[opaqueice]

So, once again it's possible to debate how important it is, but mathmatically it's not possible to debate that it's real.

Sorry, but I'm still not getting it.

I see how you can process a stereo signal and use two closely spaced speakers to make the soundstage very broad (for a listener in a narrow sweetspot).  You'd do it by adjusting the phase so there's a near-null at one ear, just as I mentioned above.  I don't understand your notation, but I guess that's what an identity matrix means.

What I don't see is what this has to do with accurate sound reproduction starting from a standard stereo recording.  As many have pointed out, a real sound field has lots of sources, comes from many directions, and both ears hear at least a bit of every source.  The only way I can imagine this ambiphonics approach could make sense would be if you started from a binaural recording - then you would know what each ear should hear, and you could try to filter the recording to compensate for the fact that it was being listened to over loudspeakers rather than headphones.

But very few recordings are binaural - and if the mics are not at approximately ear-distance apart, or if more than two mics are used and then mixed down, or if phase/polarity is adjusted differentially in the two channels during mixing, that information is gone forever, and no amount of processing can ever get it back.  Not only that, but each recording is made differently, so no single technique would work for everything.

[DaveC113]

The only absolutes I meant to say or imply where the ones about the fundamental laws of physics. I hope I didn't give the wrong impression about anything else.

That may be, but our understanding of science isn't always perfect. The diagram with the 4 arrival points and sound "rays" is misleading, and the conclusions drawn don't make sense to me. The other issue I see is discrediting the 2 channel stereo image with the "ray" diagram, while the imaging and xtalk cancellation in the ambiophonic system clearly uses the same principles of constructive and destructive wave combinations to achieve an image outside the narrowly placed main speakers. So you hear sounds coming from places where there are no speakers, just like a 2 channel system. I don't doubt there are advantages to the ambiophonic system over a 2 channel system, but I'm not sure it will be a clearly superior option to every listener. I would love to check it out sometime though.

For me, I just couldn't see the extra equipment not having a big negative impact on the sound quality without spending enormous amount of money, which if spent on the 2 channel system could make it even better... so I'm not sure its for me even if I like it, I can barely afford 2 audio channels.    

DGO, don't take it too seriously, its just an internet forum    (becasue I would like to hear about your experiments with it)

Dave

[sunshinedawg]

That may be, but our understanding of science isn't always perfect. The diagram with the 4 arrival points and sound "rays" is misleading, and the conclusions drawn don't make sense to me.

Don't think of it like that then. You might get incorrect conclusions by inputing too many variables and trying to calculate their outputs. Just think about it like this, is it possible to have one distinct sound in 2 different places at the same time in the real world?

So you hear sounds coming from places where there are no speakers, just like a 2 channel system.

Yes, that's true, but like Miklorsmith pointed out earlier in this thread, I'm putting the sounds where my brain is expecting them, similar to a live event, without adding artifacts.

[Daygloworange]

I hope you change your mind, you have already offered a lot to this thread. I am enjoying this thread, I have already learned stuff I didn't know.

In order to avoid butting heads, I'll respectfully decline anymore elaborations.

Just try a couple of the simple experiments I suggested earlier (so you can better understand my position on how stable a center image can be in a L/R speaker configuration).

And do check out binaural recordings. Listened to with head phones, they can be astonishing.

I used to know these guys that used to run around in the outdoors with DAT recorders and parabolic stereo shotgun mics, and make frighteningly real recordings of nature sounds, and thunderstorms.

Having said that, and seeing that perhaps you want to look at different perspectives of sound reproduction, I'll point you in a few directions you might find truly interesting.

Most of this stuff I became exposed to in books on studio engineering many years ago. I don't have the books anymore (either loaned out, or lost) so I can't give you direct paths to where to find some of these things.

Remember, Google is your friend.

As far as your question on 5 channel audio. Because of the experiements I did with Q4 type recordings, and what I later read about 3 channel audio (experimented with way back in the 1930's IIRC) after Les Paul (the father of the "Log" [first solid body electric guitar}, the subsequent Gibson Les Paul, and father of multi track recording) began recording with, I feel that if you were to add a center channel in order to avoid potential effects of interference to a L/R setup in the forward portion of a Q4 type system and add a mono center signal, you could achieve absolutely stellar, phase (stable) and correct holographic audio reproduction.

The front 3 channels could be recorded in a number of different multi mic configurations, to subjectively or objectively (depending on personal preferences) set the front soundstage in a holographic manner, and the rear channels would be done in a simple X/Y arrangement to add stereo rear ambiance.

I must also admit, that after hearing the Ray Kimber "IsoMike" demonstration at RMAF 2007, I was not left with a very optimistic of the surround type systems that people are developing at the moment.

I'm not entirely ready to write off any of these techniques either. I'll have to do some more investigating as well, because the idea of full surround playback still very much interests me, as I have the ability to record my own multi-channel recordings, and play them back.

Cheers

[bpape]

Don't think of it like that then. You might get incorrect conclusions by inputing too many variables and trying to calculate their outputs. Just think about it like this, is it possible to have one distinct sound in 2 different places at the same time in the real world?

Actually, yes it is.  A sound eminates say from a dome tweeter.  That sound comes at you but also goes off at an angle, bounces off a wall, and then gets to you at a different time.  To extrapolate then, the same sound is at a different place (not to you yet) at the same time that the direct one is reaching you.

Carry on...

[sunshinedawg]

Actually, yes it is.  A sound eminates say from a dome tweeter.  That sound comes at you but also goes off at an angle, bounces off a wall, and then gets to you at a different time.  To extrapolate then, the same sound is at a different place (not to you yet) at the same time that the direct one is reaching you.

Carry on...

Ok, I should have said a sound coming directly from the source to your ears.

Man, you guys are good, you don't miss a trick. That's why I'm loving this thread, the feedback is great! 

[Daygloworange]

Not to be a sh*t, but there's also the ceiling, the floor...

Cheers

[sunshinedawg]

I must also admit, that after hearing the Ray Kimber "IsoMike" demonstration at RMAF 2007, I was not left with a very optimistic of the surround type systems that people are developing at the moment.

Yeah, I agree there. I've gone the last few years to the 'IsoMike' and didn't really get it. I think last time he actually recorded that quartet, so you could compare the live version and isomike while it was fresh in your mind. The live version was great with them playing in the hallway, the playback didn't do anything for me

[bpape]

If all sound acted as a ray, then the answer would be no and the forumulas you're using would be valid.  That would also assume that you're in an infinitely large space, or outside, and suspended in mid air.  But you're not, they don't, and it doesn't work that way - sorry.

You HAVE TO take into account the room, the non-direct sound, the change in time, the change in frequency response off axis and time, etc.  To throw another wrench in the works, the non-raylike (word?) nature of the sound changes as frequency changes.  Highs do act somewhat like a ray. Bass is a 360 degree, 3 dimensional spherical pattern.  How do you model that in a 2x2 matrix?

Then you also have to throw the 3rd dimension into it, and the 4th.  A simple 2x2 matrix simply isn't sufficient to even come close to modelling a real world soundfield in a real world room.  

Bryan

[Daygloworange]

I must also admit, that after hearing the Ray Kimber "IsoMike" demonstration at RMAF 2007, I was not left with a very optimistic of the surround type systems that people are developing at the moment.

Yeah, I agree there. I've gone the last few years to the 'IsoMike' and didn't really get it. I think last time he actually recorded that quartet, so you could compare the live version and isomike while it was fresh in your mind. The live version was great with them playing in the hallway, the playback didn't do anything for me

You mean this quartet?



Yeah, I was there for quite a while after hearing the IsoMike thing earlier in the day.

I snapped the pic because I wanted to start a thread in "The Acoustics Circle". I have heard dozens of string quartets (live)during my years studying classical, and this quartet sounded like crap in the lobby of the hotel at RMAF.

The acoustics of the lobby (that you can make out in the pic) absolutely destroyed the richness and suprisingly, the dynamics of the quartet.

I have enjoyed MUCH better sound coming out of my 2 channel system, than this(and other) LIVE events.

Cheers

[sunshinedawg]

You mean this quartet?

Actually when I heard them, they were in the hallway down by the elevators to the towers. Sounded great to me. I was standing about 5 feet from them.

[Daygloworange]

You mean this quartet?

Actually when I heard them, they were in the hallway down by the elevators to the towers. Sounded great to me. I was standing about 5 feet from them.

I wish I would have heard that performance, but alas, I didn't.

It would have been very interesting to hear the same quartet play by the elevators. IIRC the ceiling there was very high, and the space was quite wide and large, with the same tiles on the floor as the main lobby.

I'm sure it would have sounded like a whole different thing.

I'm sorry I missed that.

I was probably debating how the MBL room sounded at RMAF with another AudioCircle member or something.....

Cheers

[*Scotty*]

While the results may be inconsistent,recordings that have been processed with a HRTF algorithm and played back through my stereo system are quite satisfying to me. The only thing I haven't heard has been the placement of the acoustics of the recording venue that a listener would have heard had they been in the same position in the hall
as the microphones. I don't know what is possible with this sort of processing. I suspect that it's effectiveness is in part dependent on how well a loudspeaker disappears or is equivalent to region of space with sound emanating from it. Extensive treatment of the listening room to reduce the magnitude of first reflections would probably also be helpful.  I have heard well focused images of instruments placed 360 degrees around my listening position. This effect, when present is a head in the vice kind of thing, you can shift from side to side a few inches but you can't turn to look at the virtual image to the side or behind you. The Thievery Corporation:TheCosmicGame is a very good example of this kind processing. Non digital Dolby Encoding of movie soundtracks is also pretty interesting.  Movies that are Dolby encoded have most of the same effects at my home that are heard from the film when it I saw it in a movie theater. Maybe all of the extra channels and expense are not entirely necessary for an immersive listening experience.
Scotty

[lonewolfny42]

You mean this quartet?

Actually when I heard them, they were in the hallway down by the elevators to the towers. Sounded great to me. I was standing about 5 feet from them.

That was more of an open area....had the stairs behind them leading to the balcony floor.

[sunshinedawg]

Don't think of it like that then. You might get incorrect conclusions by inputing too many variables and trying to calculate their outputs. Just think about it like this, is it possible to have one distinct sound in 2 different places at the same time in the real world?

Actually, yes it is.  A sound eminates say from a dome tweeter.  That sound comes at you but also goes off at an angle, bounces off a wall, and then gets to you at a different time.  To extrapolate then, the same sound is at a different place (not to you yet) at the same time that the direct one is reaching you.

Carry on...

I said at the same time not a different time. I was implying that it would arrive at the same time at your ears directly from the source without reflections or any other interference. Maybe said better, it is possible for a distinct sound, ie somebody's voice, to be produced in two different places at the same time in the real world?

[dorokusai]

As clearly seen in the illustrations in the link provided by JeffB, there is one little hitch in the theory as far as I can see, and that may be explained by the fact that in the hypothetical paths shown from the drivers to the ears of the listener, only one path is shown from the "dimension array" to the listeners' ears, not two as would actually be the case.

In other words a 2nd correction signal could be arguably required to correct for the 1st correction signal for the very same reason a correction signal was employed in the first place.

The absence of that signal (and, of course, it would be impractical) could account for the occasional sound being "thrown" out of the soundstage as you describe, Mark.

And in response to this from WindChaser:

"Common rules and schools of thought only pertain to common design and do not apply to OB."

I think the toe in technique does (and should) work with OB as well as with omnipolar speakers.

I imagine Clayton Shaw has tried a few demonstration configurations and seems to have settled on just this arrangement, probably because it works for the usual reasons and in the usual way - by broadening the sweet spot.

I have read a few comments on the demos to the effect that one notable characteristic of the set up was that the stereo image was stable as one moved around the room.

Russell - Thanks, and that certainly makes sense to me.

I thought by looking at "Recent Posts" I would see the threads I responded to but apparently not....sorry for the late reply.

Mark

[doug s.]

i am still waiting for someone to address the points i made in my last post to this thread:

i have found this conwersation quite interesting.  sitting on the fence as a casual obserwer, as it were.  i used to own a jvc xpa1010 dsp, which allowed the set-up of four ambient speakers to mimic 20 different venues from real locations which were programmed into the dsp - churches, concert halls, clubs, etc.  with some software, the effect was eerily realistic.  that said, i rarely used it.  why?  because, in most instances it was not really better than my normal 2-channel playback system, yust different.  in spite of some statements in this thread that were made as facts, about what is not physically capable of being done with 2-channel audio, i easily experience a soundstage that's detached from the speakers, wider than the speakers, higher than the speakers, with real depth of the soundstage, etc.  this is no anomaly; it's present in many recordings, and on a lot of the fm i listen to.  so, while it may be impossible, i experience it on a regular basis.   

also, while i understand that when a pair of stereo speakers is playing, there are four distinct arrivals - both your ears hear each speaker.  but, i also know that when i listen to a live duet on a stage, there are also these same four distinct arrivals.  yust cuz the duet is live, doesn't mean my left ear isn't hearing the right player & wice-wersa.  perhaps this helps to explain why conwentional two-channel audio playback can do such a credible yob of reproducing a believable soundstage with decent recordings...  even when hearing a believable soundstage from two-channel audio is flatly impossible, according to some of what i have read here...   

ymmv,

doug s.

doug s.

[Daygloworange]

Doug,

You know I'm with you on this. In a large room setting, with room treatments, I get huge soundstaging, well outside the boundries of the speakers and absolutely holographic center imaging, with incredibly coherency.

No hype.

It sounds like 3 channels. L/R and center.



Cheers

[Mag]

I don't understand what you are saying, but I'll offer my .02 cents.

IMO stereo with just 2 speakers fails because, it's a narrow direct beam, that reflects off the walls creating an image. It may sound good, but it doesn't fool my brain into thinking it's anything other than a stereo.
When you're sitting in front of a band at a bar or concert. The stage is very wide, and although we are able to discern the sound coming from the front. The majority of the direct sound is hitting our ears from the side.
Having multiple speakers using stereo. I find that sound coming from the side speakers dominates sound coming from the front speakers, ever so slightly. However I still perceive the sound coming from the front. The front speakers actually act as filler, in the soundfield gap, without them though the illusion of 180 soundfield is gone.
Using multiple speakers in stereo widens the narrow image presented with just 2 speakers. The trick is to get them to blend together as if they're one speaker. This is done by having matched speakers and by placing them in the sound holes. When placed appropriately, with proper tweaking such as toe in, you will have a seemless convincing 180 degree stereo image.

[Daygloworange]

Mag,

Not sure If you were addressing my last post, but I'm talking about live acoustic events, not amplified events. I've never heard any amplified event every being worthy of me wanting to reproduce it in my 2 channel system as I heard it at the venue. PA systems are hardly Hi-Fi. The microphones used in a live situation are designed for high gain before feedback, high SPL handling, durability, and often have frequency responses that are tailored (deviate from flat FR). Add all these elements together, and you couldn't be farther from Hi-Fi.

I have a numerous classical recordings that through my 2 channel system, sound as good, if not better than being at a live classical concert.

There are others who possess systems capable of at least what I am experiencing, and quite a bit beyond as well. I'm not done elevating my systems performance.

Cheers