#1 what are the pros and cons to "down firing" subs into the box rather than mounting them traditionally
# I have a pair of road thunder mtx 12's and they dont seem to throw nearly as much as my older ones, does that mean then can be pumped harder?
Replies (18)
baine on 08/6/2003 21:09:10
I cant answer your first ? But I would too like to know.
Your 2nd question I do not think there is nuff info there . We need to know the subs model # and type of enclosure its in and rms and peak type of amp. With a guess I will say do not push them over there peak handeling. Some subs with some enclosures can take more than peak but, you need to think why is that the peak power of the sub.... It prob failed or blew at higher power rating .... again that is my input I may be totaly off bace so waite for the GOLDS ta get to ya
Swez on 08/6/2003 22:00:56
Down firing subs are fine for HT applications, but there needs to be enough air space between the woofer cone and the flooring to allow the bass to propogate well. Am sure there are guidelines for this application, but I have not done one. Just know that the more SPL you push through th sub(s) , the more air space is needed to balance pressure waves from the DF subs.
The 2nd question has more to do with efficiency and enclosure airspace than any other aspects... assuming power input is the same to each sub design.
Sealed enclosures have lower SPL output, but more balanced. Ported enclosure can make a modest sub come to life in a big way at certain frrequencies, but power handling will drop as port tuning frequency is met or exceeded.
Does that help?
Swez
baine on 08/6/2003 22:31:20
see told ya i dont know anything
ttocs on 08/7/2003 01:39:59
We do alot of downfiring boxes in this area. The two shops I work at did them alot as their customers wanted to hear the speakers, not see them.
I think that downfiring boxes sound great. The bass seems smoother and cleaner. You don't get any of the mechanical noise from the speaker.
baine on 08/7/2003 06:01:57
Is there a web page that can give me some ideas on how to set up a downfiring box? and mabey explain the +- too it
Tray on 08/7/2003 09:16:45
Greg,
#1 Are you referring to 'flipping' your subs so that the magnet and spider structure are outside of the box, while the cone faces into it?
#2 By 'throw', what are you referring to? The linear excursion of the sub itself? The SPL produced by the setup? The low frequency reproduction?
Baine,
What are you looking to build a downfiring box for? I've built a few in the past, so may be able to help you come up with a design you may like. The only true negatives I've experienced are that it takes longer to plan/design, and it results in lower SPL.
accusedmonk on 08/7/2003 10:22:22
To help the SPL of a downfiring box, which a lot of home stereos/theatres use, try angling the boxes to the sides or back so the sound bouncs back at you, and not straight into the floor of the car. I have no idea if you could, just depends on the space and size of the box(s).
I haven't had any experience with most of this stuff but I just figured you could try it. You might be able to buy just the box for a home theatre sub, or buy it with the sub and take that one out and put the car sub in there. Matching the depths would be the only prob.
Swez on 08/7/2003 14:14:49
No... that's right on target info. Large theater or Pro subs are scooped or arrayed to throw sound out at wide angles either vertically or horizontally. (or both)
Not sure what angle is optimal... but any angle is better than the sub firing against a hard surface and right back into the cone. We know that too little air space for popagation of a bass wave is going to cut SPL and increase mechanical/audible distortions right? Just pure physics and wave propagation equations. (Whatever they may be)
I'm not that smart to run the numbers, but boy, we need a good engineer on this site for stuff like this. Otherwise, there is always the imperical testing method.... What's too much, what's not enough and split the difference til it sounds good. Hey... wadda ya want from a " Dyed in the Wool Salesman" anyway???
Swez
baine on 08/7/2003 17:25:19
Trey It is for a 98 pontiac gran prix , It is in the shop for hail damage :-( so I cant measure the trunk , but I love the look of a downfireing box . I would also love to make a amp rack for my amps , right now they are screwed on to a peice of 3/4 mdf and then hung in the trunk , but you can see all of the wires with the box out and it looks bad. I should have put more time into it but I just wanted my new stuff in ..... Now I am mad at myself for not taking time to do it better . I am the only one that ever sees it as the subs block the view .. but I know thats enuff . I get the car back tomorrow and I will measure it when it gets here... thanks for your help.
Relax_The_Mind on 08/7/2003 17:04:32
Angles...Airspace...Flipped...Downfiring
You have to remember what bass is. A sound... Created by what? Moving air. I think he meant inverting the subs in a box as to show the magnet outside the box. The speaker doesnt make the sound. the box does. If you play your standard sub outside of a box you dont really hear anything at all. To better understand boxes is to look at why we use MDF instead of solid steel or anything else, is because its physical properties resonate around the frequency to hear what we call "Bass". So as long as you make a box that a speaker is designed for, and give the driver enough sitting airspace to give it free movement. Placement and direction would not matter as much. Although the general rule is to have the sound waves pointed to your ears in some way, which is why sedans do so well with the subs facing the rear making the sound waves reflect to the front.
I dont see any real cons to inverting subs but i do see improvements in some cases like it can increase your box by maybe .13 depending on the displacement of the woofer. Oh and rewiring is much easier than removing several screws.
Back in the day it wasnt really common to invert subs as it looked funny. But now with all the chrome and plated metals and designs it just looks better to have a sub or two inverted. If you ever been to competitions or ahve seen pictures. Many of the vehicles invert the subs for looks and to save box space.
RTM
ps. Do i ever make sense or do i type in fragments? hehe
baine on 08/7/2003 19:44:51
Trey I Just love the look of the downfiring box ( I do not know how it sounds but I am putting it in a trunk so I do not know if that would be ok to do it that way. If you have ideas or even a reg box Idea I am game to try it . Would love to brainstorm with ya , but rember I am new to the tec part of this so .. bear with me plz. Ok the Measurements of my trunk are Opening: 44 1/2 inches across and 20 1/2 inches wide In the trunk are 37in. across the narrowest part 18in. hight and 37 deep (do not want to use all the depth. My current BP box measures H14w18L32 1/2. I also have the speaker specs if it helps
Legacy LFW12X
Power (peak) 500Watts
Nom.Impedance 4
Voice coil 1.5
Magnet Structure 80
Fs(Hz) 45.4
Qms 1.55
Qes 0.87
Qts0.56
SPL9dB 89.0
Vas (cu. ft) 1.745
I have two of them like that. Dose that help ya ? I want some other subs and I should find out tomorrow if the wife will let me get some diffrent subs . I just need to find out if the bank is going to take all of the money for the hail damage repair. got 3300 and only cost 1600 so the bank gave us 1600+ 700 incase the repair cost was more and took the rest to put on the loan . If they do not want the 700 Hehe I am getting some subs ( I hope I have a wife who thinks my subs are good nuff :-( )
greg311 on 08/7/2003 21:32:30
so, do you lose spl when you mount the subs inverted? I have my subs mounted the normal way with the box facing the hatch back and they sound good but they would look so cool inverted but a problem is with them inverted the box wouldnt be able to stand up facing the hatchback I would have to lay it down but most importantly I am concerned with sq and loudness then looks
Swez on 08/8/2003 08:00:07
Many have played with inverted sub ideas and they will work, but the problem I see is exposed cone/basket to an unprotected environment. If in a trunk/or hatchback with other stuff floating around back there, could damage the sub right?
Also, the balance of the box gets screwy if one uses a large sub with heavy magnets. Would have to anchor the enclosure to the floor or strap in in somehow to prevent it from flipping over.
Basically, an inverted sub acts similar to a BP in some respects. The front of the sub fires into the box while the rear enclosure is more like a free air deal. Besides, the sub was not designed for this application either. But can try it if you wish... some really hear a difference, others do not.
Swez
Tray on 08/8/2003 09:15:40
One thing to keep in mind, is that all of your backpressure is gone, so power handling is reduced. Not a huge loss, but if you are going to try this, please do so responsibly, as I'd hate to see blown subs from an oversight such as this.
baine on 08/8/2003 10:05:15
Yes I realize that the subs will not be able to handel power that they norm would
compvr15s on 08/8/2003 14:32:58
i heard a 12 inch kicker L7 inverted in a ported box in a ford probe hatchback, i dont think it was just me but it really seemed like it was louder that way, could that be because of the ported box plus the hatchback being pretty close the the back of the sub. i had the same exact box when i had my L7's but i never did this because i was scared that it would blow the speaker, which i guess didnt really matter cuz i blew about 8 of them lol. CompVRs all the way baby!! lol
ttocs on 08/8/2003 22:13:40
you don't have to reduce the power when you invert the sub. As long as there is an inclosure infront or in back it will act the same.
Swez on 08/9/2003 09:54:07
As ttocs mentioned, there will be pressure on the front side of the cone, into the box... just not in the traditional way most subs are made.
There was a home system design that used this idea by Ohm (E series?) speakers a few years back. It worked well in their design as the radiation pattern off the rear of the cone is slightly different than off the front side of the cone. They actually were considered "State Of The Art" back when they first came out too.
Give it a try and see if you like the results. Some do, other do not.
Swez
# I have a pair of road thunder mtx 12's and they dont seem to throw nearly as much as my older ones, does that mean then can be pumped harder?
Replies (18)
baine on 08/6/2003 21:09:10
I cant answer your first ? But I would too like to know.
Your 2nd question I do not think there is nuff info there . We need to know the subs model # and type of enclosure its in and rms and peak type of amp. With a guess I will say do not push them over there peak handeling. Some subs with some enclosures can take more than peak but, you need to think why is that the peak power of the sub.... It prob failed or blew at higher power rating .... again that is my input I may be totaly off bace so waite for the GOLDS ta get to ya
Swez on 08/6/2003 22:00:56
Down firing subs are fine for HT applications, but there needs to be enough air space between the woofer cone and the flooring to allow the bass to propogate well. Am sure there are guidelines for this application, but I have not done one. Just know that the more SPL you push through th sub(s) , the more air space is needed to balance pressure waves from the DF subs.
The 2nd question has more to do with efficiency and enclosure airspace than any other aspects... assuming power input is the same to each sub design.
Sealed enclosures have lower SPL output, but more balanced. Ported enclosure can make a modest sub come to life in a big way at certain frrequencies, but power handling will drop as port tuning frequency is met or exceeded.
Does that help?
Swez
baine on 08/6/2003 22:31:20
see told ya i dont know anything
ttocs on 08/7/2003 01:39:59
We do alot of downfiring boxes in this area. The two shops I work at did them alot as their customers wanted to hear the speakers, not see them.
I think that downfiring boxes sound great. The bass seems smoother and cleaner. You don't get any of the mechanical noise from the speaker.
baine on 08/7/2003 06:01:57
Is there a web page that can give me some ideas on how to set up a downfiring box? and mabey explain the +- too it
Tray on 08/7/2003 09:16:45
Greg,
#1 Are you referring to 'flipping' your subs so that the magnet and spider structure are outside of the box, while the cone faces into it?
#2 By 'throw', what are you referring to? The linear excursion of the sub itself? The SPL produced by the setup? The low frequency reproduction?
Baine,
What are you looking to build a downfiring box for? I've built a few in the past, so may be able to help you come up with a design you may like. The only true negatives I've experienced are that it takes longer to plan/design, and it results in lower SPL.
accusedmonk on 08/7/2003 10:22:22
To help the SPL of a downfiring box, which a lot of home stereos/theatres use, try angling the boxes to the sides or back so the sound bouncs back at you, and not straight into the floor of the car. I have no idea if you could, just depends on the space and size of the box(s).
I haven't had any experience with most of this stuff but I just figured you could try it. You might be able to buy just the box for a home theatre sub, or buy it with the sub and take that one out and put the car sub in there. Matching the depths would be the only prob.
Swez on 08/7/2003 14:14:49
No... that's right on target info. Large theater or Pro subs are scooped or arrayed to throw sound out at wide angles either vertically or horizontally. (or both)
Not sure what angle is optimal... but any angle is better than the sub firing against a hard surface and right back into the cone. We know that too little air space for popagation of a bass wave is going to cut SPL and increase mechanical/audible distortions right? Just pure physics and wave propagation equations. (Whatever they may be)
I'm not that smart to run the numbers, but boy, we need a good engineer on this site for stuff like this. Otherwise, there is always the imperical testing method.... What's too much, what's not enough and split the difference til it sounds good. Hey... wadda ya want from a " Dyed in the Wool Salesman" anyway???
Swez
baine on 08/7/2003 17:25:19
Trey It is for a 98 pontiac gran prix , It is in the shop for hail damage :-( so I cant measure the trunk , but I love the look of a downfireing box . I would also love to make a amp rack for my amps , right now they are screwed on to a peice of 3/4 mdf and then hung in the trunk , but you can see all of the wires with the box out and it looks bad. I should have put more time into it but I just wanted my new stuff in ..... Now I am mad at myself for not taking time to do it better . I am the only one that ever sees it as the subs block the view .. but I know thats enuff . I get the car back tomorrow and I will measure it when it gets here... thanks for your help.
Relax_The_Mind on 08/7/2003 17:04:32
Angles...Airspace...Flipped...Downfiring
You have to remember what bass is. A sound... Created by what? Moving air. I think he meant inverting the subs in a box as to show the magnet outside the box. The speaker doesnt make the sound. the box does. If you play your standard sub outside of a box you dont really hear anything at all. To better understand boxes is to look at why we use MDF instead of solid steel or anything else, is because its physical properties resonate around the frequency to hear what we call "Bass". So as long as you make a box that a speaker is designed for, and give the driver enough sitting airspace to give it free movement. Placement and direction would not matter as much. Although the general rule is to have the sound waves pointed to your ears in some way, which is why sedans do so well with the subs facing the rear making the sound waves reflect to the front.
I dont see any real cons to inverting subs but i do see improvements in some cases like it can increase your box by maybe .13 depending on the displacement of the woofer. Oh and rewiring is much easier than removing several screws.
Back in the day it wasnt really common to invert subs as it looked funny. But now with all the chrome and plated metals and designs it just looks better to have a sub or two inverted. If you ever been to competitions or ahve seen pictures. Many of the vehicles invert the subs for looks and to save box space.
RTM
ps. Do i ever make sense or do i type in fragments? hehe
baine on 08/7/2003 19:44:51
Trey I Just love the look of the downfiring box ( I do not know how it sounds but I am putting it in a trunk so I do not know if that would be ok to do it that way. If you have ideas or even a reg box Idea I am game to try it . Would love to brainstorm with ya , but rember I am new to the tec part of this so .. bear with me plz. Ok the Measurements of my trunk are Opening: 44 1/2 inches across and 20 1/2 inches wide In the trunk are 37in. across the narrowest part 18in. hight and 37 deep (do not want to use all the depth. My current BP box measures H14w18L32 1/2. I also have the speaker specs if it helps
Legacy LFW12X
Power (peak) 500Watts
Nom.Impedance 4
Voice coil 1.5
Magnet Structure 80
Fs(Hz) 45.4
Qms 1.55
Qes 0.87
Qts0.56
SPL9dB 89.0
Vas (cu. ft) 1.745
I have two of them like that. Dose that help ya ? I want some other subs and I should find out tomorrow if the wife will let me get some diffrent subs . I just need to find out if the bank is going to take all of the money for the hail damage repair. got 3300 and only cost 1600 so the bank gave us 1600+ 700 incase the repair cost was more and took the rest to put on the loan . If they do not want the 700 Hehe I am getting some subs ( I hope I have a wife who thinks my subs are good nuff :-( )
greg311 on 08/7/2003 21:32:30
so, do you lose spl when you mount the subs inverted? I have my subs mounted the normal way with the box facing the hatch back and they sound good but they would look so cool inverted but a problem is with them inverted the box wouldnt be able to stand up facing the hatchback I would have to lay it down but most importantly I am concerned with sq and loudness then looks
Swez on 08/8/2003 08:00:07
Many have played with inverted sub ideas and they will work, but the problem I see is exposed cone/basket to an unprotected environment. If in a trunk/or hatchback with other stuff floating around back there, could damage the sub right?
Also, the balance of the box gets screwy if one uses a large sub with heavy magnets. Would have to anchor the enclosure to the floor or strap in in somehow to prevent it from flipping over.
Basically, an inverted sub acts similar to a BP in some respects. The front of the sub fires into the box while the rear enclosure is more like a free air deal. Besides, the sub was not designed for this application either. But can try it if you wish... some really hear a difference, others do not.
Swez
Tray on 08/8/2003 09:15:40
One thing to keep in mind, is that all of your backpressure is gone, so power handling is reduced. Not a huge loss, but if you are going to try this, please do so responsibly, as I'd hate to see blown subs from an oversight such as this.
baine on 08/8/2003 10:05:15
Yes I realize that the subs will not be able to handel power that they norm would
compvr15s on 08/8/2003 14:32:58
i heard a 12 inch kicker L7 inverted in a ported box in a ford probe hatchback, i dont think it was just me but it really seemed like it was louder that way, could that be because of the ported box plus the hatchback being pretty close the the back of the sub. i had the same exact box when i had my L7's but i never did this because i was scared that it would blow the speaker, which i guess didnt really matter cuz i blew about 8 of them lol. CompVRs all the way baby!! lol
ttocs on 08/8/2003 22:13:40
you don't have to reduce the power when you invert the sub. As long as there is an inclosure infront or in back it will act the same.
Swez on 08/9/2003 09:54:07
As ttocs mentioned, there will be pressure on the front side of the cone, into the box... just not in the traditional way most subs are made.
There was a home system design that used this idea by Ohm (E series?) speakers a few years back. It worked well in their design as the radiation pattern off the rear of the cone is slightly different than off the front side of the cone. They actually were considered "State Of The Art" back when they first came out too.
Give it a try and see if you like the results. Some do, other do not.
Swez
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