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In Reply to: Re: MMG Crossover Upgrade (yeah, another one) posted by Dawnrazor on December 7, 2006 at 21:51:58:
Those things clamped to the edges of the panel are 1" square aluminum tubes covered in vinyl damping sheets. Holes drilled through the tubes & speaker frame, T-nuts on the front of the frame.
The aluminum tubes when covered with damping sheets do not ring at all and when bolted up to the MMG frame, take away about 95% of the panel flexing.
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Hey Rick,THat is on of the many things I have planned.
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Hey, that's a nice way to beef up (or should I say create some?) the rigidity of the MMGs! I have plans to address the issue in a slightly different manner. I constructed metal stands for my MMGs atop of which is a piece of 1" oak plywood. I used 10" angle brackets (hammered square - why are none of these things 90 degree?) to affix the MMGs to the plywood. I plan to use the area above the plywood as a crossover enclosure. I also plan to remove the trim from the sides of the MMGs and replace it with a sheet of oak that arcs to the rear of the crossover box starting about 2/3s of the way down the side. I hope this makes sense. When all is complete, I'll post some pictures. Perhaps I can Photoshop my idea and post that in the meantime - that is, if anyone is interested.
I'll show these again of my MMG reinforcement efforts.http://i19.photobucket.com/albums/b186/RodH/2006_0413march20060007.jpg
http://i19.photobucket.com/albums/b186/RodH/2006_0413march20060008.jpg
http://i19.photobucket.com/albums/b186/RodH/2006_0413march20060009.jpg
BLOODY BRILLIANT!I looked at your photos and absolutely LOVE your idea. The bad news is that I'm now beginning to rethink my own plans (grrr). I've filed your pictures on my computer for future reference if my completed project doesn't strike my fancy.
Thanks for sharing.
Below are a couple of shots indicating where I am presently and illustrating, albeit VERY roughly, where I am going. My new crossover components will arrive Monday - I can't wait!
http://members.cox.net/kpcrowley/P0002223.JPG
Thanks for the pics. It looks like you have made yourself plenty of room and access to experiment with the crossovers!Anything you can do to make the MMGs more rigid should pay off, and your idea looks very interesting...almost Linkwitz Orion-like.
Rod
I'll have a sizable enclosure for the crossover, but it isn't a perfect environment for the inductor. There is a steel plate to which the plywood is screwed. The back 5" of the plywood has no steel beneath it, but the 10" angle brackets (and why are none of those things square when you buy them?) extend a little closer to the rear. I'm concerned about coupling effect with the foil inductors - maybe I should have gone with Erse Super Q inductors instead.On the other hand, I *could* just mount the coils on their sides directly above the steel and probably get inductor values approximating 2.5mH! Then all I'd have to do is add some more capacitance to have crossovers tuned closer to the MG12 specs. I'm really only kidding, but I wonder if that would work.
Pictures always help over the internet.
Here are a couple of photos of the MMGs as they currently are (a work in progress) and a very roughly edited picture that illustrates where I'm going. I'm working (slowly) on the woodwork. I think you can see what I have in mind though.BTW The DVD player in the cabinet is a temp while I decide what to do. I'm trying to decide whether I should have a Pioneer Elite DV47 universal player repaired or just bite the bullet and buy a new player - Marantz?. I had to have something in the meantime and that little Sony was dirt cheap.
http://members.cox.net/kpcrowley/P0002223.JPGhttp://members.cox.net/kpcrowley/P0002221-rough-edit.jpg
Cool stand idea.
Don't laugh - they were formerly attached to tables. I was with a friend who was looking at used furniture when I saw a couple tables that swiveled - that little light in my head started to glow, so I bought them. The things are made of steel and are fairly heavy.They were too tall, so I cut 18" off the posts and cut and threaded the connecting rod. The feet were also too long, so I cut them off 8" from center and welded them to a new piece of 1" OSD pipe (I just made a wooden jig to hold everything square for welding). Then I removed and tossed the plastic carpet protectors and drilled and set some spikes in the ends.
The only thing left to address was the finish - didn't want the bright, shiny metal. I used Duplicolor's smoke anodized finish spray paint (prepping first with adhesion promoter). It worked great and stands up to being tapped with a screwdriver.
The good news is that my final cost was about $60 for both stands. The bad news is that it was quite a few hours of labor. But then, as I mentioned elsewhere, I find this kind of thing a heck of a lot of fun. I may shorten them a little more - 12" at present.
That speaker wire was an adventure as well. I bought some litz cables in Germany 26 years ago, but the silver leads didn't hold up well and they ended up in a drawer (I hated the idea of pitching them). One day I came across them and decided to make some custom length cables out of them, so I bought a melting ladle and fired up a plumbing torch. I melted down at least $20 worth of WBT 4% silver solder (I love that stuff) and started dipping and skimming. It was a messy task, but it worked beautifully. Like I said, I like to tinker!
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