Soundstage and imaging

[MattHooper]

Words. Just words. No information.

Sorry...were you trying to communicate something? I don't understand just words.

 

[Emlin]

Sorry...were you trying to communicate something? I don't understand just words.

Clearly not.

 

[MattHooper]

Clearly not.

Wrong side of the bed this morning?

 

[Emlin]

I am now ignoring you and your irrational rants.

 

[MattHooper]

I am now ignoring you and your irrational rants.

Sounds good. I appreciate it.

 

[STC]

Thats the transition, distance where perception changes and brain lifts the phantom out of all the noise in the room. The sound gets your attention

Anechoic chamber sounds like the best way to achieve this…..but anechoic chamber sound would be lifeless and unexciting without the lateral reflection, just like many over-damped audiophiles room.

 

[STC]

It's all about accurately reproducing the reverb on the recording and not letting that be swamped by the reverb of your room.

Anechoic chamber?

 

[Emlin]

Anechoic chamber?

No, because the recordings aren't mixed with the expectation that they will be replayed that way. The circle of confusion again.

 

[STC]

No, because the recordings aren't mixed with the expectation that they will be replayed that way. The circle of confusion again.

Exactly, room is part of the equation during playback for more realistic/natural presentation.

In stereo, only the frontal ambiance is included and that too very limited and the rest is expected to be generated by the room or via additional speakers. I am getting confused how the simple dimension ( mostly frontal) called soundstage created by the two speakers in stereo now invokes room interaction. Isn’t that a separate topic?

 

[Emlin]

Exactly, room is part of the equation during playback for more realistic/natural presentation.

In stereo, only the frontal ambiance is included and that too very limited and the rest is expected to be generated by the room or via additional speakers. I am getting confused how the simple dimension ( mostly frontal) called soundstage created by the two speakers in stereo now invokes room interaction. Isn’t that a separate topic?

Stereo means 3D. The reverb is in the recording. Reproduce that. Get the room out of the way, reasonably.

 

[STC]

Stereo means 3D. The reverb is in the recording. Reproduce that. Get the room out of the way, reasonably.

If stereo means 3D then how about binaural or crosstalk cancelled playback like BACCH?

 

[antcollinet]

Words. Just words. No information.

You need to learn how to have a debate in a civilised way.

This is not it.

 

[tmuikku]

To me the 3D part in stereo is envelopment. When you listen close enough so that hearing system attaches to the phantom image, the room sound gets its own neural stream and envelopment happens. Griesinger has found this out and says envelopment cannot happen if brain cannot pick up direct sound to its own neural stream, there must be separate neural stream for both. Contrary, when you listen too far there is only one perception of sound, direct soubd and room sound are mixed together as one, a hazy blob of sound somewhere speaker direction.

Basically, taking Griesinger work as basis you can be rooted to sound, after finding the transition woth your setup you are now able to listen various aspects of your system. You'd be able to evaluate envelopment, quality of your room sound. Anechoic would miss this completely, so its bot the same I think, never been to anechoic chamber.

It's very powerful thing to be able to listen both sides of critical distance with information by Gtiesinger in back pocket. It's possible to reason about speaker DI, or significanse of various cta2034 graphs, and so on.

Ok, this is speculation but here is how I have used the knowledge to my advantage with my system: For example, you get the phantom center with the listening test alright, but with music the sound doesn't seem to surround you, weight of envelopment seems front of you. By Griesinger you can be sure there should be envelopment, but its just not there, or is masked by direct spund because bulk of it comes from frontal direction? Ok what you do, since the crotocal distance depends on the room sound level, at least seems so, its logical to think that the lack of envelopment is due to too loud early reflections, and too low reflections that come from all directions. Now, what you do is try to change this balance: delay / attenuate the earliest loud reflections. If at all possi ble make reflections that come next and behind you louder.

I moved my system to a corner, which made previously slopsided boundaries more symmetric, almost doubled earliest side reflection, and there is sofa between speakers to reduce reflections from front, and so on, changed drection of earliest lateral reflections. This seems to be enough difference to have bit better envelopment than before. But as I said it's just speculation and could be that all I hear is change, and not necessarily an improvement. But, the main power is that I now know how envelopment happens and when I can hear it and hownit sounds like, a requirement to do anything out it.

Hope it helps

 

[antcollinet]

I am now ignoring you and your irrational rants.

And that will be your loss.

 

[tmuikku]

If stereo means 3D then how about binaural or crosstalk cancelled playback like BACCH?

Hi, might be so, but still you'd need to be close enough to actually hear it I think. Too far and room sound mixes the information and perception is basically just noise. Perhaps you already are close enough, but as you perhaps notice this is cruzial information both of us must know and understand how these things sound like, and which sound one is talking about It really seems binary, brain either gets it or not.

 

[STC]

Hi, might be so, but still you'd need to be close enough to actually hear it I think. Too far and room sound mixes the information and perception is basically just noise. Perhaps you already are close enough, but as you perhaps notice this is cruzial information both of us must know and understand how these things sound like, and which sound one is talking about It really seems binary, brain either gets it or not.

I think there could be miscommunication here. My understanding of 3D and envelopment is different. For me 3D is to mean more realistic lifelike experience of imaging of the sound in space from stereo recordings. Once done correctly with crosstalk cancellation the listener hear the difference like in this example when played over loudspeakers.

And envelopment is something that stereo cannot reproduce in full as it was not captured in the recordings except the limited frontal reverbs. I use actual concert hall or space impulse response to create the envelopment via 26 speakers from 45 degrees onwards towards the back. It creates the artificial envelopment from anywhere from 0.3 to 4.4 second RT with different character like a concert hall or hard surface room like here

 

[audiofooled]

Finding the right distance between the loudspeakers is also highly critical, too large a distance and you end up with a washed-out sounding phantom image. When you find an optimal distance between the two speakers, the phantom center can sound almost as solid as if a physical center speaker is used in the setup. And with that, you will know that you have "anchored" the sound from the two loudspeakers in the stereo setup and that they are reproducing a unified stereo image, and by that, pretty much everything including the finer details that paints the three-dimensionality (if the recording contains such information) will also be optimized and have better "focus".
When the "right" distance has been found for optimizing both the direct sound ratio and a distinct-sounding phantom image is found, toe-in can be used to fine-tune it even further.

One straightforward method for finding the optimal distance between loudspeakers, also optimal toe in that I would suggest is by using transients such as this:

To elaborate, note that this kind of waveform contains pitch down sinewave starting from about 17kHz to about 44Hz. However, if you look closely at the time related to the mouse cursor, it appears that the signal pitches down from 17kHz to about 90Hz or so in 2-3 milliseconds. This goes down way too fast for us to perceive it as anything but a "click", with a substantial weight of mid-bass.

Optimal setup should have a very clear and pinpoint focus on that. A "click" should be very tiny, floating exactly in the middle of phantom center, augmented by very focused and strong mid-bass. The rest of the waveform contains low frequencies and on a system which is capable enough, you should get a very distinct and focused "kick", followed by envelopment of lowest of frequencies and soft decay. Low frequencies are long in duration in comparison but should never mask the higher frequencies. Subjectively, it should be perceived all at once, but high to mid frequencies should never be masked or loose focus. Also, they should be loud enough in comparison to lows.

You can start wider with no toe in, and then gradually decrease the distance and introduce some degrees of toe in. This will depend on speaker directivity. The "sweetspot" is usually where mid-bass is strongest with the same level of amplification.

It is hard to describe, but once you get it right, what you hear can be an "aha" moment. On the headphones, the pinpoint click would obviously be right in the middle of your head. On loudspeaker system, it should be even more distinct right in the middle of the phantom center. To test the image stability, you can move yourself out of the comfort zone of your MLP and see if you loose any focus.

To me, this method is all in one to show what your loudspeakers are doing and what your room is doing. It shows direct to reverberant ratio in a very distinct and simultaneous manner.

When looking at pictures of people's HiFi systems, many people seem to have a somewhat large listening triangle where the ratio of the direct sound is probably pretty low vs their room reflections. It's as if they let the room size dictate how far away they sit from their speakers, almost as if it's a rule that a fairly large room is the deciding factor of how large the listening triangle ends up being, and that the listening position must be right against the wall on the opposite side of the room.

I find it funny that usually there's so much gear in between the speakers that they can't be setup any closer, form over function

 

[tmuikku]

I think there could be miscommunication here. My understanding of 3D and envelopment is different. For me 3D is to mean more realistic lifelike experience of imaging of the sound in space from stereo recordings. Once done correctly with crosstalk cancellation the listener hear the difference like in this example when played over loudspeakers.

And envelopment is something that stereo cannot reproduce in full as it was not captured in the recordings except the limited frontal reverbs. I use actual concert hall or space impulse response to create the envelopment via 26 speakers from 45 degrees onwards towards the back. It creates the artificial envelopment from anywhere from 0.3 to 4.4 second RT with different character like a concert hall or hard surface room like here

I understand you Yeah the envelopment from stereo is limited, but to get any one has to be close enough. Artificially created with multiple speakers, I'm not sure how it translates to perceived sound but even in that case I would imagine one has to be closer than critical distance to all speakers in order to suppress perception of the local room. Does this make sense to you with your setup and what you describe?

 

[STC]

I understand you Yeah the envelopment from stereo is limited, but to get any one has to be close enough. Artificially created with multiple speakers, I'm not sure how it translates to perceived sound but even in that case I would imagine one has to be closer than critical distance to all speakers in order to suppress perception of the local room. Does this make sense to you with your setup and what you describe?

Critical distance can be determined with a SPL meter but even then it depends on the genre you are listening. For some you want more room sound and for others less.

Most studio recordings uses artificial reverbs as they are often recorded close miked or in addy room. There’s video comparing natural and artificial reverbs to see if the recording engineers could tell the difference. If I find it I will post it here or in a new topic as this is not relevant to soundstage and imaging.

 

[tmuikku]

Hi,

Critical distance can be determined with a SPL meter

this seems too simple. Actual critical distance in acoustics is defined as distance where direct sound pressure equals room sound pressure in level (all reflections combined). I'm not sure if the perceived critical distance is the same distance, likely not. The reason I think it is so because I was pointed out elsewhere that at low frequencies there is no difference, its all room sound and it's not possible to perceive direct sound, and at very high frequencies there is plenty of time for brain to process direct sound before reflections come in regardless of D/R. More over, loudspeaker DI varies with frequency as does room acoustic properties.

Now, since the perceived critical distance seems to be real, it must be there is some frequency bandwidth between the extremes, somewhere in the midrange. Griesinger says that its harmonics of sounds that need to be there in phase for brain to lock in and at least with speech he mentions bandwidth around 700Hz-4kHz contains the important harmonics.

Some people seem to advocate wide baffle speakers, they likely prefer the close sound. While others like smaller ones, perhaps they dig the far sound. 700Hz wavelength is roughly 50cm long, speakers smaller than this would have relatively low DI at 700Hz, speakers bigger than it would have greated DI, which might mean how far away the transition happens. Gradient speakers could be small and still have relatively high DI, some rejection towards earliest reflections so exceptions of course. Mo confusion, unless one is aware of the perceived critical distance and what to do with it.

depends on the genre you are listening. For some you want more room sound and for others less.

The perceived critical distance is ultimately limited by the playback system in a way that you must be at close distance in order to hear what is on the recording, to prevent local room messing it up. Assuming the playback is otherwise good enough not to mess it up as well. Like you say the recording might already have messed up phases intentionally or unintentionally, in order to manipulate the perception. And yeah you are absolutely right some material sounds better far away, can be quite annoying close up with hard panning instruments and such. More over, it might be some preference we have accustomed to. Many people seem to like the far sound, for some reason, while I like the close sound for some reason. Might be due to some time spent with recording and mixing which has provided enough exposure for the close sound in order to fond it instead. Both are fine, I just like music

Most studio recordings uses artificial reverbs as they are often recorded close miked or in addy room. There’s video comparing natural and artificial reverbs to see if the recording engineers could tell the difference. If I find it I will post it here or in a new topic as this is not relevant to soundstage and imaging.

yeah anything that is baked on the recording, real or artificial, needs the close distance to deliver as intended, otherwise the local room messes it up and brain considers it noise no matter whats in there. Perhaps the engineers were not interested in close sound and always listened far away, or intended the product be listened far away. Like those recordings with crazy hard panning, engineer must have been listening far away I think in order not to vomit. To me this seems more ignorance than logical thing to do though, its perfectly possible to make recordings which sound good on both perceptions, I think. Well, artistic freedom to all. Its not my job to judge whats good or bad, everyone do their own thing, I just sit around the audible critical distance and lean back or forward depending on which I like better and draw hasty conclusions about things

Anyway, in order to be able to switch between the two perceptual "effects" its helpful to know how each sounds, how they affect perception whats on the recording and most importantly how to switch between the two. I might be completely wrong with all the speculation how and why and what, but still the perceptual change is real, for some reason, and is very important shaper of stereo sound.

edit. hmm, if speakers are all around its not possible to switch distance I think, either the speakers are close enough, or far enough, moving closer to front speakers would make you further from back speakers. Have you experimented with this, does it make any difference? How big your surround setup is, in diameter?