I'm installing in-cabinet M60's into a wall, 50 lbs each. I was going to create a shelf, or ledge, to support the 14 inches of the speaker that hangs out of the back of wall.

I'd be peeling back the dry way on the *opposite* side of the wall and build a nice ledge, using 2x6's that bolt to the wall studs, also triangulating to the same wall studs. So the weight of the M60's would not be a problem. Once I was done, I bet it'd hold a car.

BUT, what about accoustics and vibration? Would I be better off building a "stand" - where most/all of the weigth is directed vertically to a concrete floor about 3.5 feet below speaker bottom?

Your advice is much appreciated!

As long as you frame the opening as you describe, I don't think it would make one bit of difference.

hmmmm. I know some people go wild making stands filled with a hundred pounds of sand or lead shot...

of course, a shelf/ledge would be alot easier for me.

The ledge idea sounds good to me. If you're worried about vibrations you could use a buffer between the ledge and the cabinet.

the speakers do come with a rubber mat they sit on. It seems to do a good job of isolation, although mine are currently sitting on a box filled with sand...

maybe I'm worring too much.

If I build a shelf, and for some reason I think that's not working, I can always run something down from bottom of shelf to the contrete floor below it.

thanks for the input guys.

Whoohoo Lego !

Seriously though, a question. Are you referring to the 60s designed for in-wall placement or are you placing actual, freestanding M60s into a wall cabinet? If so, you may suffer a bit of negative effect as their design, including rear ports that need some room to breath, were not truly intended for a cabinet placement.

Honestly though, I'm not qualified to tell you how much effect or how much it will matter to you. I'm just repeating some of the stuff I have learned myself from this forum and some other sources.

correct - I'm using the front-ported only m60's designed for in-cabinet use.