Hi all, I know alot of you have the sub shooting thru the rear seat armrest hole so I was wondering if I could get some help and advice.

How far away are the subs from the rear seat? Is the sub/box completely sealed off from the trunk? Is there anything els I should know about this setup?

I've heard some peeps saying that this is not a good sub install position for good bass, is this true?

Here's how my install looks right now
http://www.picturetrail.com/gallery/view?uid=907460

You can get a good idea of how the box was installed and sealed off from trunk.

I know it's not a bmw but I don't know where els to go that would have expierence with this kinda rear seat ski hole install.

the sub box is completely sealed off from the trunk and the subs are about 4-5 inches apart from the rear seat.

the set up sounds OK but a bit boomy. I was wondering it there was something wrong that was done with the install.

please help, thanks

forceloader,
I fire my 12" through the armrest, and it sounds great. just tune the amp properly and you will be in good shape. My box sits 2" back from the back of the trunk so the sub doesn't hit the seat back. I have pics of how we built the car system at http://members.sounddomain.com/semisilentbob

Hope this helps,
Bob

thanks for the info

do u have the sub completely sealed off from the trunk?

How big is your sealed box? do you think a bigger box would be better for this kinda sub/box installation?

where do u have your sub crossed at? I currently have mine at 70 hertz.

is there anything els you did to the box?

'I've heard some peeps saying that this is not a good sub install position for good bass, is this true?'


no its not..its an opinion based in ignorance....i have done many and if u ask around these boards u will see i have helped design (and some completely design) a few systems with subs pointing forwards right here and they all seem to be very pleased with the setup....
Kevin

Originally posted by kevin7909
'I've heard some peeps saying that this is not a good sub install position for good bass, is this true?'


no its not..its an opinion based in ignorance....i have done many and if u ask around these boards u will see i have helped design (and some completely design) a few systems with subs pointing forwards right here and they all seem to be very pleased with the setup....
Kevin

glad to hear that kevin! I really didn't want to dis-assemble my current setup: http://www.picturetrail.com/gallery/view?uid=907460

should I change to a single sub setup? from looking at my install, Is there something I should do different to get a more solid bass?

if you look at the pics, the sub box is completely sealed off from the trunk and the subs are about 3-5 inches apart from the rear seat. the subs have 0.50 cu ft per chamber sealed box.

I have about 8-9 inches in width thru my rearseat armrest port, should that determine how big of a sub I should get? I dunno?....

any tips?

thanks

do u have the sub completely sealed off from the trunk?

How big is your sealed box? do you think a bigger box would be better for this kinda sub/box installation?

where do u have your sub crossed at? I currently have mine at 70 hertz.


Sub is sealed from trunk, we framed around it a few inches in from the pass through.

The box I use is tuned to the Adire Audio Brahma I use for SQ, and is a sealed 1.6 cu.ft box. You need to build the box to the specs of the sub you are using, sealed will be tighter, vented will be louder.

I cross the sub over at 63hz.

If you have issues with "boomy" bass, adjust the crossover point a bit. you could also invert the subs phase 180 degrees, just make sure that if you are using multiple subs that you adjust the phase of both of them not just 1.

Hope this helps,
Bob

boomy, huh?....lets start simple and work our way up to teh entire system....switch off the subs and listen to the system....is it boomy now? tune the system to sound really nice with just the midbass and tweeters.....then sit in teh driver's seat and have a friend turn up the subs gradually(assuming u dont have gain controls in the front of the car)...go up till the low bass can be felt but u cant localize it from the front...if the midbass seems to sound weird then Bob's suggestion of changing the phase is a good idea....if there seems to be a midbass hump when the subs are turned up then turn lower the subs lo-pass frequency on the x-over....after u do this and let us know how it sounds we can offer more help....actually i could add to this but i'm tired and cant bother... :)
Kevin

thanks for the info guys, I'll try to swith the phase on the subs.

tweetermanager, I noticed your using the biggest reccomended sealed box size for your 12" adire brahma; wouldn't that make it boomy? or is that ideal for subs that has no cabin gain such as an installation like ours?

I'm using the smallest reccomended sealed box size for my subs, You think maybe a bigger box would help?

again thanks for all the help.

assuming the internal volume is correct size for the subs... and not too big? u should start there then listen to kev and bob, they are right on it. kev helped tune my subs firing forwards and helped BIG time!

'for subs that has no cabin gain such as an installation like ours'

this is incorrect....if there is a cabin there will be cabin gain...the area u sit in is the cabin, not the trunk....one reason your box might be boomy is that its small...the larger the box the less boomy(the smaller the box teh higher the resonance freq and the lower the damping and as such the more the overshoot which will result in sloppier and muddier midbass if u go way small on the box) the bass and the more low frequency efficiency usually...
Kevin

Originally posted by kevin7909
'for subs that has no cabin gain such as an installation like ours'

this is incorrect....if there is a cabin there will be cabin gain...the area u sit in is the cabin, not the trunk....one reason your box might be boomy is that its small...the larger the box the less boomy(the smaller the box teh higher the resonance freq and the lower the damping and as such the more the overshoot which will result in sloppier and muddier midbass if u go way small on the box) the bass and the more low frequency efficiency usually...
Kevin


thanks kevin, do you think certain subs in different box would sound better in a rear seat sub installation like ours or it doesn't matter?

I've tried reversing the phase and that did not work.

I made sure the trunk is sealed off from the cabin by opening the trunk when I'm in the car and the bass output in the cabin is the same when the trunk is completely open or closed so I know it's sealed off good. When I open the windows I get same bass output as when the windows are closed so it's safe to rule out any install issues right?

as for the size of the box for my image dynamics IDQv.2 10" subs, I'm using the smallest reccomended box volume of 0.47 cu ft net sealed per chamber. I'm thinking maybe that maybe my problem?

could there be other possibilities? I'd like to rule out all possibilities before I decide on major changes.......It would be alot better if I could just swap out the box or even the box/sub and keep the surrounding metal and woodwork installation...

thanks for the advice

or should I just build a ported box for the subs and keep them in the same location only with a center port between the subs? Of course properly tuned.........I wonder how that would sound?

http://www.picturetrail.com/gallery/view?uid=907460

dont change anything major yet...did u follow the tuning advice a few posts up? if so what happened? also, have u tried lightly stuffing the enclosure with polyfill (pillow stuffing sold at walmart)? dont get crazy with it but there must be quite a bit in there....the strands in it slow the air down in the box so ifit is too tightly stuffed all it does it makes your box alot smaller with no advantages at all....
Kevin

Originally posted by kevin7909
dont change anything major yet...did u follow the tuning advice a few posts up? if so what happened? also, have u tried lightly stuffing the enclosure with polyfill (pillow stuffing sold at walmart)? dont get crazy with it but there must be quite a bit in there....the strands in it slow the air down in the box so ifit is too tightly stuffed all it does it makes your box alot smaller with no advantages at all....
Kevin

yeah I've tried tuning it- low passing it (90 hertz to 80 to 70 to 60 hertz) with no luck, I've also tried filling it with polyfill (lightly, medium and extra) with no luck either.

I've also double checked and resealed the inner box and double checked the seals on the screws etc, the box has no leaks.

should I build a new ported box for the IDQ's or just get a good single 10" with a good size sealed box? I dunno

:95

did u switch off the subs altogether? tell us about your front stage....does it play midbass, x-over freq, in matted doors or custom kicks, etc.?
Kevin

Originally posted by kevin7909
did u switch off the subs altogether? tell us about your front stage....does it play midbass, x-over freq, in matted doors or custom kicks, etc.?
Kevin

yes, I have a audiocontrol 3.1 eq with a subwoofer control so I have shut the subs off completely and the front stage does sound good, it's in the doors and the doors are completely dynamatted. (no custom kicks)

good midbass, crossed at 70 hertz right now.

cross em at 55 to 60 and tell me how u like em....do NOT switch subs on....if your using AC 3xs or 4xs i know switching feq's can be a pain but since u stated u changed freqs for the sub above i figured it wouldnt be that big of a deal....i am asking u to do all this so that we can rule certain things out is all..there is a method to my madness....
Kevin

Originally posted by kevin7909
cross em at 55 to 60 and tell me how u like em....do NOT switch subs on....if your using AC 3xs or 4xs i know switching feq's can be a pain but since u stated u changed freqs for the sub above i figured it wouldnt be that big of a deal....i am asking u to do all this so that we can rule certain things out is all..there is a method to my madness....
Kevin

yup, I've tried down to 60 hertz to when I tried it for my subs- no difference. (high passed at 60 and low passed at 60), same boomy sound from subs only a little weaker.

the point was not the boominess of the subs (hence having them OFF)...i wanted to see if u liked teh sound of the MIDBASS of your FRONT drivers...if u like em(tight and loud enough for u) then we can work on getting your subs to sound inline with the mids with some eq and phase tricks...but your front stage MUST be strong and to your liking....that was the point of the test...if u heard NO difference when u moved the x-over frequency around it sounds like u have phase issues...i might be wrong but we can test that as well...
Kevin

Originally posted by kevin7909
the point was not the boominess of the subs (hence having them OFF)...i wanted to see if u liked teh sound of the MIDBASS of your FRONT drivers...if u like em(tight and loud enough for u) then we can work on getting your subs to sound inline with the mids with some eq and phase tricks...but your front stage MUST be strong and to your liking....that was the point of the test...if u heard NO difference when u moved the x-over frequency around it sounds like u have phase issues...i might be wrong but we can test that as well...
Kevin

you mean phasing of the front component mids?

no....if the midbass of the front stage is strong with the sub OFF then the mids in front are in phase with each other at the drivers head location and so we can deal with the boominess of the SUBS..i wanted to be sure the mids were NOT adding to the boominess u hear....here is what i think is going on...the box for that sub is in effect too small...ok great, so where do we go from here? well the situation is not as dismal as it might first appear...the reason is this...quite a manufacturers of very hi-end systems run the subs exactly in this manner...this is to raise the resonance frequency of the sub *system* higher(sealed enclosures are in effect a second order HI-PASS filter and with the box being too small all your doing is raising that cutoff frequency higher..some eq will help straighten things out..keep reading and we will get to that)...they then use what amounts to an equalizer to bring the low bass back into the mix...what u have is a midbass hump that outweighs the cabin gain of the low frequencies(the cabin gain starts to have effect as half the wavelength of the longest wave that can fit inside the cabin of the car is being reproduced by the sub system)..so your having the cabin gain in effect working AGAINST you with your present setup..i am trying to help u alter the variables of the setup to get cabin gain on your side by going through steps with u to find about where the hump is and then i am gonna talk u through the steps on how to smoothen the bass out so u will have that SQ u obviously so desire....
Kevin

Originally posted by kevin7909
no....if the midbass of the front stage is strong with the sub OFF then the mids in front are in phase with each other at the drivers head location and so we can deal with the boominess of the SUBS..i wanted to be sure the mids were NOT adding to the boominess u hear....here is what i think is going on...the box for that sub is in effect too small...ok great, so where do we go from here? well the situation is not as dismal as it might first appear...the reason is this...quite a manufacturers of very hi-end systems run the subs exactly in this manner...this is to raise the resonance frequency of the sub *system* higher(sealed enclosures are in effect a second order HI-PASS filter and with the box being too small all your doing is raising that cutoff frequency higher..some eq will help straighten things out..keep reading and we will get to that)...they then use what amounts to an equalizer to bring the low bass back into the mix...what u have is a midbass hump that outweighs the cabin gain of the low frequencies(the cabin gain starts to have effect as half the wavelength of the longest wave that can fit inside the cabin of the car is being reproduced by the sub system)..so your having the cabin gain in effect working AGAINST you with your present setup..i am trying to help u alter the variables of the setup to get cabin gain on your side by going through steps with u to find about where the hump is and then i am gonna talk u through the steps on how to smoothen the bass out so u will have that SQ u obviously so desire....
Kevin

OK! how can I find this hump? as stated before I have a audiocontrol 3.1 eq which has 3 bands and I've tried adjusting that and it made no major difference........

I'll change the sub box or anything if I have to but I just wanna make sure that it will solve this problem...........the last thing I want happen is that I swap the box or sub and still have the same problem

again thanks for your help, it's really cool of you for helping

well u say u like the sound of the midbass from your front drivers....cool...what i wanted u to do basically was lower the frequency of the front and rear drivers till the midbass hump was gone from the subs...then u would have a pretty good idea where it is...if u have access to a radio shack SPL meter and a test tone CD this would be a much more efficient excercise....well....just a test tone CD...tell ya what....go to your favourite CD store and buy bass meckanik CD...or any CD with test tones from 20hz to 100hz(more is better but for this situation i think thats all u need)...then use the CD and play every tone..when u get to the frequency that sounds louder than the rest u have the problem area....using the SPL meter just makes this a more efficient excercise since u can plot teh points on a graph and have a frequency response readout of your car's stereo system from wherever u place the mic (with bass it doesnt matter really where its placed)....
Kevin

no problem...i am leaving changing ANYTHING as a last resort...
Kevin

if all this doesnt help and u have time later then maybe on my way home from work i'll call u and we can play with it while i talk u through things to try....i have a hour and a half drive every evening with nothing to do but avoid accidents... :)
Kevin

OK, I'll try the test tones cd but then what should I do? I'm affraid your gonna get frustrated to! :)


I've tried just about everything, from your expierence what was the best sounding sub and box enclosure for this sub setup behind the rear seats? Maybe I should just swap out to what's already been tried and tested for this kinda install? (about 500 clean watts)

I can just sell my IDQ subs/box.

the IDQ sub is still one of the best subs u can use for SQ..the IDQ just dont get as loud as some of the newer super hi-excursion subs...if SQ is your bag then keep those subs...i am almost certain its your tuning thats amiss and not the physical setup of the system....the boxes might be too small but unless your just itching to build a bigger box for your car (it REALLY seems like you are) then just play it slow and we should find the problem area and more than likely we will be able to get better sound in your right....it may even be what your looking for...
Kevin

me get frustrated about this? this is fun to me and in the scheme of stereo issues this is about a 1 out of 10...what frustrates me is people who claim on this board/PMing and also emailing that i think i know everything when all i do here is try to help people....ya'll know who u are...
Kevin

Originally posted by kevin7909
the IDQ sub is still one of the best subs u can use for SQ..the IDQ just dont get as loud as some of the newer super hi-excursion subs...if SQ is your bag then keep those subs...i am almost certain its your tuning thats amiss and not the physical setup of the system....the boxes might be too small but unless your just itching to build a bigger box for your car (it REALLY seems like you are) then just play it slow and we should find the problem area and more than likely we will be able to get better sound in your right....it may even be what your looking for...
Kevin

OK! have u ever tried an IDQ in this kinda sub install in the rear seat ski hole?

what have you tried? subs /box, etc?

man i cant list all the stuff i have tried and heard here....it would be too long....and yes i have experience with idq in a similar setup but the box was always larger than .47cu ft....that being said...i thing the box is small BUT i think we can make it sound good the way it is....there are tradeoffs that must be made of course in the way of MAX SPL with the amps your using(even if they are 1 million watts a piece they will still need to produce more power to get the same SPL as a larger box and different tuning techniques than are gonna be required here)...but if u dont max out your amps now then its a non issue....the ski hole is not making the subs sound boomy...it does not matter where in the car the subs are located the bass response will be the same unless they are in hi-pressure zones and where yours are mounted is not one of those places in the average car....
Kevin

I've tried everything I think.........

would one or two subs make a difference? cuz one sub would fully shoot thru the port where as two subs only half the subs would shoot thru, dunno if that would make a difference.....

Originally posted by kevin7909
man i cant list all the stuff i have tried and heard here....it would be too long....and yes i have experience with idq in a similar setup but the box was always larger than .47cu ft....that being said...i thing the box is small BUT i think we can make it sound good the way it is....there are tradeoffs that must be made of course in the way of MAX SPL with the amps your using(even if they are 1 million watts a piece they will still need to produce more power to get the same SPL as a larger box and different tuning techniques than are gonna be required here)...but if u dont max out your amps now then its a non issue....the ski hole is not making the subs sound boomy...it does not matter where in the car the subs are located the bass response will be the same unless they are in hi-pressure zones and where yours are mounted is not one of those places in the average car....
Kevin

wouldn't this kinda install have the least cabin gain vs if I were to be facing the subs to the rear bumper and having it deflect back to the cabin?

cabin gain doesnt depend on reflecting the bass off a wall in the car because all your doing is COMPRESSING the air in a fixed volume...most people block off alot of the free airpath going to the cabin by pointing subs to the trunk and all the hidden gremlins come out...rear deck vibrating and trunk going crazy...will u get more cabin gain by point them to the trunk...if u read the above statements carefully u will see that i implied that u CAN have more cabin gain but then again depending on how your system is setup u may not....do me a favor and list all of your components and where the x-over settings are and which way the wires are connected (positive to positive or negative to positive)....the way u have the subs pointed now is the best way for SQ in my opinion and pointing to the trunk can only match this way IF u damp EVERY single rattle in the trunk....
Kevin

I'm having the subs custom mounted and the installer is porting through the rear "armrest". The subs will not actually face the rear seat. 2- 10" subs facing up at an angle and the the enclosure box will be ported (2 ports) through the rear armrest area. Will post results when its complete.

I'm in a little different league than most of you, but I do have a related question:

First: I'm just using an Infinity BassLink
Second: I removed the rear deck speakers because I wasn't getting any bass in the cabin. Now that the rear deck speakers are gone, I get plenty of bass, but I'm miss the rear speakers desperately.

So, I want to cut a hole in the soundproofing behind the armrest pass through. (I removed the metal punch-out when I installed the sub)... But, I don't want it to look like crap.

Finally, the question... "What can I do to cut the hole in the sound proofing without it looking like hell?"

Thanks!

the soundproofing for the ski hole is held to the large piece behind the entire seat by i think its 4 or 6 tabs...get an x-acto blade and take your time and cut it...no biggie...to have good looks? get a piece of acoustically transparent cloth the same color as your seats and stretch is across the hole and for the trun side get a piece of THICK carboard and cut a hole in it thats the same size as the ski hole...be sure to put weathstripping on the cardboard so u get no rattles...then on the other side paste acoustically transparent grey carpet...mount it like u mount the original(this si done by SCREWING the grey tabs off with your fingers..no large force necessary...easy)...there u have it....stock looking car with a nice ski hole pass through....
Kevin

Awesome.

Thanks, Kevin!

anytime....
Kevin