well i would like two kill two birds with one stone first off i have a english report due on the career of my choice and guess what i chose car audio so any websites with job descriptions would be greatly appriciated. now as to the other i have two 18" kicker compvr subwoofers in a 2.25 cu. ft. box they are rated from 2.2 to 3.3 cu .ft. and with such a large woofer i wasnt worried about low bass so i built the smallest box possible but i did not measure for the woofer displacement and the boxes are a little to small so i was thinking about flipping the woofers out the box now i do have the space i was just wondering how to wire them i thought all you had to do is wire them out of phase so they move in instead of out but im not sure
thanx alot guys,Steven
Replies (17)
swez on 10/25/2004 12:47:44
Don't do the flip routine... can damage your expensive subs as the magnets pick up everything metallic. Bad for the speaker too. (no protection.
If you have not added any polyfill or acoustical damping materials to date, try that. Your subs will deliver better low-end bass response as the damping material will give you ~10% larger enclosure. (Not physically, but acoustically)
How do the subs sound in the box now?
About your English paper, go to a few install shops like BB & CC and see if they can provide a job description for installers. You may even find this detail off BB/CC websites under employment opportunities. How easy that would be huh?
Swez
Bigeazy4387 on 10/25/2004 13:44:32
i have it with polyfill they sound fine i was just lookin for a little more low end but thanx for tha help
Victor on 10/25/2004 15:11:19
strictly no flipping the woofers..hehehehe.. of-course u can experiment if u want .. but no one around here for a while would recommend it..
if you are running it on an amp with a low pass filter try turning it on.. you may get a small bit of difference.. i fell u must be knowing this but many people forget some minute details. hence thought might just remind u..
why dont u build a new enclosue for ur woofers..??
Victor...
uochronos on 10/25/2004 15:23:04
flipping them over has far more cons then pros. cons would be risk of damageing the motor tructure of the sub from materials geating in. damage from metal being pulled into the magnet or into the motor strocture and trust me stuff well be pulled in especialy in a large speaker like this. also what is the displacment of this speaker? i cant imagine gianing alot of low end by adding that realativly small amount. the only pro i can see is you gain that small amount of space.
another option is to get 1" thick MDF and cut rings out of it. to put under the sub and lift it up some giaing a small amount of internal space. my friend had a sub that wouldnt fit the box he had we used 3 1" tall rings under the sub to hold it up higher and used some strong glue... its made by elmer called gorilla something it makes a good rock solid seal.
hope this helps
Chronos
Bigeazy4387 on 10/26/2004 13:12:12
aight thanx for tha help tha reason i cant build a bigger box is i have already built the biggest box that can come in and out of the car and it has to be able to now the reason i wanted to flip them is because i get very nice low frequencies 45Hz and down but when i listen to rock with bass tones like pink floyd it tends to slip off and get sloppy i have improved it by setting my ssf around 50hz and my lpf at 100 that made the tones a little cleaner but i still would like more now i came to the conclusion flipping the woofers would be the best bet because of the issue of it having to be able to come in and out with relative ease now is there a way to cover the back of the woofers or anything like that to protect them from dust i have nothing else in my trunk but my stereo so im not worried about magnetic fields
Victor on 10/26/2004 14:07:24
hmmm... i know it would not be nice to advise you what i am going to ..lol.. i know its a very controversial one.. yet..
There is a type of enclosure which is actually not an enclosure...lol... confused??..
ok.. it called the dipole arrangement or open baffle installation..
you would be wondering how it cud produce bass.. well.. these kind of woofer installations have been famous for producing unaltered pure bass frequencies.
its use in car audio is rarest of the rare.. but if u got a good wallet to experiment . it can give u mind boggling results.. its very tricky. .yet if u can really do it, you wud really enjoy listening to hours and hours of pink floyd..
if you are a beginner i would discourage experimenting this..
here's a link if u wanna read more about it..
http://www.diysubwoofers.org/dipole/
I doubt its use in car audio tooo,,,because there are a lot of factors which count when we talk about the behaviour of sound in the interiors of a car and a room...there is a lot of difference between them..
here's another way out..
its called the passive radiator installation..
http://www.diysubwoofers.org/prd/
.........................................................................................................................
If you have finally decided to go with your kind of installation of inverting the woofers then i suggest making a frame with extreme permeable membrane or a net wrapped around it.. and then covering the rear of the woofer... with the netted frame box..
comments...?
Victor
swez on 10/26/2004 15:01:20
Hold the phone here... did you say 2 x 18" Comp VR's? The min/max specs sealed per sub is 2.2 - 5.4ft^3 sealed per sub. Sub displacement is ~400 in^3 per sub. (0.23 cf/sub) So, pulling the sub baskets outside the box will net a 2.4 cf enclosure. NOT A BIG FACTOR HERE. NO REAL BENEFITS !!!
Am confused... is that 2 subs in a 2.2 cf sealed box OR each sub is in a 2.2 cf chamber. (total internal is close to 4.5cf) ?
I do see 1 possible solution here. Use only 1 sub in that size enclosure. A 4.5 cf sealed will give you much better low end bass with less effort and power. A single 18" VR is rated at 1000 RMS, so RMS power handling is not an issue here. I assume nothing... but what amp are you powering these subs with now?
Please, more details as maybe I'm just a bit slow on catching the flow at the moment. GRIN
Swez
Bigeazy4387 on 10/26/2004 16:32:23
the model number on these woofers is c18d8 kicker compvr they are from 1999 they are used in very small sealed boxes as i stated above there range is 2.2 to 3.3 the subs are in seperate sealed chambers of 2.25 cu ft apiece now the problem i am having is 1 sub is completely sealed and it makes noise from the cone the noise is n ot audible in the car only when you pop the trunk and are standing in front of it now the other is not completely sealed and it doesn't make the noise i switched the woofers so its not the woofers it is the box so what i came to is that since the unsealed woofer has a little more air relief that the only problem with the sealed woofer is it has a slightly too small of an enclosure so i was going to flip them to get justn that little amount of space now the amp i use is a power acoustik hyper bass series lt/1440 it is not on their website it puts out 720watts rms at 4ohms bridged the woofers are rated at 500w apice so it is sufficient enough man i know what im doing i was just asking how to flip the things around
LC1 on 10/26/2004 18:17:28
What would be the point of flipping them over to gain just .4 extra cu ft you won't hear a difference? And as for you not liking the bass with pink flyod is because it is an 18" woofer, no where near the optimum size for a good SQ woofer, just pure SPL.
Also if you are hearing a ratleing noise from the sealed box it is because it probably not sealed properly. Use a generous amount of silicone caulking along all the internal joints. Ensuring that your enclosure is 100% sealed will net more of an audiable difference in the sound quality, the inverting your subs.
If you have anymore questions, feel free to asks
Jay
Bigeazy4387 on 10/27/2004 08:55:54
i am completely sure there are no seal leaks i used liquid nails on all the joints. and i know it wont get great sq i sacrificed that when i bought them but i plugged the woofer that has a leak around the woofer ring by itself and it sounded very pleasing but i hooked the 1 up without any leaks and it was just missing a little space so if i got .4 cu .ft of space if im right it would be plenty sufficient if not then all i did is waste a little of my time experimenting
Relax_The_Mind on 10/27/2004 19:46:04
I was about to say that you could invert the subs but looking as they are in the trunk I would say nay.
Mine are inverted but mine are also coverted by a breathable tarp and my entire trunk is nothing but a speaker box and amp. Foreign objects never enter the trunk.
You get a go for the inverting of subs from me if you follow certain precautions. Once again there is no difference in the mechanics of it and the main difference is the gain in airspace and the wiring is outside. In your case there is no real benefit as others stated.
Im not really understandint what your asking but all you have to do to invert subs is simply "invert" them. wiring is the same.
And correction. No those subs may not be getting the power they need. Subs need more power to work optimally when in an enclosure that is smaller than spec. So you would probably need to be pushing close to 800w x2 rms.
i probably made no sense
vicflo
Bigeazy4387 on 10/28/2004 09:02:02
na man you were the most help you told me what i needed but i have a couple of questions what materials are your breathable tarps and do they hurt anything another these subs are rated at 500w apiece that is pushing them really hard and i am giving them 720w plently to take them to xmax seeing as xmax is only 11mm. does the trunk have to be completely sealed off because my trunk also is nothing but a amp and subs
and you made plently of sense thanx for the help
Relax_The_Mind on 10/28/2004 13:42:50
Well the tarp came with my car. it rolls up likt a window shade.
the tarp I used in several cars (mostly hatchbacks) is a fabric that is similar to windows screens except it is fabric not metal. I mostly do it for security reasons. Actually they do sell fabric type screens at hardware stores also. But you can find it at most fabric shops. (along with marine vinyl which is better than regular vinyl for carpeting)
well if your trunk is going to be for nothing but subs/amps I wouldnt see many problems with you doing that setup. You can block off the sub section with the fabric and make it removable so you can either show it off or have it stealthed away. Simple frame with scrap wood furniture nails, fabric tacks and some glue.
To make it look better I would use power wire. like 8awg or something. It will give it that industrial look instead of regular speaker wire which i thinkk doesnt look many enough.
The cool part about it is that you can easily rewire it without physically unscrewing the sub which is when most people damage them (screwdriver poking the cone/surround)
vicflo
Bigeazy4387 on 10/29/2004 09:02:02
well i run 10ga stinger expert so it will look real nice i just wanted to give you 1 more thanx but i also have a question do you put the tarp directly around the sub or if you didnt can u?
swez on 10/29/2004 12:11:41
Am wondering if an isobaric design might help in this application. They are commonly used in sub applications where high power is needed and space is minimal. The advantage is a box that is slightly larger than a single sub would require, but the subs are wired in a push/pull configuration. Am sure there are sonic trade offs with Isobaric designs, but will look around for details that may be helpful.
BTW, I believe you know what you are doing here. You have been here a while and have added some very solid answers to others that needed help. I am not questioning your knowledge at all. Keep up the good work!
Cannot find much info on Isobaric sub enclosures. Did find this for starters though. Compound loading, clamshell or Isobarics (face to face)
http://www.the12volt.com/caraudio/boxes4.asp
http://www.the12volt.com/caraudio/boxes2.asp#top
http://www.caraudiohelp.com/custom_car_audio_boxes/custom_car_audio_boxes.htm
There's more out there... but I have to move on. Good luck!
Swez
Bigeazy4387 on 10/29/2004 13:38:45
thanx alot i considered the isobarik design but i have already split the enclosure and have heard that heat build up on isobarik designs is a problem i like to listen to my system all day long if i want to
swez on 10/30/2004 12:09:12
Not sure about heating issues in Isobaric sub designs. The advantage is you can use 2 subs in the same size enclosure as a single sub. A bit less efficient on power as subs are either stacked one in front of the other (compound loading) or mounted face to face, but reverse polarity on one sub. (Isobaric loading)
'Isobaric loading" is a push/pull design where one sub is mounted outside the box. The other is like a normal cone loading enclosure.
"Compounding loading" is where the subs are stacked on e behind the other.
Another deviation of this design, is to use a dual chamber enclosure with a center divider board. The subs face each other. One is wired out of phase with the other. It can be sealed or ported as well. Similar to Bandpass 4th order designs or even 6th order BP/Isobaric loadings
http://www.the12volt.com/caraudio/boxes4.asp
http://www.the12volt.com/caraudio/boxes6.asp
Ported designs will allow for better cooling of the coils and subs in general.
Swez
thanx alot guys,Steven
Replies (17)
swez on 10/25/2004 12:47:44
Don't do the flip routine... can damage your expensive subs as the magnets pick up everything metallic. Bad for the speaker too. (no protection.
If you have not added any polyfill or acoustical damping materials to date, try that. Your subs will deliver better low-end bass response as the damping material will give you ~10% larger enclosure. (Not physically, but acoustically)
How do the subs sound in the box now?
About your English paper, go to a few install shops like BB & CC and see if they can provide a job description for installers. You may even find this detail off BB/CC websites under employment opportunities. How easy that would be huh?
Swez
Bigeazy4387 on 10/25/2004 13:44:32
i have it with polyfill they sound fine i was just lookin for a little more low end but thanx for tha help
Victor on 10/25/2004 15:11:19
strictly no flipping the woofers..hehehehe.. of-course u can experiment if u want .. but no one around here for a while would recommend it..
if you are running it on an amp with a low pass filter try turning it on.. you may get a small bit of difference.. i fell u must be knowing this but many people forget some minute details. hence thought might just remind u..
why dont u build a new enclosue for ur woofers..??
Victor...
uochronos on 10/25/2004 15:23:04
flipping them over has far more cons then pros. cons would be risk of damageing the motor tructure of the sub from materials geating in. damage from metal being pulled into the magnet or into the motor strocture and trust me stuff well be pulled in especialy in a large speaker like this. also what is the displacment of this speaker? i cant imagine gianing alot of low end by adding that realativly small amount. the only pro i can see is you gain that small amount of space.
another option is to get 1" thick MDF and cut rings out of it. to put under the sub and lift it up some giaing a small amount of internal space. my friend had a sub that wouldnt fit the box he had we used 3 1" tall rings under the sub to hold it up higher and used some strong glue... its made by elmer called gorilla something it makes a good rock solid seal.
hope this helps
Chronos
Bigeazy4387 on 10/26/2004 13:12:12
aight thanx for tha help tha reason i cant build a bigger box is i have already built the biggest box that can come in and out of the car and it has to be able to now the reason i wanted to flip them is because i get very nice low frequencies 45Hz and down but when i listen to rock with bass tones like pink floyd it tends to slip off and get sloppy i have improved it by setting my ssf around 50hz and my lpf at 100 that made the tones a little cleaner but i still would like more now i came to the conclusion flipping the woofers would be the best bet because of the issue of it having to be able to come in and out with relative ease now is there a way to cover the back of the woofers or anything like that to protect them from dust i have nothing else in my trunk but my stereo so im not worried about magnetic fields
Victor on 10/26/2004 14:07:24
hmmm... i know it would not be nice to advise you what i am going to ..lol.. i know its a very controversial one.. yet..
There is a type of enclosure which is actually not an enclosure...lol... confused??..
ok.. it called the dipole arrangement or open baffle installation..
you would be wondering how it cud produce bass.. well.. these kind of woofer installations have been famous for producing unaltered pure bass frequencies.
its use in car audio is rarest of the rare.. but if u got a good wallet to experiment . it can give u mind boggling results.. its very tricky. .yet if u can really do it, you wud really enjoy listening to hours and hours of pink floyd..
if you are a beginner i would discourage experimenting this..
here's a link if u wanna read more about it..
http://www.diysubwoofers.org/dipole/
I doubt its use in car audio tooo,,,because there are a lot of factors which count when we talk about the behaviour of sound in the interiors of a car and a room...there is a lot of difference between them..
here's another way out..
its called the passive radiator installation..
http://www.diysubwoofers.org/prd/
.........................................................................................................................
If you have finally decided to go with your kind of installation of inverting the woofers then i suggest making a frame with extreme permeable membrane or a net wrapped around it.. and then covering the rear of the woofer... with the netted frame box..
comments...?
Victor
swez on 10/26/2004 15:01:20
Hold the phone here... did you say 2 x 18" Comp VR's? The min/max specs sealed per sub is 2.2 - 5.4ft^3 sealed per sub. Sub displacement is ~400 in^3 per sub. (0.23 cf/sub) So, pulling the sub baskets outside the box will net a 2.4 cf enclosure. NOT A BIG FACTOR HERE. NO REAL BENEFITS !!!
Am confused... is that 2 subs in a 2.2 cf sealed box OR each sub is in a 2.2 cf chamber. (total internal is close to 4.5cf) ?
I do see 1 possible solution here. Use only 1 sub in that size enclosure. A 4.5 cf sealed will give you much better low end bass with less effort and power. A single 18" VR is rated at 1000 RMS, so RMS power handling is not an issue here. I assume nothing... but what amp are you powering these subs with now?
Please, more details as maybe I'm just a bit slow on catching the flow at the moment. GRIN
Swez
Bigeazy4387 on 10/26/2004 16:32:23
the model number on these woofers is c18d8 kicker compvr they are from 1999 they are used in very small sealed boxes as i stated above there range is 2.2 to 3.3 the subs are in seperate sealed chambers of 2.25 cu ft apiece now the problem i am having is 1 sub is completely sealed and it makes noise from the cone the noise is n ot audible in the car only when you pop the trunk and are standing in front of it now the other is not completely sealed and it doesn't make the noise i switched the woofers so its not the woofers it is the box so what i came to is that since the unsealed woofer has a little more air relief that the only problem with the sealed woofer is it has a slightly too small of an enclosure so i was going to flip them to get justn that little amount of space now the amp i use is a power acoustik hyper bass series lt/1440 it is not on their website it puts out 720watts rms at 4ohms bridged the woofers are rated at 500w apice so it is sufficient enough man i know what im doing i was just asking how to flip the things around
LC1 on 10/26/2004 18:17:28
What would be the point of flipping them over to gain just .4 extra cu ft you won't hear a difference? And as for you not liking the bass with pink flyod is because it is an 18" woofer, no where near the optimum size for a good SQ woofer, just pure SPL.
Also if you are hearing a ratleing noise from the sealed box it is because it probably not sealed properly. Use a generous amount of silicone caulking along all the internal joints. Ensuring that your enclosure is 100% sealed will net more of an audiable difference in the sound quality, the inverting your subs.
If you have anymore questions, feel free to asks
Jay
Bigeazy4387 on 10/27/2004 08:55:54
i am completely sure there are no seal leaks i used liquid nails on all the joints. and i know it wont get great sq i sacrificed that when i bought them but i plugged the woofer that has a leak around the woofer ring by itself and it sounded very pleasing but i hooked the 1 up without any leaks and it was just missing a little space so if i got .4 cu .ft of space if im right it would be plenty sufficient if not then all i did is waste a little of my time experimenting
Relax_The_Mind on 10/27/2004 19:46:04
I was about to say that you could invert the subs but looking as they are in the trunk I would say nay.
Mine are inverted but mine are also coverted by a breathable tarp and my entire trunk is nothing but a speaker box and amp. Foreign objects never enter the trunk.
You get a go for the inverting of subs from me if you follow certain precautions. Once again there is no difference in the mechanics of it and the main difference is the gain in airspace and the wiring is outside. In your case there is no real benefit as others stated.
Im not really understandint what your asking but all you have to do to invert subs is simply "invert" them. wiring is the same.
And correction. No those subs may not be getting the power they need. Subs need more power to work optimally when in an enclosure that is smaller than spec. So you would probably need to be pushing close to 800w x2 rms.
i probably made no sense
vicflo
Bigeazy4387 on 10/28/2004 09:02:02
na man you were the most help you told me what i needed but i have a couple of questions what materials are your breathable tarps and do they hurt anything another these subs are rated at 500w apiece that is pushing them really hard and i am giving them 720w plently to take them to xmax seeing as xmax is only 11mm. does the trunk have to be completely sealed off because my trunk also is nothing but a amp and subs
and you made plently of sense thanx for the help
Relax_The_Mind on 10/28/2004 13:42:50
Well the tarp came with my car. it rolls up likt a window shade.
the tarp I used in several cars (mostly hatchbacks) is a fabric that is similar to windows screens except it is fabric not metal. I mostly do it for security reasons. Actually they do sell fabric type screens at hardware stores also. But you can find it at most fabric shops. (along with marine vinyl which is better than regular vinyl for carpeting)
well if your trunk is going to be for nothing but subs/amps I wouldnt see many problems with you doing that setup. You can block off the sub section with the fabric and make it removable so you can either show it off or have it stealthed away. Simple frame with scrap wood furniture nails, fabric tacks and some glue.
To make it look better I would use power wire. like 8awg or something. It will give it that industrial look instead of regular speaker wire which i thinkk doesnt look many enough.
The cool part about it is that you can easily rewire it without physically unscrewing the sub which is when most people damage them (screwdriver poking the cone/surround)
vicflo
Bigeazy4387 on 10/29/2004 09:02:02
well i run 10ga stinger expert so it will look real nice i just wanted to give you 1 more thanx but i also have a question do you put the tarp directly around the sub or if you didnt can u?
swez on 10/29/2004 12:11:41
Am wondering if an isobaric design might help in this application. They are commonly used in sub applications where high power is needed and space is minimal. The advantage is a box that is slightly larger than a single sub would require, but the subs are wired in a push/pull configuration. Am sure there are sonic trade offs with Isobaric designs, but will look around for details that may be helpful.
BTW, I believe you know what you are doing here. You have been here a while and have added some very solid answers to others that needed help. I am not questioning your knowledge at all. Keep up the good work!
Cannot find much info on Isobaric sub enclosures. Did find this for starters though. Compound loading, clamshell or Isobarics (face to face)
http://www.the12volt.com/caraudio/boxes4.asp
http://www.the12volt.com/caraudio/boxes2.asp#top
http://www.caraudiohelp.com/custom_car_audio_boxes/custom_car_audio_boxes.htm
There's more out there... but I have to move on. Good luck!
Swez
Bigeazy4387 on 10/29/2004 13:38:45
thanx alot i considered the isobarik design but i have already split the enclosure and have heard that heat build up on isobarik designs is a problem i like to listen to my system all day long if i want to
swez on 10/30/2004 12:09:12
Not sure about heating issues in Isobaric sub designs. The advantage is you can use 2 subs in the same size enclosure as a single sub. A bit less efficient on power as subs are either stacked one in front of the other (compound loading) or mounted face to face, but reverse polarity on one sub. (Isobaric loading)
'Isobaric loading" is a push/pull design where one sub is mounted outside the box. The other is like a normal cone loading enclosure.
"Compounding loading" is where the subs are stacked on e behind the other.
Another deviation of this design, is to use a dual chamber enclosure with a center divider board. The subs face each other. One is wired out of phase with the other. It can be sealed or ported as well. Similar to Bandpass 4th order designs or even 6th order BP/Isobaric loadings
http://www.the12volt.com/caraudio/boxes4.asp
http://www.the12volt.com/caraudio/boxes6.asp
Ported designs will allow for better cooling of the coils and subs in general.
Swez
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