Possibly.
The path to the rest of the bass enclosure is straighter, so that's a theoretical benefit.
A radial brace layout using solid ribs looks feasible also (like the Gekko unit you referenced previously).
The path to the rest of the bass enclosure is straighter, so that's a theoretical benefit.
A radial brace layout using solid ribs looks feasible also (like the Gekko unit you referenced previously).
Is it true that passive radiators acts like a port under the resonance frequency, but as a closed cabinet above ?
Sort of, but if you want to make that kind of argument I would lean toward something like "under the range around the resonance frequency" or "for frequencies less than about 2x resonance" instead of "under the resonance frequency."
And if you want to make that argument for passive radiators, I think you would have to say the same thing about vented/ported cabinets also. Generally, once you are significantly above the resonance of the enclosure, most designs have similar excursion and group delay performance, whether sealed, ported, or passive radiator. Of course there are many ways to tune things and many other ways to introduce errors, so none of this is guaranteed for all configurations.
From the Loudspeaker Design Cookbook by Dickason: "Passive-radiators (PR) are a type of vent substitute, and closely follow vented loudspeaker design methodology and performance characteristics. . . . On the downside, PRs have a steeper cut-off (and less transient stability), a slightly higher cut-off frequency and greater overall losses (QL) than vented designs. . . . Working as a vent, PRs only add as much as they subtract. This implies they have the same positive attributes as a vent, such as higher power handling and lower distortion."
And if you want to make that argument for passive radiators, I think you would have to say the same thing about vented/ported cabinets also. Generally, once you are significantly above the resonance of the enclosure, most designs have similar excursion and group delay performance, whether sealed, ported, or passive radiator. Of course there are many ways to tune things and many other ways to introduce errors, so none of this is guaranteed for all configurations.
From the Loudspeaker Design Cookbook by Dickason: "Passive-radiators (PR) are a type of vent substitute, and closely follow vented loudspeaker design methodology and performance characteristics. . . . On the downside, PRs have a steeper cut-off (and less transient stability), a slightly higher cut-off frequency and greater overall losses (QL) than vented designs. . . . Working as a vent, PRs only add as much as they subtract. This implies they have the same positive attributes as a vent, such as higher power handling and lower distortion."
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Is Black MDF bad for speaker building ? I wonder if black MDF that is aesthetically nice, is different from uncolored MDF ?
I've seen it used, but don't have direct experience with it. I wouldn't expect the dye to be a significant portion of the mix, so overall acoustic performance should be the same as uncolored. This supplier says, "Retains the physical properties and characteristics of conventional MDF panels," and is apparently offering a gloss finish now, but I'm not sure how hard it is to find.
http://packardforestproducts.com/products/wood-composites/spectratech-color-mdf/
The stuff I've seen previously had a flat sheen, which would require clear coating or some other finish application for a cosmetic panel. Here's one thread where that kind was used. There are some closeups and images lit with sunlight where you get a better feel for the surface finish.
https://www.diyaudio.com/community/threads/paper-sandwich-ribbon.352342/#post-6157185
http://packardforestproducts.com/products/wood-composites/spectratech-color-mdf/
The stuff I've seen previously had a flat sheen, which would require clear coating or some other finish application for a cosmetic panel. Here's one thread where that kind was used. There are some closeups and images lit with sunlight where you get a better feel for the surface finish.
https://www.diyaudio.com/community/threads/paper-sandwich-ribbon.352342/#post-6157185
Thanks. Troels Gravesen said the same (and he use it all the time), so I will stick with the Black MDF.
Think out of the box, literally. Flat stuff is the worst for containing pressure because it has abysmal stiffness. No pressure vessel has straight walls, nor do cars have flat bodywork. By compound curving the back panel, it could be made from a couple of millimeters of laminate.
Ok. Thanks. But then you could argue that a circular speaker would be ideal, which I guess is not the case ?
In many cases, I think it's ease/speed of manufacture. For a CNC, large rounded inside corners are the easiest to make. You can use a single larger cutter, which lets you move faster and remove more material. It also lets you maintain more continuous motion, instead of needing to pause for a direction change like you would need to make a sharper corner.
From an engineering standpoint, rounded corners minimize stress concentration. For something like a ship or airplane, this becomes more important. For a speaker box not as much of a concern.
A rounded corner can emulate a corner brace though, so there is some benefit in that regard.
The Lyngdorf fr-1 is very similar in concept, might be able to get some construction ideas from that.
The most impressive wall mounted speakers in terms of inertness I have seen, have been the Steinway Lyngdorf s-15, they are made out of aluminum, the back of the speaker is probably around 6-9mm thick.
The most impressive wall mounted speakers in terms of inertness I have seen, have been the Steinway Lyngdorf s-15, they are made out of aluminum, the back of the speaker is probably around 6-9mm thick.
It'll be a lot better than where you started, but the large free spans at the perimeter look less than ideal. How much "less" is hard to predict without building it. More bracing is "always" better, but there are diminishing returns.
You could also do a brace layout like this using solid ribs. Same number of ribs, but smaller free spans and a little more breathing room around the drivers to help with the solid braces.
You could also do a brace layout like this using solid ribs. Same number of ribs, but smaller free spans and a little more breathing room around the drivers to help with the solid braces.
Thanks, Mattstat. I actually considered that too, and I see now that it is a better idea. How much beathing room against the frame ?
It is funny how you see new things, once you actually start assembling things (oh, I could mount the woofer/radiators from the backside etc)
It is funny how you see new things, once you actually start assembling things (oh, I could mount the woofer/radiators from the backside etc)
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I'm not sure which frame you're referring to.
Speaker or passive radiator frame - keeping the ribs 1-2 inches from their mounting holes should be OK.
If you were asking about the outer perimeter of the enclosure - there you can run the ribs all the way out and glue them to the side wall if you want.
One of the benefits of building early prototypes is that more serendipitous realizations can happen. If you have high standards, it really is hard to plan everything perfectly without building and measuring some things along the way.
Speaker or passive radiator frame - keeping the ribs 1-2 inches from their mounting holes should be OK.
If you were asking about the outer perimeter of the enclosure - there you can run the ribs all the way out and glue them to the side wall if you want.
One of the benefits of building early prototypes is that more serendipitous realizations can happen. If you have high standards, it really is hard to plan everything perfectly without building and measuring some things along the way.
Based on what - Aesthetics or acoustics? 2” will to a large extent limit your choice of drivers to dinky full range types