Don’t forget the kitchen speaker. If it was in sync, you would also hear the other speakers from the Kitchen, so all of this would distort the ‘effect’ the Sony Amp is trying to synthesise.

I noticed no degradation of the sound stage/image caused by a single play 1 in the centre. Of that I am certain, ymmv. No improvement either. So I put it away.

As to the second para quoted, I can not comment, never having heard the outcome. But I doubt I will pursue that even if available, since my Quad pair does all that I need for good stereo sound in the space.

I can buy the argument for Trifield in a situation where listeners are off-axis. Where one is on-axis -- the ‘sweet spot’ -- adding a further transducer is likely to do more harm than good IMHO, given the need to maintain phase coherence and so forth. Certainly in any critical music listening I never feel the need to further anchor central sound images; they’re already there and pin-sharp.

I think this will depend on where the listening position is, when not ideal  in terms of the distance from the speaker plane. Where closer than ideal, this Trifield thing will help imaging where without it there may be a hole in the image at the centre. But where further than ideal, as is the case at my end with the listening distance to the speakers more than the distance between each speaker, it won’t make a difference.

All I can talk from is my experience. I have 3 different systems in 3 different rooms. All are based on Meridian surround sound processors. All 3 started off as simple 2 speaker systems. Once I moved onto watching DVDs on one system and upgraded it to surround sound, there was no going back. Music, speech and everything else just sounds more convincing and lifelike.
Even on my office system which has a far from ideal speaker layout - my head is about 0.75m from the centre speaker - I enjoy the listening experience. 
But then I’m a ‘practicalist’ rather than a ‘purist’!

I’m not sure you can really call doing DSP to covert stereo signals to 3 or more signals always, even when it causes syncing issues in multiroom audio, as practical. 

I’m not sure why you think this isn’t practical? There are any number of AV amps out there, running in price from not very much up to many thousands of pounds, that that are all capable of doing the job.

For me there are a couple of things here;

1. Stereo signals encode a wide sound stage into left and right channels. The volume of any particular sound source e.g. a singer, or a guitar or a cymbal, is varied between left and right channels to represent its position between a nominal stage left and stage right. That is simply how the spatial position is coded into the ‘stereo’ signal.
2. The simplest way of reproducing the sound stage is to feed the left channel through an amplifier to a speaker on the left and the right channel to a speaker on the right. A basic ‘stereo system’. This works Ok as long as the listener is sitting exactly equidistant between the speakers and both speakers are capable of reproducing the full audio frequency range.
3. Each musical instrument, singer or other sound source is basically a single point source. Therefore if you can analyse the ‘stereo’ encoded sound stage signal, work out where each sound source sits on the sound stage and feed its signal to a speaker at the equivalent point on the listening sound stage then you will get a reproduction of the sound stage that is less dependant on listener position than having just 2 speakers. The listener feels more that they are ‘in the sound stage’
4. Given the trivial cost of computer processing power these days, the only practical limitation to having multiple speakers across the reproduction sound stage is the cost of the amp and speaker for each location. Technically any number of speakers is possible.

If it is possible to have a better sound reproduction system in one room, and you are prepared to pay the money for it, but you don’t want/need that in acoustically adjacent rooms, I really don’t understand why people are throwing up objections to a slight tweak to the Sonos system that would make it possible.

If a particular individual is happy with a simple 2 speaker stereo system then that is perfectly OK. But there are audibly better solutions in existence. It seems perverse to me that people who haven’t experienced those better systems are arguing that a simple software fix that would enable basic and more advanced ‘stereo’ delivery implementations to work together in harmony shouldn’t be implemented.

I suppose that is why personally I use ROON with Meridian surround sound kit. I’m very happy. Its just my neighbour who is suffering having splashed out on a Sony AV amp for his lounge and Sonos to feed all 5 rooms.

1. I can understand a six speaker set up with each speaker fed a signal corresponding to each sound source - but what happens then if there can be only one centre speaker convenient to deploy? Re-encode the stereo signal for that situation?
2. I don't think people are throwing up objections - they are suggesting that the market for such a solution may not be large enough to be of interest to Sonos.

Ah, the good old “surely it’s only a few lines of code”. Which simple software fix was that? Delaying a Sonos zone that’s grouped with an AVR, or implementing Trifield in Sonos itself? 

Leaving out the Sonos side of things, at least this sounds more interesting than the Hi Res nonsense. But I can’t see myself deploying six front speakers. And even if I could, for my use case where the speakers are about six feet apart, while the usual listening area is eight to nine feet away, I find it hard to imagine that a 6 speaker front will do better imaging than the stereo illusion from the speaker pair. Or even coded music for just an extra speaker at the centre.

Now if the listening was four feet away for the same speaker set up, I can see a centre speaker adding audible value.

I’m not sure where this idea of 6 front speakers has come from. I’ve only talked about an extra centre speaker fed by the common parts of the left and right stereo channels. 

As for wether the extra channel is worth it, its down to personal preference just like all listening comparisons. As I write this I have just experimented with my office system where I am very close to the front speakers.

With my Meridian surround processor set to Direct mode, the singer’s voice appears to move towards whichever of left or right speaker my head is closest to. This is what you expect from a simple 2 channel stereo reproduction system.

However, if I set the Meridian to Trifield then the singer’s voice remains rooted to the centre of my desk. Instruments etc, tend to stay on the side they are intended to be e.g. bass guitar towards one side. This is a sound stage that, to my ears, provides a better located and more continuous sound stage than basic 2 channel/2 speaker reproduction. But that is only my perception garnered by actually listening to the setup.

Six speakers came from the words in italics, as an illustrative number. Because the sound stage does not consist of just three sound sources either - left/right/centre - as the word in italics implicitly accept. If 2 speakers are not enough, neither are 3.

As I already said, because it’s causing sync issue with your multiroom system.  I get that DSP manipulation of stereo audio is common, regardless of whether that be converting to 3 channels, 5, or whatever.  I don’t see it as practical to expect Sonos, or any other multiroom audio system really, to allow users to manually tweak delays in any or all speakers in the system to accommodate processing on external systems.

As an aside, I find it interesting that music in never produced in 3 channel audio.  Two channel, 5.1 for a while, and now atmos music.   With the amount of homes that now had LCR setups and/or soundbars, seems a little surprising.   Also, many new cars come with a center channel for audio, even though they only have 2 channel sources.  Granted, this is because the manufacturer can use cheaper speakers while giving the impression to customers that they are getting a better audio system worth paying more for.

On the other hand, if a centre speaker does the job of anchoring the singer to the centre, I strongly suspect that my “cheap” solution of adding a play 1 between the Quad pair would also do that just as well. As I said, I only ran my trial where the listening position was further away from the ideal one, so this was not noticeable because there was no hole in the centre to start with. I might just try to run the test again some day, and see if the usual consequent hole in the centre of the image when closer to the speaker plane than ideal, is filled in by the play 1. I suspect that may well prove to be the case. 

It will still be of no real value to me, because with my listening position further away from the equidistant ideal, there is never any hole in the centre of the illusion created by just the speaker pair. Even if I move a little to the left/right of the listening area.

As I understand it, the filling in of the hole-in-the-middle effect is a secondary factor. It’s where the listener is well off-axis and the processing removes centre-stage sounds from L&R and dumps them in the C speaker that it’s potentially of most benefit.

“because it’s causing sync issue with your multiroom system”

I look at this the other way round; the Sonos system is causing sync problems with the AV system in my neighbour's house! He can’t use the best music settings on the AV amp without the Sonos introducing horrible effects.

“practical to expect Sonos, or any other multiroom audio system to….”

As already mentioned, I use ROON for my home system and it does allow user programable delays that would solve this problem. But I don’t have the problem as my rooms are acoustically pretty much separate and I use Meridian surround controllers in each one. They presumably have very similar processing times.

“music in never produced in 3 channel audio”

The point about ‘stereo’ encoded audio is that both channels contain amplitude, frequency and phase information for each source on the sound stage. Therefore by throwing enough processing power at the problem, you can work out exactly where on the sound stage each source is located. So in theory you could have as many channels as you like driving individual speakers across the sound stage. Obviously there are practical limits; resolution, bit rate, digital noise and phase accuracy etc. And the quantity and hence cost of the electronics to drive so many speakers. Today’s present ‘practical’ solution is 3 channels; Left, Right and Center.

But because the signal also includes phase information a really decent ‘stereo’ system can also give the reproduced sound stage a sense of depth as well as simple left/right positioning. And an AV amp can use that to provide rear sounds as well; just listen to the X fighters on Star Wars flying over your head from behind you. And using the rear speakers to play music helps with  the depth of the sound stage. Listening to music while writing this, I have my office system set to ‘Music’. Makes you feel that you are there on stage with the band.

Is is an ‘accurate’ reproduction? I have no idea as I don’t know what effects the original artist/mixer was trying to create. But it sounds more convincing to me. Is it worth the extra kit and costs? I think so. But then I have listened to the same music played in the same room with the different decoding options provided by the Meridian surround controller. If you haven’t listened to such a system and are happy with what you have then fine.

The new Dolby Atmos coding apparently includes height information as well. But I haven’t heard that yet.

Just been reviewing the specs for the Sonos Surround Sound implementation. The Arc Sound bar has 11 amplifiers and speakers built in. And it works with an additional sub-woofer and rear left and right speakers. It decodes all modern sound formats. Therefore there is a lot of software signal processing going on and hence the sound will be delayed. I wonder how Sonos are dealing with acoustically close rooms when you “add more speakers around your home for multiroom listening”?

TV sources played in a grouped room are delayed, music sources are in sync. 

Sonos is the source, and your neighbor’s AV system can’t sync with it with the setting you want to use.  

Roon may be the exception, don’t know, but not exactly a hardware speakers/amp multiroom audio system.  It only takes streaming sources for one thing.  Whatever...doesn’t really change that I don’t think it’s practical for Sonos to build in the ability in manually controlled delays to accommodate 3rd party/amp receivers dsp.

My point is that if 3 channel audio is superiors for creating a sound stage for music sources, then I would expect there have been a movement to start selling recordings in 3 channel audio at some point, particularly when HTs with 3 front speakers has become very common.  That would eliminate the need for any DSP and allow for it to play “as the artist intended”, and quite possible sell more experience in rooms/situations where TVs are not involved.

Simulated atoms music, or music remastered (or whatever) to be atmos in haphazerd way sounds horrible to me.  Music proberly produced for atmos sounds really good.

Number of speakers doesn’t equal number of audio channels.  Sonos has separate woofers and tweeters for some of the channels.  Side firing speaker do more work to bounce off walls and handle surround speaker duty, when no separate surround speakers are present.    I’m not saying there isn’t any sound processing going on, but the Arc isn’t exactly creating a audio channel that doesn’t exist in the source.

But Sonos minimizes delay as much as possible to stay in sync with the video source.  As already mentioned, delay happens when grouping with other Sonos rooms to minimize dropout for any network issues and allowing each grouped speaker to have a bit of a buffer.

We are moving toward object oriented audio where an instrument can be assigned an apparent location in three dimensions.

With respect to latencies (delays) it’s 30ms for the surround Room and 75ms for Grouped Rooms. If you Group TV audio in a surround Room, it will be about 45ms ahead of the Group. At the cost of some lip sync you can add some delay in the surround Room in order to better align it with other members of the Group.

I am sure I can serve out the rest of my life with 2 channel stereo for music without hankering for more channels, but this has been interesting. Where does MQA fit into all this?

Nowhere, I hope. It seems many have now written it off. Were you just casting around for all the music technologies you can safely ignore?

Yes/no! Since I remembered it in the context of Meridian, I was wondering if that folds into this stuff in some manner.

Yes, but in my opinion, it makes a big difference whether the audio was produced for object orient audio, or just two channel audio that a dsp passes through an algorithm to have audio come from locations that were never really intended during production.