GM, no.. much different to that. A soundwave is not the same as an object moving through a fluid, it is not static flow. In any case, the goals are different.
Jim, Patrick showed that a wavefront can be allowed to widen with a complementary curvature where in other cases it might remain more narrow.
Jim, Patrick showed that a wavefront can be allowed to widen with a complementary curvature where in other cases it might remain more narrow.
Think of how much research B&W put into this. And we see it in the KEF Blades, and of course the Vivids.
And then look at the most aerodtnamic cars/vehicles.
dave
Sorry, not 'seeing' it, but from a purely technical POV not knowledgeable enough to do other than 'agree to disagree' based on non/minimal mathematical published [air] [sea] ship aero/fluid dynamics, sound propagation docs.
It is an involved topic that will hardly fit into a post. The above examples involve disturbances normal to the direction of travel. A speaker is neither moving toward the listener nor the sound moving away from the listener. In fact, the direction of sound changes as it goes, hopefully because we intended it to and the shape of the cabinet needs to change with it.
In any case audible sound is not a flow of air, but a pressure wave. Particles have an alternating, but zero net velocity.
In any case audible sound is not a flow of air, but a pressure wave. Particles have an alternating, but zero net velocity.
Well, in car HiFi maybe . But this indeed is all about how a pressure wave propagates along a boundary. Particle velocity typically is low, your main concerns are avoiding diffraction and keeping the local sound pressure level low enough so that linearity of the system isn't compromised (horn throats).
. But this indeed is all about how a pressure wave propagates along a boundary. Particle velocity typically is low, your main concerns are avoiding diffraction and keeping the local sound pressure level low enough so that linearity of the system isn't compromised (horn throats).
You seem to have a well equipped shop and while your tests will be interesting, I'm stuck on your statement about being easier to veneer. Why veneer a roundover, or your bevels, as opposed to using solid wood? With a reasonable width, and proper orientation, isn't going to have enough movement to stress joints. Just curious ...
I have always wondered how much "diffraction of sound waves" is analogous to "aerodynamic eddies". The way I think of it is that, in the moment that a transducer travels outward, there is air pressure in front of it. Thag air under pressure bumps into the next air and so forth. IOW, a compressional wave has air movement. As that air molecule drags across an edge, eddies cause the air to move in other directions, producing a new compressional wave from that point in all directions, like a tiny little tweeter. Thinking about this way, it seems that for a monopole, a teardrop would be superior to a sphere, because the flow of air around the rear would be smoother. For a dipole, you'd want a large roundover on the sides so that air could pass from front to back without snags. (This was verified by the BG 75 experiments they did in a gym a few decades ago,, wish I had a link handy). I'm assuming that my way of understanding it is not correct. Or am I right?
Could a front baffle with sharp 90 deg corners, but with the tweeter/full range driver significantly off center and distance from each edge radically different ( perhaps in the ratio 1,2,3,4), be as good as a fully rounded baffle, but with all the edge equidistant from the tweeter?
Or would this just be reducing a problem, instead of curing it?
Or would this just be reducing a problem, instead of curing it?
Although it is possible that aerodynamic (low drag) shapes might also be acoustically low diffraction shapes, the physics involved are so different that this similarity is really just coincidence. The analogy is very limited. I am speaking as an aerospace engineer.
An example of an aero shape being different from an acoustical shape is a convergent/divergent rocket nozzle... it may superficially look like a horn or waveguide, the actual shape is very different. This demonstrates the limit of the analogy
Correct.
Sound is a wave phenomenon. The air particles are not moving across the shape, except for the minute microscopic motion caused by the tiny pressure variations that we call sound.
These are very handy and if available locally I would use it.These are 2" round corners I have used set to work with 3/4" material. They are easy to use and make for a very still baffle.
Rob
If painting it’s good, but If veneering, large round-overs it still leaves one with the same issues of finishing the cabinet.
Still harder than a cabinet with square or faceted edges; at the backyard/hobbyist level.
For serialised production of MDF based cabinets most small volume cabinet makers prefer to deal with pre-veneered MDF, and thus mitred joints.
Any true low diffraction cabinet seems to be very labour intensive. Eg. B&W or Vivid cabinet and/or need CNC…
I understand that the air movement is minute and microscopic, yet movement nonetheless. But if the physics is different, then I guess that settles it. Thank you very much for sharing your expertise. Craig
It can replace one problem with another
https://www.prosoundtraining.com/2013/01/25/tweeter-placement-two-way-loudspeakers/