How is working Awaphon, please. Is it about to add weigth to the structure to lower the resonnance ?
Edit : okay found it : it works by thermal dissipation behavior. Seems a clever stuff, but just wonder of the weigth added. We want stiff but not heavy for the bass cabinet.
I liked your idea of the aluminium sheet in the OSMC paper !
Edit : okay found it : it works by thermal dissipation behavior. Seems a clever stuff, but just wonder of the weigth added. We want stiff but not heavy for the bass cabinet.
I liked your idea of the aluminium sheet in the OSMC paper !
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It can down in frequency rhe résonance for the bass cabinet.
For the mid this is at the opposit what we want. (We 'de like to put the résonance above in the mid where it is harmless or ideally above the filter cut off in theory.
But it is hard to make stiff with wood without weigth. Bitum pads are contreversal because of the weigth added.
The Awaphon doc seems to say it works from the midrange.
For the mid this is at the opposit what we want. (We 'de like to put the résonance above in the mid where it is harmless or ideally above the filter cut off in theory.
But it is hard to make stiff with wood without weigth. Bitum pads are contreversal because of the weigth added.
The Awaphon doc seems to say it works from the midrange.
Hawaphon consists of an array of cells filled with metal beads. Vibrational energy is converted to heat by friction of the beads relative to each other.
The speed of sound in wood is somewhere around 3...5 km/s. The wave lengths at different frequencies are therefore:
100 Hz: 30...50 m
300 Hz: 10...17 m
1 kHz: 3...5 m
3 kHz: 1...1.7 m
10 kHz: 30...50 cm
As you can see, frequencies of 1 kHz or lower can hardly develop a resonance in the panels of the OSCM box, because the panels are too small to resonate at these frequencies. No need to worry about bass resonances in the panels.
The speed of sound in wood is somewhere around 3...5 km/s. The wave lengths at different frequencies are therefore:
100 Hz: 30...50 m
300 Hz: 10...17 m
1 kHz: 3...5 m
3 kHz: 1...1.7 m
10 kHz: 30...50 cm
As you can see, frequencies of 1 kHz or lower can hardly develop a resonance in the panels of the OSCM box, because the panels are too small to resonate at these frequencies. No need to worry about bass resonances in the panels.
Do they not résonate because of pressure and internal modes? So no worth bracing because it is too small ? Can use also 0.5 mm width wood ?
I missed the point of your input.
But anyway it is a liitle off topic.
Thanks for the Awaphon ref. Gave me the envy to try in a mid driver cabinet.
I missed the point of your input.
But anyway it is a liitle off topic.
Thanks for the Awaphon ref. Gave me the envy to try in a mid driver cabinet.
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Your experience could show the way in this case.. but technically, small panels can resonate at lower frequencies. It’s just a matter of adding enough mass to them, not a matter of their size.
Whether you try for light and stiff, or heavy and loose, the one thing that always has the potential to help if it’s needed, is damping.
And for damping in the lows, adding stiffness is the targett if I understood. (With bracing instead adding stifness by widther wood that increase the weigth) . A way to loose some energy is bracing constraint layer damping to decouple the surface without giving up stifness added by the bracing. To do so the bracing must be made constraint layer damping, which is a mess and I surmise not needed for the not big OSMC.
We only talked of the 12" driver as the dome mid is already sealed. The OSMC doen t need Awaphon, it is not in the pdf description iirc, btw.
Rigth?
Cheers.
We only talked of the 12" driver as the dome mid is already sealed. The OSMC doen t need Awaphon, it is not in the pdf description iirc, btw.
Rigth?
Cheers.
So why then the heavy bracing of subwoofers? Why do others bother with complicated enclosures that avoid standing waves?
Probably not for avoid resonances primarily but for reduce panel flexing, these are different things.
I was speaking about wood panels, not composite materials.
Adding a layer of Hawaphon to a wooden panel won't change the speed of sound propagation in a meaningful way, so my argument stands.
Are you referring to standing waves in the wood panels, or in the air volume inside the box? Bracing is used to make the panels more rigid. It will not change things for the air in the box.
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If for any reason the panel finds itself away from it's resting position, for example due to the zeroth mode (breathing mode) which is one of the targets of standard cross bracing.. a restoring force will be exerted in addition to the others. It will apply according to a resonance formed by the mass of the panel and it's compliance.
Yes, and the frequency and wavelength of that resonance will be as calculated in my post #1745. With the same conclusion as in post #1745.
Not sure why you'd think so. The speed of sound in the panel is determined by the stiffness and density of the panel material. This is what controls the ratio of the resonance frequencies and their wavelengths.
Gradient of what?
[We're wandering off topic -- the mods can always move this discussion to a separate thread if they think that makes sense.]
Far out.... What a beautiful workbench! Definitely looks like an artisan's shop. But, 2X scroll saws? That looks more professional factory.
and sorry mbrennwa, to keep on OSMC topic, such a great resource. Thanks to those that did the heavy lifting of this thread.
The pressure distribution across the panel, which ought to be fairly uniform with the fundamental resonance so the only input from the high speed of sound in the panel might be helping to keep the resonance clean, and this should get easier as the frequency goes down.
I have posts on this thread so I keep out of the process.
Just to play "The Devil's Advocate" >
The old Spendor speakers ( a BBC reference at the time ) intentionally used cabinet resonance to 'add' to the sound 😕
This has now obviously been recognized as a very poor way to design a speaker.
But just think about how long the Spendors were highly acclaimed 😎
PS.
In my "Twin Tower" design speakers, I use 2 slabs of concrete for weight, rigidity & stability.
The old Spendor speakers ( a BBC reference at the time ) intentionally used cabinet resonance to 'add' to the sound 😕
This has now obviously been recognized as a very poor way to design a speaker.
But just think about how long the Spendors were highly acclaimed 😎
PS.
In my "Twin Tower" design speakers, I use 2 slabs of concrete for weight, rigidity & stability.
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I am still not sure I get your point. Are you referring to air pressure? Again, I am not talking about acoustic waves in air. I simply considered the propagation of sound waves in the panel material, and worked out the frequency range of potential resonances of the panel. This shows that standing waves (resonances) cannot occur in the panels at bass frequencies.