Hi Everyone,
I admit the post is a little inflammatory, but I would really like your input on this subject. First, a little background about me. In the early 80's I worked for one of Dolby's competitors in the motion picture sound industry, Smart. We prided ourselves on having the best sounding equipment, audiophiles ruled there.
Anyway, it was my understanding, if not the common understanding, that the purpose of having 3 (sometimes 5 for magnetic sound) speakers behind the screen, as well as the very strong steering of Dolby Surround was to give everyone in the theater a good experience. This meant that if an audience member was in the very front left seat, we wanted them to be able to hear dialogue coming from the center and any effects from the right.
So, here I am, rather prejudiced now. For flat screen TV's in an average apartment to me the center channel seems completely unnecessary. I get good imaging from left to right. Not wanting to spend another $1,000 or more to add a center, I don't think I'm missing anything and shake my head to see so many audio and movie philes focus on having the 5 channel sound.
So, my earnest question to you all, is do you have direct experience with and without a center channel that says I'm missing out?
Thanks!
Eirk
I admit the post is a little inflammatory, but I would really like your input on this subject. First, a little background about me. In the early 80's I worked for one of Dolby's competitors in the motion picture sound industry, Smart. We prided ourselves on having the best sounding equipment, audiophiles ruled there.
Anyway, it was my understanding, if not the common understanding, that the purpose of having 3 (sometimes 5 for magnetic sound) speakers behind the screen, as well as the very strong steering of Dolby Surround was to give everyone in the theater a good experience. This meant that if an audience member was in the very front left seat, we wanted them to be able to hear dialogue coming from the center and any effects from the right.
So, here I am, rather prejudiced now. For flat screen TV's in an average apartment to me the center channel seems completely unnecessary. I get good imaging from left to right. Not wanting to spend another $1,000 or more to add a center, I don't think I'm missing anything and shake my head to see so many audio and movie philes focus on having the 5 channel sound.
So, my earnest question to you all, is do you have direct experience with and without a center channel that says I'm missing out?
Thanks!
Eirk
It depends on the setup.
If there's only one viewing seat and the front left & right speakers are good enough for voices to sound like they're coming from the screen, then go ahead, use a phantom centre.
If lots of people want to sit around a room, it'd be better to have a centre speaker. Note the horizontally laid-out ones that are common these days are a bad idea - all the lobing will be in the horizontal axis. Not good.
If there's any asymmetry in the L/R speaker positioning, I'd also use a centre speaker.
Chris
If there's only one viewing seat and the front left & right speakers are good enough for voices to sound like they're coming from the screen, then go ahead, use a phantom centre.
If lots of people want to sit around a room, it'd be better to have a centre speaker. Note the horizontally laid-out ones that are common these days are a bad idea - all the lobing will be in the horizontal axis. Not good.
If there's any asymmetry in the L/R speaker positioning, I'd also use a centre speaker.
Chris
I feel like it is always a compromised setup because you are dealing with a screen in the exact spot that you need a full range speaker that is phase coherent with the Left and Right speakers which are usually vertically aligned drivers. Tweeters and mid driver should at the very least be vertically aligned on the center with the same crossover as the left and right speakers. Listeners can not detect large phase distortions in a system as long as all the speakers have the exact same phase distortion. If you put one of the speakers out of phase with the others it can easily be picked up on.
So basically you need an acoustic transparent screen with a speaker behind it to have a no compromise system. Just seems like too much work.
I think there are some defects though in a phantom center beyond the normal swaying of the stereo image as you move to the right or left. There is a sort of collapse in the sound that is not evident until you clear up the problem a little bit and then you can sort of notice it with an A/B test. But it is my opinion that this collapse of the sound is not because it's a phantom image and not coming from it's own discrete driver, but it's due to a lack of side wall reflections increasing intelligibility of the phantom center. Using some simple wave field synthesis principles and making a simple synthetic reverb that creates a first reflection on the recording actually can cure this problem a little bit provided that the side wall reflections on the recording come at your ears from the left and right side speakers.
Me I am a quad guy. I think after a quad equal distance set up of 4 speakers any additional speakers that you add are getting you into diminishing returns on your investment. To put it simply - Stereo is a huge improvement on mono, Quad is a huge improvement on stereo, but past that you are only getting slight improvements for your money.
So basically you need an acoustic transparent screen with a speaker behind it to have a no compromise system. Just seems like too much work.
I think there are some defects though in a phantom center beyond the normal swaying of the stereo image as you move to the right or left. There is a sort of collapse in the sound that is not evident until you clear up the problem a little bit and then you can sort of notice it with an A/B test. But it is my opinion that this collapse of the sound is not because it's a phantom image and not coming from it's own discrete driver, but it's due to a lack of side wall reflections increasing intelligibility of the phantom center. Using some simple wave field synthesis principles and making a simple synthetic reverb that creates a first reflection on the recording actually can cure this problem a little bit provided that the side wall reflections on the recording come at your ears from the left and right side speakers.
Me I am a quad guy. I think after a quad equal distance set up of 4 speakers any additional speakers that you add are getting you into diminishing returns on your investment. To put it simply - Stereo is a huge improvement on mono, Quad is a huge improvement on stereo, but past that you are only getting slight improvements for your money.
Last edited:
A third channel should really be in the back (of the room) this giving you the depth of field. Since all rooms are rectangular and not spherical, two stereo pairs F/B seem fine. in the same way 6 point sources for Up/Down would be plausible, or in a standard room 8 speakers for each corner or sound source.
Depends also on where you live. I have my centre speaker turned up a little so I can hear the dialogue without the L/R effects waking up the neighbourhood 🙂
That may be the first time I have heard a very good reason for a center channel. 🙂
Best,
Erik
Awww C'mon 🙂 It's TV Tunes (or More likely replays of 'transformers' movies)
High Fidelity is a misnomer.. Sound Effects are what it's all about.
Just like in Movie theatres with their universaly Horrid Sound systems.
High Fidelity is a misnomer.. Sound Effects are what it's all about.
Just like in Movie theatres with their universaly Horrid Sound systems.
I take exception to that, the movie auditoriums, especially the one's we worked with AMC to set up were really good sounding. Haven't heard a nice one in decades though.
In my experience, phantom center of stereo reproduction (2 channel) is not very convincing. Usually it is not possible to be fully convinced that sound is coming from a definite location laterally in or near the middle between the pair of left and right channel speakers. This experience of mine is while sitting at the "sweet spot".
As I say, this just my personal subjective response. Not having tried setting up a center channel, I'm just speculating, but my guess would be that the addition of a center channel would result in improved localization stability.
As I say, this just my personal subjective response. Not having tried setting up a center channel, I'm just speculating, but my guess would be that the addition of a center channel would result in improved localization stability.
Well for me that's been a matter of speaker set up. Once I get that right there is no problem with the center at all. 🙂
For HT I have a center speaker (no subs) but for music almost always disconnect it and listen to "audiophile tracks" in stereo.
Personally, I would never, ever go back to watching movies (or tv) without a center channel. It makes dialog infinitely clearer, localized, and intelligable. The center channel should be the best speaker in the front lineup. 🙂
+1 ^
I used to really like DVD's that had audio option of "Dolby 2.0". It seemed the voice/dialogue would always be clear. More often though I find audio options to be either none at all, or Dolby 5.1 or DTS. My A/V Receiver at the time didn't seem to do a good job of down-mixing a 5 channel track to stereo. For a while I ran a center just so I could hear the voices.
To me the more pressing issue is when someone is listening to 2ch music and pushes the button to up convert it to 5 channels. I thought such a practice should be outlawed, because it made my music sound full of echoes and destroyed the stereo image.
There is history, practice and science behind that center channel. It's a real benefit for large spaces. I've even used a vocal-only center cluster for live music PA. Also used to do Dolby and THX alignments in cinemas, so have some familiarity with the subject.
For a small space and narrow angle, the center isn't going to be as important, but it can still help dialog. I really doubt that I would spend $1000 on a center channel, tho. Isn't this a DIY forum?
For a small space and narrow angle, the center isn't going to be as important, but it can still help dialog. I really doubt that I would spend $1000 on a center channel, tho. Isn't this a DIY forum?
I've got a 3.1 setup, left, right, mid and sub, and I noticed a dramatic improvement in positioning when we got the centre (I see both spellings are used in this thread already) channel speaker.
A good example is the film WALL-E, where in some of the early scenes the little robot moves across a series of stationary landscapes while the camera stays still. With the three channel setup, you can hear the robot coming when it appears to be three feet off to the left of the screen, and follow it with your eyes closed as it crosses the screen to the right and disappears off. The positioning is very clear.
A totally separate issue is that in many films or series, the incidental music is fed to the left and right channels, while the dialog all comes through the centre. 'Grey's Anatomy' does this a lot. The background music gets so loud sometimes it is a real benefit to be able to localise the dialogue to a different channel, and makes it easier to follow. I'm not talking about distortion being a factor here, it is just that the ears can focus on the dialogue because it is coming from one direction, while the ambient effects spread out much more.
An externally hosted image should be here but it was not working when we last tested it.
A good example is the film WALL-E, where in some of the early scenes the little robot moves across a series of stationary landscapes while the camera stays still. With the three channel setup, you can hear the robot coming when it appears to be three feet off to the left of the screen, and follow it with your eyes closed as it crosses the screen to the right and disappears off. The positioning is very clear.
A totally separate issue is that in many films or series, the incidental music is fed to the left and right channels, while the dialog all comes through the centre. 'Grey's Anatomy' does this a lot. The background music gets so loud sometimes it is a real benefit to be able to localise the dialogue to a different channel, and makes it easier to follow. I'm not talking about distortion being a factor here, it is just that the ears can focus on the dialogue because it is coming from one direction, while the ambient effects spread out much more.
Where the amplitude and phase of a center sound source is the same in both the left and right channel speakers, and the listener faces directly forward positioned at the lateral middle of the speakers, then yes, the listener hears the center sound source as directly in front of him.
However, if the listener shifts his head to one side, then the resultant change of relative intensity at his ears is different than that which would occur if the center sound were actually emanating from a source directly in front of him. That is, the phantom center sound produced by stereo reproduction is emanating from two different locations, the locations of the left and right channel speakers.
In attempting to locate the direction of a source of sound, rabbits twist their ears around and humans shift their heads. The twisting/ shifting is a necessary part of localizing a sound source.
Is it possible to obtain a center channel signal from stereo program material, or must one use program material that has been engineered to contain left, right and center signals?
Regards,
Pete
However, if the listener shifts his head to one side, then the resultant change of relative intensity at his ears is different than that which would occur if the center sound were actually emanating from a source directly in front of him. That is, the phantom center sound produced by stereo reproduction is emanating from two different locations, the locations of the left and right channel speakers.
In attempting to locate the direction of a source of sound, rabbits twist their ears around and humans shift their heads. The twisting/ shifting is a necessary part of localizing a sound source.
Is it possible to obtain a center channel signal from stereo program material, or must one use program material that has been engineered to contain left, right and center signals?
Regards,
Pete
As stated above, when you are exactly between the speakers, the phantom center image is petty good. But as you move left or right from that position, the phase differential at certain frequencies causes frequency selective amplitude variations that confuse the brains ability to hear a clear center image.
Some decoders with steering might work pretty good. I've got an old Carver preamp from the ProLogic 1 era with steering that doesn't impress me. I may just use a L+R for the center, and run the signals for the left and right speaker through an L-XR matrix (that is only active above 100HZ or mono bass gets attenuated a bunch) to largely cancel the L+R out of their feeds. No active steering. Active steering is very difficult to do well. I've studied it a bunch.
If your sound system has evolved into a small video theater like mine did (42 inch HD TV in the middle), I think it's worth having a center speaker.
Some decoders with steering might work pretty good. I've got an old Carver preamp from the ProLogic 1 era with steering that doesn't impress me. I may just use a L+R for the center, and run the signals for the left and right speaker through an L-XR matrix (that is only active above 100HZ or mono bass gets attenuated a bunch) to largely cancel the L+R out of their feeds. No active steering. Active steering is very difficult to do well. I've studied it a bunch.
If your sound system has evolved into a small video theater like mine did (42 inch HD TV in the middle), I think it's worth having a center speaker.
I have done tons of A/B comparisons with and without the center channel and the difference is VERY noticeable. Dolby Digital 5.1 tracks are recorded with center channel separation, that means you would need to switch your source to DD 2 channel to get the proper recording to listen to without a center. This is the BEST listening choice IMO, without a center. I also do not like to listen to music with the center since the music is recorded in stereo.
Concert DVD/Bluray is where you really find out how good your center channel is! Because you can switch between 5.1 and 2 channel.
For me personally I like my center channel for movies...and it sounds really good for concerts too, but that might be because I built it. 😉
Concert DVD/Bluray is where you really find out how good your center channel is! Because you can switch between 5.1 and 2 channel.
For me personally I like my center channel for movies...and it sounds really good for concerts too, but that might be because I built it. 😉
My attempt was to describe a listener staying exactly in the middle between the speakers, and shifting his head, not moving to the left and right. My point was that you can be in the best possible position to localize the phantom center sound source as directly in front of you, but the phantom sound source is not well established where it should be (precisely in front of the you) because normally you are doing head shifting revealing the artificiality.
From what you say further, it would seem that it is problematic to get a "legitimate" center signal from stereo material. L + R isn't really it.
Regards,
Pete
Last edited:
- Status
- Not open for further replies.