Blue or red pill?

[gmgraves]

12 hours ago, mansr said:

Another note on stereo recording. In my earlier post, I discussed an XY microphone setup. Consider instead using spaced omnis. Here the difference in distance between the sound source and each of the microphones produces a variation in output level. Additionally, there will be a phase difference with the more distant microphone delayed relative to the nearer one, and this may contribute to our interpretation of the sounds on playback. This still does not, however, help with height or depth localisation. Any points with the same difference in distance to the microphones will give identical outputs aside from overall amplitude. Although the shape of the surfaces formed by such points will be different than for the XY configuration, the effective result is still a total loss of height and depth information. The same is true for any recording method using two microphones.

I think this is a terrible idea, but a lot of recording and broadcast engineers agree with you. Spaced omnis give a lousy stereo image because they aren't phase coherent. That means, among other things, that you can't mix a recording made with two spaced omnis into mono. Phase cancellations wreck havoc on the resulting mix. Bob Fine of Mercury Living Presence fame found that out early-on. He was making stereo recordings for Mercury before there was a stereo disc to distribute those recordings on. The commercial releases of these early stereo recordings had to be monaural. He quickly found that mixing the the two stereo tracks down to one didn't work. He needed to add a third channel and have his Ampex 300/350 tape recorders modified to three tracks instead of two and he added a third omni microphone in the center. It was from this third center mike track that the mono versions of his Living Presence recordings were cut. When stereo records were finally rolled out in late 1957, he found that the center of the two channel stereo tracks were so confused, image and phase wise, that he started to mix the center channel (originally there only to provide a mono feed)  equally into the left and the right channels. 

[gmgraves]

3 hours ago, esldude said:

I don't disagree with what you have posted on this. 

 

However, some X-Y recordings have the microphones positioned to line up the center of the diaphragms and have one positioned a fraction of an inch above the other.  This means that while the directional characteristics are symmetrical there is a distance difference when sounds originate from an upward or downward direction.  When you have differences of distance you'll get comb filtering.  Such could be in the right frequency range to create a sense of height.  It wouldn't be accurate (except by accident), but it seems to me you'll get a notch in the FR in the right area to trigger height perception.  

 

Easy enough to experiment with and see if it happens.  If I weren't occupied with important matters currently I would do it.  May get around to it later if no one else does.  George Graves 

@gmgravesuses a microphone that has the diaphragms aligned vertically in one package, and he reports his recordings display height.  Maybe he could provide a snippet of one that can demonstrate. 

 

You can see below how X-Y and ORTF can have a difference in positioning that is offset vertically.  

 

 

 

 

Frankly, that amount of vertical displacement is not enough for the microphones to even notice. But what you show above is not an X-Y, pair it's an A-B pair. A true X-Y configuration does not have that vertical displacement. I don't use A-B or Blumlein coincident with separate mikes because there are enough things to worry about when setting-up to do a location stereo recording than worrying about reversed channels (in the above examples, the left-hand mike is point at the right side of the ensemble and vice-versa!). Below, Image #1 is True X-Y and image #2 is Blumlein Coincident.

[gmgraves]

3 hours ago, sandyk said:

 

 That could be quite interesting to listen to..

 Let me think about it. I suppose I could send a few interested parties a snippet from one of my symphony recordings via "We Transfer". If I decide to do it, those interested will have to e-mail me and then I'll make arrangements to do a one time mass transfer to all interested parties. BTW, the stacked arrangement of the Avantone CK-40 stereo microphone has nothing to do with the height aspect of the recordings, that;s due to the fact that the mikes are used in cardioid pattern and true X-Y mode. One can have equally good stereo results with a pair of cardioids mounted on a T-bar at any anything from 5" apart to 18" apart (French ORTF). If I make a snippet or so available it will be a symphonic recording made with a pair of Sony C-37P mikes on a stereo T-bar. The mikes are shown below. 

[gmgraves]

12 hours ago, mansr said:

I'm not following. If one microphone is placed above the other, sounds from above or below will have a slight phase shift. There is still only a single wave, so there can be no cancellation, and both microphones receive the same strength at all frequencies. This is assuming the sound source is well in front of the microphone pair. If the sound were coming from straight above, the upper microphone would obviously cause some interference or other for the lower one. For any reasonable recording setup, this should not be an issue.

If one microphone is significantly higher than the other, then you are right. There will be some phase shift. But if the two stacked microphones are almost touching one another, the microphones' vertical pickup patterns are not precise enough for there to be any noticeable or even measurable difference. It's a lot like using two omni-directional microphones in an X-Y, A-B, or Blumlein coincident configuration. The result will be dead mono. There will be absolutely no difference between what the left microphone "hears" and what the right microphone hears. Yet, do the same experiment with two cardioids and you get glorious and real stereo! Now you can use two omnis in the above stereo configurations (all except Blumlein Coincident) if there is a gobo or baffle between the two omni mikes, but even that configuration will only give stereo above the frequency where the size, shape and absorptive characteristics of the gobo determine the frequency at which the wavelength of the sound is above the cut-off frequency of the baffle itself. Ray Kimber's "IsoMike" main baffle is huge, certainly larger than 6 ft in diameter and is shaped like a valentine heart. He gets stereo out of a pair of closely spaced omnidirectional calibration mikes that covers the entire frequency range, but then his recording setup is too huge to be practical. Luckily he had a college auditorium to himself to set up his system.

[gmgraves]

1 hour ago, Don Hills said:

While the discussion of perceiving height cues is interesting, I fail to see the relevance. I've never been to a performance where the players are stacked vertically.

In most concert halls, when the percussionist hits the triangle, it seems to float above the left side of the orchestra. Yes, it's an auditory illusion, but a true stereo mike setup will capture that effect and replay it in ones listening room where it seems to float above the left speaker. Also, usually in most large ensembles, the brass instruments in are in the last row back and usually on risers. That means that they "speak" from higher-up than do the woodwinds in front of them and the violas and cellos in front of the woodwinds. Couple that ability with the front-to-back layering that real stereo imparts and you get the ability to pinpoint each instrument in three dimensional space right-to-left, front-to-back, and height off the floor. When done right the imaging can be jaw-dropingly  uncanny!

[gmgraves]

12 hours ago, mansr said:

You must be using different definitions than everybody else. Any coincident configuration, be it XY, Blumlein, or MS, is impossible to realise perfectly since two microphones can't be in the same place. The best we can achieve is an approximation involving some displacement from the ideal position. A vertical separation has the advantage that it behaves correctly for sounds originating in the plane of the microphones. In your lower image, the microphones have instead been moved sideways (or backward along their axes if you prefer). This means any off-centre sound will have a slight phase difference between the microphones, though it is probably small enough not to be a problem. Your first image shows an ORTF configuration. The only other page I can find (using Google image search) featuring it even says so explicitly.

Let me ask you this: Are your two ears in the same place? And you're right about that phase shift. Not only is it small enough not to be a problem, it's small enough to essentially not exist in such a way that it can be either heard or even measured by any conventional means. Now, above 20 KHz where the wavelengths are in inches or shorter, that might present a problem, but it isn't a practical problem over the audible spectrum. 

[gmgraves]

43 minutes ago, Kal Rubinson said:

But the ceiling (or lack of one) is responsible for a portion of the ambiant sound field.

 

That is also a consideration.

[gmgraves]

19 hours ago, mansr said:

I'm not disagreeing. What I objected to was the idea that there would be somehow be a cancellation of some frequencies.

There might be some cancellation of ultra-sonic frequencies, but it's irrelevant. 

[gmgraves]

3 hours ago, mansr said:

A stereo recording unambiguously captures the direction of a sound source. Depth is not captured whatsoever. When we perceive a reproduced sound as distance, it is because this fits our mental model of the world, not in any way because the recording actually contains depth information. Why do you persistently refuse either understand or accept this distinction?

My experience as well as that of Alan Blumlein in the 1930's; as well as people like John Eargle, Bert Whyte, and J. Gordon Holt more recently, tell a different story. Whether illusory or not. The phase cues that locate instruments nearer or farther away from a stereo pair and at (near) stage level or higher are generated by an ensemble playing live in an actual space. When we use true stereo miking techniques to mike the space that these instruments inhabit while playing rather than the instruments themselves, all the cues that humans use to locate sounds: right and left direction, whether the sources are nearer or farther away, whether they emanate from eye level or above eye level or below eye level, and whether they are coming from behind us are all in the sound field being generated by that musical ensemble and are reinforced by the acoustics of that space. If we place a stereo pair of microphones in that sound field, depending on how the microphones are made, what their characteristics are, and where in the sound field that they are placed, they are going to capture whatever part of that sound field that they are capable of capturing. A stereo pair of cardioids, for instance, aimed at an ensemble on the stage of an auditorium, will not pick-up much hall ambience from behind them because the mikes are designed to not have much sensitivity to sounds coming from directions that are severely off-axis to the mike's polar pattern. But, from the direction at which they are aimed, these mikes will pick-up all the directional, loudness and phase cues being generated by the musical ensemble being captured. These are the same cues that tell us human listeners that a sound is coming from the left or the right of us, whether that sound is nearer or farther away, and whether, like the squeak of a mouse, it comes from somewhere on the floor beneath us, or like the caw of a hawk flying in the sky above us, it makes us look up at the source of that caw! That sound field can be captured simply by using the right microphones in the correct stereo manner. 

[gmgraves]

4 hours ago, mansr said:

Are you seriously trying to claim that a pair of microphones can record the HRTF of a person who isn't even in the room?

 What the heck on you on about? Where in the world did you get the THAT ridiculous idea? 

[gmgraves]

3 hours ago, semente said:

 

What do you think would happen if the mics in the following video were pointing forward instead of downwards at the piano?

Would it sound like the piano was 10 feet below the speakers?

 

 

Let me ask you this: If you were floating 10 feet above the piano would the piano sound like it was 10 feet below you?  

[gmgraves]

3 hours ago, fas42 said:

The position I come from is simply an extrapolation of this: whether the intention was to capture this information or not, and whether the cues are partially or completely manufactured on the mixing desk makes no difference - a sense of space and depth can be experienced in all recordings, unless they went to extreme lengths to explicitly prevent this! The better the playback, the more "powerful", convincing is the sense of this - the perceived space may not be a single one; it can be multiple spaces, of different sizes, overlaid upon each other - as would intuitively be the case, the more the mix is manipulated the more the spaces seem separate, distinct from each other - but still with full integrity; each retains its indivduality.

 In my not inconsiderable experience, this is wrong. Mixing consoles have no facility for vertical placement of instruments nor do they have any way of moving an instrument forward or back ion the soundstage Individually miked instruments can be assigned to one channel on a mixing board and then can be "pan-potted" anywhere from all the way into the left speaker with nothing coming out of the right speaker to all the way into the right speaker with nothing coming out of the left speaker, or anywhere in between and that's it! It literally has nothing whatsoever to do with playback side. If the imaging cues aren't in the recording you are playing, the finest playback equipment in the world will not put them there. It's that simple. 

 

3 hours ago, fas42 said:

The advantage of aiming for the highest level of SQ is that all the recordings that one has can "unfold" in this manner - increasing the pleasure and satisfaction in the listening.

 

I'm sorry. There may be "something" there but it isn't an accurate representation of the actual sound stage. Accurate imaging is in the hands of the recordist, not in the hands of the hi-fi enthusiast doing the listening. If the recordists are using true stereo microphone techniques, the resultant recording will exhibit pin-point imaging in all three dimensions. It cannot be done with multiple microphones in a mixing console or with spaced microphones. 

 

Remember: "Stereophonic" is from the Greek word "stereos" which means solid and solid is three dimensional; that is to say that it has width, height, and depth. Stereo microphone techniques give you width, height, and depth. Spaced omnis give you width only, and individually miked instruments give you multi-channel monaural sound.  Only A-B, X-Y, Coincident miking, Middle-side miking, and ORTF (or some variant of it such as the Decca tree) can give real stereophonic sound. Everything else is just a collection of monaurally captured instruments mixed down into two channels and called stereo. Yes, there is a place for that kind of recording, Jazz has traditionally been recorded with each instrument individually miked and then in the final mix, the instruments are grouped into three groups: Left, right, and the "featured player" or vocalist is equally mixed into the right and left channel and appears halfway between the two speakers or in what is referred to as the "phantom third channel". This was started, IIRC, with recording engineer Rudy Van Gelder in the early days of stereo, and continues to this day. They do something similar with rock bands. Multi-channel playback, it might be, but stereophonic sound it isn't!

[gmgraves]

17 hours ago, fas42 said:

I'm not worrying about vertical positioning - and they can move sounds back and forth, by the application of reverb. The latter can create deeply cavernous spaces, with ease - yes, totally 'fake', but one's hearing can pick up the meaning, with no problems ...

 No, you can move an ENTIRE ensemble nearer or further by the ratio of direct sound to reverb, but you can't move individual instruments in an ensemble using reverb. 

 

17 hours ago, fas42 said:

It does depend on the playback, because if this is not of sufficient quality the cues are too confusing, too subtle; it just sounds like a mess. One reason pop recordings can be unpleasant to listen to is because the depth information is too tangled - presented at a high enough quality level, the mind can untangle what's going on, and everything makes sense. This is so reliable that I use complex pop recordings to assess unknown rigs - if what I hear is a mess, it means that the playback is doing too much damage to the cues, and it's a fail - for that system.

Simply poppycock. if the imaging cues are in the stereo recording, the cheapest, simplest stereo system will replay them in all their dimensions! My desktop system images beautifully and it consists of a $400 hybrid tube/SS amplifier and a $200 dollar pair of bass reflex "mini-monitors"!

 

17 hours ago, fas42 said:

Consider a jazz trio: the three are complete separated, use headphones to synchronise their playing with each other; the left player is set up in a huge hall, and recorded; the centre one is in a normal sized room, and mic'ed the same way; and then the right player is in a tiny recording booth, and similarly captured. The three tracks are mixed, with the lateral positions adjusted to give that left, centre and right, but no other 'fixing'.

 

In the playback, what will a listener hear?

 

Three channel mono.  A group of instruments in the left channel, a group of instruments in the right channel, and a group of instruments and/or the vocalist in the phantom center channel! In you're rather extreme example, the center and right channels will have artificial reverb added to match that of the musician(s) in the left channel. But this is totally irrelevant to my missive. I'm not talking about ambience our reverb, I'm talking about "on-stage" imaging.

[gmgraves]

14 hours ago, adamdea said:

I think this exchange is becoming futile because you are refusing to approach this from the starting point of how you actually localise sounds in the real world. Ignoring non auditory information (which is significant) this involves your brain analysing the differences in patterns of sound between the ears. Aside from general inter-aural time and ampitude differences there are spectral differences caused by the shape of your neck head and pinna. 

Those differences are crucial to much of our ability to localise sound. They are not encoded in an ordinary stereo recording. When the sound comes from two speakers not from an actual single point the path to your ears is different. Ergo the spectral cues even from sounds on the median axis are not regenerated. This is not debatable. 

Any person starting with a very basic knowledge of perception knows thus. 

 

So without a dummy head the spectral cues are not all recorded. Sensible discussion can only start by considering the importance of what is and is not recorded 

Well, having made literally hundreds of recordings of symphony orchestras, and many more recordings of smaller ensembles, I can tell you with some authority that you are wrong. In a real stereo recording, those cues are recorded and any stereo playback system can "reconstruct" them in your listening room. There are caveats here, though. Room acoustics can mess up those imaging cues (although the room would have to be pretty bad to do that) and, of course, small, more "point source" speakers tend to image more precisely than do many large speakers, but even big speakers can image well too - it depends on how they were designed. 

[gmgraves]

11 hours ago, mansr said:

You claimed that two regular microphones capture all the positioning cues a person would hear. Since these include HRTF effects, it follows that the microphones somehow, magically account for this. Binaural heads are an attempt to do exactly this, and it works to an extent. However, you insist that even a pair of plain cardioids will do it. That is preposterous.

 

Yes it is preposterous! That's one reason why I never mentioned Head Related Transfer Function. Microphones don't capture that (and aren't "trying" to capture it and don't need to capture it) and binaural heads aren't successful at capturing it (that's why binaural is so poor at localizing sounds behind the listener). Microphones, if used correctly, pick up the cues from the differences in sound intensity and phase that are created by the musical ensemble. These differences in perspective are capture by the recording medium and played back over speakers. The HRTF effects occur at the listener's head, in his own listening environment not at the recording microphone. I'd have thought that you would have realized that.

[gmgraves]

3 hours ago, semente said:

 

If we use dynamic compression and reduce gain wouldn't it be possible to "move" an instrument back in a recording?

Offhand, I don't see how. Perhaps if you were to explain your theory a bit more completely, I could see where you're coming from. 

[gmgraves]

1 hour ago, fas42 said:

 

Recordings sound enormously different from each other - 'quality' recordings are boring, generally - for the same reason that a super smooth, straight highway is far less interesting that a winding country road, for an enthusiastic driver - they are both means for people to progress quickly between two points, but I know which I prefer ...

 

Which means the cues that provide depth information are not "standard" in their quality, and level. They are always there, but vary in their audibility - between every recording. The higher the "resolving power" of the playback rig, the more likely a particular recording will show obvious depth - ultimately, it becomes impossible to find a recording that doesn't present a 3D picture in some manner.

That's where you and I part company. In my experience, a recording either has decent imaging or it doesn't. Realistic imaging is what I do, what I got into recording for. Most orchestral recordings don't image at all because they use a forrest of microphones all mixed together electronically. Most Jazz recordings don't image at all because they are recorded using the traditional three-channel-mono arrangement. Some people don't care about such things, but it is MY THING! If the imaging is not on the recording, (and I've said this before) then the finest stereo system in the world can't make the recording image, I can pick-out a studio recording a mile away. To me the two-dimensional aspects of it stick-out like a sore thumb.  

[gmgraves]

23 hours ago, fas42 said:

You can't ?? ... if the instruments are recorded separately, as in my post of the jazz trio - and different levels, settings of reverb are added to the individual tracks, then the result is a layering of the depth positions - I hear this behaviour in nearly all pop recordings; it's clearly defined to my ears.
 

No. You can't. And even if you could, who would want to do do so? To what end?

 

23 hours ago, fas42 said:

If the cues are extemely obvious then, yes, the lowest order playback will make the presentation very clear. But if the cues are more subtle, then only better playback will reveal that detail - the cues in the recordings are not on/off switches for our hearing, either present or completely absent - again, everything in audio is a continuum; there are always shades of grey.

 

If the recording is real stereo then the cues are extremely obvious. If the recording is some mishmash of multi-miking techniques, then, who cares? I don't record that way, so I certainly don't care. 

 

23 hours ago, fas42 said:

No, on a good system you will hear the performers overlaid upon each other, in the correct lateral position - with each 'operating' in the space as recorded - there will be a combined sound, and also the sound of each instrument echoing in the space as set up. In the hearing, you will be listening to the mix, and then soloing a particular player - exactly as if you had the controls of the desk under your hands.

 

I have a good system and I hear only overproduced, artificial sound, and I don't like it.

23 hours ago, fas42 said:

The imaging is a function of everything you can hear; the amount of "on-stage" presentation will be a function of where and how it was recorded.

I will agree that on-stage imaging only exists to the extent that the engineers and producers making the recording want it to exist. In pop recording, that's not at all, in most classical recording, it's not a big deal. There are purist recorders to whom it matters, and occasionally, just occasionally, one gets a recording that has been carefully crafted to give you-are-there imaging, but not often. It makes me wonder why the world went to the trouble to develop stereophonic sound in the first place. Very few people ever record it or listen to it, and fewer still, appreciate it. The vast majority of recordings that come out every year, are two or three channel mono. What was wrong with real mono? Neither one gets the listener any closer to the performance than the other.  Were I in a cynical mood, I might say that stereo was invented merely to sell the average audiophile two of everything, and while that might be part of the story, a lot of dedicated music lovers and engineers at both Bell Labs and the BBC in England, in the 1930s, believed that stereophonic sound could bring something of the concert hall to the listener's living room and that doesn't seem cynical to me at all. 

 

Look I'm tired of arguing this minutia back and forth and trying to explain to people who have never recorded in their lives what is and what is not possible to do with stereo. I don't even understand why people are arguing with me. Everything I have said is well known to anyone who has ever made a real stereo recording using tried-and-true stereophonic miking techniques and those who don't know about it can read-up on it. Studio pop recordings are different. I don't do those (but I have worked in studios that made them) and I don't care about the artificial processes and the work-arounds that studios use to avoid making honest, real, stereo recordings. 

[gmgraves]

20 hours ago, esldude said:

@gmgraves

 

Unless I missed it, did you make any samples available for download.  Easiest thing in the world is supply us with recordings with these cues and let us hear them.  If you are at liberty to share those with us. 

 No, I haven't. The reason is that I really don't see the point. Many of the people discussing this topic at this time on this thread, are only here to argue. If I We Transferred a recording to a list here, there would be two groups: One small subset of those to whom I sent the music will say that they hear what I'm talking about, and will be impressed with it, and the other subset will come back and say that I'm full of shit, and that the recordings don't image like I say they do and that they don't sound very good - even though they actually do image like I assert and they do sound very good. So, in the end, what do I get out of it? More pointless argument from people trying to press their untenable assertion that studio multi-miked, multi-tracked recordings can image just as well as real stereo? No thank you. 

 

[gmgraves]

23 hours ago, mansr said:

Correct, and that is exactly why a recording can't convey the necessary height cues. On playback, the HRTF responds to the location of the speakers, not the location of the instruments during recording.

Have it your own way. I'm sure you're more of an expert at this than I am. 

[gmgraves]

1 minute ago, Audiophile Neuroscience said:

 

I for one am not arguing against anything you have said. I have heard one of your recordings and confirm I heard depth and height information. Would you be able to briefly explain how this is possible without HRTF cues (as proposed by others).

I think I did that already. HRTF doesn't come into play at the CAPTURE of the sound. How could it? there is no head, no ears there! The microphones pick-up various phase, timing, and intensity cues that when played back on speakers involve the listener's head The speakers reproduce (in as far as they can do so) the sound field captured by the microphones and the head and ears of the listener pick-up that sound field just like they would were they in the venue listening to the performance live. Seems pretty straightforward to me.

[gmgraves]

3 minutes ago, mansr said:

Well, you managed to mislabel several standard microphone setups, so I'm really starting to doubt your competence.

Be my guest!

[gmgraves]

11 minutes ago, mansr said:

I'm arguing because you are making absurd claims.

Well, you are entitled to your opinions. No matter how wrong or misguided you are

[gmgraves]

3 minutes ago, sandyk said:

 George

 That's a shame.

 Alex

I hope you understand my position, Alex. If you want a sample, I'll happily send it to you. E-mail me with your E-mail address and I'll send you a short symphonic work probably the same one I sent Audiophile Neuroscience.

[gmgraves]

2 minutes ago, mansr said:

Indeed.

 

From the wrong fucking direction! How much wilful ignorance does it take to not see this?

 

I'm sorry Mansr. You're wrong! If you can't visualize the model, that's not really my fault. and if it is from the wrong direction as you assert, how come it works so well? HMMMMM?