E39 Ski pass subwoofer box - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 25 Old 01-08-2018, 03:25 PM - Thread Starter
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E39 Ski pass subwoofer box

Hello am trying to build a sub box for my BMW E39 with a ski pass but I cannot decide how should i make it. Currently am thinking if it is possible to make an angled box with flared round port? I will be using: AMP - Pioneer GM-D9601; SUB - 2 x JBL GT5-12. I want the box to be ported so all the bass gets to the cabin and also so it could fit perfectly with my rear seat. Using Sketchup I made something like this:
(I changed from centimeters to inches so you guys could understand better.) So if somebody could share their ideas it would be great
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post #2 of 25 Old 01-08-2018, 03:26 PM - Thread Starter
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post #3 of 25 Old 01-08-2018, 05:21 PM
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Keep in mind that a ported sub will be producing almost all of its output from the vents only at its tuning frequency, further up in frequency you will have output from the drivers. Stil the bassl should pass through the rear seats pretty easily.
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post #4 of 25 Old 01-08-2018, 07:09 PM
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Checkout the install subforum at the diymobileaudio.com forums. There you'll find what you seek.
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post #5 of 25 Old 01-09-2018, 06:59 AM - Thread Starter
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Ye I know, I calculated everything with sub calculator I know what size port and everything else I need to tune it to 32 Hz but what I wanted to ask is angled vented box okay or should it stay not angled if I want ports because I could not find any examples on web with something like I made. Also I wanted to ask if it is okay how I made it how am supposed to measure the 2 port lengths because one is lower than another?
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post #6 of 25 Old 01-09-2018, 10:52 AM
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Quote:
Originally Posted by AndriusLT View Post
Ye I know, I calculated everything with sub calculator I know what size port and everything else I need to tune it to 32 Hz but what I wanted to ask is angled vented box okay or should it stay not angled if I want ports because I could not find any examples on web with something like I made. Also I wanted to ask if it is okay how I made it how am supposed to measure the 2 port lengths because one is lower than another?

You can install the ports to they are perpendicular to the cabinet face, there’s no rule that they have to be pointed straight.



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post #7 of 25 Old 01-09-2018, 02:23 PM - Thread Starter
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Okay but how should I measure the ports on this angled box?
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post #8 of 25 Old 01-13-2018, 08:57 AM - Thread Starter
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So how should I measure them?
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post #9 of 25 Old 01-13-2018, 02:19 PM
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E39 Ski pass subwoofer box

Quote:
Originally Posted by AndriusLT View Post
So how should I measure them?


It’s not super critical, you could use the middle range of the length if that makes sense.

Edit, are you leaving them sticking out or cutting flush? If sticking out, just the length. If cut at an angle, the midpoint between top and bottom.

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post #10 of 25 Old 01-13-2018, 02:38 PM - Thread Starter
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I think am gonna leave them like that not cut. I calculated everything and exported to SketchUp, correct me if am wrong somewhere
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post #11 of 25 Old 01-13-2018, 03:31 PM
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You might have less turbulence at the outlets if you cut them flush


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post #12 of 25 Old 01-13-2018, 03:34 PM - Thread Starter
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Okay so if cut them flush I don't need make the port longer or something?
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post #13 of 25 Old 01-14-2018, 11:02 AM
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Quote:
Originally Posted by AndriusLT View Post
Okay so if cut them flush I don't need make the port longer or something?


You could add half the length of the angled part that’s cut off.


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post #14 of 25 Old 01-18-2018, 02:01 PM - Thread Starter
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Guys am I measuring the port the right way? (Picture) 54.10 cm + 15.90 cm x 2 = 85.90 cm
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post #15 of 25 Old 01-19-2018, 12:48 AM
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Quote:
Originally Posted by Pradeep2 View Post
...Stil the bassl should pass through the rear seats pretty easily.
Having owned a lovely 540, I would disagree strongly. The seats are really thick and had a hard backing, metal IIRC. Mine were fold-down plus the ski-pass. Fixed seats also not so transmissive. Way back when, yeah, the bass would go through back seats more easily but now less so.
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post #16 of 25 Old 01-19-2018, 01:02 AM
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Quote:
Originally Posted by AndriusLT View Post
Hello am trying to build a sub box for my BMW E39
For my 540, I had a shop fiberglass an enclosure into the side "scoop" at the very back of the trunk. They integrated the original release latch, so I could still access behind to get at the battery or fuses or whatever it was. That was pretty good, though not going to crack the windows due to small enclosure size. As I noted in the other post, I would NOT put woofers right up against the seat back.

With the sub box somewhere else, the ski pass through makes a kind of port compared to the trunk "enclosure" so in theory there could be a bandpass effect, but it didn't seem to be an issue at least with my layout.

One alternative could be to make a slot that would fit up to the ski-pass, with woofers mounted inside the slot
http://www.hifizine.com/files/2012/0...pen-baffle.png
http://www.hifisentralen.no/forumet/...jesus-slot.jpg
or like half of this thing if you have space; the push-pull reduces distortion
http://techtalk.parts-express.com/fi...tch?id=1181646
http://www.hifizine.com/files/2012/0...tz-W-frame.png
If you wanted to be really tricky, taper/angle slot so the woofers almost touch at the back side. That could reduce some slot resonances, and *theoretically* have better airflow. Then again, woofers directly facing each other cancel out some vibration.
I don't recall the ski-hole as being large enough to fit a slot for 12s AND fire ports through. And NO, don't fire them through the slot, the airflow won't work. Actually 2 12s sealed with good amplification will get a lot of SPL in the car-if it is not enough, build something huge and just drive around with the back seat folded down!
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post #17 of 25 Old 01-19-2018, 06:18 AM - Thread Starter
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Okay I wanted to ask about port length. In the picture all port length would be 54.10 cm + 15.90 cm = 70 cm ? (Correct me if I am wrong)

And also from where should I start measuring the port if it is angled?
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post #18 of 25 Old 01-19-2018, 10:10 AM - Thread Starter
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Quote:
Originally Posted by head_unit View Post
For my 540, I had a shop fiberglass an enclosure into the side "scoop" at the very back of the trunk. They integrated the original release latch, so I could still access behind to get at the battery or fuses or whatever it was. That was pretty good, though not going to crack the windows due to small enclosure size. As I noted in the other post, I would NOT put woofers right up against the seat back.

With the sub box somewhere else, the ski pass through makes a kind of port compared to the trunk "enclosure" so in theory there could be a bandpass effect, but it didn't seem to be an issue at least with my layout.

One alternative could be to make a slot that would fit up to the ski-pass, with woofers mounted inside the slot
http://www.hifizine.com/files/2012/0...pen-baffle.png
http://www.hifisentralen.no/forumet/...jesus-slot.jpg
or like half of this thing if you have space; the push-pull reduces distortion
http://techtalk.parts-express.com/fi...tch?id=1181646
http://www.hifizine.com/files/2012/0...tz-W-frame.png
If you wanted to be really tricky, taper/angle slot so the woofers almost touch at the back side. That could reduce some slot resonances, and *theoretically* have better airflow. Then again, woofers directly facing each other cancel out some vibration.
I don't recall the ski-hole as being large enough to fit a slot for 12s AND fire ports through. And NO, don't fire them through the slot, the airflow won't work. Actually 2 12s sealed with good amplification will get a lot of SPL in the car-if it is not enough, build something huge and just drive around with the back seat folded down!
So if I wanted to build a box like that (Picture) even if everything is calculated to be tuned to 32 hz (port and etc.) and fit the box close to the back seats (the front is angled about 65 degrees like the back seats) and port facing ski pass (the ski pass would be open all the time) it would not be a good idea?
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post #19 of 25 Old 01-20-2018, 06:01 PM
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E39 Ski pass subwoofer box

Why not wrap the port up the back and do a top exit?

Edit, I bet yours is a sedan, I had a wagon so I’m thinking of that.

Maybe consider a partition dividing the port into top and bottom so you can equalize the length better? Not sure how that would work inside but maybe?

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post #20 of 25 Old 01-20-2018, 06:06 PM - Thread Starter
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Did something like this (Pictures) am also gonna cut the rear deck speaker holes so the output from subs would get into cabin as well as the air from the port to the cabin. What do you think? p.s Ye its a sedan
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post #21 of 25 Old 01-20-2018, 06:11 PM
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Quote:
Originally Posted by AndriusLT View Post
Did something like this (Pictures) am also gonna cut the rear deck speaker holes so the output from subs would get into cabin as well as the air from the port to the cabin. What do you think? p.s Ye its a sedan

I’d go ahead and port up then and not have the angled exit. The holes in the deck should be plenty



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post #22 of 25 Old 01-20-2018, 06:16 PM - Thread Starter
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The holes will be only this size for the subs and having the ski pass I thought about doing the port like that that would fit nicely (angled) to the backseats (the ski pass would be open all the time).
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post #23 of 25 Old 01-22-2018, 11:34 AM - Thread Starter
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Finally made something am happy with. What do you guys think? Also I want to ask is it okay if put subs in the back and port to front, the distance from port to drivers will not be enough so to correct that i put the subs a little bit to the sides so they could sit nicely beside the port is that okay?
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post #24 of 25 Old 01-22-2018, 12:25 PM
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Have you cut the skipass "bag" out? On my 325 you drop the armrest, and the bag/cloth can expand into the cabin, but there didnt seem to be a readily available way to actually pass things back and forth with the bag in place.
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post #25 of 25 Old 01-22-2018, 01:09 PM - Thread Starter
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I have fold down rear seats and a ski pass. Yes I unscrewed the bag out with the plastic opener so when I drop the armrest I can reach into trunk easily thats why am making ported box through a ski pass Anybody can confirm that the design is correct?
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