sub and port firing position in sedan - Audio & Electronics Forum

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sub and port firing position in sedan
Friday, July 22, 2011 12:18 PM
i have a 4 door sedan with rear fold down seats that i keep down 95% of the time
and i have 2 12' ported
would it sound best if i face them forward toward the cabin or rear towards the trunk??
what about port placement? front, rear or side?

Re: sub and port firing position in sedan
Friday, July 22, 2011 1:16 PM
I was wondering this as well, I plan to put subs in sometime (2 12 incher's ported) I hardly ever have passengers in my back seat, and when I do the music is down anyway. Would it be better to have a forward facing box or keep it rear facing?
Re: sub and port firing position in sedan
Friday, July 22, 2011 1:33 PM
theoretically having them face the trunk should boots transfer function @ lower frequencies however the downside is extended group delay and more vibrations caused by trunk flex. having them face the front should provide better transience response and overall SQ if i could somehow seal the trunk opening from the subs/port
some1 correct me if i am wrong
Re: sub and port firing position in sedan
Friday, July 22, 2011 1:35 PM
*boost
Re: sub and port firing position in sedan
Friday, July 22, 2011 3:12 PM
You should be able to easily make a beauty board to go across the opening lined up with the angle of the back seat.. I have thought of how I would do this before.. I just don't know what there is to lose or gain by having forward facing. My biggest issue is space. I usually have my trunk completely empty but my strut tower brace limits me to a box 14 inches tall, which doesn't leave much room for 12 inchers, or anything bigger than that. So I wanted forward facing with angles on both the seat and trunk side to match the back seat and then to clear the strut tower brace. this would also leave me ample space on the back side of the box to mount amps/capacitors and make it look nice.. not just having an amp screwed to a random board in the trunk like some people that I have seen.
Re: sub and port firing position in sedan
Friday, July 22, 2011 3:25 PM
to save some space you might consider using tire well to extend enclosure build..
there should be a good cu ft of space there
i think that you got nothing to lose by facing them forward, if what you should gain SQ
Re: sub and port firing position in sedan
Friday, July 22, 2011 3:54 PM
LMFAO... why do you use such big words? to make urself feel smart? port to the side, and subwoofer forward... try it out. i bet it sounds great. i messaged you




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Re: sub and port firing position in sedan
Friday, July 22, 2011 4:03 PM
what's the advantage of porting to the side as opposed to front or rear??
Re: sub and port firing position in sedan
Friday, July 22, 2011 6:16 PM
i had a single 12, sub back port to the driver side, box was on passenger side, loved it. also took up like no space.



car audio noob since 1984.
Re: sub and port firing position in sedan
Friday, July 22, 2011 9:22 PM
Andrey B wrote:what's the advantage of porting to the side as opposed to front or rear??


Wall is more solid. Less huffing from the trunk lid.



Re: sub and port firing position in sedan
Sunday, July 24, 2011 7:47 PM
bradsk88 wrote:
Andrey B wrote:what's the advantage of porting to the side as opposed to front or rear??


Wall is more solid. Less huffing from the trunk lid.


X2




click sig for my car audio videos

Re: sub and port firing position in sedan
Sunday, July 24, 2011 8:10 PM
yeah but wouldn't you get a lot of cancellations from the waves bouncing off every which way if ported to the side??
Re: sub and port firing position in sedan
Sunday, July 24, 2011 8:37 PM
Andrey B wrote:yeah but wouldn't you get a lot of cancellations from the waves bouncing off every which way if ported to the side??


That's why you test different spots and see what works best.

The trunk isn't a predictable "oh this will cause cancellation" scenario. It's got all kinds of whacked up curves that would be incredibly difficult to model and empirically predict.

But enough people have tried this configuration that I can say pretty confidently that it will probably work well.



Re: sub and port firing position in sedan
Sunday, July 24, 2011 9:28 PM
well, i won't get a chance to 'experiment' with it since my box will take up the whole trunk.
i want to design and calculate everything prior to building it.
now, with regards to tuning
i have a cobalt sedan so based on interior measurements i did some rough estimates and this is what i got
i calculated my first resonant frequency to be about 75 hz at say 10db octave
now i want a more or less smooth frequency response from 30 to about 60 so i would have to tune to about 30-32 hz to achieve what i want
but i am afraid i'd get cancellations in around 30 hz since it'd be exactly 1/4 of the length of my car..
it's too difficult to predict the end result but i want to at least try my best ..
Re: sub and port firing position in sedan
Monday, July 25, 2011 6:18 AM
your over thinking this...

a typical trunk will like 1 of 2 things (in a cavlier it loves EVERYTHING) either port back/Forward or port to the side. seeing as you are not happy with port back (given your specs arent up to snuff) so there for porting to the side is your next move. given you can and will spend money alot of money gettgin the exact everything you want. build a box thats 4 cubes, and has about 50 sq of port for a slot or 3 - 4" aeros/1 - 6" aero port to side tune to 33-34 hz. youll love it!




click sig for my car audio videos
Re: sub and port firing position in sedan
Monday, July 25, 2011 8:14 PM
alright brotha
i am already on it..
i am gonna need a 200 amp alternator and at least a couple of kinetic batteries
any recommendations on where to get one that's not overrated?
Re: sub and port firing position in sedan
Tuesday, July 26, 2011 5:19 AM
if u want to test, just start with a smaller test box. id be curious to see where you were at if you sealed off the trunk from the interior (reducing the space u need to pressurise by a good 25% and then facing the sub forward and the port up thru the rear deck to use the glass to your advantage. pointing the box towards the rear really isng boosting the transfer function. its more or less a good way of minimising cancellation. you get allot of canellation by just facing the sub forwards but not sealing the trunk from the interior. turning the box around minimised that because 90% of the people don't want to take the effort of sealing the area between the two.

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Re: sub and port firing position in sedan
Tuesday, July 26, 2011 7:06 AM
that's a good idea actually.. definitely less cancellation that way as opposed to porting to the side
Re: sub and port firing position in sedan
Tuesday, July 26, 2011 8:06 AM
... sealing isnt wortht he effort, no matter what you will get cancelation from the rear wave. fire forward everything and your car will want the trunk open to stop concelation.... it will not sound good...




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Re: sub and port firing position in sedan
Wednesday, July 27, 2011 4:48 AM
how do you figure, sealing off the trunk. you have now cut off 25% of the area you were trying to pressurise. do you not agree that say having a 10" sub in a 5' room would be pressurise more air then a 10" sub in a 20' room? there is a reason why it takes more bass in a suburban then a s10. as for not sounding good. its what allot of sound quality competitors do. your basically creating a new back end with the sub mounted on it. so there is no rear wave for the most part because there is no way for the wave to get behind the sub, from a sound quality standpoint i feel its the best layout. i'll put my 2 10's up against whatever setup your running anton from a sound quality aspect.

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Re: sub and port firing position in sedan
Wednesday, July 27, 2011 6:09 AM
im in agreeance for the most part. when it comes to the room to pressurize then yes, sealing would make it smaller, but it also changes the acoustics of the vehical. really comes down to listening position, not how much air to pressurize. im going off experience when i say you will get cancelation by sealing the trunk off or firing completely forward. every single sealed trunk build ive seen is about 1 db louder with the trunk open due to cancelation. it always plays the high notes WAY more promently and the flatness just isnt there. now this is what ive seen. ive seen them tuned low, ive seen them tuned high. they both sound the same, very peaky...

now to the OP, i would probly scale down to either 1 12 or 2 10s (with your given space) because really to get the best most flat response firing to the rear is usually the best. however in this case with 2 12s, IF you can get the 4 cubes you need after disp subwoofer forward and port to the side would be the next best thing. you wil NOT be happy with the turn out of the forward fire port and sub, with how much actual work is involved to get it just right and then if it doesnt work all the work to just go back to what you have now...

Another thing i would like to suggest is to hit up Pete at PWK and pay him 50$ for a design, he will really get you the best enclosure for what your wanting to do...




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Re: sub and port firing position in sedan
Wednesday, July 27, 2011 7:22 AM
looks like ported enclosure just won't work for me
i am thinking about either building rear loaded horn or t line or maybe 6th order bandpass
these enclosures i can tuned exactly to where i want them and tune them really low and even calculate standing wave so i won't get any cancellations
what do you guys think?
Re: sub and port firing position in sedan
Wednesday, July 27, 2011 8:03 AM
if you cant fit a ported, then you certainly wont fit a tline and OBVIOUSLY wont fit a 6th...




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Re: sub and port firing position in sedan
Wednesday, July 27, 2011 8:16 AM
i will go with 1 driver
Re: sub and port firing position in sedan
Wednesday, July 27, 2011 11:07 AM
Anton Miller (PPC) wrote:im in agreeance for the most part. when it comes to the room to pressurize then yes, sealing would make it smaller, but it also changes the acoustics of the vehical. really comes down to listening position, not how much air to pressurize. im going off experience when i say you will get cancelation by sealing the trunk off or firing completely forward. every single sealed trunk build ive seen is about 1 db louder with the trunk open due to cancelation. it always plays the high notes WAY more promently and the flatness just isnt there. now this is what ive seen. ive seen them tuned low, ive seen them tuned high. they both sound the same, very peaky...
quote]



sounds like your talking spl there. you never judge sound quality with the trunk open. if you want sound quality your not going to ever have the highest db around. and lets be real. no one can hear the diffrence in 1 db. only the meter can read it. so again. not really applicable unless your building a spl competition setup. and if you are u can throw sound quality out the window.

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