The eminence 15a pro kappa, but it was bested by the jbl. It is just for midbass down to 80Hz. This the "weak" cone should handle. I am looking for something with more extension into the midrange but with the same specs.
Last edited:
BMR 4.5 inch Neo driver with silk surround
Hi POOH,
The Bending Mode Radiator (BMR) is a full range (40Hz to 15KHz) driver which produces most of its audio output via controlled flexing or bending of a flat honeycomb diaphragm rather than the conventional "push pull" (erroneously described as "pistonic" by driver manufacturers to mislead buyers) motion of cones and domes.
The BMR driver offers three main advantages over push pull drivers:
(1) Speed.
BMR rise and settling time are superb when compared to push pull drivers.
(2) Dispersion.
Both horizontal and vertical dispersion are broad and even : Typically 150 degrees to 160 degrees.
This enables true "point source" reproduction when used in singles and virtual point source when crossed over at 80Hz to a sub woofer or bass driver to increase power handling.
Personally I like audio ( music and movies) with a broad dynamic range and high SPL capability so single driver point sources are not enough for me.
So I am very excited about the third advantage...
(3) Line array and or panel compatibility:
When combined with on wall or in wall speaker cabinet placement the broad dispersion of the drivers combine naturally with the advantages of line array and panel design, increasing power handling and sensitivity up to Pro driver levels.
Full range ( no crossovers) and broad dispersion combined with on wall placement results in genuine room filling sound which works with the room and not against it....No need for horns / waveguides to limit directivity to avoid reflections ....The arrays flood the room with a naturally balanced sound which we perceive much as we would perceive " the real thing"
All the best
Derek.
Hi POOH,
The Bending Mode Radiator (BMR) is a full range (40Hz to 15KHz) driver which produces most of its audio output via controlled flexing or bending of a flat honeycomb diaphragm rather than the conventional "push pull" (erroneously described as "pistonic" by driver manufacturers to mislead buyers) motion of cones and domes.
The BMR driver offers three main advantages over push pull drivers:
(1) Speed.
BMR rise and settling time are superb when compared to push pull drivers.
(2) Dispersion.
Both horizontal and vertical dispersion are broad and even : Typically 150 degrees to 160 degrees.
This enables true "point source" reproduction when used in singles and virtual point source when crossed over at 80Hz to a sub woofer or bass driver to increase power handling.
Personally I like audio ( music and movies) with a broad dynamic range and high SPL capability so single driver point sources are not enough for me.
So I am very excited about the third advantage...
(3) Line array and or panel compatibility:
When combined with on wall or in wall speaker cabinet placement the broad dispersion of the drivers combine naturally with the advantages of line array and panel design, increasing power handling and sensitivity up to Pro driver levels.
Full range ( no crossovers) and broad dispersion combined with on wall placement results in genuine room filling sound which works with the room and not against it....No need for horns / waveguides to limit directivity to avoid reflections ....The arrays flood the room with a naturally balanced sound which we perceive much as we would perceive " the real thing"
All the best
Derek.
Attachments
OK, i recommend the Electro Voice EVM15 L or B they are excellent and very extended. In my experience they are much better then the JBL 2220 in a midbass horn and are usable beyond 1k
BMR stuff
You are welcome!
The theory and patents behind the BMR's are very interesting, sadly most of the production drivers aimed at the mass market for TV's and portable sound applications.
The rare Neo motor versions in the 112mm square chassis are the very best ones and great for DIY dudes!
All the best
Derek.
PS I would love to hear your horn system in a home cinema set up...Its on my bucket list!
Thanks! I will check this out when i get some more free time
You are welcome!
The theory and patents behind the BMR's are very interesting, sadly most of the production drivers aimed at the mass market for TV's and portable sound applications.
The rare Neo motor versions in the 112mm square chassis are the very best ones and great for DIY dudes!
All the best
Derek.
PS I would love to hear your horn system in a home cinema set up...Its on my bucket list!
Can you tell me who makes the 112mm Neo motor version? Googling revealed Tectonic Elements as a manufacturer, but the appearance differs from your image. I wonder who makes the one used in the Naim Ovator series of speakers.
BMR manufacturers
Hi Russell,
Not sure who sells them in Canada or the USA.
Back in 2010 Parts Express was selling a nice 4 inch ( Sd of 50 I think) Neo motor for about $60 I think, but then the price of rare earth neodymium magnets went crazy and Parts Express stopped selling the driver.
Hi Wave / Tectonic Elements / RS Components etc only sell the low grade drivers with no real effort to balance the bending modes...More of random flexing than balanced mode...They also using ferrite magnets and are very small so very low sensitivity and power handling.
In the UK CSS have licenced their own version (see attached) which is available under OEM licence to manufacturers but they don't sell to private individuals or the DIY market.
I have spent 4 years developing two of my own Neo motor 112mm BMR's, a rubber surround version and a double roll silk surround version, and have recently finalised an OEM licence and am waiting on my first production run....Hope to have them in November.
Its a huge commitment (time as well as R&D costs and then £££££ MOQ!) but having heard the prototypes I have no regrets!
Whilst my main target markets will be Pro audio, Custom Install and Commercial AV, I will be offering DIY kits at some point, PM me if you want more info.
All the best
Derek.
Hi Russell,
Not sure who sells them in Canada or the USA.
Back in 2010 Parts Express was selling a nice 4 inch ( Sd of 50 I think) Neo motor for about $60 I think, but then the price of rare earth neodymium magnets went crazy and Parts Express stopped selling the driver.
Hi Wave / Tectonic Elements / RS Components etc only sell the low grade drivers with no real effort to balance the bending modes...More of random flexing than balanced mode...They also using ferrite magnets and are very small so very low sensitivity and power handling.
In the UK CSS have licenced their own version (see attached) which is available under OEM licence to manufacturers but they don't sell to private individuals or the DIY market.
I have spent 4 years developing two of my own Neo motor 112mm BMR's, a rubber surround version and a double roll silk surround version, and have recently finalised an OEM licence and am waiting on my first production run....Hope to have them in November.
Its a huge commitment (time as well as R&D costs and then £££££ MOQ!) but having heard the prototypes I have no regrets!
Whilst my main target markets will be Pro audio, Custom Install and Commercial AV, I will be offering DIY kits at some point, PM me if you want more info.
All the best
Derek.
Derek,
Conventional drivers exhibit cone break up, AKA "controlled flexing or bending".
The cone break up can result in a broad, erratic dispersion pattern which may be as wide as 180 degrees for small drivers. With enough smoothing, it actually can look pretty smooth.
Do you have any unsmoothed polar plots to back up your claim of the BMR's "even" 150 degree dispersion?
I'd also like to see the polars of the 4x4 arrangement, that certainly would look "interesting"
.Of course, even if the BMR does have even polar response, the wide dispersion claimed is the antithesis of Lynn's design using a HF horn that progressively narrows at high frequencies.
Art
BMR's
Lynn, please excuse what may appear as an OT ramble but there is some relevant info here too!
Art, with all due respect, you are way off bass...excuse the pun!
Your thoughts are similar to mine when I first looked at the BMR....
I could not understand how it could sound so good, if I judged it by its TS data and frequency response it was average to poor, that was over 4 years ago...
Now, after investigation into the patents and discussions with the original NXT designers, two years of R&D including a joint venture with a leading UK university, and the last year working directly with the Tymphany driver designers to implement my theories and licence my OEM design I believe I am on the right track.
A few key points are as follows:
(1) There is a gulf of difference between the controlled bending wave motion that is a design feature of a flat honeycomb BMR diaphragm operating within its power handling limits....Vs the uncontrolled bending (cone break up) of a cone or dome as it is pushed beyond its power handling....
(2) On axis frequency response graphs are almost irrelevant....Its how a driver fills a room that counts....A musical instrument does not "beam" or require wave guides or horns to reduce / limit its dispersion pattern....As you walk around a piano or Cello it does not sound different!
(3) Polar measurements are very good as they show the full off axis performance, but they still only show amplitude data....The most important aspect of a BMR (and push / pull drivers IMO) is how it performs in the time domain...Waterfall plots are the single most important measurement one can learn from, I believe they (and similar time domain measurements) hold the key of correlating subjective sound quality with objective measurements.
(4) Its far better to have a driver with a poor frequency response but correct time domain performance.
(5) Its perfectly acceptable (though not ideal) to have a poor on axis frequency response IF the off axis errors are similar ie an even power response. This allows loudspeaker designers the freedom to use DSP....Eq can only be used to fix the frequency response errors when they are even on and off axis!!
(Fab Filter etc are used in 90% of recording / mastering studios) it makes sense to utilise it at the loudspeaker design stage too.)
(6) On or In wall is the best place to locate loudspeakers...In one move this eliminates the most serious room / loudspeaker interface problems...Use the room boundaries / gain to your advantage instead of fighting the room reflections.
(7) Increase Sd and maximise sensitivity....Decrease driver diaphragm movement....Full height floor to ceiling line arrays are the best way to achieve this, 70% of floor to ceiling height is almost as good.
I believe that the above offers a lot of advantages over traditional designs. Also there may well be a way to combine an open baffle bass low midrange (similar to Lynn's design) with either a line array or panel of BMR's....Not sure as I am focusing on my own designs but it's food for thought?
I am waiting on my first production run of drivers, ETA November / December...As soon as I can get them built into the cabinets I will be commissioning a full suite of independent measurements carried out by a top professional. My aim is to have objective data that is beyond question ie accurate and not "cosmetically enhanced" as some manufacturers publish.
By the way, the photo of the 4 BMR's is just to show what they look like...They were sitting on a table not installed in a baffle!!
Hope the above is of interest.
All the best
Derek.
Lynn, please excuse what may appear as an OT ramble but there is some relevant info here too!
Art, with all due respect, you are way off bass...excuse the pun!
Your thoughts are similar to mine when I first looked at the BMR....
I could not understand how it could sound so good, if I judged it by its TS data and frequency response it was average to poor, that was over 4 years ago...
Now, after investigation into the patents and discussions with the original NXT designers, two years of R&D including a joint venture with a leading UK university, and the last year working directly with the Tymphany driver designers to implement my theories and licence my OEM design I believe I am on the right track.
A few key points are as follows:
(1) There is a gulf of difference between the controlled bending wave motion that is a design feature of a flat honeycomb BMR diaphragm operating within its power handling limits....Vs the uncontrolled bending (cone break up) of a cone or dome as it is pushed beyond its power handling....
(2) On axis frequency response graphs are almost irrelevant....Its how a driver fills a room that counts....A musical instrument does not "beam" or require wave guides or horns to reduce / limit its dispersion pattern....As you walk around a piano or Cello it does not sound different!
(3) Polar measurements are very good as they show the full off axis performance, but they still only show amplitude data....The most important aspect of a BMR (and push / pull drivers IMO) is how it performs in the time domain...Waterfall plots are the single most important measurement one can learn from, I believe they (and similar time domain measurements) hold the key of correlating subjective sound quality with objective measurements.
(4) Its far better to have a driver with a poor frequency response but correct time domain performance.
(5) Its perfectly acceptable (though not ideal) to have a poor on axis frequency response IF the off axis errors are similar ie an even power response. This allows loudspeaker designers the freedom to use DSP....Eq can only be used to fix the frequency response errors when they are even on and off axis!!
(Fab Filter etc are used in 90% of recording / mastering studios) it makes sense to utilise it at the loudspeaker design stage too.)
(6) On or In wall is the best place to locate loudspeakers...In one move this eliminates the most serious room / loudspeaker interface problems...Use the room boundaries / gain to your advantage instead of fighting the room reflections.
(7) Increase Sd and maximise sensitivity....Decrease driver diaphragm movement....Full height floor to ceiling line arrays are the best way to achieve this, 70% of floor to ceiling height is almost as good.
I believe that the above offers a lot of advantages over traditional designs. Also there may well be a way to combine an open baffle bass low midrange (similar to Lynn's design) with either a line array or panel of BMR's....Not sure as I am focusing on my own designs but it's food for thought?
I am waiting on my first production run of drivers, ETA November / December...As soon as I can get them built into the cabinets I will be commissioning a full suite of independent measurements carried out by a top professional. My aim is to have objective data that is beyond question ie accurate and not "cosmetically enhanced" as some manufacturers publish.
By the way, the photo of the 4 BMR's is just to show what they look like...They were sitting on a table not installed in a baffle!!
Hope the above is of interest.
All the best
Derek.
About circumnavigating
an instrument -while playing....-False ! A cello player is big obstacle, it covers most of the instrument with the body, so what you hear from the back is different than from the front.
And what about the "horns" themselves ?
6)False!
Musical instruments dont suffer from beaming.
Hey Picowall,
I think most people will understand my point....instruments do not suffer from "beaming"....
A cello still sounds like a Cello regardless of where you stand...It does not "beam" the higher harmonics out exclusively in front of it....
(6) You are wrong. I am right.
I don't use horns.
Cheers
Derek.
About circumnavigating
False ! A cello player is big obstacle, it covers most of the instrument with the body, so what you hear from the back is different than from the front.
And what about the "horns" themselves ?
6)False!
Hey Picowall,
I think most people will understand my point....instruments do not suffer from "beaming"....
A cello still sounds like a Cello regardless of where you stand...It does not "beam" the higher harmonics out exclusively in front of it....
(6) You are wrong. I am right.
I don't use horns.
Cheers
Derek.
Derek,
1) The BMR specs don't indicate any Xmax figure (only Xlim), so impossible to determine their linear operating range. Conventional drivers exhibit controlled (and uncontrolled) bending far below Xmax or Pmax.
2) Convenient to say when you have decided to use a driver with ragged frequency response
.3) Correct, they show if the off axis response corresponds to the on axis response, if it does not, EQ can't correct the problem.
4) That's a subjective observation which I partially agree with, though I prefer both flat frequency response and good time domain performance.
5) "Perfectly acceptable" if correctable with EQ, which requires unit to unit consistency, presently not demonstrable with the BMRs.
6) Another subjective opinion I happen to agree with.
7) A full height line array has a destructive interference pattern in the near field, which extends far beyond the typical listening position in the high frequency range. You may prefer that sound (an interference pattern does not have correct time domain performance), others (like me) prefer the approach Lynn has taken with drivers and horns more closely approximating a point source.
Art
Bending mode ridge travel and Eq.
Hi Art,
Sorry but you are still not correct!
I don't want to ramble on ( applause from the crowd!) re the technical differences of the BMR as its completely OT, but suffice to say you are mistaken...If you imagine holding a flat paper cone and moving it a few mm in out in a push / pull or pistonic motion there is your cone / dome driver.
Now imagine holding the same flat paper cone and simply bending it in and out along its horizontal ( or vertical or any axis...) and note the difference....
In the first case the Vd ( volume displaced) by the push pull motion is X ( Sd times travel). Now in the second case only the "ridge" or axial line travels the peak " in / out" distance, the rest of the flat diaphragm covers less distance the closer it is relative to the surround (where your fingers are holding the cone in our imaginary example.
As you can imagine this throws out any conventional TS data re Xmax and Vd,
one reason modelling BMR's is so tricky... If you want to discuss any more on this PM me or Google around for the facts rather than assumptions based on TS data.
Back on topic as Eq is of relevance to all.
For the avoidance of doubt (your point 5 reply is ambiguous) and repeating my point 5, Eq can only correct frequency response errors when the driver has very good off axis performance ie almost perfect power response. In all other cases Eq does more harm than good. Its fine in the bass and low mids where its easy to achieve very broad off axis coverage, but it gets tougher as frequency rises. The BMR is very strong in this respect.
Cheers
Derek.
Hi Art,
Sorry but you are still not correct!
I don't want to ramble on ( applause from the crowd!) re the technical differences of the BMR as its completely OT, but suffice to say you are mistaken...If you imagine holding a flat paper cone and moving it a few mm in out in a push / pull or pistonic motion there is your cone / dome driver.
Now imagine holding the same flat paper cone and simply bending it in and out along its horizontal ( or vertical or any axis...) and note the difference....
In the first case the Vd ( volume displaced) by the push pull motion is X ( Sd times travel). Now in the second case only the "ridge" or axial line travels the peak " in / out" distance, the rest of the flat diaphragm covers less distance the closer it is relative to the surround (where your fingers are holding the cone in our imaginary example.
As you can imagine this throws out any conventional TS data re Xmax and Vd,
one reason modelling BMR's is so tricky... If you want to discuss any more on this PM me or Google around for the facts rather than assumptions based on TS data.
Back on topic as Eq is of relevance to all.
For the avoidance of doubt (your point 5 reply is ambiguous) and repeating my point 5, Eq can only correct frequency response errors when the driver has very good off axis performance ie almost perfect power response. In all other cases Eq does more harm than good. Its fine in the bass and low mids where its easy to achieve very broad off axis coverage, but it gets tougher as frequency rises. The BMR is very strong in this respect.
Cheers
Derek.
Please, go on. I'm enjoying the back-and-forth exchange; it's been fun to read, and new info to me.
As for my own speakers, it will be a twin-15 development of what Gary Dahl (and a few others) are listening to right now. Like the Ariels, they are designed for (exclusive) use with low-to-moderate power direct-heated-triode amplifiers in the 5 to 20-watt range, as well as moderate-power PP-pentode amplifiers (6L6, KT66, EL84 and EL34, etc.) in the 15 to 35-watt range. Thus, no DSP processing, since there's no power to spare (unless the horn is separately powered), direct-arrival response is flat as possible by selecting drivers and horns with flat in-band responses, and a fairly simple passive crossover.
Not that different than the design goals of the original Ariel, just 5 to 8 dB higher efficiency, and more headroom. If you don't think the Ariel is good, you won't like this one either, since the system voicing, intended matching equipment, and overall philosophy are similar. Many horn enthusiasts wouldn't consider it a horn system at all; it's just another 2-way direct-radiator + horn combination, which go all the way back to the Lansing Iconic of the Thirties.
For enthusiasts with multiple transistor amps and PC-based DSP, you have far more choices in system topology, so I'm enjoying reading about what paths you've chosen and why you made the decisions that you did. It's all good to me.
As for my own speakers, it will be a twin-15 development of what Gary Dahl (and a few others) are listening to right now. Like the Ariels, they are designed for (exclusive) use with low-to-moderate power direct-heated-triode amplifiers in the 5 to 20-watt range, as well as moderate-power PP-pentode amplifiers (6L6, KT66, EL84 and EL34, etc.) in the 15 to 35-watt range. Thus, no DSP processing, since there's no power to spare (unless the horn is separately powered), direct-arrival response is flat as possible by selecting drivers and horns with flat in-band responses, and a fairly simple passive crossover.
Not that different than the design goals of the original Ariel, just 5 to 8 dB higher efficiency, and more headroom. If you don't think the Ariel is good, you won't like this one either, since the system voicing, intended matching equipment, and overall philosophy are similar. Many horn enthusiasts wouldn't consider it a horn system at all; it's just another 2-way direct-radiator + horn combination, which go all the way back to the Lansing Iconic of the Thirties.
For enthusiasts with multiple transistor amps and PC-based DSP, you have far more choices in system topology, so I'm enjoying reading about what paths you've chosen and why you made the decisions that you did. It's all good to me.
Last edited:
Overkill. FWIW I went to a demo of the Tectonic Labs speakers in Las Vegas a few months back. It's their pro line-array system. Very interesting demo. They were really clean, even at high SPLs. Seemed very wide and even, and just didn't sound quite like other speakers. They claim very low distortion.
I tried to drag Tom Danley over to hear them, but he was so busy at the show I could never catch him. Really wanted to get his reaction.
They call them Distributed Mode Loudspeaker (DML) not BMR, same idea of course. I've built some using the little "exciters" and they were interesting, but nothing to really pursue. Great was my surprise at hearing the Tectonic panels. Of course they are very high tech and very expensive, but I could certainly see them as a home Hi-Fi speaker. Never thought I'd say that about DML.
I tried to drag Tom Danley over to hear them, but he was so busy at the show I could never catch him. Really wanted to get his reaction.
They call them Distributed Mode Loudspeaker (DML) not BMR, same idea of course. I've built some using the little "exciters" and they were interesting, but nothing to really pursue. Great was my surprise at hearing the Tectonic panels. Of course they are very high tech and very expensive, but I could certainly see them as a home Hi-Fi speaker. Never thought I'd say that about DML.
Derek,
Since Lynn likes the discussion, I'll continue it
.1) I appreciate your difficulties in modeling a BMR, but you could easily measure distortion to determine at what excursion vs. frequency the BMR goes beyond it's linear range of operation, giving an equivalent to the standard Xmax rating. Without that basic information, no way to estimate how many BMR it would take to be equivalent to a 15" driver.
2) I agree that one can only correct frequency response deviations when the off-axis response is the same, or quite similar to the on axis response. That said, there is no data I can find, or you have provided, that supports that a BMR's off axis response matches the on axis response.
EQ can be useful to correct frequency response variations (and also generally concurrently corrects phase deviation), but individual units must be identical in their frequency response deviations (both on and off axis) for the correction to work. You have not shown (demonstrated) any BMR response showing on and off axis response, though you have confirmed that their on axis response is ragged, as can be seen in the published response of various BMR drivers.
My experience in drivers showing ragged peaks and dips in response is that the raggedness is seldom the same unit to unit. If you can show (demonstrate with un-smoothed frequency response curves at say, 5 degree increments) that multiple BMR units have the same ragged response on and off axis, I would accept that the ragged response can be equalized, given EQ with enough filters.
It appears the CSS BMR85DD N4Y would require at least 8 filters, but without any off axis data, who knows how much collateral damage those filters would cause
Art
And *Weltersys* happens to agree with you, intending being it a subjectively feeling. So + 2...I'm counting...!