Rear surround speakers sound coming from front

[zainframe]

Hi All,

I have been having this issues for years and still have not gotten an acceptable solution:

I am running a 7.2 (sometimes 5.2.2 for Atmos sources) and the audio from the rear speakers sounds like it is coming from the front. This has been going on for a few years with 3 receiver changes and 3 sets of rear surround speaker changes (I have also tried a set of bipoles without any positive result). I am almost sure it is a room acoustics/speaker placement issue and not something related to:
1) Phase
2) Receiver settings
3) Wiring

From my browsing and response from forums this looks like a psycho-acoustic effect related to speaker placements (front rear reversal/cone-of-confusion effect) but I have tried to position the rear speakers the best I could. As you can see from the pictures- there is a door on the right rear side of the room giving me no choice but to put the rear speaker close to the center.

The speakers have been moved up/down/left/right as much as I can (as mentioned the door is preventing me to put it nearer to the corners), also tried pointing them to all directions. So far the only positive results I got is by moving my sofa very close to the rear wall/speakers making it about 3.8feet away from the speakers. This helps a bit where the effect is less but it is not 100% workable and I cannot move it any nearer to the wall for various reasons. I noticed the farther the listening position is from the rear speakers the more prominent the effect.

As you can see from the pictures the room is decently acoustically treated and I have also tried putting temporary drapes on various places on the walls etc. The walls are concrete.


This has also been shared on AVS Forums (very helpful bunch but still nobody could provide a workable solution yet)

My gears are:
Onkyo RZ900 (will be Denon X6400H soon I hope)
Polk RTiA7 fronts
Polk C5 centers
Polk RTiA1 side surrounds
Polk RTiA3 rear surrounds
4x Polk Monitor 30 front and back Atmos height speakers (mounted on the ceiling corners, now only front height working as the RZ900 does not have enough channels to drive the rear height)
2x SVS PB-1000 subs

Thanks everyone!

 

[agarwalro]

Welcome to the forum. That is a very nice setup and well arranged room. Love the Lego behind the couch.

IMO, you're forcing 7.x.x in a room suited to 5.x.x. The rear surround are meant to be 5-7 ft. behind the listening position and 3-5 ft. above ear height. (I feel the side speakers are low too, but, they don't bother you, so, back to the rears.)

You're sure there's discrete 7.1 and not some matrix processing mode engaged?

Does the front/rear confusion happen even if the rears are disconnected?

Have you tried turning the rear surround trims way down (almost to the point of being inaudible) and then turning them up slowly? In effect, you'll be taking them out of the mix and slowly bring them back in without overwhelming the front soundstage.

 

[lovinthehd]

I'd suggest the same as agarwalro, use the trims (levels) for the surrounds to find your sweet spot. You are a bit close to the surrounds and rear surrounds, too, might even consider moving the couch forward a bit? 5ch may work better in that room, too.

 

[zainframe]

Welcome to the forum. That is a very nice setup and well arranged room. Love the Lego behind the couch.

IMO, you're forcing 7.x.x in a room suited to 5.x.x. The rear surround are meant to be 5-7 ft. behind the listening position and 3-5 ft. above ear height. (I feel the side speakers are low too, but, they don't bother you, so, back to the rears.)

You're sure there's discrete 7.1 and not some matrix processing mode engaged?

Does the front/rear confusion happen even if the rears are disconnected?

Have you tried turning the rear surround trims way down (almost to the point of being inaudible) and then turning them up slowly? In effect, you'll be taking them out of the mix and slowly bring them back in without overwhelming the front soundstage.

Hi,

Thanks for the suggestions!

As I mentioned - the farther the seating position is to the rear speakers (the more I move it towards the middle of the room), the worst the effect will be (as in the audio from rear speakers will sound more like it is coming from the front)- originally the sofa was almost in the middle of the room (6-7 feet away from the rears) and the side surround is slightly more forward- moving the the sofa nearer to the rear surround seems to lessen the issue. For this setup I had to move the front speakers and TV about 2.5feet forward because the fronts and TV were too far from the seating position. This is never my preferred room configuration - before this it was more aesthetically pleasing with the sofa located between 3/4-middle of the room and surround speakers higher with fronts and TV nearer to the front wall but so far this config gets me the best sound with the rears sounding more like 'rear' and better bass (bass is another whole long discussion but I think I am at a place where I'm happy with the current bass/sub sound).

For the low hanging surround speakers - they were 1-1.5 feet higher for a few years until a few months ago I re-arranged them to be more at ear level height, this helped the rear sound issue and also better separates the rears and corner ceiling (Atmos) speakers. In the 4th picture you can see the cable casing in the shape of '7' on the wall at the left rear speakers - the top tip of the '7' was the original location/height of the rear speakers (the side and rear surrounds are always at the same height with each other).

I am 100% positive the sources are discrete 7.1 - test source includes white noise generated by the amp level calibration tool. This issue is more prominent while playing games as positional audio becomes more important- with the old setup (higher rear speakers and sofa closer to the middle), any sound coming from behind (e.g. voices, gunshots etc) will sound either they are coming from the front speakers or some omni directional 'god voice' (cannot pinpoint the origin)- now it is better but still not 100% solved.

Have played with the rear speaker trims - and yes, they cannot exceed a certain volume, if they are too loud it will sound more like it is originating from the front.

BTW I do not think it is the TV bouncing off unwanted sound waves as I have experimented by covering it with a thick blanket. I have also covered the right wall with drapes to make it 'even' with the left wall which has a door covered with thick curtains. The 7 foot shelf at the rear left is new and does not seem to noticeably effect the sound.

Thanks again everyone!

 

[agarwalro]

The answer to your issue could be a projector screen with acoustical panels behind it .

What mounts are you using for the side speakers? They look very flush with the wall.

 

[zainframe]

The answer to your issue could be a projector screen with acoustical panels behind it .

What mounts are you using for the side speakers? They look very flush with the wall.

Projector? Though of that but the room is only 20feet long and TV technology is always ahead (especially when cost is considered) - A few years ago when I wanted to move to 1080p, FHD projectors were waaaay to expensive as compared to a 70inch TV. Now, 4k projectors are relatively more affordable but not ones with Dolby Vision or good HDR10. Anyway as mentioned, I doubt the TV is the culprit here.

Acoustic panels behind the screen? checked, very checked - as you can see in the previous pictures- the front wall is full of bass traps and acoustic paneling - the windows are covered with acoustic absorber boards and thick curtains. There are also 2 units of 2inch thick acoustic panels behind the TV - these were put mainly to manage the bass (which works, bass is much better now) and to reduce reflections when I moved the speakers 2.5 feet forward a few month back to compensate for the sofa being moved nearer to the back wall.

As for the mounts, I am using the built in wall mounts that comes with the RTiA1 and A3. The speakers were recently purchased at a very cheap price from a friend. Before this I was using 4 units or Polk Monitor 30 speakers (in the attached picture) for the rear and side surrounds, they are now used for corner ceiling speakers for Atmos.

As mentioned the nearer the listening position is to the rear speakers, the less the 'front sounding' effect so at one point I used the mounts in the attached pictures for the monitor 30s. Very ugly yes, but it did lessen the issue. Now they are unecessary because the RTiA3 are much 'longer' and also too heavy for the mounts to support.

Anyway guys, a little update - I had the idea of playing some music on my cell phone and put them on top of the rear speakers - result is: yeah same effect, there's a confusion on whether the music is coming from the rears or front. I also sticked it to the door on the far rear right to see whether pushing the angle outwards would solve the issue - NOPE, same thing. And as I move forward closer to the room center the effect is worst. Something is just not 'right' with the room acoustics , or I am not setting things right (or cannot due to the room limitations).

Thanks!!

 

[MrBoat]

That large, leather sofa, is not helping. That's basically a knee wall in that room. Unless there is frequently 3 people in there, two cloth upholstered recliners with some space between would be better IMO.

 

[zainframe]

That large, leather sofa, is not helping. That's basically a knee wall in that room. Unless there is frequently 3 people in there, two cloth upholstered recliners with some space between would be better IMO.

MrBoat,

Thanks for the suggestion - may I know why the large leather sofa is not helping? Is it the material? What bad effect would it cause?

cheers!

 

[agarwalro]

I missed the "didn't" in the paragraph and understood that your TV was causing too much reflection. Ignore my previous post. Sorry about that.

 

[agarwalro]

I still don't understand what happens with your front soundstage if the rear speakers are completely mute.

To be clear, if you play stereo tracks in 2.0 or 2.2 mode, there is no issue? The front soundstage is firmly in the front.

The problem only manifests when you're playing 5.1 to 7.1.4 tracks and the rear speakers are sounding.

 

[TLS Guy]

I'm not sure what your problem is. However I can give you some general principles. First a few questions. Does this happen on all 7.1 discs?

Do you have a BD of War Horse? I say this as that movie is very well mixed. It gives by far the best 360 degree localization of any production I know of. If you can not get good 360 degree localization with that disc there is something wrong.

Does you Onkyo receiver have a auto speaker distance setting? This is important as the measured distance is far from always correct due to speaker time shifts. Does it have auto level setting?

Now an important point is that we localize by first time arrival and intensity, or loudness if you will.

Reflections are usually delayed and multiple and of delayed intensity and helpful. Occasionally you run into the odd very dominant first reflection that can cause trouble. In addition some speakers have an off axis response very different from the axis response this can cause significant problems.

One of the hall marks of good speakers is good on and off axis response.

I see nothing about your room to make me suspect an over dominant first reflection problem.

To localize sounds between speakers, in other words to get a good 360 sound field, all speakers need to have a good on and off axis response, play at the correct volume, and have correct arrival time at the listener. It also requires that the recording master be competently engineered so that speakers are set to play at the correct relative intensity to localize sounds between speakers.

If this happens then the illusion will occur, if not it won't.

So you need to make sure the speakers are set to the correct distance by electronic means and not tape measure, and that the relative intensity of each speaker is also set by an auto cal program. I have a suspicion that the Denon you talk about will be more competent in these matters than your Onkyo.

I do have a concern that you have Polk speakers. To me these always sound awash in time aberrations and other problems. To be honest they are well to the top of my avoid list. So my hunch is that they likely are an issue.

If all the things I have mentioned are carries out correctly and you still have the issue then I suspect it is the "Pig in a Polk."

 

[zainframe]

I still don't understand what happens with your front soundstage if the rear speakers are completely mute.

To be clear, if you play stereo tracks in 2.0 or 2.2 mode, there is no issue? The front soundstage is firmly in the front.

The problem only manifests when you're playing 5.1 to 7.1.4 tracks and the rear speakers are sounding.

Stereo tracks are ok, front speakers are ok - localization and imaging for the front speakers are ok on both stereo the and surround modes.

As mentioned in my previous postings - yesterday I tried playing some music on my cellphone and put it on top of my rears speakers - it was hard to pinpoint the source of the sound - it does prominently sound like its coming from the rear but I can hear a hint of 'sound' coming from the front at the front speaker area (if cell phone is on left rear speaker, there is a hint of sound as if coming from the left speaker and same for the right).

Thanks!

 

[zainframe]

Hi TLS guys,

Thank you for helping. I will try to answer my best (in blue).

I'm not sure what your problem is. However I can give you some general principles. First a few questions. Does this happen on all 7.1 discs?

Yes it happens on 7.1 discs. Also when testing white noise using the amp calibration tool, and worst on games that supports 7.1 natively where positional audio is really important .

Do you have a BD of War Horse? I say this as that movie is very well mixed. It gives by far the best 360 degree localization of any production I know of. If you can not get good 360 degree localization with that disc there is something wrong.

I will get War Horse, I hope its a good movie

Does you Onkyo receiver have a auto speaker distance setting? This is important as the measured distance is far from always correct due to speaker time shifts. Does it have auto level setting?

I have tried various ways of configuration, auto settings and also tweaking the settings by manual measurements - no difference.

Now an important point is that we localize by first time arrival and intensity, or loudness if you will.

Reflections are usually delayed and multiple and of delayed intensity and helpful. Occasionally you run into the odd very dominant first reflection that can cause trouble. In addition some speakers have an off axis response very different from the axis response this can cause significant problems.

One of the hall marks of good speakers is good on and off axis response.

I see nothing about your room to make me suspect an over dominant first reflection problem.

I am by no means an expert but neither can I!. In fact I'm a bit worried that the room is over treated and may turn into an anechoic chamber .

To localize sounds between speakers, in other words to get a good 360 sound field, all speakers need to have a good on and off axis response, play at the correct volume, and have correct arrival time at the listener. It also requires that the recording master be competently engineered so that speakers are set to play at the correct relative intensity to localize sounds between speakers.

If this happens then the illusion will occur, if not it won't.

So you need to make sure the speakers are set to the correct distance by electronic means and not tape measure, and that the relative intensity of each speaker is also set by an auto cal program. I have a suspicion that the Denon you talk about will be more competent in these matters than your Onkyo.

Base on my very amateur testing - it seems that the speaker may not be the issue- tested various speakers for the rear surrond, also positions, direction of speakers, level, distance etc. And yes apart for the need of 11 channels and Dolby Vision pass through, the reason I am going Denon is that Onkyo AccuEQ auto calibration does not work well in my setup (I cannot get good results no matter what I try) and I disable the autoEQ settings. I am hoping the Audessey in Denon would fare better.

I do have a concern that you have Polk speakers. To me these always sound awash in time aberrations and other problems. To be honest they are well to the top of my avoid list. So my hunch is that they likely are an issue.

I have borrowed/loaned a few speakers to test, one of them is a pair of PSB bipoles in the attached picture - same results .

If all the things I have mentioned are carries out correctly and you still have the issue then I suspect it is the "Pig in a Polk.

As mentioned in my previous posts, I strongly suspect that this is not a speaker issue or the settings on the receiver but more of a room, positioning issue. The attached diagram explains what I am experiencing - moving the head slightly will make the listener pinpoint the rear surround sound.

Thanks again! You guys are very helpful!

 

[yepimonfire]

That’s bizarre.

A quick primer on how we localize sounds:
Inter aural time differences (mostly for lower frequencies), and inter-aural level differences (for higher frequencies) help us determine horizontal left to right sound location, this works from about 0 degrees to around 90 degrees. When a sound is either behind us, or above/below us, pinna filtering alters the frequency’s that reach our ears, for example, we can interpret a sound as coming from above us because our pinna creates a boost at 7khz, and a deep notch at 12khz. I don’t remember off the top of my head what response curve modifications happen for sounds behind you, but you are likely not experiencing “cone of confusion” effects, as this would simply skew a left to right balance.

My guess is that a first reflection point for the rear speakers is bouncing the full range sound back to your ears from the front, ruining the localization based on HRTF and pinna filtering. While this is generally a good thing, the majority of Polk speakers I’ve owned have fairly wide dispersion, so a good deal of high frequency content would be contained in the early reflections.

What is the distance of the center line from the rear speakers to the mlp, distance to the side wall, height of the tweeter from the floor/ceiling, ear level height, and distance to the back wall? I can tell you what areas need to be treated based on this.

Btw, very nice setup you have there! I’m a big Polk fan, and have always wanted to own those bigger RTi speakers you’ve got up front. How is the low end from them? The big bass drivers in the towers always looked like they could dish out some serious bass with good authority.


Sent from my iPhone using Tapatalk

 

[zainframe]

That’s bizarre.

A quick primer on how we localize sounds:
Inter aural time differences (mostly for lower frequencies), and inter-aural level differences (for higher frequencies) help us determine horizontal left to right sound location, this works from about 0 degrees to around 90 degrees. When a sound is either behind us, or above/below us, pinna filtering alters the frequency’s that reach our ears, for example, we can interpret a sound as coming from above us because our pinna creates a boost at 7khz, and a deep notch at 12khz. I don’t remember off the top of my head what response curve modifications happen for sounds behind you, but you are likely not experiencing “cone of confusion” effects, as this would simply skew a left to right balance.

My guess is that a first reflection point for the rear speakers is bouncing the full range sound back to your ears from the front, ruining the localization based on HRTF and pinna filtering. While this is generally a good thing, the majority of Polk speakers I’ve owned have fairly wide dispersion, so a good deal of high frequency content would be contained in the early reflections.

What is the distance of the center line from the rear speakers to the mlp, distance to the side wall, height of the tweeter from the floor/ceiling, ear level height, and distance to the back wall? I can tell you what areas need to be treated based on this.

Btw, very nice setup you have there! I’m a big Polk fan, and have always wanted to own those bigger RTi speakers you’ve got up front. How is the low end from them? The big bass drivers in the towers always looked like they could dish out some serious bass with good authority.


Sent from my iPhone using Tapatalk

Hi Yepimonfire,

The floorstanding RTiA7 bass is great for music! Cant comment much on movies as I only use the full range for stereo music - For movies/surround I set the crossover to 80Hz and let the dual SVS PB-1000 do the 'low end' job.

I've attached the measurements for the rear speakers as you requested (maybe they are a few inches off here and there). Hope you can help shed some light on this issue. Mind you I've tried almost all kinds of positioning (higher, lower, outwards, inwards )and the pointing of the speaker drivers (up, down, left, right) EXCEPT for pushing them way outwards towards the side walls because of the door position. I've also tried different speakers (Polk Monitor 30 and PSB bipoles) without much success and the amateur testing I did with cellphone music (I explained it a few posts before) seems to show that this issue may not be speaker related.

I may not 100% understand your localize sound primer but it sounds to me like this may be able to be solved by EQ or some audio calibration?

Thank you so much!

 

[yepimonfire]

Hi Yepimonfire,

The floorstanding RTiA7 bass is great for music! Cant comment much on movies as I only use the full range for stereo music - For movies/surround I set the crossover to 80Hz and let the dual SVS PB-1000 do the 'low end' job.

I've attached the measurements for the rear speakers as you requested (maybe they are a few inches off here and there). Hope you can help shed some light on this issue. Mind you I've tried almost all kinds of positioning (higher, lower, outwards, inwards )and the pointing of the speaker drivers (up, down, left, right) EXCEPT for pushing them way outwards towards the side walls because of the door position. I've also tried different speakers (Polk Monitor 30 and PSB bipoles) without much success and the amateur testing I did with cellphone music (I explained it a few posts before) seems to show that this issue may not be speaker related.

I may not 100% understand your localize sound primer but it sounds to me like this may be able to be solved by EQ or some audio calibration?

Thank you so much!View attachment 22647

How far to the front wall is the mlp?

Distance from the speakers to the back wall?


Sent from my iPhone using Tapatalk

 

[yepimonfire]

One more thing as well, what’s the baffle width of the speaker?


Sent from my iPhone using Tapatalk

 

[agarwalro]

Have you tried replacing the ceiling diffuser with absorbing panels?

 

[zainframe]

Have you tried replacing the ceiling diffuser with absorbing panels?

No, I have not - maybe I'll try taping some drapes/blankets next weekend. Worth a try.

Thanks!

 

[zainframe]

One more thing as well, what’s the baffle width of the speaker?


Sent from my iPhone using Tapatalk

Hi,

The RTiA3 dimensions are 14.75x8.44 inch. I've also attached some measurements of the room - hope you can read my handwriting .

Cheers!