Bloated speakers/weight wise

Onhwy61 wrote:

"The easiest way to limit the cabinet's output is to make it massive and less likely to be sympathetically excited. There are other ways to make the cabinet highly rigid and inflexible, but they are expensive (contrained layer, exotic materials, etc.)."

I don't agree that it's as simple as saying that making something massive makes it "less likely to be sympathetically excited". What that does, all other things being equal (which they're often not), is lower the frequency at which sympathetic vibration occurs. I don't pretend to have anything like a comprehensive grasp of the subject (and seriously doubt that even many speaker designers do), but do feel it's a lot more complicated than just adding mass to deal with the problem. Shape, size, density, points of contact (for both damping and exciting elements), materials' intrinsic damping and rigidity properties, all go into the mix. If you add mass in the wrong shape or the wrong location or use the wrong material, resonance will worsen instead of improve, only shifted in frequency. Mass in and of itself isn't the answer to anything in this area, it seems to me, and if you can achieve the same intended result while using less mass I think it's always better, and not necessarily more expensive all things factored in (weight has its own costs).

Zaikesman, I agree that it is more complicated than my earlier post presented, but I don't think I'm incorrect in stating that adding mass is the easiest and cheapest way to deal with cabinet vibration. It's not a perfect solution, but it does work fairly well. Going from 1/2 inch to 3/4 inch MDF or doubling up layers of MDF (or plywood) is a tried and true method to increase cabinet rigidity. There are better ways to achieve the same end like CNC milled aluminum, carbon fiber layers, concrete over wood, or even the interlocking jigsaw pieces as used by Sonus Faber. You could also take a completely different course and go for a cabinet thats extremely light yet sufficiently rigid with the goal being a very quick dissipation of the drivers' backwave energy. Any of the alternative methods is more costly than the somewhat unsophisticated approach of adding mass. It's a brute force approach to solving a problem, but that doesn't mean it's ineffective. Again, as I stated earlier, adding mass has to be part of an overall speaker design concept. Used in an non-optimal context adding mass has little positive impact.

At the very moderate listening volume I hear my music, it would make very little difference if the cabinet were 1/2 inch or this 3/4 fab wood. I guess if I had the bigger 8 inch, or 10 inch Seas, then maybe a mid SPL there would be at least some advanatge. If I A/B at low low/mid volume, its doubtful anyone here could definetly say this is 1/2, this is the 3/4 unless by lucky guess. Feel free to disagree. I think some labs make big and/or heavy speakers just to try to impress and feel like you are getting your moneys worth.
Since we are on the subject of over fatty speakers, sorry if some are insulted, is the lab that loads in more than 3 drivers per cabinet. Like some sort of 4 , 5, EVEN 6way!! :-0. I recall going to the New Orleans audio meeting at a local audio shop, there they were, the big funky Legacy Towers. Took me back to the early 70's. Man, what a speaker, what a 'sound". Price was at some odd thousands of $'s. duh

Did I just see Ecruz mention a speaker at 1/2 ton. Well of course its not home model

Actually they are home speakers, Magico Reference. I saw, and heard them in an A'gon member AudioEzra's listening room.

I guess I look at going from 1/2" to 1" or 3/4" to 1 1/2" MDF a little differently than simply saying it's adding mass. Yes, of course it is adding mass. But more to the point, I think, is that it's changing the ratio of dimensions by doubling the front to back wall thickness (plus it also often entails combining two layers with a an adhesive in between, a form of constrained-layer damping). This is primarily where the extra rigidity comes from. (Think of an I-beam -- it can nearly as rigid as the same dimensions of a solid bar, but is obviously much less massive, which can actually make for a stronger structure for practical purposes.)

And achieving higher rigidity itself is also not always the same thing as reducing resonance. Very non-rigid objects can be the most non-resonant objects -- think of a down pillow -- depending on their form and density. Increasing rigidity raises the resonant frequency (again, all other things being equal, which they likely won't be). Of course higher rigidity in a speaker cabinet is a good thing from a wavelaunch perspective. But without proper attention paid to shapes, sizes, damping, points of contact, etc., higher rigidity in itself might not reduce resonance but only change its character. Overall, to my mind both higher mass and rigidity are probably somewhat overrated compared with self-damping as means to achieve the design goal of a quieter cabinet, and probably more expensive as well, but for the fact that most manufacturers are already set up to deal primarily with MDF.

I thought the Sterophile measurements of the new Mordaunt-Short Performance 6 speaker, that's made of a combination of molded structural foam of varying shapes, thicknesses and densities plus reinforcing metal elements, was fascinating. The result (achieved at the initial cost of a reported 10,000 hours of design time and who what tooling costs) is a 48" tall, 18" deep at the base speaker weighing only 66 lbs., and yielding some very impressive accelerometer results in JA's cabinet resonance tests, with low amplitudes, no dominant frequencies and extremely short die-away. They cost $6,500, not really an outrageous price for an imported, high-tech, nearly full-range 4-driver floorstanding flagship, and the molded-contoured form probably means it has better diffraction properties than most MDF boxes to boot. Of course all that doesn't necessarily mean they sound great, but I do want to hear them if I can.