Ed's AV Handbook.com
Home Theater & High Fidelity Stereo Audio


Chapter Six
The Room, Speaker, & TV
Page 4

Batting practice for the audio/video pro and a primer for the novice
 


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The
Speaker System
 

Speaker facts
          A bigger full range speaker is better than a smaller speaker.  A smaller speaker will shear the bottom two or three octaves of your favorite music or movie soundtrack.  This 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 can accurately reproduce natural acoustic music, then it will accurately reproduce movie soundtracks.
 A substantial measure of a movie soundtrack is made of artificial sound effects.  And though our children may not believe us, we do not know what a dinosaur actually sounds like. However, music is real.  Therefore, use music as a reference to judge a speaker’s fidelity.

          A speaker should be placed at ear level and away from room boundaries.  A speaker placed at ear level sounds better, as a painting or photo looks best when viewed at eye level. Proper speaker placement will minimize problems created by the room’s acoustics.


Speaker and listener placement
          Richard Hardesty, the Audio Perfectionist, stated, “The goal of optimally positioning the speakers and the listener within the room is to make the sound from the speakers more prominent and the sound from the room less prominent.”
          The initial issue is the distance from the speaker to a room boundary.  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.  It is 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 and the listener should avoid problem room mode peaks and nulls.

          The following directions will guide you through the maze of acoustical obstacles.
Begin your project with a sketch of the floor plan.  Identify the room mode peak/null points of each dimension.  Then proceed with the following.


Front 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.
          C
alculate 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, and 9.  With the results, measure and mark these points along the width of the room from the left corner and then the right corner.

          Next measure the length of the room.  Using this dimension, calculate the room length points.  Divide by the same odd values.  Mark these points along the room length from the front left and right corners.  
          Now observe the on-floor coordinates established by the width and length points. While avoiding coordinates that are equal, choose a practical pair as positions for your front left and right speaker.


Locate the sweet spot
          While avoiding room mode peaks and nulls, place a chair with the front left and right speakers in an equilateral triangle.  This creates an inclusive angle of 60 degrees from the chair to the front left and right speakers.  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 listening 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 peaks & nulls.
          If your system is stereo only with a sub woofer, then move ahead to Sub woofer Placement.  If the system is a stereo and video system without a sub woofer, then skip to
The TV .   If this is a stereo music-only system, then advance to Loose Ends.  If the audio system is a multi-channel surround system, then continue with the remaining speaker placement instructions in the next page.

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Ed's AV Handbook.com
Batting Practice for the AV Pro and a Primer for the Novice.
Copyright 2007 Txu1-598-288   Revised 2018