Near field listening and speaker placement


We have a large music room (20x30) with a cathedral
ceiling and front outside wall angled out at 105 degrees,
(typical contemporary) with a tall bank of windows. In
order to avoid interaction with the glass, speakers must
be placed along short (20FT) axis of room. The room is
live (hardwood floors), although we have thick wool 9x12
rug in front of speakers

We would like to use a near field listening configuration,
and have several questions:

1. We assume nearfield listening is an attempt at zero
interaction with boundaries so that only direct path sound
arrives at the ear. Is this the consensus, or have we
overlooked something in the definition?

2. Speakers are placed 6 feet from the "back" wall. What
is the result of eliminating the back wall from the
listening equation?

3. In order to minimize interaction with the floor (the
closest boundary) should we worry about carpet on the
sides and behind, not just in front of our speakers?

4. Are there a canonical set of rules for spatial
optimization in near field set ups?

Guidance from the experienced is much appreciated.
hindemith
Hey check out the speaker placement guide on Cardas.com and more importantly for what your asking immedia.com. The immedia setup guide speciffically gives a guide on nearfield placement...
check out:

www.immediasound.com

in the Audio Physik section. AP specializes in nearfield listening.
Hello. I listen in near field. I have a very small listening room, 9' x 12'. I have a pair of Mirage MRM-1 Reference Monitors. I played with placement for weeks. What sounded best was the factory prescribed "rule of thirds." Listening position is 1/3 off the rear wall (into the room), speakers 1/3 off the front wall (rear and front refer to the 9' walls). This really cleaned up my room, eliminating most of the room anomalies. Only room treatments or room correction devices can really clean up the anomalies.

There is another school of thought. Speakers are placed in the middle of the room, with the listening position against the rear wall.

Near field = soundstage city.

1. That is my understanding as well. Be forwarned, near field is a bit like headphones, really big headphones.

2. My MRM-1's are rear ported, so they needed to be off the rear wall. Use rear wall distance to adjust your bass response, especially to get rid of mid bass boom.

3. I'm no expert, but I would assume more carpet = less reflective surface = quiter room. You've got the main area taken care of, though.

4. see above

I hope this helps. As previously stated, I'm no expert. This is just my own imperical data. Happy listening.

Erik
The Audio Physic website has excellent suggestions and rational on setting up loudspeakers in a room.

http://www.audiophysic.de/produkte/aufstellung/aufstellung_e2.html

Peace,
Ross
I think your questions are impossible to answer over the net. Like a Dr. ( I ain't no Dr.) trying to diagnose over the phone, But:

1) Yes that's the idea but there is always reflected sound. And you will not "aviod" interaction with the glass in a room that size no matter what the placement. You can reduce it.
2) See articles mentioned below
3) Will take experiments but probably yes.
4) Yes, See Cardas article below and Art Ludwig's site.

There are lots of theories on placement but all of the people I have talked to indicate that it is very room, taste, and system specific. Even with the best theory it takes a lot of moving stuff around.

You will definately have to work on the hardwood floor and glass with coverings if the entire floor is hardwood and the windows dominate a wall. I have heard some really nasty systems in this kind of room if not damped (Sorry). A very good short explanation of the classic "near field" set up by George Cardas is at www.audiolinks.nl/speakersetup/speakersetup.htm

A short piece by Joachim Gerhard (audio physics) is at www.speakerbuilding.com/content/1039. Gerhard suggests placement more toward the middle of the room than the classic placement that is described at the first site mentioned.

There is a wealth of information and recommended reading on this topic at Art Ludwig's site. www.silcom.com/~aludwig.

Good Luck

Sincerely, I remain
One thing to keep in mind--If you have large speakers where the drivers are spaced relatively far apart they may not be suitable for nearfield listening as the drivers might require some distance for their sound to mesh into a coherent whole. Just another thought.

Tim
jfrech, ivanj, Creeper, Rosstaman, Clueless,

So much, to the point, so promptly. Thanks for the
guidance and websites.
Was about to state Soix's point.
I listen to 3-ways in a 7.5' triangle in a 14x24 room.
The speakers are 8' out from the front wall.
I tried several serious 3 ways (N803, N804, Ariel 8, Revel F30, VA Fidelio) before deciding upon my choice (Parsifal Encores).
The Ariels and ESPECIALLY the Nautilus' had SERIOUS problems in the nearfield due to lack of coherence. The Revel F30 was pretty darn good, but my wife hated the California moderne looks. The Fidelios didn't work because their rear-firing woofs needed boundary reinforcement, and 8' is WAY too far away. So this can get tricky unless you take the easier route with excellent two-ways or at least 3-ways with a low cross.
Damping the room much more than you have is my strong preference, but you may be able to get decent sound in the nearfield. Controlling sidewall splatter with toe-in and speaker selection for off-axis response characteristics will be important. (You DON"T at all have to have a headphonesque stage...quite the contrary.)
I'm fortunate that my 7.5' triangle throws a stage about
12' wide and easily 10-15' deep!---WAY beyond the speaker positions. I use stuffed sofa and chairs with throw pillows
propped on top of them where windows and fireplace are at first reflection points. Wall-to-wall with pad is HIGHLY recommended, and a cross-beam ceiling doesn't hurt either.
By contrast my 14x14 cathedral-ceilinged hardwood-floored, multi-windowed familyroom system sounds like crap!...but it sure plays loudly! For TV that's fine...makes the "action" seem bigger, and for 2-channel HT that's ok.
But for serious music reproduction deader is better, and to repeat, ultra-coherent speakers in the nearfield just improve your odds of aquiring a stage and frequency-response
close to the designers' intent.
Good luck.
You also don't want a flat wall behind your speakers no matter how far out they are, I put 3 fig trees between and behind the speakers for dispersion and the soundstage and imaging improved...
In case anyone is still listening:

I am especially interested in the observations made in
this thread about speaker coherence and near-field
listening.

1. Is coherence a function of the spatial field set up by
the speaker for low vs. mid+high frequencies? What
specifically are you referring to as speaker coherence.
My understanding of a pair of coherent sources
from physics, does not appear to be relevant here.

2. How do you detect the effects of coherence? One of
my test&burn cd's has a listening test for "in phase"
vs "out of phase". Is one's ability to
distinguish "in phase" vs "out of phase" related to the
condition of coherence?
coherence as a consideration in near-field listening has to do with at what listening distance AND HEIGHT that the drivers meld together in a natural soundstage, proper balance, and phase coherence (some NEVER do). for instance in a tall line array like a Wisdom or Pipedreams you need to be further back for the drivers to "work" correctly. a single-driver Louther on the other hand, would be coherent at a much closer distance. some speakers never work properly in the near-field. you can experiment by starting at a few feet and slowly move back untill things sound "right". remember to also try different heights of your listening chair as you move back.

this issue is mostly related to the dispersion pattern of your tweeter as the high-frequencies are very directional. this is also why height is so important in the near-field on some speakers.

the biggest problem of near-field listening in a large space is the challenge of being able to fill the room with bass energy without blowing yourself out of your chair. for proper bass weight and warmth some room loading is necessary. if not properly addressed the sound can be thin and the "presense" and "weight" can be lacking.
I won't get into the technical aspects of coherence or why one speaker is better suited to nearfield listening than any other(mainly because I can't). But strictly from a listening standpoint you can tell when the different drivers of a given speaker come together as one complete whole, and that is what I meant in my post by coherence. In a speaker not well suited to nearfield listening(I agree with Subaruguru about B&W in this respect) with vocals in particular you can actually hear the midrange playing the midrange and the tweeter playing the highs rather than them coming together into one "coherent" or seamless sonic picture. This is why larger speakers where drivers can be spaced well apart from one another may not be good nearfield speakers--the drivers don't have sufficient distance to mesh before the sound reaches your ears. So, in short, despite the benefits of nearfield listening, if your speakers are not well-suited to this type of positioning you'll end up doing more harm than good with a nearfield setup. If you identify the speakers you're using someone here can probably tell you if it's worthwhile exploring this option.

Tim