Interesting. I didn't know there was such a thing as phantom mode. I'll certainly try it, thanks.
But for the future I'm moving on to a front-horn stereo system with a great front-horn center speaker for the summed channels...or the center channel if I can get it decoded without entering the digital twilight zone....
Vincent Brient in France has me absolutely psyched on DIY'ing these puppies: http://vincent.brient.free.fr/round_horns.htm
except I want to leave the midrange and bass OB'd, but front-horned in front! What fun.
Best, Charlie
pos said:
Not with a toed-in summa setup
Phantom sources will shift when you move horizontally anyway. This kind of setup (I think it was Bauer that proposed that kind of setup decades ago) minimizes shift but there is still a shift. It depends on how much shift one tolerates. I don't tolerate any shift at all.
I don't think that a phantom center is the ideal, a dedicated center channel is ideal, but unless you can do the center channel right, the phantom is the better choice.
If you use two speakers to do a center phantom, then there will be a great deal of horizontal lobing and the image will degrade off center. This does not occur with the real center. But, as mentioned, if the center speaker is not the same as the left and right (and God forbid that it is worse) then the situation is even worse because of the disconnect between the center and left and right.
So, based on lots of experience, either use an identical center speaker to "GOOD" left and rights - which virtually dictates an acoustic screen - or use phantom mode.
If you can hear the surrounds then they are too loud.
Better to have two good speakers and cheap surrounds, than five cheap speakers as are always sold in the "packaged" systems.
If you use two speakers to do a center phantom, then there will be a great deal of horizontal lobing and the image will degrade off center. This does not occur with the real center. But, as mentioned, if the center speaker is not the same as the left and right (and God forbid that it is worse) then the situation is even worse because of the disconnect between the center and left and right.
So, based on lots of experience, either use an identical center speaker to "GOOD" left and rights - which virtually dictates an acoustic screen - or use phantom mode.
If you can hear the surrounds then they are too loud.
Better to have two good speakers and cheap surrounds, than five cheap speakers as are always sold in the "packaged" systems.
If I recall correctly from Toole and/or Holman, phantom centers are perceived as more distant and spacious in terms of their sound compared to an actual center, so many single listeners will prefer them for these reasons. There is an interference dip at around 2 KHz, as well, of course.
Dedicated center channels will sound brighter, closer, and narrower (ASW) by contrast for most listeners. There can be an element of cognitive mismatch for larger screens. Because of practical issues regarding where the speakers can be located, many surround setups will introduce adjacent boundary effects (television or floor) when it comes to the front channel and thus colorations. Obviously, there is the issue of nonidentical front channels that comprise many surround systems. Even acoustic screens are really translucent, rather than transparent, when it comes to sound.
You already know all of this, so I don't know what other advantages you might be wondering about.
Dedicated center channels will sound brighter, closer, and narrower (ASW) by contrast for most listeners. There can be an element of cognitive mismatch for larger screens. Because of practical issues regarding where the speakers can be located, many surround setups will introduce adjacent boundary effects (television or floor) when it comes to the front channel and thus colorations. Obviously, there is the issue of nonidentical front channels that comprise many surround systems. Even acoustic screens are really translucent, rather than transparent, when it comes to sound.
You already know all of this, so I don't know what other advantages you might be wondering about.
Why would a phantom center have an interference dip at 2 kHz? At least not on the center axis. Off axis there should be lobing of the sources and periodic dips at different angular locations. But both sources should add in phase on the center-line.
The right screen is actually very transparent, but not the commercial ones, thats for sure. And if all three speakers are behind the screen then the effect is at least constant.
The right screen is actually very transparent, but not the commercial ones, thats for sure. And if all three speakers are behind the screen then the effect is at least constant.
youngho, multichannel presentations are mixed using a center speaker and there is a fundamental flaw in stereo due to a comb filter effect so a phantom center will introduce errors. That's why Toole states on page 399: "A direct–view video display is a challenge for the center loudspeaker. Some people give up in frustration and use the "phantom" center. DON'T DO IT!". So I guess Toole is pretty clear that a center speaker should be used.
Perhaps I am mistaken, but as I recall from Holman, there are two ears on the human head separated by about 6 inches or so for most people. If both speakers are playing a monophasic signal with frequency content in the midrange, a listener sitting in the median plane may experience cancellation at around 2 KHz or so, depending on atmospheric conditions and temperature. Holman describes many microphones used for stereo recording having a peak at around 2 Khz or so, which may need to be taken into account for surround mixing. It seemed to me that if one took the signal for a center channel and sent it to both stereo speakers, hence monophasic and dual mono, without equalization, there might be a problem with cancellation related to our binaural hearing apparatus. Since many audiophiles treat their rooms at the first reflection points, this would be more evident than if there were more room reflections. I may be flawed in my memory and reasoning here, and if so, I apologize.
Perhaps I am mistaken, but it seems to me that even the right screen will be extremely translucent, rather than truly transparent, especially when it comes to waves passing through at incidences further from normal, i.e. off-axis response. Am I mistaken?
Let me be clear that I'm not arguing in favor of phantom center channels. Markus wrote, "I would like to know why people consider having no Center as superior," and I am simply presenting some factors that may contribute to why some listeners may prefer the phantom center channel effect over an actual one in their setups. Now, granted, if they heard a carefully planned and optimally set-up surround sound system, they might change their minds, but practical realities may preclude an optimal setup for whatever reason. Interestingly, on his website, Linkwitz himself expresses a preference for a phantom center channel in most multichannel music situations, but I get the impression that he sits in the sweet spot.
Perhaps I am mistaken, but it seems to me that even the right screen will be extremely translucent, rather than truly transparent, especially when it comes to waves passing through at incidences further from normal, i.e. off-axis response. Am I mistaken?
Let me be clear that I'm not arguing in favor of phantom center channels. Markus wrote, "I would like to know why people consider having no Center as superior," and I am simply presenting some factors that may contribute to why some listeners may prefer the phantom center channel effect over an actual one in their setups. Now, granted, if they heard a carefully planned and optimally set-up surround sound system, they might change their minds, but practical realities may preclude an optimal setup for whatever reason. Interestingly, on his website, Linkwitz himself expresses a preference for a phantom center channel in most multichannel music situations, but I get the impression that he sits in the sweet spot.
So.... a cheap back-loaded Audio Nirvana FR could be used as the center speaker, just turn it down relative to the two stereo GOOD speakers to get just enough fill, but not overpower? If it is mainly for dialogue, then it could be limited to 500 Hz to 6 KHz, maybe a little lower, say 200 Hz to 6 KHz, would tame the beasty treble...
What material can be used for a screen that is acoustically transparent?
By the way, Dr. Gedde, after a bunch of reading and browsing and discussing at Audio-Circle, and discovering this oldie-goldie:
http://www.onhifi.com/product/amphion_xenon.htm
I've come to agree with the idea of a compression tweeter plus waveguide covering 1 KHz to .... 16 K, 20 K, whatever. Now, THAT was a paradigm shift!
I'll go back to your website and check on the waveguide prices, whether I could afford them.
Best, Charlie
What material can be used for a screen that is acoustically transparent?
By the way, Dr. Gedde, after a bunch of reading and browsing and discussing at Audio-Circle, and discovering this oldie-goldie:
http://www.onhifi.com/product/amphion_xenon.htm
I've come to agree with the idea of a compression tweeter plus waveguide covering 1 KHz to .... 16 K, 20 K, whatever. Now, THAT was a paradigm shift!
I'll go back to your website and check on the waveguide prices, whether I could afford them.
Best, Charlie
radianceaudio said:
No. The center is the most important speaker in a multichannel setup – it does not only have to reproduce dialogs - so it should be your best speaker. To avoid detrimental effects, the other front speakers should be the same make and model.
P.S. A lot of frequencies below 200 Hz can be found in a male human voice.
2 kHz dip - I follow the logic now. Don't agree with Floyd on absolutly no phantom center as I have tried it myself and find it quite acceptable.
Screens - don't get me started! But now that you did.
A commercial mega-buck acoustical screen was measured by me to be about 6 dB loss, almost across the board. That means that about 75% of the incident energy was reflected - just about the same as the open area, so that's not surprising. I experimented with some exotic screens - like a plain white low thread count bed sheet. The bed sheet had less than 1 dB loss and then mostly at the HF, nothing at all at the lows. And guess what, when stretched onto a frame so that it is flat (mist it after stretching and it will pull out all the wrinkles) it works at about 75% of the light reflectance of the mega-bucks screen. The decision was obvious and I haven't looked back. The bed sheet works great and even experts can't tell its not a Stewart (one guessed it was!) until I tell them. But everybody can tell that the sound is great. Thats a no brainer!
Screens - don't get me started! But now that you did.
A commercial mega-buck acoustical screen was measured by me to be about 6 dB loss, almost across the board. That means that about 75% of the incident energy was reflected - just about the same as the open area, so that's not surprising. I experimented with some exotic screens - like a plain white low thread count bed sheet. The bed sheet had less than 1 dB loss and then mostly at the HF, nothing at all at the lows. And guess what, when stretched onto a frame so that it is flat (mist it after stretching and it will pull out all the wrinkles) it works at about 75% of the light reflectance of the mega-bucks screen. The decision was obvious and I haven't looked back. The bed sheet works great and even experts can't tell its not a Stewart (one guessed it was!) until I tell them. But everybody can tell that the sound is great. Thats a no brainer!
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