Random Stuff About Surround Sound

[MidiMagic]

My how this thread has wandered!!

You turned your head.

 

[MidiMagic]

You know very well that QS vs Dolby matrix encoding is not the same. Look at your own quad matrix pages. I know you hate modern surround audio but really, much improvement has gone on since your record changer & DIY decoder. Do try to encounter some more modern changes and you will be rewarded.

The encoding equations are different because QS is based on 4-corners and DS is based on the LFRB diamond. But the encoded signals produced by an audio console capable of panning the sound in a circle around the listener will produce the same encode for both systems.

This is a vector plot of stylus motions in the record groove produced by either a QS position encoder or a DS position encoder. Notice that the QS vectors for LF, RF, RB, and LB are interleaved between the DS vectors for L, F, R, and B.

Note that the 4-corners encoders provided for each system do not produce exactly these vectors. The QS 4-corners encoder produces slightly different signals for L and R, while thre DS 4-corners encoder produce slightly different signals for LB and RB.

I do not "hate" the modern methods. They do not live up to my expectations.

- I have tried 5.1 discrete on audio stores and in theaters. It seemed to work much better in the theater. In one audio store, I watched a movie with fighter jets dogfighting. I heard the cogging: the sound of a fighter that just flew past the camera location suddenly jumped from the front speaker to the surround speaker on that side before continuing farther back. If I turn my head left just before that jet goes by, I hear a smooth path. I have the same movie on a DVD with Dolby Surround. The jet sound moved smoothly back no matter which way my head was turned.

I hear similar jumps in every discrete system from CD-4 to 7.1. Turning my head removes the cogging.

- It is possible to mix a discrete recording that does what I want. But they would have to compromised the discreteness by putting a delayed version of the signal panned to one side in a speaker on the other side. But I rarely hear it.

I have another goal. I want to make a recording that anyone can play without special equipment. This means a standard LP or CD and QS/DS encoding. No special doohickeys or esoteric players. All of these options are available:.

- It plays on a stereo or mono system.
- It can be put on AM or FM radio with no problems.
- It will play on all CD (or stereo phono) players.
- Most DVD players will play it in Dolby Surround (or in stereo, where it can go to a QS or DS decoder)
- Every sound will come from the intended pan position in DS or PL no matter how you turn your head.
- Surround Master or VarioMatrix can play it, putting panned sounds where they belong.
- A digital receiver can upmix it for 5.1 or 7.1.
- It can be digitally recorded on a PC in .wav or .mp3 format (assuming no pan compression).

If I still had it, the first quad mix I ever made (1970) does these things.
Almost every recording I create does these things.

What I do NOT want is "puddles of sound at the speakers".

 

[MidiMagic]

Interesting about cogging. Really not trying to flog our stuff or a point but our SST really has zero cogging. Walk around, sway side to side, rotate, the image is always consistent

So the image is stable no matter how you face or where you walk.

How do you keep a moving image from cogging?

 

[MidiMagic]

I partially agree with you about cogging but it can be greatly reduced by proper speaker placement. the attached is from the Lafayette SQ-W owners manual, and has long been my prefered speaker arrangement (long before seeing it in print). There are several causes for the effect that you describe. The first is "hole in the middle stereo" you get cogging even with stereo if the speakers are too far apart! Side imaging is not as good as front imaging so the effect is even worse to the sides. With the speaker arrangement shown I have no trouble hearing smooth pans. I admit that I may be unconsciously turning my head slightly with the pan, but so what it's easier than remaining in a rigid fixed position. Yes most Quad pans were done quickly so that the cogging is less noticeable.

That makes sense. The front speakers are closer together than the back speakers. Thus the left-right level panning works in normal human hearing for positioning all around that speaker layout.

I have heard only minor cogging with the speakers placed like that, or if you sit near the back.

 

[MidiMagic]

I can explain the cogging problem a little more:

The human hearing system essentially locates each actual source (in this case, a speaker) reaching the ears. It uses the values of level, timing, and phase to locate the source.

The system works with level panning when the sound is intended to be in front of or behind the listener.In this case, the signal from the speaker on one side usually reaches the ear on that side first, while the signal on the other side reaches the other ear first. The hearing system combines these two signals to form a stable image between the speakers.

When both speakers are on the same side, the hearing system detects two separate sound sources, but because both signals arrive at the ear on that side before signals from those speakers reach the other ear, the hearing system has trouble resolving the two images. It usually chooses the source that is louder or the one that arrives first. The system cannot resolve the two sources into one image. It takes the other source as an echo of the first.

When the levels change so the other source becomes dominant, the identification of the source changes to the other source. This is the cogging.

Dolby Surround and PL provide a delayed signal that reaches the listener's other ear from a surround speaker. This gives the hearing system enough information to form a side image from the two speakers. This is missing in other systems, including all other matrix and discrete systems.

 

[MagnumX]

When both speakers are on the same side, the hearing system detects two separate sound sources, but because both signals arrive at the ear on that side before signals from those speakers reach the other ear, the hearing system has trouble resolving the two images. It usually chooses the source that is louder or the one that arrives first. The system cannot resolve the two sources into one image. It takes the other source as an echo of the first.

If that were true, then how is it I can adjust my active mixer level combinations for the front wides (which is mains + side surrounds) for a pink noise test tone for the let's say the right side surround and by varying the amount of right side surround output from the front wide (placed along the right wall in front of the first row while the side surround is behind the first row) so that the pink noise tone moves from the right side surround speaker towards the front wide speaker and place the tone anywhere in-between such as directly alongside my front row as if the side surround were directly to the right instead of at 110 degrees azimuth?

According to what you're saying, I should either hear two separate sounds or just one of them, yet only the combination of the two (combined array) could appear in locations between the two speakers. There is no delay used for this, just an active mixer essentially just varying how much output come from the front wide versus the side surround. There is no output from any other speakers (pure discrete tone from an Atmos speaker tone, no matrix decoding or upmixing involved either, just pure pink noise coming from two speakers at the same time on the right wall in front of and behind my chair which is between the two sets of speakers). How do you explain this?

 

[chucky3042]

So the image is stable no matter how you face or where you walk.

How do you keep a moving image from cogging?

TSS isa time delay equalizer, so the arrival time of left and right and the rears is equivalent everywhere within the room. I suspect magnumx is actually very sensitive to side image. We all vary in our sensitivities, for example I am super sensitive to image in general but quote poor in detecting distortion.

 

[Soundfield]

 

[MagnumX]

You know what really solves a disagreement? Posting snobby quotes about feeling that have literally nothing to do with observations made other than point out one's own deep seated issues of inadequacy or irrelevance.

Perhaps the SM V3 isn't what I'm looking for since my hearing apparently isn't normal so I can't trust to hear it correctly.

 

[jaybird100]

You know what really solves a disagreement? Posting snobby quotes about feeling that have literally nothing to do with observations made other than point out one's own deep seated issues of inadequacy or irrelevance.

Perhaps the SM V3 isn't what I'm looking for since my hearing apparently isn't normal so I can't trust to hear it correctly.

My 73 year old ears aren't the best anymore, as well, but the SM still knocks my socks off, each and every time I fire it up. And that's anytime I listen to music, encoded or no, on my system. It still brings out subtleties and detail not heard otherwise.

 

[Soundfield]

Of course the SM is great but we all really need the flexibility of the long awaited Super Surround Pre-Amp. Next year please Chucky?!

 

[chucky3042]

Of course the SM is great but we all really need the flexibility of the long awaited Super Surround Pre-Amp. Next year please Chucky?!

Working towards it, but for volume market reasons we are prioritising the mini modules of a bunch of stuff first.....eg the 6 ch amp, mini preamp , encoder all in a SM sized box. Much of the work we are doing on these mini units will end up in the super surround pre amp

 

[J. PUPSTER]

My opinion on much of this is simply that there is no one way to listen to music. That is why we're here discussing Surround Masters etc. Also, we all have different acoustic environments, gear and expectations about how we want to hear the music. I personally don't feel just because so and so album's first stereo recording/mixing/mastering is the "go to-never to stray from" version (that's all just seen by me as one out of infinite possibilities) and no one will ever change my opinion of that. So when someone says, "that's how this album should sound as the absolute Gold standard", or some such, I start to question where that person is coming from. Trying out various versions/releases/mastering has cost me a small fortune; but some are very different and equally appealing.

 

[amco]

Seems to me that much of this brilliant technical analysis of cogging omits a major practical observation: so many (maybe most?) rectangular listening rooms site the Front L, Rs much closer together than their distance from the listener, while the Rear L,Rs are similarly close together, but usually much closer to the listener than the fronts. Thus quite obviously, the Front L and Rear L pair, also the Front R and Rear R pair are relatively the most spaced out of pairs, hence strongly susceptible to generate cogging with a smoothly rotating sound field image !?! This seems to me a common sense dominant factor in generating cogging of the side images in so many systems, irrespective of the techo pros and cons of decoders etc.

I have an irregular room of 6m x 8m x 3.13m ceiling, with a central listening position somewhat equidistant from all speakers, and in general cogging is NOT an issue.

PS: do listen to helicopters with both feet on the ground

 

[MidiMagic]

You can say or believe whatever you want, but what you two are saying about turning one's head or blurry imaging is absolutely not what I experience at all in the slightest. Imaging to my sides is sharp as a razor blade. It's BEHIND that is a bit harder to gauge the distance to something, but even then it's not even slightly blurry sounding or whatever you think you're describing. I've got a helicopter demo in Atmos that flies around the room, which I can have it play overhead or at ear level and it doesn't get blurry or ill defined as it goes around the room, but distance behind is harder to gauge compared to in front of me or to the sides. But the idea that the sides are somehow not sharp or distinct sounding is absolute nonsense. Perhaps you need to listen to some modern discrete surround recordings instead of QS/SQ records that have poorly defined surround channels?

Where did you get the app for your hearing system to resolve side images?

I have listened to modern discrete. My hearing system still finds the speakers instead of where the sound is supposed to be panned when sounds come from the side. I have to turn my head to hear the actual panning.

 

[MidiMagic]

If yo

If that were true, then how is it I can adjust my active mixer level combinations for the front wides (which is mains + side surrounds) for a pink noise test tone for the let's say the right side surround and by varying the amount of right side surround output from the front wide (placed along the right wall in front of the first row while the side surround is behind the first row) so that the pink noise tone moves from the right side surround speaker towards the front wide speaker and place the tone anywhere in-between such as directly alongside my front row as if the side surround were directly to the right instead of at 110 degrees azimuth?

According to what you're saying, I should either hear two separate sounds or just one of them, yet only the combination of the two (combined array) could appear in locations between the two speakers. There is no delay used for this, just an active mixer essentially just varying how much output come from the front wide versus the side surround. There is no output from any other speakers (pure discrete tone from an Atmos speaker tone, no matrix decoding or upmixing involved either, just pure pink noise coming from two speakers at the same time on the right wall in front of and behind my chair which is between the two sets of speakers). How do you explain this?

If your side wide is farther to the side (from your seat) in the L-R direction than the front wide, then the front panning feature of hearing is operating.

Either that or you have developed an app for your hearing system that the rest of us do not have.

Maybe it is a learned process from repeatedly hearing sounds that you already know the intended pan position of. For most people, it is intended to locate sounds enough so you can turn your head and see the sound producing device.

 

[MagnumX]

If yo


If your side wide is farther to the side (from your seat) in the L-R direction than the front wide, then the front panning feature of hearing is operating.

Either that or you have developed an app for your hearing system that the rest of us do not have.

Maybe it is a learned process from repeatedly hearing sounds that you already know the intended pan position of. For most people, it is intended to locate sounds enough so you can turn your head and see the sound producing device.

Is it really SO hard to believe that you perhaps it's not your hearing and you simply have set up a system that doesn't image correctly? If you listen to an Atmos album like Yello's new album Point, there are obvious and clear effects that move around the room in a rectangle. Even Alan Parsons' ON AIR album from the 1990s has him walk around the room from the left surround to the right surround and then forward to the right front speaker and then to the left to where the center speaker would sit (It doesn't actually use a center speaker). Do you truly believe that they panned these effects like that just for the hell of it because people can't hear them???

Do you honestly believe no one but me can hear the helicopter circle the room with the Dolby Atmos helicopter demo (either overhead or at ear level depending on the setting)? Why would Dolby even bother creating Atmos if human beings can't tell when something is off to their side???

If you have a friend walk around you in a circle saying something or humming the entire way, are you seriously telling me you can't flipping hear him when he walks off to your left side because there is no delayed signal coming from a speaker on the other side of you to tell your brain that he's there???? Or does he just turn into a giant wall of blurred pudding when he's talking off to your left? Does that even sound like it makes any kind of logical sense at all? Because I've never heard ANYTHING like that my entire life!

Now I have heard 5.1 (and that would apply also to 4.0) systems that didn't image for shite. Putting the surround speakers on either side of the couch is probably the worst configuration ever conceived. Due to the room, I have a 4.0 system set up like that upstairs with my Carver AL-III ribbon speakers (using Klipsch speakers on the side of the chairs pointed outward to reflect off the side walls). If I run the same demos using that system, there's a bit of a "hole" in the imaging between the Carver speakers and the Klipsch speakers about halfway between them with most material. Put a pair of front wide speakers around 45-55 degrees between them (playing a combination of front + side) and set the levels even and that hole will disappear like magic.

Downstairs, I have mains at 30 degrees in front of me, wides at 45 degrees on the side wall and the side surrounds at 120 degrees behind me on the side walls. I get a perfect circle of panning around me with a 5.1 game like Dragon Age Inquisition on my PS4 (i.e. rotate character with a sound producing object like a fireplace and the fireplace sound moves around me in a circle). There are no weak points on that circle. For a 7.1 decoding type base and Atmos and DTS:X, I have another set of side surrounds at 135 on the side and a set of rear surrounds at 155 degrees on the rear wall. Having the Dolby helicopter circle the room at ear level using those speakers produces a nice ellipse around the room. At no point does the helicopter "blur" or disappear. I probably couldn't tell you how far it was along the rear side wall (hard to gauge distance) as well as in the front (where I can look for the point where the sound is coming from as a reference, but it doesn't turn to "pudding" or mush either.

Overhead, I have the front heights at an azimuth of 35 degrees (screen is slightly in the way so they have to sit slightly over from the lower speakers), 120 degrees (directly above the side surrounds) and 155 degrees (above the rear surrounds). The top middle set has two sets of speakers on it (one facing forward towards the front row and one facing backward towards the back two rows, which technically has as many sets of drivers as the lower room then) and the helicopter circles the ceiling in a big ellipse at that height too. That demo is a test of the panning capability of your Atmos system. The helicopter should move around smoothly and without turning your head to hear it.

Now I'm in no way saying it's not possible some people can't hear that panning correctly due to ear/brain/training/brain tumor, etc., but Dolby wouldn't have even bothered with Atmos or DTS with X if the system didn't work. I have Atmos music albums that place sounds in space a couple of feet in front of me to the left or right in space between me and the front speakers even. It's like a phantom image hologram. I have an Atmos demo ("Silent") where a cart is being pulled from the back of the room straight down the middle of the room to the front of the room and it passes right through me like a ghost wagon.

Yello's album Point has a song on it called Big Boy Blues where about 2/3 through it, this buzzy synth sound hovers above the center speaker and then flies straight down the middle of the room to the center back of the room about 1 foot over top of my head like a missile. You can hear it buzzing its way along that path as if a drone just flew over your head for real. It's absolutely awesome sounding. Until Atmos, I've NEVER heard anyone place a sound in a room quite like that even though technically they could have done with 7.1 or even 5.1. I know that because I can turn my system into 7.1 or 5.1 and play the same song and it STILL moves along that path (just not as far back into the room with 5.1) as the sound is 100% in the lower speakers (no heights used). Movies didn't tend to place sounds in the middle of the audience because giant arrays in theaters wouldn't produce a pin-point focused image and it's even more distracting than regular surround, but I've heard some sounds used in some Atmos movies like that hear and there.

The one Atmos demo called "Nature's Fury" has the narrator bragging they can place a sound ANYWHERE in the theater now and the demo proceeds to do just that (showing a hundred little speakers on the screen that light up as the sound starts moving and moves with it until it goes into the room itself towards the back and then circles around and comes back onto the screen again and then blows up into all kinds of crazy sounds from a helicopter flying overhead to kids falling into a swimming pool to another kid saying, "Come on guys, let's go!" and a red light shoots off to the left and so does his voice while it moves to to the left of me (passing through every point in-between).

Another demo called "Shattered" has a baseball break a window and fly across the room in slow motion past your right ear (it even says this with a narrator right before it does it) while shards of glass fly overhead and then a big chunk hits a lamp in front of you and breaks into more pieces while you hear the kids that are responsible running away at ear level outside the heading away. There's one called "Unfold" that unfolds this plastic/glass like thing into the back of the room and then shoots around at ear level in a big circle followed by tiles snapping into in place overhead front-to-back. Another demo called "Leaf" has wind blowing from all kinds of directions knocking a maple seed off a tree and it flies around the room to the wind sounds blowing it this way and that and then falls into a pool on-screen with the sounds all lining up right where you see it.

NONE of those demos would work properly if panning through the sides or behind or overhead was some kind of an issue. I really think some of you haven't heard what these kind of systems can do (when set up properly). It's almost like a holodeck for sound.

 

[par4ken]

Putting the surround speakers on either side of the couch is probably the worst configuration ever conceived.

Wrong, Wrong,Wrong!!! I've always listened to Quad in some form since 1972 and that is by far the best setup for the typical living room! I've tried every possible configuration over the years. Do you sit in an armchair in the middle of the speakers like some drawings show! That is totally impractical! Speaker placed behind you sound best if you are in a small room with the speakers close together, The QS-1 synthesizer sounds good with such a set up, but does almost nothing in a larger room. Most of my listening is to enhanced stereo via the S&IC or Vario-Matrix (surround), the stereo mix is pulled apart and spread around the room, that is the most effective way to hear it. To just listen to regular stereo I would just as soon listen to mono! I don't notice any cogging effect with my speaker setup.

 

[MagnumX]

Wrong, Wrong,Wrong!!!

Wow. What a great argument.

I've always listened to Quad in some form since 1972 and that is by far the best setup for the typical living room! I've tried every possible configuration over the years.

Did you ever try adding a passive set of front wide speakers using a mere active mixer to lower the angular gap between surrounds (6 instead of 4?). No, I didn't think so. You obviously never tried the "best" setup. Perfect 360 sound without all these cogging issues.

More to the point, you cannot get proper sounds BEHIND you if the surround speakers are directly to your sides. There's no way to get a 360 degree circle and you'll still have imaging problems on the side wall between the mains and side surrounds as that angle is too large. By putting the surrounds at 110 degrees and putting a set of "helper" front wides to lower the angle on the side wall, you get a nice 360 circle, which I can prove with a PS4 game by rotating in a circle (the fireplace roaring or whatever goes in a perfect circle around me with no gaps).

Do you sit in an armchair in the middle of the speakers like some drawings show! That is totally impractical!

No, I actually have three rows of armchairs.

Speaker Angles Used (Ignore everything behind SR/SL and the overheads for this discussion as they aren't needed or used, just Left/Right, FWL, FWR and SL and SR.

Room View in 360 degrees (Not totally up-to-date, but you get the idea).

 

[Owen Smith]

I have a 5.0 system because that is all I have space for, I can't even fit a sub in. The rear speakers are on the back wall on wall brackets laid on their backs firing up at the ceiling, because it's the only way to have rear speakers that don't fire straight over my head. There is literally no way to fit any more speakers into the room, so my speaker placement is put them in the only places there is space for them and then accept the sound they produce. My only other options are to switch off the surround system, or spend a huge amount on a bigger house (that I otherwise don't need).