Hello to all,
First post but long time reader, and let me say that this is an awesome forum.
Second I apologize for the poor quality of my cell phone pictures, as well as my poor english which is not my native language.
So, this is about a car subwoofer, specifically, the Porsche Boxster Bose box. The Boxster is a mid rear engine, 2 seats cabriolet, with no room for a decent subwoofer box. Porsche proposed as an option a Bose speaker system, with an enclosure that sits on the shelf on top of the engine, just behind the seats. When the top is down, the roof retracts on top of this box. The box is shallow, about 4".
I don't have picture of the box in the car, but here it is standing alone :
When we turn the box over, we can see the two 5.25" woofers :
When in the car, the woofer faces the engine shelf carpet, and thus there's only about 1/2" between the woofer and the carpet :
Inside the box :
Another view of one of the woofers :
I know the basic theory of closed, vented, passband subwoofer enclosures and I understand how they are designed given a speaker's T/S specs.
But here I don't understand how this particular enclosure is working, as the woofers basically face a wall, and I guess only rear waves are heard through the vent. Is this a passband enclosure with a very small front chamber?
Has anyone any clue on how this type of enclosure work?
The box pictured above is a friend's, not mine. I don't have this expensive option in my car, and I'd like to design my own subwoofer enclosure based on a similar design (because there's no room elsewhere in the car), but to do so I need to understand how it works. I guess this subwoofer will probably sounds like crap (the Bose one blurps more than it thumps) but it's a trade-off I'm willing to try.
Last question, would it be worthwhile to change the woofers in my friend's box? I guess he would have to estimate the T/S of the Bose speaker first, don't you think?
Tanks in advanced for your replies.
First post but long time reader, and let me say that this is an awesome forum.
Second I apologize for the poor quality of my cell phone pictures, as well as my poor english which is not my native language.
So, this is about a car subwoofer, specifically, the Porsche Boxster Bose box. The Boxster is a mid rear engine, 2 seats cabriolet, with no room for a decent subwoofer box. Porsche proposed as an option a Bose speaker system, with an enclosure that sits on the shelf on top of the engine, just behind the seats. When the top is down, the roof retracts on top of this box. The box is shallow, about 4".
I don't have picture of the box in the car, but here it is standing alone :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
When we turn the box over, we can see the two 5.25" woofers :
An externally hosted image should be here but it was not working when we last tested it.
When in the car, the woofer faces the engine shelf carpet, and thus there's only about 1/2" between the woofer and the carpet :
An externally hosted image should be here but it was not working when we last tested it.
Inside the box :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Another view of one of the woofers :
An externally hosted image should be here but it was not working when we last tested it.
I know the basic theory of closed, vented, passband subwoofer enclosures and I understand how they are designed given a speaker's T/S specs.
But here I don't understand how this particular enclosure is working, as the woofers basically face a wall, and I guess only rear waves are heard through the vent. Is this a passband enclosure with a very small front chamber?
Has anyone any clue on how this type of enclosure work?
The box pictured above is a friend's, not mine. I don't have this expensive option in my car, and I'd like to design my own subwoofer enclosure based on a similar design (because there's no room elsewhere in the car), but to do so I need to understand how it works. I guess this subwoofer will probably sounds like crap (the Bose one blurps more than it thumps) but it's a trade-off I'm willing to try.
Last question, would it be worthwhile to change the woofers in my friend's box? I guess he would have to estimate the T/S of the Bose speaker first, don't you think?
Tanks in advanced for your replies.
Looks like a standard vented box to me... I'd ignore the 'flare' as I'm sure it does not do much, but you can model the port and flare in hornresp if you'd like.
I'm assuming your car looks something like this?
http://www.renntech.org/forums/index.php?showtopic=27982&pid=148543&st=20&#entry148543 This guy used focal 5" subs.
If you've got 5" of height, I'd build a sealed box, with the front face at 5" tall, with about 4 of these front facing, not down facing. http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-831 You can trim the steel basket top and bottom to save a little height. I know you said 4", but somehow, I'm guessing 5" might be doable?
You'll also need to follow it up with some bass shakers in your seats. (I know, blasphemy) As ear level bass doesn't 'feel' right. With the shakers turned way down, and crossed very low, it'll fool your ear into hearing what you're missing with the top down.
my 2c. I'm sure others will have better suggestions.
I'm assuming your car looks something like this?
http://www.renntech.org/forums/index.php?showtopic=27982&pid=148543&st=20&#entry148543 This guy used focal 5" subs.
If you've got 5" of height, I'd build a sealed box, with the front face at 5" tall, with about 4 of these front facing, not down facing. http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-831 You can trim the steel basket top and bottom to save a little height. I know you said 4", but somehow, I'm guessing 5" might be doable?
You'll also need to follow it up with some bass shakers in your seats. (I know, blasphemy) As ear level bass doesn't 'feel' right. With the shakers turned way down, and crossed very low, it'll fool your ear into hearing what you're missing with the top down.
my 2c. I'm sure others will have better suggestions.
nope, I'm calling that box 6th order bandpass.. series tuned?
there is a port next to each woofer as well, so when the box is put on the carpeted shelf, you get another chamber infront of the woofers, thats vented into the main chamber the woofers are in
http://www.diysubwoofers.org/bnd/6thord4.htm
oh... wait.. the ports go the whole way though the box...
so, its just a standard 6th order...
there is a port next to each woofer as well, so when the box is put on the carpeted shelf, you get another chamber infront of the woofers, thats vented into the main chamber the woofers are in
http://www.diysubwoofers.org/bnd/6thord4.htm
oh... wait.. the ports go the whole way though the box...
so, its just a standard 6th order...
yup, looks like typical schlock
from Bose...
it does look like a 6th order bandpass.
Why not stick to something tried and true? Maybe an Isobaric enclosure as found in the Boogieman sub project ? Basically 36" X 24" X 4" using the previously mentioned Tangbands. Stick with 2 of them and you could get that all into 36" X 12" X 4" , close to the space you have...
or have a look at the LAT line array woofs... .
Those could be very interesting and suitable for very small enclosures...
from Bose...
it does look like a 6th order bandpass.
Why not stick to something tried and true? Maybe an Isobaric enclosure as found in the Boogieman sub project ? Basically 36" X 24" X 4" using the previously mentioned Tangbands. Stick with 2 of them and you could get that all into 36" X 12" X 4" , close to the space you have...
or have a look at the LAT line array woofs... .
Those could be very interesting and suitable for very small enclosures...
I'm not buying the 6th order bandpass. There is nothing to define a chamber, or a port. If anything, it's a standard vented box, with 'acoustic loading.' Measure the bose driver T/S params, and measure the amount of air in front of the driver, add that mass to your measured driver mass to modify your T/S. (search will turn up a great thread on adding mass to a 55-2421) Considering air is 1.2g/liter approx, and you have less than a liter of air in front of the driver, I suspect that the few hz of lower fs, accomplished by the acoustic loading would be inaudible vs if it were not there.
boogieman isobaric??
isobaric is driver to driver arrangement, the boogieman is standard vented enclosure, not isobaric.
The TB have a reasonable xmax, unlike the bose, so up or down facing would be problematic, and prone to driver damage -- forward facing is the only practical arrangement in my opinion.
boogieman isobaric??
isobaric is driver to driver arrangement, the boogieman is standard vented enclosure, not isobaric.
The TB have a reasonable xmax, unlike the bose, so up or down facing would be problematic, and prone to driver damage -- forward facing is the only practical arrangement in my opinion.
I disagree with 6th order bandpass aswell. They are two tuned chambers - one for each side of the driver. Putting the "woofers" to the carpet would give a similar effect to slot loading a driver, which reduces excursion. If the carpet blocks it completely, it's a 4th order bandpass.
TBH, I'd class it as a 4th order bandpass with pass ive radiator. The --unbraced-- plastic cabinet would happily ring along, like a PR.
Joking aside, out of the car, it's a simple, vented box. In the car, it would appear to be either an acoustically damped vented, or 4th order bandpass, dependant on if there's a route for the front of the "woofer" to your ears.
BTW - it's a Porsche Boxster... www.lmgtfy.com/?q=porsche boxster
So space will be at a premium.
Chris
PS - I say woofer with quote marks because there's no way I'd class a speaker that small as a woofer.
TBH, I'd class it as a 4th order bandpass with pass ive radiator. The --unbraced-- plastic cabinet would happily ring along, like a PR.
Joking aside, out of the car, it's a simple, vented box. In the car, it would appear to be either an acoustically damped vented, or 4th order bandpass, dependant on if there's a route for the front of the "woofer" to your ears.
BTW - it's a Porsche Boxster... www.lmgtfy.com/?q=porsche boxster
So space will be at a premium.
Chris
PS - I say woofer with quote marks because there's no way I'd class a speaker that small as a woofer.
DIY subwoofer classes it as a
6th order series tuned system .
Regardless, There's gotta be a better way..simple 5" or 6" cardboard tube and a couple of small woofers such as the Tangbands....I'm sure it'd sound a lot better ...
6th order series tuned system .
Regardless, There's gotta be a better way..simple 5" or 6" cardboard tube and a couple of small woofers such as the Tangbands....I'm sure it'd sound a lot better ...
I agree with the Tangbands idea, but I'm not buying the idea of http://www.diysubwoofers.org/bnd/6thord4.htm , because the port fires forwards, the drivers fire downwards, into a carpet.
Something like http://www.parts-express.com/projectshowcase/indexn.cfm?project=Firebird might be fun to try.
Chris
Something like http://www.parts-express.com/projectshowcase/indexn.cfm?project=Firebird might be fun to try.
Chris
FWIW, when I looked at the photos the other day I saw a rather innovatively laid out, high tuned (small front chamber) 6th order BP once secured/sealed to a surface with a pair of high Fs 'full-range' drivers to presumably add some surround ambiance and after taking a 'fresh' look just now I still believe it is. IOW, other than the layout, just another typical B@$3 alignment.
GM
GM
GM, I agree, it's typical B........ no highs no lows, gotta be ......
As for Chris' firebird http://www.parts-express.com/projec...roject=Firebird suggestion, that was EXACTLY what I had in mind, only using the 5 1/4" TB drivers, due to the limited height requirement.
As for Chris' firebird http://www.parts-express.com/projec...roject=Firebird suggestion, that was EXACTLY what I had in mind, only using the 5 1/4" TB drivers, due to the limited height requirement.
So Arno, what is your budget? Can the enclosure be any taller and still allow the top to be low enough when down? Are you a handy enough woodworker to make something shaped like the Bose unit so as to maximize the limited space you have available? While you still have it in your custody you may wanna trace its outline to a piece of cardboard, would save you some time if you do make your own unit eventually.
Just because Bose has made some new ultra high-tech 11th order NASA level enclosure y'all don't understand don't mean its time to break out the Bose HaterAde, maybe they are onto something here. I suppose it should sound good if there is any validity to my statement though.
How much was the Bose SubWoofer option new from Porsche? I wonder what they are goin for on eBay.
Just because Bose has made some new ultra high-tech 11th order NASA level enclosure y'all don't understand don't mean its time to break out the Bose HaterAde, maybe they are onto something here. I suppose it should sound good if there is any validity to my statement though.
How much was the Bose SubWoofer option new from Porsche? I wonder what they are goin for on eBay.
jbell said:
OK, so are you saying you now agree that it's probably a 6th order alignment or just that whatever it is a typically performing B@$3 product?
Regardless, for a convertible/roadster, a 6th order alignment makes sense to me with 4th order, sealed, TL or TQWT a better choice overall for a typical closed in vehicle.
GM
901Fixer said:
Yep........ The few on-line reviews I've read were mostly very negative plus the number of used units available.......... Nothing wrong with any of their system concepts IMO, just their implementation and especially their marketing strategy (my reason for trashing them every appropriate chance I get).
Dunno, I couldn't find it on-line, so was going to scope it out at the local dealer a few miles away. Didn't check fleabay, but 'make offer' ruled otherwise.
GM
ultimately
who cares?
the DIYsubwoofer picture is effectively the same thing as this Bose whatever you call it....
I think all can agree that almost anything else would be better implemented, and there are 4" dedicated woofers (not subs ) available at a very reasonable cost, that can provide enjoyable bass. Rear fill in a car of this type is a waste anyways...but bass isn't.
Just remember that whatever gets built (if that is the final goal for Arno), it will have completely different sounds when under the top or open air driving...
who cares?
the DIYsubwoofer picture is effectively the same thing as this Bose whatever you call it....
I think all can agree that almost anything else would be better implemented, and there are 4" dedicated woofers (not subs
) available at a very reasonable cost, that can provide enjoyable bass. Rear fill in a car of this type is a waste anyways...but bass isn't. Just remember that whatever gets built (if that is the final goal for Arno), it will have completely different sounds when under the top or open air driving...
Sorry for my late reply, I've been swamped at work lately. Thanks to all for your replies and ideas, I really appreciate.
Two things that could be important. In the Bose box, the holes next to the woofers (red arrow) are not vents, there are sealed and are there for locking the box onto the shelf.
If the front chamber is actually vented, it is then through the 3" grills in front of the box (yellow arrow) but then the waves would have to travel through a very narrow channel (at the right of the yellow arrow) :
I'm pretty sure it will be difficult to fit 5"1/2 speakers in there. I'd have to actually measure the space between the self and the roof when it's down, but I'm confident there's less than 5".
So what are my options ?
1 - Get a Bose box from eBay for 200 € (Porsche sells it but the price is just silly) and find better (if possible) woofers to replace the Bose ones. This probably means finding the T/S specs of the Bose woofers, but then I'd also have to find the equipment to measure them.
2 - Make my own enclosure based on this Bose design. That was my first idea, because it allows for larger speakers than what the available height allows. But after reading your answers, it just seems too complicated for me to design.
3 - Make my own enclosure based on something else than the Bose box. I have to read more on the different ideas you already mentioned. I'll have to check if I can source the TB drivers in Europe.
4 - ???
I'm fairly good at woodworking and I've got tools, so building an enclosure, even a complicated one, is not a problem. However I realize that my knowledge is actually limited, I could design a vented box given T/S parameters, but more complicated enclosures are a challenge. I have to study more (any good pointers BTW?).
As far as budget, I'd like to keep it under 500 €, else it won't pass the wife acceptance factor (this car is a money sink to her ;-). At least at first, I plan to use spare channels from my Audison amp that is already in the front trunk.
Again, I really appreciate the help.
Two things that could be important. In the Bose box, the holes next to the woofers (red arrow) are not vents, there are sealed and are there for locking the box onto the shelf.
If the front chamber is actually vented, it is then through the 3" grills in front of the box (yellow arrow) but then the waves would have to travel through a very narrow channel (at the right of the yellow arrow) :
An externally hosted image should be here but it was not working when we last tested it.
I'm pretty sure it will be difficult to fit 5"1/2 speakers in there. I'd have to actually measure the space between the self and the roof when it's down, but I'm confident there's less than 5".
So what are my options ?
1 - Get a Bose box from eBay for 200 € (Porsche sells it but the price is just silly) and find better (if possible) woofers to replace the Bose ones. This probably means finding the T/S specs of the Bose woofers, but then I'd also have to find the equipment to measure them.
2 - Make my own enclosure based on this Bose design. That was my first idea, because it allows for larger speakers than what the available height allows. But after reading your answers, it just seems too complicated for me to design.
3 - Make my own enclosure based on something else than the Bose box. I have to read more on the different ideas you already mentioned. I'll have to check if I can source the TB drivers in Europe.
4 - ???
I'm fairly good at woodworking and I've got tools, so building an enclosure, even a complicated one, is not a problem. However I realize that my knowledge is actually limited, I could design a vented box given T/S parameters, but more complicated enclosures are a challenge. I have to study more (any good pointers BTW?).
As far as budget, I'd like to keep it under 500 €, else it won't pass the wife acceptance factor (this car is a money sink to her ;-). At least at first, I plan to use spare channels from my Audison amp that is already in the front trunk.
Again, I really appreciate the help.
Arno said:
Ok, that is pretty funny and probaly the source of most of the confusion here. They look more like ports/vents than any other item on the enclosure.
Since you can build something that is what I would do. Don't worry about designing it, just build whatever you like gets suggested here.
What brand of drivers are easily available to you? TangBand is great and very cost effective and all over eBay, sometimes shipped directly from China very reasonably. They definately aren't your only option though.
What will you be powering them with?
Arno said:
Arno said:
Arno,
1. I dont hink the 3" vent is for the bass. The 3" vent might well be for the 2.5" 'wide-range' also included as part of this system.
2. I suspect this is a variation of Bose 'wave-guide' system as used by their 'wave-guide' radio
http://autospeed.com/cms/title_The-Bose-Wave-Radio/A_1372/article.html
3. Do not be constrained by the shallowness of the box. Dan Wiggins and ADI were able to design a 10" woofer that might be useable (thought the Qts seems a bit low for IB).
http://stereointegrity.com/forums/2645-post7.html
http://www.acousticdev.com/cms/inde...t-sub-woofer&catid=38:uncategorized&Itemid=60
Your best bet would be to fabricate a fiberglass box that is maybe a bit deeper and hence has more volume for maybe 2 6-8" woofers. Used in conjection with the W3-871, CHR70, FF85K or other such 3" wide range you should be able to produce better sound than Bose. Enjoy.
Just do not expect this system to do Trance, House, or Hip-Hop at loud volumes. For Jazz, Rock, Blues, etc.. it will do fine.
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