A local forum member (Koen K, around here too) designed this:
Courtesy to him of course, but I think this kind of design is both aesthetically and acoustically appealing.
Nice! I really like the 'deep dish' waveguide and if that's a Bliesma, oh man do I want one-
Actually a shallow box can have the advantage of shifting the reflections of some of the internal waves up in frequency and make them easier to absorb.
I'm hashing out concepts for wide/shallow and I gotta say, the possibilities are much more readily available when it comes to managing the surfaces. If internal waves are manageable, then all the more appealing this option is looking. Will have some concepts drafted up for preview today-
That ripple sim made me a little queasy btw. Too bad you can drop a cross section of a baffle in that baby-
I'm not sure I understand, are you saying you didn't find how to create obstacles? Yes, it makes my eyes go funny after a while. 🙂
Whoa, yeah I didn't see that you can add shapes earlier. I notice that the edges of of box will diffract based on frequency. Very cool, will experiment more-
The greater the time delay of the diffraction the more noticable it will be.
dave
Would that imply that a small baffle footprint will be less noticeable because the edge distances are more near the source? It seems like if you have a large surface baffle, that is a case for having better diffraction control, due to greater delay, if I'm understanding correctly. Either way, it would be good news for both form-factors. Wide baffle gives much freedom/space to gently guide the surface. Small footprint is harder to manage the transitions, but there should be less delay, therefore less noticeable.
How about a roundover with a continuously varying radius... parabolic... a thumbnail bit?
Very handy. Was planning to make the baffle from aluminum and a profiled cutter for metal is a bit hard to come by unfortunately. One that's affordable that is.
Would that imply that a small baffle footprint will be less noticeable because the edge distances are more near the source?
Everything is a compromise. A narrower baffle wil have HF diffractions earlier so they will tend to be less noticable, but it also moves the 2pi to 4pi transition up in frequency where we ar emore sensitive to it.and depending on the shape of the box you have iripple in the FR that can be more of a problem.

dave
The shape works. The needed dimensions of the edges are related to the bandwidth of the driver.
Same shape for the tweeter pod on these from decades ago. A crude approximation of a teardrop.
In many speakers you only really need to worry about the vertical edges.
dave
Same shape for the tweeter pod on these from decades ago. A crude approximation of a teardrop.
In many speakers you only really need to worry about the vertical edges.
An externally hosted image should be here but it was not working when we last tested it.
dave
If the diffraction were only taken care of then we wouldn't be having this conversation. The justification (going back decades now) for having squared edges close to the driver is that commercial manufacturers have found it expensive to sufficiently round the edges, and easier to sell narrow speakers.Would that imply that a small baffle footprint will be less noticeable because the edge distances are more near the source?
Wouldn't it also make them stronger?scottjoplin said:A narrow baffle places the secondary sources close to the driver, horizontally at least, which mitigates the negative effect on imaging to a degree.
I'd think imaging would suffer as a result of the close "secondary" sources. A bit like a diffraction slot in a older style horn increasing group delay and smearing the image.
The shape works. The needed dimensions of the edges are related to the bandwidth of the driver.
In many speakers you only really need to worry about the vertical edges.
dave
I'm liking that TAD setup, the way they do the sides. Enough bracing to park a tank on too.
I'd think imaging would suffer as a result of the close "secondary" sources. A bit like a diffraction slot in a older style horn increasing group delay and smearing the image.
Good point about the horn issue, and to me, I'd think that there would be issues right at the edge of the speaker basket and the baffle.
If the diffraction were only taken care of then we wouldn't be having this conversation. The justification (going back decades now) for having squared edges close to the driver is that commercial manufacturers have found it expensive to sufficiently round the edges, and easier to sell narrow speakers.
Wouldn't it also make them stronger?
In that case is it safe to assume you favor the larger and more smoothly transitioned geometries? Small/narrow is because cheap/easy, if I understood you correctly.
This makes me wonder why the high-end bookshelf speakers don't do a more wide/shallow approach. They basically are just scaled down or truncated versions of regular cabs, which, of course, don't usually have large surface baffles.
Based on planet10's example of wide baffle, I am working on a scaled down version for the now 22 liter 2-way. Here's where I'm at on it-
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Wouldn't it also make them stronger?
My understanding is that the timing and the distance are more important.
Intensity is important. Intensity decreases with distance from the source, or more accurately they are spread out more (assumming an approx circular source).
dave
dave
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