Speaker placement........

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Wayner

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Speaker placement........
« on: 7 Jul 2012, 07:10 pm »
I've been moving speakers around. I have found that small position changes can make big sound field changes. I generally like the speakers along the long wall, spaced as far apart as possible (without creating a void in the sound-stage) and keeping the toe-in angle as little as possible.

One rule I certainly have found is that each speaker seems to have it's own distance apart requirements and toe-in angle. Another rule is that too much toe-in makes for mono.

Wayner

Devil Doc

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Re: Speaker placement........
« Reply #1 on: 7 Jul 2012, 08:26 pm »
I agree with all of that but long wall placement. Never head anyone recommend that. Care to expand?

srb

Re: Speaker placement........
« Reply #2 on: 7 Jul 2012, 08:49 pm »
I think the majority of audio acousticians (a) prefer a rectangular room to a square room and (b) recommend speakers be placed on the short wall.

George Cardas, in his paper "Setting-Up Speakers In A Rectangular Room" (http://www.cardas.com/pdf/roomsetup.pdf) describes long wall placement starting with "If you are forced to place your speakers on the long side of a symmetrical, rectangular room ....."

Steve

jimdgoulding

Re: Speaker placement........
« Reply #3 on: 7 Jul 2012, 09:28 pm »
Short wall for me, too.  I should think bass will load to the room better in most cases and that it replicates most concert halls.  Now, that last bit may not matter much for studio made recordings but for ones made on location I believe it does.

Scottdazzle

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Re: Speaker placement........
« Reply #4 on: 7 Jul 2012, 09:48 pm »
The short wall has always worked better in my experience except when both walls are close to the same length and other factors are involved (doorways, arches, windows, etc.).

Listens2tubes

Re: Speaker placement........
« Reply #5 on: 7 Jul 2012, 11:25 pm »
I too use the short wall. Though if the room is big enough using the long wall gets you far from side wall reflections and can work quite well.

Wayner

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Re: Speaker placement........
« Reply #6 on: 8 Jul 2012, 12:28 pm »
OK, thanks for the responses.

Now I'd like to elaborate on why I like the long wall placement. First, music halls and I'm going to throw in cathedrals are long and narrow for a couple of reasons. First, it's easier for the audience to look forward rather then off to the side so this design is natural. Next, it does put most of the audience an acceptable listening position. Third, the long narrow construction of halls and cathedrals creates a large, natural reverberation which most people believe, enhances the music, giving it that "heavenly" sound.

Now if we put our speakers into that same configuration, a couple of things are going to happen. First, the distance between the speakers will be much closer then if we set up on the long wall. That means the equilateral triangle that George Cardas talks about is very small. If your speakers are 6 to 7 feet apart, then your listening position should be 6 to 7 feet from the speakers (at the intersecting radius from each).

Another problem with the short wall is exactly what happens in the concert hall or cathedral, that is many early reflections. So then people use wall treatments to reduce the natural reverberations now occurring in their living rooms. They are witnessing first, second, maybe third generation reflections and they are crossing the sound stage and destroying the stereo image as well.

Another problem with the short wall was addressed by Polk Audio with the SDA (stereo dimensional  array) system in which the left and right speakers were connected by a cord to introduce out of phase material to each speaker. What this did, was to reduce or cancel what is known as cross-talk distortion. It prevented the left ear from hearing the right speaker and the right ear from hearing the left speaker. I owned a pair of these speakers and you could close your eyes and point at a speakers perceived location, and then discover you were off by 10 feet.

The long wall offers natural cures to all of these problems. Because the speakers are further apart, the equilateral triangle is much larger and there usually is enough room for several people to witness the "sweet spot". Next, early wall reflections are taken out of the picture as most first reflections are going behind the listeners. To me, it is very important that the listener be well inside of the equilateral triangle to hear maximum stereo. And the spread of the speakers reduces or makes moot of the cross-talk distortion discussed earlier.

Wayner

rbbert

Re: Speaker placement........
« Reply #7 on: 8 Jul 2012, 01:27 pm »
For most, the big problem with long wall placement is the room size needed.  Assuming that your room dimensions are close to the Golden Ratio Cardas recommends (and BTW, the Cardas method is short wall placement), and that you want to place your speakers at least a little way into the room to avoid stimulating bass nodes, and that you place your listening position in from the rear wall to avoid comb filtering problems, you need your shortest room dimension to be about 18 ft with a 11-12 ft ceiling and a long dimension about 28 ft, and those are minimum dimensions

jimdgoulding

Re: Speaker placement........
« Reply #8 on: 8 Jul 2012, 02:34 pm »
Sitting inside of an equilateral triangle can be pretty amazing on some of my recordings.  On one in particular that is blumien miked the outside string sections from the photo on the cover move forward to more surround the listening position much like I imagine the conductor would likely hear.  This I can achieve with short wall placement.  Early reflection will depend upon how close the speaker is positioned to surrounding walls and the treatment, if any, of them.  I favor getting the speakers and my seat away from the walls and if your room is small and think this could shrink the soundstage, just move your seat to maintain an equilateral triangle and it won't, at least in my room it doesn't.  Closing my eyes reveals a larger space convincingly akin to the recorded space I can imagine than my actual room boundaries.  But, everybody knows that, right?

Wayner

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Re: Speaker placement........
« Reply #9 on: 8 Jul 2012, 05:09 pm »
Speaker positioning doesn't really follow any "Golden Rule" as Cardas might have everyone think. He didn't come up with anything, the Golden Rule of .6 to 1 to 1.6 has it's beginnings in biblical times.

The reality is the speakers performance within a room boundary. With so many designs, there just can't be any across the board rules on placement.

Every room has some kind of boundary restrictions or improbable seating arrangements, so as one might suspect, the "golden rule" is to experiment. I've learned long ago just cause some says its so, doesn't make it so.

I've spent days moving speakers around, spreading them apart, moving them together, changing the toe-in angle, adjusting tilt and at times I wondered if it would ever pay off. I know the sound I'm looking for and it's got to be here somewhere. Then one moment, it's payoff. Sound becomes 3D, bass is reinforced by the room in acceptable levels. Of course, the room affects bass nodes, take your speakers outside and listen to them there.

Anyway, I'm sure everyone has their own methods and their own favorite walls to place their speakers against. Sometimes placing speakers close to the rear wall is not a bad thing.

Wayner

Letitroll98

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Re: Speaker placement........
« Reply #10 on: 8 Jul 2012, 05:36 pm »
I agree Wayne, with the added caveat of the room.  I've always preferred long wall placement, and not all written advice contradicts that, the old Audio Physics speaker placement paper (not the new one presently on their website) indicated long wall placement to send early reflections at the listening position beyond a specified time window.  You've shared your room size and placement so I fully agree that you've got it right on that count.

However in my latest room, a dedicated small room, rectangular, I tried for months to get an acceptable long wall placement using every technique and wall treatment known to man.  Never could get it right.  In desperation I tried a short wall placement and bingo, right on the first try.  I traded width for depth in soundstage to be sure, but all the slap echo and resonant problems disappeared.  I finally can get even frequency response and excellent soundstaging.  So I learned the lesson that the room makes it's own decisions sometimes.     

rbbert

Re: Speaker placement........
« Reply #11 on: 8 Jul 2012, 05:46 pm »
Speaker positioning doesn't really follow any "Golden Rule" as Cardas might have everyone think. He didn't come up with anything, the Golden Rule of .6 to 1 to 1.6 has it's beginnings in biblical times...


Wayner

And I wasn't endorsing the Cardas speaker placement method (which I don't use), just his choice of optimal room dimensions.  It doesn't really matter when the "Golden Ratio" was discovered, its applicability to audio still applies.

Wayner

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Re: Speaker placement........
« Reply #12 on: 8 Jul 2012, 07:49 pm »
I'm gonna bet that it's all about high frequency off-axis response that may force the owners hand on the long/short wall debate. I do think that if someone is not quite happy with the sound they are getting from their present set-up, a little time and effort can make for a zero cost improvement.

Currently, I have 9 sets of speakers in the house. 1 set are MartinLogan ESLs that seem to have their own rules to some degree. If you get them too far apart, the sound-stage develops a hole very quickly. My Paradigm Studio 40v.3's are another odd duck. They want nothing to do with any toe-in and are more then happy at inches more then 5 feet apart. I suspect they would work great on the short wall.

My modded Dynaco A25XLs love being very far apart with about 7 degrees of toe-in. They are extremely 3D and can produce a stereo effect in literally any seating position in the room.

rrbert, I'm not endorsing Cardas either. I think his suggestion of using the Golden Rule ratio has some merit for initial set-up (you have to start someplace, right?) and then you adjust from that point. You can use his .267 x wall length for either the long or short wall. Again, a good place to start, maybe not to end.

Wayner

rbbert

Re: Speaker placement........
« Reply #13 on: 8 Jul 2012, 09:10 pm »
Actually it's only the golden Ratio room dimensions that I am endorsing.  I tried his speaker placement suggestions and have ended up (literally) feet away from them.

Russell Dawkins

Re: Speaker placement........
« Reply #14 on: 8 Jul 2012, 09:26 pm »
I favor wider than normal speaker spacing, if only to allow proper playback of recordings made Blumlein-style (like most of mine). Proper playback of these requires the speakers be 45º left and right of center.
I also seem to have greater success with space to the side of rather than behind the speakers, if I have to choose between these two.
So far, every time I have compared configurations across rather than along a narrow room, across wins, easily.

I take from this that - at least for my taste - space to the sides sounds better than space to the rear.

I follow the same principle when recording an ensemble in a rectangular room, where I can place the musicians anywhere. I will choose a central position, oriented with the greatest distances to reflecting surfaces to the sides.

Here's an example:




I do know that every time I see a setup with the speakers close to the side walls in a narrow room, I reflexively cringe!

rbbert

Re: Speaker placement........
« Reply #15 on: 8 Jul 2012, 10:19 pm »
What do you consider "close"?  2'? 3'? less?

Russell Dawkins

Re: Speaker placement........
« Reply #16 on: 8 Jul 2012, 10:30 pm »
I'd say less than 6' if the speakers are firing straight ahead, but less than 2' if properly toed in, and by that I mean so the axes cross at or in front of the listening position, unless it is sufficient to have proper stereo only down the exact centerline of the listening zone.

I have heard good sound down the long dimension of a room where there is a lot of space behind the speakers - where the speakers are 1/3 to 1/2 way down the room and the listening position is similarly forward of the rear wall - partly because, I presume, the room is somewhat removed from the equation by the proximity to the speakers and the distance from the speakers to the reflecting surfaces is increased.

dB Cooper

Re: Speaker placement........
« Reply #17 on: 9 Jul 2012, 12:55 am »
Along with all the other variables, dispersion plays a part. When I had Allisons, which had phenomenal (forward-omni) dispersion, I placed the speakers along the long wall and got a great stereo image from anywhere in the room. Other omnis (Ohms etc) may do the same. Omnis do tend to give up some of the "pin-point" quality some people like though.

NIGHTFALL1970

Re: Speaker placement........
« Reply #18 on: 9 Jul 2012, 02:54 am »
I have my magnepan 1.7s along the long wall in a raised ranch.  They face the opening to the stairway.  I had to put sonex behind them and behind me to eliminate the echo I was getting.  I don't use any toe in as that makes them brighter.  They used to be along the short wall of the room,  but they sound much better along the long wall.  I agree with Wayne that you have to experiment and use what works for your room.

jimdgoulding

Re: Speaker placement........
« Reply #19 on: 9 Jul 2012, 03:13 am »
That's the value of places like this.  Good topic, Wayner.