AVS Forum Special Member
Join Date: Aug 2005
Location: Denver, Colorado
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Looks like I probably won't be able to partner with anyone in Denver for this, so I thought I'd throw out what my plan was for anyone that might be able to go through with the experiment.
I would use a driver like the Peerless 830983 or 830985 due to their wide band response and shorting rings. Make a small box which can be attached to the test enclosure. First take a free air measurement to set the SPL at 90-93 dB or so and give a baseline response. Then attach the box to the front baffle of the test enclosure so it fires into the test box. This way the sound will reflect off the back of the box before going back through the dummy driver, just as if the dummy driver were making the sound. Speaking of that, I was going to use the SB Acoustics 15cm poly cone since it is pretty "typical" and I have the aluminum version on hand also to see how the diaphragm material effects re-radiation.
Now you can test various linings/absorption. I would test denim insulation, open cell foam like flooring backer, acousta stuff, etc. Frequency response, impedance, and possibly harmonic distortion would be of interest.
For the enclosure radiation it would probably be best to use a wood blank in place of the dummy driver. I would build test boxes of: 3/4" mdf, 3/4" mdf doubled up, 3/4" birch ply, 3/4" bamboo laminate, then some CLD methods. Maybe 1/4" mdf with 1/8" sorbothane pad in between. Maybe another with the 3M tape I mentioned. One made of urethane would be cool. Also coating one of the boxes with Acoust-X would be interesting. Certainly changes the "knuckle rap" test when I've used it. Measurements of interest: frequency response, CSD, harmonic distortion, impulse response.