Can a center channel improve stereo music?

[juliangst]

While planning my surround sound setup I got stuck at the questions if I want to get add a center channel or not.

For movies and native surround music like Dolby Atmos music a center channel makes absolutely sense because there is native content mixed to that channel.
But most of my music still is stereo and I don't know if the center will improve the sound enough or at all to justify spending money on a center channel.

I would upmix all my music using the Dolby upmixer and activate center spread.

In theory the center channel would help with the center imaging and anchor the sound to the middle.
A phantom center should also be a lot worse than an actual center when considering the HRTF.

How large are those effects in the real world when using the dolby upmixer and center spread?
The center channel would also be a bit lower than L+R because of the TV which could possibly make the sound worse because of the lower height.

 

[gene_stl]

You might get a more informed answer to this particular question , over at https://www.quadraphonicquad.com/forums/whats-new/posts/3851657/

 

[DVDdoug]

You won't be listening "as intended" and it's hard to predict if you'll like it or not.

I generally like to use a "hall" or "theater" mode to get delayed reverb out of the back speakers, giving the impression of a larger space. I don't notice sound coming out of the center in those modes but I haven't carefully checked it out.

I don't know what "center spread" does but it seems like the opposite, spreading the center channel out to the sides. But with stereo you don't have a center channel.

 

[juliangst]

I don't know what "center spread" does but it seems like the opposite, spreading the center channel out to the sides. But with stereo you don't have a center channel.

When upmixing without center spread all the correlated information gets dumped to the center channel and you lose a lot of sound stage width because your L and R don't do a lot anymore.
Center spread keeps that content on the L+R while the center channel plays correlated information at a reduced level. It's the go to feature everyone uses when upmixing stereo and I would do that as well

 

[hnash53]

I have a 3.1 system. When listening to music I always switch "stereo." If not, the center channel "steals" most of the music from the L & R and the stereo effect is lost.

 

[Martin]

When I listen to music on my 7.2 system (usually on YouTube) I always listen in stereo + subwoofers. I dislike music through a center channel and abhor fake surround sound formats.

Martin

 

[Slayer]

While planning my surround sound setup I got stuck at the questions if I want to get add a center channel or not.

For movies and native surround music like Dolby Atmos music a center channel makes absolutely sense because there is native content mixed to that channel.
But most of my music still is stereo and I don't know if the center will improve the sound enough or at all to justify spending money on a center channel.

I would upmix all my music using the Dolby upmixer and activate center spread.

In theory the center channel would help with the center imaging and anchor the sound to the middle.
A phantom center should also be a lot worse than an actual center when considering the HRTF.

How large are those effects in the real world when using the dolby upmixer and center spread?
The center channel would also be a bit lower than L+R because of the TV which could possibly make the sound worse because of the lower height.

IMO, only you can answer as to whether or not you may like it. Using a center channel for music, would simply come down to personal preference.
However, I do think it degrades the whole stereo image when adding a center. After all, stereo music is two channel audio.
Personally, I have never felt the need for a center channel, when listening to my music.

 

[juliangst]

IMO, only you can answer as to whether or not you may like it. Using a center channel for music, would simply come down to personal preference.
However, I do think it degrades the whole stereo image when adding a center. After all, stereo music is two channel audio.
Personally, I have never felt the need for a center channel, when listening to my music.

But why would it degrade the stereo image if it just plays correlated signals and leaves L and R as they are?

I can understand that it might not add much to the experience but in theory it should be better than just two speakers.

 

[NTK]

Upmixing from 2-channel to multi-channel is very tricky.

Say, you have a sound panned half way between center and right. In the 2-channel recording, the sound will be in both left and right channels. It's magnitude in the left channel will be lower than the magnitude of the right channel, or alternatively it can be done through a time delay panning (as in recordings using spaced mics). The mathematical relationship between the strengths/timings in each channel to perceived position by the listener is the "pan law". (You need to know this pan law if you want to extract the location of the sound, and the pan laws we know of are far from perfect.)

Now, if you are adding a center channel, and do not want to upset the location of the sound. The upmixer will have to intelligently extract the sound from both of the original channels, computes its direction (directional decoding), and redistribute it to the 3 or more channels. The ideal goal is to remove it completely from the left channel, and reproduce it by distributing the sound to the center and right channels only, based again on the pan law (possibly a new pan law for 3 front channels).

If you simply get the center channel by summing the left and right channels, for example, the hard panned sounds (those sounds present originally in only the left or right channels) will "leak" into the center channel, and will therefore causes the sound images to shift closer to the center and the sound stage to shrink.

You can probably guess that successful or correct directional decoding is not guarantied and there are a lot that can go wrong with this process.

 

[juliangst]

But can't Dolby or Auro3D upmixers already do that?

 

[NTK]

But can't Dolby or Auro3D upmixers already do that?

Yes. With varying levels of success.

 

[Jon AA]

But why would it degrade the stereo image if it just plays correlated signals and leaves L and R as they are?

In my experience it doesn't. But the only current upmixer that works that way is Auromatic (which may be why it is so widely preferred for music listening). It leaves the L&R signals untouched. It copies the common material between them and places that in the center channel, as well as copying the decorrelated (out of phase) material and sending it to the surrounds. By doing that but leaving the signals in the L&R untouched, the imaging and soundstage never seems degraded or altered to my ear at all, only "enhanced." *

DSU, with center spread on treats the center more similarly to Auromatic and is certainly better than extracting (deleting them in the L&R) all the common information from the L&R and dumping it into the center channel as it does with center spread off, but it still quite aggressively extracts decorrelated signals from the L&R and sends them to the surrounds which has more of an effect of wrapping the soundstage around the listener. Some may like that better, some may not and for many it depends on the source material as to which they prefer.

* This excludes "Movie Mode" in Auromatic, which I understand does do some extraction (as you would want with movies) but I haven't tested it.

 

[Gringoaudio1]

Rarely is a matching centre speaker as good as the main left and right set. Why unload content from your excellent main speakers into a fair centre speaker? My experience anyway. Sonus Faber Venere 3.0 surround system and the centre and surrounds are pretty fair compared to the Mains.

 

[juliangst]

Rarely is a matching centre speaker as good as the main left and right set. Why unload your excellent main speakers into a fair centre speaker? My experience anyway.

I obviously would not go with a cheap 100€ center combined with some high end towers.

The setup I plan to do is Kef R3 Meta with the R2 Meta or maybe R6 Meta center. They all have the same state of the art performance. Bass extention isn't too important with some subwoofers

 

[valerianf]

"If not, the center channel "steals" most of the music from the L & R"
There is a workaround to send more sound to the FR and FL: Dolby music with center spread.
Using a Dolby Pro Logic II it is working very well as you can customize the effect.
With the newer AVR, only a few can have the center spread adjusted: the latest Onkyo have it.

Another important point is that the center need to be in phase with FR and FL.
A room correction is needed and the result will depend how the passive crossovers are designed.
If all is set properly the result is enjoyable, even in 5.0 configuration.

 

[jae]

But why would it degrade the stereo image if it just plays correlated signals and leaves L and R as they are?

I can understand that it might not add much to the experience but in theory it should be better than just two speakers.



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If stereo audio is produced competently in a proper environment we can assume whatever deleterious or contributory effects of reproducing sound in this manner are already adequately compensated for in the production process by virtue that production is also using a stereo setup with these same "issues"- and the final result of their work is what they are intending you to hear. So in regards to "improving" reproduction of stereo content I would say whatever potential juice that may exist is not worth the squeeze. For stereo, time/dollars should be spent on better/different speakers or fixing the room.

 

[kiwifi]

I mostly listen the music using Audyssey/Marantz multi channel stereo, which outputs to all channels, including the center. The center is output at reduced level compared to the other channels in this mode, but I would prefer it to be off completely.

I have been considering eliminating my center channel speaker from my 7.4 system, to possibly (?) improve the stereo separation in multi channel stereo mode. I assume that if I did, movie (Dolby) center channel signal would simply go to the L/R in equal measure and create a phantom center channel.

 

[restorer-john]

I mostly listen the music using Audyssey/Marantz multi channel stereo, which outputs to all channels, including the center. The center is output at reduced level compared to the other channels in this mode, but I would prefer it to be off completely.

I have been considering eliminating my center channel speaker from my 7.4 system, to possibly (?) improve the stereo separation in multi channel stereo mode. I assume that if I did, movie (Dolby) center channel signal would simply go to the L/R in equal measure and create a phantom center channel.

Try it. Unless you are sitting way off to one side, I'll bet the overall presentation will be more enjoyable.

 

[fpitas]

If stereo audio is produced competently in a proper environment we can assume whatever deleterious or contributory effects of reproducing sound in this manner are already adequately compensated for in the production process by virtue that production is also using a stereo setup with these same "issues"- and the final result of their work is what they are intending you to hear. So in regards to "improving" reproduction of stereo content I would say whatever potential juice that may exist is not worth the squeeze. For stereo, time/dollars should be spent on better/different speakers or fixing the room.

I agree. If the phantom center isn't working correctly, fix that.

 

[AdamG]

Since you need a center channel for Movies and music produced and mixed specifically for multichannel, the answer is yes and no. Your AVR will give you all sorts of listening format options. You can choose whatever format you like best. There is no technical answer right or wrong. Entirely up to you. Listen to what makes you happy.