Can a center channel improve stereo music?

[gnarly]

I have had great success adding a center speaker for improving stereo.
My system is for audio only and uses three identical speakers for LCR, with each speaker having the same subwoofer.

Feeds for LCR come from a matrix processor that can implement matrices such as shown by Elias Pekonen http://elias.altervista.org/html/3_speaker_matrix.html
All forms of LCR matices I've seen so far, use some degree of subtraction L&R from one another, for deriving the new left and the new Right.
And use some degree of L&R addition for deriving the Center.

Which type of chosen matrix works best on any given track, is pure listen and see ime. My processor allows switching between how many I'm willing to load into it.
That said, if I had to choose one matrix, it would probably be one of a energy preserving Gerzon-type implementation.
I've only looked at Gerzon's older work that was meant for audio rooms, but i've seen he put out a paper in 1990 about 3-channel more specifically for home-theatre http://www.audiosignal.co.uk/Resources/Three_channels_USL.pdf

Anyway...what does my LCR rig bring to the party over stereo?
Well, let me first say, I judge audio quality by what I hear outdoors. Either mono or stereo, but most often mono for ease of setup.
The clarity/detail/timbre of outdoors greatly exceeds anything I've heard indoors.

BUT, of course it lacks the room envelopment of indoors.
So, envelopment is gained indoors, but at expense of clarity......particularly with regard to stereo's phantom center, which seldom comes even close to outdoor clarity, ime.

Hence my goal with 3-speaker indoor LCR...get back outdoor clarity and have envelopment too.

It plain works ime....greatly improved center image, and still with envelopment too. Various matrices can trade one attribute for the other.
It's the most enjoyable, clearest indoor sound I've heard yet.

The biggest caveat ime, is that songs really react differently to it; and as said, to particular matrices that make the tradeoff described.

Sometimes, plain ole stereo can't really be improved on. Unfortunately, not often enough imo.
Shows me just how very differently tracks are mastered and there's no such thing as one shoe fits all.

 

[sarumbear]

I personally don’t believe stereo sound will benefit from anything other than using two speakers. Any extra speakers are always added using a process, which is created to someone’s decision and to satisfy their taste. You may like the sound but you are moving away from the original. There’s nothing wrong with that though. As long as you enjoy, everything is good.

However, if the aim is Hi-Fi, I believe nothing should be added to the signal chain. Otherwise, why are we measuring amplifiers and speakers to see if they are flat?

 

[juliangst]

I don't think any kind of upmixing is against the aims of high fidelity.
With upmxing you aren't changing the original track you just redistribute the sounds.

 

[gnarly]

I personally don’t believe stereo sound will benefit from anything other than using two speakers. Any extra speakers are always added using a process, which is created to someone’s decision and to satisfy their taste. You may like the sound but you are moving away from the original. There’s nothing wrong with that though. As long as you enjoy, everything is good.

However, if the aim is Hi-Fi, I believe nothing should be added to the signal chain. Otherwise, why are we measuring amplifiers and speakers to see if they are flat?

Unless stereo is as simple as one mic feeds the left channel of the recording, and another mic feeds the right channel of the recording...with no crosstalk/ channel mixing whatsoever...
...seems to me any further "stereo" in the recording .......has already been artificially added into the signal chain.

Most all Stereo itself deviates from Hi-Fi, right from the gitgo....

Nothing sacred here, that can't be improved on to taste....imo/ime

 

[sarumbear]

Unless stereo is as simple as one mic feeds the left channel of the recording, and another mic feeds the right channel of the recording...with no crosstalk/ channel mixing whatsoever...
...seems to me any further "stereo" in the recording .......has already been artificially added into the signal chain.

Most all Stereo itself deviates from Hi-Fi, right from the gitgo....

A stereo track is how the artist heard and approved it. It has nothing to do with the way it is captured. It is to do with how it was aimed to be consumed.

Nothing sacred here, that can't be improved on to taste....imo/ime

Which is what I said. Maybe you missed the following sentence on my post.

As long as you enjoy, everything is good.

 

[sarumbear]

I don't think any kind of upmixing is against the aims of high fidelity.
With upmxing you aren't changing the original track you just redistribute the sounds.

How do you do that? How can you extract individual sounds from a stereo mix? Unless you use an AI process like Peter Jackson used on the film Get Back or like Giles Martin used on Revolver 2012 remix all upmixes alter the tonality of the original sound as they use filters.

 

[gnarly]

A stereo track is how the artist heard and approved it. It has nothing to do with the way it is captured. It is to do with how it was aimed to be consumed.


Which is what I said. Maybe you missed the following sentence on my post.

Yes, you did say all is fine with whatever is enjoyed. My bad for thinking i needed to repeat it.

I can't give any credence to the idea of a track being what an artist heard and approved;
and that replicating the artist's experience/approval is/should be, the goal of Hi-Fi.

How much control does an artist even have in the recording process ?
Probably everybody's primary goal involved with producing a recording is to make a buck. Highly likely the artist's major goal too.
So the idea of artistic intention and approval ruling the process over all that of all the invested production partners.......seems pretty much a fairy tale to me.
For the most part, I think they're all mainly picturing what will sell.......

 

[Sancus]

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.

The deleterious effects of phantom center aren't "fixed" so you can't simply EQ them out or whatever, because the degree varies based on the setup, listening distance, etc. Phantom center just sounds worse than real center, that's all there is to it. Nothing you can do about it.

 

[juliangst]

The deleterious effects of phantom center aren't "fixed" so you can't simply EQ them out or whatever, because the degree varies based on the setup, listening distance, etc. Phantom center just sounds worse than real center, that's all there is to it. Nothing you can do about it.

Can upmixing to 3.x fix those cancellations?
That’s main reason why I wanted to get a center channel.

 

[Steven Holt]

I strongly suggest that you take AdamG247's advice. Once you start trying to go beyond 'good enough', you're wading into dark, murky waters.

 

[AdamG]

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.

How much do you watch Movies and Tv Shows ? The Center channel is the single most important speaker in a home theater setup (maybe tied with a Sub or two). From multiple articles written about home cinema audio mixes. Approximately 60% of the sound for a movie or tv show is directed to the Center channel speaker. Don’t skimp here or you will regret it. Get the biggest and best center channel speaker you can afford and thank me later. Or go cheap and buy another better one later when you can’t hear the dialogue. I have done the phantom center thing and it does not compare to a real center speaker. Not even close. JMHO after all….

 

[juliangst]

How much do you watch Movies and Tv Shows ?

Not enough that it would justify getting a center channel for movies and shows alone.

I would say it’s 90% audio consumption and 10% video consumption.
90% of video consumption is YouTube which is stereo only and out of all my music 5-10% is Dolby atmos music.
So in total ~5% of the content is consume is multichannel

 

[sarumbear]

How much do you watch Movies and Tv Shows ? The Center channel is the single most important speaker in a home theater setup (maybe tied with a Sub or two). From multiple articles written about home cinema audio mixes. Approximately 60% of the sound for a movie or tv show is directed to the Center channel speaker. Don’t skimp here or you will regret it. Get the biggest and best center channel speaker you can afford and thank me later. Or go cheap and buy another better one later when you can’t hear the dialogue. I have done the phantom center thing and it does not compare to a real center speaker. Not even close. JMHO after all….

The title of the thread is the use of centre speaker on stereo “music,” where the speaker is fed via a sound processor (up mixer). I think the use of a physical or phantom centre speaker used for a multi-channel film soundtrack is a different discussion.

 

[Jon AA]

Another important point is that the center need to be in phase with FR and FL.

That's a very good point--the LCR need to be time aligned very well or you will hear it for any of the upmixers where material is in all three. This is also why none of the upmixers will do as well for off-axis listeners as when the material is mixed to the center channel in the recording in the first place. A native multichannel where the vocals are placed in the center (but much other dual-mono content is left in the L&R) is always going to be better, placing the vocals where they should be for all listeners but not collapsing the soundstage.

 

[juliangst]

Another question abouth the phantom center frequency cancellation: Can't we just use FIR/ all-pass filters to change the phase in the problematic frequency region so that the cancellation doesn't occur?

 

[juliangst]

I also just did a few tests with pink noise and 1kHz and 2kHz tones and the cancellation effect is pretty substantial with certain angles.
When moving the head sideways or rotating the head there are large changes in timbre or complete cancellations at the position of one ear.

 

[Jon AA]

I don't think any kind of upmixing is against the aims of high fidelity.
With upmxing you aren't changing the original track you just redistribute the sounds.

Unless stereo is as simple as one mic feeds the left channel of the recording, and another mic feeds the right channel of the recording...with no crosstalk/ channel mixing whatsoever...
...seems to me any further "stereo" in the recording .......has already been artificially added into the signal chain.

Exactly. In much stereo content (the stuff that works best for upmixing IMHO), the stereo track has already been heavily processed in order to downmix it into a stereo mix in the first place.

Consider and orchestral recording for example, where multiple mics are used. Some of those mics will not be pointed at/located near the stage, they will be out in the audience area, recording the reverb/ambiance/"sound of the venue." It's ridiculous to think those sounds should be coming from in front of the listener for "high fidelity." Quite the opposite in my opinion. But when you're limited to 2 channel, they must be downmixed into the mix such that they do, in fact, come from in front of the listener. Putting them in the mix out of phase may "trick your brain" on playback a little such that it seems like they are coming from around your room, but in my experience that's never even close to as good as actually playing those sounds from real speakers located around the room.

How do you do that? How can you extract individual sounds from a stereo mix? Unless you use an AI process like Peter Jackson used on the film Get Back or like Giles Martin used on Revolver 2012 remix all upmixes alter the tonality of the original sound as they use filters.

Uhm, I'm not sure what you're asking here. Extracting individual sounds from a stereo mix is exactly what upmixers do. Are you unaware of how they work?

 

[ocinn]

One of my neighbors when I lived in the South was an extremely eccentric engineer and had this elaborate analog system that subtracted the "common" signal from the L and R, and sent it to the center, and then sent only the difference signals to the L and R. His was incredibly well implemented and had a lot of thought put into it, but I believe you can do something similar with 2x APT Holman pres.

3x Technics SB9500s, infinite baffle ceiling subwoofers, in a 30x40ft room (more like a studio), fully treated and beautiful (speakers were lit with architectural lighting, etc). MLP was ~35ft away from speakers.

Was one of the most visceral and real listening experiences I've ever heard, and I work in the concert/events industry/live sound.

It was only then that I finally understood why the dude demolished 80% of the interior of his unkempt falling-apart house and slept and worked in his kitchen just to have access to that system.

 

[gnarly]

One of my neighbors when I lived in the South was an extremely eccentric engineer and had this elaborate analog system that subtracted the "common" signal from the L and R, and sent it to the center, and then sent only the difference signals to the L and R.

Yep. Although I don't think using only the differences between L&R, to L and Right would work well....unless the common signal was split into some high pass and low pass elements.

Here's an example of one of the matrices I employ for LCR . (snipped from the Elias Pekonen link in #26)

The 35 degree angle is between listener and speaker...so a 70 deg wide angle between speakers.
Every listening angle setup gets a different set of matrix coefficients..
Anybody at all interesting in 3-ch should check out Elias's pages...

Was one of the most visceral and real listening experiences I've ever heard, and I work in the concert/events industry/live sound.

It was only then that I finally understood why the dude demolished 80% of the interior of his unkempt falling-apart house and slept and worked in his kitchen just to have access to that system.

haha too funny !!

I get accused of being a bit eccentric too.... thank providence for a beautiful wife that helps me defend this DIY mess to guests!

 

[AdamG]

thank providence for a beautiful wife that helps me defend this DIY mess to guests!

She is most definitely a Keeper!