Adcom GSP-560 - Bass, Subwoofer, and Amplification Options

CONCERT HALL, recreates a fairly big and acoustically reverberant environment well suited for playback of full
orchestral works and other music that is usually performed in large indoor spaces
Rear channel delay choices 40 and 30 milliseconds.
NIGHTCLUB, synthesizes a smaller and more intimate soundfield ideal for many types of jazz and popular music
Rear channel delay choices' 20 and 15 milliseconds
5 CHANNEL MATRIX is ideal for mono sources — the soundtracks of older videotapes, for example — and
creates a dimensionally enhanced, diffuse soundfield for increased enjoyment
No rear channel delay is available in this mode
5 CHANNEL STEREO differs from the MATRIX mode in that no dimensional enhancement is performed 5
CHANNEL STEREO simply sends a mono (L + R) signal to the center channel speaker, Left Front information to
the Left Rear speaker and Right Front data to the Right Rear.
No rear channel delay is available in this mode
b) Choosing the proper rear channel delay setting
Rear channel delay (available only in Dolby Pro Logic, Concert Hall and Nightclub modes) is a technique that
has been used in consumer audio equipment since the early 70s Sometimes confused with the various
quadraphonic technologies popular in the mid 70s, time delay is a much more defined and exact process
Time delay takes front channel information, “stores” it for a brief period of time (usually less than one tenth of a
second), and then sends it to the rear speakers While a useful technique to enhance apparent spaciousness and
ambience, time delay also serves a specific purpose in Dolby Surround playback it prevents front channel
information (usually dialog) from “leaking" into the rear speakers The reasons for this benefit are complex and
based on a psychoacoustic effect called “masking ” Dolby Surround decoding limits time delay to a maximum
of 30 millliseconds in order to optimize the intelligibility of the dialog information in a video soundtrack
If you delay rear channel information longer than 30 milliseconds, you grandually lose the “masking” effect and
become aware of a growing discontinuity between front and rear outputs Eventually, you’ll perceive the rear
channel output as a discrete echo rather than as an integral part of a coherent soundfield
Somewhere in the middle of this range of effects, time delay has some interesting and useful applications For
example, longer delay times often give us the impression that we are in a larger room—the longer the delay, the
larger the apparent space is If we’re not particularly concerned about the “masking effect” necessary for proper
Dolby Surround processing, we can experiement
THE PRACTICAL APPLICATION OF THIS INFORMATION IS SIMPLE: IF YOU WANT TO CREATE A
SMALLER ACOUSTICAL ENVIRONMENT, CHOOSE A SHORT DELAY TIME. IF YOU WANT TO BETTER
APPROXIMATE THE ACOUSTICS OF A LARGER SPACE, CHOOSE A LONGER DELAY TIME. That’s why,
for example, the Concert Hall mode allows you to choose either 40 or 30 milliseconds delay arid the Nightclub
position restricts your choices to 20 or 15 milliseconds
19) BASS BOOST AND SUBWOOFER USE: INCREASING THE THUNDER
The “Bass EQ” circuit, activated by either thefront panel or remote controller buttons (©and ©respectively) increase
basscontent in Left Front and RightFront outputs by approximately8dBat80 Hz This adds substantial lowfrequency
energy or “punch” to music or a video soundtrack.
For even more bass output capability, the GSP-560 has a separate “Subwoofer” line output ©for connection to a
dedicated separate amplifier/subwoofer combination or a self-contained powered subwoofer
When using this output, make sure to adjust the “Subwoofer Crossover Switch” © to the position best suited to
the subwoofer you are using. This switch has three positions “150”, “60” and “flat”. In the “150” position, the
subwoofer output isfiltered so thatthere is little audio information above 150 Hz The “60” position screens information
above 60 Hz while the “flat” position sends an unfiltered, broadband signal to the subwoofer output
Consult your subwoofer’s owner’s manual for specific recommendations
20) CUSTOM INSTALLATIONS: USING MORE POWERFUL AMPLIFIERS WITH THE GSP-560
The GSP-560’s center and rear line outputs (© through ©) provide an additional measure of flexibility While most
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