Re: Re: Re: Since this is becoming a reference dipole thread...
It wouldn't be so important if the off-axis response of the speakers weren't so carefully controlled.
With a conventional speaker, the response is flat only in a very narrow window. When you're using a speaker with controlled directivity, the response is consistent across a wide window, as much as ninety degrees. Take a look at the polar response plots over on gedllee.com and you'll see what I'm talking about.
If you have an opportunity to hear them sometime, it's an eerie experience.
fcserei said:
It wouldn't be so important if the off-axis response of the speakers weren't so carefully controlled.
With a conventional speaker, the response is flat only in a very narrow window. When you're using a speaker with controlled directivity, the response is consistent across a wide window, as much as ninety degrees. Take a look at the polar response plots over on gedllee.com and you'll see what I'm talking about.
If you have an opportunity to hear them sometime, it's an eerie experience.
Re: Re: Re: Re: Since this is becoming a reference dipole thread...
I don't think it is the case.
In a real acoustic environment the listener is usually in the far field, getting the direct sound plus millions of early reflections and long reverb trail. Adding one more diffraction to this does not change anything basically.
OTOH in a small audiophile listening rooms with the stereo setup, you get too much of the direct sound and only a few - but compared to a concert hall- very loud early reflections and very short reverb trail. Adding a significant diffraction source here theoretically can be a more noticeable (?) change. The more controlled the speaker radiation pattern or deader the room, the more apparent the change can be.
This is not the only thing IMHO why room theatments or directivity controll alone is not the magic portion for realistic sound in stereo setup. Both actually change the perceived sound field at the listener's position to the worse: it will thin the otherwise too short reverb trail of the playback room, making it front stage heavy, audiophile-like presentation. Both will change the sound of "two speakers in a small, live room" to " two speakers in a small, not so live room", but they will never make an " orchestra in the Carnegie hall" sound.
I consider dipole speakers or "+" tweeters (and omnis too) in domestic environment as an attempt to restore some of the ambience missing in stereo, rather than a directivity controll measures. Too bad that the environment they use for that - the playback room - is a bad template.
Patrick Bateman said:
I don't think it is the case.
In a real acoustic environment the listener is usually in the far field, getting the direct sound plus millions of early reflections and long reverb trail. Adding one more diffraction to this does not change anything basically.
OTOH in a small audiophile listening rooms with the stereo setup, you get too much of the direct sound and only a few - but compared to a concert hall- very loud early reflections and very short reverb trail. Adding a significant diffraction source here theoretically can be a more noticeable (?) change. The more controlled the speaker radiation pattern or deader the room, the more apparent the change can be.
This is not the only thing IMHO why room theatments or directivity controll alone is not the magic portion for realistic sound in stereo setup. Both actually change the perceived sound field at the listener's position to the worse: it will thin the otherwise too short reverb trail of the playback room, making it front stage heavy, audiophile-like presentation. Both will change the sound of "two speakers in a small, live room" to " two speakers in a small, not so live room", but they will never make an " orchestra in the Carnegie hall" sound.
I consider dipole speakers or "+" tweeters (and omnis too) in domestic environment as an attempt to restore some of the ambience missing in stereo, rather than a directivity controll measures. Too bad that the environment they use for that - the playback room - is a bad template.
Re: Re: Re: Re: Re: Since this is becoming a reference dipole thread...
Reflections off of objects near the speaker change the frequency response. Even worse, these reflections confuse imaging by creating a phantom source. For instance, a reflection off an object one foot to the left of the speaker will create a phantom imaging source based on that reflection.
Are you CERTAIN that isn't a problem?
Are you arguing that "too much of the direct sound" is a BAD thing? So you're saying you would prefer to listen to the reflections off the walls more than what's coming from the speaker itself?
So you would argue that a speaker like the Linkwitz Orion is using dipole radiation for something other than "directivity control?"
fcserei said:
Reflections off of objects near the speaker change the frequency response. Even worse, these reflections confuse imaging by creating a phantom source. For instance, a reflection off an object one foot to the left of the speaker will create a phantom imaging source based on that reflection.
Are you CERTAIN that isn't a problem?
fcserei said:
Are you arguing that "too much of the direct sound" is a BAD thing? So you're saying you would prefer to listen to the reflections off the walls more than what's coming from the speaker itself?
fcserei said:
So you would argue that a speaker like the Linkwitz Orion is using dipole radiation for something other than "directivity control?"
Re: Re: Re: Re: Re: Re: Since this is becoming a reference dipole thread...
The strength of such reflections is the actual issue, and the purpose of an object being placed close to a speaker. Sometime it's just an unavoidable trade-off. Objects like plants has some relfection and some absorption. Additionally, as explained using the Huygens's Principle, the radiation range is diffused such that direct reflection engergy is greatly reduced compared with baffle endge diffraction. Only if you put an object in the path of high energy region in the controlled directivity will the object reflections become more significant. So I guess we really need to be specific as to where the object is.Patrick Bateman said:
Well, here's a real-world example, comparing the first-arrival energy vs all of the room reflections in the first second. Note the first-arrival SPL is 6~8 dB louder, despite the multiplicity of reflections in the room. Note also that with careful design, a conventional monopole can have a reasonably similar room-energy spectra compared to the direct-arrival sound.
I think it's easy to be misled by the "constant-directiy" argument. When the auditioner is sitting and listening to the hifi system (and the seat is somewhere in the 60-degree forward plane of radiation), they are not directly aware of the shape of the polar pattern.
What the listener hears are three things: the direct-arrival in the interval of 0 to 3 mSec, the summation of a large number of reflections from all directions in the 3 to 30 mSec interval, and if the acoustics are difficult enough (like a subway tunnel), discrete echoes in the 30 mSec and longer interval.
It's the ratio of direct to room-reflection spectra that matters, and how much they diverge from each other. The only way to directly audition the polar pattern is to do the obvious thing and walk around the loudspeaker, and walk close enough so the direct-arrival sound is much louder than the room energy.
I think of it in visual terms - direct vs indirect lighting, which look quite different in terms of illuminating the subject. I personally find the objective of minimizing room energy quite undesirable - the times I've tried it, putting loudspeakers outdoors didn't sound realistic at all, at least not in spatial terms. Maybe if the speakers are really awful PA speakers, it's an improvement, but for a high-quality speaker intended for reproduction of classical music, listening in a completely "dead" environment sounded grossly unnatural.
Now, if you seek the PA-system criteria of "intelligibility" for movie soundtracks and other Dolby Digital/MP3 degraded media, that's a completely different goal than musically satisfying reproduction of live music played with acoustical instruments in a symphony hall or recital room. If my primary goal was intelligibility, yes, I'd be looking at controlled (narrow) directivity systems too.
Speaking for myself, I find the goal of "intelligibility" fairly far down the list, and one that is met by nearly any half-decent hifi system with a half-decent (uncompressed) source. There were plenty of hifi systems in the Fifties that met this goal with LP's, prerecorded tape, and FM broadcasts. In subjective terms, clarity (the superset of intelligibility) and dynamic impact are important, but so are tonal realism and a reasonably convincing spatial illusion.
I think it's easy to be misled by the "constant-directiy" argument. When the auditioner is sitting and listening to the hifi system (and the seat is somewhere in the 60-degree forward plane of radiation), they are not directly aware of the shape of the polar pattern.
What the listener hears are three things: the direct-arrival in the interval of 0 to 3 mSec, the summation of a large number of reflections from all directions in the 3 to 30 mSec interval, and if the acoustics are difficult enough (like a subway tunnel), discrete echoes in the 30 mSec and longer interval.
It's the ratio of direct to room-reflection spectra that matters, and how much they diverge from each other. The only way to directly audition the polar pattern is to do the obvious thing and walk around the loudspeaker, and walk close enough so the direct-arrival sound is much louder than the room energy.
I think of it in visual terms - direct vs indirect lighting, which look quite different in terms of illuminating the subject. I personally find the objective of minimizing room energy quite undesirable - the times I've tried it, putting loudspeakers outdoors didn't sound realistic at all, at least not in spatial terms. Maybe if the speakers are really awful PA speakers, it's an improvement, but for a high-quality speaker intended for reproduction of classical music, listening in a completely "dead" environment sounded grossly unnatural.
Now, if you seek the PA-system criteria of "intelligibility" for movie soundtracks and other Dolby Digital/MP3 degraded media, that's a completely different goal than musically satisfying reproduction of live music played with acoustical instruments in a symphony hall or recital room. If my primary goal was intelligibility, yes, I'd be looking at controlled (narrow) directivity systems too.
Speaking for myself, I find the goal of "intelligibility" fairly far down the list, and one that is met by nearly any half-decent hifi system with a half-decent (uncompressed) source. There were plenty of hifi systems in the Fifties that met this goal with LP's, prerecorded tape, and FM broadcasts. In subjective terms, clarity (the superset of intelligibility) and dynamic impact are important, but so are tonal realism and a reasonably convincing spatial illusion.
Attachments
Going back to the quote about the houseplant, I don't find it all that outlandish. Putting anything close to a free-standing loudspeaker causes quite noticeable changes to the sound - especially if the reflector and/or absorber is close to one speaker but not to the other.
It's the distance of the offending reflection that's critical - anything within a metre of the front surface of the loudspeaker is going to have a fairly noticeable effect on image quality (as well as causing subtle colorations and loss of clarity). My own rule of thumb is to keep a one-metre sphere completely free of any reflections - as measured from the emissive surface of the tweeter and midrange.
On the other hand, houseplants make great diffusers at a larger distance (more than 2 meters) from the speaker, along with uneven surfaces like bookshelves filled with books of different sizes, as well as furniture of different sizes and coverings.
It's the distance of the offending reflection that's critical - anything within a metre of the front surface of the loudspeaker is going to have a fairly noticeable effect on image quality (as well as causing subtle colorations and loss of clarity). My own rule of thumb is to keep a one-metre sphere completely free of any reflections - as measured from the emissive surface of the tweeter and midrange.
On the other hand, houseplants make great diffusers at a larger distance (more than 2 meters) from the speaker, along with uneven surfaces like bookshelves filled with books of different sizes, as well as furniture of different sizes and coverings.
I wonder whether outdoor breeze and noise from trees effect this. Possibly background noise is also another factor that masks some of the lower level music and timbre. Too much envoronmental effect to really know that the cause of reduced fidelity. I think a 10M size anechoic chamber is a more realistic comparison.Lynn Olson said:
Ummm, it's more a matter of spatial perspective. Listening to loudspeakers outdoors sounds bone-dry, and narrow-directivity speakers share some of that dryness with an additional spatial distortion I can't quite pin down - the front-to-back distances are truncated, I think.
By contrast, loudspeakers with good first-arrival time dispersion that also illuminate the room with a well-balanced spectrum (that matches the direct-arrival spectra) typically have quite deep front-to-back perspectives (if the ancillary equipment has the ability to reproduce events in the -60 to -100 dB range without distortion).
My preferences on spatial perspectives are shaped by my initial work with SQ and QS quadraphonic systems, using a matched quartet of KEF 104ab loudspeakers - that's what I listened to the first time I heard the Audionics Shadow Vector prototype. Nowadays, the speaker layout would be called ITU standard, but that's the same layout I was using in 1973 - so it's not exactly original with the ITU. The CBS Labs guys were quite surprised when they heard the Shadow Vector at the 1975 Consumer Electronics Show in Chicago - they were still using the square layout back at the labs, and were amazed to hear stable, coherent imaging over a wide arc that covered most of the room.
The Big Two audio-review magazines have emphasized crisp primary images at the expense of overall spatial realism over the last twenty years. To me, this gives a cookie-cutter quality to the stereo (or surround) sound, and sounds quite unrealistic - sharp-edged images floating in a black, empty space, nothing like any acoustic I've ever heard in real life.
Thinking about my experiences at the last RMAF and earlier shows, I prefer a slightly warmer sound than the majority of modern audiophiles (if the bass is a little too rich, that's much more acceptable than thin and scrawny sound) and much more spacious and 3-dimensional sounding acoustic than modern audiophiles expect. Those of you who remember the rich, spacious, and lively sound of the first stereo systems of the late Fifties will know exactly what I'm talking about.
The transition to Class AB quasi-complementary discrete and op-amp transistor amplification (with 40~100 dB of feedback) severely flattened out the sound of stereo, and the transition to 44.1/16 PCM digital flattened out stereo even more. By the time you get to lossy-compressed digital, there's basically no stereo left at all, just a sort of disembodied multichannel AM radio sound. Take a good look at how the compression algorithms abuse the critical L-R difference signal - if the bit bin gets too full, the signal degrades to nothing more than loudness-steered mono, with no ambient information at all.
It's always entertaining to see the look of shock on a young guy's face when they hear an all-analog, all-tube system for the first time - I can't resist rubbing it in a little when I see that expression, and tell them that all stereo sounded that way for at least a decade - yes, in the movie theatres too, most dramatically for a road-show movie in 70mm discrete mag-track format. By comparison, modern cinema sound is a par with a disintegrating VW Rabbit with a $10,000 boom-car sound system.
By contrast, loudspeakers with good first-arrival time dispersion that also illuminate the room with a well-balanced spectrum (that matches the direct-arrival spectra) typically have quite deep front-to-back perspectives (if the ancillary equipment has the ability to reproduce events in the -60 to -100 dB range without distortion).
My preferences on spatial perspectives are shaped by my initial work with SQ and QS quadraphonic systems, using a matched quartet of KEF 104ab loudspeakers - that's what I listened to the first time I heard the Audionics Shadow Vector prototype. Nowadays, the speaker layout would be called ITU standard, but that's the same layout I was using in 1973 - so it's not exactly original with the ITU. The CBS Labs guys were quite surprised when they heard the Shadow Vector at the 1975 Consumer Electronics Show in Chicago - they were still using the square layout back at the labs, and were amazed to hear stable, coherent imaging over a wide arc that covered most of the room.
The Big Two audio-review magazines have emphasized crisp primary images at the expense of overall spatial realism over the last twenty years. To me, this gives a cookie-cutter quality to the stereo (or surround) sound, and sounds quite unrealistic - sharp-edged images floating in a black, empty space, nothing like any acoustic I've ever heard in real life.
Thinking about my experiences at the last RMAF and earlier shows, I prefer a slightly warmer sound than the majority of modern audiophiles (if the bass is a little too rich, that's much more acceptable than thin and scrawny sound) and much more spacious and 3-dimensional sounding acoustic than modern audiophiles expect. Those of you who remember the rich, spacious, and lively sound of the first stereo systems of the late Fifties will know exactly what I'm talking about.
The transition to Class AB quasi-complementary discrete and op-amp transistor amplification (with 40~100 dB of feedback) severely flattened out the sound of stereo, and the transition to 44.1/16 PCM digital flattened out stereo even more. By the time you get to lossy-compressed digital, there's basically no stereo left at all, just a sort of disembodied multichannel AM radio sound. Take a good look at how the compression algorithms abuse the critical L-R difference signal - if the bit bin gets too full, the signal degrades to nothing more than loudness-steered mono, with no ambient information at all.
It's always entertaining to see the look of shock on a young guy's face when they hear an all-analog, all-tube system for the first time - I can't resist rubbing it in a little when I see that expression, and tell them that all stereo sounded that way for at least a decade - yes, in the movie theatres too, most dramatically for a road-show movie in 70mm discrete mag-track format. By comparison, modern cinema sound is a par with a disintegrating VW Rabbit with a $10,000 boom-car sound system.
8NMB420 massive basket
It seems that it recently got new modern basket.
Pic and PDF on Eighteensound website now show something clearly different than pix in this thread :
http://www.hifi-forum.de/viewthread-104-9228.html
Old one :
New one :
SunRa said:
It seems that it recently got new modern basket.
Pic and PDF on Eighteensound website now show something clearly different than pix in this thread :
http://www.hifi-forum.de/viewthread-104-9228.html
Old one :
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
New one :
An externally hosted image should be here but it was not working when we last tested it.
Forgive me here Lynn, I'm not trying to bang heads but I seem to see a number of contradictions in some of your comments. You have stated over time that you don't follow the Floyd Tool school nor do you follow the arguments of constant directivity.
Recent examples are:
and then you state:
With regard to the first statement I don't recall anyone claiming that a listener would be aware of or need to know the polar response when sitting and listening in a normal position. Although I will say that dipole, omnidirectional and conventional speakers do all have significant differences in presentation which should make an educated listener able to identify each without walking around the speaker or room.. But the point is more the apparent contradiction of the first statement in combination with the second. The ratio of direct to reflected sound will be strongly dependent on the polar response, combined with the characteristics of the room, thus the argument for constant directivity goes very much hand in hand with uniformity of the ratio of direct to room-reflection spectra over the widest possible frequency range.
Then you go on to say that"
followed by:
Yet intelligibility is again highly related to correct first arrival time and the ratio of direct to reflected sound and its spectrum, which in turn is strongly dependent on a speaker’s directivity vs. frequency. Thus when you say you want accurate first arrival and uniformity of the dispersed spectrum relative to the direct spectrum it seems to me you are very much saying the intelligibility and uniform directivity are important. I would agree that for reproduction of music it may be desirable to increase the level of reflected sound above that which is typically considered acceptable to maximize intelligibility, but this is really a matter of listening distance and the acoustic environment. Certainly resolution and audibility of low level detail in musical reproduction is cloesly related to inteligibility. I also believe you have indicated you are more of the BBC shcool, however, intelligibility was an important consideration in the development of speakers such as the LS5/9 and LS3/5 series.
I'm a little confused by these apparent contradictions.
Recent examples are:
and then you state:
With regard to the first statement I don't recall anyone claiming that a listener would be aware of or need to know the polar response when sitting and listening in a normal position. Although I will say that dipole, omnidirectional and conventional speakers do all have significant differences in presentation which should make an educated listener able to identify each without walking around the speaker or room.. But the point is more the apparent contradiction of the first statement in combination with the second. The ratio of direct to reflected sound will be strongly dependent on the polar response, combined with the characteristics of the room, thus the argument for constant directivity goes very much hand in hand with uniformity of the ratio of direct to room-reflection spectra over the widest possible frequency range.
Then you go on to say that"
followed by:
Yet intelligibility is again highly related to correct first arrival time and the ratio of direct to reflected sound and its spectrum, which in turn is strongly dependent on a speaker’s directivity vs. frequency. Thus when you say you want accurate first arrival and uniformity of the dispersed spectrum relative to the direct spectrum it seems to me you are very much saying the intelligibility and uniform directivity are important. I would agree that for reproduction of music it may be desirable to increase the level of reflected sound above that which is typically considered acceptable to maximize intelligibility, but this is really a matter of listening distance and the acoustic environment. Certainly resolution and audibility of low level detail in musical reproduction is cloesly related to inteligibility. I also believe you have indicated you are more of the BBC shcool, however, intelligibility was an important consideration in the development of speakers such as the LS5/9 and LS3/5 series.
I'm a little confused by these apparent contradictions.
I was once asked by a friend to see if his room needed diffusers to help enchance the "big hall" sensation. I first told him it depended on what speakers he was using. When I visited his place and saw that his speakers had paper cones and soft dome drivers, it was a first indication that the speakers would nor reveal the low level reflections in recording, and thus whould sound more dry. Then in the same room we put up my little speakers, and immediately we all realized how critical speaker drivers are. It was clear that the little full range speakers delivered much better image and spacial impression. The only thing that the little speakers could not match his original speakers was the low frequency SPL, especially the puch. It is possible to use room effects to try to recreate the spacial impression. But it seems the source cause of dryness is lack of capability to reproduce detail, this is one reason why Ted Jordan started out on metal based drivers. Since no driver is the best performer at low and high level listening, we just need to choose the most appropriate driver for our specific application.Lynn Olson said:
CS2w
Gentlemen,
I fail to find any comments about the Emerald Physics CS2w "Bass Generators". Were they absent from any demonstrations?
For those of us that don't want sub woofers, the concept would seem to be great for WAF & speaker arrangement in general.
Are back-to-back open baffle woofers like these worth trying?
dobias
Gentlemen,
I fail to find any comments about the Emerald Physics CS2w "Bass Generators". Were they absent from any demonstrations?
For those of us that don't want sub woofers, the concept would seem to be great for WAF & speaker arrangement in general.
Are back-to-back open baffle woofers like these worth trying?
dobias
Sorry for warming up such old stuff, but there was one thing quite early in the thread I wanted to correct:
It was said that domes can be ruled out for a high sensitivity project, but that this company prefers the 97/98dB Supravox tweeter in a low sensitivity speaker of that price makes me think...
http://www.polymeraudio.com/
It was said that domes can be ruled out for a high sensitivity project, but that this company prefers the 97/98dB Supravox tweeter in a low sensitivity speaker of that price makes me think...
http://www.polymeraudio.com/
Marketing Department strikes again...
Wow, the Marketing Department at Polymer logic sure did get out-of-hand on this one !!!
200 dB total range
This is the most severe case of "SPL smoothing by range expansion" that I have ever seen!
Here is the Frequency Response plot with a REAL axis range:
The +/- 3 dB through 100 - 300 - 1000 Hz doesn't look too good. If this is real (not a measurment artifact) they are definitely not voiced to my taste
Edward
Wow, the Marketing Department at Polymer logic sure did get out-of-hand on this one !!!
200 dB total range
This is the most severe case of "SPL smoothing by range expansion" that I have ever seen!Here is the Frequency Response plot with a REAL axis range:
The +/- 3 dB through 100 - 300 - 1000 Hz doesn't look too good. If this is real (not a measurment artifact) they are definitely not voiced to my taste
Edward
I would like to point everyone to what's going on over at Magnetar's thread.
Things have taken a very interesting turn, discussing both the B&C 6PEV13 and the 18Sound 6ND410 in a 300 Hz horn, paired with a 5X 10" woofer dipole array.
By getting the horn out of the way around 3 kHz, that sidesteps a lot of the typical "horn sound" when a horn is asked to cover the range from 1.5 to 15 kHz, as well as a lot of phase-plug troubles (non-uniform wavefront entering the horn) when compression drivers are used. Another appealing feature is the effective radiating area of the horn is similar to the radiating area of the open-baffle drivers - I can see using the 300 Hz horn with a 4X array of 12" drivers, for example.
Hmm - a quad array of mix-n-match Alnico+ceramic 12" Tone Tubby's, a 300 Hz horn with the 6ND410, and a double-high RAAL tweeter (which delivers an additional 2.5 dB at distances greater than 2 meters). Let's see now, no bi-amping required, efficiency somewhere around 103 dB/metre, a pretty simple 3-way system, hmmm .......
Things have taken a very interesting turn, discussing both the B&C 6PEV13 and the 18Sound 6ND410 in a 300 Hz horn, paired with a 5X 10" woofer dipole array.
By getting the horn out of the way around 3 kHz, that sidesteps a lot of the typical "horn sound" when a horn is asked to cover the range from 1.5 to 15 kHz, as well as a lot of phase-plug troubles (non-uniform wavefront entering the horn) when compression drivers are used. Another appealing feature is the effective radiating area of the horn is similar to the radiating area of the open-baffle drivers - I can see using the 300 Hz horn with a 4X array of 12" drivers, for example.
Hmm - a quad array of mix-n-match Alnico+ceramic 12" Tone Tubby's, a 300 Hz horn with the 6ND410, and a double-high RAAL tweeter (which delivers an additional 2.5 dB at distances greater than 2 meters). Let's see now, no bi-amping required, efficiency somewhere around 103 dB/metre, a pretty simple 3-way system, hmmm .......
It's been a very interesting thread, and I think Mike may have hit on something excellent here.Lynn Olson said:
Taking slightly off track, and from your ealier comment in post 2557 re the ITU standard for multi-channel, if you were to implement the above 4x12" front, do you think it would be feasible to have the same MF+HF on the rears, but a 2x12". The levels are usually much lower on rears and usually for shorter duration. Just trying to think how to integrate it all into the room without it being too space consuming. It would be multiamped, at least with a different amp on the LF drivers so levels could be set accurately for the different F and R.
The temptation to cheat on the rear and center speakers would be hard to resist - I'd even consider a single 12" driver, and just highpass the thing somewhere around 100~120 Hz. Where the phase matching really matters is at higher frequencies, 500 Hz on up. This is where identical polar patterns and phase and frequency response are mandatory.