You need a minimum of 4 feet and 8 feet is a lot better between the listener and any walls. After about 8 feet it really does not matter that much (diminishing returns).
If you cannot get at least 4 feet between you and the wall behind your head then you can reduce the problematic reflections by putting up some RPG skylines or heavy curtains.
Do not under estimate how bad teh wall behind your head can sound. It can ruin the bass and it will totally ruin imaging and soundstage - the sound will be claustrophobic and fatiguing. Those who cannot hear the deleterious effects of walls near the listening position should seriously consider whether it is even worth investing in high end gear.
You need to treat the wall behind your listening position. I have used ASC products for this with excellent results.
It's best to have the listner away from the back wall as Shadorne mentions. But if you cant then putting the listener right against a treated back wall can be a very close 2nd best. When right up against the wall the reflections are not delayed enough to cause blurring.
I use GIK products for treating the wall directly behind me (aka the back wall).
Yup, the front wall is behind the speakers; the rear wall is behind the listener. It's the front and the rear of the ROOM.
"But if you cant then putting the listener right against a treated back wall can be a very close 2nd best."
What is second best?
I use treatments behind me and I have no issue with reflection.
I prefer to sit close to the wall behind me, so long as that wall is properly treated.
My speakers are 40" (about a meter) from the wall behind them (Magnepans, needing the space) and i sit in the middle of the room.
The walking space to the rest of the apt is behind my listening chair. So the chair is out into the room from small divider behind it about 7ft (two meters) and the wall falls back away both sides of the 4 ft wide (one meter) divider.
It is difficult to be right up against the wall behind your head for good sound.
I see a lot of the posts mention its not good to have your head near to back wall. But the method I've recently started to use (to good effect so far) recommends to do this ( with minor to no room treatments )
Its the method recommended by Immedia/Sonics explained here:http://www.immediasound.com/Speaker%20set-up%202009.pdf
Any thought as to its merits?
Thanks for your comments! Well I just read the article suggested by Pcoombs and goes against the comments above given! In this paper it is suggested that the lisener chair be located against the rear wall!! Can someone explain who is right?
Welcome to the subjective(but fascinating) worid of High End audio. there`s a modicum of "right" or absolute answers, i.e. tube or solid state, digital or analog, silver or copper etc. If possible try moving you listening position and compare the differences, it`s the only way.
Best of Luck,
Tiofelon, yes try and give the method I linked to a try . What led me to give it a go was the idea that it works well in rooms that do not have any or much room treatments. My system, like many others I expect. Is not in a dedicated listening room but in my living room and both my wife and I agree that the large diffusers and absorbers etc wouldn't be acceptable( plus the expense!)
But what is possible, with my speakers at least, was to install some Herbie teflon gliders and when needed( critical listening) to pull the speakers into the middle of room. At other times they stay closer to back wall.
Here's another link to a review of method.http://www.soundstage.com/audiohell/audiohell20011
The Audio Physics method (Immediasound) has worked extremely well for me when I used it in smallish rooms. Having the chair within a foot or so, or even against the untreated rear wall was not a problem. It also allowed me to pull the speakers further into the room. I find the method works best with long wall placement of the speakers, which is my preference anyway. However, I suppose that's another bone to pick as most people I know prefer short wall placement.
I too prefer long wall placement.
The simple explanation is that
1) Bass response is always the worst close to a wall - just try it by walking around the room - you always get a more uneven bass response when you sit near a wall.
2) The secondary reflections will collapse the soundstage to the speakers - just try it by moving your position out into the room and you will find the soundstage grows in height and width and frees itself from the speakers. However, with the back of your head against a wall the sound collapses to the speakers.
Depending on your setup this will be more or less apparent. You need to have the speakers free from nearby reflections to begin with to hear 2.
The problem with Sonics explanation above is this statement:-
"Secondly, the reflections are shorter than the circumference of the head, so the brain cannot measure the time delay between the ears, and therefore cannot localize the source of sound. When the brain cannot localize reflections it ignores them."
This is obviously not true for a listener seated at 1 to 3 feet from the wall behind them, as suggested in the article). Physically the reflected sound has to travel at least two feet further than the direct sound when the listener is 1 foot from the wall. As the article mentions at the beginning, this is very bad because of the 5 msec rule which requires that NO reflections reach the ear prior to 5 msec.
If you apply the 5 Msec rule(which is scientifically proven) then you need a minimum 4 feet from the speakers to the side walls and at least 4 feet distance between you and the rear wall behind your head (as I recommended).
Why do I say 4 feet and not 5 feet (since 5 feet is about 5 msec)?
This is because the diagonal path that reflected sound follows will almost always be longer than the physical distance because the sound has to "reflect". You can, in some situations, get away with 3 feet.
The inconsistencies in the article by Joachim Gerhard should be self evident - although a lot of what he says about speaker placement is valid. Although, such a wide speaker separation tends to exaggerate the stereo effect often to the detriment of a more natural presentation in favor of a more impressive presentation.
IME, with speakers out from nearby walls (especially sidewalls) and absorbing room treatment behind the close wall to the listener, I enjoy better sound than from other arrangements.
One has to work with the room he/she has. If it allows for enough space behind the speakers, behind the listener and to the sidewalls, that is great. If it does not, one needs to adjust. Jim Smith just voiced my system in my small to medium sized room. The first thing he did was to locate the listening seat for best and smoothest bass response. In my case, this meant moving the sofa even closer to the rear wall. My ears are now about 12" from the wall behind my head, but that wall is treated with absorption. Bass response, both in extension and smoothness, as well as soundstaging and image focus all improved with deliberate and careful placement of the speakers, the listening seat and specific room treatment.
I think it is very hard to generalize about this stuff. One does want to minimize reflections and give most speaker designs space to breath, but beyond that, each room is different and each system is different, and it will take time and experimentation with placement to optimize the sound in a given room for the most realistic presentation.
I think it is very hard to generalize about this stuff.
If everyone accepts that speakers are best kept away from reflective surfaces by several feet (ideally 3 or 4 feet or more in order to get an optimal stereo image and soundstage) then according to physics it is a given that the same applies to the listener. (A reflected sound within 5 msec of that of the direct signal from speaker to listener can be created either way: Speaker=>near speaker side Wall=>listener or Speaker=>near listener rear wall=> listener; and in both cases the imaging will not be as precise as without these close reflections)
Shadorne, I doubt anyone is disagreeing with what you've posted. I think that the use of specific absorbing room treatment can go a long way in adapting to the situation.
I disagree with your conclusions completely.
As do many others, including the late John Dunlavy.
BE FREE FELLOW FREQUENCY FREAKS: It's personal...My speakers are on either side of a "fake" fireplace about a foot and a half from the back wall and 6 inches from the "fireplace" walls..with a powered sub stuck in behind the left speaker. The sweet spot is on a couch 3 feet from the back wall (to enjoy that along with me you need to sit in my lap or on my shoulders...creepy but true). Done. I used to move the speakers into the room for "serious" listening but stopped because they sound GREAT where they are...go figure. Floor rug, other comfy chairs...sloping high ceiling...and since I'm a pro musician/sound technician (live shows mostly), my ego would never allow me to pay attention to so-called "formulas" for speaker placement any more than I would entertain suggestions on how much to salt my food or sweeten my coffee. I actually like the "tone" of my room and listen to a very wide range of music...and it all sounds different, very different, and my system puts a stable soundstage right in front of me. Did you know that sound level CHANGES percieved frequencies due to comb filtering and phase anomalies? So unless you listen to everything at exactly the same level your room treatments might be futile unless you live in an empty concrete box. And do you know what a "dead" room sounds like? I do...it sounds terrible (unnatural). Hense the word "dead". Here's another one: I replaced my speaker spikes with Vibrapods for a large improvement in everything (my hair even got thicker)...and from what I've recently read you can see THAT tweek train coming with suspended speakers (new Sonus for example) being the New Black. Who knew?
The front wall is the wall thats in front of you when your in the sweet spot . I thought Stereophile put that matter to rest years ago .
I think that the use of specific absorbing room treatment can go a long way in adapting to the situation.
I have seen research that suggests you need to get the reflections 21 db below the primary signal to make them inaudible (according to lab tests rather than theory).
Diffusion behind the listener might be the most effective. If the listening position is anywhere near a corner then corner bass traps would also help.
It depends on the size of the room too. In my small room the listening position from the rear wall is about 2 feet(Tiofelon -I think we need to get the front/rear wall description right in the first place).
Personally I guess folks can either choose to place the listening chair at # feet from the rear wall or against it to achieve the best results that suit his room/ears/listening preference. Nevertheless, I believe it is still prudent to have some space from the rear wall to the listening chair for optimum results IMO. Shadorne's 4 feet - 8 feet can be useful in large spaces but not feasible for smaller rooms. It is more important to treat the wall behind the listener with absorption or diffusion(personally I prefer diffusion).
To summarize, try different configurations and adopt the one that sounds the best to your ears. Speaker placement and listening distance relative to wall boundaries are all correlated.
The obvious solution to the dilemma of "room treatment" is to buy a good set of headphones.