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Discussion Starter · #1 ·
What's the most anyone has done/seen/heard without issue???


Goin' IB for the month of June. I'd like to put a pair of 15"s back there, but I've gotta fire them through a 10x11" ski pass. I'm wondering if there'll be any adverse effects, or will I be forced to go with 12"s?

One other question, if I'm to aim these forward with the motor toward the trunk, how much space should there be from the cone to the seatback.



Thanks!!!
 

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Why do you need to fire them through the skipass? Is there metal directly behind the seats? You won't have any problems (especially with 2 15's) firing through the seat foam. I have 2 10's IB firing through the seats and they sound great.
 

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If it was a green IS300 that Jeff Smith did, then those were 15s.
 

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Those are 15s. I don't think there was any metal cut behind the seats.
 

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You can make a manifold, with the woofers firing towards each other, perpendicular to the opening. Basically a box with one side open venting through the ski pass. This coupling will actually lower the FS slightly and increase the power handling of the woofers.

You can either wire the sub-woofers in phase, firing towards each other. Or you can wire them out of phase and flip one of the woofers so they are both facing one direction, like so:

|> |>

This will effectively decrease some of the motor distortion, at least in theory.
 

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What's the most anyone has done/seen/heard without issue???


Goin' IB for the month of June. I'd like to put a pair of 15"s back there, but I've gotta fire them through a 10x11" ski pass. I'm wondering if there'll be any adverse effects, or will I be forced to go with 12"s?

One other question, if I'm to aim these forward with the motor toward the trunk, how much space should there be from the cone to the seatback.



Thanks!!!
Optimally the ski pass opening should be equal or greater than the combined SD of the woofers....

so your Ski pass is 110 inches squared, then optimally the subs SD should be around that number......Now to be honest, I really dont think it will matter too much if you are within about 25 percent of the combined SD figures.

Anything less than 75 percent and you could start losing output, but the power handling will go up due to more pressure on the front of the cones...

The box can start to act as a a bandpass enclosure....kindof....

But just remember, the sub will move different amounts of air depending on the music. So that is where the 25% comes from.

Dont really know how else to explain it.....
 

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I have 2 12's firing thru the ski pass in a bmw 745. i built a rectangular box and placed the woofer on the outside facing one another from the opposite side of the box. they are in phase and they sound great.
 

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Discussion Starter · #13 ·
I have 2 12's firing thru the ski pass in a bmw 745. i built a rectangular box and placed the woofer on the outside facing one another from the opposite side of the box. they are in phase and they sound great.
Do you have any pics of this setup?

That's a coupe with no ski pass and with leather.
I've seen that thread. Full of EXCELLENT info. But the ski-pass is exactly what concerns me.



Thanks for all the help, everyone!!!!!
 

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I can fire huge subs through a ski pass with a big enough gun....
 

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I've seen this guy:





Dunno if he cut out the seatback, though. Usually you'd see a bit of metal just beyond the seat.
i had a 15 minute demo in the driver's seat of this car.....and :eek::eek::eek::eek::eek:
if you are worried about the size of your ski pass,just hole saw some 2'' holes in your seat back's metal plate.
 

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What's the most anyone has done/seen/heard without issue???


Goin' IB for the month of June. I'd like to put a pair of 15"s back there, but I've gotta fire them through a 10x11" ski pass. I'm wondering if there'll be any adverse effects, or will I be forced to go with 12"s?

One other question, if I'm to aim these forward with the motor toward the trunk, how much space should there be from the cone to the seatback.



Thanks!!!
I don't think it will be a problem.

Think about it this way. Some people build bandpass subwoofers where the output of a fifteen inch woofer is being redirected through a four inch port. Is there any ill effect?

Admittedly, if you were feeding your fifteens ten thousand watts each you'd start to run into resistance. (There's only so much air that you can cram through a vent.)

But you're not using a 20,000 watt amplifier -

So don't worry about it :)

As a rule of thumb, I wouldn't use an opening that's any smaller than 10-20% of the cone area. So if each fifteen has a cone area (SD) of 150ci, you'd be alright as long as the opening is between 30-60ci. So an 8" x 8" opening would give you plenty of output.
 

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Discussion Starter · #19 ·
I kinda pussed out and got the 12"s for the sake of easy install, also. There's actually only ~31.5" between the wheel wells of this car.


Think about it this way. Some people build bandpass subwoofers where the output of a fifteen inch woofer is being redirected through a four inch port. Is there any ill effect?
Here's a neat IS300 install with 2 10"s BP:



 

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sorry to butt in...but im assuming the "ski pass" is between the seats?? or no? fill me in please haha
 
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