Quick ways to determine optimum positioning


Guys I am looking for some advice to determine the optimum positioning for my speakers. Also if you have some secrets on cheap room treatments, espicially for a sliding glass door that seems to disrupt my sound imaging.
Thanks,
Mat
biggytaz
Install full length double drapes across the doorway. Try the Cardas method to determine initial speaker placement.
http://www.termpro.com/programs/archive.html

That link will have a menu of free downloadable programs, many for designing loudspeakers, however there is one for speaker placement. That link is from georgia audio labs at www.audiolabga.com

Quick guidelines, make sure the distances from the back wall and side wall near the speaker are not the same. Keep at least 6 feet between the speakers. Try to get a minimum of 2 feet, preferable more, from sidewall, same applies to back wall. As far as listening wall, where your sitting, stay out from the rear (listening) wall several feet (although one school of though recommends being flat against the listening (rear) wall, this is debatable. My setup is like this by no choice of my own, it'll certainly give you low end reinforcement-I don't recommend it). Get a more or less equalateral trianlge between the speakers and you. You may end up sitting a little closer, or a little farther away. Have speakers firing straight ahead, from there experiment with slight toeing in. (There are other extreme methods of having the speakers pointing directly at the listner or even crossing thier axis somewhere in front of the listeners face --I would avoid those). Take all measurements from the midpoint of the front edge of the speaker cabinet (this is where the sound is coming from). If its a time aligned designed approximate the midpoint somewhere in the middle of the axis slope where all the drivers from are from an aerial view, you're trying to find the point at which all the voice coils are lined up.

Positioning for dipolars, bipolars, electrostats, certian horn designs, and any other design with some peculiarities, such as NHT's big speakers, need to go by certian rules specific to that design.

For that glass window, Some nice vertical blinds might help diffuse the highs when slanted (hey they're tunable) short of resorting to impractical methods (like covering the window with foam). Paintings, wall hangings, tapestries, other stuff help absorb and diffuse sound so if done properly you shouldn't need acoustic treatment. Should you opt for, basic foam at the first reflection points on the sidewalls are most important, i.e. the point where if you placed a mirror on the sidewall you could see the tweeter from the listening position, it won't be halfway, closer to the speaker. Second most important area is the wall directly between the speakers on the back wall. Third is the listening wall directly behind the listeners head. Those are the areas to treat with home stuff if possible. If resorting to foams, 2" at those points is good. The following links are good places:

www.auralex.com
www.silentsource.com
www.echobusters.com
And then RPG and ASC (www.tubetrap.com?) have websites too.

If you go homebrew, jon risch has some ok designs. Bass traps probably aren't necessary although maybe. Do not use the "eggcrate" foam designed for your bed. Its absorbtion nrc. measurements are horrible (like .40) its ugly, and for what you paid for it you might as well have bought a basic package of acoustic foam that will do the job right without having to cover as much of the wall. The rpg starter kit is ok, it used to be a good deal when it was $50, now its up to $75 but still maybe the easiest thing to do. Look around though.

my 2 cents.
I will just add a little to the excellent advice above. I agree with not pointing the speakers directly at you but I would try turning them to the point where they almost point at you. I find this best for my set up.

Also take the time and aggravation to get the speakers as symmetrical as possible. To the inch. The closer you get the better they will intergrate with each other.

It takes me a few months of tweaking an inch here and an inch there to get them just right. But when you do its the equvilant of a speaker upgrade.
If you have a Menard's Hardware Store near you, check out a part #244-5304. This is sold under their "house brand" of products called "Tool Shop" and is a combination 22" aluminum Laser & Bubble Level. The EXTRA "cool" thing about this one is that it comes with a couple of different rotatable attachments. One attachment can project lines instead of the typical dot that you see so often. Using this device and a tape measure and a piece of wire, you can then position your speakers VERY precisely.

Making sure that your speakers are level is one specific part of the project. This assures you that they are firing with the same vertical radiation pattern and are not "leaning", "distorting" / "tilting" the image. Then you can adjust their overall height. This is done by comparing the horizontal laser line height of each speaker against a back wall or cardboard plate attached to your listening area, etc... This assures that the speakers are firing along the same horizontal plane. This same horizontal line can be used to "focus" the spray angle of the speaker and the appr area of coverage. Just don't take for granted that your speaker radiates as wide or narrow as the line being projected : )

You might not believe the differences that doing something like this can make. I am overjoyed with the results to say the least. I experimented with the mains in my HT system and was amazed at how much more "cohesive" and "natural" it sounded in two channel. Imaging / localization was DRASTICALLY improved and far more stable.

Keep in mind that you need to be able to keep the speakers at an equi-distant angle from the listening position as you're doing all of this. A piece of wire placed from your seated listening position that you can swivel back and forth between the L & R speaker baffles works best although it is not as convenient as using string. Only problem with using string is that it stretches as you pull it tight and you might develop some small irregularities from relying on such a measuring device.

I picked mine up on sale last Sunday ( Dec 2nd ) for just under $30. I don't know if they are still on sale or not, but i think that regular price was either $40 or $50. While you can find other "laser levels", make SURE that it has the potential to project a line and not just a dot. The dot can be useful but not nearly as much as the projectable line is. Hope this helps... Sean
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