What do you find so subpar about this tweeter ? - the rising FR a few dB at 1kHz (so BTW in the xo region already) ? Other than that I'd think it is a rather decent performer and the mechanical design scores pretty strong. What alternative could you suggest that would not force the mids to be placed further apart ?
I dont think the reference was to the particular tweeter you have chosen - rather, some typical tweeter stuck on a post in the middle of a larger driver's cone to make a 'co-axial' arrangement.
You get them coincident allright but downside to this arrangement is that the response narrows with the few octaves the woofers interact but when the tweeter is crossed over the response gets full wide again. Whether this matters or not I don't know but it will show up in power response boost on the tweeter and would possibly make getting the system balance hard. In other words the system might sound bit off no matter how you tune the balance. Another issue might be the tweeter is hard pressed for the crossover and makes the system SPL limited, or just move crossover up and chase the tail 🙂
Honestly, from just reasoning things I don't know how MTM system would ever work but hey they still do in practice, at least to some extent 😀 Lets lay some more thoughts on it: You could use a long ribbon instead of a dome tweeter to narrow the tweeters vertical response as well for example, but hey this again pushes the woofer c-c longer than the ribbon can support the pattern so. Its just physically impossible, unless the crossover is very low in frequency like in planet10 example earlier, few hundreds of hertz between full range driver and woofers to get slack on the c-c spacing. But this is again SPL limited system with wide response above the crossover. Basically MTM feels like a poor variation from coaxial woofer+tweeter. On the other hand one could have wave guide on the MTM tweeter and manipulate its directivity between vertical and horizontal axis so that DI and power stays constant across the crossover, basically woofers being narrower than tweeter on vertical axis and wider than tweeter on horizontal axis but again this might have some issues even though the graphs would now be nice and predict good sound.
Like said earlier any system have their ups and downs and since you are interested in making coincident speaker you can do the MTM as planned and see how you like it. If it wasn't life long companion then it is time for something else 🙂 I would add more woofers so WMTMW or even more, to keep vertical response narrow through the mid range. In addition to being point source it would reduce influence of vertical early reflections, which is the sole point of such driver arrangement, difference to all the other possible point source systems. If you check out what ceiling and floor reflections do to response at listening position the worst things happen between few hundred hertz to few kilohertz, keep this area narrow vertically if at all possible for maximum advantage.
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That's exactlyu what was originally behind the title thread question - is it really a poor variation when the MTM has the same physical size as the coaxial woofer ? I have not seen so far a physics-backed explanation why it should be so. It is typically about the overall size which applies similarly to coax nad MTM., not ?
yeah, MTM just can't get the tweeter close enough not to have "issues" with off-axis response while a tweeter middle of a woofer performs much better in this regard and this is the trade-off. Or the other way around if one used big woofer coaxial instead of two smaller ones stacked vertically in MTM both would have very similar polar pattern on vertical axis as you suspect. In both cases the tweeter needs to be crossed over at low frequency where the dispersion of both the tweeter and woofer(s) is about the same, or the tweeters response would need to be made narrower for some higher crossover point, otherwise the dispersion suffers around crossover quite similarly in both cases. Think ~5" coaxial speaker, can you make a MTM for that space, total ~5"? Three ~1" transducers without significant structure could make into it perhaps but it would have much less cone area than a 5" woofer and would not play as low frequency, not too much lower than just a single tweeter, or 5" long ribbon tweeter for example. The additional structure (frames) of multiple transducers will make MTM poorer performer here, taking up space. Hence main benefit and about only reason to go MTM configuration is the narrow vertical pattern, in my opinion.
Thinking point source with good off-axis response: How low 1" tweeters can cross comfortably, perhaps 2kHz? One would need woofer system (or woofer size) that does not beam too much here to meet dispersion of the 1" tweeter so basically ~<6" coaxials are fine, or MTM system that spans max ~6" for same performance. If it gets wider or bigger than this then the pattern suffers. One could use compression driver to get crossover lower, perhaps to 1kHz for 8" or 10" woofer or even lower with bigger compression driver but then the top octave starts to suffer. Its just matter of picking the poison 🙂 MTM inevitably narrows vertical response, make use of it.
Some more thoughts on it:
A tweeter middle of a woofer, and the woofer, would have similar pattern (and quite wide) both vertical and horizontal axis as they are axisymmetric. If you wanted narrower dispersion the tweeter would need to be on a separate waveguide to narrow its response, and this kind of coaxials also exists but then there are some other issues, mainly either the tweeter waveguide causes diffraction/reflections on the woofer response. Or if the waveguide is small to not affect woofers output their radiation patterns don't meet making lumpy power response as the woofer would narrow (being bigger than the tweeter waveguide) on a lower frequency. And it is hard to get narrow vertical dispersion while having wide horizontal dispersion with a waveguide, much easier with array, by acoustic interference like in MTM.
Whats behind all this is just wavelength, speed of sound in the air. Constructive and destructive interference happens when same sound (coherence) is emitted at different locations. This is true for separate transducers like two mid woofers in MTM speaker or just a tweeter and mid on a MT speaker at around crossover frequency, but also for a single transducer. One can imagine sound to emerge from opposite sides of single woofer cone, pick two points in your imagination, then move off-axis in relation and path length from both of these points are now different to your ear and interfence happens. When the distance from two sources is significant in comparison to wavelength there is both destructive and constructive interference that looks like a comb filter in frequency response plot. When path length difference is less than 1/4 wavelength then there is only constructive interference. This same phenomenon is behind the idea that having transducers within 1/4wl makes a point source as well as driver beaming or lobing. Driver beams when wavelength is shorter than the driver diameter and increasingly so. At some high frequency there is constructive interference mostly directly on-axis while anywhere off-axis averages out.
Basically the size of transducers, be it a coaxial or MTM config and their position in relation to each other, or just single fullrange driver, makes system acoustic output what it is. And then the construct can affects some as for example edge diffraction makes yet another sound source.
Thinking point source with good off-axis response: How low 1" tweeters can cross comfortably, perhaps 2kHz? One would need woofer system (or woofer size) that does not beam too much here to meet dispersion of the 1" tweeter so basically ~<6" coaxials are fine, or MTM system that spans max ~6" for same performance. If it gets wider or bigger than this then the pattern suffers. One could use compression driver to get crossover lower, perhaps to 1kHz for 8" or 10" woofer or even lower with bigger compression driver but then the top octave starts to suffer. Its just matter of picking the poison 🙂 MTM inevitably narrows vertical response, make use of it.
Some more thoughts on it:
A tweeter middle of a woofer, and the woofer, would have similar pattern (and quite wide) both vertical and horizontal axis as they are axisymmetric. If you wanted narrower dispersion the tweeter would need to be on a separate waveguide to narrow its response, and this kind of coaxials also exists but then there are some other issues, mainly either the tweeter waveguide causes diffraction/reflections on the woofer response. Or if the waveguide is small to not affect woofers output their radiation patterns don't meet making lumpy power response as the woofer would narrow (being bigger than the tweeter waveguide) on a lower frequency. And it is hard to get narrow vertical dispersion while having wide horizontal dispersion with a waveguide, much easier with array, by acoustic interference like in MTM.
Whats behind all this is just wavelength, speed of sound in the air. Constructive and destructive interference happens when same sound (coherence) is emitted at different locations. This is true for separate transducers like two mid woofers in MTM speaker or just a tweeter and mid on a MT speaker at around crossover frequency, but also for a single transducer. One can imagine sound to emerge from opposite sides of single woofer cone, pick two points in your imagination, then move off-axis in relation and path length from both of these points are now different to your ear and interfence happens. When the distance from two sources is significant in comparison to wavelength there is both destructive and constructive interference that looks like a comb filter in frequency response plot. When path length difference is less than 1/4 wavelength then there is only constructive interference. This same phenomenon is behind the idea that having transducers within 1/4wl makes a point source as well as driver beaming or lobing. Driver beams when wavelength is shorter than the driver diameter and increasingly so. At some high frequency there is constructive interference mostly directly on-axis while anywhere off-axis averages out.
Basically the size of transducers, be it a coaxial or MTM config and their position in relation to each other, or just single fullrange driver, makes system acoustic output what it is. And then the construct can affects some as for example edge diffraction makes yet another sound source.
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The edge diffraction is what has been my interest for some time now and new thoughts emerge just now with this point source discussion 😀 Can you make the (whole baffle) edge diffraction also be part of the point source? Few things can make it, either the sound cannot be let to the edge when it is further away than 1/4wl (or is it 1/8wl) or the edge needs to be much further where it cannot be distinquished from rest of the environment, the room, or just make the edge disappear by roundovers.
Small coaxial on a big enough sphere would make nice point source. Or if narrow directivity is needed then multiple entry horn would do, but even that has some diffraction but perhaps within 1/4 wl though so not that much of an issue I guess. Big enough mouth to make it diffract very low in frequency or just use big roundover there as well.
Small coaxial on a big enough sphere would make nice point source. Or if narrow directivity is needed then multiple entry horn would do, but even that has some diffraction but perhaps within 1/4 wl though so not that much of an issue I guess. Big enough mouth to make it diffract very low in frequency or just use big roundover there as well.
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It’s what we actually hear that matters most…..and that depends on the speaker, the distance to the speaker and the room. While an MTM will produce a lobe, the farther your listening position, the less intrusive it becomes to the overall performance as the waves couple or sum……it’s the REALITY of what we perceive vs the measurements and simulations that show destructive wavefronts chopping up the sound…….your ears don’t have that resolution so don’t buy into the BS…..evolution has taken care of most of this by designing an amazing micro lens……your outer ear……a much more functional device than a microphone coil.
As to an MTM…..well……lets examine the core design goal…..greater power handling and lower bass extension by employing two woofers BUT maintaining a stand mounted design…..and THAT is the compromise. The bonus of the MTM is the reduced floor and ceiling bounce of high frequencies by virtue of cancellations……it BEHAVES like a near perfect point source directly on the vertical axis…..and I mean that literally…..move just 2-3 degrees off and the null is there BUT of your 8 feet aware, it’s mostly summed so unless your an audiophool who spends hours critically searching for flaws, you’ll likely never ever perceive it. A MUCH BETTER option would be an MTMW, WMTMW or MTMWW where smaller drivers can preserve the 1/4 wavelength yet preserve the higher power handling. Personally, if system size had little or no constraint, I have found the WWMTMWW configuration to be the most perfect system with current driver technology hand down.
Now there is one more option while meeting the small form factor stand mounted design and that would be an MTM with dual opposed side firing woofers. In this design, the MTM would have a few more limitations dictated by the side firing woofers which must be crossed low and with 1st order low pass and high pass for the M drivers. Because of this, the M drivers will either need to be more mid woofers than compact mid only……..a low TM crossover point will be needed to remain at the 1/4 wavelength so we’re talking a robust dome tweeter of a premium that can play to 1.5khz and yet still handle some power and low HD.
But at the end of the day, place any or all speakers in a bad room at a poor listening distance and all of the above just falls apart as the room contributes more than the speaker so take what I’ve said with a grain of salt and a pinch of audiophile dust……..I’ve had the pleasure of listening to a Dolby ATMOS 5.1.4 system with consumer entry level speakers in proper positioning in a well treated room with immersive mastered content and…..well…..let’s just say the worlds BEST stereo configuration won’t hold up.……unless nostalgia is your thing, stereo is finished….and long overdue IMO.
This all comes from a mix/mastering engineer mind you, who has worked in rooms where the acoustic room treatments are 5x the cost of the speakers……some of the best recordings you’ve ever heard were made with $400 Yamaha NS10’s in a $5000 room. Choose you’re opponent wisely.
As to an MTM…..well……lets examine the core design goal…..greater power handling and lower bass extension by employing two woofers BUT maintaining a stand mounted design…..and THAT is the compromise. The bonus of the MTM is the reduced floor and ceiling bounce of high frequencies by virtue of cancellations……it BEHAVES like a near perfect point source directly on the vertical axis…..and I mean that literally…..move just 2-3 degrees off and the null is there BUT of your 8 feet aware, it’s mostly summed so unless your an audiophool who spends hours critically searching for flaws, you’ll likely never ever perceive it. A MUCH BETTER option would be an MTMW, WMTMW or MTMWW where smaller drivers can preserve the 1/4 wavelength yet preserve the higher power handling. Personally, if system size had little or no constraint, I have found the WWMTMWW configuration to be the most perfect system with current driver technology hand down.
Now there is one more option while meeting the small form factor stand mounted design and that would be an MTM with dual opposed side firing woofers. In this design, the MTM would have a few more limitations dictated by the side firing woofers which must be crossed low and with 1st order low pass and high pass for the M drivers. Because of this, the M drivers will either need to be more mid woofers than compact mid only……..a low TM crossover point will be needed to remain at the 1/4 wavelength so we’re talking a robust dome tweeter of a premium that can play to 1.5khz and yet still handle some power and low HD.
But at the end of the day, place any or all speakers in a bad room at a poor listening distance and all of the above just falls apart as the room contributes more than the speaker so take what I’ve said with a grain of salt and a pinch of audiophile dust……..I’ve had the pleasure of listening to a Dolby ATMOS 5.1.4 system with consumer entry level speakers in proper positioning in a well treated room with immersive mastered content and…..well…..let’s just say the worlds BEST stereo configuration won’t hold up.……unless nostalgia is your thing, stereo is finished….and long overdue IMO.
This all comes from a mix/mastering engineer mind you, who has worked in rooms where the acoustic room treatments are 5x the cost of the speakers……some of the best recordings you’ve ever heard were made with $400 Yamaha NS10’s in a $5000 room. Choose you’re opponent wisely.
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Yeah perhaps minimizing vertical early reflections is king for perceived sound quality and for that MTM, or any array system, is more effective than waveguides if considering the horizontal dispersion needs to be wide. A waveguide or horn could also be made narrow vertical dispersion but also the horizontal dispersion would be narrowish. One could array this kind of devices horizontally to widen the response or what ever, many ways.
There are some conceptual errors on your post but that doesn't change the impression you've clearly had that narrow vertical dispersion system rocks. Its not highs that are narrow on MTM, its the mids, below tweeter crossover unless the tweeter is also "long" or in a waveguide. And to keep mids narrow for the important midrange bandwidth the system needs to be quite tall, WMTMW at least. This is easy to see on simulators or calculators and your observations suggest it would sound better the lower in frequency we control. One doesn't have to, its just that if all advantages need to be reaped then make it as tall as possible, from floor to ceiling, find tall chair to get ears midway to hit the beam 😉
The floor and ceiling first reflections are in a low angle even when listening quite close and the further one moves the listening position the lower the angles become and pretty much every other system would make more sound towards the first specular reflection points than MTM / array. Also MTM "beam" or "lobe" would get wider with distance for more comfortable sweetspot so yeah perhaps they are more effective on what they do with increased distance.
It is another matter how hearing system interprets all of it. Perhaps if the sound towards these early reflections is exactly the same as direct sound then it wouldn't matter much to have too much attenuation. Perhaps there is critical bandwidth for hearing system, say some kilohertz, so that already "short" MTM is enough to make difference. This is what has been subject of discussion for some time now. With simulators its not too hard to optimize the first reflections and have them be the very similar as direct sound even with the MT variety of speakers.
For the OP and to the context of point-source speaker MTM is not as good as coaxial as "point-source", further from ideal, but if narrow vertical dispersion is wanted property then MTM or variation is good way to do as its also kind of point-source.
There are some conceptual errors on your post but that doesn't change the impression you've clearly had that narrow vertical dispersion system rocks. Its not highs that are narrow on MTM, its the mids, below tweeter crossover unless the tweeter is also "long" or in a waveguide. And to keep mids narrow for the important midrange bandwidth the system needs to be quite tall, WMTMW at least. This is easy to see on simulators or calculators and your observations suggest it would sound better the lower in frequency we control. One doesn't have to, its just that if all advantages need to be reaped then make it as tall as possible, from floor to ceiling, find tall chair to get ears midway to hit the beam 😉
The floor and ceiling first reflections are in a low angle even when listening quite close and the further one moves the listening position the lower the angles become and pretty much every other system would make more sound towards the first specular reflection points than MTM / array. Also MTM "beam" or "lobe" would get wider with distance for more comfortable sweetspot so yeah perhaps they are more effective on what they do with increased distance.
It is another matter how hearing system interprets all of it. Perhaps if the sound towards these early reflections is exactly the same as direct sound then it wouldn't matter much to have too much attenuation. Perhaps there is critical bandwidth for hearing system, say some kilohertz, so that already "short" MTM is enough to make difference. This is what has been subject of discussion for some time now. With simulators its not too hard to optimize the first reflections and have them be the very similar as direct sound even with the MT variety of speakers.
For the OP and to the context of point-source speaker MTM is not as good as coaxial as "point-source", further from ideal, but if narrow vertical dispersion is wanted property then MTM or variation is good way to do as its also kind of point-source.
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I wouldn't state that an MTM must have narrow directivity or suffer from lobes. Again, the issue is how many wavelengths at crossover that your elements are spaced. Certainly, if you put a couple of 6" units around a wide flange tweeter and crossover at 5kHz then you are going to have some lobing and narrowed directivity. On the other hand, I have had good luck with smaller mids and tweeters with compact magnet structures. My picture on the left shows an MTM designed for the Snell XA Reference. The units were tightly packed and the CD flare around the tweeter gave it extra low end output for a lower crossover point. The other XA units used a special Boston Acoustics mid that we had made, with a diameter of about 2 1/2".
I have also done 3 tweeter arrays with the outer units rolled off, that had good polar performance (McIntosh THX models).
The key is aiming for moderate directivity and getting your central cluster tight and the top-most crossover point reasonably low. The benefit is guaranteed vertical symmetry and nearly constant directivity. In the end, I am not so much concerned with whether there are lobes or not, as wanting to get the most uniform response possible within a useful listening window.
I have also done 3 tweeter arrays with the outer units rolled off, that had good polar performance (McIntosh THX models).
The key is aiming for moderate directivity and getting your central cluster tight and the top-most crossover point reasonably low. The benefit is guaranteed vertical symmetry and nearly constant directivity. In the end, I am not so much concerned with whether there are lobes or not, as wanting to get the most uniform response possible within a useful listening window.
Just a few words what the main advantages of MTM for me are. First is being relatively close to coax as I believe precise acoustic centers alignment is critically important for sound quality and it works generally worse in a non-symmetrical setup. It is also annoying that there is no single place to properly measure the speaker and individual drivers - think active digital xovers that should be gradually be more and more with us. And then one more step - linear phase xovers should be also much better executed symmetrically.
Also having two 3" drivers (especailly fullrange) instead of a single 5" or 6" is a big benefit in terms of the other critical sound quality - driver IR speed and related transients fidelity - the essence of music. And the last one is simply limited supply of coax drivers coupled likely with the technology difficulties in making them which simply makes a similar MTM more economical and easier to optimize.
Many of the issues speaker builders assign high priority to are rather low on my list, I am not worried about FR irregularities (unless really broad range) as ear is simply not good at spotting them while I pay much more attention to the timing aspects where ear is evolutionarily hyper-sensitive (actually that's the main rationale for high res material, not the frequencies perspective). I am also not a big fan of looking too much at power/distortion issues like when talking about crossing the tweeter too low. In order for this to become a real problem you need to listen real loud and that's not what I like or practice often. I am not a manufacturer so I can afford this compromise and it makes lots of things easier 🙂
Also having two 3" drivers (especailly fullrange) instead of a single 5" or 6" is a big benefit in terms of the other critical sound quality - driver IR speed and related transients fidelity - the essence of music. And the last one is simply limited supply of coax drivers coupled likely with the technology difficulties in making them which simply makes a similar MTM more economical and easier to optimize.
Many of the issues speaker builders assign high priority to are rather low on my list, I am not worried about FR irregularities (unless really broad range) as ear is simply not good at spotting them while I pay much more attention to the timing aspects where ear is evolutionarily hyper-sensitive (actually that's the main rationale for high res material, not the frequencies perspective). I am also not a big fan of looking too much at power/distortion issues like when talking about crossing the tweeter too low. In order for this to become a real problem you need to listen real loud and that's not what I like or practice often. I am not a manufacturer so I can afford this compromise and it makes lots of things easier 🙂
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I just use the 3” FR as a midTweeter, real easy to XO low enuff to be a point source with one or more woofers.
If you need 2 series wire and shunt one with a big cap.
The best of these 3” will perform better up high than any small bezel ¾” tweeters. I have not sampled too many, but i have paid attention to them.
dave
I would probably agree that the mid/tweeter coupling including crossover is extremely difficult to execute well. Coax is one component here. And I also agree, it is quite tempting not to have this xover and go for a small fullrange. For me it is a pretty safe and easy path to get good quality, much above the average but not having a tweeter is a glass ceiling for top quality,. It just cannot be fast enough where it is needed 🙂
Just looking at what good quality coax drivers offer is available is not encouraging, just a few Seas-es come to mind.
I have tried out the most promising one and I have not been too happy. I like KEF-s quite a lot but they are not available in the open market.
BTW, mastering engineering community voice would be also much interesting to hear on these non-mainstream approach to audio design priorities in previous posts 🙂
I have tried out the most promising one and I have not been too happy. I like KEF-s quite a lot but they are not available in the open market.
BTW, mastering engineering community voice would be also much interesting to hear on these non-mainstream approach to audio design priorities in previous posts 🙂
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I'd like to test this design in practice soon but have a problem with finding good tweeter, the Vifa OX20SC02 I have selected has poor availability in Europe, can you suggest alternatives ? The priority is possibly minimalistic enclosure, 3/4" preferably but 1" not excluded, >=87dB (1W/m) effficiency and reaching decently low. Not necessarily top shelf, good price/quality tips would be most appreciated.
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MTM are generally assumed to be like two woofers 5"-6" flanking a tweeter, even if not stated so. Your thought of like a couple 3" is atypical, and if the crossover is kept low would work better than usual (except can't handle much midbass power so now you need woofers = WMTMW. Coaxials are inherently radially symmetrical, unlike MTM. But the cone may or may not be a nice load on the tweeter, the "connection" from tweeter diaphragm to woofer cone likely is not truly smooth, and the horn formed by the woofer moves with woofer excursion, modulating the response. Practically speaking, I've noted all the SEAS coaxials seem to have really ragged responses. I can tell you firsthand that every automotive bridge-style coax I ever measured had problems caused by reflection from the cone behind the tweeter and from the bridge, and not easy to fix in the crossover.
Just a few Seas have 'promising' coax? Which one please? I've never seen any Seas coax used in a product used in profield ( studio).
Kef drivers are availlable as spare parts if you search for them enough. Where are you located?
What do you want mastering engineer to have authority on a purely subjective subject ( most mastering engineer doesn't have a clue of the technical tradeoff/compromise that have to be done in loudspeakers design, even if some are able to point the 'issues' each one potentially have by ears)? I mean i've been in enough mastering rooms to know there is as much point of view as there is engineer.
This doesn't exclude either coax or verticaly aligned array to be used by them... Let's take some 'famous' names: Last time i've looked at B.Katz's gear he used a Dynaudio vertically aligned ( wmtmw) in one room, Genelec coax the another room.
Simon Davey from 'The Exchange' ( as well as the other engineer working in the place) use(d) Tannoy System15 Dmt2.
There was at least one 'typical' T.Hidley's Non Environment room used in Nashville for mastering, using his 'standard' offer for loudspeakers ( Kinoshita Rm7, 2x15"+2" MTM).
Manley based their mastering monitors offer on a 12" Tannoy...
You won't find answers from this imho, or at least not the one you seems to expect.
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In real life, the room will play a much larger role in the perceived sound than any amount of agonising over driver spacing will ever achieve...
I suspect that coaxials will never become popular on the DIY scene due to the limited choice and the apparent simplicity of simply buying a driver and building a box for it - no agonising required!
I suspect that coaxials will never become popular on the DIY scene due to the limited choice and the apparent simplicity of simply buying a driver and building a box for it - no agonising required!
If it was so simple with coax that would be great! In practice it is not as most of them have an offset between drivers in the array and this brings it's own set of specificities in xover design. Latest Kef, Tannoy and some B&C drivers doesn't have these issue thought. I think Fyere drivers belong to them too but i'm not sure.
And i think most people wants two way from them which is an error. They beg for 3ways and being relief from bass duties. At least it was the case for the ones i own/played with.
I don't think there is limited offer on coax. There is limited offer on 'hifi' targeted drivers though... but i'll never get the difference between 'targeted' offer. A driver is a driver, it does what you expect it to do, or not.
About room, well +1 with Mr Klinky and Mayhem13.
@pawelp if you are located in EU then there is a source for Kef spare parts if you are interested in playing with them ( and considered you have a tweet+mid+waveguide i don't find them to be excessively priced.): https://setelec-shop.fr/148-haut-parleur-kef
And i think most people wants two way from them which is an error. They beg for 3ways and being relief from bass duties. At least it was the case for the ones i own/played with.
I don't think there is limited offer on coax. There is limited offer on 'hifi' targeted drivers though... but i'll never get the difference between 'targeted' offer. A driver is a driver, it does what you expect it to do, or not.
About room, well +1 with Mr Klinky and Mayhem13.
@pawelp if you are located in EU then there is a source for Kef spare parts if you are interested in playing with them ( and considered you have a tweet+mid+waveguide i don't find them to be excessively priced.): https://setelec-shop.fr/148-haut-parleur-kef
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Yeah the significant difference between various types of point-source systems is their directivity, off-axis response, which is very big part how a loudspeaker sounds in a domestic room.
In a box (room) there is usually at least six surfaces for first reflections to occur and arrive to ear. Unattenuated these would totally trump direct sound if they all arrived at same time makinf on-axis sound irrelevant but due to arriving within few milliseconds after and some other things that happen with long and short wavelengths the midrange is affected mostly. Effect gets less as the reflection is attenuated by acoustic treatment and/or speaker being more directive. It is very important not to disregard these as unimportant for speaker system. MTM, or array, can knock out more of the vertical early reflections than other topologies but only for the bandwidth there is narrow vertical directivity to the incident angle.
On the otherhand if these reflections are close replica of direct sound perhaps they don't matter at all as they wouldn't color the sound.
This might sound heresy but I haven't been able to simulate MTM whose response towards vertical early reflections wasn't worse than that of optimized stacked MT system or coaxial. Don't get me wrong though, if the significant midrange has narrow directivity, for the bandwidth that affects direct sound most, it is so much more attenuated that it probably doesn't matter the response is off.
My conclusion from this reasoning, not exactly knowing how hearing system actually works with vertical reflections, is that contribution of first vertical early reflections can be minimized with all of the systems by just making the response similar to on-axis or attenuate it enough.
In a box (room) there is usually at least six surfaces for first reflections to occur and arrive to ear. Unattenuated these would totally trump direct sound if they all arrived at same time makinf on-axis sound irrelevant but due to arriving within few milliseconds after and some other things that happen with long and short wavelengths the midrange is affected mostly. Effect gets less as the reflection is attenuated by acoustic treatment and/or speaker being more directive. It is very important not to disregard these as unimportant for speaker system. MTM, or array, can knock out more of the vertical early reflections than other topologies but only for the bandwidth there is narrow vertical directivity to the incident angle.
On the otherhand if these reflections are close replica of direct sound perhaps they don't matter at all as they wouldn't color the sound.
This might sound heresy but I haven't been able to simulate MTM whose response towards vertical early reflections wasn't worse than that of optimized stacked MT system or coaxial. Don't get me wrong though, if the significant midrange has narrow directivity, for the bandwidth that affects direct sound most, it is so much more attenuated that it probably doesn't matter the response is off.
My conclusion from this reasoning, not exactly knowing how hearing system actually works with vertical reflections, is that contribution of first vertical early reflections can be minimized with all of the systems by just making the response similar to on-axis or attenuate it enough.
@krivium
I do not have specific expectations here I just think it is the best open public place to exchange views on audio design on this planet. The contributions in this thread so far have been quite valuable 🙂
As for the coax I have played with it is http://www.seas.no/index.php?option...=480:h1699-0806-mr18rexxf&catid=52&Itemid=464
It looks actually quite good on paper. Not going into sound perception subjectivity that I not fan of either I was disappointed to measure that their acoustic centers are actually not aligned.
The sentence about mastering community voice was more an allusion to the earlier posts and more about my audio design priorities of time over frequency and was not meant as a call for opinions on the MTM vs coax strictly 🙂
I do not have specific expectations here I just think it is the best open public place to exchange views on audio design on this planet. The contributions in this thread so far have been quite valuable 🙂
As for the coax I have played with it is http://www.seas.no/index.php?option...=480:h1699-0806-mr18rexxf&catid=52&Itemid=464
It looks actually quite good on paper. Not going into sound perception subjectivity that I not fan of either I was disappointed to measure that their acoustic centers are actually not aligned.
The sentence about mastering community voice was more an allusion to the earlier posts and more about my audio design priorities of time over frequency and was not meant as a call for opinions on the MTM vs coax strictly 🙂