No offense
Hi,
@ashok
I understood Your post not as an offense, nor was mine intended as such. Most of the dipole opponents just look at the efficiency of a single- or dual driver dipole, not taking into account, the afore mentioned differences in volume and fs.
Everybody knows that designing speakers is a matter of compromises. You gain certain sonic advantages by loosing on other parameters. With a dipole bass You´re loosing on simplicity. With this I mean, that it is easier and cheaper to build a box and cut one or two holes in it than to build a special structure for 4 drivers.
I know Axel and his partners for some years now and worked with them and can say that roundabout a dipole with 4 drivers (serial-parallel-connected) behaves similarly as a single driver CB or BR with regard to volume and SPL.
Still the dipole will exhibit deeper bass than a CB and much less group delay than BR and less excitation of room modes, i.e it has more degrees of freedom in setting up the system.
jauu
Calvin
ps:
"I've used the ripole concept but with W manifolds and a U-baffle extension on the back" Even though it might look very similar, this doesn´t apply for, since the idea and concept of the ripoles is extreme compactness together with a distinct reduction of the drivers free air resonance. The W-baffle ala Linkwitz claims a reduction of odd harmonics, by having the drivers connected out of phase electrically. But in difference to the BMC-ripole where both drivers work in symmetry, the W-style drivers work under different conditions (3 different chambers -hence no symmetry) thereby swapping any advantage its different driver connection could exhibit with regard to distortion (imo).
Hi,
@ashok
I understood Your post not as an offense, nor was mine intended as such. Most of the dipole opponents just look at the efficiency of a single- or dual driver dipole, not taking into account, the afore mentioned differences in volume and fs.
Everybody knows that designing speakers is a matter of compromises. You gain certain sonic advantages by loosing on other parameters. With a dipole bass You´re loosing on simplicity. With this I mean, that it is easier and cheaper to build a box and cut one or two holes in it than to build a special structure for 4 drivers.
I know Axel and his partners for some years now and worked with them and can say that roundabout a dipole with 4 drivers (serial-parallel-connected) behaves similarly as a single driver CB or BR with regard to volume and SPL.
Still the dipole will exhibit deeper bass than a CB and much less group delay than BR and less excitation of room modes, i.e it has more degrees of freedom in setting up the system.
jauu
Calvin
ps:
"I've used the ripole concept but with W manifolds and a U-baffle extension on the back" Even though it might look very similar, this doesn´t apply for, since the idea and concept of the ripoles is extreme compactness together with a distinct reduction of the drivers free air resonance. The W-baffle ala Linkwitz claims a reduction of odd harmonics, by having the drivers connected out of phase electrically. But in difference to the BMC-ripole where both drivers work in symmetry, the W-style drivers work under different conditions (3 different chambers -hence no symmetry) thereby swapping any advantage its different driver connection could exhibit with regard to distortion (imo).
Re: No offense
Calvin,
I can't argue the compactness point, although with large drivers the ripole can't be much, if any, narrower than the 9-10" I'm planning. I do, however, believe symmetry is possible with a W alignment using multiples of 4 drivers despite having one forward pathway and two smaller identical reward pathways. It just takes careful planning, especially with minimum width as a goal to reduce Fs and size.
Calvin said:
Calvin,
I can't argue the compactness point, although with large drivers the ripole can't be much, if any, narrower than the 9-10" I'm planning. I do, however, believe symmetry is possible with a W alignment using multiples of 4 drivers despite having one forward pathway and two smaller identical reward pathways. It just takes careful planning, especially with minimum width as a goal to reduce Fs and size.
Hi,
its not a matter of believe
Using the same drivers the BMC-ripole is the smallest possible and its symmetric...point!Just compare whats comparable.
In W-baffle there can´t be symmetry, because not only face the front- and backsides of the two drivers different volumes (as they do also in BMC), but those volumes are different for each driver too, or short in BMC 2 drivers face 2 different volumes, in W-baffle they face 3 different volumes.
jauu
Calvin
its not a matter of believe
Using the same drivers the BMC-ripole is the smallest possible and its symmetric...point!Just compare whats comparable. In W-baffle there can´t be symmetry, because not only face the front- and backsides of the two drivers different volumes (as they do also in BMC), but those volumes are different for each driver too, or short in BMC 2 drivers face 2 different volumes, in W-baffle they face 3 different volumes.
jauu
Calvin
How critical are the parameters for a ripole?
Is there any particular reason why the SLS drivers are popular for this application?
I'd like to hear comments on how ripoles compare to other dipoles in terms of SQ. It seems to me a big disadvantage is the small openings causing resonances and restricting upper limit compared to a H frame or U frame design.
I'm currently trying out U frames, having tried H frames. The U frame does seem to radiate more bass to the room.
Is there any particular reason why the SLS drivers are popular for this application?
I'd like to hear comments on how ripoles compare to other dipoles in terms of SQ. It seems to me a big disadvantage is the small openings causing resonances and restricting upper limit compared to a H frame or U frame design.
I'm currently trying out U frames, having tried H frames. The U frame does seem to radiate more bass to the room.
Yes, definitely, commentary on relative SQ, please.
John, I found a new set of Durabrand 6"x9"s at Walmart last night for $20 a pair. These are ostensibly 4-way, though really its just a mid and then a pair of identical tweeters, one mounted on either side. I had been going to grab a pair of the old style ones ($10 each, actually sold singly) which look very much like my Kenwoods (same looking frame, very similar foam surround, but a much smaller mylar whizzer instead of the larger paper one on the Kens and a dark gray cone instead of a silver gray one). These new ones, though had rubber surrounds and 30oz strontium magnets (as opposed to 10oz on the old style ones), so for the same price seemed much more useful. I haven't had a chance to test them yet, but they obviously have much more Xmax than my Kens.
I'm actually looking to use build them into a set of stacked ripoles, drivers mounted vertically to minimize the footprint. I've got a corner space I can fill to the ceiling if need be, and I'm figuring I can build to about 8"x8" and get away with using standard board sizes and minimal woodworking. I may go with 8 drivers total at some point, but I'm going to play with this pair for a bit to see how they perform, then figure how I can disassemble them for my subwoofer purposes and build a 2 driver unit to start.
Are there any guides for building ripoles? Any rules about how much space on either side of the driver? I was just thinking to pad the back of the magnet and press the back board up against that for rigidity and then make identical spacing in front. Will that work? And what sort of Fs lowering can one expect from a ripole? Is there any way to calculate it, or perhapse control it by variations on its construction?
Kensai
John, I found a new set of Durabrand 6"x9"s at Walmart last night for $20 a pair. These are ostensibly 4-way, though really its just a mid and then a pair of identical tweeters, one mounted on either side. I had been going to grab a pair of the old style ones ($10 each, actually sold singly) which look very much like my Kenwoods (same looking frame, very similar foam surround, but a much smaller mylar whizzer instead of the larger paper one on the Kens and a dark gray cone instead of a silver gray one). These new ones, though had rubber surrounds and 30oz strontium magnets (as opposed to 10oz on the old style ones), so for the same price seemed much more useful. I haven't had a chance to test them yet, but they obviously have much more Xmax than my Kens.
I'm actually looking to use build them into a set of stacked ripoles, drivers mounted vertically to minimize the footprint. I've got a corner space I can fill to the ceiling if need be, and I'm figuring I can build to about 8"x8" and get away with using standard board sizes and minimal woodworking. I may go with 8 drivers total at some point, but I'm going to play with this pair for a bit to see how they perform, then figure how I can disassemble them for my subwoofer purposes and build a 2 driver unit to start.
Are there any guides for building ripoles? Any rules about how much space on either side of the driver? I was just thinking to pad the back of the magnet and press the back board up against that for rigidity and then make identical spacing in front. Will that work? And what sort of Fs lowering can one expect from a ripole? Is there any way to calculate it, or perhapse control it by variations on its construction?
Kensai
Calvin,
Symmetry IS possible with a W manifold using multiples of 4 drivers. 2 identical rear pathways (same # of cones, same # of baskets, equal width, equal air mass) combined with double width of the front pathway having double the cones and baskets means double the air mass, and 1 + 1 = 2 = symmetry. The real difference is that you are limited on the minimum width of the single pathway due to the magnet to cone orientation of the drivers unless you want to give up push/pull.
Paul,
I can't comment on Ripole specifically, but I can on any manifold vs direct radiation. Sound waves want to be round and originating a wave from a straight slot inherently has to cause distortion in the wavefront vs direct radiation from the cone. Second, and I believe more important, is the difference in how the wave originates. With any manifold the piston pushes against a restricted volume of air, which pushes a pressure front through a slot before it can start to convert to wave form. These create an audible difference, not a huge one but it's there in the form of a hint of mushiness compared to the direct radiation of H's, U's, or flat baffle OB's.
Kensai,
Once you start folding an OB of any form, the critical dimension becomes depth, and an 8" deep ripole will start rolling off quite early, 287hz in free space. Regarding lowering Fs, Ripole pathways widths etc, start with studying the ripole thread. Construction is discussed there too, but I'll give you a hint. The overall width of a ripole can be as little as the mounting depth of 1 driver plus the width of the 2 pathways. The thicker the driver mounting baffle, the narrow the ripole, and you can further reduce width by cutting holes in the side panels for the driver magnets. The thicker driver mounting baffle didn't dawn on me until recently, otherwise I would have been able to reduce the width of my W-Baffle using 4 12's to only 10-10.5".
Symmetry IS possible with a W manifold using multiples of 4 drivers. 2 identical rear pathways (same # of cones, same # of baskets, equal width, equal air mass) combined with double width of the front pathway having double the cones and baskets means double the air mass, and 1 + 1 = 2 = symmetry. The real difference is that you are limited on the minimum width of the single pathway due to the magnet to cone orientation of the drivers unless you want to give up push/pull.
Paul,
I can't comment on Ripole specifically, but I can on any manifold vs direct radiation. Sound waves want to be round and originating a wave from a straight slot inherently has to cause distortion in the wavefront vs direct radiation from the cone. Second, and I believe more important, is the difference in how the wave originates. With any manifold the piston pushes against a restricted volume of air, which pushes a pressure front through a slot before it can start to convert to wave form. These create an audible difference, not a huge one but it's there in the form of a hint of mushiness compared to the direct radiation of H's, U's, or flat baffle OB's.
Kensai,
Once you start folding an OB of any form, the critical dimension becomes depth, and an 8" deep ripole will start rolling off quite early, 287hz in free space. Regarding lowering Fs, Ripole pathways widths etc, start with studying the ripole thread. Construction is discussed there too, but I'll give you a hint. The overall width of a ripole can be as little as the mounting depth of 1 driver plus the width of the 2 pathways. The thicker the driver mounting baffle, the narrow the ripole, and you can further reduce width by cutting holes in the side panels for the driver magnets. The thicker driver mounting baffle didn't dawn on me until recently, otherwise I would have been able to reduce the width of my W-Baffle using 4 12's to only 10-10.5".
Hi,
I still disagree with John about symmetry. Since You are using conical diaphragms, the volumes of the chambers will still differ even with same dimensions. Apart from that the size of such a dipole is always bigger than a BMC-ripole and the optics are imo
I guess with SQ is meant sound quality? Well there´s no reason it should be inferior to other dipoles within the reasonable freqency range. This range is restricted to below ~200Hz with small drivers and sinking with big drivers.
The SLS of Peerless are some of the best and payable drivers You could get for dipoles. They feature a close to ideal set of parameters and a progressive spider. They work with low distortion and noise and don´t need much equalization of deep bass and they are nearly indestructable.
For construction details please search in the archives! It has been more than enough been discussed to be repeated here again
(dipole-ripole- BMC-DRS and other search phrases)
jauu
Calvin
I still disagree with John about symmetry. Since You are using conical diaphragms, the volumes of the chambers will still differ even with same dimensions. Apart from that the size of such a dipole is always bigger than a BMC-ripole and the optics are imo
I guess with SQ is meant sound quality? Well there´s no reason it should be inferior to other dipoles within the reasonable freqency range. This range is restricted to below ~200Hz with small drivers and sinking with big drivers.
The SLS of Peerless are some of the best and payable drivers You could get for dipoles. They feature a close to ideal set of parameters and a progressive spider. They work with low distortion and noise and don´t need much equalization of deep bass and they are nearly indestructable.
For construction details please search in the archives! It has been more than enough been discussed to be repeated here again
(dipole-ripole- BMC-DRS and other search phrases)
jauu
Calvin
Calvin said:
Only because you aren't thinking it all the way through. I said multiples of 4 drivers, bottom pair facing one direction, top pair facing the other....symmetrical and vibration cancellation too. Cancelling the mechanics is probably more important than perfect symmetry because the unit is typically used as the base for the main driver(s). Why someone would want the "Swaying Tower of Ripole" as a speaker base is beyond me. I want form & function, not form over function.
Apart from that the size of such a dipole is always bigger than a BMC-ripole and the optics are imo
jauu
Calvin
Typically maybe, but not always. What I'm planning will be smaller, better looking, better sounding, and more flexible than its equivalent ripole which would require a pair of 15's. I'll post pics in a month or so when it's done.
Yes that's right re SQ
I was hoping for more of an opinion either based on theory, or more preferably based on AB listening tests where the only thing changed was the box.
I see reason why they would compromise SQ. I tend to agree with John, although I have not tried or heard a ripole yet. A more open H frame seems likely to have less severe resonances. Also the ripole has the driver in a constricted airspace and I suspect the air inside will behave differently.
Hi,
of course did I read Your post John, but You won´t achieve symmetry by stacking asymmetric dipoles. With a W-dipole You can have either equal chamber values -which means different opening areas of te flares- or equal dimensions of the chambers -with different volumes, cause of the drivers conical diaphragm shapes. Thats a fact.
And in case You haven´t read my post thoroughly: I was talking about a BMC-dipole (I rather dislike to call it ripole, because the original names are BMC for a symmetrical 2-driver- and DRS for a asymmetrical 1-driver-dipole after Ridthaler) in which symmetry is inherent. With this design force-cancellation is inherent too.
If You use stacked asymmetric DRS-dipoles with every second turned 180° (eg. 4,6 or 8) theire forces will cancel out too to a large degree -the more stacked, the better cancellation.
Symmetry is -again I have to disagree to John- more important than turning the drivers 180°- and thats not a matter of probability but a result measurements and of years of experience with a few dozens of such subs -subs by Axel and his partners as well as my own designs and those of others. The same holds true for the sonic results. Sonic differences between different Dipole-styles are mostly swapped by room interaction and positioning and the second most important point are the drivers. The sonic differences between W and BMC-dipole are relativley negligible compared to the afore mentioned points.
I´m happy to see that You John are a very selfconfident person, but to me Your claim of designing a dipole-sub that is even smaller than a BMC and better in nearly every regard is taking Your mouth too full. Especially since Your design at the moment has just the status of wishful thinking or beeing in built, whereas the BMCs are excellently working real products for many years now. More so, since I´m quite shure, that You haven´t heard a original BMC by AE under good conditions. I´m very eager though to see measurements of Your little beast.
Just to give You an idea, what we are talking about:
BMC 400:
34cm W 46cm H 46cm D (13.4"x18.12x18.1")
This size is even smaller than a pair of shipping cartonage of the used drivers! (And this holds true for every size of driver, not just the 15"!)
Fs: 16-18Hz (depending on filter) and a very linear amplitude response
SPL max: >112db@>45Hz
Sound was tested as excellent and state of the art from several German HiFi magazines (of which just one AE advertised in
jauu
Calvin
of course did I read Your post John, but You won´t achieve symmetry by stacking asymmetric dipoles. With a W-dipole You can have either equal chamber values -which means different opening areas of te flares- or equal dimensions of the chambers -with different volumes, cause of the drivers conical diaphragm shapes. Thats a fact.
And in case You haven´t read my post thoroughly: I was talking about a BMC-dipole (I rather dislike to call it ripole, because the original names are BMC for a symmetrical 2-driver- and DRS for a asymmetrical 1-driver-dipole after Ridthaler) in which symmetry is inherent. With this design force-cancellation is inherent too.
If You use stacked asymmetric DRS-dipoles with every second turned 180° (eg. 4,6 or 8) theire forces will cancel out too to a large degree -the more stacked, the better cancellation.
Symmetry is -again I have to disagree to John- more important than turning the drivers 180°- and thats not a matter of probability but a result measurements and of years of experience with a few dozens of such subs -subs by Axel and his partners as well as my own designs and those of others. The same holds true for the sonic results. Sonic differences between different Dipole-styles are mostly swapped by room interaction and positioning and the second most important point are the drivers. The sonic differences between W and BMC-dipole are relativley negligible compared to the afore mentioned points.
I´m happy to see that You John are a very selfconfident person, but to me Your claim of designing a dipole-sub that is even smaller than a BMC and better in nearly every regard is taking Your mouth too full. Especially since Your design at the moment has just the status of wishful thinking or beeing in built, whereas the BMCs are excellently working real products for many years now. More so, since I´m quite shure, that You haven´t heard a original BMC by AE under good conditions. I´m very eager though to see measurements of Your little beast.
Just to give You an idea, what we are talking about:
BMC 400:
34cm W 46cm H 46cm D (13.4"x18.12x18.1")
This size is even smaller than a pair of shipping cartonage of the used drivers! (And this holds true for every size of driver, not just the 15"!)
Fs: 16-18Hz (depending on filter) and a very linear amplitude response
SPL max: >112db@>45Hz
Sound was tested as excellent and state of the art from several German HiFi magazines (of which just one AE advertised in
An externally hosted image should be here but it was not working when we last tested it.
jauu
Calvin
Calvin,
It took some time searching around to find your BMC 400, and what a waste of time. That's just a W-baffle woofer http://www.audioelevation.de/attac_400.htm# , so I really don't understand what you are disputing other than the minor point of Linkwitz using push/pull. In fact, the BMC design has less symmetry than Linkwitz's if you adjust his dimensions to equally air mass load both sides of the cones. BMC's doesn't have front to back symmetry, since as you stated, the front and rear radiation of a driver are not identical. I wasn't touting Linkwitz's design anyway. This is all irrelevant, because Kensai wants compact and 14" wide (correct width 36cm) isn't compact at all for a speaker base.
Also, please stop calling these things subwoofers and don't go quoting max SPL#'s without including the assumptions because that 112db at 45hz is optimistic even with half space loading. Assuming the 112db is accurate, why quote a max spl at 45hz, but show a beautiful response graph to 20hz, especially since the excursion limited max is only 97db at 25hz and 91db at 20hz? That's without considering that dipoles roll off steeply below the significant room mode, making them all but useless as a true subwoofer.
It took some time searching around to find your BMC 400, and what a waste of time. That's just a W-baffle woofer http://www.audioelevation.de/attac_400.htm# , so I really don't understand what you are disputing other than the minor point of Linkwitz using push/pull. In fact, the BMC design has less symmetry than Linkwitz's if you adjust his dimensions to equally air mass load both sides of the cones. BMC's doesn't have front to back symmetry, since as you stated, the front and rear radiation of a driver are not identical. I wasn't touting Linkwitz's design anyway. This is all irrelevant, because Kensai wants compact and 14" wide (correct width 36cm) isn't compact at all for a speaker base.
Also, please stop calling these things subwoofers and don't go quoting max SPL#'s without including the assumptions because that 112db at 45hz is optimistic even with half space loading. Assuming the 112db is accurate, why quote a max spl at 45hz, but show a beautiful response graph to 20hz, especially since the excursion limited max is only 97db at 25hz and 91db at 20hz? That's without considering that dipoles roll off steeply below the significant room mode, making them all but useless as a true subwoofer.
pinkmouse said:
Guys, calm down.
????
Pinkmouse,
Are people not allowed to disagree and make points regarding why they disagree? I don't see anything here getting heated or personal, so I really don't understand the police reprimand. Calvin and I don't agree on some things. I don't think he's bothered or offended, and I know I'm not. I tried to edit my "waste of time" remark, but it was too late and the system didn't allow an edit.
John, I accept your comments, and I understand where you are coming from. But for someone not previously involved in this thread, it does come across as getting slightly heated, and about to descend to the personal level. If you go back and read it with an unbiased eye you'll see what I mean.
???? Still No ;-)
Hi,
"Thats just a W-baffle". You might call it as such, right.
SL uses this term for his constructions, but Axel called it the BMC, since his aims were different ones (compactness and lower fs). As a matter of fact, both made they´re developements quite at the same time. So any thought that one of both had copied the other´s stuff is a wrong guess. Since there are small but distinct differences in design, I prefer to name the BMC BMC and the W-baffle W-baffle. You wouldn´t call a BigMac a Double-Whopper just because both are made from some meat and loaf would You? Interestingly the guys know each other and what they do and -to my knowledge- never had a argument about who´s first or who might have copied the other´s thoughts. They leave the discussion to us weirdos and stick with important matters
John´s equally right in claiming front-back-asymmetry. But is this symmetry of any use at all? It is not, since both volumes the diaphragm sees, are coupled with each other through the diaphragm. The diaphragm doesn´t know which side is front and which is back, it sees just one (combined) load. We can turn the diaphragm 180° without any difference at all (effects of the driver itself neglected hereby). Would it be different SLs woofer wouldn´t make sense, as well as every other box wouldn´t. Solely the drivers own (mis-) behaviour is the reason for turning one of the two drivers 180° around. I agree that it´s a smart idea to turn one driver around to cancel a part of theyre distortion. But to my experience the gain of this measurement is not audible and it is swapped by the effect of differently loaded drivers and -to my taste- inferior optics.
Important is that both speakers see equal loads, so they can work equally. And this is the strong and obvious point of the BMC.
It´s my strong opinion to call the BMCs subwoofers, as is anybody else´s opinion I know of who´s heard them. In fact, because of its folding its restricted to subwoofer-use!
I´ll go on quoting measurements as I wish -preferrably ones that everybody else could check for correctness.
At least there are some open and independent measurements for the BMC. Where are Your´s John???
The amplitude response and the SPL figure for example were taken at Stereo´s and Stereoplay´s measurement laboratories and were printed in tests. I could have given some own measurements but I preferred something more ´official´
The reason for giving an the SPL-quote @45Hz and not @20Hz could be best explained by the magazine, but I think that
a) 45Hz is a reasonable low limit for normal music use and
b) most compact subwoofers have a low-end bandwidth around 40-50Hz, just the bigger ones reach lower. So 2/3rd of the contestants wouldn´t have reached 30Hz or even 20Hz (as the magazines are promotion-instruments, You can´t allow for printing specs that show the product´s problematics)
As far as I remind they measured the SPL for a given freq when a certain level of distortion was reached (I´m think it was 3%, but I´m not sure about that)
Compactness is a relative value. Well John, if You think You´d be able to build a even more compact woofer featuring 2 15" drivers go ahead. If using drivers of different size You´d hardlyget similar performance results. I think we all would like to see those results
jauu
Calvin
Hi,
"Thats just a W-baffle". You might call it as such, right.
SL uses this term for his constructions, but Axel called it the BMC, since his aims were different ones (compactness and lower fs). As a matter of fact, both made they´re developements quite at the same time. So any thought that one of both had copied the other´s stuff is a wrong guess. Since there are small but distinct differences in design, I prefer to name the BMC BMC and the W-baffle W-baffle. You wouldn´t call a BigMac a Double-Whopper just because both are made from some meat and loaf would You? Interestingly the guys know each other and what they do and -to my knowledge- never had a argument about who´s first or who might have copied the other´s thoughts. They leave the discussion to us weirdos and stick with important matters
John´s equally right in claiming front-back-asymmetry. But is this symmetry of any use at all? It is not, since both volumes the diaphragm sees, are coupled with each other through the diaphragm. The diaphragm doesn´t know which side is front and which is back, it sees just one (combined) load. We can turn the diaphragm 180° without any difference at all (effects of the driver itself neglected hereby). Would it be different SLs woofer wouldn´t make sense, as well as every other box wouldn´t. Solely the drivers own (mis-) behaviour is the reason for turning one of the two drivers 180° around. I agree that it´s a smart idea to turn one driver around to cancel a part of theyre distortion. But to my experience the gain of this measurement is not audible and it is swapped by the effect of differently loaded drivers and -to my taste- inferior optics.
Important is that both speakers see equal loads, so they can work equally. And this is the strong and obvious point of the BMC.
It´s my strong opinion to call the BMCs subwoofers, as is anybody else´s opinion I know of who´s heard them. In fact, because of its folding its restricted to subwoofer-use!
I´ll go on quoting measurements as I wish -preferrably ones that everybody else could check for correctness.
At least there are some open and independent measurements for the BMC. Where are Your´s John???
The amplitude response and the SPL figure for example were taken at Stereo´s and Stereoplay´s measurement laboratories and were printed in tests. I could have given some own measurements but I preferred something more ´official´
The reason for giving an the SPL-quote @45Hz and not @20Hz could be best explained by the magazine, but I think that
a) 45Hz is a reasonable low limit for normal music use and
b) most compact subwoofers have a low-end bandwidth around 40-50Hz, just the bigger ones reach lower. So 2/3rd of the contestants wouldn´t have reached 30Hz or even 20Hz (as the magazines are promotion-instruments, You can´t allow for printing specs that show the product´s problematics)
As far as I remind they measured the SPL for a given freq when a certain level of distortion was reached (I´m think it was 3%, but I´m not sure about that)
Compactness is a relative value. Well John, if You think You´d be able to build a even more compact woofer featuring 2 15" drivers go ahead. If using drivers of different size You´d hardlyget similar performance results. I think we all would like to see those results
jauu
Calvin
Calvin,
We'll just have to agree to disagree. 45hz is a ridiculous place to quote max spl for an in home sub. We both know why it was quoted that way....only to mislead. If 45hz is all that's needed, then why include a response graph with low pass filters at 40hz and 65hz?
"W-baffle" is a shape, not a name, just like an H-baffle or N-baffle. Call your BMC whatever you want. It's still a W from my point of view.
I suggest once again that you need to read posts more closely, or stop trying to twist my words around to something different than was said. Maybe it's just a language barrier problem, but I doubt it.
We'll just have to agree to disagree. 45hz is a ridiculous place to quote max spl for an in home sub. We both know why it was quoted that way....only to mislead. If 45hz is all that's needed, then why include a response graph with low pass filters at 40hz and 65hz?
"W-baffle" is a shape, not a name, just like an H-baffle or N-baffle. Call your BMC whatever you want. It's still a W from my point of view.
I suggest once again that you need to read posts more closely, or stop trying to twist my words around to something different than was said. Maybe it's just a language barrier problem, but I doubt it.
Hi,
I strongly agree John but just one point.
Its not my purpose to twist anybody´s words and I actually don´t know to what passage You are referring to.
I think I clearly stated where the two principles have their distinct differences. Wether someone does not get the point or prefers to neglect the differences between ´Macs and Burgers´ ...well, I don´t care much about that. But as long as someone neglects common terms and speaks with his own tongue, he shouldn´t wonder when misunderstandings occur. Anyway there will be enough guys around who will draw the right conclusions.
I won´t discuss either on this basis if a test-magazine does a sensible measurement job or not. Anybody slightly skilled in designing Audio will be able to judge if the numbers are practical and helpful or not.
I think I´ll relax a bit more as pinkmouse kindly suggested, secure in the knowledge that many guys have confidently built excellent dipole-subs with a little help from my suggestions and I´ll wait for the supercompact superduper bass from Costa Rica 
There have been already so many, who thought they´d have found the ultimate catch22, but in the end ...... Well, ...show us all where the ropes hang. I for my part wish You much luck with Your project.
jauu
Calvin
I strongly agree John
but just one point.Its not my purpose to twist anybody´s words and I actually don´t know to what passage You are referring to.
I think I clearly stated where the two principles have their distinct differences. Wether someone does not get the point or prefers to neglect the differences between ´Macs and Burgers´ ...well, I don´t care much about that. But as long as someone neglects common terms and speaks with his own tongue, he shouldn´t wonder when misunderstandings occur. Anyway there will be enough guys around who will draw the right conclusions.
I won´t discuss either on this basis if a test-magazine does a sensible measurement job or not. Anybody slightly skilled in designing Audio will be able to judge if the numbers are practical and helpful or not.
I think I´ll relax a bit more as pinkmouse kindly suggested, secure in the knowledge that many guys have confidently built excellent dipole-subs with a little help from my suggestions
and I´ll wait for the supercompact superduper bass from Costa Rica There have been already so many, who thought they´d have found the ultimate catch22, but in the end ...... Well, ...show us all where the ropes hang. I for my part wish You much luck with Your project.
jauu
Calvin
Calvin,
Can we at least agree to get the terminology straight, so others don't fall into the same trap? BTW, while Big Macs and Whoppers are different things, they are both hamburgers. Agreeing on terminology now is important because OB's are still on the fringes of audio, but they are rapidly becoming accepted into the mainstream, at least in the DIY community, and many new commercial units have become available in the past 2 years. Hopefully this will avoid future confusion. Anyone, please correct me where you disagree.
Open Baffle (OB) speaker- Any speaker where the front and rear radiation from the driver are open to the room without harnessing the rear wave energy in some kind of chamber to change it's output such as a bass reflex, Tline, or rear horn.
Dipole speaker- An OB speaker where the front and rear output are equal and the front and rear pathways are effectively the same. The result is a figure 8 radiation pattern with the area of greatest null 90 degrees from the axis of the speaker. In it's simplest form a driver is mounted to a flat baffle. If the baffle is folded into shapes such as H-baffles, N-baffles, or W-baffles, the front and rear wave pathway distances need to be the same to achieve pure dipole radiation. For all the science behind dipoles the best resource is http://linkwitzlab.com
U-baffle - An OB where the path from the rear of the driver to the front of the speaker is a substantially longer distance than the front of the driver to the rear of the speaker. In it's purest form, the pathway distance difference for the front and rear radiation would be 0 at the rear of the speaker. This will result in a cardoid radiation pattern with the the area of greatest null on axis directly centered behind the speaker. U-baffles have a 6db advantage on axis over the same sized folded dipoles in the lower frequencies because they have double the pathway distance for the rear wave. For the science behind U-baffles see http://musicanddesign.com/tech.html
N and W baffle woofers and subwoofers are OB's with baffles shaped like their name. Typically the baffle is formed by 90 degree folds. The drivers are mounted so that the front and rear driver output flow into pathways exiting the front and rear of the speaker. Their primary benefit is a more compact visual size, and the W alignment has the additional benefit of cancelling out the mechanical forces of the drivers' operation within the cab itself, leaving only the mass of air moved as the only net force on the cab.
Ripole- An N or W baffle dipole woofer or subwoofer where the pathways are shrunk to a suggested 25-30% of the driver(s) Sd in a manner so that both sides of the cone are equally air mass loaded. The result is a lowering of Fs by an estimated 10-15hz. The primary benefit is the ripole's very small size in relation to other dipole woofers. While sensitivity is significantly lower in a ripole alignment, maximum output should remain unchanged, because, as will all OB's, low frequency output is usually limited by excursion, not the driver's thermal limits.
BMC (Blow Motion Concept)- Is a patented W-baffle alignment sold by Audio Elevation (see http://www.audioelevation.de ), which combines the ripole approach with a W shaped baffle in a push-push alignment with the resulting "sub"woofers taking cab size to the lowest limit using those drivers.
Linkwitz W-baffle Woofer- Is a W-baffle dipole woofer originally designed to supplement the bass performance in Siegfried Linkwitz's Phoenix dipole speaker system. It uses a push/pull driver alignment to cancel distortion resulting from the non-linear operation difference between the "push" and the "pull" of the driver cone. Construction details of his woofer are shared here http://linkwitzlab.com/woofer.htm .
Can we at least agree to get the terminology straight, so others don't fall into the same trap? BTW, while Big Macs and Whoppers are different things, they are both hamburgers. Agreeing on terminology now is important because OB's are still on the fringes of audio, but they are rapidly becoming accepted into the mainstream, at least in the DIY community, and many new commercial units have become available in the past 2 years. Hopefully this will avoid future confusion. Anyone, please correct me where you disagree.
Open Baffle (OB) speaker- Any speaker where the front and rear radiation from the driver are open to the room without harnessing the rear wave energy in some kind of chamber to change it's output such as a bass reflex, Tline, or rear horn.
Dipole speaker- An OB speaker where the front and rear output are equal and the front and rear pathways are effectively the same. The result is a figure 8 radiation pattern with the area of greatest null 90 degrees from the axis of the speaker. In it's simplest form a driver is mounted to a flat baffle. If the baffle is folded into shapes such as H-baffles, N-baffles, or W-baffles, the front and rear wave pathway distances need to be the same to achieve pure dipole radiation. For all the science behind dipoles the best resource is http://linkwitzlab.com
U-baffle - An OB where the path from the rear of the driver to the front of the speaker is a substantially longer distance than the front of the driver to the rear of the speaker. In it's purest form, the pathway distance difference for the front and rear radiation would be 0 at the rear of the speaker. This will result in a cardoid radiation pattern with the the area of greatest null on axis directly centered behind the speaker. U-baffles have a 6db advantage on axis over the same sized folded dipoles in the lower frequencies because they have double the pathway distance for the rear wave. For the science behind U-baffles see http://musicanddesign.com/tech.html
N and W baffle woofers and subwoofers are OB's with baffles shaped like their name. Typically the baffle is formed by 90 degree folds. The drivers are mounted so that the front and rear driver output flow into pathways exiting the front and rear of the speaker. Their primary benefit is a more compact visual size, and the W alignment has the additional benefit of cancelling out the mechanical forces of the drivers' operation within the cab itself, leaving only the mass of air moved as the only net force on the cab.
Ripole- An N or W baffle dipole woofer or subwoofer where the pathways are shrunk to a suggested 25-30% of the driver(s) Sd in a manner so that both sides of the cone are equally air mass loaded. The result is a lowering of Fs by an estimated 10-15hz. The primary benefit is the ripole's very small size in relation to other dipole woofers. While sensitivity is significantly lower in a ripole alignment, maximum output should remain unchanged, because, as will all OB's, low frequency output is usually limited by excursion, not the driver's thermal limits.
BMC (Blow Motion Concept)- Is a patented W-baffle alignment sold by Audio Elevation (see http://www.audioelevation.de ), which combines the ripole approach with a W shaped baffle in a push-push alignment with the resulting "sub"woofers taking cab size to the lowest limit using those drivers.
Linkwitz W-baffle Woofer- Is a W-baffle dipole woofer originally designed to supplement the bass performance in Siegfried Linkwitz's Phoenix dipole speaker system. It uses a push/pull driver alignment to cancel distortion resulting from the non-linear operation difference between the "push" and the "pull" of the driver cone. Construction details of his woofer are shared here http://linkwitzlab.com/woofer.htm .
Where I see the real opportunity in advancing OB design is in hydrid enclosures. I don't mean combining OB with a box for enhanced bass. That gives up too many benefits related to OB bass. I mean hybrids somewhere in between pure dipole alignments and a pure U-baffle. The result is some of the enhanced bass performance and smaller size of a U-baffle, without losing the room interaction benefits of dipole.
John,
This is regarding a pair of fullrangers, but this looked like the best discussion to drop the concept into. They are currently on flat OBs that are in need of being redone, anyway, so I'm looking for ways to improve bass response in the process.
The concept I'm thinking of will basically be a ~16" wide, ~12" tall box that is just deep enough to mount the drivers, but with a cutout for the magnet on the rear panel so that the spacing between baffle and rear panel is minimized, as in a ripole alignment. However, the front will simply be this flat baffle. The driver will be mounted to the outside edge of this 16" wide baffle, and the narrow edge opposite that will be the open side (this open edge will also be where I hinge mount them to my desk).
How do you think this will behave? Will it simply be an oddly aligned U baffle? Will it achieve partial ripole effects. Will it absolutely suck due to the differing air pressure on either side of the driver? Would I be better off making the enclosure a bit deeper to give the driver more "breathing" room to avoid any unpleasantness and just accept the U baffle effect?
Kensai
This is regarding a pair of fullrangers, but this looked like the best discussion to drop the concept into. They are currently on flat OBs that are in need of being redone, anyway, so I'm looking for ways to improve bass response in the process.
The concept I'm thinking of will basically be a ~16" wide, ~12" tall box that is just deep enough to mount the drivers, but with a cutout for the magnet on the rear panel so that the spacing between baffle and rear panel is minimized, as in a ripole alignment. However, the front will simply be this flat baffle. The driver will be mounted to the outside edge of this 16" wide baffle, and the narrow edge opposite that will be the open side (this open edge will also be where I hinge mount them to my desk).
How do you think this will behave? Will it simply be an oddly aligned U baffle? Will it achieve partial ripole effects. Will it absolutely suck due to the differing air pressure on either side of the driver? Would I be better off making the enclosure a bit deeper to give the driver more "breathing" room to avoid any unpleasantness and just accept the U baffle effect?
Kensai
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