< previous - 1 - 2 - 3 - 4 - 5 - 6 - next >

Ed's AV Handbook
Batting practice for the AV Professional
and primer for the novice

Chapter 6  Page 4

The Room, Speaker, & TV
The Speaker System

JBL L100

Speaker facts

A larger full-range speaker is more fun and better than a smaller speaker.  A smaller speaker shears the bottom two or three octaves of your music or movie soundtrack.  This smaller speaker is analogous to cropping the bottom third of a photo.  More precisely, downsizing to a smaller speaker is the equivalent of removing much of the red pigmentation or hue from a treasured painting's color balance.  Smaller speakers do not reproduce a complete audio picture.

If a speaker accurately reproduces acoustic music, it will also accurately reproduce movie soundtracks.  The inverse is not necessarily true.  A movie soundtrack typically includes a wealth of artificial sound effects.  What is the sound of an actual dinosaur?  Although our children may not believe us, we do not, in truth, know.  However, music is real.  Therefore use music as the reference to judge a speaker's fidelity.

A speaker placed at ear level sounds better as a painting or photo looks best when viewed at eye level. 
And proper speaker placement will minimize problems created by room modes.

Speaker and listener placement

Richard Hardesty 'the Audio Perfectionist' stated, "The goal of optimally positioning the speaker and the listener within the room is to make the sound from the speaker more prominent, and the sound from the room less prominent."  The speaker's distance from a room boundary is the lead issue.  It is inversely related to the level of the reflected sound's amplitude.  That is, the reflected sound is louder if the speaker is closer to a boundary, less loud if it is farther away. 

Therefore, move the speaker away from the room boundaries, particularly the wall behind the speaker.  Three feet is a minimum recommendation.  More is better.  However, the placement of the speaker should also avoid problem room mode peaks and nulls.   The following will guide you through the maze of acoustical obstacles.   Begin this project with a sketch of your floor plan.

Left and right speaker placement. 

I was introduced to the following procedure many years ago by my late friend Steve Mounkes. 
As will be explained in more detail in Chapter 7 -- this may be the most practical audio application offered on this website. 

Calculate, and choose feasible front left and right speaker positions.  First, measure the width of the room.  Divide this measurement by the values 3, 5, 7, & 9.
Use the results to measure and mark points along the width of the room from the left and then the right corner.

Next, measure the length of the room.   Divide by the odd values.  Use the result to calculate the room length points.
Mark these points along the room length from the front and then right corner.

Now observe the on-floor coordinates established by the width and length points. 
While avoiding equal coordinates, choose a practical pair as positions for your front left and right speaker.    

(The home theater layout on the next page outlines this calculation)

Locate the sweet spot

While avoiding room mode peak and nulls, place a chair with the front left and right speakers in an equilateral triangle.  This arrangement creates an inclusive angle of 60 degrees, from the chair to the front and right speakers.

Stereo Sweet Spot

While seated, listen to a stereo recording.  Move the chair slightly forward or back of the initial position.  Adjust the cant or focus of the speakers toward the listener.  The sweet spot or optimal position is at the point where the stereo recording falls into stereo focus.

The listening position for stereo is also the ideal seating location for a surround sound system.  However, additional seating is probably desirable.  Therefore, carefully select additional-positions that are comfortable and practical.  But avoid room mode peak and nulls.  More on this later.

Next step

If your system is stereo music only with a subwoofer, then move ahead to Subwoofer Placement. 
If it is a stereo audio-video system without a subwoofer, then skip to The TV.  If it is exclusively stereo music without a subwoofer, then skip to Loose Ends.  If your system is a multi-channel surround system, then continue with the remaining speaker placement instructions on the next page.

< previous - 1 - 2 - 3 - 4 - 5 - 6 - next >
Ed's AV Handbook   
Copyright 2007 Txu1-598-288 Revised 2021


SandTrap Audio Logo

Architectural Speaker Tuning System
for in-wall/ceiling custom installed speakers.
Reclaim the performance you paid for.