Stereo image / centering issue in a acoustically treated room

[john_k_antony]

Experts,

I recently finished setting up my dedicated HT room and Listening room with basic acoustic treatments. I got very good results with the acoustic treatment regarding clear vocals, flat frequency response and controlled bass. I got my bass shy speakers (KEF iQ7) to sound with much better bass and found that my speakers got a new "life".

Now I noticed an annoying niggle. After listening to the setup for a while, I kind of feel that the sound stage is shifted or exaggerated towards left side. I feel the sound stage is wider on left compared to the right. I quickly checked with my wife and she also felt that when we sit in the center of the room, the sound stage is slightly shifted to the left.

Now I tried the following

1. Moved the speaker closer/away from the wall. Both the side walls have sound absorbers.
2. Toe in of the speakers with different angle.
3. Increased the sound level of the right channel.

Even with all that, I still feel that the sound stage is wide on the left compared to the right side. I also felt that for some instruments or notes, the difference is quite significant.

I am now going to do some more experiments to see what is the root cause of the issue. I want to know what from the following is causing the issue.

1. Source / CDP
2. AMP
3. Speakers
4. Room

I will try swapping the left and right channel and see if the sound stage shifts to other side. It it does, then its my equipment. Now if it doesn't, then its the room playing the spoil sport. Then I will have a difficult problem to deal with.

I would really appreciate if you guys could comment on this problem I am facing!.

Here is how the speakers are setup. I know its not ideal setup though.

1. Room size - 24x15.6.
2. Speakers are placed along the 15.6 wide wall.
3. Speakers are 3' away from rear wall and 1.5' away from side wall.
4. Speakers are toed in towards the primary listening position.
5. Speakers are kept 12' apart.
6. Primary listening position is 16' away from each speaker.

I also feel that the sound stage is very sensitive to the listening position. When I move to the next sofa either to the right or left of the primary listening position, there is a noticeable shift in the stereo imaging / centering.

Thanks,
John.

 

[ranjeetrain]

Need not necessarily be speakers. Check all cables/interconnects. Remove, see if there is any carbon deposit, connect again making double sure all contacts are clear and firm.

Your speakers seem to be quite directional. Get rid of the toe in. Start from keeping them flat out. What do you hear? What do you lack? You don't necessarily need to toe in the speakers. Toe in if the focus is not correct (such as voices are scattered).

You also may have too much of absorption. If nothing else helps, remove all absorbers and start by inserting from reflection points.

 

[hydra]

Also do check the distance from the baffle of the LHS speaker and the RHS speaker to the center of the backrest of the listening chair.

I had a similar issue when I set up my speakers right after I got them: The center image was always a bit to the left. I first thought it was a level imbalance issue between the channels in my amp. I tired swapping channels by switching the speaker wires behind the amp, but the issue remained. After a bit of trying different things, I figured out that the left speaker was closer to the center of the backrest of the listening chair by 3 inches. I pulled the speaker closer to the rear wall by that much, and the center image locked into the middle of the space between the speakers.

 

[Thad E Ginathom]

To be sure, you need to test with test tones, not music. I'm sure you can download what you need (maybe here?).

Do this with both you and your wife, and maybe get anther volunteer too, to rule out ears being part of the problem.

 

[ghatgepatil]

Try using a bit of the 'cardas' method of speaker placement.

I am using 'a bit of ...'. As the full method might mess with the room aesthetics. Yes, remove the stiff toe-in. Give a slight 5 deg tilt max. Full up the speakers by a foot from the front wall to make it 4'. Similarly, keep 3' distance each from the side walls. That makes the speakers at @ 9-9.5' from each other. You could reduce this distance to 8' from the 9-9.5' depending on your listening results.

 

[Shivam]

Check your system first by switching left and right channels as you have planned. Use a mono recording or test tones.

 

[haisaikat]

are the cable lengths same from speaker to amp? Also does your room has windows or other absorbing obkects on right that you do not have on the left?

 

[john_k_antony]

Thank you very much guys for the super fast responses. I will try all the experiments now. I have made all the abosorbers removable and changeable. I will start with that.

Thad, even I was wondering that my ears might be the culprit. That's why I asked my wife to check . Even my dad said he could feel the shift in the image. BTW, thank you very much for different pink tones. I was using the pink tone from my BDP to test. I will try with the ones provided in the link.

Hydra, I am really surprised to know that 3" error in placement can cause the image to shift!. Did you use any measurements to confirm the imaging got fixed or you just trusted your ears?

Thanks,
John.

 

[Thad E Ginathom]

A big difference from a small speaker placement change would not surprise me, but, although the theory says to make them equal and only as long as they need to be, I would have thought that it would take many metres of speaker-cable length difference to result in a noticeable balance change.

Isn't it a pity we can't see sound!

 

[john_k_antony]

A big difference from a small speaker placement change would not surprise me, but, although the theory says to make them equal and only as long as they need to be, I would have thought that it would take many metres of speaker-cable length difference to result in a noticeable balance change.

Isn't it a pity we can't see sound!

Rightly explained Thad. I too wish we could see sound waves .

My speaker cables are good quality ones made by Mr Murthy in Bangalore and they are just 3 meter long

 

[hydra]

...
Hydra, I am really surprised to know that 3" error in placement can cause the image to shift!. Did you use any measurements to confirm the imaging got fixed or you just trusted your ears?
...

I was quite surprised myself then. But yes, the difference was clearly perceivable. I'm blessed with better than average imaging in my room, and we can actually "see" the center image shifting. In this case, it shifted about 1 to 1.5 feet to the right, to the center. It probably has to do with the loudness level of the individual channel going up/down because of the difference in distance from the ears/chair.

I sit fairly close to the speakers (about 7 feet away from the baffles), so I'm not sure if that causes the differences to be more easily felt.

I didn't do any measurements. I played it by ear.

You can also see how different it can be. Just pull your RHS speaker closer to you by about 3 or 4 inches (OR push the LHS speaker away from you by the same). Regardless of what the issue is now (that causes the image to shift to the left), the image WILL shift to the right, towards the center.

 

[hydra]

^^ Manoj, I do get the tone of your question.

What happens when the head shifts does not matter to me. What matters to me is that I start out with things set up right -- they way they should be, with the image centered (in this context). After that, I sit in my listening chair and listen to music in a way that I'm comfortable, and I don't let the center image or anything else decide the way I sit and enjoy my music.

 

[manoj.p]

Hydra,

There is no tone. If 3" can make that big difference, then it means the speakers have a tiny tiny sweet spot.

 

[hydra]

Manoj, that could be the case.

John, you might have tried this out, but just in case you haven't: Did you check if the RHS speaker is connected with the + and - wires in the + and - terminals itself? Do check at the amp side too.

 

[john_k_antony]

Hydra,

Thanks for the tips. The speaker polarity is fine.

I want to try out the room response using the free REW (REW - Room EQ Wizard Room Acoustics Software) software. I am too tired to check it out today. Will try it tomorrow if I get some time.

BTW, I also started noticing the same issue slightly with my HT speakers as well. So its the room that is playing the spoil sport. I am really confused as I have done exactly same treatment to the both sides of the wall and the ceiling and floor.

-John.

 

[darshanjoshi]

You tried swapping Channels on AVR or did you tried swapping speakers ?
By swapping speakers you will understand whether speakers is a problem.

One of my friend had a similar issue and problem was crossover of the speaker. He replaced the crossover and problem got solved.

 

[john_k_antony]

You tried swapping Channels on AVR or did you tried swapping speakers ?
By swapping speakers you will understand whether speakers is a problem.

One of my friend had a similar issue and problem was crossover of the speaker. He replaced the crossover and problem got solved.

I don't think its the speakers as the same issue is there with my home theater speakers as well.

But. I will try swapping the speakers though.

Thanks,
John.

 

[Deleted member 45006]

I don't think its the speakers as the same issue is there with my home theater speakers as well.

But. I will try swapping the speakers though.

Thanks,
John.

Your room's left half is 100% complementary to the right?( My question may be too stupid, since I can see you are not a novice with acoustics!) but then again, I had a similar issue where my left was having some frequencies boosted especially vocals were on the higher side... My thing was simple my right speaker was having more space as my door was near it,I added more absorbing cushions to the left wall and it helped..

 

[murali]

Experts,

I recently finished setting up my dedicated HT room and Listening room with basic acoustic treatments. I got very good results with the acoustic treatment regarding clear vocals, flat frequency response and controlled bass. I got my bass shy speakers (KEF iQ7) to sound with much better bass and found that my speakers got a new "life".

Now I noticed an annoying niggle. After listening to the setup for a while, I kind of feel that the sound stage is shifted or exaggerated towards left side. I feel the sound stage is wider on left compared to the right. I quickly checked with my wife and she also felt that when we sit in the center of the room, the sound stage is slightly shifted to the left.

Now I tried the following

1. Moved the speaker closer/away from the wall. Both the side walls have sound absorbers.
2. Toe in of the speakers with different angle.
3. Increased the sound level of the right channel.

Even with all that, I still feel that the sound stage is wide on the left compared to the right side. I also felt that for some instruments or notes, the difference is quite significant.

I am now going to do some more experiments to see what is the root cause of the issue. I want to know what from the following is causing the issue.

1. Source / CDP
2. AMP
3. Speakers
4. Room

I will try swapping the left and right channel and see if the sound stage shifts to other side. It it does, then its my equipment. Now if it doesn't, then its the room playing the spoil sport. Then I will have a difficult problem to deal with.

I would really appreciate if you guys could comment on this problem I am facing!.

Here is how the speakers are setup. I know its not ideal setup though.

1. Room size - 24x15.6.
2. Speakers are placed along the 15.6 wide wall.
3. Speakers are 3' away from rear wall and 1.5' away from side wall.
4. Speakers are toed in towards the primary listening position.
5. Speakers are kept 12' apart.
6. Primary listening position is 16' away from each speaker.

I also feel that the sound stage is very sensitive to the listening position. When I move to the next sofa either to the right or left of the primary listening position, there is a noticeable shift in the stereo imaging / centering.

Thanks,
John.

Move your speakers closer, say, keep them 8 ft apart and sit within 8 - 10 ft from each speaker. If things improve, you can try to change the 8 ft a little bit but not beyond 9 ft. In home listening environments, speakers are never kept apart more than 9 ft and ideally 7 to 9 ft. The listening position is always 80 - 100% of that distance from each speaker.
I wonder what you are trying to achieve by dragging the speakers so much apart. With good speakers, the soundstage does not change beyond a certain distance and in fact, the more they are apart, the less will be the center focus. Toe-in is only for precise fine tuning and locking the center and never to get the center focus from dispersed pattern.

Trust this helps.
murali

 

[john_k_antony]

Your room's left half is 100% complementary to the right?( My question may be too stupid, since I can see you are not a novice with acoustics!) but then again, I had a similar issue where my left was having some frequencies boosted especially vocals were on the higher side... My thing was simple my right speaker was having more space as my door was near it,I added more absorbing cushions to the left wall and it helped..

Hi Alby,

I wouldn't say 100%. Because I have doors on both the left and right walls of the room and the door in the right side is 10 cm closer to the right speaker. Again both the doors are 10' away from the speaker baffle and I do have some absorbing panels on the doors as well. Also the width of the doors are slightly different. The door on the left wall is 6" wider than the door on the right side.

However, these doors come way behind the first and second reflection point. I measured the first and second reflection point using the regular mirror method. And I have same type of absorbing panels at both the refection points on the left and right side of the wall.

However, I will try to put some more absorbing materials on the doors and see if that is fixing the issue!

I must say guys.. getting acoustics right is VERY VERY tricky .

-John.