THAM 15 - Touring Version! (and matching top)

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Hey all

This project has been in the works for a while now, being planned and the false started a couple of times!  :-)  But now in the last week or so I’ve got to make some proper sawdust and it’s on the way to actually coming alive its time to get some pics up. 

So below I present my touring version of the THAM 15 

Now, before I go any further I have to give a huge thanks to Tony Wilkes. As well as supplying all of the drivers at great prices for me (its fully BMS loaded) he has been a great sounding board for discussing ideas, has supplied laser cut and powder coated metal for the rear connection panels and for the connection panels of the amp racks and CNC’d lots of jigs and templates which have been a massive help with the routing. So this is just as much a product of his hard work as it is mine! 

It actually started off as a very different project.  I was in the middle of planning a much bigger system with 18” horn subs and hornloaded MT-112/122 style tops. However, while it was being planned and designed and I saved up for the drivers, I wanted to use up some other bits and bobs I had and make some small cabs. 

A while ago Tony had been kind enough to supply me with some 15” drivers (15N830) at really short notice to fit into some bandpass cabs I had that were blown and couldn’t get a recone for. They went into the bandpass to get through a few gigs but I had always planned to make a Tham15 cab for them cos although the bandpass was surprisingly musical for its ilk, the THAM would be an improvement. I also had four 4550 comps from a separate project that didn’t happen, and thought that doing two THAMS a side plus two double 10” tops (as wide as I could go and still stack the two on top of the sub) with the 4550’s a side would give a nice wee system for smaller band work. 

However as always these things take on a life of their own and grow and grow.....

So if i’m ALWAYS gonna use both cabs per side on top, why not just make it one big cab with the four 10”s together, then I could look at some fancy push pull stuff. But I’ll then need just one big comp on a big horn per side rather than two (forgetting that the whole reason for this was to use the comps I had). But now if it’s one big cab I don’t need to worry about width so why not use double 12 instead, with much better sensitivity and power handling. If I use really good 12” I could probably even match it up with three THAM’s per side. But then with the 12” one above the other the stacks will be just a bit too tall for their intended job of small to mid live gigs, so they’ll have to be horizontal in some sort of V-config.......

LOL on and on I went somehow justifying it to mself every time the level (and price!) went up, and played about with plans until I decided I was building three THAMS a side with a powerful top that has two 1000w BMS 12N802’s in it as well as the 4592 coax comp on a very controlled Beyma  TD400N horn.  In a way the tops are very similar to Tannoy VQ top cabs (except for using two 1K drivers instead of two 500w obviously) but they got there all of their own accord it was never planned that way :-)

Then it came to handles. I had always planned to use the three stacked on their sides to stack to the correct height, and was always gonna extend the sides to have a full face grill rather than just over the small mouth area. Wheel base was always gonna fit in against the grill for transport, so it meant that the obvious place for the main handles was on the small ends, what would be the top and bottom when sitting in its original designed confifguration. 

However after playing with various designs of both handles cut into the sub with back boxes and metal handles inserted into the face, I couldn’t find anything that didn’t leave me feeling like I was taking away a bit too much of the horn path, especially on the side that the driver fires into. 

So my only other option was to then build out the way and extend the box. After playing with several ideas I took my inspiration from the kind of flying frame that you see on some line array cabs, where the metal frame acts both as the flying support and also a large bar handle. Little more playing with various design bits and I ended up with what you see above. 

Then set up to play, the main bar handle is vertical and when the wheelbase is set into the grill and the cab is flipped forward 90 degrees onto the wheels this obviously becomes horizontal. But the advantage is that the rim that runs all the way around the actual bar handle also acts as a handle in itself, and so the cab can be picked up solidly in any orientation. In the centre of the top face, you can also see an extra small handle cut into the sub face along with the guides for the feet when stacking (and a matching handle on the underside) and these give an extra place to grab should you happen to be picking it up from a funny angle. 

The subs have runners underneath that sit into the channels on the top of the one below, and the tops will have four rubber feet that will sit into the circular indents. 

The tops will also have the wheelbase fitted in the same way and so best place for their handles was also the ends. I wanted to keep a matching design to make them a set, so they have main carry handles on the top and bottom (which become the two ends when on the wheels) and also have more traditional handles on each side to grab while being stacked and set up/taken down. 

They will  have a single piece of fly track set into the top at the front (the single round indent) that can have a metal hoop clipped into, and this gives a place for a ratchet strap to run though if they’re used somewhere windy or unstable and need to be tied down. They’re set right at the front so the ratchet strap then runs over the flat bits at the front of the sides (rather than the trap parts where it would naturally try and pull itself back). And the runners of the subs are positioned just far enough back so that the ratchet strap can run down and under the sub below without getting in the way of the runners sliding into their mating grooves. 

As they will always be used with the subs, they didn’t have to play especially low and so the rear chamber for the 12” is pretty small and they’re tuned relatively high, with four rear ports which should get cold air right to the magnets. They play flat to about 80 or 75 and then drop off a cliff, but this is more than enough to play with as they’ll be crossed over somewhere between 100 and 120 (depending on how it all sounds together when I start to tune them) and so they play well within X-max right up at their full 2K per cab. The 802 is a great driver which seems to be a good balance between a super light coned , low x-max 12” for a horn (such as the BMS 810) and a beefy but heavy high xmax heavy 12” that is more for low-mid and bass in two way full range cabs, so should be extremely quick and punchy but still have some balls when needed!

So yeah it’s all finally coming together. Wood is cut and i’m about 80% of the way through the routing  (pretty much every single joint is rebated so there’s a LOT of it!) so I’m hoping that as long as the weather holds out and I can get out in the garden for a couple of days and get them done they should be at least fully glued and screwed together by the end of the week, and i’ll have made a start on the filling/sanding/prepping for painting. 

Edited by kevinmcdonough - 26 July 2011 at 1:44pm