I feel air from the port

[Forevrbumpn]

Arnold and Chris got the best answers in this thread

Unloading is unsafe, and usually causes a wind tunnel, not resonating air

If a port is blowing air like a compressor air nozzle, tuning is probably to high

Questions I didn't see is

"How large is your box?"

and "How is your box ported/ tuned dimensions of the box internals, and dimensions of the port?"

it could be quit possible the box was tuned wrong, maybe you expected a 30hz tuning, but got a 40 hz tuning, and the woofer will unload with a lot of chopped and screwed music or music that is being constantly played below tuning

One way to check things is get a test tone CD that steps in single digits, 30hz, 31hz, 32hz

Find the point where the woofer is barely moving at all, almost a standstill

That should be port tuning

write that number down

Now keep going low from that number ( Say you found the cone barely moves at 40hz)

Now while testing the tones, going lower, you will more than likely get the most wind- not resonating wind, but wind tunnel type wind at about 20hz

So, what I'am guessing is, your listening to music well below port tuning

Simple solution, after finding the tuning freq, use a subsonic filter to filter bass below that frequency

The harder solution, tear out, rebuild, tune lower

I highly doubt you will actually damage that SMD woofer, those things are obviously built like beasts

but again, if your running rated RMS, or higher, you may be getting in to dangerous territory with the box/filtering left alone

[Neo_frog]

like opening a hatch or rear door for ex?

Well you have to remember that majority of systems employ a box that has much lower internal space than the cab of the car. Trunk systems rely on the back side of the car (or sealed trunk) for extra loading if oriented that way. Walls are where you run into that type of problem. Each time you add more exposure to the outside air, generally the resonance spikes. Unless you know your response well, in bassboxing for example, you would have to start a bit lower and turn it up until you start to unload to get your best score. That's assuming you haven't tested and you actually care about your equipment.

But with normal trunk or hatch setups, depending on the size of the vehicle and position of the box, there's a chance that opening doors will barely affect the cone movement even though your peak frequency could change.

Here's my example from my last setup:

Enclosure: 19.7 cu; 2x DC LVL5 18s; 8kW

Sealed Cab: ~42 cu

Door: ~806 sq in.

Peak Sealed: 32hZ

Peak (one door open): 32-33hZ

Peak (both doors open): 51hZ

And doing the little test I mentioned above, I did start to hear some distortion with both doors open on normal music.

EDIT: spelling

Edited June 6, 2010 by Neo_frog

[arnold1992]

nice testing and info neo frog...that's alot of good info...