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Slot ported enclosure - wedge type possible?


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#1 joms

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Posted 05 Feb 2010 - 22:22

Given:

Subs = JL 12W7
Amp = JL HD750/1
Box = Slot ported Enclosure (with very steep wedge on rear)
Internal Volume = 1.75cu ft NET as per JL's recommendation
Length = 22 inches (max)
Height = ??
Depth(top) = ??
Depth(bottom) = ??

Can i make a slot ported wedge box that is very slanted in the rear? If so, would the port inside the sub be slanted as well or should it be straight? Tnx

As per pics shown below, do you think this will work on my JL12W7? This is not the exact dimension ( I didn't take into account of the dimension). I just did this to try ang show you guys what I have in mind. I intend to make the distance of the driver's magnet to the rear board that makes up the port only 1" on the top part. The bottom part will have a larger clearance as the board is slanting. See pics below

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JL Audio's Recommended Slot Port Box (as per their website):
*note, it doesn't have a wedge back though which is what I want/need.

Posted Image

External Dimensions - 22.75 in. x 15.5 in. x 15.5 in. (Width x Height x Depth)
Slot Port Internal Dimensions - 1.75 in x 14 in x 24.0 in. (Slot Width x Slot Height x Slot Length)
Volume - 1.75 cu. ft (net int.)

#2 WonkyJon

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Posted 05 Feb 2010 - 22:26

it's not ideal, but will work. the problem is that the top of the port is shorter than the bottom of the port. account for this and it'll work better but look very odd!

in your drawings you have a smaller port opening than the actual port dimensions. you arent planning on building it like that are you?

#3 joms

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Posted 05 Feb 2010 - 23:32

nope, the port opening will be open like the one on JL's pic. So this is doable? what will be the disadvantage?

#4 WonkyJon

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Posted 05 Feb 2010 - 23:57

As I said, the port is shorter at the top than at the bottom. the ideal way to deal with this is angle the inner port piece so you negate this issue. a bit of maths, cut the MDF, job done.

the easier and often used option is to just take the port length as the central length, it's not ideal, but will work.

personally, I'd figure out a way to use round ports or make the port straight, not slanted.

#5 eddhick

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Posted 06 Feb 2010 - 00:13

How about slot porting across the bottom of the box instead? Making a wider thinner port of some sort? That way the port will be the same size everywhere. Only thing is if the slot has to fold upward the back corner thats a tight turn!

#6 WonkyJon

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Posted 06 Feb 2010 - 00:40

Or across the top, then it's not a tight turn at all :)

#7 eddhick

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Posted 06 Feb 2010 - 09:51

Ahh yes of course! Good call!

#8 Medzy1506

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Posted 28 Feb 2012 - 20:51

As I said, the port is shorter at the top than at the bottom. the ideal way to deal with this is angle the inner port piece so you negate this issue. a bit of maths, cut the MDF, job done.

the easier and often used option is to just take the port length as the central length, it's not ideal, but will work.

personally, I'd figure out a way to use round ports or make the port straight, not slanted.


Sorry to bump this but what do you mean by taking the port length as the central length ? could you explain that a bit more ?

#9 boozydave

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Posted 28 Feb 2012 - 21:09

measure the length at the centre of the slope, for a rough guide


port length needed = 24
so, total length at the top of the port could be 19, and at the bottom 29, tuning will differ top to bottom, say 40hz to 35hz,
if you slant the internal end of the port by the same measurement as the slope, it will be the same length at top and bottom and will tune to a certain hz

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#10 Medzy1506

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Posted 29 Feb 2012 - 10:33

measure the length at the centre of the slope, for a rough guide


port length needed = 24
so, total length at the top of the port could be 19, and at the bottom 29, tuning will differ top to bottom, say 40hz to 35hz,
if you slant the internal end of the port by the same measurement as the slope, it will be the same length at top and bottom and will tune to a certain hz


I'm still really confused :blush: :confused: thanks for hte reply either way, i did find it somewhat helpful but im still confused lol!

could you dumb it down a bit more please ? sorry for sound like a noob

#11 Jason_D

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Posted 29 Feb 2012 - 12:04

If it was me I would put the subs and port both facing upwards. Port along the back if the box. No complicated angles, simple to build and IMO would be better than the subs facing the tailgate.

Obviously this isn't possible in a saloon! What car is it going in?
2 x DC Audio Level 5 18"
2 x Sundown SAZ 2500's
40Hz= 155.3dB
33Hz= 157.6dB
25Hz= 156.3dB
20Hz= 153.4dB
Peak= 157.6dB @ 33Hz
Total Average= 156.0dB

#12 Medzy1506

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Posted 29 Feb 2012 - 12:19

<p><p>

If it was me I would put the subs and port both facing upwards. Port along the back if the box. No complicated angles, simple to build and IMO would be better than the subs facing the tailgate.

Obviously this isn't possible in a saloon! What car is it going in?


Thats similar to how i want to do it, I want to basically make a box similar to the OP's one thats been posted above (same slanted back) however i want to put the port and the subs facing upwards instead of where he's put it.

My two 12W7's will be going into a hatchback (2007 Seat Ibiza) in a ported enclosure. So there'll be one sub on the left, port in the middle and one on the right. Ideally thats how i'd want to do it. Is that possible ? Or would i need to put the two subs next to each other and then have a port on the left or right of the top of the box.

http://www.talkaudio...rted-enclosure/ <-- theres a link to my thread asking the questions

Edited by Medzy1506, 29 Feb 2012 - 12:22.


#13 Jason_D

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Posted 29 Feb 2012 - 13:17

You could do it with the subs either side and port in the muddle, but from what I have learnt and been told it would sound better and possibly be louder with the port across the back. I'll find a pic for you of my old boot install, it might give you some ideas.

Pic:

Posted Image

That had a slanted back behind the seats, and the seats needed a good ol slam to shut.

Edited by Jason_D, 29 Feb 2012 - 13:21.

2 x DC Audio Level 5 18"
2 x Sundown SAZ 2500's
40Hz= 155.3dB
33Hz= 157.6dB
25Hz= 156.3dB
20Hz= 153.4dB
Peak= 157.6dB @ 33Hz
Total Average= 156.0dB

#14 Medzy1506

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Posted 29 Feb 2012 - 13:39

You could do it with the subs either side and port in the muddle, but from what I have learnt and been told it would sound better and possibly be louder with the port across the back. I'll find a pic for you of my old boot install, it might give you some ideas.

Pic:

[IMG]http://i634.photobuc...09/P3130063.jpg[/IMG]

That had a slanted back behind the seats, and the seats needed a good ol slam to shut.


Jason_D thats basically how i want mine to look however im going to have the amps mounted differently and have a cover panel for the subs. Are those 18s ?

#15 Jason_D

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Posted 29 Feb 2012 - 15:02

Yeah, they r 18's. If you look through the start of my build log you will see how I mounted my amps after that. I moved them to make my port larger, and they looked much better after that.
2 x DC Audio Level 5 18"
2 x Sundown SAZ 2500's
40Hz= 155.3dB
33Hz= 157.6dB
25Hz= 156.3dB
20Hz= 153.4dB
Peak= 157.6dB @ 33Hz
Total Average= 156.0dB

#16 Medzy1506

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Posted 29 Feb 2012 - 15:45

Thanks Jason_D! I'll probably PM you if I have further questions if thats okay. you've been a great help so far. If i wanted to put the port in the middle how would i go around that ?