Jaco Pastorius said:
There are threshold level for reflections to become audible. See Olive/Toole.
Yes, every speaker interacts with the room. But the interesting thing is how they interact with the room. Open baffles create strong early first reflections. That is not desireable for acurate sound reproduction. Maybe it's desireable in combination with some recordings to create an illusion of spaciousness found in concert halls. But that's a dead end if you want to use your speakers for other type of recordings too. Better solutions exist.
And if you have ever listened in an anechoic chamber or with ear phones you know how inadequate the ambience cues on the recording are in recreating a pleasing presentation.
The difference between a dipole and a box speaker with the same on axis response, when placed in a listening room, is predominately the differences in the way each sets up the reverberant sound field. Placed outside, or in an anechoic chamber the major cause of differences will be due to differences in the frequency response/time response of the direct sound.
The difference between a dipole and a box speaker with the same on axis response, when placed in a listening room, is predominately the differences in the way each sets up the reverberant sound field. Placed outside, or in an anechoic chamber the major cause of differences will be due to differences in the frequency response/time response of the direct sound.
Perception of reflections depends from frequency, delay time and waveform too…
Remember that a pseudodipole speaker approximating the point source for “the same on-axis sound pressure level as from a monopole needs to radiate only 1/3rd of the monopole's power into the room.” (S.L.)
Really don’t now what you’re talking about..
John
I agree, if by "reverberant field" you are including the early reflections. I think that the big difference are to be found in the polar response and that the polar response is a huge factor - more important IMO than the axial response.
Dead rooms aren't very satisfying, while lively rooms can be. But a live room adds its own "acoustic" to the playback. Thus the "you are there" illusion can never be as great as the "they are here" one since the "they are here" relys on the local acoustic. As Markus has said, the "you are there" illusion requires multichannel to even get close.
I agree, if by "reverberant field" you are including the early reflections. I think that the big difference are to be found in the polar response and that the polar response is a huge factor - more important IMO than the axial response.
Dead rooms aren't very satisfying, while lively rooms can be. But a live room adds its own "acoustic" to the playback. Thus the "you are there" illusion can never be as great as the "they are here" one since the "they are here" relys on the local acoustic. As Markus has said, the "you are there" illusion requires multichannel to even get close.
gedlee said:
It would seem to follow that polar response wouldn't matter much in a completely dead room, except to influence off axis listening.
Interesting new building almost finished near me - the new UC San Diego music center. One element is a "black box" auditorium, which is designed to be very "dry", as they call it. It's kinda strange to be inside of it, as you get no sense of dimension. There will be 35 or so speaker systems set up throughout the room, so that any variety of illusions can be created, some in ways not yet contemplated - but that's the whole point. Joint programs and degrees already exist between the music department and computer science. Good fun to be had by all.
Sheldon
Jaco, to be exact, the perception of reflections depend on kind of signal, arrival time, level and incidence angle. Not on spectrum.
Have you seen real world polar response data of the Orion? Are you sure it radiates "only 1/3rd of the monopole's power into the room"?
How do you think the sound radiated from the back of an OB interacts with a room?
Have you seen real world polar response data of the Orion? Are you sure it radiates "only 1/3rd of the monopole's power into the room"?
How do you think the sound radiated from the back of an OB interacts with a room?
poptart said:
Hy
in something like a symmetrical donut like a standing 8... the first Manger
back to back was shown beginning 70's Hifi show Germany Duesseldorf.
In a spiral baffele somewhere on the Manger page Mangers also does exist.
The idea with a double symmetrical donut seems very promising to me
could be made with a Jordan maybe to, quite fullrange why not.
Marcus you’re in right I forgot incidence angle but I’ve never talked about spectrum… Probably, with my poor English, I could be misunderstood.
Orion obviously hasn’t a perfect point source dipolar radiation pattern and, obviously, is very hard to find a perfect monopole radiation pattern speaker. Linkitz data are “theoretical”. No one could deny that they don’t radiate the same total power.
box speaker radiates (partially) from the back too with a great difference: no CD…
Orion obviously hasn’t a perfect point source dipolar radiation pattern and, obviously, is very hard to find a perfect monopole radiation pattern speaker. Linkitz data are “theoretical”. No one could deny that they don’t radiate the same total power.
box speaker radiates (partially) from the back too with a great difference: no CD…
The power response for a dipole created by two omni sources has a strange behavior as shown in this figure
The red line represents the unequalized dipole. Green is when the dipole is equalized for flat response. The dipole has 4.8dB less radiated power at low frequency but as we approach the dipole peak the power starts to increase and ultimately, above the dipole peak the dipole acts as two uncorrelated sources with result that the radiated power is actually 3dB greater than a single omni source.
When we include directionality of the sources, the power looks like
which is why it is very important of where the crossover to the tweeter is in a dipole and whether or not a rear tweeter should be used.
This is representative (not exactly) of what the power response of a driver mounted on an open baffle would look like.
Earl,
"I agree, if by "reverberant field" you are including the early reflections. I think that the big differences are to be found in the polar response and that the polar response is a huge factor - more important IMO than the axial response."
Agreed. This is exactly what I was saying using different words. Placing the speaker outside or in an anechoic room takes the polar response out of the picture and we only hear the direct sound. In a room it is the polar response that sets up how the room reverberant field is excited by the speaker. We extract location from the direct sound and a sense of spaciousness form the reverberant field. But note that when I say direction I mean the location of a sound source. This is not the same as how two stereo sources set up a false illusion of a 3-d performance.
Dead rooms just don't do the trick with any speaker because, as I said, the ambience cues on the recording are inadequate in recreating a pleasing presentation. In such a case we become only an observer to the event rather than a participant. We don't want to hear what is going on at the part next door. We want to be at the party. But still there are big differences to the way different individuals perceive sound. For example, what I hear at a concert will be very different if I am in the 2nd balcony or front row center, which is still different from what the first violinist hears or what Eric Caption hears on stage. Which is right? Which should I strive to recreate in my listening room? Which type of speaker will suit each situation best? It is ultimately a matter of taste.
The red line represents the unequalized dipole. Green is when the dipole is equalized for flat response. The dipole has 4.8dB less radiated power at low frequency but as we approach the dipole peak the power starts to increase and ultimately, above the dipole peak the dipole acts as two uncorrelated sources with result that the radiated power is actually 3dB greater than a single omni source.
When we include directionality of the sources, the power looks like
which is why it is very important of where the crossover to the tweeter is in a dipole and whether or not a rear tweeter should be used.
This is representative (not exactly) of what the power response of a driver mounted on an open baffle would look like.
Earl,
"I agree, if by "reverberant field" you are including the early reflections. I think that the big differences are to be found in the polar response and that the polar response is a huge factor - more important IMO than the axial response."
Agreed. This is exactly what I was saying using different words. Placing the speaker outside or in an anechoic room takes the polar response out of the picture and we only hear the direct sound. In a room it is the polar response that sets up how the room reverberant field is excited by the speaker. We extract location from the direct sound and a sense of spaciousness form the reverberant field. But note that when I say direction I mean the location of a sound source. This is not the same as how two stereo sources set up a false illusion of a 3-d performance.
Dead rooms just don't do the trick with any speaker because, as I said, the ambience cues on the recording are inadequate in recreating a pleasing presentation. In such a case we become only an observer to the event rather than a participant. We don't want to hear what is going on at the part next door. We want to be at the party. But still there are big differences to the way different individuals perceive sound. For example, what I hear at a concert will be very different if I am in the 2nd balcony or front row center, which is still different from what the first violinist hears or what Eric Caption hears on stage. Which is right? Which should I strive to recreate in my listening room? Which type of speaker will suit each situation best? It is ultimately a matter of taste.
régine's,
It was the first thing i thought of when i saw open baffle, "why is it always flat?" but at the time I didn't have enough knowledge to design something like that. With the tools Linkwitz and John K have given us for dipoles and the lessons Earl has given us about waveguides I think I understand what it would do now, but I don't personally have a need for such a thing.
To be more clear the cross section would be shaped like a tear drop... short, fat teardrop above and below the driver, slightly more elongated teardrop by the time you reach the sides.
It was the first thing i thought of when i saw open baffle, "why is it always flat?" but at the time I didn't have enough knowledge to design something like that. With the tools Linkwitz and John K have given us for dipoles and the lessons Earl has given us about waveguides I think I understand what it would do now, but I don't personally have a need for such a thing.
To be more clear the cross section would be shaped like a tear drop... short, fat teardrop above and below the driver, slightly more elongated teardrop by the time you reach the sides.
John
When viewed in that context yes.
But ultimately all "stereo" recordings are mixed in two channel situations and the decisions about the "preferences" that you mentioned are made by the engineers. In that case there is a clear reference, what the engineers intended, which is completely unambiguous.
When viewed in that context yes.
But ultimately all "stereo" recordings are mixed in two channel situations and the decisions about the "preferences" that you mentioned are made by the engineers. In that case there is a clear reference, what the engineers intended, which is completely unambiguous.
Surprise, but I totally agree with Earl. It's one of the greatest misconceptions to alter the reproduction devices to have a "more realistic" perception. Nobody knows how a recording was recorded and mixed.
Not only from the direct sound but from all coherent sound sources arriving within 1 (or 1.5) ms at the listening position. Otherwise stereo wouldn't work.
Best, Markus
Not only from the direct sound but from all coherent sound sources arriving within 1 (or 1.5) ms at the listening position. Otherwise stereo wouldn't work.
Best, Markus
gedlee said:
But this is just a circular argument because if we want to hear what the engineer put down we need to also listen through his monitoring system, in his studio with his ears at the levels he set...
No, ultimately home audio is about nothing more that what the listener preceives as most satisifying.
Sorry John, this is where I don't agree. There is a reference and that is what the artists (producers, etc.) intended. The monitor situation makes it a little more complicated, yes, but it doesn't make the whole argument wrong. You should read Tooles book on this. He does a good job of explaining it, but then he takes about ten pages to do so. I have a paragraph.
after the all holy "engineer's mix" is done the whole thing goes to another place in another room, another set of speakers and another set of ears for mastering through another barrage of eq and dynamics manipulation software. The original artists are not present for this. Sometimes they're not present for the first round either. Where's your absolute reference now?
A few months ago I saw a post in one of the mixing/mastering forums from the guy who mastered Metallica's last album. (the latest and most odious bullet to be fired in the loudness war). His name isn't even on the liner notes and it's pretty easy to hear why. He says the mix arrived in his hands already brick wall clipped so there was little he could do, but often the reverse happens. The mix is to the band's liking then the mastering guy crushes it. Or the band or label themselves ask for that to happen. So your all powerful engineer really doesn't have as much control as Markus and Earl wish he did. I understand your discomfort with this, without an absolute reference everything else we build is thrown into question but welcome to the real world. Now be flexible and engineer things knowing there's flex in the foundations instead of assuming absolutes
A few months ago I saw a post in one of the mixing/mastering forums from the guy who mastered Metallica's last album. (the latest and most odious bullet to be fired in the loudness war). His name isn't even on the liner notes and it's pretty easy to hear why. He says the mix arrived in his hands already brick wall clipped so there was little he could do, but often the reverse happens. The mix is to the band's liking then the mastering guy crushes it. Or the band or label themselves ask for that to happen. So your all powerful engineer really doesn't have as much control as Markus and Earl wish he did. I understand your discomfort with this, without an absolute reference everything else we build is thrown into question but welcome to the real world. Now be flexible and engineer things knowing there's flex in the foundations instead of assuming absolutes
gedlee said:
Recording and mixing music is a very subjective process, and I think most people overestimate the taste, skill and degree of intention of the myriad of people involved in the recording process. Hell, we can't even agree how to reproduce the recording, which is just one part of what they have to do. Know what the artist/engineer/producer/masterer intended is about as likely as knowing what they were thinking, consciously and subconsciously, the whole time they were working on the recording. I think we need another 'target', which is why I consider live performance the most valid reference. But since virtually none of the recordings we listen to, we were also present at, I agree with Johns statement:
john k... said:
(btw, Earl, were you referencing Toole's 'Sound Reproduction' book?)
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