ok... guys i need some help here...
the box turned out how i planned, and should sound good. but just doesnt perform where i want it to. it hits way to low andsounds like it cant hit any higher than 50hz. i expected to lose a lot of upper bass but this is just stupid. ive done my math over and over. maybe someone can double check my work.
internal dementions-
14.6x16.6x14.25 (3126.91in3)
port-
4inch port, 6.5 inches in the box. (326.72in3)
thats 3126.91in3 in each chamber.
or 1.8cuft which is what i planned.
but i cant figure out why the response curve is the way it is.
-Drew
(the LPF is around 70)
BUILD PIX
http://i40.photobucket.com/albums/e216/saxwonder05/subs1-1.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/subs2.jpg
Replies (32)
Victor on 03/2/2007 02:56:58
What subs are u using by the way????
I had a similar install done, am sure swez remembers the pictures i had sent him..
Probably you went wrong in calculating the box volume.. not the math, but the acoustic response of your subs in a bigger sized box..
One thing is sure that its the tuning of the box and not of the sub that needs to be considered when doing ported boxes...
BUT one cant forget the optimum volume that can be used with a particular sub... T/S specs of a sub guide us here...the manufacturer usually gives you the suitable internal volume of the enclosure, and its not advisable to deviate drastically from the given volume..until and unless you are a pro at designing enclosures and know for sure what you are in for..
+/- 0.25 cu ft deviation also changes the response curves by a huge extent..
can u give the model number and specs of the subs you are using..????
Victor...
P.S : of what I see now , there are a few things you can try..
1 - turn up the LPF to around 100Hz
2 - try putting in some heavy object that wont move .. inside each enclosure to occupy some volume... it cud be a block of wood or say 3/4" mdf sheets or anything else that occupies the internal space and decreases the internal volume ur sub wud get..
3 - I am leaning towards a diagnosis that the enclosure is much bigger than the size required. There seems to be a huge bump somewhere below 50Hz and a sudden roll-off after that.. so that makes the low freq sound too prominent..If it was for HT purpose such a response wud be good .. but for car audio One needs a much more flatter response..
4 - after you experiment in this manner... we shall recalculate the box for you and tell u how much exactly you need to cut on the internal volume.. then u can have a permanent solution to it..
5 - Also if you change the internal volume of the box, the port tuning wud change, so lter probably you would need to change that too..
6 - Before you finalise the install its advisable to do this exercise..
newB on 03/2/2007 03:52:27
the subs are Infinity Kappa Perfect 12.1s
(not VQ)
they are recomended 1.75 and i built mine to 1.8.
i will experiement with the solid object inside the box, also would shortening my port change the response curve?
my new bxi1600d should be here tomorrow... we'll see how that goes.
another secondary question, would a very soft suspention be due to to much power???
-Drew
Victor on 03/2/2007 04:18:33
Dude... your math is wrong too..
that is a 2 cuft internal volume...
here is the calculation
14.6x16.6x14.25 = 3453.63 cu in
devide that by 1728 = 1.998628 cu ft...
the port volume
is Pie x radius squared x height
the diameter of the port is 4 " hence the radius is 2"
= 3.14 x (2)(2) x 6.5 = 3.14 x 4 x 6.5 = 81.64 cu in
ie. 0.047 cu ft..
one more thing,, u have calculated only the portlength that goes into the box... what about the part of the port that stays outside.. that needs to be calculated too while deciding the port tuning frequency....
Victor
If you are taking about the softness of ur cone suspension , when u push it in , has nothing to do with this.. it simply means your sub has a higher sensitivity rating and will move in and out easily with lesser power, meaning higher spl at lesser power..
PS; according to the subwoofer manual by the manufacturer, that sub needs a 1.75 cuft enclosure which includes the port displacement as well as the sub displacement...
that means that you actually need to reduce the internal volume of the box.. like this...
As per the present status...
Net internal volume of the enclosure = 1.998 cuft...
Port displacement inside the box = 0.047 cuft...
Sub displacement = will stay the same in both the case , so we shall not consider this here..
ie. 1.998 - 0.047 = 1.951
now as per the manufacturer this value shud be
1.75 cuft - 0.0897 cuft = 1.663 ( here the full port is inside the box ie. 12.33 x 4 x 3.14)
comparing both the values.. you need to displace
1.951 - 1.663 = 0.288 cuft of volume inside your box with some solid object
newB on 03/2/2007 04:35:07
i used a port length calcuator for the port, its 12.3 inches long to tune to to 32hz with a box of 1.8 (im pretty sure)
i squared the diameter not the radius thats my mistake.
so i should put .25 cuft into the box?
would that make the tuning frequency between 32-35hz?
-Drew
Victor on 03/2/2007 04:51:36
i re-edited the previous reply, please read that, and its a matter closed. your problem wud be solved.. rest all is ok with this enclosure..
mdf pieces are recommended..
dimensions of the pieces will depend on the thickness of wood, please recheck the exact dimensions and volume of those pieces before u install them permanently inside the box..
newB on 03/2/2007 05:02:45
sounds wonderful
this site has always been my "last resort" site because you guys can help anyone and im confident that when situations like this come up you guys will be there. your help is very much appreciated. i remember this was the first forum i joined online back when i wanted to buy the (2) 12inch Audiobahn setup for 200$ all prefab. ive come along way and its mostly due to forums such as this. your effect on the audio world is more than you know.
im picking up my paycheck tomorrow, how do i donate again?
-Drew
Victor on 03/2/2007 05:19:45
Its always a pleasure to be on CK, wether you are helping or being helped.. SMILE...
donations are a department handled by swez and walt... they can guide you here.
also a request to you and all the others whom CK has helped with the audio systems, it woudl be great if you follow the post with a feedback and a result of the help.. It would be a higher boost of morale than jsut saying thanks..
Thanks for helping us help you. The donation will be great to keep this site running the way it is and impove too.
Victor...
newB on 03/2/2007 05:33:59
yeah i will have my bxi1606 and smaller internal volume by early next week, will update with pix and maybe a vid.
and i'll try to get ahold of swez soon.
-Drew
jamesp on 03/2/2007 08:11:01
newB, I have a touch of dyslexia so I used to occasionally forget to determine the square of the radius and square the diameter instead. I use the formula below to keep myself straight.
Ex. if you put a 4" dia. circle inside a 4" square, it will occupy .785 of the space in the square. The remaining .215 of the space is in the corners of the square. A 4" square has an area of 16in², a 4" circle has : 16in²x.785=12.26in²
Since ¶/4= .785, the formula, ¶/4 x diameter² x height gives the same result. You can use .785 as a constant and not convert diameter to radius. The circle in a square image just helps me visualize what is really happening. so if the diameter= 4" and the height = 6.5"then:
(.785) (4)² (6.5)= 81.64in³
I dont know if this will help you but I find it a bit less confusing to my often muddled brain GRIN
swez on 03/2/2007 14:13:06
If you wish to donate via PayPal, just hit the donation button at the bottom of this page.
If paying by personal check, go down to the large green box and click on "Privacy Policy". That will give you Walt's address.
Swez
Victor on 03/3/2007 13:29:32
The basic idea , when converting a round port to a squared port is to maintain the cross sectional area of the port..the length of the port remains same... also the total volume of the port remains same...
tho there is one more factor that comes into play and that is port velocity..
Altho here in newb's case he is using round ports so he shudnt have an issue with it....
Victor on 03/3/2007 13:46:27
just to make sure you dont make any mistakes while calculating the volume of the mdf pieces you put in..
ex.
if you decide to put in mdf sheet of 3/4" ...and dimension of 14.6"x14.25"
the total volume of that piece would be 14.6x14.24x0.75 = 156.04 cu in.
devide that by 1728 ... hence 156.04/1728 = 0.0903 cu ft
putting in 3 such pieces will give u a total volume of 0.271 cu ft , this should get you just close to the required 0.288 cu ft....
by the way, u have really made a much bigger box than the sub requires...
one of the dimensions would have been 2.5" smaller ... and thats a lotta space in sedans and smaller cars.. the depth of your sub enclosure could have been 2.5" lesser and you cud have got a larger boot space....
one really needs to plug in the right numbers before building a system..
anyways,, one always learns with experience, i am sure the next time u do a system , you would never make this same mistake again...
dont we all learn....?
Victor...
PS: dont forget to seal all the edges and joints with silicon sealant.... you will need to insure any and all air leakages...
If you can get some sound damping material, sheets or paint, a layer of either lining the interiors of the box would be a good option to avoid internal resonance of the enclosure..
you can even apply a single layer of fibre glass mat and resin , it shall work both as a sealant and a sound dampner...
newB on 03/3/2007 16:45:27
yeah i sealed all the internal edges and put 1lb of polyfill for every 1cuft of internal airspace. the build itself came out ALMOST to plan, it was internally supposed to be only 13.5inches high but ended up 14.25 due to a mistake when i lay'd out all the pieces.
-Drew
cplkittle on 03/3/2007 20:58:51
Is there any difference in bass frequencies (not volume) when the seat is in the vehicle v/s when it is out or laid down?
Most of the time you want the port on the same side as the sub.
Try seat up v/s seat down and also try covering the ports with your hand to block them off and see if there is any difference.
Victor on 03/3/2007 23:24:39
you dont need the polyfill here, the polyfil is to give the woofer a false impression of a larger internal space, where as in your case you already have a larger internal volume than required. putting polyfill will make the woofer feel even a larger internal space..
try removing it, and instead use some sound damping material like asphalt-butyl based sheets, or damping paste , or fibreglass the internals of the enclosure with a single layer...
Victor...
ShootuhMcBustaCap on 03/4/2007 10:24:03
Nice looking box though. I love the original Perfect sreies, I had a 10.1DVC for a while in a huge ported box, and it seemed to have the same problem. Unfortunately, this was before the days that underpowering and clipping came to my knowledge, so it live was short lived, and it was replaced with a Reference 1042D. Nice setup man! I love Infinity.
Have you fried facing the subs rearward in your trunk? Personally, I found it to be the only fix at my knowledge at the time, and personally I think it works well for pretty much any subs.
newB on 03/4/2007 16:12:40
i was thinking about that.... try bouncing the waves off the trunk, i liked the sound better with my sealed setup. the problem now is that the box is semi-perminent. to move it have to break the seal on the ports loose and push them back into the box to slide it out. when i added my cube to fill the internal volume, i pulled out a lot of the polyfil. next time im in to add a brace i'll pull most and just leave some in the corners.
it sounds much better with the cube(s)
but im afraid now im getting voltage drop and my alt cant handle the load....... even with the red-top.
=/
-Drew
Victor on 03/4/2007 21:44:48
What amps are you using.. and what is the alt capacity??? do u have the big 3 done??? are the gains set properly???
is the SSFilter on..?? have you sound damped the car??
these are all relavant questions to lead u to a good install....
that sub amp u are using has 25 x 3 fuses ie. a max of 75 amperes current draw, whats the draw on the amp u are using to power the full range speakers...
the first thing to do here is go back a bit on the gains and see if the sound is good enuf and if the major dimming can be eliminated.
if the dimming goes and the sound is unsatisfactory the you may wanna do the big 3 upgrade.
what is the idel speed set at present?? try pitching it up a bit say, @1000 rpm and see if there is a difference in the system performance and ligh dimming..just check and set it back to a normal idel speed.
after doing this if things imporve as expected, then u can shorten the alternator pulley to make the alt work efficiently better at idel speed...
this should solve most of your problems, but if still things dont improve then you may wanna opt for a new alternator..
A good 150 amp alt should do the trick.
SSFilter on the sub amp filters out frequencies below the tuning frequency of the sub system.. this saves the subs from being harmed and saves the amp a lot of hardwork to produce frequencies that are not going to be heard... one needs to set the SSFilter a tad bit lower than the port tuning freq of the sub.
In your case you can set it at 30Hz.
Sound Damping the car is very essential for any good car audio install. it helps eliminate all the rattles, and helps avoid the flexing of the sheet metal in car and in turn increases the SPL inside the listening area by concentrating the sound waves inside...distortion free sound and higher SPLs....
Victor...
newB on 03/5/2007 01:48:25
alright lets see if i can address all those...
im using
1) DHD power cruiser 200+200 2ch. amp for interiors (four Infinity coaxials)
2)Bxi1600d for subs (two 80 amp fuses)
it is a 75amp alt but besides the system there are practicly no electronics in the car (windows locks ext)
gain on the interior amp is 1/4
gain on sub amp is 3/5
8ga. ground on interior and 4ga ground from sub amp.
4 ga main power into 4 8ga. runs (one to interior amp, three to sub amp)
SSfilter is ~25 i think.
(i'll move that up a bit)
sound dampening is fairly minimal.
ive foamed the trunk and filled the interior rear-quarter panel with extra polyfill and it actually made a big difference.
that and i got rid of little things like gas cap and lisense plate rattle.
UMmmmmm..... i also upgraded the alt to bat by adding with an extra run of 10ga. and upgraded the bat ground to 4ga straight to the engine bay.
did i miss anything??
-Drew
Victor on 03/5/2007 02:01:22
Bxi1600d is this the hifonics brutus u are talking about.. if yes then the owners manual says its got 25amps x 3 fuses..
what are the fuses on the DHD amp.....
u surely need an alt upgrade if ur present alt is jsut a megre 75 amps...
newB on 03/5/2007 02:03:47
yeah it has two 80s
and one 25 on the DHD
and it is the hifonics brutus 1600
-Drew
Victor on 03/5/2007 02:43:29
it is highly advisable to get a new 200amp HO alt, get a shortened pulley done on it and do the big 3 upgrade with 0/1 guage wiring.. rest all seems to be ok with your setup
probably after ur alt is done , the subs gonna bump much more when ur amps get full power... so u will need to use some damping mats or paint instead of the polyfill to add some weight to the sheet metal of ur car..
Victor...
newB on 03/5/2007 02:48:44
yup!
i think the estimate i got online for an alt for my car was ~200$ for a bigger alt.
i think it was around 175amps but i can bump it up a bit
-Drew
newB on 03/5/2007 23:42:51
dont have much time now.
the internal volume wasnt the cuplrit, but box flex. some additional braces fixed it and now its the system i planned it to be weeks ago.
-Drew
PS. the suspention disconnected from my VC.
but who needs a suspention anyways???SMILE
newB on 03/6/2007 01:51:28
http://i40.photobucket.com/albums/e216/saxwonder05/audio/blacklabel.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/boom1.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/boom2.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/car1.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/ports.jpg
i-Drew/i
newB on 03/7/2007 01:28:16
???
comments concerns?
-Drew
Victor on 03/7/2007 02:35:37
am glad you built urself a satisfactory system..
just one comment.. since you are learning certain thigns can be excused. but one needs to be more precise and neat while doing a car audio install.
i still cant make out what suspension are you talking about..???? can u take pics and post em too..
Victor...
Ps: Integrity of the enclosure is always the first concern, flexing and leaking needs to be checked..
but hey it doesnt mean that internal volume is not the culprit.. dont over look that .. try coming close to the actual volume required and you shall see the difference in the clarity of bass, the transients and crispness.....
It is suggested to have those blocks inside to occupy the extra volume. Rest you are the best judge for the system you enjoy listening to.
newB on 03/7/2007 02:54:09
yeah it was just a mistake on my part.
it sounds mucho better and yeah i left the cubes in. and im still gunna put some polyfil in the corners.
im talking about the spider under the cone of the sub.
its no longer glued to the VC.
so i think the only thing stopping the cone from hitting the back of my head is the surround........ =/
-Drew
Victor on 03/7/2007 03:34:54
quit the polyfill idea... just let it be the way it is.. polyfill is generally used where ther eis not enuf space to provide the sub a proper sized enclosure, the polyfill makes the sub believe that its in a bigger enclosure by slowing down velocity of a rear wave reflecting from walls of the enclosure inside it..
when in such a case where an enclosure is bigger than the required size one doesnt need polyfill and using it can give unwanted results in sound. probably untrained ears wont be able to make out a difference in the presence and absence of polyfill....
Instead just re-insure the flex strength and all joints , seal them with silicon sealent and if you are too bent on putting something inside the box then use any brand of sound damping mat on the inside walls of the enclosure..
ShootuhMcBustaCap on 03/7/2007 05:02:18
Pertty smooth install there. I wish I could go all out custom like that, but the title isn't in my name yet, so rear deck sound ports are out of question.
I have done a very similar install to this, but with a Toyota Cressida, an Single Infinity 10, and a bandpass box. Looked quite similar to that, but with a much shorter port protrusion from the rear deck.
I have to ask, are there any port noise issues with that setup? My Cressy's setup to the untrained ear sounded awesome, but I could hear a gale force wind coming from that port. Still much better than losing all the effiecency to the trink lid and back seat, but annoying as hell. I tried using a different size port and it helped a little but couldn't be fully cured.
newB on 03/7/2007 21:49:51
the only reason ive kept a slight idea on the polyfil was because of standing waves but hey, im not 100% sure thats just what ive heard.
i would take pix of the spider not connected to the VC but for now the magnets are in the box.
no port noise from these.
ive done two ported boxes one with 2inch ABS and this with 4inch ABS on both installs i just used a good medium corse file and rounded the inner edgel out, and what was left was slightly rough. no problems as far as port noise. even when i put my head right next to the port.
-Drew
ShootuhMcBustaCap on 03/8/2007 06:51:13
Nice. But I am keeping in mind mine was an bandpass, so port velocity was nuts. It also reflected right off my back window, and straight to my head. Nobody else really noticed it though. When I put the sub in my Sentra's trunk, with the backseat folded down, it was no longer an issue. Eitheir way it was still nice. But I would trade in a second for some ported Perfect 12.1s.
the box turned out how i planned, and should sound good. but just doesnt perform where i want it to. it hits way to low andsounds like it cant hit any higher than 50hz. i expected to lose a lot of upper bass but this is just stupid. ive done my math over and over. maybe someone can double check my work.
internal dementions-
14.6x16.6x14.25 (3126.91in3)
port-
4inch port, 6.5 inches in the box. (326.72in3)
thats 3126.91in3 in each chamber.
or 1.8cuft which is what i planned.
but i cant figure out why the response curve is the way it is.
-Drew
(the LPF is around 70)
BUILD PIX
http://i40.photobucket.com/albums/e216/saxwonder05/subs1-1.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/subs2.jpg
Replies (32)
Victor on 03/2/2007 02:56:58
What subs are u using by the way????
I had a similar install done, am sure swez remembers the pictures i had sent him..
Probably you went wrong in calculating the box volume.. not the math, but the acoustic response of your subs in a bigger sized box..
One thing is sure that its the tuning of the box and not of the sub that needs to be considered when doing ported boxes...
BUT one cant forget the optimum volume that can be used with a particular sub... T/S specs of a sub guide us here...the manufacturer usually gives you the suitable internal volume of the enclosure, and its not advisable to deviate drastically from the given volume..until and unless you are a pro at designing enclosures and know for sure what you are in for..
+/- 0.25 cu ft deviation also changes the response curves by a huge extent..
can u give the model number and specs of the subs you are using..????
Victor...
P.S : of what I see now , there are a few things you can try..
1 - turn up the LPF to around 100Hz
2 - try putting in some heavy object that wont move .. inside each enclosure to occupy some volume... it cud be a block of wood or say 3/4" mdf sheets or anything else that occupies the internal space and decreases the internal volume ur sub wud get..
3 - I am leaning towards a diagnosis that the enclosure is much bigger than the size required. There seems to be a huge bump somewhere below 50Hz and a sudden roll-off after that.. so that makes the low freq sound too prominent..If it was for HT purpose such a response wud be good .. but for car audio One needs a much more flatter response..
4 - after you experiment in this manner... we shall recalculate the box for you and tell u how much exactly you need to cut on the internal volume.. then u can have a permanent solution to it..
5 - Also if you change the internal volume of the box, the port tuning wud change, so lter probably you would need to change that too..
6 - Before you finalise the install its advisable to do this exercise..
newB on 03/2/2007 03:52:27
the subs are Infinity Kappa Perfect 12.1s
(not VQ)
they are recomended 1.75 and i built mine to 1.8.
i will experiement with the solid object inside the box, also would shortening my port change the response curve?
my new bxi1600d should be here tomorrow... we'll see how that goes.
another secondary question, would a very soft suspention be due to to much power???
-Drew
Victor on 03/2/2007 04:18:33
Dude... your math is wrong too..
that is a 2 cuft internal volume...
here is the calculation
14.6x16.6x14.25 = 3453.63 cu in
devide that by 1728 = 1.998628 cu ft...
the port volume
is Pie x radius squared x height
the diameter of the port is 4 " hence the radius is 2"
= 3.14 x (2)(2) x 6.5 = 3.14 x 4 x 6.5 = 81.64 cu in
ie. 0.047 cu ft..
one more thing,, u have calculated only the portlength that goes into the box... what about the part of the port that stays outside.. that needs to be calculated too while deciding the port tuning frequency....
Victor
If you are taking about the softness of ur cone suspension , when u push it in , has nothing to do with this.. it simply means your sub has a higher sensitivity rating and will move in and out easily with lesser power, meaning higher spl at lesser power..
PS; according to the subwoofer manual by the manufacturer, that sub needs a 1.75 cuft enclosure which includes the port displacement as well as the sub displacement...
that means that you actually need to reduce the internal volume of the box.. like this...
As per the present status...
Net internal volume of the enclosure = 1.998 cuft...
Port displacement inside the box = 0.047 cuft...
Sub displacement = will stay the same in both the case , so we shall not consider this here..
ie. 1.998 - 0.047 = 1.951
now as per the manufacturer this value shud be
1.75 cuft - 0.0897 cuft = 1.663 ( here the full port is inside the box ie. 12.33 x 4 x 3.14)
comparing both the values.. you need to displace
1.951 - 1.663 = 0.288 cuft of volume inside your box with some solid object
newB on 03/2/2007 04:35:07
i used a port length calcuator for the port, its 12.3 inches long to tune to to 32hz with a box of 1.8 (im pretty sure)
i squared the diameter not the radius thats my mistake.
so i should put .25 cuft into the box?
would that make the tuning frequency between 32-35hz?
-Drew
Victor on 03/2/2007 04:51:36
i re-edited the previous reply, please read that, and its a matter closed. your problem wud be solved.. rest all is ok with this enclosure..
mdf pieces are recommended..
dimensions of the pieces will depend on the thickness of wood, please recheck the exact dimensions and volume of those pieces before u install them permanently inside the box..
newB on 03/2/2007 05:02:45
sounds wonderful
this site has always been my "last resort" site because you guys can help anyone and im confident that when situations like this come up you guys will be there. your help is very much appreciated. i remember this was the first forum i joined online back when i wanted to buy the (2) 12inch Audiobahn setup for 200$ all prefab. ive come along way and its mostly due to forums such as this. your effect on the audio world is more than you know.
im picking up my paycheck tomorrow, how do i donate again?
-Drew
Victor on 03/2/2007 05:19:45
Its always a pleasure to be on CK, wether you are helping or being helped.. SMILE...
donations are a department handled by swez and walt... they can guide you here.
also a request to you and all the others whom CK has helped with the audio systems, it woudl be great if you follow the post with a feedback and a result of the help.. It would be a higher boost of morale than jsut saying thanks..
Thanks for helping us help you. The donation will be great to keep this site running the way it is and impove too.
Victor...
newB on 03/2/2007 05:33:59
yeah i will have my bxi1606 and smaller internal volume by early next week, will update with pix and maybe a vid.
and i'll try to get ahold of swez soon.
-Drew
jamesp on 03/2/2007 08:11:01
newB, I have a touch of dyslexia so I used to occasionally forget to determine the square of the radius and square the diameter instead. I use the formula below to keep myself straight.
Ex. if you put a 4" dia. circle inside a 4" square, it will occupy .785 of the space in the square. The remaining .215 of the space is in the corners of the square. A 4" square has an area of 16in², a 4" circle has : 16in²x.785=12.26in²
Since ¶/4= .785, the formula, ¶/4 x diameter² x height gives the same result. You can use .785 as a constant and not convert diameter to radius. The circle in a square image just helps me visualize what is really happening. so if the diameter= 4" and the height = 6.5"then:
(.785) (4)² (6.5)= 81.64in³
I dont know if this will help you but I find it a bit less confusing to my often muddled brain GRIN
swez on 03/2/2007 14:13:06
If you wish to donate via PayPal, just hit the donation button at the bottom of this page.
If paying by personal check, go down to the large green box and click on "Privacy Policy". That will give you Walt's address.
Swez
Victor on 03/3/2007 13:29:32
The basic idea , when converting a round port to a squared port is to maintain the cross sectional area of the port..the length of the port remains same... also the total volume of the port remains same...
tho there is one more factor that comes into play and that is port velocity..
Altho here in newb's case he is using round ports so he shudnt have an issue with it....
Victor on 03/3/2007 13:46:27
just to make sure you dont make any mistakes while calculating the volume of the mdf pieces you put in..
ex.
if you decide to put in mdf sheet of 3/4" ...and dimension of 14.6"x14.25"
the total volume of that piece would be 14.6x14.24x0.75 = 156.04 cu in.
devide that by 1728 ... hence 156.04/1728 = 0.0903 cu ft
putting in 3 such pieces will give u a total volume of 0.271 cu ft , this should get you just close to the required 0.288 cu ft....
by the way, u have really made a much bigger box than the sub requires...
one of the dimensions would have been 2.5" smaller ... and thats a lotta space in sedans and smaller cars.. the depth of your sub enclosure could have been 2.5" lesser and you cud have got a larger boot space....
one really needs to plug in the right numbers before building a system..
anyways,, one always learns with experience, i am sure the next time u do a system , you would never make this same mistake again...
dont we all learn....?
Victor...
PS: dont forget to seal all the edges and joints with silicon sealant.... you will need to insure any and all air leakages...
If you can get some sound damping material, sheets or paint, a layer of either lining the interiors of the box would be a good option to avoid internal resonance of the enclosure..
you can even apply a single layer of fibre glass mat and resin , it shall work both as a sealant and a sound dampner...
newB on 03/3/2007 16:45:27
yeah i sealed all the internal edges and put 1lb of polyfill for every 1cuft of internal airspace. the build itself came out ALMOST to plan, it was internally supposed to be only 13.5inches high but ended up 14.25 due to a mistake when i lay'd out all the pieces.
-Drew
cplkittle on 03/3/2007 20:58:51
Is there any difference in bass frequencies (not volume) when the seat is in the vehicle v/s when it is out or laid down?
Most of the time you want the port on the same side as the sub.
Try seat up v/s seat down and also try covering the ports with your hand to block them off and see if there is any difference.
Victor on 03/3/2007 23:24:39
you dont need the polyfill here, the polyfil is to give the woofer a false impression of a larger internal space, where as in your case you already have a larger internal volume than required. putting polyfill will make the woofer feel even a larger internal space..
try removing it, and instead use some sound damping material like asphalt-butyl based sheets, or damping paste , or fibreglass the internals of the enclosure with a single layer...
Victor...
ShootuhMcBustaCap on 03/4/2007 10:24:03
Nice looking box though. I love the original Perfect sreies, I had a 10.1DVC for a while in a huge ported box, and it seemed to have the same problem. Unfortunately, this was before the days that underpowering and clipping came to my knowledge, so it live was short lived, and it was replaced with a Reference 1042D. Nice setup man! I love Infinity.
Have you fried facing the subs rearward in your trunk? Personally, I found it to be the only fix at my knowledge at the time, and personally I think it works well for pretty much any subs.
newB on 03/4/2007 16:12:40
i was thinking about that.... try bouncing the waves off the trunk, i liked the sound better with my sealed setup. the problem now is that the box is semi-perminent. to move it have to break the seal on the ports loose and push them back into the box to slide it out. when i added my cube to fill the internal volume, i pulled out a lot of the polyfil. next time im in to add a brace i'll pull most and just leave some in the corners.
it sounds much better with the cube(s)
but im afraid now im getting voltage drop and my alt cant handle the load....... even with the red-top.
=/
-Drew
Victor on 03/4/2007 21:44:48
What amps are you using.. and what is the alt capacity??? do u have the big 3 done??? are the gains set properly???
is the SSFilter on..?? have you sound damped the car??
these are all relavant questions to lead u to a good install....
that sub amp u are using has 25 x 3 fuses ie. a max of 75 amperes current draw, whats the draw on the amp u are using to power the full range speakers...
the first thing to do here is go back a bit on the gains and see if the sound is good enuf and if the major dimming can be eliminated.
if the dimming goes and the sound is unsatisfactory the you may wanna do the big 3 upgrade.
what is the idel speed set at present?? try pitching it up a bit say, @1000 rpm and see if there is a difference in the system performance and ligh dimming..just check and set it back to a normal idel speed.
after doing this if things imporve as expected, then u can shorten the alternator pulley to make the alt work efficiently better at idel speed...
this should solve most of your problems, but if still things dont improve then you may wanna opt for a new alternator..
A good 150 amp alt should do the trick.
SSFilter on the sub amp filters out frequencies below the tuning frequency of the sub system.. this saves the subs from being harmed and saves the amp a lot of hardwork to produce frequencies that are not going to be heard... one needs to set the SSFilter a tad bit lower than the port tuning freq of the sub.
In your case you can set it at 30Hz.
Sound Damping the car is very essential for any good car audio install. it helps eliminate all the rattles, and helps avoid the flexing of the sheet metal in car and in turn increases the SPL inside the listening area by concentrating the sound waves inside...distortion free sound and higher SPLs....
Victor...
newB on 03/5/2007 01:48:25
alright lets see if i can address all those...
im using
1) DHD power cruiser 200+200 2ch. amp for interiors (four Infinity coaxials)
2)Bxi1600d for subs (two 80 amp fuses)
it is a 75amp alt but besides the system there are practicly no electronics in the car (windows locks ext)
gain on the interior amp is 1/4
gain on sub amp is 3/5
8ga. ground on interior and 4ga ground from sub amp.
4 ga main power into 4 8ga. runs (one to interior amp, three to sub amp)
SSfilter is ~25 i think.
(i'll move that up a bit)
sound dampening is fairly minimal.
ive foamed the trunk and filled the interior rear-quarter panel with extra polyfill and it actually made a big difference.
that and i got rid of little things like gas cap and lisense plate rattle.
UMmmmmm..... i also upgraded the alt to bat by adding with an extra run of 10ga. and upgraded the bat ground to 4ga straight to the engine bay.
did i miss anything??
-Drew
Victor on 03/5/2007 02:01:22
Bxi1600d is this the hifonics brutus u are talking about.. if yes then the owners manual says its got 25amps x 3 fuses..
what are the fuses on the DHD amp.....
u surely need an alt upgrade if ur present alt is jsut a megre 75 amps...
newB on 03/5/2007 02:03:47
yeah it has two 80s
and one 25 on the DHD
and it is the hifonics brutus 1600
-Drew
Victor on 03/5/2007 02:43:29
it is highly advisable to get a new 200amp HO alt, get a shortened pulley done on it and do the big 3 upgrade with 0/1 guage wiring.. rest all seems to be ok with your setup
probably after ur alt is done , the subs gonna bump much more when ur amps get full power... so u will need to use some damping mats or paint instead of the polyfill to add some weight to the sheet metal of ur car..
Victor...
newB on 03/5/2007 02:48:44
yup!
i think the estimate i got online for an alt for my car was ~200$ for a bigger alt.
i think it was around 175amps but i can bump it up a bit
-Drew
newB on 03/5/2007 23:42:51
dont have much time now.
the internal volume wasnt the cuplrit, but box flex. some additional braces fixed it and now its the system i planned it to be weeks ago.
-Drew
PS. the suspention disconnected from my VC.
but who needs a suspention anyways???SMILE
newB on 03/6/2007 01:51:28
http://i40.photobucket.com/albums/e216/saxwonder05/audio/blacklabel.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/boom1.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/boom2.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/car1.jpg
http://i40.photobucket.com/albums/e216/saxwonder05/audio/ports.jpg
i-Drew/i
newB on 03/7/2007 01:28:16
???
comments concerns?
-Drew
Victor on 03/7/2007 02:35:37
am glad you built urself a satisfactory system..
just one comment.. since you are learning certain thigns can be excused. but one needs to be more precise and neat while doing a car audio install.
i still cant make out what suspension are you talking about..???? can u take pics and post em too..
Victor...
Ps: Integrity of the enclosure is always the first concern, flexing and leaking needs to be checked..
but hey it doesnt mean that internal volume is not the culprit.. dont over look that .. try coming close to the actual volume required and you shall see the difference in the clarity of bass, the transients and crispness.....
It is suggested to have those blocks inside to occupy the extra volume. Rest you are the best judge for the system you enjoy listening to.
newB on 03/7/2007 02:54:09
yeah it was just a mistake on my part.
it sounds mucho better and yeah i left the cubes in. and im still gunna put some polyfil in the corners.
im talking about the spider under the cone of the sub.
its no longer glued to the VC.
so i think the only thing stopping the cone from hitting the back of my head is the surround........ =/
-Drew
Victor on 03/7/2007 03:34:54
quit the polyfill idea... just let it be the way it is.. polyfill is generally used where ther eis not enuf space to provide the sub a proper sized enclosure, the polyfill makes the sub believe that its in a bigger enclosure by slowing down velocity of a rear wave reflecting from walls of the enclosure inside it..
when in such a case where an enclosure is bigger than the required size one doesnt need polyfill and using it can give unwanted results in sound. probably untrained ears wont be able to make out a difference in the presence and absence of polyfill....
Instead just re-insure the flex strength and all joints , seal them with silicon sealent and if you are too bent on putting something inside the box then use any brand of sound damping mat on the inside walls of the enclosure..
ShootuhMcBustaCap on 03/7/2007 05:02:18
Pertty smooth install there. I wish I could go all out custom like that, but the title isn't in my name yet, so rear deck sound ports are out of question.
I have done a very similar install to this, but with a Toyota Cressida, an Single Infinity 10, and a bandpass box. Looked quite similar to that, but with a much shorter port protrusion from the rear deck.
I have to ask, are there any port noise issues with that setup? My Cressy's setup to the untrained ear sounded awesome, but I could hear a gale force wind coming from that port. Still much better than losing all the effiecency to the trink lid and back seat, but annoying as hell. I tried using a different size port and it helped a little but couldn't be fully cured.
newB on 03/7/2007 21:49:51
the only reason ive kept a slight idea on the polyfil was because of standing waves but hey, im not 100% sure thats just what ive heard.
i would take pix of the spider not connected to the VC but for now the magnets are in the box.
no port noise from these.
ive done two ported boxes one with 2inch ABS and this with 4inch ABS on both installs i just used a good medium corse file and rounded the inner edgel out, and what was left was slightly rough. no problems as far as port noise. even when i put my head right next to the port.
-Drew
ShootuhMcBustaCap on 03/8/2007 06:51:13
Nice. But I am keeping in mind mine was an bandpass, so port velocity was nuts. It also reflected right off my back window, and straight to my head. Nobody else really noticed it though. When I put the sub in my Sentra's trunk, with the backseat folded down, it was no longer an issue. Eitheir way it was still nice. But I would trade in a second for some ported Perfect 12.1s.
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