Quote:
Originally Posted by
riprowan
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I used MDF melamine board from a local hardware store because I don't currently have access to a good shop or quality tools with which to build. For damping material I used just a small amount of rockwool. I really had no idea how much to use, but my understanding is that the more absorption you use, the lower the "peak" but wider the "Q" of the box. Since my room's peak is really severe, I guessed that I wanted a very high peak resonance and narrow Q, so I used only a little absorption. First mistake.
Once I built the cabinet and drilled the holes my second mistake was obvious. Having used low grade MDF without crossbracing, the box was clearly resonant in a bunch of midrange frequencies just exactly like you'd expect from a cheap MDF box without enough bracing. Unfortunately, being Very Smart I knew that vibration and air leaks were my enemies so when I built the box I used plenty of glue all around. Therefore I wouldn't be able to open the box to correct the bracing problem or add absorption. Third mistake. I've built subwoofers before, I know better than this. I felt like a right numpty. Oh well, it was a beta-test.
Hi again,
Just for the record, had you added any rock wool when you made the measurements shown in your posts? Or do you mean that you had planned to, but forgot to put it in before gluing everything together (meaning that the outer cloth was the only damping added)?
Your demonstration that fabric over the neck is effective is quite significant, as this seems much more practical to implement than titrating mineral wool into a sealed box.
And just to confirm (sorry if this should have been obvious), all the measurements are done with the mic at the main listening position?