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Multi-Way Conventional loudspeakers with crossovers

how much cabinet sound
how much cabinet sound
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Old 15th November 2013, 06:33 PM   #1
lilun is offline lilun
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Default how much cabinet sound

just how much sound really comes out of the speaker cabinet? Its impossible to tell because you can't listen to it and the sound from the driver separately.

some folks have even said that the sound from the cabinet is many times that of the drive unit. But I can't hear any sound if I listen to the speakers cabinet from behind. In fact even if i put my ear up against the cabinet of my mdf speaker, there is only a faint sound coming through. Is it all lies?

The only good way to tell is to make two identical speakers except one made from a different material to the other. Has anybody done it?
Comparing lets say concrete vs mdf?

And how much mass would the cabinet have to have to dampen out or resist the transferred vibration from the drive unit to the cabinet?
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Old 15th November 2013, 06:42 PM   #2
sippy is offline sippy  United Kingdom
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Several people on this board have listened to enclosures from plywood and mdf made to the same dimensions - usually to settle arguments or whatevers over which material is best.
None of which (threads) seem to be settled one side or other.
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Old 15th November 2013, 06:53 PM   #3
jplesset is offline jplesset  United States
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I think there's some mis-interpretation about "cabinet sound". If you go back to the Linkwitz article from the '70s, he used a phono cart placed in contact with the cabinet to find that at _some_ frequencies, the cabinet was indeed louder than the driver, due to panel resonances. Not _all_ frequencies.

He went further, and explored damping and decoupling the drivers to reduce this output...
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Old 15th November 2013, 10:01 PM   #4
Colin is offline Colin  United Kingdom
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It was also extensively researched by the BBC in the mid 70s. The Linkwitz piece was in Wireless World in 1978 or '79 and I think it's on his site. The BBC papers are on their website in the engineering archive.

http://downloads.bbc.co.uk/rd/pubs/reports/1977-03.pdf

http://downloads.bbc.co.uk/rd/pubs/reports/1988-14.pdf
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Old 15th November 2013, 10:07 PM   #5
jplesset is offline jplesset  United States
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Yes, and yes, it's on Linkwitz' site: SB1980-3way
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Old 15th November 2013, 10:41 PM   #6
Richard Ellis is offline Richard Ellis  Argentina
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My take on the subject....If you can feel the vibrations in the enclosure, no doubt it is producing sound...how much? I don't know. I'm sure someone out there has some data on such an experiment.
Now, run a frequency sweep on an enclosure & I'm sure the thing will sing like a little birdie...
I'm sure one could build an enclosure out of a Lead alloy that won't be set in motion by a driver......but more than a bit impractical.
Myself I'm experimenting with a local "Ironwood" Schinopsis balansae ....at a specific gravity of 1.24 and a Modulus of Rupture of 141.7 MPa (MegaPascals)..tough stuff. I found a local Furniture/Workshop who specializes in the working of the stuff. I should ask just how much it might be to create an enclosure, I've an idea how best to do it.. I think we need to make more "massive" enclosures to rectify this 'thorn-in-the-side' shortcoming.


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Old 15th November 2013, 10:45 PM   #7
Joachim Gerhard is offline Joachim Gerhard  Germany
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One simple possibility is to put the speakers face to face and reverse one in polarity, then playing a mono track.
It works well in the bass and lower midrange but not higher up because it is hard to phase
align the tweeters.
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Old 15th November 2013, 11:10 PM   #8
GM is offline GM  United States
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Quote:
Originally Posted by lilun View Post
just how much sound really comes out of the speaker cabinet? Its impossible to tell because you can't listen to it and the sound from the driver separately.
Impossible? Art Ludwig's research might change your mind: Loudspeaker construction

The rest of his site is equally enlightening to the neophyte, but seems largely forgotten today: Art Ludwig's Sound Page

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Old 15th November 2013, 11:13 PM   #9
Bon is offline Bon  Australia
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Quote:
Originally Posted by Colin View Post
It was also extensively researched by the BBC in the mid 70s. The Linkwitz piece was in Wireless World in 1978 or '79 and I think it's on his site. The BBC papers are on their website in the engineering archive.

http://downloads.bbc.co.uk/rd/pubs/reports/1977-03.pdf

http://downloads.bbc.co.uk/rd/pubs/reports/1988-14.pdf
Also in :
BACKMAN, JUHA: Effect of panel damping on loudspeaker enclosure vibration, Preprint AES 101st Convention 1996 November 8-11 Los Angeles, California.
TAPPAN, PETERW.: LoudspeakerEnclosureWalls. Journal of the Audio Engineering Society, July
1962, reprinted in the AES Anthology Loudspeakers, vol. 1, pp. 88 -- 95, Audio Engineering Society, New York, 1978.
IVERSON,JAMES K.: The Theory of Loudspeaker Cabinet Resonances. Journal of the Audio EngineeringSociety, April 1973, reprinted in the AES Anthology Loudspeakers,vol. 1, pp. 312 -- 315, Audio Engineering Society, New York, 1978

Backman compares 9 test cabinets of different wall materials but otherwise identical constructions and measures the frequency responses as well as the cabinet vibration responses. The comparisons make interesting reading. My interpretation of the results are that the common materials mdf, plywood, particle board are all pretty poor on their own, but surprisingly particle board has some measurable acoustic advantages despite mechanical problems of fragility, moisture attack etc. All of these are improved by various damping methods. Veneer does nothing for damping. Lead is nowhere near as good as reputed elsewhere. Visco-elastic layers (CLD) made significant measured improvements to plywood.
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Old 15th November 2013, 11:25 PM   #10
lilun is offline lilun
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Quote:
Originally Posted by Bon View Post
Also in :
BACKMAN, JUHA: Effect of panel damping on loudspeaker enclosure vibration, Preprint AES 101st Convention 1996 November 8-11 Los Angeles, California.
TAPPAN, PETERW.: LoudspeakerEnclosureWalls. Journal of the Audio Engineering Society, July
1962, reprinted in the AES Anthology Loudspeakers, vol. 1, pp. 88 -- 95, Audio Engineering Society, New York, 1978.
IVERSON,JAMES K.: The Theory of Loudspeaker Cabinet Resonances. Journal of the Audio EngineeringSociety, April 1973, reprinted in the AES Anthology Loudspeakers,vol. 1, pp. 312 -- 315, Audio Engineering Society, New York, 1978

Backman compares 9 test cabinets of different wall materials but otherwise identical constructions and measures the frequency responses as well as the cabinet vibration responses. The comparisons make interesting reading. My interpretation of the results are that the common materials mdf, plywood, particle board are all pretty poor on their own, but surprisingly particle board has some measurable acoustic advantages despite mechanical problems of fragility, moisture attack etc. All of these are improved by various damping methods. Veneer does nothing for damping. Lead is nowhere near as good as reputed elsewhere. Visco-elastic layers (CLD) made significant measured improvements to plywood.
and marble? or aluminium?
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