Speaker distance from side wall?

Y

yepimonfire

Audioholic Samurai
I’m trying to improve the imaging of my front l/r. Currently, I’m seated 10.5’ away, with the fronts 7.5” apart, ie a narrow 41 degrees. The width of the room is ~11.5’, if I placed my speakers in an equilateral triangle, like it’s supposed to be, that puts my speakers about 6” from the side wall.

My concern with this is the relative level/timing of early reflections. If my math is correct, this places the first lateral reflection 11” in front of the speaker at an angle of 27 degrees. Adding 30 degrees for toe in would make this 47 degrees. Since the distance from the speaker to the reflection is about 13”, the timing difference is just under 1ms.

Based on the directivity of my speakers, that should equate to an approximate 6dB drop in level at a 45 degree angle above 1khz (which, according to Toole, is the frequency range that matters regarding imaging distortions from reflections). Up to about 14khz the off axis sound hitting the wall should be spectrally similar to the on axis sound. Coloration of the sound is unlikely, I’m more worried about getting tight, focused imaging, avoiding the diffuse mess overpowering reflections might cause.

The reflection point will be treated with 2” Auralex panels, which have an NRC of 1 above 500hz. I have no idea how noise reduction coefficient translates to dB attenuation.

http://www.audioholics.com/room-acoustics/room-reflections-human-adaptation

Based on Tooles article, treating the reflections would not be a bad idea in my case.

Has anyone placed speakers close to a sidewall before and had good results? Bad results? Any suggestions?


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j_garcia

j_garcia

Audioholic Jedi
6" seems too close to me. Rather than treat immediately, I prefer to move that first reflection beyond the listening position, it tends to yield better results. I am not checking the math, but listening to it in a variety of angles and distances from the wall will tell you very quickly what is best.
 
TheWarrior

TheWarrior

Audioholic Ninja
Toe them in and move them around. Play a familiar loop of music and move seat to seat. Listen critically and let your ears decide when it sounds good, and not be concerned with how it 'looks'.

But I'd suggest re-reading Floyd's article if you think guessing at some randomly sized panel absorbers without taking comprehensive measurements, was recommended.
 
Y

yepimonfire

Audioholic Samurai
Toe them in and move them around. Play a familiar loop of music and move seat to seat. Listen critically and let your ears decide when it sounds good, and not be concerned with how it 'looks'.

But I'd suggest re-reading Floyd's article if you think guessing at some randomly sized panel absorbers without taking comprehensive measurements, was recommended.
I’ve taken measurements and listened very critically. The current treatment scheme I have set up both sounds and measures very nice.

One thing I noticed this morning when messing with toe in, the phantom center sounds much better with the speakers toed in to where they cross about a foot in front of me, any reason why a steep toe in like this would be a bad idea?


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Y

yepimonfire

Audioholic Samurai
6" seems too close to me. Rather than treat immediately, I prefer to move that first reflection beyond the listening position, it tends to yield better results. I am not checking the math, but listening to it in a variety of angles and distances from the wall will tell you very quickly what is best.
Move it beyond? How would one do that? Unless I’m misinterpreting what you’re saying, regardless of where the speakers are placed, the first reflection will always be in front of the mlp. Greater distances from the side wall increase the time delay and reduce the level of the reflections obviously. Considering how narrow my room is compared to the length, getting a better balance between direct sound and early reflections is pretty much impossible by placement alone, unless I want my speakers to be 3’ apart, which is why I have decided absorption is the best approach. My ears seem to agree :)


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TheWarrior

TheWarrior

Audioholic Ninja
I’ve taken measurements and listened very critically. The current treatment scheme I have set up both sounds and measures very nice.

One thing I noticed this morning when messing with toe in, the phantom center sounds much better with the speakers toed in to where they cross about a foot in front of me, any reason why a steep toe in like this would be a bad idea?


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"Phantom images rely on symmetry and the discipline of the listener to stay in the sweet spot." p157

"In rooms the precedence effect allows us to localize the presence of numerous reflections. It is a cognitive effect, occurring at a high level in the brain, meaning that it can be different at different times and places, for different sounds and changing experiences." Toole p154 Sound Reproduction 3rd edition.

Which also means that the more you absorb those reflections, the smaller the phantom image will be. Toole uses LEV and ASW (listener envelopment, apparent source width) to describe the effects of reflected sounds, but it is the precedence effect that allows us to localize sounds in the presence of numerous reflections. The placement of sources, ears, and even excessive absorption, can break down the precedence effect.

Personally, I've found Klipsch horns to sound better spread wide and heavily toed in. I don't recall exactly how much toe in, but crossing in front of the listener sounds about right. I would choose the arrangement that sounds better, regardless of how it looks!
 
KEW

KEW

Audioholic Overlord
One thing I noticed this morning when messing with toe in, the phantom center sounds much better with the speakers toed in to where they cross about a foot in front of me, any reason why a steep toe in like this would be a bad idea?
This paper by Bill Waslo discusses this with some good diagrams:
http://www.libinst.com/PublicArticles/Setup of WG Speakers.pdf

Here is a brief discussion of this paper:
http://www.chanemusiccinema.com/forum/archive/index.php/t-46879.html

One comment (by dguarnaccia) from the above Chane link:
Earl Geddes recommends that his Abbeys be crosses 2 feet in front of the main listening position. Roughly the same as the author suggests. The speakers are essentially toed in at 44 degrees. The imaging is amazing. I tried this with the sho10s and it was equally revealing. I suggest everyone try it.
I have a center speaker, but still find this beneficial for overall sound quality from the Klipsch RF-82ii's in my HT!
 
j_garcia

j_garcia

Audioholic Jedi
What I mean by beyond the listener is that first reflection based on the angle that it strikes the wall and hits your ears, if it is not also perfectly angled to hit your ears almost immediately, it will tend to sound better. As in, that reflection's angle would be off to the side from the listener (Toed in) so it either doesn't initially radiate off the wall or moved far enough away from the wall relative to the distance you sit away such that that reflection is in front or behind the listening position. That will depend on the speaker, and in the case of horns, as Warrior said, crossing ahead of the listener is where I'd probably start. I'd do treatments still, but a little adjustment of the angle, placement and treatments for your exact situation are always going to be required.

What I was really getting at is, your ears should tell you when it sounds right. That perfect imaging is pretty obvious when you hear it.
 
ATLAudio

ATLAudio

Senior Audioholic
This paper by Bill Waslo discusses this with some good diagrams:
http://www.libinst.com/PublicArticles/Setup of WG Speakers.pdf
Here is a brief discussion of this paper:
http://www.chanemusiccinema.com/forum/archive/index.php/t-46879.html
One comment (by dguarnaccia) from the above Chane link:
I have a center speaker, but still find this beneficial for overall sound quality from the Klipsch RF-82ii's in my HT!
"Personally, I've found Klipsch horns to sound better spread wide and heavily toed in. I don't recall exactly how much toe in, but crossing in front of the listener sounds about right. I would choose the arrangement that sounds better, regardless of how it looks!

Yep, good paper. Agreed. I've found that an equilateral triangle (this looks wider than it sounds.) with toe in at around 60 degrees works the best. My trig might be off but this has the speakers intersecting at my toes.

I've tried other placements that work too, but this has the least down side by a long margin. For one, lounging on the sofa with my head at one end, I still have a decent phantom center; not perfect, but still there.

I also feel that having my speakers about 2 feet out from the front wall helps best with I&SS around the front entertainment cabinet. YMMV
 
Dale Doback

Dale Doback

Junior Audioholic
I like mine as far away from the walls as sensibly possible (currently 3' from front wall & 4' to 5' from side walls). I've tried in the past to deaden the hell out of the front, so I could put speakers closer to the walls, but, didn't work lol (it did help though). I also don't like equipment or racks up front either. I am referring to music playback.
 
ATLAudio

ATLAudio

Senior Audioholic
I like mine as far away from the walls as sensibly possible (currently 3' from front wall & 4' to 5' from side walls). I've tried in the past to deaden the hell out of the front, so I could put speakers closer to the walls, but, didn't work lol (it did help though). I also don't like equipment or racks up front either. I am referring to music playback.
I used to be more inclined for maximum distance, but that all changed when I started actually using the Umik and REW to measure and find the best placement.
 
Y

yepimonfire

Audioholic Samurai
@TheWarrior What other suggestions besides absorption do you have? Before treatment, the room was too live, and the sound and imaging was a chaotic mess. Post treatment it sounds a whole lot better.

I don’t have any problems with “apparent source width” listening to music In 2ch in the sweet spot the speakers seems to disappear and project a soundstage that extends outside of them. The only issue I have is that the phantom center isn’t very tight. This problem is lessened post treatment, but still existing. One issue I have not addressed is the bare hardwood flooring. If I’ve discovered anything by messing with treatment placement, it’s that ceiling and floor bounce really muck up the soundstage. Not sure if getting a rug would help.


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Y

yepimonfire

Audioholic Samurai
I used to be more inclined for maximum distance, but that all changed when I started actually using the Umik and REW to measure and find the best placement.
Agreed. I had experimented with pulling the speakers about 4’ out from the front wall and gained nothing but lots of notches in the bass response. I settled on 2’ because in about 3 different rooms I’ve measured that seems to give the best response.


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William Lemmerhirt

William Lemmerhirt

Audioholic Overlord
How thick do you suppose?


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Just about anything would be an improvement. I guess I’d go for as thick as I could while not looking like Austin powers LR, lol.
 
TheWarrior

TheWarrior

Audioholic Ninja
@TheWarrior What other suggestions besides absorption do you have? Before treatment, the room was too live, and the sound and imaging was a chaotic mess. Post treatment it sounds a whole lot better.

I don’t have any problems with “apparent source width” listening to music In 2ch in the sweet spot the speakers seems to disappear and project a soundstage that extends outside of them. The only issue I have is that the phantom center isn’t very tight. This problem is lessened post treatment, but still existing. One issue I have not addressed is the bare hardwood flooring. If I’ve discovered anything by messing with treatment placement, it’s that ceiling and floor bounce really muck up the soundstage. Not sure if getting a rug would help.


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Without comprehensive acoustic measurements and understanding the layout and furnishings of a room, no suggestions can be made without guessing.

Floor bounce is a first reflection that is often recommended to be absorbed.

A rug by itself can tame very high frequencies, but a thick pad underneath makes it far more useful.

A phantom center can be created with surround movie tracks where the dialogue 'comes' from the display when L + R speakers and listener are properly positioned for stereo listening. Some, but not all movie soundtracks are mixed properly to allow for this effect to happen, and as quoted above, it varies greatly by the placement of listener's and speakers.
 
j_garcia

j_garcia

Audioholic Jedi
I found phantom center to be problematic at best. When dialog moves from one side to the other, it is very obvious and not always consistent. When it is "centered" playing from both speakers it is fine, but occasionally, it would be fully off to one side or the other and I didn't like that. Even adjusting width out further to the mains, it just didn't work to my liking and felt straight stereo worked better in some cases.
 
TheWarrior

TheWarrior

Audioholic Ninja
I found phantom center to be problematic at best. When dialog moves from one side to the other, it is very obvious and not always consistent. When it is "centered" playing from both speakers it is fine, but occasionally, it would be fully off to one side or the other and I didn't like that. Even adjusting width out further to the mains, it just didn't work to my liking and felt straight stereo worked better in some cases.
Listening to multichannel content without a center is obviously not ideal, much less even what was intended. A phantom center is simply a byproduct of psychoacoustics in how we as humans perceive sound vs. an linear microphone. Some content is mixed so you can get away without a center, but it'll never sound as good!
 

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