My favorite speaker placement formula...

I couple of friends have asked me about speaker placement which I find is highly critical to getting the most out of your system. I've been using the Cardas Golden Ratio placement formulas so I thought I might add it in here given the interest in new speakers on the board. May I suggest nailing the exact effective location for these new toys is an important next step...

http://www.cardas.com/content.php?area=insights&content_id=26&pagestring=Room+Setup

Setting Up Speakers In A Rectangular Room
by George Cardas

Very precise speaker placement can open up a whole new dimension in listening, so I will outline the system that is becoming the standard of the industry. This standardized listening room is a Golden Cuboid and is the model for the math used in this system. This method will work with any box speaker, in any reasonably sized rectangular room. You may find that you have already positioned your speakers this way by ear.

Active nodes are the main concern when placing speakers in a rectangular room. A node, or the frequency where speakers and parallel walls interact, is proportional to the speaker to the wall distance.

The three most importance nodes, in order of importance, are proportional to the distance between the speaker and:

1. The side wall nearest the speaker
2. The rear wall
3. The side wall across from the speaker
A secondary factor is the speaker-to-speaker time constant.

When you use this Golden Ratio method to set your room up, the speakers are placed so the three nodes progress or differ from one another in Golden Ratio. This eliminates any unison or near unison resonance in the nodes.

Panel or dipole speakers such as Apogees and Magnepans cancel their side waves, so a formula of .618 x the ceiling height can be used for determining placement from the rear wall. Most box speakers radiate low frequencies in all directions thus a formula that places the speaker to rear wall distance at 1.618 the side wall distance should be used.

Speaker placement, simply stated

The distance from the center of the woofer face to the side walls is:

Room Width times .276 (RW x .276)
The distance from the center of the woofer face to the wall behind the speaker is:

Room Width times .447 (RW x .447)
This is all you need to know to place speakers in a symmetrical, rectangular room!

Diagram A

Distance
Percentage
Speaker to side wall: RW x .276
Speaker to rear wall: RW x .447
Speaker to opposite side wall: RW x .724
Speaker to speaker: RW x .447

 

The Cardas method is based on your speakers firing down the room. If your speakes fire across the room, Cardas basically say "feggeddaboutit" with their method, before throwing a small bone to people so (in their opinion) afflicted. (Yes, I have my speakers firing across the room and I like it!)

 

From an acoustical standpoint you really want to have your speakers fire down the room. Sometimes other considerations like apartment living, wife acceptance, etc. get in the way however.

I do wonder if your across the room layout impacts your view of certain equipment...that could be good or bad depending on the end user's own similarity to your situation...

 

Does firing accross the room simply mean that the sound is directed to the middle of the room, instead of the listener's ears? If that's the case, I have that kind of setup too with my new Ohms...

 

Aman, the phrase "firing down the room" means that a line drawn between the two speakers is perpendicular to the long axis of the room. Which is the same as saying the back wall (behind the speakers) is the short wall.

"Firing across the room" means that the back wall is the long wall.

As LeeS says, this arrangement is often more useful in an apartment. I have such a layout, but the speakers are pulled a fair way out from the back wall. Although it sounds good, I've often wondered what the sound would be like the other way. It certainly would not "work" very well in my 26' x 13' x 8' living room, but I'd still be interested. Just one of those projects I need to get to one day.

 

Gary,

Good question. You have an almost square room. Cardas would probably say that you really want a golden ratio rectangle but none of us normally has that. I think a rectangular shape of any sort is better purely from a standpoint of minimizing room "nodes" which can impact the sound. I think you could still apply the Cardas formula anyway, however, but maybe not get the best possible results. Experiment!

 

I would have argued the other way around. Firing across the room normally allows the user to set up the speakers with differing distances to the floor, rear and side walls, which is a good thing. Firing down the room, it is much more difficult to achieve this. Firing across the room, I get far less sidewall bounce than firing down the room.

I've found that I get better sound in my room by using the setup I have.

Of course it does, just as firing down the room does. I fnd that I have more even and less boomy bass with speakers firing across the room.

The best sound I've ever had from my Epos ES14s was with the speakers half way down or across the room (didn't seem to matter which). But even a hi-fi scribe, living on his own, found these arrangements to be a bit much, visually and for using the room.

 

I'm not sure that this is true Michael. All the acoustical books and experts I have talked to have always recommended a rectangle with speakers on the shorter end.

That is not to say you can't go the other way and still get good sound, just not the best sound.

 

This may be of some value:

http://www.rivesaudio.com/files/spkr_plcmt.pdf

Also...

http://www.audioholics.com/techtips/roomacoustics/perfectaudioroom.php

 

Also of note:

http://www.audioholics.com/techtips/roomacoustics/designinglisteningroom.php

 

I have a small dedicated listening room that's rectangular (although not optimal proportions) and used the Cardas method in placing speakers that LeeS posted. I think it works really well, stereo imaging is much better than with any other configuration I tried.

 

I apologize, I was in fact wrong. I called did some research and in fact you can use the long side of a room if you have certain dimensional ratios. I will publish the ratios soon.

 

In my experience, the Cardas formulas works pretty well for good soundstaging, but not necessarily for optimum tonality. You may need to place the speakers closer to the rear wall than what the formula says to achieve the very best results. Trust your ears. IMO they are the best formula to use.

 

Agreed, Randy W...I (like most) tweaked the formula placement a little to improve certain aspects of tonality. But even then, more than moving the speakers much from the Cardas formula placement, which I found really was almost dead on with what sounded right to me, adjusting for optimal tonality was mostly a matter of just playing a little with the amount of toe-in of my speakers, until things sounded tonally right but the soundstage was still accurate too. It could be personal preference - I don't find I like the increased bass sound that one gets from moving speakers closer to a wall, especially for acoustic bass on jazz recordings, it always sounds boomy to me, never sounds natural or "right"...so I am happy with a little lighter bass than most people I know seem to prefer, meaning the Cardas formula fits my ears to a T.

 

Dynamics, "snap", and focus are other areas besides bass and tonality that are affected by the speaker's distance from the rear walls, distant apart, and toe. We all become acclimated to what sounds "right". Sometimes what sounds unfamiliar is actually better in the long term. The best tonality and dynamics in speaker placement usually come at a price - less soundstage depth. If you find yourself marveling at your speakers imaging, but not swaying your head and tapping your feet and hands - you know what I mean.