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Vb vs Damping and Acoustic Absorption [message #49697] Wed, 12 July 2006 02:46 Go to next message
dB is currently offline  dB
Messages: 234
Registered: May 2009
Master
Hi,
(Wayne, maybe you had a similar situation before?)
I am building this speaker for a 10" and the resonance curve (output) is good for a box with 60L-80L(2.1cf-2.8cf). Now, if I use a good acoustic absorbent about 20mm(3/4") I will lose about 17.5L(0.6cf).

All computed (w/speakers, port and others protusions) I will end with a 35.7L(1.3cf) box what gives a really bad shaped curve. And it's about half the volume of the designed project and not only 10%. If I use an acoustic absorbent from the auto industry (like the one they use under a car) it's a film of about 1L of volume per speaker.

Not the best Damping factor but the Total volume will be about the one that was designed for. What is the best compromise? (Also -- What about the 'expensive' line-X? ...anyone)
Regards

Copopren (CA150-20mm) foam by Recticel: agregated polyurethane foam with an absorption grade of 12dB at 125 Hz, 20dB at 250 Hz, 32dB at 500 Hz, 37dB at 1000 Hz, 60dB at 2000 Hz.


Re: Vb vs Damping and Acoustic Absorption [message #49698 is a reply to message #49697] Wed, 12 July 2006 08:30 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18691
Registered: January 2001
Illuminati (33rd Degree)

One thing that may help you - Acoustic insulation displaces some interior volume, but it has the opposite effect. Adding acoustic insulation tunes the box as if it were larger. Some acoustic simulation programs model this effect, but to know how much adjustment is made is largely an empirical matter.


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