Now That Atmos Is Everywhere… Real vs. Phantom Center in a 5.1 Music-Focused Setup

[Newman]

The excuse that a center-only vocal is worrisome/too exposing to some artists has circulated for years, well before Atmos. I have to think it has some basis in truth.

Me too. I believe that it is the reason why DSU has a 'Center Spread' option, which I take to be tacit acknowledgment that the concern is real.

OTOH the very existence of DSU Center Spread illustrates that the concern (with Atmos recordings) can be dealt with, in the production stage, by much more nuanced methods than abandoning the centre channel, and which might not have some of the other sonic disadvantages (see my earlier posts) of abandoning the centre channel for music. DSU CS seems to reduce centre channel output only by ±5 dB, so maybe the centre channel's less coloured tonality (compared to a phantom centre) is retained, maybe people in off-centre seats aren't having the whole centre image collapse into one speaker like they so often experience with no centre channel.

BTW I am unaware of any formal testing on the subject of the two 'maybes' in the previous sentence.

cheers

 

[TK_IIVI]

* and btw, I would be surprised if the issue of comb filtering from phantom centering ever enters the consideration of mixers or artists. I'd like more testimony on that too

I think that was one of the things brought up by one or more mix engineers in one of the videos in this thread actually.

Another thing is, vocals are NOT the only discrete element one finds in the C channel of multichannel mixes. In my experience, bass guitar parts show up there, along with more transient effects (obviously including sounds that pan across the front stage.)

Sure, and nobody has to do anything in a single particular way. A mix engineer can absolutely pan some of the signal into the center instead of 100%, which they can do for more than just vocals.

I think vocals likely are "special" because they are driving the story in traditional song writing and are very often associated heavily, or exclusively, with "the artist". Even a group like AC/DC for example will be though of as Brian Johnson 'and that rhythm section'. With the spotlight so heavily on the lead vocals its no wonder scrutiny of that one instrument is higher than the rest. As for bass I find the more "questionable" isolation is whatever drives positioning and "clarity" the most, which is probably above a certain frequency. So bass in the center isn't really a problem, probably not even if it's distorted since we perceive it with the lower frequencies.

 

[krabapple]

Perceived sound of bass/electric bass is surprisingly strongly influenced by upper harmonics . And in most modern systems, the low fundamentals up to 80Hz will go to the subwoofer (that spans the fundamentals of the open E, A, and D strings)

Either way, I don't think bass wholly in the center is a problem...nor vocals. As long as it sounds good in the mix*! I was just noting that centering an part isn't confined to lead vocals, at least in the (mostly 5.1) mixes I've analyzed.



*also, selfishly, I'm happy to have an isolated bass part if I want to learn it.

 

[Sal1950]

Either way, I don't think bass wholly in the center is a problem.

It more or less has to be, and has been for decades for a vinyl pressing.

 

[Oddball]

The excuse that a center-only vocal is worrisome/too exposing to some artists has circulated for years, well before Atmos. I have to think it has some basis in truth. The thing is, it could be just experience with one or a few extremely famous singers (e.g., a Mick Jagger, a Taylor Swift) driving that narrative, rather than a general trend. How are we to know? More testimony from more mixers who've gotten that feedback, is the only way.*

Another thing is, vocals are NOT the only discrete element one finds in the C channel of multichannel mixes. In my experience, bass guitar parts show up there, along with more transient effects (obviously including sounds that pan across the front stage.)

In at least one lazy 5.1 I own, the Center is literally just a very low level replicate of front L/R (Nektar's Remember the Future SACD, which was clearly just an indifferent 6-channel upmix of an old quad source. The Jeff Beck Blow By Blow SACD is a similar 4ch-->6ch upmix.)


* and btw, I would be surprised if the issue of comb filtering from phantom centering ever enters the consideration of mixers or artists. I'd like more testimony on that too

Comb filtering is a bit different. It occurs when same signal is reproduced from two sources that are not independently EQd. In phantom center scenario they would be independently EQ'd so arguably, combing should be mitigated.

What really happens here is a combination of (some possibly residual) combing and different FQ response from L/R speaker. Taking into account phase, timing and other goodies that might come to play, odds are even worse that this is a good option. Can't expect the sum of L / R to be the exact as the center would be, even in the sweet spot. I have no idea how close or far off this response could be as it is individual to room and setup. So some might have it better and some worse.

Now that Atmos is everyware, you can fake it or get a proper center channel. Not a deal breaker, but thinking of phantom setup as ideal is definitively not the case.

 

[Mort]

Even a group like AC/DC for example will be though of as Brian Johnson 'and that rhythm section'.

That's a reach. Your point about vocals usually stands, but Angus Young is probably better known.

 

[TK_IIVI]

That's a reach. Your point about vocals usually stands, but Angus Young is probably better known.

That's plausible.

 

[Sal1950]

I did sent a couple emails to Kaleidescape asking then to consider starting a "Audiophile Music" tier to their system. If I could listen to and download any album to my server and wouldn't have to purchase the BluRays any more, I wouldn't mind paying them a little more.

Just an FYI, I recently contacted Kaleidescarpe again asking them to add a high quality music tier to their streaming service to include lossless Atmos (TrueHD or better) and multichannel files. I got this response a couple days back. A bit disappointing for sure but I know we didn't get lossless 2 channel or any Atmos at all without a bit of nagging, begging and cajoling. We only need to keep up the good fight.

"Hi Sal,
Thank you for the suggestion. If we were ever to consider adding a music component back to Kaleidescape systems, I'm sure we would look at all premiere formats. At this time, there is no plan to add music to our catalog, outside of the concerts that we currently have.
Regards,
André"

 

[EJ3]

People here seem to have very thin, sensitive skin. Jesus!

Now there is something that I surely agree with you on!

 

[Andysu]

Comb filtering is a bit different. It occurs when same signal is reproduced from two sources that are not independently EQd. In phantom center scenario they would be independently EQ'd so arguably, combing should be mitigated.

What really happens here is a combination of (some possibly residual) combing and different FQ response from L/R speaker. Taking into account phase, timing and other goodies that might come to play, odds are even worse that this is a good option. Can't expect the sum of L / R to be the exact as the center would be, even in the sweet spot. I have no idea how close or far off this response could be as it is individual to room and setup. So some might have it better and some worse.

Now that Atmos is everyware, you can fake it or get a proper center channel. Not a deal breaker, but thinking of phantom setup as ideal is definitively not the case.

dave rat makes the complex sound , sound logical , comb my hair yeah that finger comb fingers though the hair and animals moooing

 

[Duke]

Perceived sound of bass/electric bass is surprisingly strongly influenced by upper harmonics.

Agreed.

... also, selfishly, I'm happy to have an isolated bass part if I want to learn it.

Are you a bass player?

... vocals are NOT the only discrete element one finds in the C channel of multichannel mixes. In my experience, bass guitar parts show up there, along with more transient effects (obviously including sounds that pan across the front stage.)

While phantom center mode doesn't get much love around here, I'm not convinced that phantom center mode necessarily results in significant coloration.

My understanding is that the perception of coloration from stereo's 2 kHz comb filter dip goes away when you have a spatially-accurate phantom image.

It has been shown that, as the ability to detect a spatial image improves, the ability to detect a timbral coloration (or at least one due to comb filtering) decreases. In this video clip Francis Rumsey describes this phenomenon, which he calls "decoloration". The relevant part starts about 15:20 and goes to about 21:40: