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In Reply to: RE: Maybe I'm not an audiophile posted by G Squared on October 23, 2016 at 16:43:08
You mentioned that you are looking for "Immersive like a concert."Concert hall designer, researcher, and psychoacoustics expert David Griesinger uses the word "envelopment" to describe the sound in the best seats in a good concert hall, and I think he is talking about the same thing.
From one of his papers on concert hall acoustics:
"Envelopment is perceived when the ear and brain can detect TWO separate streams:
"A foreground stream of direct sound.
"And a background stream of reverberation.
"Both streams must be present if sound is perceived as enveloping."
Also, "When presence is lacking, the early reflections are the most responsible.... Presence depends in the ability of the ear and brain to detect the direct sound as separate from the reflections that soon overwhelm it."
In my opinion, Greisinger's observations about what works well in the concert hall are not only brilliant, but are also applicable to the home listening room, because the relevant characteristics of human hearing stay the same.
Translating these concepts into a home listening environment, there are actually THREE elements that must be present:
1. A very clean and precise foreground stream of direct sound.
2. Freedom from early reflections.
3. A well-energized background stream of relatively late-onset, spectrally-correct reverberant energy.
I call this the "Two Streams Paradigm", for obvious reasons.
The criteria for the Two Streams Paradigm can be met by a speaker that is highly directional (to minimize early reflections), which also generates additional spectrally-correct reverberant energy that arrives at the listening position after a decent time delay (10 milliseconds is good). Relatively few speakers do this. Room acoustics obviously come into play, but unless we're ready to spend a lot of money, the room's ability to "fix" the speakers is limited.
You also mentioned that you are looking for this: "The drums hit, the piano bites and the cymbals sparkle."
Musicians use dynamic contrast to convey emotion, so a speaker that fails to preserve the dynamic contrast on the recording will fail to convey this emotion. Briefly, the solution is to use drivers with sufficient thermal power handling that they are just loafing along at maybe 10% of their rated AES power handling (not "music program") even on maximum peaks, so that there is no short-time-constant thermal modulation of those peaks (a phenomenon that Floyd Toole acknowledges has not been adequately investigated yet). In general high efficiency speakers provide this freedom from thermal effects, as do speakers that use prosound drivers.
Even fewer speakers combine a Two Streams Paradigm compatible radiation pattern with the kind of thermal headroom needed to preserve the peaks (mechanical headroom is also needed, but typically by the time we're at power levels that get into mechanical compression, we're well past the thermal thresholds).
Of course a speaker must do more than have the correct type of radiation pattern and sufficient thermal headroom, but these characteristics cannot be added later in the design process, so arguably they make a good starting point.
Imo, ime, ymmv, etc.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 10/25/16 10/25/16 10/25/16 10/25/16Follow Ups:
From all that I've read it is the minimum delay desirable, not the absolute target.
Fortunately, sound travels at close to one foot per millisecond, which makes calculations easy. Thus with dipole speakers as Duke suggests, placement should be at least 5' out from the front wall. Then rear waves will travel to the wall and back even with the front of the speaker, delayed by at least 10 ms, before continuing on to the listener. That can maximize the spaciousness of dipoles.
Similarly in considering first reflection points from sidewalls, the distance from each speaker to the reflection point on the sidewall and then to the listener's ear should be 10' greater or more than the distance from the speakers directly to the listener for the desired perception separation.
When these distances out from the front wall or to the sidewalls cannot be achieved by physical placement then some form of treatment may substitute. Either dispersion (broad scatteration) or reflection elsewhere than the listener position can be added.
"The piano ain't got no wrong notes." Thelonious Monk
Ten milliseconds is about where the reflections become clearly beneficial; before that they're more of a mixed blessing, and arguably outright undesirable before 6 milliseconds ( < < < that's my own opinion based on experimenting with dipole distance from the wall).
I make 10 milliseconds my target because it works and can usually be achieved; 15 milliseconds or more would be better but is a lot harder to achieve within normal room dimensions. James Romeyn and I tested his LCS concept in a facility with 16 foot ceilings and it worked very well, giving a sense of envelopment and soundstage depth that extended well beyond the plane of the wall behind the speakers.
One way to get 10 ms of sidewall delay is to use speakers that have a 90 degree radiation pattern in the horizontal plane and then toe them in very aggressively, like at 45 degrees. This way the left speaker's first significant sidewall bounce is off the right side wall, and vice versa, so the path lengths are pretty long. I use this trick too, which I learned from Earl Geddes.
Earl goes on to intercept the floor bounce with a judiciously placed coffee table, and he has vertical "slats" on the ceiling to break up the ceiling bounce. Note that in both cases he's not using absorption, so as to preserve his later-arrival reverberant energy.
On the other hand, Toole found that early reflections are desirable, so Earl and I disagree with him on this topic (not that my opinion comes with any of the credentials that Earl's does). I'm not sure of the exact methodologies that led to Toole's conclusion, and I don't know whether he tested early reflections vs late reflections for their relative desirability, as I think he was mainly investigating the radiation pattern width of conventional direct radiator speakers.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
I checked out your website. I assume you're talking about this:
http://www.audiokinesis.com/dream-maker-lcs.html
Looks like a controlled dispersion main speaker with some rear radiators, combined with a second effects speaker on the floor against the wall. Although the effects speaker is on its back so the peak of its radiation pattern is pointing at the ceiling, it is also going to radiate like an omni in the horizontal plane and produce a strong reflection off the front wall that will arrive just a few ms behind the main speaker, even earlier than the front wall reflection from a typical speaker.
In the picture from RMAF below, the effects speakers are in the corners. That position should produce a strong early reflection out of the corners, like that from a dipole or bipole but arriving in half the time.
I get that there will be a later reflection from the ceiling, but it looks like you're also adding early reflections and I can't square that with what you're saying about reflections being outright undesirable before 6 milliseconds.
It would seem to me that you could reduce the amount of radiation from the effects speaker onto the wall and delay the arrival of the front wall reflection just by moving the effects speaker out from the wall so it's directly behind the main speakers. Perhaps you've tried that and it didn't sound as good, but it would seem to better match the theory.
Another idea would be to place an upward firing 2-3" wideband driver on the top of each speaker in a shallow waveguide, perhaps recessed a bit with a ring of absorber around it just to make sure it doesn't contribute anything to the direct sound.
The upfiring array in the photo you posted consists of two 8" woofers and a 90-by-45 degree horn, in an "MHM" arrangement. The secret weapon is the main speaker - it acts as a "shield" so that there is no direct path between the LCS (Late Ceiling Splash) speaker and the middle of the listening area.
So yes there will be some earlier-than-ideal contribution from the LCS speakers, but it is minor, especially in comparison with the amount of energy that arrives after bouncing off the ceiling and upper walls.
I don't remember why we ended up putting the LCS speakers back in the corners. It may have been so that we would walk around in that area. In general placing them right smack behind the main speakers does work better, I think, and maybe we hadn't figured that out yet (that speaker system was the first of the breed and was completed just barely in time for the show).
As far as placing upfiring drivers on top of the main speakers, that works pretty well and has been done by Linn, Ohm, and Lowther USA. Most of the Shahinian models are variations on the theme - his angles are well thought-out. That being said, imo there are improvements from having the additional drivers firing up from the floor so that we a) get that longer time delay and b) can use the main speaker as a "shield" to block any early-arrival energy from them.
Of course long wavelengths from a monopole source are going to have wide radiation patterns and will just flow right around obstructions like the main speaker cabinet, but they are subjectively less critical. Theoretically good pattern control down to about 700 Hz is sufficient, based on a couple of my sources, and the upfiring array in the photo gives us that in the dimension that matters most.
Further improvement could probably be made by using electronic delay, in which case other geometries become quite feasible.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Golly, to read what you guys write, a person would think that Earl Geddes and Floyd Toole were the only two guys who ever researched this stuff. :)
I've been reading research papers on psychoacoustics since the mid 1970s, and working with audio systems since before that, before I quit college as a music major in 1975 (I veered off into audio and acoustics instead of music). Anyway, this whole "2 ms, 6 ms, 10 ms, 20 ms" stuff is making me gag.
YES!, there IS a threshold between where a reflection 1) Changes the character of a sound, 2) Changes the apparent location of a sound, 3) Interferes with the 'definition' of the sound; and, it varies with the type of sound, and these effects vary with both sound level and frequency.
Duke, I'm not raggin' on you, but in the "audiophile" world, many people are SO clueless about acoustics and psychoacoustics. To me, your comments are well-taken and useful. The thing is, the audience for your comments needs more depth in order to understand the topic, and you're over-simplifying it. Generally speaking, I'd say you're on the right track. (See my post from a couple years ago. LOL)
One of the bottom lines is that "audiophiles" should get at least a basic understanding of acoustics and psychoacoustics.
:)
From my reading on acoustics I thought Bell Labs identified the importance of at least a minimal separation between direct sound and reflected sounds for reason of clarity -- minimizing sonic smearing. Unfortunately I don't have a specific reference for that.
"The piano ain't got no wrong notes." Thelonious Monk
Auditory thresholds are usually somewhat fuzzy in the time domain, and reflection detection thresholds do indeed vary with level and frequency and direction, and the subjective effect of said reflections likewise varies. But if the question is a practical one like "how far do my Maggies need to be out from the wall for the magic to happen?", then that answer is going to translate into a path-length-induced time delay that is the same at all frequencies. What I'm doing isn't exactly the same as the Maggie situation, but it's pretty close. So that's why I'm not talking about the effects of different delays at different frequencies.
Just for the record, in addition to Toole and Geddes and Greisinger, my sources include "Spatial Hearing" by Jens Blauert and an assortment of AES articles by various authors. But Toole and Geddes are the ones who the most into practical applications relevant to loudspeaker systems in home listening rooms.
Now if the question is "what matters most - getting the reflections to arrive from the ideal direction, or getting a bit more time delay?", the answer cannot be found in the published literature. It has to be determined experimentally. James Romeyn's findings on this topic surprised me, as based on my understanding of Toole I'd have told him not to waste his time trying the upfiring geometry, but in practice it outperformed other geometries that resulted in a more ideal reflection direction but less time delay.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Psychoacoustics is a fascinating field. Heck, just for starters, it's kind of amazing that we can fool ourselves into thinking there's a band/orchestra spread across the living room wall - with only two sources!
Anyway, I'm in complete agreement that the up-firing driver is the way to go as a means of improving the ambient sound field. The one caution is that it not be too directional. Even though we're not very good at detecting the vertical location of a source, if the up-firing driver is too directional, it could actually be a contributor to a less-than-desirable ambient field.
One other thing... If you could build in a passive FR contour control, with maybe 4 - 6 setting choices, and a level control, that would be the tits.
:)
I agree that we would not want too strong and distinct ("specular") a reflection from the upfiring array, but in practice we're usually getting reflections off of both nearby walls as well as the ceiling, and so it hasn't been an issue with the radiation patterns I've been using. And the ear's reduced localization ability in the vertical plane probably helps too. I would guess that there is a tradeoff between narrow pattern to minimize any early-arrival energy vs wider pattern to give us a more diffuse "main" reflection, but in practice the physical size required to get very tight directional control down usefully far into the midrange is probably prohibitively large.All of my speakers (LCS and rear-firing arrays included) have an external resistor-in-a-cup that functions as a "tilt" control for the high frequency driver. I say "tilt" because changing the resistor value has more effect at 10 kHz than at 2 kHz, which I think is more useful than a "shelving" type control. I normally provide resistors for three different settings, but obviously someone who finds that an "in between" setting would be optimal can tailor the resistor value to that.
My more recent rear-firing or LCS arrays incorporate a level control with about 6 dB of range, and I could incorporate such into any future builds.
In most cases my LCS and rear-firing arrays have separate inputs, which means you can reverse their polarity. This can be useful for smoothing out the in-room response in the upper bass region. Actually having two bass/midbass sources per speaker that are a different distance from all three room boundaries helps in that respect all by itself, regardless of which polarity you use.
I have designed (and shown) a set of add-on LCS modules that could be added in parallel to many existing speaker systems without dropping the impedance too much, but I have not gone into production with it yet. Further testing is needed before I can say with confidence what range of circumstances it would be beneficial in.
Speaking of psychoacoustics, there is one other trick I do which I have not gone public with, something I learned from Earl Geddes and which is confirmed by a close reading of other sources. Psychoacoustics is indeed the neatest thing, it's like there are these little counter-intuitive backdoor entrances to the halls of sonic bliss.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 10/30/16 10/30/16
Or so it seems to me.
I love the music of Dmitri Shostakovich ...
Yes!
I'm been a multichannel advocate for a long time. With rear channels driven by analog (first) then digital delays since my dorm room (1976) with Dynaquad , then Advent 500 then to an HT processors and receivers. Each recording requires it's own optimization (which is a pain) but easier with modern remotes. Some recordings sound just fine in plain ordinary stereo, a some stereo recordings also take well to stereo playback with cross feed cancellation.
Lately I've been experimenting with remastering recordings and adjusting the presentation - for storage on my NAS. Fun stuff.
It's all about enjoying the music, the artists, and emotionally reacting to the performance.
"The hardest thing of all is to find a black cat in a dark room, especially if there is no cat" - Confucius
Posted by TAS reviewer Andrew Quint on another forum, about hearing a recording he was familiar with, made in a hall he was familiar with, played through a set of my "Two Streams Paradigm" speakers:"With the right audio gear, it [the recording Andrew had just played] successfully renders the essence of (IMO) one of the greatest 3 or 4 concert halls on earth, the Concertgebouw (thus the orchestra's name) in Amsterdam. I've heard music there, and there's truly a sense of sound being present in the air around you.
"The multichannel program on the RCO Live SACDs (there are dozens) get this aspect right; so did the Bienville Suite, nearly to the same degree, despite the presence of only two channels. My concern when Duke told me about the rear-firing drivers was that this would impart some generic, Bose-like spaciousness to the recording, but that wasn't the case—what I heard was the unique acoustic signature of the Concertgebouw."
So my speakers delivered the sense of being in the Conctrtgebouw "nearly to the same degree" as a multichannel system. So not quite as well, but not too far off either.
I suspect that the typical multichannel geometry that has you sitting almost in the nearfield of the surround speakers is sub-optimal, which is probably one reason why having a whole bunch of surround speakers sounds more natural than just having two, even if you aren't actually sending different signals to each surround speaker.
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 10/26/16 10/26/16
Relatively few speakers do this. Room acoustics obviously come into play, but unless we're ready to spend a lot of money, the room's ability to "fix" the speakers is limited.
It isn't the speakers that need fixing. It's the room.
The reverberation you hear in a good concert hall is complex, diffuse, omnidirectional. You hear a large number of multiple reflections from different directions at different delay times summing together. There must be enough reflections with enough diversity in direction and arrival time that the result is a statistical distribution rather than a recognizable pattern of echoes. That's what makes it sound like you're in the middle of an enveloping sound field rather than just in a really big room.
It is not possible to make the reverberation of a small room sound like the reverberation of a concert hall. Most untreated domestic listening rooms sound like echo chambers. By that I mean that their reverberant sound is dominated by temporal patterns from a few strong echos. Changing the radiation pattern of the loudspeaker can alter the balance of direct vs. reflected sound and the frequency response of the reflected sound, but that doesn't alter the reverberation characteristics of the room. You can never make a listening room sound like a concert hall, but you can make it not sound like an echo chamber by controlling room dimensions and room treatments.
My hunch is that your preference for bipoles is mostly related to the spectrum of the power response, and doesn't have much to do with the arrival time of the front wall reflection. The delay time for the front wall reflection in a typical listening room is 15-25 ms, which is still an early reflection that in no way resembles anything you hear in a concert hall.
Dave: It isn't the speakers that need fixing. It's the room.
Duke: They need to work together. Having heard what a professionally treated room can sound like, I readily agree that the room can make a huge difference. But imo there is significant room (ahem) for improvement in how speakers interact with rooms.
D: The reverberation you hear in a good concert hall is complex, diffuse, omnidirectional. You hear a large number of multiple reflections from different directions at different delay times summing together. There must be enough reflections with enough diversity in direction and arrival time that the result is a statistical distribution rather than a recognizable pattern of echoes. That's what makes it sound like you're in the middle of an enveloping sound field rather than just in a really big room.
D: Agreed. But reflections from some directions are more beneficial than from others, according to Toole, and we can still get psychoacoustically beneficial time delays in a home listen room.
D: It is not possible to make the reverberation of a small room sound like the reverberation of a concert hall.
D: True. But minimizing early reflections while preserving later ones IS beneficial, and having later-arriving reflections come from other directions will make it easier to hear the reverberation captured on the recording. Perceptually, the worst possible direction for reflections to arrive from is the same direction as the first-arrival sound.
D: Changing the radiation pattern of the loudspeaker can alter the balance of direct vs. reflected sound and the frequency response of the reflected sound, but that doesn't alter the reverberation characteristics of the room. You can never make a listening room sound like a concert hall, but you can make it not sound like an echo chamber by controlling room dimensions and room treatments.
D: By reducing the early reflections (those less than 10 ms behind the first-arrival sound), we get better clarity. By still having a decent amount of spectrally-correct later-arriving reflections, we still get good timbral richness and, as long as we don't have specular reflections, the image localization is preserved plus we get that sweet sense of envelopment.
D: My hunch is that your preference for bipoles is mostly related to the spectrum of the power response, and doesn't have much to do with the arrival time of the front wall reflection. The delay time for the front wall reflection in a typical listening room is 15-25 ms, which is still an early reflection that in no way resembles anything you hear in a concert hall.
D: Good power response is highly desirable imo, but anecdotal evidence from thousands of Maggie (and other dipole) owners says that the delay time DOES matter, and that about 10 milliseconds delay for the additional energy works quite well.
Of course it's not what we get in a concert hall, but the arrangement I advocate does a very good job of letting the you hear the reverberation on the recording, apparently not too far from what you'd get with a good multichannel system. See the post I linked to below.
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
This is an interesting theory, but questions must be asked as the theory is put forward by the manufacturer of a loudspeaker brand that attempts to comply with this theory! It may be valid - it may not! I'll put forward a few questions as "food for thought" only!
Firstly, is the theory itself valid? In a concert hall the reverberation is far far more than 10 milliseconds. However a small room in club or a pub may have reverberation time of this order.
Next, why should reverberation created by a group of live musicians exist in a room, but reverberation generated by conventional speakers not exist in one's listening? Perhaps the live venue is much larger than one's listening room, so it's more a matter of reverberation time.
Perhaps one could argue that the instruments in a band emit their sound in all directions. Well, imagine listening to a band (with trumpets, saxes, a singer, etc) with all the musicians facing away from you. Wouldn't the sound be most unsatisfactory? Live music is largely (but not wholly) directional - as are conventional speakers.
Conventional speakers are designed to send all their sound towards the listener, but most are still best placed away from back walls. Doesn't the back wall (indeed the whole listening room) still create a reverberation? In some rooms this is all too obvious, for example under-furnished rooms. The "echo" effect makes a mess of the sound. A properly furnished room or one with added room treatment should surely offer the right degree of short reverberation that one has in a small live venue.
If one wants longer reverberation such as experienced in bigger live venues or concert halls, one should perhaps be looking to delay (by an electronic circuit) a secondary sound signal - and perhaps have it come from rear and/or side speakers. There's no sign of this in the thesis above.
Then one has to ask why so few speakers offer the seemingly simple solution of back facing non-bass drivers. One or two other makers have backwards-firing drivers that seems similar in concept. With one the volume level was fully adjustable, but comments from owners seem to suggest that the sound was less "muddled" with little or no back-firing.
Doesn't the effect depend very much on the distance to the wall behind the speakers and the material covering the wall? Presumably to get this effect, one needs about 5 ft behind the speaker (sound travels 10 ft in 10 ms) and it has to be reasonably reflective of sound. This can be achieved in most homes, but certainly not in all - including mine unfortunately.
So the theory is one that has not been taken up by any of the big boys in the loudspeaker industry. One has to ask why not. Even top-of-the-range multi kilo-buck models almost never include this feature of back firing drivers. Are they all wrong? Is this "immersive" sound" feature only appreciated by a handful of listeners with the rest of us considering it "muddled sound"?
I don't know the answers but I'd love to try a pair of these speakers in my very definitely difficult listening room. No UK distributor unfortunately!
Cawson: This is an interesting theory, but questions must be asked as the theory is put forward by the manufacturer of a loudspeaker brand that attempts to comply with this theory!Duke: True!
C: Firstly, is the theory itself valid? In a concert hall the reverberation is far far more than 10 milliseconds. However a small room in club or a pub may have reverberation time of this order.
D: The basic theory of minimizing early reflections while preserving later ones is valid, and is usually approached from the angle of room acoustic treatment instead of speaker design.
While we can't replicate the concert hall's reverberation time, we can still make worthwhile improvements by a) minimizing early reflections while still b) preserving substantial relatively late onset reverberant energy... that is, "late onset" within the context of our small room sizes.
The "10 millisecond" target comes reading Earl Geddes and years of playing with full-range dipoles (SoundLabs).
C: Next, why should reverberation created by a group of live musicians exist in a room, but reverberation generated by conventional speakers not exist in one's listening [room]?
D: Reverberation definitely still exists in the home listening room, what we want to do is make it work WITH the first-arrival sound instead of AGAINST it. So we don't want it to start out too early, and we want it to be spectrally correct.
C: Perhaps one could argue that the instruments in a band emit their sound in all directions. Well, imagine listening to a band (with trumpets, saxes, a singer, etc) with all the musicians facing away from you. Wouldn't the sound be most unsatisfactory? Live music is largely (but not wholly) directional - as are conventional speakers.
D: We get our primary imaging cues from the first .68 milliseconds of the first-arrival sound, which works out to about 9 inches (corresponding to the distance around the head from one ear to the other). Then the "precedence effect" kicks in, and we largely (but not completely) ignore directional cues from repetitions of that original sound, i.e. reflections. But we still pick up timbre and loudness cues from those reflections, so they do matter. We also get our sense of the acoustic space from the reflections.
So I don't think that what I'm advocating is analogous to having the musicians face away from you... more on that in my next paragraph.
C: Conventional speakers are designed to send all their sound towards the listener, but most are still best placed away from back walls.
D: Conventional speakers generally have a wide but non-uniform radiation pattern that gets wider or narrower as we go up and down the spectrum due to the radiation patterns of the drivers. So let's say a conventional speaker has a roughly 180 degree radiation pattern. What I do with my pair of directional arrays (front and rear) is, chop that 180 degree pattern into two smaller 90 degree patterns, aim one at the listener, and then aim the other in a direction that gives us a lot more benefit than if it had gone into early reflections.
C: If one wants longer reverberation such as experienced in bigger live venues or concert halls, one should perhaps be looking to delay (by an electronic circuit) a secondary sound signal - and perhaps have it come from rear and/or side speakers. There's no sign of this in the thesis above.
D: Ken Kantor did exactly that years ago in the Acoustic Research "Magic" speaker. I believe a worthwhile improvement over conventional speakers can be made with a passive system done well.
C: Then one has to ask why so few speakers offer the seemingly simple solution of back facing non-bass drivers. One or two other makers have backwards-firing drivers that seems similar in concept. With one the volume level was fully adjustable, but comments from owners seem to suggest that the sound was less "muddled" with little or no back-firing.
D: Dipoles set up with sufficient distance behind them (5 feet or more ideally, 3 feet minimum imo) are a widespread example of a Two Stream paradigm setup.
There is such a thing as too much reverberant energy (cough cough Bose cough), and if the front-firing drivers already have a wide radiation pattern, adding rear-firing drivers may be too much. That's one of the reasons why I shoot for somewhat tighter pattern control with my arrays.
C: Doesn't the effect depend very much on the distance to the wall behind the speakers and the material covering the wall? Presumably to get this effect, one needs about 5 ft behind the speaker (sound travels 10 ft in 10 ms) and it has to be reasonably reflective of sound. This can be achieved in most homes, but certainly not in all - including mine unfortunately.
D: The up-firing (from the floor) configuration that James Romeyn came up with, which he calls "Late Ceiling Splash", allows placement of the speakers much closer than 5 feet to the wall.
C: So the theory is one that has not been taken up by any of the big boys in the loudspeaker industry. One has to ask why not. Even top-of-the-range multi kilo-buck models almost never include this feature of back firing drivers. Are they all wrong?
D: Again, a dipole speaker set up well is a Two Streams Paradigm system. Maggie, Quad, Martin Logan, SoundLab, etc.
If the big conventional speaker boys have decided against it, that's fine with me! The market seems to be more interested in uber-tech driver diaphragms than in psychoacoustically beneficial room interaction anyway. In order to do it right, imo they'd have to get much more aggressive with their radiation pattern control, and that means big cones and/or horn-like devices, both of which put off most audiophiles. I'm small enough that I don't need much market share.
C: Is this "immersive" sound" feature only appreciated by a handful of listeners with the rest of us considering it "muddled sound"?
D: There are tradeoffs virtually every step of the way in speaker design (and anyone who tells you differently is in marketing). I don't want too much reverberant energy, hence the narrower-than-normal patterns that I use. Remember that it is the early reflections that degrade clarity the most, which is one reason why a good horn system can have such good clarity. But horn systems tend to sound a bit dry, so another way of looking at my approach is, I'm retaining the freedom from early reflections of a good horn system but doubling up on the beneficial later reflections.
C: I don't know the answers but I'd love to try a pair of these speakers in my very definitely difficult listening room. No UK distributor unfortunately!
D: Tell me more about your room, if you don't mind.
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 10/26/16 10/26/16
Hi Duke
Many thanks for explaining more about your system. I suspect it's the sort of solution that can really only be judged by a home trial.
My Profile briefly describes my room and my existing equipment. You'll notice that I have Avantgarde horn speakers and a varied choice of excellent amps.
Overall dimensions are - 31 x 48 x 7'8"
Vast (975 sq ft) almost semi-circular (actually more parabolic!) room with floor-to-ceiling glazing on most of curved wall.
Low ceiling height. Acoustically challenging!
I should add that the speakers are placed either side of a large central column and they face ACROSS the room, not towards the flat end or the pointed end.
When I return home next week I'll send you a layout sketch of the room by PM if I may.
The Avantgardes sounded great in my London living room (5 sided with big bay, 350 sq ft, 10 ft ceilings and nice soft Victorian plaster walls) but they're sadly not so happy in my new pad.
Suggestions, suggestions welcome!
Thanks
Peter
Thanks for your kind reply!
"The Avantgardes sounded great in my London living room (5 sided with big bay, 350 sq ft, 10 ft ceilings and nice soft Victorian plaster walls) but they're sadly not so happy in my new pad.
"Suggestions, suggestions welcome!"
My impression is that Avantgardes absolutely nail the first-arrival sound, and that their strong directional control makes them much more free from early reflections than most speakers (including my own). Their horn flares are not constant directivity, which implies that their reverberant fields are going to have a somewhat different spectral balance than the first-arrival sound, but they are still considerably better than most speakers in this respect.
IF the problem in the new room is that your Avantgardes don't have the timbral richness, particularly in the midrange, that they had in your London room, that could be related to the relatively weak reverberant field we get with highly directional speakers, combined with the long reflection path lengths (which means that the reverberant energy will be attenuated by distance moreso than normal). A well-energized reverberant field promotes timbral richness. As an extreme example of the effects on timbre of the reverberant field in a small room (the opposite end of the spectrum from your new room), imagine singing in the shower.
It is also possible that you are getting considerably less boundary reinforcement in the bottom few octaves in that large room, which can make the speakers sound "thin", and if this thinness extends into the lower midrange, it may be beyond correction via the controls for your powered woofers.
If either of these guesses are in the ballpark, I might have an idea or two. You can e-mail me at audiokinesis at yahoo dot com.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Is likely a factor in whether you want to simulate the reverb through playback system design.
The ear/brain system is better able to pick out the reverberant information in the recording when it's presented this way, versus when it's presented conventionally. In fact, the worst possible direction for reflections to come from is right smack from the same point as the first-arrival sound! This from Floyd Toole, I can elaborate if you'd like.At Axpona this past April, TAS reviewer Andrew Quint came into Brian Walsh's room where we had my speakers set up. After listening a bit and hearing my schpiel, he said (paraphrasing), "Won't the room's signature just mask the acoustics on the recording?"
I boldly replied, "No, in fact you will actually hear MORE of the recording venue, not less!"
Andrew challenged that by pulling out a thumb drive and asking us to play a recording made in a concert hall that he was familiar with. Afterwards, when I asked what he thought, he said "It's not a gimmick, it works."
He later came onto my Audio Circle forum and posted this:
"I'll elaborate a bit on the recording in question and what I heard in my brief audition of Duke's new speaker.
"The recording was a FLAC rip of the CD layer of an RCO Live SACD: Shostakovich—Symphony No. 15; Concertgebouw Orchestra/Bernard Haitink conductor. It's a live recording from March of 2010 (Haitink made a much earlier recording of the same piece with the London Philharmonic; he was the first person to record all the Shostakovich symphonies.) For a couple of years, this has been my go-to symphonic recording when I have just a short time to get a sense of an unfamiliar system. It's an excellent performance, something I can listen to repeatedly without going nuts, which is important at a show. In terms of audiophilia, it's an extremely detailed yet atmospheric representation of an orchestra, with excellent dynamics and fully characterized instrumental colors (bells, solo turns by violin, flute, piccolo, string bass, trumpet, etc.) And—with the right audio gear—it successfully renders the essence of (IMO) one of the greatest 3 or 4 concert halls on earth, the Concertgebouw (thus the orchestra's name) in Amsterdam. I've heard music there, and there's truly a sense of sound being present in the air around you.
"The multichannel program on the RCO Live SACDs (there are dozens) get this last aspect right; so did the Bienville Suite, nearly to the same degree, despite the presence of only two channels. My concern when Duke told me about the rear-firing drivers was that this would impart some generic, Bose-like spaciousness to the recording, but that wasn't the case—what I heard was the unique acoustic signature of the Concertgebouw.
"So, a splendidly realized design - a pleasure to listen to."
Andrew included my speaker system in his "Most Significant Products" list show report.
From time to time at this show, and at others, I'd turn the rear-firing speakers off and on and ask people whether they thought they were hearing "more recording" or "more hotel room" with them on. Nobody said "more hotel room" (at least not to my face!).
Here are some comments from the 2013 Rocky Mountain Audio Fest, by Tyson and Jason (aka "PEZ") from Audio Circle. First Tyson sat in the sweet spot, and then they switched places, and this is what they wrote:
(Tyson)"Saint-Saens Violin & Piano - Maybe, no definitely the most beautiful presentation of this track at the entire show.
"Handel Aria - Ditto, just beautiful. I really expected the imaging to be washy in this room, due to the LCS [Late Ceiling Splash] technology. But the image is rock solid center. And a lot of ambiance stretching WAAAAYYYYY back, way past the physical boundaries of the room. Side to side imaging is not as impressive, but still very good.
"Mahler Symphony - Really nice, big spacious open sound. Again, it actually expands beyond the physical confines of the room. I don't think ANY other system at the show has been able to pull that off.
"Civil Wars - Another room where I don't feel like gouging out Jason's eyes for bringing this piece of music. Now THAT's a testament to the room's musicality :P
"Tom Waits - You know, for such a nicely balanced, somewhat warm and laid back presentation, they sure present old Tom with the appropriate gruffness. Here's the thing - in most systems you have to choose - do I want detail and grunt, or do I want warmth and musicality. Interestingly here, you get all the detail, soundstage and tone in a very musical presentation."
(Jason) "Ok outside of the sweet spot these sound good, but not mind blowing. In the sweet spot these are amongst the best I have heard in the show. I traded with Tyson for my tracks starting with the civil wars and there is a soooooo much more in the sweet spot. Great dynamics anywhere in the room, but imaging and soundstage that is quite breath taking and emotionality that is pretty heart stopping.
"Tom waits ohhhhhh wow. Just amazing. This feels like a real performance. I haven't heard such a focused soundstage at this show period. Absolutely phenomenal. Easily a contender for best in show."
Jason later posted that, in his opinion, we were tied with another speaker for best of show. I think Tyson had us tied for second.
Comments like "a lot of ambiance stretching WAAAAYYYYY back, way past the physical boundaries of the room" and "big spacious open sound... it actually expands beyond the physical confines of the room" are indications that the system was doing a good job of presenting the reverberant information that was on the recording intact, because those descriptions certainly do not correspond with the acoustic signature of a totally untreated hotel room.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 10/26/16 10/26/16 10/26/16 10/26/16
Thanks, Duke.
BW 800
BW 800
BW800
Excellent info and I have some research to do.
Gordon, if you're in town this fall as I think you are, you can come for a listen to Duke's speakers that I have here. Just give me a heads up.
Brian
So much music, so little time!
If we come in for Turkey Day, I'll reach out.
Go Cubs!
Thanks, I hope you can. Still attending games from time to time?
Go Cubs, indeed, although after last night it could be over soon.
Brian
So much music, so little time!
No Bears games this year. Schedules would not work.
I'd love to hear Dukes speakers. If you get back out our way stop buy. My Cary amp is back in action. I upgraded my DAC to a Multibit and installed a big Rythmic sub. A really improved experience. Love to have you over for a listen, drinks and chat.
Would you care to name (or allude to) one or two of the "relatively few" speakers that come close to accomplishing this feat?Of course, you need not mention any of your own designs. For instance, I can recall how VMPS (now defunct) used to offer rear-firing or top-firing "ambience tweeters" as an add-on option for use with some of their loudspeakers. What do you think of Brian Cheney's old idea?
Also, in a "two stream paradigm" design, are the high-frequencies the most important part of the spectrum to get right? Is there, in fact, a "most important part" of the spectrum?
Edits: 10/25/16
Dipoles positioned well out into the room meet the "Two Streams" criteria, as long as the spectral balance of the backwave is the same as that of the frontwave. Most omnis are going to have significant early sidewall interactions, unless the room is really big.I prefer to use controlled-pattern bipoles optimized for this application, for instance with the "rear" set of drivers firing from the floor up at the ceiling, which makes them more forgiving of placement near the "front" wall. Credit to James Romeyn for his "Late Ceiling Splash" idea, which I use with his permission. Credit also to Earl Geddes for something he taught me about the reverberant field.
In my opinion a speaker system's native off-axis response has to be taken into account if you want to add some additional drivers that would only cover part of the spectrum. Like if a speaker already has an off-axis flare at the lower end of the tweeter's range (where the tweeter's pattern is much wider than the midwoofer's), that would probably not be a good place to add a lot of additional reverberant energy. One reason why I shoot for fairly constant directivity with both sets of drivers is so that they "play nicely together", without putting too much reverberant energy into any part of the spectrum.
Rear-firing tweeters are usually added with the intention of correcting the reverberant field's relative level of upper frequency, to offset beaming of the front-firing tweeter. Imo this is definitely worth doing, but it isn't really a true "Two Streams" system even if you pull the speakers well out into the room.
I don't know how low in frequency you'd need to go with the rear-firing drivers. It probably depends somewhat on what the front woofer is doing, but I would guess you'd want to go down to at least 200 Hz. The "on axis" response of the rear-firing drivers would be of academic interest only; it is the power response that matters, along with enough directivity to keep sidelobes from becoming effectively "early reflections" in the midrange region.
Non-dipole speakers that meet the "Two Streams" criteria: Sonus Faber's expensive "Aida" uses what looks like a built-in rear-firing mini-monitor, and their "The Sonus Faber" model (now discontinued I think but it was their top of the line) had something similar that could be aimed to either side. ESP's new "Double Bass" speaker uses dual arrays firing in different directions. I think Definitive Technology still make bipolars. Imo the ESP "Double Bass" sounds absolutely magnificent. It's probably the best direct-radiator speaker I've heard, and is among the best speakers I've heard of any type.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 10/25/16 10/25/16 10/25/16 10/25/16 10/25/16
You say that the Prismas use "pattern control", which would seem to imply that their dispersion pattern is superior to that of more typical front-firing speakers. Or, is this simply another way of saying that the Prismas are optimized for placement near walls or corners?
Edits: 10/26/16
The rear-firing tweeter on the Prisma is compensation for the rectangular front horn's radiation pattern, which is narrower in the vertical plane than in the horizontal.
When I match up the horizontal radiation patterns of the woofer and horn in the crossover region, the reverberant field is "cheated" by the rectangular horn's narrower pattern in the vertical (which isn't necessarily all bad, as it reduces floor and ceiling interaction, and allows closer vertical center-to-center spacing of woofer and horn). The rear-firing tweeter adds just enough energy to the reverberant field to make up for the shortfall. The critical timing cues, as far as imaging goes, are all in the first-arrival sound.
Adding an essentially full-range rear-firing (or up-firing) section is a somewhat expensive proposition, both in drivers and in cabinetry. I've explored several driver options and settled on a part custom, part off-the-shelf solution which should allow me to do a Two Streams floor-stander in the same general price ballpark as the Prisma. It will have enough adjustability that against-the-wall placement will be feasible, and maybe even corner placement.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
OK, I'm guessing that your Prisma product page needs updating because the current specs make no mention of a "rear-firing tweeter"...Can you post pics of the new style Prisma speakers?
Edits: 10/27/16
You're right! Somehow the info on the rear-firing tweeter got dropped. Thanks for letting me know!
The "entry level Two Streams" speaker won't be a Prisma variant, it'll be its own thing. Soon as I have a production pair ready I'll take pictures, but I have a bit more prototyping to do first.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
I'm sure your new speaker will be at least as interesting as the Prisma is, or was.
IMO, your best looking speaker (so far) was the Jazz Module from several years ago. Any plans on going back to the circular horn shape?
I would prefer to reply to you privately, but your profile doesn't accept e-mails. Could you e-mail me?
Thanks!
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Email sent.
Good discussion so far. No offense to anyone, but 'audiophiles' are generally not knowledgeable in room acoustics nor the ear/brain hearing system. This often leads to inappropriate choices of loudspeakers for their listening environment. It's no wonder why "person A" says a speaker sounded excellent, and "person B" thinks they're so-so.As I've been preaching for 40 years, some speakers sound good in some rooms, and other speakers sound good in other rooms. On top of that, it also depends on the listener's preference: listening chair, or wide area coverage.
But an important fact which hasn't been mentioned in this thread is the fact that not all instruments radiate their sound in the same manner. A trumpet sounds very different at different angles from a flute or a timpani or a clarinet or the human voice. Yet, current technology limits us to reproducing all instruments via a single radiation pattern, which is not normal.
Lastly, someone here mentioned multi-channel systems. Back in 1975, I attempted to design a massively multi-channel system which would create a more believable and natural sound field. The big problems were installing and managing seven front channels and 30 or so ceiling, left, right and rear channels.
:)
Edits: 10/26/16
"But an important fact which hasn't been mentioned in this thread is the fact that not all instruments radiate their sound in the same manner. A trumpet sounds very different at different angles from a flute or a timpani or a clarinet or the human voice. Yet, current technology limits us to reproducing all instruments via a single radiation pattern, which is not normal."
Assuming the recording has captured a good representation of the reverberant energy of these different instruments, I think a good Two Streams setup has a better chance than most systems of delivering that reverberant energy in a convincing manner. This probably sounds counter-intuitive, as at first glance it looks like we're adding "more listening room" sound to the presentation, but I think the ear/brain system can do a better job of picking out the reverberant energy on the recording when it's presented this way, rather than only coming from the front of the speakers. See my post linked below, which offers some anecdotal evidence of this.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
They can do a reasonably good job, if the back wave is defused and the timing is right.
I used to have Snell B Minors, that had a rear firing tweeter. It did add a fair amount of air to the music but that's a little different.
Jack
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