood starting to go off and swelling slightly adds extra friction.

You gotta just dive in quick, have a rubber mallett for extra encouragement handy and your clamping strategy worked out. Check that all tools required are within easy reach so you don't do the dance of death jumping around the workshop uttering a string of obcenities looking for a crucial tool.

 
 
Below: back on nice and tight.
 
 
Below: Everything with this job has been impossible to find - a small piece of 18mm marine ply - easy you reckon - no way unless I wanted to spend $150 to buy a full sheet.It's not something I use a lot of as most of my cabs are low power where 12mm is heaps. I ended up laminating 2 sheets of 9mm. There it is in the box - evrything is a nice snug fit.
 
 
Below: Cut the speaker port - hope it fits right.
 
 
Below: and of course it does. I will glue down the baffle and use the original course thread black scxrews to mount it.

Next comes the "Blackout" Everything that will be visible behind the grill gets a coat of black matt then a coat of satin clear, Don't want any light reflecting back from under the grill. This one is almost ready for stop, sand and prep for the spray used guitars.

Next job is fitting out the head. Still waiting on those special thread bolts from Perth before I can do much more.
 
 
Bellow: Finally the 8-32 machine screws arrive from perth and the job of locating and cutting the chassis mount bolts can be cut. It all fall into place nicely.

The successful completion of an entire project such as building a headshell and cabinet like this is the sum of hundreds of accurate measurements and careful cuts. Some cuts are easy, others take a considered approach. Some cuts are in the mind for quite a bit of time as a simple approach is found. If it is easy to do it is more likely to be right. Cloud the job with unnecesary steps and complicated procedures and success is less likely
 
 
Below: Next comes measuring up and roughing out the mount hole for the reverb tank. Not exactly the same as the original Mesa head shell but it willwork and allow a decent airflow up through the bottom of the cab. Seems awkward cutting a big slice of the base out but there you go, it does allow a bit more space inside. I've started with some 3/4" holes at strategic points.
 
 
Below: Roughly hacked out with my trusty jig saw.
 
 
Below: Set up for the cut on the router table.
 
 
Below: Nice neat job and the tank fits in pretty good. I cut some mount holes so I can mount it on machine screws into teenuts in the bottom of the headshell Boogie style. Sorry for the crappy pic
 
 
Below: Tape on the template to cut the handle holes
 
 
Below: Screw it on to make sure it looks right. All that is left on this job now is the front panel mount and pedal board holder cleats to be fitted. A small section needs to be routed from the rear of the walls to allow finger access to the holding screws on the pedal board. If you don't know this particular amp, it comes with a large pedal board the same width as the headshell interior and it mounts accross the back for travel. It is held in place by a pair of easy release holding screws. Getting close to prepping this box for the spray used guitars.
 
 
Below: A bit further along withchassis mounted, reverb tank in and the fan on its mount. At the rear the pedal board mounts will fit in perfect. Not much room iside for leads though. It may be worth having some keepers on the back to wind the power lead onto. I would want a good half hour cooling time before i started stuffing rubber coated leads in amongst the hot trannies and valves
 
 
Below: Finally got into queue at the spray used guitars. I don't have a registered spray booth here where i am using waterbased lacquers and sealing oil. I have to farm this finishing job out. A bandmate is a furniture polisher and he has a contact that does all his two pack work. There is very stringent regs here in Melbourne regarding the emission and disposal of toxic byproducts generated by the two pack finishing process. A lot of places on the planet two pack has been outlawed for years

Here is the job prepped for spray - Just a round of tape is required at the back of the headshell - the interior will be done here in black after the two pack is applied.
 
 
 
Back home at last - I won't go through the awful tale regarding the spray job. Surfice to say after everything it ended up being a total knockout

Below: A few shots of these babies in the high gloss two pack finish
 
 
 
 
 
 
 

After a little break it's time to get on with the job of fitting off. First job is a measure up for covers and shoot that off to the client. I have recommended Julie Kemp at Tender Loving Covers

Next on the list is to fit out the headshell. A little tricky and I need several trips down the street for different size bolts etc as earlier calculations didn't quite work out plus I made a couple of last minute changes in the way the reverb tank was mounted. Although very tight with not a mm to spare, I ended up with an excellent result as you will see.

I remember at the start of the job scratching my head as I carefully put together the interior plan for the headshell. Without the couple of low res reference shots of the interior of a Boogie short headshell, I would never have believed it would all fit inside such a small space.

Below: There's a shot with the bottles in. I will route those stray wires towards the front away from them. The reverb tank [Acutronics long tank] is suspended directly from the floor and protrudes through the cab. There is enough clearance to the deck as I have used 28mm rubber door stops as feet. I shielded the underside of the top with aluminium foil. I also sheilded the top of the cab with aluminium flashing to minimise amp noise.
 
 
Below; This is the top shot of this project for me. Everything fits in the cab perfectly including the power cable.
 
 
Below: Heres how it looks from the front. Those 2 brackets sticking up on the front of the fan will screw into the front baffle.
 
 
Below: A shot showing the glorious figure in that top slab of walnut
 
 
and another
 
 
Next job will be cut and cover the grill plates. The Speaker plate is tricky as there is not a lot of space around the speaker to attach it to the cab so a little careful work will be required there. The speaker ports will need to breath and that will leave not much to attach the wicker cane grill material to. I have had some time to carefully consider the technical side of the plate job and will be able to achieve a very workable solution.It will need to be carefully laid out and I may make a template to speed up the job of cutting the next one.

The plate for the headshell will be a doddle. It will mainly be an exercise in ensuring my measurements of the thickness of wicker cane stretched over a frame are correct. I will cut some breather holes to allow air to the fan from the front even though there is plenty from the rear.
Quite a deal of work in the grill plate for the speaker box though.

Below the grill plate in the headshell
 
 
Below A tantalising first look:
 
 
below: At last both cut and covered
 
 

below: the rear view of the speaker grill plate. The wicker is cut to size then soaked for 30 minutes in water. This softens it up and makes it nice and pliable. Once stapled down it will dry and tighten quite a lot. It is tricky to push round and get it on real tight but after it shrinks up it will be tight as a snare drum head. After 24 hours it will be tight enough to trim up.

The cane still needs to be trimmed back but now its scotch o'clock and I will start on the run home tomorrow mnorning. It is getting close to the time when this project and I will at last part company.

The way it is cut at the corners leaves a few daggy bits hanging off. These are carefully woven back in or just super glued down so it all looks nice and tidy. A further 2 hours or so in the drying cupboard and it is ready for a very light mist of nitro just to give the surface a little protection. I was hoping I wouldn't cut myself and get blood on it before iI got the lacquer over it. Apparently blood stains are impossible to get out.

 
 
Put some fibre blanket in according to the EV plan. Speaker lead is visible. After this the speaker is dropped in the hole and screwed down tight. The rubber feet are also in place.
 
 
Popped the grills in just to get a look at the effect of the whole thing.

JUST 16 SCREWS TO GO.
 
 
By the way, i am glad I don't have to hoik this bad boy around, definitley a young blokes amp.
Following are 3 pics of the finished job.