Beyond stereo?

[Ralph Glasgal]

On ‎6‎/‎20‎/‎2017 at 5:34 AM, semente said:

Regarding the dispersion pattern of instruments, you can see from the image above that the cello produces sound in a different direction depending on the frequency it is playing; the balance between direct and reflected sound (ambience) will change as the melody develops.

 

If you add room reflections to the mix you will be making the speakers more obvious and the source of the sound and the reproduction of the ambience less credible/realistic.

I am a little late getting into this new forum.

You need to distinguish between "They are Here" and "You are There" recording and reproduction.  Your cello axial dispersion problem is only a problem if you want the cello to be with you in your room.  "They at Here" is only suitable for mono recordings of a single instrument or 2.0 recordings of very small combos but that seems to be a preoccupation of audiophiles and what you hear at shows.

 

What all my posts concern themselves with is the "You Are There" type of reproduction which is practical for orchestras, organs, jazz bands, rock concerts, games, movies, and video.  A good mic array like the Ambiophone placed say 3rd row center, will pick up all the sound that the cello emits with all its frontal direct and proscenium reflections directional cues intact.  So when you listen at home that data is delivered without distortion to each ear so you hear a cello on that stage.  The home listening room reflections are static but otherwise are like nearby seats and heads in a real hall.  But if you use rear speakers their effect can just be part of the mix and are actually beneficial or a least better than using room correction.  See my tutorial on Envelophonics.

[Ralph Glasgal]

1 hour ago, AJ Soundfield said:

Hey, Ralph sent us on this goose chase! 

 

I was curious enough to dig a bunch too LOL. I'm always interested in finding things I don't, or may not quite understand. I was also puzzled by early his head tracking/HRTF response to my comment, but again, I think there is clarification now. I would still like to hear a good 22ch demo 

Not too many of those around these parts, or any audio show I've attended

I don't know how many of you are AES members or are coming to The AES convention this October.  But the Ambiophonics Institute is a technical tour destination this year so you can come and hear many full surround systems if you sign up and get on the bus.  If you know anyone in the New York City area tell them to come here anytime and report back to you on what they hear.

[Ralph Glasgal]

58 minutes ago, AJ Soundfield said:

Well, there are methods for producing a wider listening area with stereo loudspeakers 

Yes.  I call them all Loudspeaker Binaural methods.  Ambisonics, Wavefield Synthesis, VMAX, BACCH, SRS, Sonic Holography, Lexicon Panorama Mode, etc. are some.  Dolby Atmos, and Auro 3D are not.  Some of these use more than two speakers and the speakers may not be at 60 degrees.  The restricted stage width was a problem that Blumlein discussed in 1931.  

[AJ Soundfield]

12 minutes ago, Ralph Glasgal said:

I don't know how many of you are AES members or are coming to The AES convention this October.

I am a member, but unfortunately can't make NYC due to my "real" work schedule, Soundfield being purely a hobby-business. Perhaps at the next one down towards FL.

[AJ Soundfield]

8 minutes ago, Ralph Glasgal said:

Yes.  I call them all Loudspeaker Binaural methods.  Ambisonics, Wavefield Synthesis, VMAX, BACCH, SRS, Sonic Holography, Lexicon Panorama Mode, etc. are some. 

PSR also (see first post in thread). This link was an interesting comparison vs a 2nd order Ambisonics system, though hamstrung by use of only 5 speakers I assume

[esldude]

In the other MCH thread someone asked if they had an extra pair of speakers and amps what was a good path to get a MCH setup going.  Here was my reply to that:

 

Well somewhere you need a Dolby Digital surround decoder or DTS or better. 

 

If just for kicks and sticking your toe in the waters at this point, I would suggest hopping on the local Craigslist and finding a cheap AVR with digital input and pre-outputs.  One should be available now or soon for less than $100.  The newer the better, and better if it has HDMI.  Denon, Marantz, Onkyo, and Harman Kardon are usually good suspects among common brands. 

 

So use your current amps up front, and your extra amp in the rear.  Use the line level outputs of the AVR to feed the amps.  So the AVR becomes surround decoder and pre-amp.  Many (most?) will have among its options decoding for a 4 channel system. 

 

Now AVRs are unwieldy beasts with likely a dozen or more baffling formats supported.  All become almost their own little world to operate.  Eventually from the initial chaos you will settle on one or two or so methods of use, and all the other stuff will be ignored.  You want Dolby Digital surround as a minimum though.  DD is 5.1 channels of sound with each channel being compressed something like MP3.  It can share available bits across channels so it works a bit better than MP3. 

 

You could add a center channel maybe a conventional good box monitor speaker.   I suggest if the initial trial is encouraging at all you do get a center channel.  You could add a subwoofer or not. The center channel might be powered by the center channel amp in the AVR sufficiently to taste the waters of multi-channel. 

 

Obviously all this is a low buck approach since you have some of the more expensive bits just sitting there begging to be used.

 

The cleaner version.  Find an Audio Video pre-amp.  Use it as a multi-channel pre-amp.  Hook everything up and get a center channel.  Oddly, without amps and all the other stuff in a AVR, the AVP usually costs 3 times or more money.  The AVP is therefore not commonly seen on craigslist or at all. 

 

Another possibility, is getting a cheap recording USB audio interface with at least 6 or 8 channels.  Feed it digitally and use as a preamp.  I don't know right off hand of an easy convenient way to do the decoding for surround in the computer for most formats though it should be possible.  If you could do your surround decoding in the computer and feed the resulting MCH format out the audio interface you have it made pretty clean and simple.   Hopefully someone else will tell us the easy way to do that as I need to myself.

[esldude]

Ajax then responded:

 

9 hours ago, Ajax said:

I just purchased a second hand Emotiva UMC-200 Preamp/Processor. These units are about 4 years old but have all the digital inputs and formats you will ever need. They sound great and are around US$400 used. Just add your existing power amps and speakers plus sub and centre speaker. Not expensive and a lot of fun.

Yes this is the next best step up from an AVR.  A friend has one and they are very good.  I would add the UMC-200 has some useful parametric EQ functions and works more simply than many AVRs. 

[AJ Soundfield]

17 minutes ago, esldude said:

In the other MCH thread someone asked if they had an extra pair of speakers and amps what was a good path to get a MCH setup going.  Here was my reply to that:

 

Well somewhere you need a Dolby Digital surround decoder or DTS or better. 

 

If just for kicks and sticking your toe in the waters at this point, I would suggest hopping on the local Craigslist and finding a cheap AVR with digital input and pre-outputs. .

Hi Dennis, yes, I mentioned something similar and linked a "stereo surround" setup in this post https://www.computeraudiophile.com/forums/topic/32135-beyond-stereo/?page=2#comment-677367

For movies I use a modern AVR, but for 2ch music I use a similar setup like this

 

I found Dr Greisingers Logic7 to have the best performance for the rear channels. The fronts remain "pure" stereo

[AJ Soundfield]

15 hours ago, esldude said:

Well somewhere you need a Dolby Digital surround decoder or DTS or better. 

 

If just for kicks and sticking your toe in the waters at this point, I would suggest hopping on the local Craigslist and finding a cheap AVR with digital input and pre-outputs.  One should be available now or soon for less than $100.  The newer the better, and better if it has HDMI.  Denon, Marantz, Onkyo, and Harman Kardon are usually good suspects among common brands. 

One of the reasons I went with the above setup, is that I found I preferred "pure" stereo LR channels vs any of the upmix algorithms of DD, DTS or Logic7. I intend to conduct some experiments with the local audio club to see if I'm deluding myself. The issue of whether to use a center or not is also an interesting one, especially with LR speakers that utilize this research http://www.linkwitzlab.com/Links/Optimized-listening-area-Davies.pdf and this http://www.google.ch/patents/US20090060236

No question a real center reduce timbre distortion from stereo combing, but the question is how much is actually preferred with music

[AJ Soundfield]

On 6/20/2017 at 3:48 AM, semente said:

Despite my relative ignorance in audio matters I suspect that for accurate reproduction of an instrument or singer one would need to record its sound in anechoic conditions with a large amount of mics distributed equally around it in a sphere-like grid, then feed each channel into the equivalently positioned driver of a sphere-like speaker.

That would not represent what 2 ears + head would hear, especially in a typical performance space.

I have yet to attend a music event in an anechoic chamber 

[Ralf11]

this thread will get -really- interesting when VR comes out

[semente]

50 minutes ago, AJ Soundfield said:

That would not represent what 2 ears + head would hear, especially in a typical performance space.

I have yet to attend a music event in an anechoic chamber 

 

Perhaps you should reread  what I wrote.

If you wish to reproduce the radiation pattern of say a violin you'd have to do something similar to what I described.

You room would be the venue so you wouldn't be listening in an anechoic chamber.

 

This is a more accurate method of the rather simplistic AR live vs. reproduced demos. 

[AJ Soundfield]

36 minutes ago, semente said:

You room would be the venue so you wouldn't be listening in an anechoic chamber.

That would work great if you listen to live violins in your room and wanted to listen to a recording of it without it being there.

What would that have to do with how most folks hear violins?

[STC]

2 hours ago, semente said:

 

Perhaps you should reread  what I wrote.

If you wish to reproduce the radiation pattern of say a violin you'd have to do something similar to what I described.

You room would be the venue so you wouldn't be listening in an anechoic chamber.

 

This is a more accurate method of the rather simplistic AR live vs. reproduced demos. 

 

Are you telling that if you play a real violin in concert hall and your room, it is going to sound the same ? That cannot be correct. 

[AJ Soundfield]

4 hours ago, Ralf11 said:

this thread will get -really- interesting when VR comes out

Well, there are issues to be dealt with first.

This is an interesting video about spatial audio and a bit of history of 2ch through to now possibly several hundred channel...and the problems that start to arise, like spatial aliasing and "realness"

https://www.youtube.com/watch?v=y82nth2Pnwk

 

[semente]

9 hours ago, AJ Soundfield said:

That would work great if you listen to live violins in your room and wanted to listen to a recording of it without it being there.

What would that have to do with how most folks hear violins?

 

I guess you'll have to read my prior posts to find out.

 

But how is it that most folks listen to violins?

I guess they sit in a room and hear the sound coming out from the violin.

And conventional recordings and speakers cannot reproduce the sound of a violin accurately, the can only recreate a two dimensional illusion of what the violin sounded in the room it was playing in mixed with the reflections produced by your own room.

 

Please don't reply.

You win.

[semente]

7 hours ago, STC said:

 

Are you telling that if you play a real violin in concert hall and your room, it is going to sound the same ? That cannot be correct. 

 

That is not what I wrote.

 

Conventional recordings and speakers cannot reproduce the sound of a violin accurately, the can only recreate a two dimensional illusion of what the violin sounded in the room it was playing in mixed with the reflections produced by your own room.

 

What I mean is that you are looking for convincing holographic realism from a violin recording you won't get it unless you mic it all around and use an omni speaker AND you will have to give up on the original space.

[STC]

25 minutes ago, semente said:

 

That is not what I wrote.

 

Conventional recordings and speakers cannot reproduce the sound of a violin accurately, the can only recreate a two dimensional illusion of what the violin sounded in the room it was playing in mixed with the reflections produced by your own room.

 

What I mean is that you are looking for convincing holographic realism from a violin recording you won't get it unless you mic it all around and use an omni speaker AND you will have to give up on the original space.

 

We agree that conventional recording may not capture al the sound of the violin. But what should matter is the recording should capture the sound that reaches our ears. THe sound that reaches our ears is only a fraction of the original sound.

 

It is wrong to say that speakers only reproduce 2 dimensional sound. A vocal recorded in mono should sound quite close to the original sound when played with a single speaker. That is 3D. Any sound reaching our ears from any source be it speakers or instruments are all behave the same way.

 

So if a violin played in two different venue going to sound different than even the recording that you mentioned in posts earlier also going to sound different. The problem is we are trying to recreate many instruments that were placed at various spots in actual event be confined to two or five or seven or 11 speakers. The front stage where an orchestra of 100 instruments are stil being reproduced by two or three speakers (LCR).  

 

So the recreate the realism, maybe your method of recording and reproduction is better but  it still limited to 2 or 3 speakers in the front to reproduce the multiple instruments. The proper way is to place the many instruments captured in the recording with the two speakers.  

 

The next stGe after addressing the former is recreate the venue. The so called room acoustics can be minimised or even replaced with creating our own by replacing our room wall with the impulse response of actual concert halls which is commercial available. Unfortunately, this requires more speakers for the venues acoustics.

[AJ Soundfield]

3 hours ago, semente said:

But how is it that most folks listen to violins?

I guess they sit in a room and hear the sound coming out from the violin.

And conventional recordings and speakers cannot reproduce the sound of a violin accurately, the can only recreate a two dimensional illusion of what the violin sounded in the room it was playing in mixed with the reflections produced by your own room.

It's helpful if you are aware of the field of psycho-acoustics and what has been found about perception of reflections, playing same instrument in different rooms to same people, etc, etc.

Try watching the Rumsey video I just linked, much of this is covered, or anything Dr Toole has written. All helpful here.

[semente]

3 hours ago, STC said:

 

We agree that conventional recording may not capture al the sound of the violin. But what should matter is the recording should capture the sound that reaches our ears. THe sound that reaches our ears is only a fraction of the original sound.

 

It is wrong to say that speakers only reproduce 2 dimensional sound. A vocal recorded in mono should sound quite close to the original sound when played with a single speaker. That is 3D. Any sound reaching our ears from any source be it speakers or instruments are all behave the same way.

 

So if a violin played in two different venue going to sound different than even the recording that you mentioned in posts earlier also going to sound different. The problem is we are trying to recreate many instruments that were placed at various spots in actual event be confined to two or five or seven or 11 speakers. The front stage where an orchestra of 100 instruments are stil being reproduced by two or three speakers (LCR).  

 

So the recreate the realism, maybe your method of recording and reproduction is better but  it still limited to 2 or 3 speakers in the front to reproduce the multiple instruments. The proper way is to place the many instruments captured in the recording with the two speakers.  

 

The next stGe after addressing the former is recreate the venue. The so called room acoustics can be minimised or even replaced with creating our own by replacing our room wall with the impulse response of actual concert halls which is commercial available. Unfortunately, this requires more speakers for the venues acoustics.

 

1 hour ago, AJ Soundfield said:

It's helpful if you are aware of the field of psycho-acoustics and what has been found about perception of reflections, playing same instrument in different rooms to same people, etc, etc.

Try watching the Rumsey video I just linked, much of this is covered, or anything Dr Toole has written. All helpful here.

 

I am discussing this from the perspective of recreating in your listening room the radiation pattern or soundfield of an acoustic instrument.

Reproducing the recording of a violin playing in a music hall with 2 or even 5 channels will not do it.

 

My point is that a conventional recording will not be able to provide a realistic holographic soundfield of the violin.

 

But conventional recordings or photography or cinema can or may, with some degree of abstraction from the listener/viewer, provide a representation of the original musical event, sound, object, landscape, person...

 

And with this I return to my original comment where I mentioned that I find accurate sound reproduction more important than space reproduction in regards to music.

[AJ Soundfield]

5 minutes ago, semente said:

Reproducing the recording of a violin playing in a music hall with 2 or even 5 channels will not do it.

So how do you explain this? http://www.onhifi.com/features/20010615.htm

It seems clear you're either not reading any of the research linked, or not understanding

[STC]

7 minutes ago, semente said:

My point is that a conventional recording will not be able to provide a realistic holographic soundfield of the violin.

 

It can but not with stereo. But further discussion requires both of us to have experimented with all the different formats to know what's the difference. 

[semente]

44 minutes ago, STC said:

 

It can but not with stereo. But further discussion requires both of us to have experimented with all the different formats to know what's the difference. 

 

Listening is not helpful here.

I'll sketch a drawing latter today to better express my idea. 

[semente]

52 minutes ago, AJ Soundfield said:

So how do you explain this? http://www.onhifi.com/features/20010615.htm

It seems clear you're either not reading any of the research linked, or not understanding

See previous post.

There's no point in discussing further until I have made myself clear.

I am happy to stand for criticism then.  

[AJ Soundfield]

3 minutes ago, semente said:

 

Listening is not helpful here.

Well there you have it