Speaker Placement

Jumbo3, I spent nearly a year screwing around with speaker placement. The following method was given to me by a prominent speaker designer, and no matter how I alter my speaker placement, I end up getting the absolute best results, just as he told me. Here goes!

Note: This will usually require an argument with the wife over how the furniture is arranged, and will take you about an hour or so to complete.

First, your speakers if possible, should be adjusted exactly level from side to side and front to back before beginning the placement proceedure.

Keep a clearance of approximately 2 feet from the back wall behind the speakers. This however is not one of the most important dimensions to be maintained or obtained. They can be moved forward or backwards to comply with the next few steps if necessary.

Next, set the speakers as far apart as your room will allow. This distance however must be narrowed if their width cant comply with the next few steps. The wider the speakers are apart, the greater the sound stage. the speakers at this point should also be toed in to you sweet spot by eye. The toe will be adjusted in latter steps.

Now measure the distance between the speakers. center of one speaker to the center of the other.

Now from the center of your sweet spot, measure the distance to the center of each speaker. The distance should be the same as you measured between them. This is the most critical measurement!! You MUST, from the center of your listening sweet spot, measure to the face of each speaker, and get them within a 1/4 inch of each other, and that distance, would be the same distance you measured between the speakers. This will require you setting something stable in your sweet spot, so the measurements will be accurate and consistent. This is how you obtain imaging, and yes it needs to be within a 1/4 inch.

Next, after you have spent a 1/2 hour getting it the way I said, sit in your sweet spot, with a flash light on your head. Yes a flash light, and yes people will think you have lost your mind. holding the flashlight on your head, look straight ahead until the light is projected as what you perceive to be exact center. Then turn or roll your neck unitl the light is at your right or left speaker. the light should be at the exact center of the speaker. If not, toe that speaker in or out, and go back to your sweet spot, calibrate your head again to center, and do it again. when you get it right, the whole speaker face will almost illuminate. Do this for each speaker.

Once you have the towing right, recheck the distances from the center of your sweet spot to the face of each speaker. If it is out more than a 1/4 inch, move either one straight back, maintaining the toe angle, to get the distance right again.

So heres an example of what you should have at the end:

Your speakers are approximately 2 feet from the back wall.
Your speakers are 10' feet apart from each other at their centers. from the center of your listening posistion, each speaker is EXACTLY 10 feet away (+ - 1/4 inch) Your speakers are in perfect toe to your listening spot as determined by the flashlight method.

This will take you an hour for sure, if not more. When your done however, your speakers will be in their absolute correct placement. Its not a bad idea to write down your final measurements or somehow mark their posistions.

Good luck, let me know if you went through the effort and how it worked out. You wont be disappointed....Steve

Jim: You are right about the forumla. I've been considering putting up some type of formulation, but the problem I have is that it can be very dependent on other variables in a room and speaker dependent, and it's impossible to incorporate all of that. The CARA 2.1 software comes the closest, but it still doesn't take into account many speaker variations very well. As to your question about the diffusion material, in general I like diffusion behind the speaker (or front wall) and more absorbing on the rear (behind the listener). How high and wide should the material be depends on many things. The most important is the speaker size, placement, and rear dispersion pattern. Then you have to consider the rest of the room and how those diffracted and non-diffracted rays will interact with the rest of the room. Diffraction also behind the speakers in general should not be randomized. There are diffraction patterns that attempt to diffract all frequencies (not the lowest of course) in a randomized way. This to me doesn't really work with planers as they lose the rear reflection coherency. Someone once suggestion slats like blinds slightly tilted upward. I haven't tried this yet, but based on other diffraction (diffusor) methods I have used I suspect this will work quite well. I can't say for sure about the size you proposed (having little information about the rest of the room, etc), but it seems reasonable, and certainly a good starting point if you are doing this by ear. You might consider buying the CARA software (we sell it--so I am partial to it). I've found it to be very useful in situations such as yours, when you would like to know the answers for a select few variables (such as the size of a diffractor), it can get you very close, and show you what happens with speaker placement pretty reasonably without too much time involved.

Thanks, guys. I am just looking for a starting point so I don't have to chase my tail for a few hours.

Cardas'formula doesn't take into account a sloped ceiling, so, it's not clear what ceiling height to plug into the equation. But, melding everyone's input together suggests a distance of about 5 1/2 feet from the back wall and about 5 feet from the side should work as a starting point. (Although, perhaps the speaker's distance from the back wall should not approximate the distance from the side walls????)

Rivas, your formula wasn't on your web page so I don't know how it would campare to the other suggestions, but I will be incorporating your idea of diffusion. The only questions I have for you on that is: 1) Is it preferable to have the diffusion material directly behind the speaker and 2) what size range should the material be? (is 6'H x 3'W adequate?)

Again, thanks to all.

Jim

try HP's rule of thirds, 1/3 of 22 1/2 is 7 1/2 and 1/3 of 16 1/2 is 5 1/2 so, place the speakers 7 1/2 out into the room and 5 1/2 feet apart (At least 5 feet out into the room is necessary IMO). I know this is radical but the results in my system resulted in the best bass and continuity. At least use this for a starting point. BTW toe them in slightly and experiment with toe in, usually aim them just outside of your ears works with Maggies. I have 1.6's myself.

Try cardas.com for their golden room ratio's, speaker placement, etc.

Overall, it's an excellent start and pretty basic.

Jimbo: Planers are very finicky--they require far more attention to placement and environment than dynamic speakers do. The other aspect that is very important to planer is that symetric placement is critical to good imaging. I believe this is important for most speakers, but have found it to be particularly true for planers. This is contrary to what you may have read previously. We had a lot of people asking about speaker placement and have put a short tutorial on our website. If you go to www.rivesaudio.com and enter the site then click on acoustical issues. This will take you to the listening room, once there select speakers and you will get a link to that tutorial (the whole listening room is a tutorial--but the speaker section is probably of most interest to you). One thing that is not covered in the tutorial (as we wanted to keep it brief), is some of the things to keep in mind with planers. I already mentioned the symetry, but the other aspect is the rear wall. Most planers require something reflective but diffusive as well. Absorbing will dull the sound too much. The reason we didn't include this in the tutorial is that speaker placement of planers is very dependent on this rear wall. Changing the material on this wall will change the optimum placement and thus change the entire sound. If you read the tutorial, it discuss the iterative process in the width between the speakers and canting the speakers. For planers there becomes another variable, the rear wall material, which effects canting, width spacing, AND rear wall to speaker spacing. If you can modify the material behind the speaker I would recommend first overdamping that space dramatically (hang wool blankets or something) and listen and then place the speakers. They won't sound very good, but the point is to educate your ear on what overdamping does. Then do just the opposite, get something completely reflective behind them (wood doors work pretty well, even smooth plywood can be okay for experimentation). Again, this won't sound so good either. Lastly get something to diffuse, but not absorb the sound (If you can get full length shutter or wooden blind type material this works very well). The diffusor is most likely what you will want to use, but the process of listening to these should help you in your overall quest to find the best speaker placement and overall sound.

FWIW the last time i set up planers i had them in a room 13.5x19.5 firing down the length of the room with the center of the panel about 2.5 ft from the side wall and the speaker about 4.5 ft from the back wall with the panel turned inward half way toward the listening position. the listening position was mid way between the two speakers 4.5 ft out from the back wall. the sub was against the wall between the two speakers. caveat - this ain't a science, be prepared to do a lot of moving of the speakers. also i found it helped to have something behind the speakers that acted as a diffuser. good luck.

Hey Jimbo, I had Maggie IIIAs for 14 years and by trial and error I came up with the following:
-tweeters on the inside
-44in from the back wall
-tweeters 56in apart
-toe in panels toward center listening spot

Start with these measurements and then tweak them an inch at a time to your preference. Hope this helps.

I have not had planars before, but here's what works best for me...

Try the rule of thirds, pull them out about a third of the way into the room, and about one third of the way away from the side walls. That is a place to start. Then use your ears. There are no formulas that are better than your ears because they can't take into account your room and furnishings. That's how I've had the best luck.