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PostPosted: May 24th, 2020, 10:21 am 
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Joined: February 28th, 2013, 3:31 pm
Posts: 277
Synergistic Research does sell tiny cups as Paul described. I think Kemper has some.


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PostPosted: May 24th, 2020, 11:29 am 
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Joined: July 24th, 2015, 4:17 pm
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Location: Parkville, Maryland
Just for grins I put together the following:

Approximate Wavelength of Audio Frequencies in Air:

20,000-Hz. approx. = 5/8-inch

15,000-Hz. approx. = 1-inch

10,000-Hz. approx. = 1-3/8-inch

8,000-Hz. approx. = 1-11/16-inch

5,000-Hz. approx. = 2-11/16-inches

3,000-Hz. approx. = 4-1/2-inches

2,000-Hz. approx. = 6-3/4-inches (1/2-foot)

800-Hz. approx. = 16-7/8-inches (1-1/3-foot)

400-Hz. approx. = 33-3/4-inches (2-3/4-feet)

100-Hz. approx. = 135-inches (11-1/4-feet)

50-Hz. approx. = 270-inches (22-1/2-feet)

30-Hz. approx. = 450-inches (37-1/2-feet)

20-Hz. approx. = 675-inches (56-1/4-feet)

Or - to put it perspective - we strive to eliminate unwanted resonances and distortions in our quest for good sound reproduction - why on earth would we even consider such device such as resonating bells and hollow metal cups?! :confusion-confused: I'm cornfused.

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PostPosted: May 24th, 2020, 11:51 am 
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Joined: July 17th, 2016, 6:24 am
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Walt,

What are you driving at by posting the wavelength chart?

Resonance frequency is not dependent upon the diameter of the resonating medium being equal to the wavelength. You don’t need 56’ drum to generate 20Hz sound wave.

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PostPosted: May 24th, 2020, 11:57 am 
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Cogito wrote:
Walt,

What are you driving at by posting the wavelength chart?

Resonance frequency is not on the diameter of the resonating medium. You don’t need 56’ drum to generate 20Hz sound wave.


If anyone can find out what frequency these gizmos resonant at they'll have an idea what effect they can have on the sound. As I said, we strive to eliminate unwanted resonances and distortions in our quest for good sound reproduction - why on earth would we even consider such device such as resonating bells and hollow metal cups?! :confusion-confused: I'm cornfused.

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Walt


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PostPosted: May 24th, 2020, 12:45 pm 
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SoundMods wrote:
Cogito wrote:
Walt,

What are you driving at by posting the wavelength chart?

Resonance frequency is not on the diameter of the resonating medium. You don’t need 56’ drum to generate 20Hz sound wave.


If anyone can find out what frequency these gizmos resonant at they'll have an idea what effect they can have on the sound. As I said, we strive to eliminate unwanted resonances and distortions in our quest for good sound reproduction - why on earth would we even consider such device such as resonating bells and hollow metal cups?! :confusion-confused: I'm cornfused.


Helmholtz resonators can be used to tame peaks in sub-bass frequencies.

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PostPosted: May 24th, 2020, 2:05 pm 
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Joined: January 15th, 2015, 7:19 am
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Location: Baltimore MD
Talk to Paul McGowen about Hemhilts Resonators on how uneffective they were when he built his first sound room for his RS-whatevers


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PostPosted: May 24th, 2020, 6:40 pm 
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Came across this video.

https://youtu.be/Ck-fZJvf39M

Paul is using huge Helmholtz resonator to dissipate bass energy. My goal is to use the phase reversed energy yo cancel some of the energy at peaks, about 8-10dB. Small portable resonators will get the job done.

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PostPosted: May 24th, 2020, 6:46 pm 
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Joined: January 15th, 2015, 7:19 am
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Location: Baltimore MD
Good luck


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 Post subject: Portable Resonators
PostPosted: May 25th, 2020, 9:04 am 
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http://www.acusticaapplicata.com/polifemo.php?lang=eng

Attachment:
C3B431F7-C4DF-47AF-BDCD-B2E5A78CED7A.jpeg
C3B431F7-C4DF-47AF-BDCD-B2E5A78CED7A.jpeg [ 35.7 KiB | Viewed 712 times ]

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PostPosted: May 25th, 2020, 10:07 am 
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Joined: January 15th, 2015, 7:19 am
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Location: Baltimore MD
whatever floats your boat... man
Get a sonotube and mount an old woofer


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