Phantom Center Channel...Anyone?

Paid a visit to Bryan’s (aka Roni) place yesterday and have a blast of time listening to his new AVM 90 setup. His setup and mine are very different and so are the sound and bass signature. I can see he has had spent several hours tweaking his system to his own liking (preference). I’m surprised to hear that despite using the same Anthem product, the sound can be so different. I ascribed the difference to the type of speakers and subwoofers used by each individual. Instead of describing what I “heard” and “feel”, I encourage anyone who is interested in Anthem to pay bro Bryan a visit. Enuff said.

Phantom Center Channel

One interesting discovery by Bryan that he shared so “passionately” with me is the use of “phantom center” channel, meaning the “deactivation” of the center channel when watching movies. I have to admit that this is my first time listening to a “phantom center” channel and it does sound “different” and “refreshing” in some ways but it may not be applicable for use in every scenario. The most distinct or stood out to me using this phantom center channel setup is the clearer separation of sound depth and its dimensionality. What this means is that the center channel which can sometimes be over-powering, be it due to the user increasing the trim levels to make the dialogue more intelligible could in a way drown out the sound panning from left to right. If one is to remove the center channel from the equation, one will immediately experience a slight drop in the “fullness” of the dialogue spoken but what you gain in return is a more “balanced” and “cohesive” sound throughout the entire front stage. Yes, it affects only the front stage.


While it may sound cool, there are a few pre-requisites that I will need to mention. Firstly, one needs to be seated at the MLP (prime seat) to make this work. If you sit either on the left or right seat, meaning not in the middle, then this whole “phantom center” channel setup will not work as intended since one is no longer equidistant between the left and right speakers. Secondly, you need a bigger front stage for this setup to work. For instance, it doesn’t work for me since my front stage is rather limited in space which restricts the sound panning to achieve a “wider” sound stage.

I would like to hear your comments on any anecdotes of using this approach, can we really do away with the center channel if you ONLY have one MLP or do you think center channel is still a must-have since 65% of the movie soundtrack derives from the center channel to deliver clear and crisp dialogue.

@Ronildoq, perhaps you may wish to share your experience with everyone on your center channel being behind an AT screen and how it affects the overall sound vis-a-viz to your mains. For me, I’ll still stick with center channel, what about you? Do share with us your experience.

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Yes yes! I am so excited with the Phantom Centre. After the demo session with Bro Desray, it the midst of it after the “you cant handle the truth demo” i revealed the secret, there is no Centre Speaker playing in the chain!! lol

Dont get me wrong, i have a centre speaker behind the AT screen, this is what it looks like behind the AT screen.

After dialing in the system, i was testing out a lot of the demo materials that i am familiar with. So i played them to see how it sounded like with the various profile.

Profile A was with EQ up to 200hz
Profile B was with EQ up to 1khz
Profile C was with EQ up to 20khz
Profile D was Stereo

So after testing A,B,C, i thought why not lets try D see how it sounds like, so played the system without the centre speaker. and i was like shocked! hang on a second, why is it so much nicer and clearer ?

Thats how it all started… This was just 3 days ago only…

Ill share below now, what i have discovered… and which is nicer for me…

The placement of the center is too high just as I suspected. Maybe bring it down a little to be in line with the ear level since your couch is quite low. Maybe, just maybe it can have a more coherent panning?

ya its slightly higher than the mains, its actually dead centre of the screen. just realised also , but its clarity is just different when you have a piece of cloth (PJ screen) blocking its path… somehow the clarity is not the same as L+R

Ok let me share further … still figuring it out… a few observations made and ill share that as well… i have the HT profile turned on with centre also… so its really easy to AB

Try, if you can…to lower the center speaker or angle it lower (say 15 degree tilt) and you may be pleasantly surprised how it pan out.

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ok so let me share the journey. Once upon a time…

This above was my set up many years ago, i had the centre speaker on a console, and an OLED 65’ tv mounted on the wall. As you will observe above this set up, there is no way i can move the centre to where the tweeters of the main speakers are. So essentially, the tweeters from Left to Centre to Right forms a V shape. mid, bottom, mid. The LCR tweeters are not aligned. So you can always tell that the sound is coming from the bottom.

When i moved on to a PJ set up, i wanted to do the same, with a drop down screen and the speakers placed outside the screen at the bottom. but then another member invited me for a quick demo at his place, he told me this, Bryan think carefully, let me play the demo scenes for you when the centre speakers are behind the PJ screen, you will understand what i mean, after that you decide. after i demoed, i was sold! i was convinced, the level of immersion is very different when the speakers are behind the screen instead of being placed at the bottom of the screen. NO matter how, your brains can detect the source of the sound, ie from the bottom.

So i went ahead and built the baffle wall, with centre speakers placed behind the screen. i have been a happy man since, voices tracking on screen action was good. no issues.

Then one fine day (3 days ago), i tested another profile, with the centre turned on. This is one fantastic feature from Anthem AVM90, where you can set up another profile just for this purpose.

this is what it looks like in the controls from the AVM90 :slight_smile:

You can turn this off, and the signal from the centre channel, will now be sent to L+R

Once you have the profiles set up, Phantom Centre vs Actual Centre, you can put the oppo 205 in Loop, and A B the with and without centre to compare… after comparing them, the next post is where i will list down my observations and technical information…

Its worth noting that, there is no harm trying, if you like the approach and it works. go with it. if you dont like it, you can always stick to the centre speaker approach. it has its pros and cons… ill try and list down my findings…

this is a very good subject for discussion… please feel free to chime in…

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Interesting finding can switch profile AB. Nice works there @Ronildoq. Yah v good topic discussion :slightly_smiling_face:

These are based on my personal observations so far…

The Pros

  1. The on screen action voice tracking seems to be superior
  2. There is now depth, layers in the front stage because the mains are away from the wall. vs the centre tucked behind AT and anchored in the middle. there is no room for the centre to create the 'depth" in soundstage
  3. Width is so much nicer, towards left and right. at my home, the width stands at 8m long. with the phantom C, both L+R speakers can extend way beyond what the centre speaker can do in the middle alone. A scene where the crow seems to be flying away to the left, feels like it is flying 30cm to the left and disappears whereas with the phantom, the crow seems to be flying all the way 1.5m to the left and then disappears
  4. Observed that there is no need for Wide Speakers. only 6 super solid speakers required. each will form their phantom image, ie, left speakers with left surrounds will form the width, whilst Left and right will form the centre. Again caveat is if there is only 1 MLP that matters
  5. Save money buying a centre speaker, an amp for it, and cables for it. The money saved, can be channeled towards a better speaker and amp etc. Solid 2 channels
  6. A horizontal centre might not yield the same quality from a tower speakers like your L+R speakers though they can be of the same make.
  7. Clarity. Assuming your LCR is of the same model (always encouraged to use the same LCR for imaging), there is no way a speaker behind a cloth is going to sound nicer than a speaker without a piece of cloth blocking sound. No matter how you eq or adjust the gain, it cannot beat the clarity from a speaker without a piece of cloth in front of it.

The cons

  1. The first problem is imaging. You can only get a good imaging if you sit at the MLP. The moment you move your place to the right/left seat, imaging tend to collapse. It is only ideal if you have a single seat and only MLP matters in that set up. (this is also why i have 2 profiles, family movie time, i switch with centre turned on)
  2. Headroom suffers. Because the mains L+R now needs to take on the signal from the centre at the same time processing signal from L+R on its own. A capable L+R speaker that has ample headroom is nice to have, without which, at louder levels, the mains will start to stress and distort.
    3.If you like the width, to achieve the seat to seat balance, you must use wide speakers. The phantom SL and Left wont work.

Having observed the above, 95% of the time, only that MLP matters. Which is that golden seat you are seated at. i dont think the children will care, or the Mrs will care if vocals are tracking on screen action or not, but people like us, we do. For them, its better than having sound out from the TV. that is my view.

In future demos, ill be happy to demonstrate the difference, A B, you can then hear this yourself and decide if it is worth the effort setting up another profile and to Ditch the Centre channel all together if you have a single MLP, Save money and sounds better! why not ?? Even wondered ?

for me, its very clear… if there is only one MLP, the Phantom Centre is superior compared to the speakers tucked behind the screen . If i had to list down my priorities after AB testing. These will be my priority

  1. Phantom Centre
  2. Centre behind AT screen
  3. Centre outside PJ screen tilted towards ears
  4. Top Bottom Centre speaker to form that Phantom image from top bottom ? Anyone tried this ?? No idea la… so listing it as 4th option
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Lets get down to the technical side of things, what is it actually doing? the attached below is with Post Anthem Room correction up to 200hz only. I only corrected response for bass and left the rest as it is.

the above is what i have measured, first the left speakers, then the right speakers, and finally , channel 3 (centre channel), where the signal is routed by the processor to L+R equally, in Green…

The left and right speakers have been level matched at MLP using a disc from dolby test tones with an spl meter. They measure 65db each, using a 20dbfs test tone with MV set at -20. first thing i have come to notice is that, the levels from phantom C increases by 2db, so Phantom C’s measured output at MLP is 67db. This is normal from the mains when both speakers sum in phase.

But notice above, as it goes past 10khz, the combined output is lowered, there is a gradual roll off about 5db down from 10khz to 14khz. (by the way, i can only hear details up to 14khz, beyond that i cant hear anything)

The above is a common response from speakers, when you play around with the degree of Toe In, the more you toe in, the higher the levels of upper frequencies and the more linear the amplitude response. This is because as you go higher up the frequencies, it is much directional compared to low frequencies where energy is less directional. so that makes perfect sense why the mic is reading a much lowered energy from the tweeters producing the phantom image >10khz. Because the tweeters from the centre image, does not fire directly at the listener position.

So you might have this question , why is the slope >10khz slopes down, but above you are saying it is 2bd louder? which is correct ? The 2db loudness, is derived when we do speaker level matching. When doing speaker level matching, the test tone generators produce energy from 500hz to 2khz. That is why when level matching the speakers for Phantom C, it is 2db louder. and that is why >10khz, it slopes downwards by 5db when it reaches 14khz. Speaker level matching always uses frequencies from these range

Listening test confirms i prefer a downward slope >10khz as compared to a linear target curve >10khz, the speakers sound less bright and fatiguing. I love how it sounds , naturally… without any need to EQ the mains and phantom centre.

How about headroom you ask ? At a 100hz crossover with the MA GX300, it takes up +3db more headroom from each speaker.

So at my place, with a 100hz crossover, i am not experiencing any distortion or notice any stress from the speakers at MV-8. i dont play that loud at MV-5 or reference type of levels. So thank god there, there is no stress from the mains so far.

Another interesting fact is, when blending a phantom centre to the subs, it must be noted that the first two LR speakers must first be time aligned. AFter which, one only needs to blend either the Left or Right speakers with the subs. And bang on, you will get the best blend immediately using ATR. If you measure channel 3 to time align the subs, it will be slightly out.

So bang on time and phased aligned for Phantom Centre with all subs , again adjusting 60cm distance to all subwoofers. (i have shared how to do it on the Anthem thread)

With L+R routing to centre, the timing is slightly off at 50cm distance. So that is incorrect way of blending the phantom centre.

Hope that helps, if you are keen to test this approach, go for it. You might actually like it

Here is one interesting note from Toole’s paper on phantom centre

You will observe the comments that a LR might create a comb filter dip at 2khz.

Nothing of that sort at my place from the measurements …

You can see how linear the decay plot from 100 to 20khz, they decay at 200ms

You can also observe in the amplitude response above, no such cancellation is taking place…

Of course these test were conducted with the centre placed outside the Pj screen.

In my case , I’m comparing the Center speaker placed behind a Projector screen… and from my various demo tracks testing… I just can’t find a single clip where the dedicated centre speaker sounded better than the phantom centre version….

Still exploring… will share along the way if I discover something new

Oh yes, and the above observations are based on the use of a Projector screen.

If assuming it’s the TV in the middle, then a proper dedicated centre might work better. If u have a front left right speaker forming a phantom image in the centre where that large glass panel is placed; not sure how much of those reflection that comes off those tv panels… it can be detrimental to the sound so the experience might be different with a tv

Also I have been pondering the use of the line source speakers, and how that’s gonna sound when used as a phantom.

Studies have shown that line source speakers tend to produce equal SPLs throughout the listening position with very minimal deviation in levels from seat to seat

It’s got the Projectoe screen all the way down, with the line source and line array woofers. Those who know me, knows I’m a big fan of the line array woofers and line source speakers. Very eager to find out… will share my findings

I just love a clean image like the above, a decluttered stage, neat and nice and don’t have to tilt my head looking upwards when watching movies and suffer from neck pain!

And yes, here is another link to AVS forum where some guy spoke about it

https://www.avsforum.com/threads/phantom-center-vs-real-center-for-main-listening-position.3195450/

I have the exact same experience as this guy… nothing to debate …

Here is another good video, one of the users using Seymour screen… I’m also a big fan of the Seymour screens

So something to ponder, another factor when using an AT screen. How much quality you get for sound passing through its material…. At time stamp 3:15 he mentioned the Seymour he is using had minimal effect to sound…

The type of screen material in use makes a difference to some extent …

Super nice the auto masking stuff. One click and done… the auto masking system cost $$… the fabric is a fraction of the cost… shipping goes up exponentially too with dimension…

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So day before yesterday, we continued watching the K-Drama. Some K Dramas are only in 2 channel. So the Mrs was seated to the right, whilst i was seated in the middle. Suddenly she asked me the question, why are the vocals coming from only the right side ? lol… hahahhahaha… She popped the question!!! wahhhhh… Didnt expect her to pop that question… then i realised it was in Phantom centre profile… So i switched on the Dedicated centre profile, and use anthem Cinema logic to upmix content to all channels, much more balanced…

So ya, its obvious… those seated at the side, right or left… will be able to tell that the image shifts to where they are seated… That is the downside with the use of the Phantom Centre…

More information as i dive in deeper…

Lets look at what is happening with all these Phantom Center thing…

The above shows the Amplitude response of Left and Right speakers with a 100hz Crossover, you can observe the gradual roll off after 100hz…with the combined in blue being the Phantom Center when center channel signal i sent through to L+R speakers. As we already know, the phantom image will have lesser energy >10khz, since the tweeters from L+R are not firing at ears (the higher the freq, the more directional it becomes, if you don’t toe in, the higher freq will roll off , known fact). That is established.

if i overlay the Right speaker’s response only, combined with the L+R, you can see how the subwoofers take over frequency below 100hz, that is normal. So far so good.

Remember the first image above, you will notice that the PC, is louder by 2db. but see this above now, not only is the PC louder by 2db, the “Redirected Bass” to the subs is also louder by 2-3db (in my case, 3db). If you compared Right with subs above in second pic, there is no extra 3db redirected bass for the Right channel. But, there is additional +3db more from the redirected bass with the center channel.

I decided to check this because i noticed, the bass from the center is a bit midbass heavy… due to this re-directed bass from the center channel. (since 70% of HT content is with Centre speaker, so 70% of redirected bass is also from center)

If you use a dedicated center channel, you will not see this +3db redirected bass boost. Instead, it will look more like the pic in 2

Finally, lets see the 4th image, which shows us, L+subs, R+subs and PC+sub. Immediately you will see that PC+subs is louder by 3db <200hz, and the tail at the back >10khz, is reduced in levels…

This is how the Phantom Center works for HT, if you take this path. You need to be aware, the phantom center channel is now louder by 2db, and the re-directed bass to the PC is louder by 3db

To strike a better balance, i have actually lowered the Left and Right speakers to about 64.5db each with a 40dbfs tone. (105 is reference) so i get a summed Phantom C that is approx 66.2db from the PC. not too bad, much more balanced

I am still exploring this PC and i find this to be very impressive in my case.

The first thing i noticed is, if you see the “C” that is where the center speaker is located. when i use the Phantom Centre, the Left speaker is able to “Extend” the image all the way to the left, where as the center speaker extends up to the location of the left speakers. Damn solid the Phantom center, when you have the space for width…

Then if you see this above, between the mains left speaker to screen, there is a 1.1m depth. and the baffle wall is about 45cm thick. with the Phantom C, i can get layers of depth in vocals within this 1.1m distance between the AT screen and LR speaker’s tweeters. The dialogue tracking is 3 dimensional like, just like music. I never knew you can achieve that kind of quality with Home Theatre. On the contrary with a dedicated center, since it is stationary behind the AT screen, the voices are anchored on screen and it is less 3D like. There is no chance for the center speaker to create any type of depth because of its location. So image tracking is not as solid as the Phantom C

ON “you cant handle the truth” demo, tom cruise will walk forth and back as he questions jack nicholson in the courtroom. that scene is very obvious as he turns his back and faces the jury, then walks back to question the colonel, to and forth… the layers of depth for vocals happening in that 1.1m depth area were magnificent… …This kind of effect is irreplaceable and can only be achieved with speaker placement

In the past, i have always had that mentality, how to beat a dedicated center speaker ? there is no way you can beat a dedicated center speaker for HT… how wrong i was… and im not afraid to admit i was wrong…and i paused a while, if center is so good and it has so good extension, why do people need LR speakers for music ? After all, vocals are coming from the center with instruments separation, so wouldnt a single center speaker do the job for music ? thats the fun part about this hobby…

After this experience, i realise 1 thing. and im quite clear, we only need 6 very solid speakers with solid amplifier driving them. ill still keep the centre speaker inside, for family movie time. but if i do take that upgrade path, ill look for one with good width and depth dispersion. The magnepans come to mind…

With the addition of the AVM90 into the set up, i am starting to appreciate the benefits of a quality speaker now…

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To have better focus on Phantom center channel, the best is have a further MLP or close up the distance between L&R speaker while MLP position remain to have a minimum sound shift while listening to phantom channel.
The front stage behind equipment and speaker need to be well damp will help to improve the centre image with or without a center channel.

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Interesting….