Hi everyone,
I am exploring alternatives to traditional sound-absorbing materials (foams, fibers, and pyramidal diffusers) for the treatment of reflections, standing waves, and harmonics inside loudspeakers. In particular, I am focusing on the use of thin membranes, placed on the internal walls, to absorb specific unwanted frequencies.
The idea is to use flexible panels composed of a thin film coupled with layers of neoprene or rubber to create membrane resonators and reduce problems in the low frequencies. Some points I would like to discuss with you:
1️) Materials and Structure: What materials have you successfully tested for these applications? Are there particular combinations that improve the effectiveness of absorption?
2️) Positioning: Is it more effective to place the membranes on all the internal walls or just on some strategic areas? Are rigid panels better or with a minimum of flexibility?
3️) Thickness and Mass: How does the mass of the membrane affect the resonance frequency? For example, do two membranes with different areas but the same mass behave differently?
4️) Overlap and Spacing: Is it possible to overlap multiple membranes leaving an air gap between them? If so, is it useful to tune them to slightly different frequencies for a wider action?
5️) Alternatives to Helmholtz Resonators: In which cases can membranes replace or integrate Helmholtz resonators?
Does anyone have experience or practical tests on this technique? I would like to collect ideas, experiments and maybe compare some simulations. Thanks to anyone who wants to share their know-how!
I am exploring alternatives to traditional sound-absorbing materials (foams, fibers, and pyramidal diffusers) for the treatment of reflections, standing waves, and harmonics inside loudspeakers. In particular, I am focusing on the use of thin membranes, placed on the internal walls, to absorb specific unwanted frequencies.
The idea is to use flexible panels composed of a thin film coupled with layers of neoprene or rubber to create membrane resonators and reduce problems in the low frequencies. Some points I would like to discuss with you:
1️) Materials and Structure: What materials have you successfully tested for these applications? Are there particular combinations that improve the effectiveness of absorption?
2️) Positioning: Is it more effective to place the membranes on all the internal walls or just on some strategic areas? Are rigid panels better or with a minimum of flexibility?
3️) Thickness and Mass: How does the mass of the membrane affect the resonance frequency? For example, do two membranes with different areas but the same mass behave differently?
4️) Overlap and Spacing: Is it possible to overlap multiple membranes leaving an air gap between them? If so, is it useful to tune them to slightly different frequencies for a wider action?
5️) Alternatives to Helmholtz Resonators: In which cases can membranes replace or integrate Helmholtz resonators?
Does anyone have experience or practical tests on this technique? I would like to collect ideas, experiments and maybe compare some simulations. Thanks to anyone who wants to share their know-how!
Just a quick question how are you going to de-couple the panels from the enclosure? If you don't de-couple wouldn't the resonating panels couple with/too the cabinet and make matters worse? These will be tuned and be resonant to some specific frequency? Why not just use standard absorption like fiberglass that is inert.
Rob 🙂
Rob 🙂
Hi,
yes it seems complicated solution for non-issue, so haven't stumbed on this kinda stuff inside loudspeakers. Resonances inside the box relate to box dimension wavelengths so it's not really bass. Bass is mostly room sized or bigger wavelenghts and typical loudspeakers are midrange frequency wavelength sized where wadding is still effective. Resonators are common in room bass management though, which woudl require squaremeters worth of wadding, due to very long wavelengths.
Perhaps on some kind of a speaker system such resonator would help. There is wealth of information on the web about resonators.
yes it seems complicated solution for non-issue, so haven't stumbed on this kinda stuff inside loudspeakers. Resonances inside the box relate to box dimension wavelengths so it's not really bass. Bass is mostly room sized or bigger wavelenghts and typical loudspeakers are midrange frequency wavelength sized where wadding is still effective. Resonators are common in room bass management though, which woudl require squaremeters worth of wadding, due to very long wavelengths.
Perhaps on some kind of a speaker system such resonator would help. There is wealth of information on the web about resonators.
If you want a type of "black hole damping" try the following.
Get carpet for floors with rubber. If you put 3 to 5 of them as layers on all sides in the box. Its pretty dead.
Get carpet for floors with rubber. If you put 3 to 5 of them as layers on all sides in the box. Its pretty dead.
I don't know if I understood your question correctly.
by decoupling do you mean what precaution to use to avoid transmitting the membrane vibrations to the container wall ?
Greets!
At a glance it seems reasonable to me, but an easier way me n' some others were doing nearly 60 yrs ago was suspending a vertical panel diagonally across the cab as a variation of the Bozak Concert Grand's suspended 'blanket' that Altec recommended in its '74 DIY Cab design manual pg. 8 and later reappears as a ~wall height panel size bass traps.
At a glance it seems reasonable to me, but an easier way me n' some others were doing nearly 60 yrs ago was suspending a vertical panel diagonally across the cab as a variation of the Bozak Concert Grand's suspended 'blanket' that Altec recommended in its '74 DIY Cab design manual pg. 8 and later reappears as a ~wall height panel size bass traps.
Here's a great article referenced many times in audio ESP box filling. My REW measurements support this article too. I find it helps smooth out the 400-crossover range.
Another goofy Idea was to used large open cell foamed aluminum But I've not gotten around to trying that.
Another goofy Idea was to used large open cell foamed aluminum But I've not gotten around to trying that.