View Full Version : how much louder is ported

11-20-2002, 12:04 AM
I bought a set of 12 inch l7s and a bd 1000.1 amp in a 1cubic foot per chamber sealed enclosure it hits hard but sometimes there is a wier noise coming from one of the woofers is it blownand its not as loud as i expected that is begining to **** me off. if i got a ported box how much louder would it be:mad:

11-20-2002, 02:06 AM
maybe the box has a leak somewhere...strip the carpet and use either silicone or an undercoat spray...

Ported...hmm, I've just finished off carpeting my sealed box, and maybe in about 6 months later, I'll try a ported... but yeah, does it make a whole shitload of difference? Or is it more for bringing out the frequency?

11-20-2002, 02:27 AM
hmmm, then it's a darn pity my subs were designed for sealed enclosures...

waht do you figure though, Jmac? Think I could pop 'em into some ported ones?

the subs are used a old Rockfords... RFP-1810 (8ohm)

11-20-2002, 03:04 AM
Well, I don't know about all that EBP figures...

but I do have the technical sheet for my subs:


fs : 26Hz
Qms: 4.7
Qes: 0.29
Qts: 0.27
Vas: 77L (2.72Ft^3)
Bi: 18.2Tm
Xmax: 8mm
Spl: 88Db
Sd: 54.26in^2
200W RMS

would these figures help out?:)

11-20-2002, 08:29 PM
1.5 per speaker? Cause I've just built a box that' 1.509 Cu.Ft for both speakers with a common chamber... the diameter of the port, I udnerstand...but you mean I need to shove that pipe in to all that length into the box? If it's 3in in diameter, would it be alright if I split that into two ports? i.e., 1.5" X 2? Or would that make my box just a plain pile of glued-on heap of rubbish?

11-20-2002, 08:40 PM
Originally posted by Jmac
1.5 ft^3 per sub is pretty much the same as 1.5 ft^3 shared (A little different because of the air pressure).

Actually, 2 separate ports would mean that each port would have to be LONGER than a single port, so that's not really an option. Also, 1.5" ports would create HORRIBLE port noise. If the box is 1.5 ft^3, I don't see how fitting a 12" long tube in there would be a problem, though ...

Ah, I didn't know that it was the same...:confused:

Well, the manufacturer's recommended size was a sealed .075, and since I had two, I multiplied it by 2 and after designing, the size came up to 1.509... if you care to see the picture gallery, I've uploaded my boombox. The only way it's sharing the chamber is by this tunnel I had to make along the way...:p

I COULD fit the port SOMEWHERE, and does the placement of the port matter much or would an untrained ear like mine not be able to tell a difference? the only place where 12" is gonna fit is from the right side of the wall running a bit into the tunnel, as the banana cups have been installed slightly to the left and so the wires won't really get in the way... but the exit of this port would be the inner fender bulge and would have VERY little clearance for air to push and pull:banghead:

What do you think? After your advice, I wanna go out and buy a port... it's my first and I wanna make it the best I can...:D

11-20-2002, 08:56 PM
If from the side, then about 10" without a problem, but with port exit clearance problems...

If from the top, then perhaps a 8~10"....wait a minute...
does it matter a great deal if the port end in the chamber has enough clearance? the height of the box is 12" with wood...

If from the rear, about 6~8 to clear the sub basket...

11-20-2002, 08:58 PM
yeah, 40hz sound slightly high...:(

I was thinking in the region of low to mid 30's...

Hell, if my side had enough clearance on the exit, I could put in a 24" without a problem too...:banghead:

I'm not a basshead, but as an untrained ear, I am led to thinking a low note is impressive... naive, I know, but what can I do? ;)

I just don't want the rear soundwaves to get wasted..I wanna hear it all..:D

Don't really listen to rock, more to R&B...

SInce I've got a coughing and wheezing amp to push my subs, I'd need the most out of this install before (hopefully) getting prize money from sniping and get myself a mono amp..;)

11-20-2002, 10:51 PM
Originally posted by Jmac
You generally want to leave at least 3" of clearance between the bottom of the box (assuming the port is coming from the top). I don't know the exact reason because I've never really asked, but I think it's because it would cause odd noises from turbulence.

3"x10" long would be about 32 Hz, so that would look promising ... 3"x9" would be about 33 Hz ... 3"x8" would be about 35 Hz ...

If it's 12" high, then a 9" or 8" long port would be great ...

Ok, so now I'm thinking of a 8" for enough clearance to minimise turbulence....

Just curious though...what do you think about bent ports? Like an L shape or something? Would that bend screw up compression, just like exhaust pipe bends?

If it's possible to bend, then I could have it 20 inches long..;)

11-21-2002, 03:17 AM

Ok, THIS I didn't expect.........:banghead:

ok, my sub's rec. size is 0.75Cu.Ft as I told you before... and I thought "hey, since I've got two, I'll multiply that number" hence, the 1.5Cu.Ft of space....:banghead:

now I've got an enclosure double of what I need... if this 1.5 can be put to good use for ported enclosure, I'd be a very, very, very happy man... so, judging from the nubmers that you gave me, do you think that my subs will sound good or at least tolerable in a 1.5 Cu.Ft. ported box?:(

If that is so, then I'd need to order a rockford vent soon... if not, well, scrap it all and start building one from scratch... if I make one from scratch, what size do you think would sound good on my subs for a ported enclosure?

SOmeone in another forum said that the double-sized box would have a good low-end response but a horrible peak... i don't exactly know what that means, but I don't like the sound of it... I want to be able to feel my bass notes as well as hear them clean without unwanted noise. ****, dman, ****...:banghead: :banghead: :banghead:

11-21-2002, 05:02 PM
I have seen approx and 8-9 dB gain at most

11-25-2002, 09:43 PM
Any of u smart people out there wanna help me out on what type of enclosure would be best for my 2JL12W7's? Any help counts thanks.

11-25-2002, 09:58 PM
Originally posted by ///M3bumping
Any of u smart people out there wanna help me out on what type of enclosure would be best for my 2JL12W7's? Any help counts thanks.

Why not check JL audio's web site? They know best when it comes to what their subs can do and cannot do... if in doubt, use recommended size~

11-27-2002, 01:08 AM
being the owner of an L7 12" myself, i thought i would give my opinion...
before all of the porting talk between you and Jmac, your question "Does a ported sound much different?", I would have to say it makes all of the difference. I have a solo solo-baric and after having it in a sealed box for a couple of months, I wanted to find out for myself what more I could get out of it, so i built the ported box with the specs kicker included, or you can find here http://www.kicker.com/images/manuals/02SL7TechManualV2_0.pdf
( i don't know if you got these or not, i don't think you've said anything)
I couldn't believe the difference, although as everyone says, the SQ is not-so-great and the bass is not as punchy, but **** does it throw out some low bass.

11-29-2002, 12:33 PM
i dont know what yall are talking about, but an 8 MM X-max ***** hard. and... im done.

11-29-2002, 09:46 PM
Originally posted by snitchelgroovin
i dont know what yall are talking about, but an 8 MM X-max ***** hard. and... im done.

What exactly do you mean by ***** hard?

11-30-2002, 11:20 PM
well, i guess its not SO bad, but it wouldnt seem like an 8mm xmax would hit very hard. maby they are just small subs though...

12-01-2002, 12:17 AM
how would a 2.5 in diameter and 4 inches long work with a single 12w3 in a 1.5 cubic feet box???