# "sub placement" does it matter?



## Jcube69 (Jan 15, 2009)

currently my system consists of

pioneer 800prs
kenwood x1200m (sub amp) (gain 60-75%)
kenwood kac-x4r (sound amp) (gain ~50% mids and tweets together 6x9s seperate channel)
stock 6x9s tweets and door 
2 12" dayton mk III's
custom slot port box tuned 33-36hz (i hope cant really test it...), port and drivers on the same side

currently i have my box flush up gainst my back seat with the subs firing towards the seats (like3-4 inches, if that, of room between subs and seat and they do not fold down)
*
would that effect the dbz or sound of my subs? *

i had them firing towards my trunk for a few hours after i built the box butt when system was cranked up i think the pressure from the port and drivers was deflecting off the back of the trunk and pushing the drivers in causing them to bottom out (i hear a loud like buzz clack rattle thing)

when i put them facing my seat i did not get this noise but idk if it sound quite the same.....they do hit hard but you cant really hear them out side of the car (and yes i know you dont nessesarly want that but for the amount of power goign into those things they should not be that quite outside the car with no dampening -.-)

i've always been worried about bottoming out my subs but since i've never actually heard a sub bottom out i cant guarantee this is what they are doing (for all i know it could just be my trunk lid or spoiler flaping around)

*to wrap it up.....
does the placement effect my subs much?

and is what im hearing really my subs bottoming out?*


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## Jcube69 (Jan 15, 2009)

any one want to comment? ideas? opinions?


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## cmayo117 (Aug 14, 2009)

Ok, where to start... Yes, It definitely does affect sound and spl but it is very unlikely that it's causing your subs to bottom out; only to much power will do that. Read this. It's a pretty good and easy to understand explanation of subwoofer placement. 

The loud cracking noise your hearing could be from the subs bottoming out or it could be from your trunk rattling or some other source. What exactly does it sound like? Does it look like the subs are moving too far? deadening your trunk would probably help; I know mine rattled like crazy before I deadened it. Look up Second Skin and Sound Deadener Showdown. Both sites offer great products and they are both very informative.


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## w8lifter21 (Jun 12, 2009)

Good read cmayo117!


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## Jcube69 (Jan 15, 2009)

cmayo117 said:


> Ok, where to start... Yes, It definitely does affect sound and spl but it is very unlikely that it's causing your subs to bottom out; only to much power will do that. Read this. It's a pretty good and easy to understand explanation of subwoofer placement.
> 
> The loud cracking noise your hearing could be from the subs bottoming out or it could be from your trunk rattling or some other source. What exactly does it sound like? Does it look like the subs are moving too far? deadening your trunk would probably help; I know mine rattled like crazy before I deadened it. Look up Second Skin and Sound Deadener Showdown. Both sites offer great products and they are both very informative.


it sound like there moving to far in and hitting the magnet. a loud metal on metal flaping crack distotion sound? starts out like a static pop but then increases..not sure how to explain it....on hard hitting low notes (like linkin park lying from you near the begining)

\
but when my subs were facing the rear (trunk lid) and i opened the trunk i could turn my deck up max (even gain 90% i dont like gain any higher though) without hearing anything damaging and feeling the extremly high port velocity blowing my shirt...


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## Jcube69 (Jan 15, 2009)

and that read on placement helped alot i will definitly trypostition i would have never tried before (subs firing at the trunk against the rear for instance...)


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## cmayo117 (Aug 14, 2009)

So, the only time you hear the sound is when the subs are facing the rear and the trunk is closed? It sounds to me like something is rattling on your trunk, possibly your license plate. I honestly don't have a lot of experience bottoming out subs either, but the only way I know to describe it is more of a plastic sound rather than metal rattling on metal. 

Also, what do you have the infrasonic filter set to on that amp? If it's set at too low a frequency, turning it up could help keep your subs from bottoming out.


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## Jcube69 (Jan 15, 2009)

cmayo117 said:


> So, the only time you hear the sound is when the subs are facing the rear and the trunk is closed? It sounds to me like something is rattling on your trunk, possibly your license plate. I honestly don't have a lot of experience bottoming out subs either, but the only way I know to describe it is more of a plastic sound rather than metal rattling on metal.
> 
> Also, what do you have the infrasonic filter set to on that amp? If it's set at too low a frequency, turning it up could help keep your subs from bottoming out.


by plastic sound i assume u mean like a wobbeling sweep sound (if u took a big metal sheet and bent it in and out)...i've heard that before but i know that is over excursion....then again i've never heard a "true" bottoming out sub in person. just heard it sounds like a clack (and u tube doesnt have good quality audio..)

no way is this my license pl8 this sound is LOUD and it starts of small if i use a bass test cd it really gets going

i do here it with the subs facing the seats but i have to crank the system alot higher (funny thing is is they are closer to the back of the seats (like 3-4 inches) then the back of the trunk (3ft ish)

as for my infrasonic this is the reason why i felt it should not be bottoming out i have it set at 26 higher then my graphic models called for (i have like 3-4mm excursion clearence even at 23hz at full power with 8% buffer zone...) and i have turned it up to 40hz to test it...when subs pound hard enough same result


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## Jcube69 (Jan 15, 2009)

i could turn the box around and have like 2-3 ppl sit on my trun after i take off my license pl8 to see if it fixes anything

itl have to get warmer though -40 is a bit to cold to do that with...

o and i have though it could be my rear seat as when i have had back passengers in the pass ive noticed it doesnt sound as loud....hmm ill have to stuff foam around that too..........

sorry i could probably figure it out on my own but i like input for confirmation and when i type i have insights ididnt think of before....

that bass placement read was very good though! i've been trying to find somthing on that for awhile tbh


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## T3mpest (Dec 25, 2005)

Jcube69 said:


> by plastic sound i assume u mean like a wobbeling sweep sound (if u took a big metal sheet and bent it in and out)...i've heard that before but i know that is over excursion....then again i've never heard a "true" bottoming out sub in person. just heard it sounds like a clack (and u tube doesnt have good quality audio..)
> 
> no way is this my license pl8 this sound is LOUD and it starts of small if i use a bass test cd it really gets going
> 
> ...



It stops happening because your putting them closer to your back seat instead of away toward the trunk. When you put them near your seats they are within 4 inches of the seat. The pressure the subs are creating is initially pressurizing a very small area, keeping a bit of pressure on the cones. This pressure is keeping the cones from moving too far and bottoming out. In a trunk car facing the trunk lid is almost always louder. In additon, if you can get it very close to thei lid (3-4 inches like you do when facing the other way) you'll create another loading wall (the actual term for when you put a sub next to a boundary to stop overexcursion). That's probably your best bet. The other good SPL option in a trunk is to face towards the seat, but seal off behind the woofer, its' alot more work for a minimal gain.


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## Jcube69 (Jan 15, 2009)

T3mpest said:


> It stops happening because your putting them closer to your back seat instead of away toward the trunk. When you put them near your seats they are within 4 inches of the seat. The pressure the subs are creating is initially pressurizing a very small area, keeping a bit of pressure on the cones. This pressure is keeping the cones from moving too far and bottoming out. In a trunk car facing the trunk lid is almost always louder. In additon, if you can get it very close to thei lid (3-4 inches like you do when facing the other way) you'll create another loading wall (the actual term for when you put a sub next to a boundary to stop overexcursion). That's probably your best bet. The other good SPL option in a trunk is to face towards the seat, but seal off behind the woofer, its' alot more work for a minimal gain.


my only problem with all that is shouldnt it bottom out with the trun lid open then? idk if you had read the prevous post i mentioned that because if they face the trun with the back of the box at my seats they dont bottom out or over excured


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## cmayo117 (Aug 14, 2009)

Jcube69 said:


> my only problem with all that is shouldnt it bottom out with the trun lid open then? idk if you had read the prevous post i mentioned that because if they face the trun with the back of the box at my seats they dont bottom out or over excured


Yeah, that doesn't make any since. That's why I was thinking it was something rattling.


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## Jcube69 (Jan 15, 2009)

cmayo117 said:


> Yeah, that doesn't make any since. That's why I was thinking it was something rattling.



wow i read my quote and felt so bad -.- damn typos>.<
like i said its confusing the ratteling is so strong and loud and increases with sub power i assumed it was the subs...guess ill need to experiment a bit ^.^


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## cmayo117 (Aug 14, 2009)

Jcube69 said:


> wow i read my quote and felt so bad -.- damn typos>.<
> like i said its confusing the ratteling is so strong and loud and increases with sub power i assumed it was the subs...guess ill need to experiment a bit ^.^


I meant it doesn't make any since that it would go away when you open the trunk if it's coming from the subs bottoming out. But yeah just mess around with it more and try to figure out where the noise is coming from. Be careful not to blow your subs though.


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