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View Full Version : for are expert enclosures plz NEED INFO ON A BOX



SQBubble
04-25-2006, 10:32 AM
I need to know what tuning and how much cu.ft is this box:
all in inches

27.5 width
18 depth
17.5 height


the port size is 4x15.5
the port length is 13.5, there is only 1wood for the port.. no labyrinth or anything like that...


thx alot

j3bus2k3
04-25-2006, 10:59 AM
IF those dimensions are your internals, your volume before DRIVER displacement is 4.55ft^3 and IF thats correct, your tuning is ~43hz. Thats using a formula off of JL's site and mind you there could be error on my part.

SQBubble
04-25-2006, 11:02 AM
IF those dimensions are your externals, your volume before DRIVER displacement is 4.55ft^3 and IF thats correct, your tuning is ~43hz. Thats using a formula off of JL's site and mind you there could be error on my part.


woow I really doudt its 4.33, it isnt really big....
but thx can u tell me were on jl's site?

j3bus2k3
04-25-2006, 11:04 AM
http://mobile.jlaudio.com/support_pages.php?page_id=165

I made a typo, I figured those numbers were internals...I edited my original post to reflect that. But also too, you dont have much of a port to displace much volume....

SQBubble
04-25-2006, 11:11 AM
But also too, you dont have much of a port to displace much volume....

wut does that mean, it could harm sub? and btw its for 1 15"

j3bus2k3
04-25-2006, 11:15 AM
Higher tuned boxes have a shorter port length and in turn just dont displace a whole lot of space in the box. Its not going to harm the sub at all. Just a geometry thing...4.5ft^3 wouldnt be that far off for a 15 especially tuned that high...

SQBubble
04-25-2006, 11:35 AM
cuz the guy that made me the box told me its a 3cu.ft tuned @32hz? but I just saw inside the box and it really dindt seem like it, (tuning)but it looks like a 3cu.ft

SQBubble
04-25-2006, 11:37 AM
and I need to know wut tuning it is... cuz I realized the sub goes low.. but it seemed weird in the low notess...

j3bus2k3
04-25-2006, 11:39 AM
Did someone on here design it? Just to clarify, are those numbers you gave in the original post external measurments? Tuned to 43hz would be the reason why it sounds "wierd" on the low notes...

j3bus2k3
04-25-2006, 11:45 AM
Just for Shits and giggles I did it figuring those were externals...I got a volume before driver displacment of ~3.5ft^3 and tuning came out to be ~49hz....

This port length measurment you listed, is this the physical port length, or the effective port length? there's a major difference....

SQBubble
04-25-2006, 11:50 AM
Did someone on here design it? Just to clarify, are those numbers you gave in the original post external measurments? Tuned to 43hz would be the reason why it sounds "wierd" on the low notes...


no its not someone over here.. and yes its the external, i just measured it...
fawkk, i told him to tune it around 30hz!! i guess hes a ******* and i learned my lesson, I aint gonna let anyone make anything for me when it comes to car audio, imma build my own box now, fawk those people, they dont care shyt ....

SQBubble
04-25-2006, 11:51 AM
Just for Shits and giggles I did it figuring those were externals...I got a volume before driver displacment of ~3.5ft^3 and tuning came out to be ~49hz....

This port length measurment you listed, is this the physical port length, or the effective port length? there's a major difference....


well I measured the piece of wood inside the box!!

SQBubble
04-25-2006, 11:52 AM
49hzzzzz :furious: , no wonderrr, it was freakin loud on the highs, like FREAKIN loud

j3bus2k3
04-25-2006, 11:55 AM
no no no...the piece inside the box is just a derivative measurment of the port lentgh. The actual and effective port length is much different. Being a 4" wide port, your effective length should be in the neighborhood of...20"s...I think?

EDIT: Redid the math with a ballpark number of 20.5" for port length and its still 42hz...

SQBubble
04-25-2006, 11:59 AM
ohh okk, so basically its around3.5 tuned @around 42hz!!

but when I play loww notes with that box, does it harm the sub? like 25-30hertzesss

j3bus2k3
04-25-2006, 12:02 PM
Harm it...I would say its possible if you dont have a sub-sonic filter set. To my knowledge, and I could very well be wrong, but the SSF prevents it from bottoming out and I'd assume that if it bottoms out frequently that it could expedite it's failure.

Chevyaudio
04-25-2006, 12:02 PM
I wouldnt play Tones that low in a box tuned that high (Im taking j3bus2k3's word on the tuning...cause im too lazy to do the math) You will run into problems with the sub bottoming out. unless of course you have your SSF set properly

bustaplz
04-25-2006, 12:03 PM
Short answer? Yes.

SQBubble
04-25-2006, 12:07 PM
shytt....

SQBubble
04-25-2006, 12:09 PM
i think I f*cked up the sub cuz of thissss





















:furious: DA*MIT:crap:

j3bus2k3
04-25-2006, 12:10 PM
sorry man... If you need a design they're are plenty of top-notch designers on here, you just need to ask who's better first. Moe Lester, Saywhat?, PV Audio, JordanTyler, just to name a few of the most respected although Moe isnt doing any ATM...

SQBubble
04-25-2006, 12:15 PM
God d*mn ****** school internet...

If a mod sees this please Delete...

lollz
well the sub makes a ****** sound when there is bass supposed to come out... and cone doesnt move..absolutely no bass, only ****** sound.... what could be this problem?

thx alot guys

j3bus2k3
04-25-2006, 12:18 PM
My first guess is that it may be bottoming out...but to be honest, I have no clue.

SQBubble
04-25-2006, 12:24 PM
nahh i dont think so, its really an anoying sound that always come out when there is any kind of bass, maybe the voice coil!!?? or somethin'...
edit*and there is no bass at all too

j3bus2k3
04-25-2006, 12:25 PM
Hmm...maybe some intereference through the RCA's? Bad ground?

UndercoverPunk
04-25-2006, 12:32 PM
You might have mushroomed the former...

SQBubble
04-25-2006, 12:34 PM
You might have mushroomed the former...

huh wut does that means?

swimfreak26
04-25-2006, 12:46 PM
j3bus, you added a bit too much when figuring effective port length, but your tuning calculations are right on.

Effective port length is ~15.5-16" and you've got a tuning right around 47-49Hz. This is assuming 3/4" MDF construction and the first 3/4" of the port being the "front" of the box (ie not causing internal displacement).

In other words, a box tuned entirely too high for daily driving. You'll reach mechanical excursion limits easily with typical bass found in rap. It sounds like you did that, and screwed up the sub :(

j3bus2k3
04-25-2006, 12:52 PM
Well, when he gave me 13.5" I added the 4" for the bend, .75" for the L2 and then end correction of 2"...I thought I was being generous...

SQBubble
04-25-2006, 12:53 PM
j3bus, you added a bit too much when figuring effective port length, but your tuning calculations are right on.

Effective port length is ~15.5-16" and you've got a tuning right around 47-49Hz. This is assuming 3/4" MDF construction and the first 3/4" of the port being the "front" of the box (ie not causing internal displacement).

In other words, a box tuned entirely too high for daily driving. You'll reach mechanical excursion limits easily with typical bass found in rap. It sounds like you did that, and screwed up the sub :(

exactly... i listen alot of rap and r&b and anything with low notes...
so there is no way to repair it? i should by a new one?

j3bus2k3
04-25-2006, 12:55 PM
Just build a new one. Not only would it be properly deisgned and built, but it would be easier than taking the top off of yours, adding a second port wall, adjusting for its displaced volume, finding a good balance...just build a new one, lol.

SQBubble
04-25-2006, 12:57 PM
Just build a new one. Not only would it be properly deisgned and built, but it would be easier than taking the top off of yours, adding a second port wall, adjusting for its displaced volume, finding a good balance...just build a new one, lol.

lolllz I was talking 'bout the sub!! haha repair a box ur crazyyy i would never do this:p:

ngsm13
04-25-2006, 12:58 PM
Wow. You got fukked.

nG

j3bus2k3
04-25-2006, 12:59 PM
IF its not totally fubar'd I'd say reuse it simply becuase I'd be too cheap to buy a new one. BUT if the thought of a new sub system tickles your groin, go for it...