Volume Displaced by Driver in DIY Cab?

[bgavin]

I got it. Bill uses mattress toppers to line his boxes. He says no change in effective volume, so I say "go with Bill" cuz I haven't tested it.

There comes a point when sufficient volume is filled with "material" that it changes the internal operating mode. How much volume that is, is unknown to me.

 

[billfitzmaurice]

There comes a point when sufficient volume is filled with "material" that it changes the internal operating mode. How much volume that is, is unknown to me.

With sufficient damping material the Q of a sealed box can be lowered, taming the resonant peak in the midbass that accompanies a Q higher than .8 or so. When people refer to stuffing a box to 'fool' the driver into thinking it's in a larger box this is what they're referring to, though it doesn't actually work that way, as the fb remains unchanged. In a vented cab excess damping is of no benefit, it just makes the cab sound dead.

 

[Petebass]

.... In a vented cab excess damping is of no benefit, it just makes the cab sound dead.

That agrees with what I've read and with my DIY experiences. The benefit in lining the internal walls lies mainly in the mids and highs, preventing them from bouncing around the cab. The low frequencies go straight through the lining. In fact there's no need to line a dedicated sub.

Given that box volume affects low frequencies, and low frequencies are unaffected by the lining, there's no need to adjust cabinet volume for the internal lining.

 

[qts]

Thanks guys, i'm verry pleased and learned a lot.

 

[qts]

Here's an interesting thread

http://www.talkbass.com/forum/archive/index.php/t-213350.html