37
User's Manual
The Holographic Image is a unique
process which enhances the three-dimen-
sional effects and realism of stereo sound.
This circuit was designed to overcome a
problem in obtaining accurate sound repro-
duction:
In a stereo system, both ears will hear
the output from both speakers. The left ear
hears sound from the left speaker and from
the right speaker. To see a problem with this,
compare what happens when listening to a
live musical performance:
During a concert, each ear will receive one
direct sound arrival. For example, a cymbal
crashes, both your ears will hear it and the
brain tells you accurately the position of the
musician. In a stereo recording of the concert,
this cymbal crash will be heard from both
speakers. The left ear will hear the left speaker,
which is fine, but it will also hear the crash from
the right speaker. These extra sounds tend to
confuse the sense of sound source location.
The stereo effect in a good pair of
headphones is enhanced because the left ear
only hears the left headphone, and the right
ear hears only the right headphone. There
are no extra sound arrivals.
To summarize :
1. A real musical event will create only
two direct sound arrivals, one at the
left ear and one at the right.
2. Stereo playback will give four arrivals ,
as both speakers are heard by each
ear. These second sound arrivals
reduce our naturally accurate sense of
positioning.
The Holographic Image circuit was
designed to cancel out the unwanted second
arrivals. The left ear will mainly hear the left
speaker and the right ear mainly hears the
right speaker. This is accomplished by
sending a complex crosstalk signal from the
left and right speakers in addition to the
normal program. These extra signals are
virtually identical to the unwanted second
sound arrivals but they are out-of-phase with
them and they cancel each other out.
The result is a more three-dimensional
and wider soundstage, where the positioning
clues are restored. In a way, the musicians
have been freed from the confines of the flat
plane between the speakers. You will per-
ceive them as playing forward or playing
behind the speakers or to one side or the
other, not just somewhere in between. We
recommend that you experiment with its
effect, remember that you are listening for a
more accurate sense of the location of the
different musicians.
Because the Holographic Image works by
phase cancellation of the unwanted second
sound arrivals, accurate speaker positioning
is required. You must make sure that the left
speaker is the same distance away from you
as the right speaker. Follow the front speaker
placement on Page 24 to get the best results.
This is the same as any standard stereo
system only with more care taken to position
the left and right speakers accurately.
The Holographic Image
Holographic Image
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