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I recently had a malfunction with my SSP and the center channel is creating some additional noise, I used the phantom center channel function and surprisingly I am very pleased. I sit dead center so I assume sitting in the right or left chair might sound skewed. The overall front sound stage is more balanced, and I do not miss the center. My speakers are the Revel salon being powered by the Electrocompaniet Nemos which have been upgraded to 800 watts so I have lots of power to get these speakers humming. The center is their matching Voice speaker. powered by a 350 watt amp.


Question: Does one need a center channel if the L/R is large enough and seating angle are centered? I say no.
 

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It is considerably more natural than the "real" center channel ---- but, I allow my wife to sit in the center and without the center active, it just doesn't work for me.
 

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Yes, when you sit in the sweet spot, phantom mode is much much better.


With a center speaker, I always hear a sound coming from a tiny box rather than having a good and natural imaging.


If you're alone, a center speaker is just a gimmick.
 

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IT is good until you turn your head left or right or move off center. IT's great if you hve no center but otherwise, forget it.
 

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Quote:
Originally Posted by thebland /forum/post/17507006


IT is good until you turn your head left or right

Not on a good system.

Quote:
or move off center.

Why would I do that when I'm watching alone?
 
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I have done this in installs where there was no easy way to put in a center speaker. It does work (in some ways better as others have pointed out), but you do have to remain centered. If you have 8 chairs for instance, that poses a bigger problem.
 

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Quote:
Originally Posted by robena /forum/post/17507073


Not on a good system.




Why would I do that when I'm watching alone?

Yes... even in a good system (unless you can move your head and keep your ears equidistant to the L and R speakers). The soundstage collapses.
 

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Quote:
Originally Posted by joeycalda /forum/post/17506424


Does one need a center channel if the L/R is large enough and seating angle are centered?

Depends on if you like listening to the human voice reproduced as a dual-mono, phantom-imaged, comb-filtering source or if you like listening to it reproduced the way you hear it in real life. Most people are used to the former, so no surprise that it's their preference. Part of the reason is because most people use a "matching" centre: a speaker they will claim is a sonic match for their L/R speakers, but one they would never ever substiture for their L or R speaker.


Personally, after almost 2 decades of using a centre speaker, I wouldn't want to go back to a phantom image; certainly not for the most important content of a sound mix. YMMV.
 

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I wonder how much this depends on vertical (identical to mains) vs. horizontal (voice matched to mains) centers.


Since vertical centers, in many rooms, are impractical, using a horizontal center is typically the only option besides a phantom center. Unfortunately, from what I've read, doing so often creates more issues than it solves.


On the other hand, vertical centers seem to, more often, solve more issues than they create. However, while this arrangment may be more ideal for imaging quality, to achieve it means either raising the screen substantially or using an acoustically transparent screen. The former is not always practical. The latter is expensive and often compromises both video and audio quality.


Taking that into account, can/should we expand our comparsion to phantom center vs. horizontal and phantom center vs. vertical centers? Or, could it be said that in general, no matter the type of center, it is better to have one than go phantom if you want to increase the average imaging quality over all seats?
 

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There are also some perceptual cues that a phantom center will never deliver, like depth cues. Humans hear sounds coming from straight in front of them differently than two things 30 degrees off to the sides --- a real center is essential if you want to reproduce those cues properly.


However, given the poor way the center's been treated by both speaker companies and recording engineers, I'm not surprised at all that people prefer no center.


--Andre
 

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Phantom center will work a lot better with off center listeners with CD (constant directivity) speakers.


"Depends on if you like listening to the human voice reproduced as a dual-mono, phantom-imaged, comb-filtering source..."


What does comb filtering sound like? I don't remember noticing anything back when all we had is stereo.


I wonder if only some people notice it, like rainbows and DLP.
 

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There is no comb-filtering when you sit in the sweet spot because left and right signals are in phase.
 

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Quote:
Originally Posted by robena /forum/post/17509033


There is no comb-filtering when you sit in the sweet spot because left and right signals are in phase.

First, it is impossible for that to be true for both ears at the same time. Second, distributing the discrete center information to the L/R channels without compensating for the phase/time shifts produced will cause interference with the L/R information.
 

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Quote:
Originally Posted by sdurani /forum/post/17507591


Depends on if you like listening to the human voice reproduced as a dual-mono, phantom-imaged, comb-filtering source or if you like listening to it reproduced the way you hear it in real life. Most people are used to the former, so no surprise that it's their preference. Part of the reason is because most people use a "matching" centre: a speaker they will claim is a sonic match for their L/R speakers, but one they would never ever substiture for their L or R speaker.


Personally, after almost 2 decades of using a centre speaker, I wouldn't want to go back to a phantom image; certainly not for the most important content of a sound mix. YMMV.

Amen. There are valid justifications for using a phantom center but none of them derive from acoustic principles.

Quote:
Originally Posted by DreamWarrior /forum/post/17508543


Taking that into account, can/should we expand our comparsion to phantom center vs. horizontal and phantom center vs. vertical centers? Or, could it be said that in general, no matter the type of center, it is better to have one than go phantom if you want to increase the average imaging quality over all seats?

Generalizations are hard enough with only one variable (center: yes/no). Adding more variables moves the issues farther afield. That said, a proper discrete center is, imho, always superior to a phantom. How poor does the center speaker have to get to be inferior to a phantom? Dunno. Someone else will have to weigh on that.
 

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Quote:
Originally Posted by Kal Rubinson /forum/post/17509078


First, it is impossible for that to be true for both ears at the same time.

In absolute, you are right. But if we were that sensitive, no stereo system would work, they would all sound very bad considering the amount of information that is common to both channels.


That's not the case, stereo well done sounds wonderful, which shows that comb filtering is not an issue at all.

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Second, distributing the discrete center information to the L/R channels without compensating for the phase/time shifts produced will cause interference with the L/R information.

What phase shifts? We are adding 2 different and uncorelated signals, so there is no phase relationship between center and L/R to begin with. The addition is a linear process.


Could you elaborate?
 

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Quote:
Originally Posted by DreamWarrior /forum/post/17508543


Taking that into account, can/should we expand our comparsion to phantom center vs. horizontal and phantom center vs. vertical centers? Or, could it be said that in general, no matter the type of center, it is better to have one than go phantom if you want to increase the average imaging quality over all seats?

Then we would be expanding the discussion to several comparisons. You do bring up an interesting point though. Whenever I've seen comparsions between phantom centre vs hard centre it's typically turned out to be a comparison between phantom centre vs compromised hard centre.


During those discussions, digging a little deeper often reveals that the centre speaker is not the same model as the mains and/or not placed at the same height and/or orientation. It's rare to find someone who has lived with three identical speakers up front (all at the same height, all oriented vertically) preferring a phantom centre.


The above set-up isn't typical, so phantom vs compromised centre is probably a more practical discussion, since that's what most people have at home (hard to avoid when you have to accomodate a display). I know Kal uses three identical speakers up front, as do I, so some of us have compared phantom vs identical centre.
 

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Quote:
Originally Posted by robena /forum/post/17509157


In absolute, you are right. But if we were that sensitive, no stereo system would work, they would all sound very bad considering the amount of information that is common to both channels.

Well, that depends on the recording and mixing. With two mics to two speakers, the signals are not common, as they are when a single mic pickup is split to two speakers. That is apparent by comparing a true mono signal over the center speaker with a dual-mono signal (same, just split) over the L/R speakers. Timbre and quality are affected and shift with head position.

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That's not the case, stereo well done sounds wonderful, which shows that comb filtering is not an issue at all.

Indeed, with a true stereo feed or with one artfully created in the studio.

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What phase shifts? We are adding 2 different and uncorelated signals, so there is no phase relationship between center and L/R to begin with. The addition is a linear process.


Could you elaborate?

Consider a case where each of the L/C/R signals comes from its own mic feed in a live setup. Each mic 'hears' all the instruments but each hears each instrument with a unique level/phase relationship depending on its placement with respect to that instrument. So, an instrument in the center is 'heard' differently by the center and right mics. If your home processor splits the center feed to simply mix it with the right channel signal, the addition may be algebraically linear but the results will suffer because the centered instrument will be represented by two signals that differ in level and phase. (In the mastering studio, such a mix is done with sophisticated tools and ears in order to get the best outcome.) If the same happens on the left, it is hard to expect that the acoustic results will re-establish a pristine center signal.
 

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Quote:
Originally Posted by robena /forum/post/17509157


In absolute, you are right. But if we were that sensitive, no stereo system would work, they would all sound very bad considering the amount of information that is common to both channels.
Quote:
We are adding 2 different and uncorelated signals, so there is no phase relationship between center and L/R to begin with.

These two sentences contradict each other. Are stereo signals uncorrelated or do they shared common information?


Nevertheless, you mis-estimate the effect of comb filtering and our sensitivity to it. Comb filtering does not necessarily sound bad, but it is an audible effect that is markedly different than the original signal. Some people find it pleasing and familiar, while others don't like it.


Second, the cause of the comb filtering is the width of the human head separating the two ears. Given that this is one of the main physiological features that we use for spatial hearing and that the frequencies whose wavelengths are closest to that separation width are in our most sensitive hearing range (hmm, I wonder why?), it should not be at all surprising that we are indeed that sensitive to it.


Comb filtering is also not the only bad side-effect from phantom centers. But I don't think a meaningful discussion of the efficacy of real centers can be had without an examination of the recording process, which has really let center channels down. The only good recordings I've heard that really show why a real center is needed were made in the 60s --- the Mercury and RCA LS 3-channel recordings.


--Andre
 

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Quote:
Originally Posted by noah katz /forum/post/17508861


What does comb filtering sound like?

It sounds slightly hollower/phasier when compared to the same sound without the combing. Easier to demonstrate than describe, even if you don't have three identical speakers. Close your eyes and play a mono source (AM radio announcer works well) through your front L/R speakers, and listen to the phantom image directly in front of you. Then unplug one of the speakers and directly face the other other one, listening to the same mono source.
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I don't remember noticing anything back when all we had is stereo.

What were you comparing it to? Did you used to notice 3:2 judder when all we had was NTSC television?
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I wonder if only some people notice it, like rainbows and DLP.

Sure. And sometimes, it's it's not inherent sensitivity, just something you've become used to. Living with NTSC all my life, I never noticed 3:2 judder. When friends showed up from England, they'd spot it right away. It's not like they have uncanny visual acuity, they just haven't spent a lifetime getting used to it. (Took an A/B comparison for me to first see it.) Likewise, I've been using a centre speaker (for all sources) since 1991, so a phantom centre doesn't sound the same to me. No golden ears here, just what I've become accustomed to for the last two decades.
 

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I've mentioned this before but...


In our family room I have a 42" plasma with small Spendor 3/5 monitors on either side, spread about 5 feet apart. It produces the best illusion of the sound coming right from the screen that I've ever experienced, outside of projector set ups using AT screens. In fact, I've heard some AT set ups that don't do as well as my set up, in that I can "hear" and locate the center speaker behind the screen, whereas there is no such artificial effect with my phantom center.


Probably more surprising to me is how well the illusion remains even from off-axis. It has truly spoiled me in this regard.


I'm stuck using a center channel in my projection set up - a very nice L/C/R from Hales - and tonally the set up sounds gorgeous. But in terms of the illusion of the sound coming from the screen, it doesn't compare to the phantom imaging of my plasma set up.
 
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