What exactly is "imaging" ?

[DimitryZ]

Yes, imaging means that you get - at least - a clear sense of where - left to right - various sound sources are placed in front of you. In better cases you also sense the relative distances and the surrounding acoustic being from 'behind' the main sources.

However the recording is critical, not just the speakers, their locations, and the acoustics of your listening room. So a lot of things have to be 'right' for this to happen.

A problem is that speakers are generally designed to work in a room. So 'outdoors' (aka anechoic chamber ) they may not work so well as in the 'right kind of room'. That said, I've personally tended to associate good '3D' imaging with ESLs. And your ears and speakers being in just the right places.

The effect is probably irrelevant to a lot of studio rock/pop/etc. But make a *big* difference to something like listening to a BBC Prom concert! Enhances the 'being there' feeling.

Certainly, the 63 and its' many derivatives, being acoustic analogues of phased array radars (though designed for a spherical as opposed to planar waveform) would be ideally situated to produced the best imaging.

I always enjoyed this aspect of the speaker when I owned it. My were modified by Electrostatic Solutions (which included the sparse weave sock) and were on stands - facilitating the mirror alignment as Jim recommends.

 

[RJohan]

Height and to some extent depth have to be speaker with the room effects and the same equipment in another house and listener position will behave differently

From my experience it's just that. It happened to me in a previous listening room/set up. The equipment was a lot of olive colored Naim boxes (bashed above in this thread) and big JBL monitors (not renowned for sound staging). On some recordings it was obvious that one could hear the impression of height in the recording venue, reaching from floor to ceiling in the listening room. No pinpoint accuracy as in 'this guy is above that', though. Probably a fortunate relationship of angles and phase in the relationship between direct and reflected sound in the listening room that mimic that in a real listening room.

 

[DimitryZ]

From my experience it's just that. It happened to me in a previous listening room/set up. The equipment was a lot of olive colored Naim boxes (bashed above in this thread) and big JBL monitors (not renowned for sound staging). On some recordings it was obvious that one could hear the impression of height in the recording venue, reaching from floor to ceiling in the listening room. No pinpoint accuracy as in 'this guy is above that', though. Probably a fortunate relationship of angles and phase in the relationship between direct and reflected sound in the listening room that mimic that in a real listening room.

It seems that actual height reproduction is not possible with a stereo system as no height information is recorded with a classic stereo microphone setup and no height can be reproduced with two stereo speakers.

Height imaging requires specialized microphone setups, processing and Atmos compliant replay system.

What you may have heard is frequency dependent ceiling bounce from a speaker with a non-uniform vertical dispersion.

 

[davidsrsb]

It has to be a lucky accident, Only purist recordings eg binaural can hope to actually record height bounce information. Most multi-mike classical and all studio pop/rock and jazz never had the information in the first place.

 

[RJohan]

What you may have heard is frequency dependent ceiling bounce from a speaker with a non-uniform vertical dispersion.

Yes.

An interesting effect I've noted, not related to this. When looking on pics/vids of classical recordings one can clearly see that the mic's are placed high above the conductor (where no listener is in the real world). Yet, usually, we hear the orchestra in the horisontal plane in front of us. On a few occasions when I heard recordings made by the Swiss Radio, it actually sounded like I was placed high above the orchestra and looking down on them. The sound was still placed between the speakers, but it really 'felt' like I was above!

The habit of placing the mic's high up gives quite a different frequency balance to what is recorded vs when you are in a seat at the music hall. Noted, among others, by Floyd Toole:

'In the day, and now, recordings of classical orchestras were often made with microphones placed in elevated positions above the violins. These instruments radiate strong high frequencies upwards, not towards the audience in a concert hall. They are heard by the audience, but after reflection and reverberation in a physically large space - they add "air" to the illusion. The microphones were relatively close and in a position to collect more high frequency energy than is likely to be heard in the audience, certainly in the ground level seats. It turns out that loudspeakers with slightly attenuated upper-mid/lower highs sounded better. So, instead of listening to neutral monitors and adding a little EQ attenuation in the offending frequency range, they decided to listen to the flattering monitor speakers and leave the excessive highs in the recording.'

From: https://www.audiosciencereview.com/...e-the-classical-music-pros-using.12225/page-9

 

[RJohan]

It has to be a lucky accident, Only purist recordings eg binaural can hope to actually record height bounce information. Most multi-mike classical and all studio pop/rock and jazz never had the information in the first place.

Yes.

Btw. Soundfield mic's also captures height, but I'm not sure there are any commercial recordings where it's preserved.

 

[Darren L]

I've always thought of 'imaging' as the placement of instruments and voices within the soundstage.

 

[tuga]

The KEF Carlton 2s sounded great out of doors but it was more like listening to a beautiful, 2-D sound painting than a 3D stage performance. ( maybe imaging is just not a strong point of my speakers and gear).

Real stereo (stereo that is capture by two mics as opposed to one fabricated in a mixing desk) is one-dimensional.

Stereo = 1D​

What it does is create the illusion of positioning one or several phantom images somewhere between one speaker and the other.
This link shows how different microphone setups produce distinct positioning of instruments/sources/images: http://www.sengpielaudio.com/Visualization-ORTF-E.htm

We get a perceived impression of soundstage "depth" and of a phantom image being closer or more distanced from the cues in the recording, such as reverb, high frequency roll-off, detail, delay, etc. as well as spatial cues (recreating the acoustics of the original venue where the recording took place).

The listening room boundaries can produce "colourations" which are perceived as widening of the phatom images, increased "spaciouness" or "envelopment".
Dipole speakers when well setup can enhance the sense of depth.

There is no heigh information in stereo, nor there is info regarding placement in the vertical plane.


Stereophile has a few helpful definitions in its Audio Glossary:

imaging The measure of a system's ability to float stable and specific phantom images, reproducing the original sizes and locations of the instruments across the soundstage.

phantom image The re-creation by a stereo system of an apparent sound source at a location other than that of either loudspeaker.

stereo imaging The production of stable, specific phantom images of correct localization and width.

soundstaging, soundstage presentation The accuracy with which a reproducing system conveys audible information about the size, shape, and acoustical characteristics of the original recording space and the placement of the performers within it.

spacious Presenting a broad panorama of ambience, which may be wider than the distance between the loudspeakers.

 

[tuga]

I'd like to add that listening outdoors, whilst a less pleasing experience, will result in a more accurate reproduction of the recorded signal.

 

[earlofsodbury]

Good summary; the flipside of stereo's 'smoke-and-mirrors' is human psychoacoustics, and most especially the brain's astounding ability to interpolate information not present sonically, which of course is also how it can be 'tricked' by various sensory phenomena, as well as the qualitative impact of emotional responses, current state-of-mind, expectation, habituation, &c.

 

[Mike Reed]

...spacious....

Now that's a very useful and communicative adjective for hifi use. It almost encapsulates the other terms, at least in concept.

 

[cromodora]

Imaging.
When you hear music in your listening area detached from stereo speakers that look like dumb furniture in the background as if they have nothing to do with it.
While vivid sonic images are conjured up in front and around you.
The effect is not just speaker dependent.
The whole playback chain has to be good enough.

 

[Tony L]

There is no heigh information in stereo, nor there is info regarding placement in the vertical plane.

This is a topic that fascinates me and I think was part of my ongoing shift away from conventional big multi-driver speakers. There is no doubt some albums on some systems give a unmissable sense of height. As an example try the ‘Someday My Prince Will Come’ album by Miles Davis. It is a brilliant album and I’d not audition any component or change without playing it. On some systems Miles’s close mic’d and astonishingly present trumpet comes from way above the speaker plane, really high up in the air. Try it. It is a really odd effect that I’ve heard on many, many entirely systems in many different rooms (I’ve had this album for 30 years or more). It is an album I’ll often play on other people’s systems, at dems etc, so a far wider scope than my own kit/taste in audio.

I have first hand recording studio experience etc; I understand how mics work, I understand a fair bit about mic positioning, outboard FX (which would be very thin on the ground when this album was recorded in the early 60s) etc, so I agree fully with the ‘there is no height information in stereo’. I accept that as fact, yet the phenomenon clearly exists, so what is it we are hearing? My guess is a combination of phase error and the for some reason widely tolerated ‘tweeter at the top, mid band in the middle, bass unit(s) lower down the cab, port at the bottom’ type speaker design. A design I now consider flawed, and the more drivers the more flawed it becomes. Phase error on recordings is a very confusing topic and certainly exists on pretty much any multi-mic recording, so this may be a combination of imperfect recording phase and multi-driver speaker playback. I don’t know, but certainly some recordings can generate an impression of real height in some scenarios, so I’m curious as to explanations/theories.

Folk should give Someday My Prince Will Come a go, it is a truly great album so nothing to lose, and I’ll be interested if anyone hears the height thing I describe.

PS One thing that I hate with a passion is piano mic’d in the way described upthread with regard to the Kate Bush album. I can’t bring that particular track to mind, but even the wonderful ECM are guilty of this ‘giant stereo piano the size of a stage’ thing at times, and on some big multi-driver speakers the thing invariably slopes (right hand high, left low) and sounds like the stage isn’t level. One often fears the piano will roll off.

 

[tuga]

This is a topic that fascinates me and I think was part of my ongoing shift away from conventional big multi-driver speakers. There is no doubt some albums on some systems give a unmissable sense of height. As an example try the ‘Someday My Prince Will Come’ album by Miles Davis. It is a brilliant album and I’d not audition any component or change without playing it. On some systems Miles’s close mic’d and astonishingly present trumpet comes from way above the speaker plane, really high up in the air. Try it. It is a really odd effect that I’ve heard on many, many entirely systems in many different rooms (I’ve had this album for 30 years or more). It is an album I’ll often play on other people’s systems, at dems etc, so a far wider scope than my own kit/taste in audio.

I have first hand recording studio experience etc; I understand how mics work, I understand a fair bit about mic positioning, outboard FX (which would be very thin on the ground when this album was recorded in the early 60s) etc, so I agree fully with the ‘there is no height information in stereo’. I accept that as fact, yet the phenomenon clearly exists, so what is it we are hearing? My guess is a combination of phase error and the for some reason widely tolerated ‘tweeter at the top, mid band in the middle, bass unit(s) lower down the cab, port at the bottom’ type speaker design. A design I now consider flawed, and the more drivers the more flawed it becomes. Phase error on recordings is a very confusing topic and certainly exists on pretty much any multi-mic recording, so this may be a combination of imperfect recording phase and multi-driver speaker playback. I don’t know, but certainly some recordings can generate an impression of real height in some scenarios, so I’m curious as to explanations/theories.

Folk should give Someday My Prince Will Come a go, it is a truly great album so nothing to lose, and I’ll be interested if anyone hears the height thing I describe.

PS One thing that I hate with a passion is piano mic’d in the way described upthread with regard to the Kate Bush album. I can’t bring that particular track to mind, but even the wonderful ECM are guilty of this ‘giant stereo piano the size of a stage’ thing at times, and on some big multi-driver speakers the thing invariably slopes (right hand high, left low) and sounds like the stage isn’t level. One often fears the piano will roll off.

I have that Miles album.

I think that it is a question of perception. Might have to do with tweeter dispersion characteristics as well as ceiling reflections, I can't say for sure.
But it's just an effect/distortion, it's not real in the sense that the sound is higher/vertically wider. Also we expect the kick drum to be on the floor and the vocals to be at 1.5-1.7m...
Yet, by manipulating phase (in fake stereo or a stereo mix) it is possible to have sounds above the speakers, or to the side of the speakers.

This test works best with heapdhones but you can hear/perceive some degree of effect with speakers too:

https://www.audiocheck.net/audiotests_ledr.php

The Test Files
You will now be testing your stereo system and room acoustics for correct imaging. If you have any problem reproducing the LEDR test, look for interfering room surfaces in the direction of the distortion.

UP paths, Left and Right. The sound should begin at about eye level and then travel as straight as possible up to one or two meters above the loudspeaker. Use the Left and Right paths to check for symmetry. If the sound does not rise up from your loudspeakers, try using high quality headphones instead. If headphones work, your loudspeakers and/or listening environment are at fault. If not, the pinna transform embedded into the test signal is possibly too different from your own pinna transfer function; the LEDR test will then fail in this particular case.

OVER. The sound should begin at one speaker and travel in a smooth arc to the other speaker, from left to right and then return back to the left. The arc should be unbroken, smooth and symmetrical. The top of the rainbow should be as high as the Up signals.

LATERAL. This signal tests for conventional left-to-right stereo imaging. Since a speaker's acoustic center may not be its physical center, you should use the Lateral test to adjust your speakers until the sound traverses a 60 degrees angle from the listener's point of view.

BEHIND. This signal moves from behind the left to behind the right, then back behind the left again.

 

[tuga]

Here's a good illustration of how stereo works:

 

[Tony L]

Here's a good illustration of how stereo works:

Looks overly simplistic to me. We need to think of the time domain too. The distance from the mic of the various sound-sources and their differing reflections in the acoustic space in which they are recorded is captured and certainly appears to be information human brains can decode.

 

[tuga]

Looks overly simplistic to me. We need to think of the time domain too. The distance from the mic of the various sound-sources and their differing reflections in the acoustic space in which they are recorded is captured and certainly appears to be information human brains can decode.

I wrote about that in my first post:

We get a perceived impression of soundstage "depth" and of a phantom image being closer or more distanced from the cues in the recording, such as reverb, high frequency roll-off, detail, delay, etc. as well as spatial cues (recreating the acoustics of the original venue where the recording took place).

The listening room boundaries can produce "colourations" which are perceived as widening of the phatom images, increased "spaciouness" or "envelopment".
Dipole speakers when well setup can enhance the sense of depth.

 

[tuga]

This might interest those who listen predominantly to studio mixes:

Stereo Image Trickery With PC Plug-ins

https://www.soundonsound.com/techniques/stereo-image-trickery-pc-plug-ins

There's never been a bigger choice of PC software that can enhance the spatial characteristics of your mixes than there is now. The options range from simple stereo-widening plug-ins to make your mixes seem 'bigger' and pseudo-stereo tools to turn mono sources into stereo destinations, through to sophisticated 3D tools that can shift sounds beyond your stereo speakers and move them around you in real time.

 

[Jim Audiomisc]

Yes, the diagram is clearly too simplistic. The reality is that we only have two ears and can't hear 'distance' in a simple way *even when listening at a live performance*. Instead, our brain infers it from the direct/reverb/(apparent)direction characteristics and having become familiarised with room acoustic effects.

Thus the usefulness of speakers and listening room with a high direct/reflected delivery. This reduces the 'confusing overlay' of the listening room's effect and allows you to hear the direct/reflected patterns of the recording or broadcast.

The skill here is in large part that of the producer who laid out and balances the mics as suitable for a venue. Or in some cases how that 'fake' an acoustic to give the impression of depth, etc.

 

[tuga]

Yes, the diagram is clearly too simplistic. The reality is that we only have two ears and can't hear 'distance' in a simple way *even when listening at a live performance*. Instead, our brain infers it from the direct/reverb/(apparent)direction characteristics and having become familiarised with room acoustic effects.

Thus the usefulness of speakers and listening room with a high direct/reflected delivery. This reduces the 'confusing overlay' of the listening room's effect and allows you to hear the direct/reflected patterns of the recording or broadcast.

The skill here is in large part that of the producer who laid out and balances the mics as suitable for a venue. Or in some cases how that 'fake' an acoustic to give the impression of depth, etc.

In what way is the diagram too simplistic?
In my view, if the sources were recorded and reproduced in free-space (e.g. outdoors) that is exactly what would happen.

Interestingly, research seems to indicate that most people prefer less direct / more reflected sound (for one it helps the speakers "disappear" and increases "spaciousness" and widens the images), but I agree that narrow directivity and attenuated or diverted side-wall reflections will result in a more accurate reproduction of the signal (particluarly important when listening to classical music because it reduces the overlaying of listening room sound above venue cues).