Should I proceed? Math versus intuition....

another carpentry tip.. if you use "twisty" nails ( not sure the proper name, but they are slightly spiral) that will also help to prevent the nail "creeping out". even better would be to rent an air nail nailer and use 2" finish nails with the preapplied glue. the glue heats up as the nail enters the wood and these suckers do not slip... just be sure to get the seals tight in the first place.

I've been procrastinating in my response to this thread because it raises a lot of questions that could conceivably require a book to fully answer. :) I still stand by my argument that alternating slat widths and varying the cavity depth will not "locally" widen the bandwith of the resonator. I know this basic principle very well in practice because the situation is directly analogous to a ported loudspeaker cabinet. A slot resonator and a ported speaker cabinet are both simply Helmholtz resonators. The resonance frequency and Q depend on the cavity volume, the port length, the total port area, and the damping. The resonance frequency and Q are independent of the cavity shape, the number of individual ports that make up the total port area, or the shape of the ports (unless the lateral port dimensions get so small that the airflow resistance significantly increases). Remember a basic slot resonator follows all of these principles. The only reason you don't find volume and slot (port) area in the design equations is this: The resonance frequency of a Helmholtz resonator is given by F0 = c*sqrt[S/(V*L)]/(2*Pi) Where c = speed of sound S =port area (slot area) L = port length (slot depth) V = cavity volume Now for a slot resonator with the dimensions H = height W = width D = depth Sa = slat width So = slot width We can see that V = H*W*D S = H*W*(So/Sa) Substituting these into the resonance frequency equation we get F0 = c*sqrt[So/(Sa*D*L)]/(2*Pi) Since the cavity volume and slot area scale with H and W they fall out of the equation. So, just because you find D instead of V in the design equation for a slot resonator doesn't mean that it isn't a Helmholtz resonator. It is and it follows the same principles with respect to port shape and cavity shape I described above. Thomas PS - Thanks for the respect Lee.

Hey Lee, NOW you've done it - didn't I TELL ya he was gonna GETcha? Thomas, I TRIED to tell him, but he wouldn't LISTEN, HONEST - read back and see - "I would be MUCH more concerned that you slant the fronts of your boxes toward the rear of the room than worry about varying slot widths - if you believe in varying slot widths, you should also believe in varying cavity depth - and the part that REALLY will work is the angled fronts. They will, if nothing else, help your flutter by non-parallelling the walls." See, Lee, I TRIED ta Tell ya... (OK, I'll go take my Librium now, don't put me in that room again...)

Steve, Steve, Steve! C'mon, I've already capitulated! I don't have enough time/money to build different traps and test them. (I *still* wonder about 2nd or 3rd order effects and interactions....<grin> but I'm not going to spit into the wind ;) ) I think my current approach agrees just fine with your modes and carpentry suggestions, Barefoot's math, John's details, etc. I don't feel like the 'foot stepped on me in any way -- I really appreciate the input, and my room will be better for it. I'm really looking forward to recording.... I think this room is really going to sound sweet! -lee-

Yeah, Lee, so do I - BTW, just in case you've not "sussed it out", I've been known to clown around a bit - like I've told Fitz (cadesigner) on a couple of occasions when he was wondering if I was mad at him "you'll know when/if that day ever happens - there will be NO DOUBT in your mind, because I'll either tell you to GFY, or never speak to you again, or both - and BTW, good luck on EVER causing that to happen..." Near as I can tell after studying this stuff in spare time for the last 20 years, when it comes to acoustics whatever sounds wrong is probably the way you should do it. Anyway, get off the BBS's and mutilate some wood, you're almost out of time :wink: :wink: ... Steve

I got a few extra days -- the other remodeling is running a bit behind, but I am still under the gun. I finished the window covers and bought the wood for the resonators today and I start construction on them in earnest tomorrow. Right now I've got a big ol' pile of 703 in my front yard under a tarp - it will be nice to see more of that used up! Of course, if I lived up by YOU steve, I'd have to have a lot more water protection for the 703! <grin> (btw, you'd know if I was ever upset - I *like* clowning around ;) ) Thanks again everyone, this is rocking. What a great example of working together! -lee-

Lee - Direct quote from the 700 series brochure - "All 700 Series Insulation products are dimensionally stable and will not shrink or warp. Composed of inorganic glass fibers, 700 Series Insulation will not rot or mildew and is noncorrosive to steel, copper and aluminum." - Sooo, like, you want to send any leftovers, just tell the FedEx dood to leave them in the front yard... 8)

"All 700 Series Insulation products are dimensionally stable and will not shrink or warp. Composed of inorganic glass fibers, 700 Series Insulation will not rot or mildew and is noncorrosive to steel, copper and aluminum." - sure but if it gets wet it's a bugger to dry out!!!! :):) cheers john