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MWM rebuild


colterphoto1

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The single is fine. I can extrapolate from there.

Enjoy your Saturday man. If you ever pull them out.......and you have time.

Heck...mine are tucked away in storage. I can't even get to them.

jc

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  • 5 weeks later...

I have all diagrams saved for printing. I'll spend some time in the shop tomorrow and measure everything.

Question as to how to adjust for the aluminum trim- should I attempt to deduct that thickness everywhere it occurs so as to have a measured drawing for cut list?

M

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Ok, just to put all MWM dimensions one one page, here's the back box details as given to Bruce.

A - backbox depth from front of cabinet to woofer side of back board = 123/4 or 12 internally. Note that the back box door does not come quite to the front edge of the horn, allowing some space between aluminum trim to get door slid into place.

B is derived as J - F (see next drawing) or 42 1/16 - 34 1/4 = 8 13/16

C - backbox width, exterior is 17 or 15.5 internal.

Here's a diagram provided by Bruce. First the slot for the woofer is exactly 7". The motor board has it's corners clipped at 3.5" in from either corner, this allows the area behind the throat to be utilized as more back chamber volume. This leaves 8.5" of the square sides of the motorboard intact.

The bass chamber is 17 inches wide to the outside, 15.5" internal. The inside of the back chamber is 12" and there is a 1" offset between the chamber back and the front of the cabinet to allow space for the woofer door to be installed using 1/4"-20 x 2" FH bolts. Note that Klispch did not use standard T nuts in pro enclosures, they used a threaded plate that attaches from the inside with two wood screws. Nothing like threading a bunch of bolts into T nuts only to hear the last one 'plop' loose inside the cabinet (it's always the last one,isn't it?)

post-10755-13819445611298_thumb.jpg

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Here's the main diagram, remember that I'm measuring a MWM-S cabinet with aluminum trim and fibreglass mat covering. I have allowed 1/8 per trim thickness and this has already been subtracted from the measurements given here.

I've done some check figures but I suppose we can't know for certain that this is the beginnings of a cut list until someone lays it out in a drafting program to see if all measurements are completely accurate.

D is nearly impossible to measure but could be derived if necessary, unless you just need some sort of check figure.

E woofer back box to inside of mouth = 24 3/4.

F Back box, initial horn flare depth = 34 1/4 (+ 1/4 gap to front of horn mouth on mine- see note on A above)

G the clipped corners of motor board allowing the intial flare back space to be used as additional back box volume = 3.5" along each short side

H the internal measurement of back box space behind inital horn flare is derived as:

1/2( Motor board width 15.5) - 1/2(7" slot)) = 7.75 - 3.5 = 4.25" ( the horn side of the initial flare should smoothly contact the inner edge of the woofer slot)

I internal height of MWM-S cabinet 15 1/4" inside or 16 3/4 outside, total height of my stacked cabinets with trim is 34", reduce by 4(1/8) for the trim and it's 33 1/2 (exactly twice the 16 3/4 single cabinet measurement)

J internal bin depth = 43 11/16

K back width = 32"

L side = 48" (why no surprise there?)

M horn mouth width internal = 66 1/2

N horn mouth width external = 68 1/8 (slightly wider than M + 1 1/2 because of bevel cut)

O external bin depth 44 1/2

P woofer slot height (diameter) = 12 7/8 inch tall.

Q woofer slot height at minimum = 10 13/16

R woofer slot width = 7"

I think it's fair to say the jack cup is aligned in the center of the back side. If you want handle position measurements I can get those too, there is a single deep cup style all PVC handle on each side wall oriented so that the cabinet is carried between two men with the horn mouth facing upwards.

If any of this doesn't make sense, let me know and I'll correct it so we have everything in one place.

post-10755-13819445613408_thumb.jpg

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" Note that Klispch did not use standard T nuts in pro enclosures, they used a threaded plate that attaches from the inside with two wood screws. Nothing like threading a bunch of bolts into T nuts only to hear the last one 'plop' loose inside the cabinet (it's always the last one,isn't it?) "

Good idea should be no harder to find than T nuts anyway, I hope. What about that little plastic deal where the wires goes through the inside of the first section of the horn to where you connect to go to the driver, I think you called it Bakelite plastic ? What would be good to use in place of that, it's in a tough spot to get to if a wire were to come loose later ? Or just a hole barely big enough for the wire to go through, a tight fit.

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That is a standard Heritage barrier strip- 2 holes. Once the cabinet is assembled, it's next to impossible to get a screwdriver in there to attach wires it. There is a photo of the wiring setup on page 2 of this thread.You could run your wires through a hole drilled in the side of the first flare, then apply sealant if you wanted. Don't leave too much wire or it will rattle around and make you crazy.

Lots of guys have extras of these lying about from changing out the terminals on Heritage speakers.

The woofer attachement points are a little strip of metal with a threaded hole in the center and two screw holes that attach the plate from the inside. Total size about 1" x 1/2"

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When our school cabinet maker uses T-nuts, he will put a piece of wood on the back side that is screwed into the cabinet. This will hold the T-nut in place and prevent it from popping out. In other words, the T-nut is sandwiched in between two pieces.

Bruce

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