Have you heard, one time in your life, an advanced multisub configuration ?
Advanced multisub configuration : as many subs size, types and number as requied by the room modes managed by a DSP.
If a JBL Synthesis BassQ system fits that description, I did.
I've heard some Dynaudio studio monitors with multiple subs as well and other systems that were often optimized for specific rooms and purposes (i.e. mastering/monitoring/cinema).
In general, but this is strictly my personal opinion, I find such systems to sound very accurate, clean etc. but don't necessarily want these in my living room.
1. I understand the impact of room optimization (treatment) and multiple subs to get an even response (cancel standing waves etc.) > to get the room out of the way of the loudspeakers
2. To do this right, a considerable investment has to be made (monetary aka time)
3. You'll end up with 2,4,8 additional boxes.
4. Once you've set things up properly, you cannot just change things in your room (move furniture etc.) without messing up your calibration/response.
To cut, what could become a very long story, short: a multi sub setup is impractible for spaces that are anything but "Controlled". For this an other reasons I like to tune cabinets close to 0.0707, in order to have at least some versatility and adaptability.
I've heard some Dynaudio studio monitors with multiple subs as well and other systems that were often optimized for specific rooms and purposes (i.e. mastering/monitoring/cinema).
In general, but this is strictly my personal opinion, I find such systems to sound very accurate, clean etc. but don't necessarily want these in my living room.
1. I understand the impact of room optimization (treatment) and multiple subs to get an even response (cancel standing waves etc.) > to get the room out of the way of the loudspeakers
2. To do this right, a considerable investment has to be made (monetary aka time)
3. You'll end up with 2,4,8 additional boxes.
4. Once you've set things up properly, you cannot just change things in your room (move furniture etc.) without messing up your calibration/response.
To cut, what could become a very long story, short: a multi sub setup is impractible for spaces that are anything but "Controlled". For this an other reasons I like to tune cabinets close to 0.0707, in order to have at least some versatility and adaptability.
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Sorry, it is just one more thin line in the topic, but i feel that you are focusing on the cabinet only, instead of considering that that cabinet is all around you.
I made almost all of my designs in both active and passive versions. The differences are measurable, but audibly its very hard to tell the difference. This is why I have always said that active is easier, but not necessarily any better.
The speakers I made for myself (NS-15) are currently active, but implementing them in a home theater in 7.1 proved to be a real PITA. SO I am going to rebuild all of them passive just to make the setup more reasonable.
Yes, size can be an issue in many circumstances. I wish that one could make a smaller speaker as good as a larger one, ... but the physics of the problem are opposed to this.
Yowza! How many seats is that?
Back when I lived in Oregon I had an entire floor of my house that I never used. About 900'. I'd love to have a project like that.
I had a chance at that at my last place. I got to build a wing off the house, about 1000 sq ft.
I was able to build the dimensions for good modal dispersion.
And then be able to treat it acoustically for an even RT60 throughout the spectrum.
Wife just grinned and said, go Mark go, bless her heart !
Awesome sounding big room.
And then, being a typical audioholic, I put in an over the top 5.X... not sure what to call X?
Big bad Meyer mst4a's for mains, "little
" beautiful upa-1p's for center and rears, and a 650-p sub for rear! These were all flown from ceiling in the room, ......(damn mts4a are 280 lb.)
Lord what sound.
But....grin...when all that wasn't quite enough bass , corner stacked labhorns picked up the slack.
We all need some way to play like this, i think, i wish....
Just thought you guys might like to hear about another over-the-top...from one of us...
"instead of considering that that cabinet is all around you." > I don't understand what you exactly mean by this. Multiple subs perhaps?
Assuming a 2-way hornloaded or BR system, isn't it the size of the cabinet you are willing to accept or can accommodate that, to a certain extent, defines the size of a suitable horn?
I guess, the previous posts are quite illustrative in this regard.
But if you think you could make (big) radial horns work with small cabs or get 100dB sensitivity with decent bandwith from a 15" in 25L, I am more than happy to learn how.
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After re-reading this article on the development of the JBL M2, I thought it might me useful to refer to it once more in view of this thread.
There are some issues related to this thread that are covered in this article.
First off: the M2 waveguide was indeed designed to smear reflections.
Unfortunately Charles Sprinkle doesn't mention any specifics of how this actually works. From his quote one might conclude he refers to edge diffraction (only).
Furthermore the knuckles are brought in from the side in order to maintain patter control higher up.
Finally, one of the important stages in prototyping horns at Harman is indeed shape optimization, in which a.o. the acoustic pressure field is computed by finite-element solutions of the governing Helmholtz equations.
If you compare the older PT waveguides to the recent Image Control waveguides, it's obvious that JBL continued and improved on the design process that was initially used (and patented) for the PT waveguides. The method outputs a full set of performance metrics including throat acoustical impedance, acoustical transfer function from throat to mouth, near-field and far-field frequency response at arbitrary off axis locations, and beamwidth.
In essence, the PT and Image Control waveguides are much the same. I've included 2 images from a CAD drawing in which similar features can be distinguised, including knuckles that mitigate the diffraction slot.
It's highly unlikely the shape of the M2 was chosen for cosmetic reasons. The M2 is first and foremost developed as a Master(ing) Studio Monitor with an active crossover to be used in combination with dsp.
"Cosmetics" are way down the list of requirements of the targeted customer base (recording studios, mastering facilities etc.)
If it was a design factor at all, it would make far more sense to use the M2 waveguide for the 4367, which is the consumer version of the M2 (4367 is passive)
If you compare the waveguides of JBL's studio monitor speakers to those from the Synthesis line-up there is one specific characteristic that stands out.
The studio monitors, aimed at near/mid field listening feature waveguides that are more symmetrical, with more pronounced "knuckles" while the waveguides of the full range Synthesis speakers look more traditional.
Compared to the 4367 the waveguide of the M2 appears to be more shallow with a larger frontal surface and 120 (H) x 110 (V) coverage.
Within the Synthesis line there is an exception: the recently launched SCL In Wall series, that use a WG similar to the M2 (image below).
You saw this coming: these are intended to be wallmounted in a multi channel cinema setup and could be located quite close to some seats > nearfield.
I couldn't find the specified coverage angle of the 4367, but found this comment by Greg Timbers (ex-JBL) on Audioheritage:
"The M2 does better in this regard because the horn is symmetrical in pattern and designed to have a significantly wider coverage pattern. That just can't be done in such a compact horn as those in the 4367 and 4365. BTW, those two horns behave very similarly with neither having a major edge on the other in measured performance. They are not, however interchangeable physically and would require different EQ."
A logical conclusion: the shape is related to dispersion and intented distance to the listener (short vs. medium throw). In studio's even large fullrange monitor like the M2 are sometimes used nearfield.
For those who don't want to read the whole article: This part, in which Charles Sprinkle comments on the M2, is the most relevant to this thread (in the last sentence Sprinkle also refers to the importance of cabinet dimensions in developing the M2):
“The Bi-Radial horn that we have had for decades was a 90x60 horn, and not the best match for the low frequency device in the M2,” Sprinkle says. “This horn is 120 degrees horizontal and 110 degrees vertical. We knew that if we wanted a good directivity transition between the woofer and the high frequencies, we had to have that amount of pattern, so the waveguide was designed to have a pattern consistent with what the woofer was doing with no discontinuity at the crossover point, which is 800 Hz.
“The second thing we did was use a blending geometry—there are no straight lines, you’ll notice—that has a generally decreasing radius,” he continues, “forming an infinite number of reflections, and the net effect is that it smears the reflections coming back down the horn and negates them.
“The third thing we did is bring these ‘knuckles,’ which is a name that sort of stuck, in from the side so that rather than having this 1.5-inch aperture that we had in the Bi-Radial design, we were able to get the upper pattern control frequency up near 10k, much like it would be with a 25mm dome. You combine that with a high-frequency device that has the internal damping characteristics this driver has, and it sounds like a silk-dome! That nice, sweet, effortless, open sound. In the process, that directivity characteristic in the mid-band went away. Alan was really a champion of doing the right thing with the architecture: driver placement, making the cabinet taller—that opened the door to the work that was done on the waveguide.”
From the same thread on Audioheritage I referred to before, you can learn the 4367, and to a lesser degree the M2, is a rather compromised loudspeaker. Partly due to the limited usable bandwith of both 2216Nd and the 2430K.
Compromised by using off the shelf drivers that were not specifically designed or optimized for these loudspeakers. Compared to "the average high-end multi driver tower", the M2 and 4367 are dynamic speakers, but relative to their size these are not high sensitivity designs and definately not meant to be used with low power SET amps.
Contrary to what some may conclude from their price tag: both the M2 and 4367 are NOT by any means "cost-no-object" products.
For an example of a true cost-no-object loudspeaker, have a look at the Living Voice Vox Olypians and its "budget" brother: The Vox Palladian. (These are among the few high-end loudspeakers I have to hear some day).
Greg Timbers:
"There are a ton of misconceptions regarding the speakers. I can comment through the DV run after which I was no longer involved. The speaker is essentially similar to a 4365 in overall sound performance. There are some voicing differences partially due to my desires and partially as a result of the hardware used. The 2216Nd has the low TCR wire and is very kicky and dynamic as a result. The 2430 needs to be used an octave below where it is happy (as in the M2) and has an increased amount of 2nd harmonic distortion between 750 Hz and 1500 Hz as a result. It is not horrible, but it is about 10 dB higher than the 476Mg in that range and up to 20 dB higher than the 476Be over the same octave. The increased second comes from the 2430 being a ring radiator with no suspension. It is just difficult for it to move below 1500 Hz. The Mg diaphragm is twice as thick as the Be diaphragm so it resists motion in that range to a degree. The Be has the most freedom to move in the octave at and above crossover so it is the best of the three in that regard. With that said, the 2430 has a very detailed and musical sound and is a fine driver. It is capable of much higher output levels than any of the 476 family and is therefore well suited to Sound Reinforcement and Studio use. There is no silver bullet. With good things come bad things and one has to look at the total set of compromises. The 2430 is also about 1/3 the cost of the 476 precious metal drivers."
And:
"The design goal of the 4367 was to equal or surpass the performance of the 4365 in a smaller enclosure and for 1/3 less money! Done and Done. The system will thrive on LF EQ. There is plenty of headroom in the woofer so 4 - 6 dB of boost around 32 Hz will really spice up the mix.
The 4367 is a good system for those who like the large Monitor format. It measures well, sounds detailed and musical but is lean in the bottom octave as are all of the post 1985 or so "Japan" product. The speed and excess excursion capacity of these systems makes them good candidates for EQ, or for the proper use of a subwoofer, say below 40 Hz. They do have a "live music" sound that is most difficult to achieve purely with direct radiators. If you are looking for an Audiophile loudspeaker with 3-dimensional imaging, a warm mellow midrange and no dynamics at all, look elsewhere. Without using the words Distilled Water you might look at another Harman brand if you are seeking elegant, luscious elevator music."
M2: Dimensions (H x W x D): 1256mm x 508mm x 355.6mm (49.5in x 20in x 14in).
4367: 941mm x 560mm x 425mm (37-1/16" x 22-1/16" x 16-3/4").
Finally, the M2 is much higher, which corresponds to a listening height that is more adapted to taller western body types, compared to the 4367, which is specifically designed for the Asian market and is to be used on stands of at least 7" to elevate them to ear height.
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Let me offer my perspective on this discussion.
Back in 1919 I published an AES paper using the term "waveguide" for the first time referencing an acoustic horn-like device. (For reasons that I have elaborated on at my website.) In this paper I showed how one could design a device that had the desired directivity with a minimum of internal reflections and diffraction. Following that paper, I entered into a contract with JBL, through my friend John Eargle, to develop such devices. However, shortly after that a change in status whereby my employer at the time - Ford - became contractually tied to JBL, and my association with JBL was deemed to be a conflict of interest and the contract was terminated.
My approach to this problem was also shown to be optimal by a PhD thesis in AUS that showed numerically that my curvature was in fact the ideal one to achieving a constant directivity device with minimal internal reflections.
Hence, clearly, the problem that JBL was trying to solve in their "waveguides" had already been solved, but for some reason they chose not to use it (it's not hard to see why they would want to do that.) What they came up with may work well - I have never seen accurate data on them - but I would place a bet that it does not work any better than, and probably worse, than my own approach.
Does this mean that the changes were done for "cosmetics"? Hard to say, but it does appear that they wanted something unique, rather than using something that had already been proven.
Back in 1919 I published an AES paper using the term "waveguide" for the first time referencing an acoustic horn-like device. (For reasons that I have elaborated on at my website.) In this paper I showed how one could design a device that had the desired directivity with a minimum of internal reflections and diffraction. Following that paper, I entered into a contract with JBL, through my friend John Eargle, to develop such devices. However, shortly after that a change in status whereby my employer at the time - Ford - became contractually tied to JBL, and my association with JBL was deemed to be a conflict of interest and the contract was terminated.
My approach to this problem was also shown to be optimal by a PhD thesis in AUS that showed numerically that my curvature was in fact the ideal one to achieving a constant directivity device with minimal internal reflections.
Hence, clearly, the problem that JBL was trying to solve in their "waveguides" had already been solved, but for some reason they chose not to use it (it's not hard to see why they would want to do that.) What they came up with may work well - I have never seen accurate data on them - but I would place a bet that it does not work any better than, and probably worse, than my own approach.
Does this mean that the changes were done for "cosmetics"? Hard to say, but it does appear that they wanted something unique, rather than using something that had already been proven.
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IMHO the multisub configuration is not a concept or a degin rule, when you are considering the room as a internals of a baffle you simply fight against the enclosure issues with better accuracy by defocusing ond the emissive device and expand your POV to its perfect integration to the environement without paying too much credit to "what you want or what you feel".
My room is the real designer of my multisub setup, it decides where i put the emissive devices and what are their technical requirements, i've chosen nothing at all.
I'm building a Geddes inspired desing apdapted to a small bedroom for a near field very low listening level purpose.
The goal is to keep the sensivity as high as possible around the multisub crossover frequency and an Eminence Delta15A2 can reach more than 97dB at 100Hz (25L-1.10Q)
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Wow, that's a mouthful of a sentence, but for the life of me I can't figure out what it means.
In a inverted sense, that's what everyone does right? We fit the system to the room, not the other way around.
"Inspired" in what way?
For me it means that the concept of two hifi loudspeakers able to cover the widest possible frequency range and radiating exclusively in front of the listener is an outdated concept.
The emissive devices fits the room like we try shoes, i have 5 very different kind of subwoofers (Closed, BR, OB, with loudspeakers drivers of Ø20cm to Ø46cm) and i map and test each position on each frequency range with each loads in order to see the effects on the CSD.
A B&C DE250 in a OSWG crossed at 1200Hz with a 12' and a multisub configuration under 100Hz.
Finally replaced the OSWG by a exponential horn 60x80 in order to reduce the reflexions and made a very personal subwofer configutation because of the room topology.
Edit : And shrinked a lot the front loudspeakers AND made an infidelity to B&C
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That's an odd statement. Outdated because its only two channels? That's what stereo is. I wasn't aware that two channel was going away anytime soon. It's still the dominate source material.
I'm talking for a stereo setup and i'm perhaps too generalising but i only know very few people that have large rooms dedicated to audio and in barely all small rooms that i've seen, the bad (only aestetical) placement of the front loudspeakers was causing large uncomfortable spikes and nulls in the FR under 150Hz.
I've also very, very often heared that the small rooms can only and exculsively accomodate of very small loudspeakers and so ..the hifi seems to die of extreme loudspeaker shrinkage.
To me what you say is not the case. Small rooms can utilize large speakers very well, it's just that manufacturers would have you believe that their small speakers work best, because that's what the customer wants to hear. SO they buy ever smaller speakers and get ever poorer playback quality. It's simply the market trend, ala Bose. It's wrong, but that doesn't seem to matter to people.
SO true!