Why Do My Subs Play Well Below Port Tuning?

[raytard]

I know L5's kinda defy what you normally think about subwoofers, with playing well with higher tuning, wanting a vented box when t/s parameters point to wanting a sealed box.

I was told that going below a box's tuning sends the subwoofer into free-air essentially.

I was also told that going below tuning ruins the "sound" off bass, and it turns more into air whooshing around.

My last subs, totally did that, it was tuned to 32 hz, if I played 28, they bottomed out at max volume, and made no real bass, just whooshing

That being said, these L5's do the opposite, they don't really come alive until they drop below the 42 hz tuning, they overheat before they bottom out with the power i'm throwing them, and they go like a full friggin octave under the tuning, they beast 28 hz (i say that cuz that song by rich boy-she wanna has 28hz in it, after a 58hz constant beat. They barely play 58, they are noticably louder at 28)

Can anyone explain this? I'm just really curious

[BigPimpin91]

Amp settings?

Woofer Characteristics?

Vehicle resonant gains?

[Boon]

Probably coupling with the car providing additional loading on the woofer and the port.

You always have to consider the box in the car environment. Yes your box is a normal ported box tuned to 42hz in a free-space environment but as soon as you put it in a car you have created an effective bandpass enclosure that changes depending on how the woofer and port react to how much air is around them and how the air 'loads'

You can make a woofer play really low by shoving it right up against the boot/tailgate - you're effectively extending the length of the port and the woofer cannot 'unload' because it is 'loaded' by the air pressure between the cone and the car's panels.

I suppose I can go into a bit more if anyone is interested.

[Neo_frog]

Probably coupling with the car providing additional loading on the woofer and the port.

You always have to consider the box in the car environment. Yes your box is a normal ported box tuned to 42hz in a free-space environment but as soon as you put it in a car you have created an effective bandpass enclosure that changes depending on how the woofer and port react to how much air is around them and how the air 'loads'

You can make a woofer play really low by shoving it right up against the boot/tailgate - you're effectively extending the length of the port and the woofer cannot 'unload' because it is 'loaded' by the air pressure between the cone and the car's panels.

I suppose I can go into a bit more if anyone is interested.

Please.

I know where it's going, but I love dirty details.

[Boon]

I wrote a whole bunch of stuff but re-reading it I didn't like it... I'll edit and post up if I feel it's up to standard

[Sinosic]

transfer function

[raytard]

i figured it was something to do with transfer functions, but i wanted to know details=)

port is NOT LOADED, it is in an armrest, firing straight into the cabin, and at ~18sqin/cube, its friggin massive

amp gains/setting are untouched from last install, subwoofer volume on deck is low for break in (like -8 when amp does full potential at 0, subs cant really take full power, so its going to be staying lowish, till i get L7's)

and the subs, i dont know how much they can be loading off glass about a foot away, thats what was bugging me, that it seems so darn open, i knew cabin gain had something to do with it, but jeeze, playing 15-20hz below tuning is kinda strange IMHO.

Ive been told to tune to 32-33hz for daily, but come on, if i get more spl out of 42, and it can still play high 20's, what could possibly be the upside of tuning low?

edit: 2 pics so ya'll know what i mean, i know i cant explain worth a shit

port:

subs:

i know its ugly, im cleaning it up when i go home, it was a day before going back to college cuz i need bass job, in the middle of the night in snow

Edited January 27, 2009 by raytard

[07sOnAtA sp.ed]

yeah, i heard these in person, because we go to the same school, and those 8"s BEAT, especially when the low notes come on. Ray played Bubble up, by Gucci Mane, and the lows were crazy.

[Boon]

The port is coupled with the air in the car. This provides resistance and 'loads' both the port and the woofers anyway, compared to free-space.

The 'tuned frequency' of the box is only the point of resonance in a free-space environment, as soon as you put it in a car it all changes anyway because instead of 'venting' the box the port is now coupling the air inside 2 'sealed' (obviously your cabin isn't sealed but near enough) chambers.

Short answer, in any case ;/

Cool box

Edited January 27, 2009 by Boon

[kryptonitewhite]

Probably coupling with the car providing additional loading on the woofer and the port.

You always have to consider the box in the car environment. Yes your box is a normal ported box tuned to 42hz in a free-space environment but as soon as you put it in a car you have created an effective bandpass enclosure that changes depending on how the woofer and port react to how much air is around them and how the air 'loads'

You can make a woofer play really low by shoving it right up against the boot/tailgate - you're effectively extending the length of the port and the woofer cannot 'unload' because it is 'loaded' by the air pressure between the cone and the car's panels.

I suppose I can go into a bit more if anyone is interested.

excellent answer

ive always wondered where Meade's F3 is with it being a 27Hz tune iirc with the port being loaded right off the boot like that