When you add L and R in phase, you cancel R-L and L-R program content. That gives you the signal for the center speaker.
When you do an L-XR, meaning subtracting part of -R from L (usually about half) (and R-XL), you will perceive that a large part of L+R has been removed. Now you have signals for the left and right speakers that has less L+R per unit of L-r or R-L.
It's certainly not perfect, but reasonably effective, and doesn't involve the attack and decay times that come with "intelligent" active steering. If you know of a better way to derive 3 channels out of two, please do tell.
When you do an L-XR, meaning subtracting part of -R from L (usually about half) (and R-XL), you will perceive that a large part of L+R has been removed. Now you have signals for the left and right speakers that has less L+R per unit of L-r or R-L.
It's certainly not perfect, but reasonably effective, and doesn't involve the attack and decay times that come with "intelligent" active steering. If you know of a better way to derive 3 channels out of two, please do tell.
I've wondered about the phasing issue. Does anyone have actual experience mixing up 2-ways and 3-ways?
I have a pair of PSB Stratus Goldi 3-ways that I use for music but I've wondered about trying 3-channel or 5-channel matrixing, but the only matched center speakers are 2-way. So everything above 250 hz, or under it, might end up being out of phase with the center.
I have a pair of PSB Stratus Goldi 3-ways that I use for music but I've wondered about trying 3-channel or 5-channel matrixing, but the only matched center speakers are 2-way. So everything above 250 hz, or under it, might end up being out of phase with the center.
I've wondered about the phasing issue when mixing different L/Rs and center speakers. Does anyone have actual experience matching 2-ways with 3-ways in front? How big of a problem is it?
I have a pair of PSB Stratus Goldi 3-ways that I use for music. I was thinking of trying them with 3-channel or 5-channel upmixing (I would use Dolby PLII, etc, not homebrew) but the only matching PSB Stratus center speakers are 2-ways. Which could mean that everything below 250Hz, or everything above it, could be out of phase between the Golds and the center.
I have a pair of PSB Stratus Goldi 3-ways that I use for music. I was thinking of trying them with 3-channel or 5-channel upmixing (I would use Dolby PLII, etc, not homebrew) but the only matching PSB Stratus center speakers are 2-ways. Which could mean that everything below 250Hz, or everything above it, could be out of phase between the Golds and the center.
From an old paperback book that I have (Inside Electronics By Monroe Upton, 1964), Upton says that originally the M-S recording technique was complemented with reproduction of the "M" channel by a speaker system positioned directly in front of the listener, and the "S" channel carrying L-R by a speaker system turned sideways.
The M mike has a cardiod pick-up pattern and facing directly towards the sound stage while the S mike is at a 90 deg. angle to the sound stage with a horizontal figure 8 pick-up pattern. This would work out quite well, I think, as the center is reproduced by a speaker directly in front of you almost exclusively given the figure 8 pick-up pattern of the S mike.
Now the next thing is to find CDs where recording was done with a M-S mike and the two tracks on the CD are the M and S signals (LOL).
-Pete
The M mike has a cardiod pick-up pattern and facing directly towards the sound stage while the S mike is at a 90 deg. angle to the sound stage with a horizontal figure 8 pick-up pattern. This would work out quite well, I think, as the center is reproduced by a speaker directly in front of you almost exclusively given the figure 8 pick-up pattern of the S mike.
Now the next thing is to find CDs where recording was done with a M-S mike and the two tracks on the CD are the M and S signals (LOL).
-Pete
Dolby Pro Logic 2 does have a music mode, but apparently you only get it on A/V Receivers that I can't afford. The real version has 3 modes, if I remember correctly. My $500 Yamaha receiver appears to have only the movie mode, so heavy active steering. With music I find that simpler is usually better, meaning no active steering, but do try it. Especially if your version has the music mode option. I haven't tried my PLII in so long I don't remember if it worked well with music.
I mixed my album in Stereo and Surround at the same time. I basically skip the encoder and just monitor the decoder on the fly.
In the manuals for my speakers it recommends that to mix best you need every speaker to be exactly the same. Center needs to be the same as the side speakers because of phasing issues. I have seen a few lines of speakers that offer a horizontal speaker that has the same vertical alignment as the side speakers though for the mid and tweeter. But i think the best for surround sound music if you are using a center and mixing is to have them matched.
I don't like the idea of a center with music because i make instrumental music and i find it really boring to use one of those things and overly complicated to pan through one.
I think that a lot of the logic based decoders are actually un-needed and were maybe born out of the failed formats SQ and QS and the quest to make those systems actually work. I think most all of the decoders have too many variables and too much potential to degrade the audio with weird phase shifts that i don't see a need for.
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If the center speaker is said to be matched to the L and R speakers of the same brand, you'd think a phase issue would be minimal. Dolby PLII has active steering, so phase addition of the center speaker with the L and R speakers should be minimal. That might be the best argument in favor of active steering.
But there's also this:
Adding a center channel would add another sound source that would likely be shifted in time, and therefore phase, relative to the left and right speakers. This phase shift could be part from the crossover differentials, and part because of any difference in distance to the listener, relative to either of the other speakers. Without active steering the center images would experience some comb filter effect when more than one signal adds at the listeners ear.
With no center speaker there are only two sound sources L&R that will have some comb filter effect phase issue on images in the middle, due to any distance differentials.
Room reflections will usually present another substantial complex comb filter effect.
The good news is that all of these comb filter mechanisms have their cancellations at different frequencies, so they tend to fill each other in, by the time the sound reaches the listener.
In the case of a center speaker crossover swapping the phase above or below a crossover frequency (250HZ), it depends what phase it's being compared to in the L or R speakers, and could cause a deficiency if the phase differential is more than 90 degrees. I guess that's the best argument for having the center speaker phase response not too different from the L and R speakers. With the above mentioned variables also at play, I haven't personally found it to be a noticeable issue. Perhaps because I do presently have active steering enabled.
My system has L and R speakers with X = 100 and 1.4kHZ, 4 pole, and my center speaker which is just two way has X = roughly 700HZ, 1 pole passive. My center speaker also has secondary woofers that are only active below 100HZ with a passive one pole low pass. So I've got a whole mish-mash of phase issues that don't seem to matter. Maybe it could be even better with exactly matched crossovers, drivers and distance to the listener. Especially if I had only passive steering which creates substantially less separation of signals.
Sorry if this sounds like I just woke up. I did.
There are some other problems with a phantom center. See my thread here:
http://www.diyaudio.com/forums/multi-way/277519-fixing-stereo-phantom-center.html
http://www.diyaudio.com/forums/multi-way/277519-fixing-stereo-phantom-center.html
After re-reading the article, Fixing the Phantom Center, I realize that my last entry was a guess at what was meant. It seems that the bottom line is that you add decorrelated reverbs to each channel that are so short term that they are not perceived as reverbs, but cause comb filter cancellations of the phantom center to be largely filled in by the various non-correlated delays. Much like how room reflections do that. The paper recommends BW limiting the processing to above 1kHZ so timing cues in the lower midrange aren't scrambled, which they are anyway due to inter-aural crosstalk. But for headphone compatibility that makes good sense.
But if the delay times are that short as to not be perceived (2mS was mentioned), won't that cause the distance between the nulls to be perceptable by a person sitting near the L or R speaker? A sort of frozen phlanging effect? The article mentions that the improvements are only significantly perceptable in relatively dry environments. Maybe if this same technique was used with an actual center speaker, it might be a significant improvement. 3 different effectively decorrelated reverb delay clusters adding like resonances inside a rectangular speaker cabinet, designed such that double ups are minimal. It reminds me of open baffle speakers in that it's technically a step away from absolute fidelity, but can give us something more enjoyable.
But if the delay times are that short as to not be perceived (2mS was mentioned), won't that cause the distance between the nulls to be perceptable by a person sitting near the L or R speaker? A sort of frozen phlanging effect? The article mentions that the improvements are only significantly perceptable in relatively dry environments. Maybe if this same technique was used with an actual center speaker, it might be a significant improvement. 3 different effectively decorrelated reverb delay clusters adding like resonances inside a rectangular speaker cabinet, designed such that double ups are minimal. It reminds me of open baffle speakers in that it's technically a step away from absolute fidelity, but can give us something more enjoyable.
I did mine a little different than most. I have 5.1 system with a vertical center channel above the TV and the L&R and spread far apart beside the TV. The two rear channels are split into four speakers with two either side of the couch pointing toward the viewer and the other 2 behind the couch pointing toward the viewer. Works quite effectively. If I turn off the centre channel, all is lost.
I have the opposite of a phantom center as it is stronger than the L or R channels. It is the most prominent speaker of the lot.
Michael, this is at the other place.
I have the opposite of a phantom center as it is stronger than the L or R channels. It is the most prominent speaker of the lot.
Michael, this is at the other place.
That's interesting Cal, and unusual. How the tonal balance of the center?
Bob, I replied to your post, but it went missing. 🙁
Bob, I replied to your post, but it went missing. 🙁
The center channel is vocal oriented so it looks like someone did the upside down smile on an equalizer.
DIY to me does not necessarily imply a price point, but I was including the cost of the electronics in that. 🙂
I gave up on my center channel when that channel stopped working from my receiver. After that one of the other front channels also gave out, and I now my L/R come from my tube amp. My room is small, I can't remember the last time it was more than my wife and I on the couch, and mostly it is just me watching GoT when I turn on the surround. The center speaker has been sitting in a corner for 3-4 years now unused. I also can't remember the last time I turned on the subwoofer. It just seems unnecessary. I do like the effects from the rear, so I leave those in the mix.
There was a time, back when HT was beginning to get popular, that I went through the trouble of a universal remote, balanced sound, video and audio calibration, even 3D. Now, I mostly just use the tv speakers, and I haven't watched anything in 3D after maybe 6 months of having it. It was like watching mini people in a fish tank.
There was a time, back when HT was beginning to get popular, that I went through the trouble of a universal remote, balanced sound, video and audio calibration, even 3D. Now, I mostly just use the tv speakers, and I haven't watched anything in 3D after maybe 6 months of having it. It was like watching mini people in a fish tank.
No, I don't given that stereo recording encompasses a multiplicity of different recording techniques.
There should be research done to identify the best method for producing stereo recordings and then standardize it. If the imaging of stereo recording is to be improved, I think that that would require a matched system of recording and reproducing.
I know, LOL (lots o' luck). Sorry about the late direct reply.
Regards,
Pete
The local AMC to my considerable surprise now once again after renovation has excellent sound, good digital projection (4K capability) and very comfortable pleather recliners.
With horn 3 way onken style speakers, or split biamped Markaudio 12P/12PW dipoles, 2.1 is fine for me, and the power of suggestion (the images onscreen), I often seem to hear things above, beside, and around me.
I much prefer this to the 4 KEF bookshelf speakers plus 3 channel Tannoy dc "soundbar" in my "proper" 7.1 channel setup.
I've tried out the Markaudio panels as rear channels, but find more than a 2.1 speaker rig pulls me out of the film.
And I used to think more channels were better.
I much prefer this to the 4 KEF bookshelf speakers plus 3 channel Tannoy dc "soundbar" in my "proper" 7.1 channel setup.
I've tried out the Markaudio panels as rear channels, but find more than a 2.1 speaker rig pulls me out of the film.
And I used to think more channels were better.
Well what a difference a year makes. 🙂 Since my original posting I have experimented with adding a center channel amp and designed my own MTM speaker for it, the LM-1C. I actually really like a dedicated center, but I wouldn't call it mandatory.
In combination with the rest of a well tuned 5.1 system it's really nice.
The biggest difference I have found is the center channel removes a muffled experience to the phantom center, and makes the center sounds much more seamless.
Would I say it's a must? No. Worth the extra speaker and amp? I actually think so, as part of the entire experience.
Best,
Erik
In combination with the rest of a well tuned 5.1 system it's really nice.
The biggest difference I have found is the center channel removes a muffled experience to the phantom center, and makes the center sounds much more seamless.
Would I say it's a must? No. Worth the extra speaker and amp? I actually think so, as part of the entire experience.
Best,
Erik
For the application you are describing, my opinion is that it's not only unnecessary, but an annoyance both visually and aurally.
Hi Kirchhoff
I was with you before, but having actually tried it, I no longer feel the center channel is unnecessary, but rather a good improvement. It's a difficult thing budget wise, especially if you are buying speakers off-the-shelf though. I think it's up to the individual about how they enjoy their system, and who with. I also think this makes a bigger deal for those audiophiles who actually have friends and family over to watch a movie with who may sit to the sides of the throne, or captains chair. The center channel does in fact help keep sound rooted in the center.
But... I also think it has been over-hyped and I don't feel it requires a crusade one way or the other. I would say if you can afford it, and spend a lot of time wiht movies, DO IT. Properly positioned and integrated I absolutely did NOT find it an aural distraction.
One thing I should also point out is that while the center channel tends to have dialogue, it's never been a different channel acoustically or electrically ( outside of the processing ) in theaters. Movies will often have foley or whatnot in it, and dialogue may in fact move to the sides. It's entirely up to the sound editors. There's no hard and fast rule. Only in the home with the restrictions of the speaker needing to go above or below a non-porous flat-panel has the center channel speaker taken on a different configuration. In all theaters I knew of, and thanks to work that was around 3-4 dozen auditoriums, the L, C and R amps and speakers were identical, but they had the benefit of sitting directly behind the screen as opposed to completely outside the frame of the screen.
There's an entire separate thread in this forum about "fixing the center channel" and it was too much for me, but I reiterate, the sound is noticeably better from a real center vs. phantom. It's less muffled and the midrange is livelier and more present and this was with a carefully matched and EQ'd center.
What I did also discover is that the idea that speakers should match very closely mechanically was not true. Meaning, identical tweeters, same line mid woofers, etc. was not very important. I had very good results with my AMT/Scanspeak mains with $30 center channel for a week. Long enough to convince me it was worth building a better center channel. 🙂 When I do full 5.1 I still use the AMT/Scanspeak L and R but my center is a Vifa/Peerless with a ring radiator tweeter. Of course, I used the main curves as guides for the crossover design AND I use miniDSP to help fix placement issues. It's completely seamless, even though my side speakers are Mundorf/Scanspeak and center is Vifa/Peerless.
Again, I'm not championing a center channel as THE ONE TRUE WAY to do Home Theater, or disparaging those who don't. I'm just saying, I was converted by experimentation and experience. If you love movies, life is too short to live without a well integrated sub and a good center channel. 🙂
Given budgetary or spacial restrictions though, if I had to choose between my sub and center channel speaker, I'd give up the center first. 🙂 Still, having it all is most excellent.
Best,
Erik
I was with you before, but having actually tried it, I no longer feel the center channel is unnecessary, but rather a good improvement. It's a difficult thing budget wise, especially if you are buying speakers off-the-shelf though. I think it's up to the individual about how they enjoy their system, and who with. I also think this makes a bigger deal for those audiophiles who actually have friends and family over to watch a movie with who may sit to the sides of the throne, or captains chair. The center channel does in fact help keep sound rooted in the center.
But... I also think it has been over-hyped and I don't feel it requires a crusade one way or the other. I would say if you can afford it, and spend a lot of time wiht movies, DO IT. Properly positioned and integrated I absolutely did NOT find it an aural distraction.
One thing I should also point out is that while the center channel tends to have dialogue, it's never been a different channel acoustically or electrically ( outside of the processing ) in theaters. Movies will often have foley or whatnot in it, and dialogue may in fact move to the sides. It's entirely up to the sound editors. There's no hard and fast rule. Only in the home with the restrictions of the speaker needing to go above or below a non-porous flat-panel has the center channel speaker taken on a different configuration. In all theaters I knew of, and thanks to work that was around 3-4 dozen auditoriums, the L, C and R amps and speakers were identical, but they had the benefit of sitting directly behind the screen as opposed to completely outside the frame of the screen.
There's an entire separate thread in this forum about "fixing the center channel" and it was too much for me, but I reiterate, the sound is noticeably better from a real center vs. phantom. It's less muffled and the midrange is livelier and more present and this was with a carefully matched and EQ'd center.
What I did also discover is that the idea that speakers should match very closely mechanically was not true. Meaning, identical tweeters, same line mid woofers, etc. was not very important. I had very good results with my AMT/Scanspeak mains with $30 center channel for a week. Long enough to convince me it was worth building a better center channel. 🙂 When I do full 5.1 I still use the AMT/Scanspeak L and R but my center is a Vifa/Peerless with a ring radiator tweeter. Of course, I used the main curves as guides for the crossover design AND I use miniDSP to help fix placement issues. It's completely seamless, even though my side speakers are Mundorf/Scanspeak and center is Vifa/Peerless.
Again, I'm not championing a center channel as THE ONE TRUE WAY to do Home Theater, or disparaging those who don't. I'm just saying, I was converted by experimentation and experience. If you love movies, life is too short to live without a well integrated sub and a good center channel. 🙂
Given budgetary or spacial restrictions though, if I had to choose between my sub and center channel speaker, I'd give up the center first. 🙂 Still, having it all is most excellent.
Best,
Erik
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