markus76 said:
As I said, "true" difusivity in a theoretical sense is never possible. But just as true "theoretically" is that there is no reason that a small room cannot be difuse. In a practical sense a large room will "tend" to be "more difuse" than a small room simply by the fact that its reverberation time will be longer, but this is a general characteristic and not an absolute one as you stated. I could make rooms such that the smaller one was more difuse than the larger one. You simply cannot make blanket statements.
So why did Gover find that the contrary is true? How to make a living room more diffuse? What amount of diffusivity is desirable? And how do you measure that?
I didn't read the paper so I don't know. In room acoustics I was taught that the more difuse the reverberant field the better. But others believe that its realy the lateral reflections that count, which imples that difusivity isn't really that important at all. I doubt that there are answers to your other questions any more than there are absolutes to the surround issue. This is why I avoided talking about it - there aren't any real answers, only a "difuse" set of beliefs.
The Dolby manual was not that insistant on monopole surrounds, in fact all they said was that the mains and surrounds should "ideally" be the same (but this, to me, seems totally impractical in a home). If the mains were dipoles then the surounds should be dipoles!? Dolby and THX don't always agree. But in any THX mixing stage you will likely find dipole surrounds.
The Dolby manual was not that insistant on monopole surrounds, in fact all they said was that the mains and surrounds should "ideally" be the same (but this, to me, seems totally impractical in a home). If the mains were dipoles then the surounds should be dipoles!? Dolby and THX don't always agree. But in any THX mixing stage you will likely find dipole surrounds.
gedlee said:
You definitely should read it - a huge part of Tooles argumentation is based on it.
It's a proven fact in psychoacoustics that lateral reflections lead to spaciousness and envelopment. So I don't understand why you advocate for dipoles when direct speakers can deliver lateral signals more efficiently.
I don't know any manufacturer of dipole speakers for cinematic monitoring purposes. So I think Dolby is pretty clear on what a mixing setup should look like.
markus76 said:
I don't really "advocate" anything as much as I adapt what the experts in this area suggest. I am not the expert on surrounds. And as I have been saying, I don't think that surrounds are necessarily for adding spaciousness and envelopment - thats the music playback position NOT the film position.
"direct speakers can deliver lateral signals more efficiently." I'm not sure this is the case either, as I have also said. Only in the first few ms would this necessarily be true, but after that the rooms configuration will dominate the sources directivity.
Markus, you are getting way too tied up in surrounds as main effects like the front speakers. I don't see it that way and, again, there is no concrete theory here so there isn't a right or wrong. I have experimented with both types of surrounds and I prefer the dipoles because the lack of a direct sound component makes them difficult to impossible to localize on - which is what I want.
Markus. I can't remember over the last 20 pgs of posts how you intend to use the Nathans. If they are being relegated to sides or rears in a surround system, that's fine. If, the Nathans are to be the mains, then I believe this discussion has wandered off topic - once again.
Its an artificial thing from the dub theater steering joysticks and the multitudes of DSPs, to the field recreation around your couch. Has to be enjoyable and not that evident, that is all IMHO. I am with Earl on that one. I.e. whatever works to make it nice and clueless.
Err, you wrote a book on surround!? And of course is the goal of a film mix to envelop the audience.
Exactly that's why I would tend to use direct radiating speakers. You said that there are no numbers or measurements that indicate the right amount of diffusivity. Furthermore the behavior of dipoles in normal living rooms is unpredictable - there wouldn't be even a few controlled first ms. So it's reasonable to use speakers that deliver the most constant results across different livingrooms.
I still don't understand why a direct radiating surround speaker should be more localizeable when it's just used for playback of discrete reflections generated with an effects processor by a mixing engineer. When there is only one surround channel then there would be decorrelation problems a dipole can solve, but with 2 and more discrete effects channels?
markus76 said:
I'm not even sure that I mention surround in my Home Theater book, but I certainly don't dwell on it in any detail at all.
But thats exactly my point, only for musical performances (which I am NOT trying to do, I never use the surrounds for music playback) would this be the case. For film this is not true at all as the surround presents "effects" that take place around the listener, like gunshots, or environmental ambiance (jungle noises, etc.) that are anything but "discrete reflections". The idea is to give the illusion of something happening at a location that is not within the films viewport. Its not important that these effects be localized at all, not even desirable IMO, only that one has this impression of something happening "over there someplace". Its not about room reflections at all.
No artificial reverberation in the surround sound channels?
P.S. Sorry for confusing "Home Theater" with "Multichannel" 🙂
He also came up with Timbre Matching to make surrounds sound more like the fronts, which seems ill-founded as it nullifies the HF loss that our ears give for sounds behind us.
I do agree that surround reproduction is a matter of taste and can understand the willingness to sacrifice those few localized effects for the much more pervasive ambient effects, but personally I'm shooting for closer to the middle.
I do agree that surround reproduction is a matter of taste and can understand the willingness to sacrifice those few localized effects for the much more pervasive ambient effects, but personally I'm shooting for closer to the middle.
When i referred to Dipoles as a recomendation from Dolby, it wasn't for production, it was for reproduction, as in the home theater, this is what their site and site documentation had shown. The rest of the recommendations are THX or Holman really, but given the close work they had with Dolby, I would expect the consistent recommendations between those groups.
You do understand that Mastering and mixing aren't the same thing right? Initial mixing is often done with very different quality speakers than final mastering of the mix. Typically THX Pm3 monitors are used for the mixing, but most mastering is done with very different speakers. Look at all the major film studios and think how many of them have screening rooms, usually multiples, set up with speaker arrays of all types.
Edit:I relooked at Dolby and found that the document I grabbed must have been older, as everything else for playback indicates identical speakers. It's really not clear, they don't address the dipole bipole thing anymore at all, just always shows a picture of a monopole, and refers to 5 identical speakers. THX and Holman seem to be the holdouts here, but also seem to be the industry standards.
While M&K is now out of business, they did make dipole surrounds for mixing use, but thats the only company I knew of. The Dipoles were typically used for final mastering in the screening rooms (Thats where I have seen them), not in the mixing rooms. My tours often involve a chance to see a screening, and usually the engineers use this screening to test their mixes. The comments I hear (This is consistent with Holman's book and lectures by the way) is that final mastering must be done in an environment reminiscent of where it will be played. Initial mixing is to get the levels right, basic equalization, fades, etc, all the detail work. The mastering is done to put the final polish on the sound track, and is typically done with multiple screenings in an actual theater, with notes taken throughout, and changes made from there (If the screening room doesn't allow changes to be tried on the spot, some I have seen do). Larger theaters are used when mixing for the actual cinema, but our little rooms aren't cinemas, and movies are remixed when put onto dvd. Often the screening here is done in smaller screening rooms with normal home theater speakers, using dipole surrounds. This is my experience, this is Holman's recomendation, Dolby's recomendation, etc.
You do understand that Mastering and mixing aren't the same thing right? Initial mixing is often done with very different quality speakers than final mastering of the mix. Typically THX Pm3 monitors are used for the mixing, but most mastering is done with very different speakers. Look at all the major film studios and think how many of them have screening rooms, usually multiples, set up with speaker arrays of all types.
Edit:I relooked at Dolby and found that the document I grabbed must have been older, as everything else for playback indicates identical speakers. It's really not clear, they don't address the dipole bipole thing anymore at all, just always shows a picture of a monopole, and refers to 5 identical speakers. THX and Holman seem to be the holdouts here, but also seem to be the industry standards.
While M&K is now out of business, they did make dipole surrounds for mixing use, but thats the only company I knew of. The Dipoles were typically used for final mastering in the screening rooms (Thats where I have seen them), not in the mixing rooms. My tours often involve a chance to see a screening, and usually the engineers use this screening to test their mixes. The comments I hear (This is consistent with Holman's book and lectures by the way) is that final mastering must be done in an environment reminiscent of where it will be played. Initial mixing is to get the levels right, basic equalization, fades, etc, all the detail work. The mastering is done to put the final polish on the sound track, and is typically done with multiple screenings in an actual theater, with notes taken throughout, and changes made from there (If the screening room doesn't allow changes to be tried on the spot, some I have seen do). Larger theaters are used when mixing for the actual cinema, but our little rooms aren't cinemas, and movies are remixed when put onto dvd. Often the screening here is done in smaller screening rooms with normal home theater speakers, using dipole surrounds. This is my experience, this is Holman's recomendation, Dolby's recomendation, etc.
markus76 said:
My hope with downloads is that they are embraced in high end home theaters and the technology keeps pace. So far that is actually the case by and large. Netflix is one of the few streaming serviced offered, I have it, I use it for things like tv shows, but otherwise find it a pretty bad "download" format. The Sony and Xbox networks are far better, with very decent quality (all things considered) and offering actual surround encoding. Again, I'm hoping that as internet bandwidth increases, these technologies will keep pace, and we might actually see Bluray quality (or similar) in a ten minute download. However, as I understand it, we are hitting an infrastructure brick wall, and its likely to be quite some time before we see that problem fixed, so I see this as a big barrier in downloaded media going fully mainstream and completely taking over for physical media. I mean, keep in mind that downloaded movies is less than .1% of total movies right now, and music is still only around 10-12% a year, its growing, but we wont see it as the mainstream format for a good 5-10 years, if not more.
Time is up for Dolby Pro Logic 🙂 That's why we don't need dipoles anymore. Let's move on to speakers that match the requirements of discrete surround channels.
Holman left Lucasfilm, right?
Matt
Agreed.
I have Netflix and use the download a lot, but not for a movie that I really want to see, the quality is just not good enough. I have had a try of the NBC HD downloads (Heros and Office) and they are too buggy at this point - still in Beta and not yet working acceptably. I agree that streaming downloads of HD over the internet are some years away. I'm not going to get rid of my Blue-ray player just yet!
A big part of my preference for dipoles as surrounds has to do with my very small room (a typical sized Home Theater). A monopole speaker is only be about 3 feet away from some listeners and this is just too close, its basically in the nearfield of a monopole. So some changes from standard loudspeaker design has to be made in spaces like mine. I've experimented and found the dipole to work best in my situation because the speakers are playing right into your ear. The surround effects from the dipoles sound like they are much farther away than the source really is and that, to me, is a very good thing.
Holman hasn't been with Lucas for almost a decade, he's a Prof at UCLA in the Film Department, but he is still IMO, the expert on film audio. Until he changes his position I won't be changing mine.
Markus - you need to actually setup some surround systems - look at the expense of seven identical speakers of the quality of a Nathan, the difficulty in positioning and mounting them, and finally playing them right into your ears. You'll find this approach untenable, just like I have. But then you could go get Bose cubes - those are all identical, full range, and very easy to mount! 🙂
Agreed.
I have Netflix and use the download a lot, but not for a movie that I really want to see, the quality is just not good enough. I have had a try of the NBC HD downloads (Heros and Office) and they are too buggy at this point - still in Beta and not yet working acceptably. I agree that streaming downloads of HD over the internet are some years away. I'm not going to get rid of my Blue-ray player just yet!
A big part of my preference for dipoles as surrounds has to do with my very small room (a typical sized Home Theater). A monopole speaker is only be about 3 feet away from some listeners and this is just too close, its basically in the nearfield of a monopole. So some changes from standard loudspeaker design has to be made in spaces like mine. I've experimented and found the dipole to work best in my situation because the speakers are playing right into your ear. The surround effects from the dipoles sound like they are much farther away than the source really is and that, to me, is a very good thing.
Holman hasn't been with Lucas for almost a decade, he's a Prof at UCLA in the Film Department, but he is still IMO, the expert on film audio. Until he changes his position I won't be changing mine.
Markus - you need to actually setup some surround systems - look at the expense of seven identical speakers of the quality of a Nathan, the difficulty in positioning and mounting them, and finally playing them right into your ears. You'll find this approach untenable, just like I have. But then you could go get Bose cubes - those are all identical, full range, and very easy to mount! 🙂
They do big identical monitors in dub theaters, but those are huge spaces compared to normal home theaters.
Checked the THX website what surround speakers are "THX approved" - looks like there are no dipoles at all in their listing:
http://www.thx.com/products/professional/index.html?f=s
http://www.thx.com/products/professional/index.html?f=s
Of late in addition to his professorship at USC Holman has been acting as chief scientist for http://www.audyssey.com/
They've got a 'whole room' treatment thing going on.
They've got a 'whole room' treatment thing going on.
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