I have more faith in this 🙂: https://en.wikipedia.org/wiki/Room_modes
Wikipedia said:
For those who want to try the pyramids there might be an alternativ way to build them. You cut the panels, 'stitch' them together with i.e. copper wire and seal the edges with glassfibre lamination.
Why do you not like over damped boxes, what is wrong with the sound?
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I just have, and I'm thinking the operative word is "porous". A porous absorber is pretty much independent of SPL, but needs depth. A non-porous absorber would be very dependent on SPL, but could be shallow. It would run out of excursion at some point, but below that point would be effective. This may explain the performance of the reference I gave.
As to what material is best for lining a speaker enclosure, well that's an area for discussion...
In a perfect world; the box and driver neither add or take away from the intended signal. Let's compare damping to a car suspension. Too tight or stiff is not good; neither is too loose (or mushy/spongy).... In terms of math and engineering; I am thinking critically damped as preferred to over damped or under damped. Take a transient signal for instance; if it is over damped, the waveform dies down before it is supposed to. If it is under damped; it keeps going after it is supposed to; neither one is accurately representing the true input signal.
I use 3 different types of materials and techniques for 3 different reasons; each has a slightly different role to do in suppressing unwanted reflections, etc.
I do not consider that product serious and the density is all wrong, i would not use this in a loudspeaker box
Damping is about controlling resonance so if it's over damped I don't see how this effects the speaker following the input waveform as it dies down?
I do not think it is accurate to compare with a car suspension, what is a neutral suspension setting? But with an audio signal we can aim for neutral response, which is the flatest and most widebanded frequency and phase response possible, for a box speaker this is a low q closed box
In practical terms, if a sealed enclosure is over-damped, the cone experiences a higher force bringing it back to centre than the voicecoil is pushing it away from center. The movement of the cone at resonance becomes closer to doing nothing at all than following the input signal.
It's subjectively better to have slightly under-damped or critically damped bass, than barely audible bass.
Unless you reach a really high resonant Q (>>1) there is no perceived decay, just a difference in frequency response.
Re: the OP's question; The 'box sound' could be reflections internally which cause peaks/nulls in the midrange frequencies - these can be resolved with stuffing, see: Volume filling a reflex box
Either that or you perceive the increase in bass as 'box sound'. Perhaps you just have a preference for less bass?
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Although I am not a big fan of boomy bass (I usually put some damping in the BR port) I am not bass shy. I don't think it has anything to do with dipole vs. box room interaction etc. .TMM said:
If I play a driver without a box it sounds alive, put it in a box and I think 'what is wrong'. My stiffening and damping experiments didn't go as far as some examples here, therefore I will try to improve it, but I don't have high hopes that I will get the 'real' (unboxed) sound of the driver.
From TMM;
"In practical terms, if a sealed enclosure is over-damped, the cone experiences a higher force bringing it back to centre than the voicecoil is pushing it away from center. "
I think this is just wrong.
A cone experiences a force to move to a given point which compresses the enclosed air, and that compression applies the same force to return the cone to its centre position.
"In practical terms, if a sealed enclosure is over-damped, the cone experiences a higher force bringing it back to centre than the voicecoil is pushing it away from center. "
I think this is just wrong.
A cone experiences a force to move to a given point which compresses the enclosed air, and that compression applies the same force to return the cone to its centre position.
Re: Please define critically damped in this context.
Re: Please define critically damped in this context.
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If the *real world* Qtc= .500 it is considered critically damped.
(I'm other *other* old speaker guy)
Re: Please define critically damped in this context.
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If the *real world* Qtc= .500 it is considered critically damped.
(I'm other *other* old speaker guy)
Haha, yes, thanks. I ask because people's definitions vary, ie, in this thread: https://www.diyaudio.com/forums/multi-way/38623-underdamped-overdamped-2.html#post5306133
old text books
I'm just telling you the way I learned it. Yes, from reading text books on acoustics and speaker design.
I still refer to them from time-to-time.
You know; books by:
Olson, Badmieff & Davis, D.B. Weems, Dickason, Collums, etc.
I'm just telling you the way I learned it. Yes, from reading text books on acoustics and speaker design.
I still refer to them from time-to-time.
You know; books by:
Olson, Badmieff & Davis, D.B. Weems, Dickason, Collums, etc.
More learnin fer y'all
2.1 - Open Baffle (aka Dipole)
The open baffle or dipole speaker is favoured by some, most notably the late Siegfried Linkwitz. An open baffle (or open-backed box) was used from the earliest days of amplified sound, and is by far the easiest to build. Ideally, the baffle should be large compared to wavelength (the 'infinite' baffle), but this is very difficult to achieve at low frequencies. So, while they are easy to build, they are not so easy to design (or even produce) in sizes that suit low frequencies. One wavelength at 100Hz is already 3.43 metres, so the size rapidly gets out of hand.
Loudspeaker Enclosure Design Guidelines
2.1 - Open Baffle (aka Dipole)
The open baffle or dipole speaker is favoured by some, most notably the late Siegfried Linkwitz. An open baffle (or open-backed box) was used from the earliest days of amplified sound, and is by far the easiest to build. Ideally, the baffle should be large compared to wavelength (the 'infinite' baffle), but this is very difficult to achieve at low frequencies. So, while they are easy to build, they are not so easy to design (or even produce) in sizes that suit low frequencies. One wavelength at 100Hz is already 3.43 metres, so the size rapidly gets out of hand.
Loudspeaker Enclosure Design Guidelines
Specifically, since TMM (that's not how he defined it in that thread) responded to a reply to Oldspeakerguy, I'd like to know if they're on the same page.