Is it true that if you tune a box for 32 Hz it may drop to say 28 Hz in reality ?
I heard something like that, and I was wondering because this is what has kept me from starting on a ported box. Uncertainty regarding the port tuning.

I have the specs from Infinity, but no matter how I try, I can not come up with the same result they do. The volume/port combo they list on the specs, gives a Fb of 28.0 Hz. Port is 3 inches diameter, 9 inches long, volume is 1.75 cubic foot (includes driver/port displacements).

I've asked about this before, but not regarding tuning dropping.


What I want to try is a straight rectangular box, I'll just make the lid contoured nicely, to follow the edges of the interior panels in the back. The space I'll have empty underneath the lid, i.e. between the body panels and the box, I'd use it to mount my amp.


I'm THIS close to posting the standard

"Help !!! Need box plans !!!"

 

No box has an "on/off" type of frequency response. The type of box and the sub parameters will have an impact at how rapidly the response falls off at the low end, but it won't just immediately end at a certain frequency.

If you tune for 32hz, yes, you'll still have plenty of audible output at 28hz, not that you'd be able to hear it anyway. There's virtually NO music except for test tones that goes that deep.

Another thing to consider is that in ported enclosures, cone excursion goes WAY up at frequencies below the tuning frequency, which means that power handling below the tuning frequency is severly reduced. If you try to pump a 28hz test tone through a system that's tuned to 32 or 35hz, you'll run a high risk of blowing the speaker. Most guys that run ported systems use an amp that's got a built in subsonic filter so you can prevent overdriving your subs.

 

Ah ok, thanks for explaining it to me. Yup, that's why I haven't built the box, since why have it tuned at 28 Hz ?

Are aftermarket subsonic filters available ? My amp's a Profile California MSX600, mono sub amp, but I doubt it has a subsonic filter.

So for rock and real heavy metal, death metal, Metallica maybe some rap now and then, tune it what .. 33 Hz ... 35 ?