colterphoto1 Posted September 2, 2008 Share Posted September 2, 2008 I have two sets of the dreaded MCM stacks, one was purchased in Atlanta in spring 2006 and was personally ferried back to Indy by myself in a 5x8 UHaul trailer. They were toured through the southwest by a R&B outfit and ended up in the hands of their drummer. His wife wanted them out of the garage. One of the standard (double 15) bass bins fits exactly in the back of a truck bed and we managed to get the rest in the trailer. The 5x8 size is necessary in order to get the 44" wide MWM in the doorway. There is not room for two MWM's so one must travel elsewhere. This set has been sold to a Forum member and I have promised good operating condition with new K43 woofers installed. This thread chronicles some details of the MCM stack inspection and refurbishing process. Here we are with the traditional handshake before moving out with the load. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 Later that spring some intitial inspection would take place. This was shown in another thread so I'll not take the space here. These stacks were purchased knowing that there were no woofers installed. Here are brand new K43 woofers still in box, ready for installation. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 We'd played one stack of cabinets during summer of 2006, I'd installed one of my EVM-15L drivers. Inside we see it and the rather poor wiring leads that were wrapped and electrical taped together. I'll remedy this with butt splice and slip on Amp connectors to the speakers. I'll leave the internal 18 ga wire as the posts that feed the wire through the internal cabinet walls are a pain to get to (being inside a very tight opening with slotted screw head that would have to be accessed with 2" clearance). Most speakers that I buy that have aftermarket woofers have been abused in this fashion. Whether it's soundmen in a hurry for a fix or just a repairman without a soldering iron I cannot say. Also CHECK THE FUSES- nearly all Klispch pro gear that I purchase has the 20 amp 'test' fuse still installed. A K43 driver will successfully protect anything above a 4 amp fuse. General rule for fusing Klipsch Pro ALL mid/tweeter section 1 1/2 amp 12" non pro driver 2 amp 12" pro driver K42 2 1/2 amp 15" K43 and others 3 amps 15" dual or 18" driver 4 amp (NOT 5 amps as the MWM cabinet states) Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 Just like in the LSI bin and single MWM-S bin, the cast frame K43 driver is just a bit too large to fit. I'm used to this procedure, having stolen the older steel framed K43's from my LSI's to use in my KSM2 monitors (see other thread). I use a 60 grit sanding belt and grind away 1/8" flat on each of two ends of the basket frame. Take care to note where you are grinding. For MWM bin I was able to install one woofer complete without modification, then ground two sides of the other woofer. On MWM you grind adjacent to screw hole, I think for LSI it was in the area directly between screw holes (it's however the flat panels of the cabinet line up with relation to the bolt hole pattern. Brush or blow any aluminum debris away and install woofer using 4 1/4-20 x 2" machine screws. Here's a closeup showing the woofer modification. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 On the MWM cabinet, each woofer has it's own input binding posts and fuse holder. Let's make sure that things are in phase before closing the woofer door, mmmk? I took a dual banana jack, removed a set screw and installed a longer bolt. To this I clamped an alligator clip with 6' line attached. I'll run this to the front to check for continuity on the positive side, then the negative- marking the wires clearly with tab of red tape so future owner knows what's what. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 Next I wrapped the butt splices in tape so they wouldn't rattle against cabinet walls and clipped on the Amp quick-connects. I favor this original method of connection vs soldering in case the future owner wants to experiement with different woofers. I squeeze the Amp terminals down slightly with needlenose plier before connection so they are tightly attached. Now to the really nasty part- the woofer door seal- ugh! Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 In the previous photo you can see where the woofer door gasket material has been scraped off. This stuff is extremely nasty and over years and with heat has turned into gooey mess of tar-like glop. Some is hard with age and nearly crystalized, other leaves black marks everywhere it touches. I sharpened the edge of a putty knife and scrape with the wood grain. it comes right off with a little patience. Make sure to have some really great tunes cranked through your garage LaScalas while performing this procedure, it helps. Here's some of the gunk after removal. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 It's somehow fitting that I'm using Grandpa's old milking stool while working on these venerable beasts. After all, the 'Magnificent Woofing Machines' were first tested in a cow pasture in Hope according to legend. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 woofer hold-down bolt tightening tool. You want to get those torqued good and tight. I suppose it would be simpler to do this with the speaker in the face-up position, but working alone I didnt' have the desire to unstack and restack the entire rig by myself. I found that after hand-tightening, I could get about 3x 1/4 turns further before I heard wood creaking. That's where you want to be. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 I used Parts Express number 260-540 speaker gasketing tape. It installs and works easily, compresses fully and gives a great seal. I've used one 50 foot roll and done 4x MWM-S cabinets and these 2 MWM cabinets. One caveat- it's rather stretchy so be careful to lay it into position and then press it down. Do not stretch as it'll shrink back and you'll have air gaps at the corners. I got a little fancy here and put extra corner bits in to help with the seal. Here is one MWM cabinet with tested wiring, new Amp quick-disconnects, factory fresh K43 woofers and new woofer door seal. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 the other one Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 2, 2008 Author Share Posted September 2, 2008 final cleaning of any crud prior to buttoning them up. Quote Link to comment Share on other sites More sharing options...
Moderators dtel Posted September 8, 2008 Moderators Share Posted September 8, 2008 [Y] I love the MWM cabinets, a simple but efficient design. Quote Link to comment Share on other sites More sharing options...
Marvel Posted September 9, 2008 Share Posted September 9, 2008 They are so simple, I plan on build a set of the singles. Michael, is that a six inch slot in the baffles? Bruce Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 14, 2008 Author Share Posted September 14, 2008 appears to be 6", I'll measure tomorrow for ya Bruce. Doesn't look like any difficult angles like the LS bass bin. I think doable. Mission Accomplished btw, these MWM's along with other components of complete MCM1900 arrays were sold to a collector and Forum member in our southern states. I hope he enjoys them! They travelled from Atlanta to Indy, were stored here for 18 months, then travelled another 750 miles to Hope this past weekend. I'm tired of humping them around! LOL Good thing I kept a set of stacks with MWM-S bins (that's the nomenclature for single 15" W bins) Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 30, 2008 Author Share Posted September 30, 2008 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?) Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 30, 2008 Author Share Posted September 30, 2008 Photo showing size of throat opening as 7" Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 30, 2008 Author Share Posted September 30, 2008 construction detail showing 3/4" stock as reinforcment and glue/nail blocks throughout W bin Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 30, 2008 Author Share Posted September 30, 2008 Detail of bakelite wiring pass-through from horn jack cup at rear of cabinet, through horn throat, through the horn wall into the woofer back chamber. This is the same terminal type as used in Heritage speaker connections. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted September 30, 2008 Author Share Posted September 30, 2008 throat showing position of jack cup in the center of the back panel. There is a fuse carrier for 3 amp fuse. Some of the earlier panels state 5 amps but this is incorrect. A K43 will blow before a 4 amp fuse will so a 5 amp fuse offers no protection at all. In the double woofer MWM bins, each woofer is wired separately to it's own fuse and input terminals. All MCM terminals are standard 5 way binding posts. (note- photo is tipped on end) Quote Link to comment Share on other sites More sharing options...
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