Dowling will help. But these things have got big panels, and should hit some pretty serious LF; ~23Hz would you believe? Nor will SPL be a problem, methinks. The bracing Dave has drawn is heartily encouraged. Bit of a pain to make -not overly difficult, just time consuming. But it'll kill panel resonance stone-dead, and brace the drivers too. Worth it in the long run.
planet10 said:
I do some woodworking and also own a sawzall. I would never attempt to build anything "finished" with the sawzall. It is an awesome tool for cutting holes in walls, slicing through 2x4's, pipes and whatever else is in there but is not suited to fine work, especially small radius curves.
A hole saw (a kind of drill bit) is the tool of choice. Drill half way through and flip the board over. Using the 1/4" pilot hole it drilled finish the hole from the other side. This will eliminate tear out on the surface.
John
John Walker said:
It is, but a swiss cheese brace isn't about finished work. It is hidden in the box and 50% random holes is the goal. I do admit that the hole sawed & champhered cheese holes we do are nice & look very professional.
We have probably thrown down the guantlet, and we soon may see a box made using a recip-swa as the only cutting instrument. Hope he has a big file too
dave
ok, Wide Thor -- I had to make the cabinet a bit shorter -- so it's 1 metre (39.37"), and 30cm wide -- but haven't yet taken into account the volume displaced by the swiss cheese. A little bit squigglier than yours. The cabinets are only partly assembled.
An externally hosted image should be here but it was not working when we last tested it.
i will shamelessly admit that I am using my biscuit cutter to put together the MDF -- this doesn't help the cabinet strength one iota but it sure makes assembly a heck of a lot easier.
one thing about biscuits in the summer -- they swell almost instantly when exposed to the high humidity here in the eastern U.S.
if i were to make the cabinet isoceles-trapezoid-like, (to bevel the front) keeping the same line length (39 or 40 inches), and same top and bottom surface area -- can I assume that the area of the rectangle is just transformed from the area of the trapezus? -- i.e. line length is constant and cabinet volume is constant.
one thing about biscuits in the summer -- they swell almost instantly when exposed to the high humidity here in the eastern U.S.
if i were to make the cabinet isoceles-trapezoid-like, (to bevel the front) keeping the same line length (39 or 40 inches), and same top and bottom surface area -- can I assume that the area of the rectangle is just transformed from the area of the trapezus? -- i.e. line length is constant and cabinet volume is constant.
Well, TLs are known for being good at bass...
The question's more technical and historical than you probably realise. I actually don't like the term TL very much -never have, it's confusing, because it means different things to different people. It's best applied to a Biley / Bradbury line (usually tapered) and very heavily damped.
These are actually MLTLs, or as I prefer to term them, Mass Loaded Quarter Wave Resonators, so rather than feeding into a long, heavily damped line a la Bailey / Bradbury, they are designed to resonate strongly at a design frequency, the excitation being caused by the drivers of course. The Mass Loading is provided by the air-mass in the restricted terminus (i.e the port) which lowers the first cabinet mode and helps supress harmonic resonances. How low you go with these particular beasts will depend on your own room of course, but I'd be astounded if they weren't ~flat to 30Hz, and strong into the low 20s.
The question's more technical and historical than you probably realise. I actually don't like the term TL very much -never have, it's confusing, because it means different things to different people. It's best applied to a Biley / Bradbury line (usually tapered) and very heavily damped.
These are actually MLTLs, or as I prefer to term them, Mass Loaded Quarter Wave Resonators, so rather than feeding into a long, heavily damped line a la Bailey / Bradbury, they are designed to resonate strongly at a design frequency, the excitation being caused by the drivers of course. The Mass Loading is provided by the air-mass in the restricted terminus (i.e the port) which lowers the first cabinet mode and helps supress harmonic resonances. How low you go with these particular beasts will depend on your own room of course, but I'd be astounded if they weren't ~flat to 30Hz, and strong into the low 20s.
too many years doing partial differential equations -- when you were a chem major decades ago you took as much math as the physicists.
here's a rendition of the wide-beveled Thor -- the number of cubes is ~5,700 in^3
here's a rendition of the wide-beveled Thor -- the number of cubes is ~5,700 in^3
An externally hosted image should be here but it was not working when we last tested it.
