SETTING-UP SPEAKERS IN A RECTANGULAR ROOM

SETTING-UP SPEAKERS IN A RECTANGULAR ROOMBy George CardasVery precise speaker placement can open up a whole new dimension in listening, so I will outline the system that isbecoming the standard of the industry. This standardized listening room is a Golden Cuboid and is the model ofmath used in the system. This method will work with any panel or box speaker, in any reasonably sizedrectangular room. You may find that you have already positioned your speakers this way by ear.Diagram AActive nodes are the main concern when placing speakers in arectangular room. A node, or the frequency where speakers andparallel walls interact, is proportional to the speaker to the walldistance.The three most importance nodes, in order of importance, areproportional to the distance between the speaker and:1. The side wall nearest the speaker2. The rear wall3. The side wall across from the speakerA secondary factor is the speaker-to-speaker time constant.When you use this method to set your room up, the speakers areplaced so the three nodes progress or differ from one another inGolden Ratio. This eliminates any unison or near unison resonancein the nodes.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 behindthe 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)1. The distance from the center of thewoofer face to the side walls is:Room Width times .276 (RW x .276).2. The distance from the center of thewoofer face to the wall behind thespeaker is: Room Width times .447(RW x .447).This is all you need to know to placespeakers in a symmetrical, rectangularroom. Don't look at diagrams B, C, D,and E until you have your speakers inposition, because it will make yourhead explode!

For those who must know more Diagram BPlacing speakers in this manner will set all the nodes in Goldenprogression. Final focusing can be done from the near fieldposition (Diagram B)The importance of symmetrical speaker placement in a smallroom cannot be over emphasized. Once the speakers are set asclose to perfect as possible, you must angle them slightly towardthe listening position. This can be done by ear and usually a 1/4to 1/2 inch tweak will do. Box speakers generally require a bitmore toe-in than planear speakers. You will be able to hear acenter focused voice clarify when the sweet spot is hit.Golden Cuboid Listening RoomThe Golden Cuboid listening room (Diagram C) is 10' x 16' x 26'(Read 10.000 x 16.18033989. x 26.18033989.It's dimensions differ in a Golden Ratio or Fibonacci sequence (58-13-21-34.). The three major room nodes progress or differ inGolden Ratio and thus null rather than add or beat.The math used to create the dimensions of the Golden Cuboidlistening room can also be applied to speaker placement, speakerbox size, or for that matter, the conductors in your audio cable.Doing so will make the node progression an irrational or Goldenprogression.Diagram CIn the near field position the speakersand the listener's head are the points ofan equilateral triangle. Near fieldlistening gives the perfect stereo field. Itis frequently used in the recordingstudio to position the microphones andthe voice in the mix. The near fieldlistening position is determined by the"center to center" distance of thespeakers and the distance to thelistener's head. It does not refer to theroom in any way.The Golden Cuboid listening room is10' x 16' x 26' (Read 10.000 x16.18033989. x 26.18033989. It'sdimensions differ in a Golden Ratio orFibonacci sequence (5-8-13-21-34.).The three major room nodes progressor differ in Golden Ratio and thus nullrather than add or beat.The math used to create the dimensionsof the Golden Cuboid listening roomcan also be applied to speaker placement,speaker box size, or for that matter, theconductors in your audio cable.

Diagram DIn the case of our listening room, the relationship of potentialnodes or energy storage units can be expressed as a ratio(Diagram D), or a Fibonacci progression (Diagram eaker to side wall:RW x.6185.276Speaker to rear wall:RW x18.447Speaker to opposite wall:RW x1.61813.724Speaker to speaker:RW x18.447The Golden Ratio room set-up can beseen as a Golden Progression.Diagram EGolden Ratio can be derived from an exponential progressionknown as the Fibonacci sequence or summation numbers:1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 etc. The farther you go,the closer the distance between the numbers approaches theratio that can never be reached: 1.618033988 to infinity, to 1.The Golden listening room is 10' x 16' x 26'. This can be reducedto 5 x 8 x 13.The Golden Ratio room set-up can beseen as a Fibonacci sequence.

Diagram FIf you are forced to place your speakers onthe long side of a symmetrical, rectangularroom, create a Golden rectangle in eachrear corner. Your speakers can then beplaced anywhere along a line extendingfrom the outside rear corner through theinside front corner (Diagram F).Golden Rectangles, 1.618 from the side walls x 1 from the rear wall,create diagonal lines for speaker placement in a horizontal room.Diagram GIf you have the misfortune to have asquare listening room, as above, createGolden Rectangles in the rear corners ofthe room. Your speakers can then beplaced along lines extending from theoutside rear corners through the insidefront corners (Diagram G).Golden Rectangles, 1.618 (side wall) x 1 (rear wall) on one sideand 1 (side wall) x 1.618 (rear wall) create diagonal lines forspeaker placement in a square room.

Diagram HThe Golden Cuboid (Diagram H) is thebest "rectangular" shape for a listeningroom. If, however, you have fullarchitectural freedom, a Golden Trapagon(Diagram I) is by far the favored shape. AGolden Trapagon has a Golden rectanglefor the front wall behind the speakers, andthe room progresses to a larger (by GoldenRatio in area) Golden rectangle back wallbehind the listener.For example, if the wall behind thespeakers is 10 feet x 16 feet, the roomwould then be 26 feet long and the wallbehind the listener would be 13 feet x 21feet. Ideally, the rear portion of this roomwould vent into an attic space filled withfiberglass insulation.The trick to a Golden Trapagon shapedroom is it eliminates the problem ofparallel walls and the slap and sharp nodesassociated with them. The "sound" of thisroom is a decaying hologram of theoriginal, not a slap. This decay isexponential, or higher, at all frequencies.The relationship between the height andthe width of the room, at any point, isGolden Ratio. The cross-section area at therear of the room is 1.618 times the crosssection of the front. In the example above,the ceiling height would be 12.72 feet.The ratio of front height or width, to rearheight or width, is 1.272 to 1. 1.272 is thesquare root of 1.618 or Golden Ratio. Theprogression of size at the ends of the roomis a area relationship. The sound confrontsthe entire surface of the end walls at thesame time, rather than progressively aswith height and width. It is like tuning aguitar to a major chord, the side wallsbecome the strings and the end walls arethe bridge and tailpiece.Cardas Audio, Ltd.480 Eleventh Street, South EastBandon, Oregon 97411Voice: 541-347-2484Fax: 541-347-2301http:/www.cardas.comDiagram I

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 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. Speaker placement .