I am not just arguing over terminology but explaining the TECHNOLOGY behind DML and BMR.
My contribution will get the OP to think about what I just wrote because if he likes the sound of the BMR driver he can amplify it 10 fold by using DML/EXCITERS combined with BMR technology of which is just adding a surround and a spine/frame but on a much LARGER radiating SURFACE.
Like I said before BMR technology is NOTHING NEW, the only thing new is its NAME>Balanced Mode Radiator.
You shouldnt have responded in the first place let alone 2 posts after. LOL
My contribution will get the OP to think about what I just wrote because if he likes the sound of the BMR driver he can amplify it 10 fold by using DML/EXCITERS combined with BMR technology of which is just adding a surround and a spine/frame but on a much LARGER radiating SURFACE.
Like I said before BMR technology is NOTHING NEW, the only thing new is its NAME>Balanced Mode Radiator.
You shouldnt have responded in the first place let alone 2 posts after. LOL
If you prefer to call any moving coil motor assembly an exciter, you can go on and do so. But I am afraid that's not the usual term for such device in the Anglosphere, at least not the Commonwealth.
The term "exciter" used by NXT refers specifically to a transducer mounted to a lightweight panel that is to be excited by the said "exciter", hence termed "exciter".
On the other contrary, Balanced Mode Radiators (BMRs) are self-contained drivers. The rubber surround (and more importantly, mass loading on the edge of the flat honeycomb panel to "counter-balance" the mass of the moving coil) and the conventional frame/basket are exactly what makes them not exactly DMLs. They are designed to behave like DMLs in the mid-high frequency - the mass loaded edge of the panel causes the wave propagated to be reflected just like how DMLs would behave. However, in the mid/bass, the entire panel moves just like any conventional pistonic driver would. Perhaps you still haven't read the whitepaper. It's a good read.
The line array design discussed here is nothing like Dr. Katz's Podium Sound design which utilises one single light honeycomb panel with multiple "exciters", but multiple BMR drivers mounted on a solid baffle thus the reference to a previous design which utilises multiple Vifa TC9/TG9 drivers.
Putting 25 in a line array and EQ'ing it helps with the bass and loudness
Bought a MiniDSP and the bass boost does the job admirably.
EXCITERS/TRANSDUCER are the same thing just different wording. you say tomato I say tomanatto LOL
On the contrary they are exciters/transducers that utilize the conventional speaker containment techniques of a frame and a surround holding the surface material.
Not exactly DML's, but designed to behave like DML's??? Do you know how contradicting you sound right now? LMAO....Once again they are EXCITERS/TRANSDUCERS, the difference is they are utilizing different designs.
White paper??? I do not need to read this white paper to know about exciter/transducer technology. lol
Once again you sound very contradicting by saying Katz Podiums using "multiple" exciters is nothing like using "multiple" BMR drivers in a line array. SMDH. This is where you are sorely mistaken. LOL
I have never heard the Podiums but they are built somewhat similar to my DML panel designs in which both of our designs utilize some sort of surround attached to a spine on a frame.
I have used BMR drivers and they sound very, VERY similar to my DML/exciter panel designs for the mere fact that we are both using the SAME DESIGN, hence why BMR drivers ARE EXCITERS/TRANSDUCERS....I even took apart a brand new BMR driver just to confirm what I already knew. LOL
DML is like a Open Baffle speaker......BMR is like enclosed baffle speaker....BUT they both can work both ways if your design is done right.
One can buy a exciter/transducer from P.E. and turn it into a BMR driver by utilizing a frame and surrounds....while one can take a BMR driver and dismantle the surrounds and the plastic frame and turn it into a exciter/transducer as Ive done it.
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Well done there, I hope your self-proclaimed expertise will be recognised and appreciated somewhere else, but just several things here:
1. Despite the similarities, DMLs are not BMRs, not only in terms of the working principle behind but also the patent descriptions.
Give this a read, that should give you an idea why BMRs behave like DMLs in the mid-high frequency but should not be called DMLs.
And here's Naim's whitepaper on BMRs.
All moving coil speakers have a voice coil/motor design, that doesn't make them DMLs or BMRs by default. It's like saying cats and dogs belong to the same species because they walk on all fours and are covered by fur.
2. I'll be very surprised to learn there's no difference between one single large membrane with multiple motors and multiple, smaller drivers - the Fs will definitely be different, and the dispersion behaviour will probably be different as well. You're basically suggesting bushmeister to build a DML rather than BMRs. Doable but not the same thing, the working principle is totally different.
1. Despite the similarities, DMLs are not BMRs, not only in terms of the working principle behind but also the patent descriptions.
Give this a read, that should give you an idea why BMRs behave like DMLs in the mid-high frequency but should not be called DMLs.
And here's Naim's whitepaper on BMRs.
All moving coil speakers have a voice coil/motor design, that doesn't make them DMLs or BMRs by default. It's like saying cats and dogs belong to the same species because they walk on all fours and are covered by fur.
2. I'll be very surprised to learn there's no difference between one single large membrane with multiple motors and multiple, smaller drivers - the Fs will definitely be different, and the dispersion behaviour will probably be different as well. You're basically suggesting bushmeister to build a DML rather than BMRs. Doable but not the same thing, the working principle is totally different.
Wow guys! So many opinions and thoughts!!
I like it!
To be fair the BMR thing is interesting. Fluid and wesayso you have good points about going open baffle. It will kinda negate the whole point of having tweeter like dispersion and something I have thought back and forth on...I can't help thinking that the lateral nulls will be better formed with such high dispersion full range drivers...good points on the difficulty in making a stiff open baffle at over 2 meters height too....hmm
If I went sealed I would probably go tubular or D section.....
Fluid, valuable insight into the tc9 and the dispersion of the BMR - I agree perhaps less even.....but how important is that when so high? And good thoughts on driver summation....but is there evidence for this?
The largest question is still for me: will the very good high range dispersion increase lobing issues or improve them?? Is there evidence to back up that beaming improves the situation?
For instance we often see in multi-way line array speakers line arrays of tweeters. Even the small faceplate versions will have a similar or larger c-c distance than these tiny 2" BMR drivers....and similar polars......
Thanks again for all the thoughts!
I like it!
To be fair the BMR thing is interesting. Fluid and wesayso you have good points about going open baffle. It will kinda negate the whole point of having tweeter like dispersion and something I have thought back and forth on...I can't help thinking that the lateral nulls will be better formed with such high dispersion full range drivers...good points on the difficulty in making a stiff open baffle at over 2 meters height too....hmm
If I went sealed I would probably go tubular or D section.....
Fluid, valuable insight into the tc9 and the dispersion of the BMR - I agree perhaps less even.....but how important is that when so high? And good thoughts on driver summation....but is there evidence for this?
The largest question is still for me: will the very good high range dispersion increase lobing issues or improve them?? Is there evidence to back up that beaming improves the situation?
For instance we often see in multi-way line array speakers line arrays of tweeters. Even the small faceplate versions will have a similar or larger c-c distance than these tiny 2" BMR drivers....and similar polars......
Thanks again for all the thoughts!
Look who is talking about one being a self proclaimed expert.
as IDGAF if its recognized or appreciated. ...sounds like what people are calling SJW. LOL1. DML's and BMR's are very similar because like I said in my FIRST post they all use EXCITERS aka transducers....the ONLY DIFFERENCE is in the DESIGN and even at that a DML panel can become a BMR design if one so chooses and vice versa....you know exactly what I am talking about you just refuse to accept it as the main principle of this technology is EXCITERS...patented descriptions is just a different design of using exciters, which by the way like I said before its NOTHING NEW as it has already been done even way before the BMR patented ever existed. LOL....that analogy of cats and dogs is does not fit the description and is every inaccurate. Instead it should be that all dogs come from the same species covered with fur and walk on four legs but there are many DIFFERENT (designs) BREEDS of dogs.
2. I never said they be exactly the same as different designs will produce different results....The main goal of using multiple small drivers is to basically try to create one coherent big driver by the smaller drivers working together in unison....DML instead of using so many small drivers can use one big panel as the driver....its not really about how many drivers but the total amount of the surface area of the drivers.
DMLS and BMRs sound and behave very very similar (even you admitted it lol) especially when utilizing the same design as exciter technology has a very unique sound and one will either like or dislike this unique sound. That is why I suggested that if he LIKES the sound of the BMRs then there is another option....They might not be exactly the same but the similarities of them having that same UNIQUE exciter technology and the principle is not totally different as it can be very very similar depending on ones design.....Its just weird as you make it sound like I am forcing him to follow my advice by discouraging me as if what I am saying is all wrong and or that my opinion is invalid. LMAOROTF
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You're entitled to your own opinion, if you think DML and BMR are the same because they utilise "exciter" (read: motor assembly), then go ahead. Mind you, all moving coil divers utilise a similar motor assembly comprising of a spider, voice coil, magnet, pole piece and pole plate. The motor design on the BMR enables long excursion and that on the DML exciter does not, if you haven't noticed it.
And utilising multiple drivers have other effects like combing effect, affects the directivity, thus more than just increasing the radiating surface area. Get your facts right.
I'll stop replying you from this point onwards because the original discussion is about using BMRs for line array, not building DMLs or working principle of DMLs (which you're highly advised to read the original papers before coming up with such a conclusion)
And utilising multiple drivers have other effects like combing effect, affects the directivity, thus more than just increasing the radiating surface area. Get your facts right.
I'll stop replying you from this point onwards because the original discussion is about using BMRs for line array, not building DMLs or working principle of DMLs (which you're highly advised to read the original papers before coming up with such a conclusion)
You are also entitled to your opinion but the FACT remains they both utilize a EXCITER/transducer which is what I said in my FIRST post....Another misconception on your part is that you believe the BMR's to have more excursion then the DML exciters which is not true.
Once again I didnt say multiple drivers dont have other effects like combing, directivity etc...you are just putting word into my mouth to suit your needs talk about someone getting there facts right. LOL
You can do what ever you want from any point on but its ironic only after so many posts you finally decided to concentrate on the original discussion at hand. LOL
Original papers? You mean Naim's or Cambridges theory on BMR? LOL....They are just duplicating NXT's BMR.....like I've said many times before the term Balanced Mode Radiator (BMR) existed way before NXT started making there NXT panels in the 90's. The only thing that is new is the NAME BMR but that technology was created long before the name BMR ever existed. LOL
Once again I didnt say multiple drivers dont have other effects like combing, directivity etc...you are just putting word into my mouth to suit your needs talk about someone getting there facts right. LOL
You can do what ever you want from any point on but its ironic only after so many posts you finally decided to concentrate on the original discussion at hand. LOL
Original papers? You mean Naim's or Cambridges theory on BMR? LOL....They are just duplicating NXT's BMR.....like I've said many times before the term Balanced Mode Radiator (BMR) existed way before NXT started making there NXT panels in the 90's. The only thing that is new is the NAME BMR but that technology was created long before the name BMR ever existed. LOL
Sorry mate didn't intend to hijack the thread. Here's my 2p worth:
The wide dispersion shouldn't worsen the lobing/combing effect per se, but a line array using the said BMR will probably have reduced dispersion compared with say using one single BMR. With close spacing between drivers, it will probably be fine up to 8kHz, then you may need a bit of equalisation to compensate like in the TC9/TG9 array. I remember there's a PhD paper on near field line array in which inter-driver spacing and lobing is discussed, probably by Griffin.
The lateral nulling shouldn't be too different from other drivers since the front/back output of these drivers is asymmetrical, there shouldn't be too much treble output from the back. Haven't done any measurements though.
I can't see any reason that it would make it worse, according to Linkwitz matching the baffle width to the driver size is an improvement and is why the LX521 baffle is shaped the way it is. When using one driver to cover a large range you can't do that and having a large baffle to reduce dipole rolloff to a lower frequency could be counterproductive higher up the frequency range.
I thought about using a pipe. Pain to get a flat baffle in the front of it to mount the drivers. D section has a flat part which will make your life easier. I went simple box construction and I don't regret that decision. There is a lot of work in a line array.
A driver that has even off axis performance will produce specular reflections that have a similar tonality to the direct sound. They are less distracting than reflections that are very different. Rolling off in the highs is normal, up and down response like the power response irregularities that are common in cone a dome speakers are quite audible. If you intend to absorb or change the directivity to limit them then that might not be so much of an issue. What I see in my measurements is the offaxis sound dominating, so I want that to be as smooth and even as it can be. Any EQ will then work over a larger area.
On driver summation if you mean the combing based on CTC then Jim Griffins paper sets it out and many measurements mine included back it up. For my size driver's it starts at 4K but is not really much in evidence till beyond 10K at my listening distance.
Comb filtering is the red herring problem of line arrays. Important to consider and minimize but not as damaging as it seems in practice.
The vertical directivity in general comes from the length, floor and ceiling reflections play a part in extending the line acoustically and in theory but in practice the length is the dominant factor. The single driver response sets the horizontal directivity. I can't speak as to whether very wide is better than wide enough. I think it might come back to the imaging vs spaciousness debate as to which you would want.
Yes not the poison I picked, I wanted to avoid the crossover. The CBT arrangement of more small tweeters than woofers works to overcome that. The price goes sky high and the quality of the drivers often suffers to keep it more reasonable. If money is no object then I can see it as a workable solution.
Hi fluid, actually I am not talking about horizontal or vertical dispersion of the full array or combing in relation to driver size, or indeed combing in relation to c-c distance. All these things are all ready well described and easy to understand. But thanks for your input in these points.
The question I am clearly not asking very well is whether the inherently different dispersion of the BMR drivers to all normal cone and dome drivers (I.e. the measurements I linked to in my first post which demonstrate a 2 inch BMR with the dispersion characteristics of a sub 1" tweeter) will have bearing on the combing of the array.
I am aware they will have near 180 lateral spread, and vertical will be defined by array length, but given most 2" cone drivers with the same c-c distance will have worse high freq beaming, does this affect the formation of combing positively or negatively?
I just wonder if no-one really knows? If so my best best will be to buy 10 to find out....
You see in my head, if a driver starts beaming at the same freq as the c-c combing freq, well wouldn't this be a way of mitigating the combing?!?
The question I am clearly not asking very well is whether the inherently different dispersion of the BMR drivers to all normal cone and dome drivers (I.e. the measurements I linked to in my first post which demonstrate a 2 inch BMR with the dispersion characteristics of a sub 1" tweeter) will have bearing on the combing of the array.
I am aware they will have near 180 lateral spread, and vertical will be defined by array length, but given most 2" cone drivers with the same c-c distance will have worse high freq beaming, does this affect the formation of combing positively or negatively?
I just wonder if no-one really knows? If so my best best will be to buy 10 to find out....
You see in my head, if a driver starts beaming at the same freq as the c-c combing freq, well wouldn't this be a way of mitigating the combing?!?
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The wider directivity at high frequencies makes the driver behave like a small dome tweeter. The summed response of many sources will be as if its an array of small domes spaced at the CTC of the actual driver.
As far as difference between such a driver and a narrow directivity coned driver is concerned, probably it would not matter in actual listening since in either case EQ would be used to level out the differences. Combing is already proven to be a non issue, in actual listening, especially when there are many sources and greater listening distance. They may measure different though in the combing region.
OK, that is a helpful answer = probably doesn't matter in real life!
OK, in which case fluid makes a really strong case for the tc9/tg9...
The BMR seems less attractive to me, if it's strongest selling point (dispersion) it not a useful feature in an array.
So onto further thoughts....I really love the sound of my horn loaded SB65.....
OK, in which case fluid makes a really strong case for the tc9/tg9...
The BMR seems less attractive to me, if it's strongest selling point (dispersion) it not a useful feature in an array.
So onto further thoughts....I really love the sound of my horn loaded SB65.....
If you're implying the beaming of the full range drivers would act as a sort of frequency dependent shading it probably would, if they were perfect enough like a small tweeter in a waveguide can be. But (even small) full range drivers are not perfect enough on the top end.
The combing can be largely reduced, close to being eliminated completely at a preferred listening distance. Much like a focussed array, though with a straight array it actually works over a wider area.
A CBT array mimics a point source originating from the center of the arc. So it acts as if the wave front comes from that point.
The focussed array will only relieve or prevent combing in the small focussed spot it was designed for.
In my humble (or maby not so humble) opinion, an EQ-ed straight array can act similar to the CBT at a chosen, more or less fixed listening distance(*). It will still sound good and even at other distances but tiny differences can be percieved. To get the most out of stereo you should sit in the sweet spot (which is true for all stereo speakers). However even off axis it still sounds very good as noted by a few independent listeners in the reviews I got. The sweet spot is magical though. Especially after the other tricks I used to counter some of Stereo's inherrent flaws.
The measurements I have seen on CBT arrays up till now did not convince me they are superior to a FIR corrected floor to ceiling array. But you'd have to believe in measurements to see that as important
.I did all I was allowed to do (determined by my better half) to make it work with the room. Which is easy, because of how arrays work.
(*) = the fixed distance is way less strict than this wording may imply. It covers a complete couch at 3m without sounding odd at any other point in the room. This is very different from more traditional speakers which change even when standing up, let alone moving trough the room. Any change is very gradual.
The absence of early reflections make it seem like an optimised near field listening setup but with a way more life like experience in size, dynamics and even feel.
Maybe I should put in the disclaimer of an array that is used as full range, though I'm sure with some care subs should work well to. The coherent sound is often mentioned though by listeners in my room.
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