Adcom GTP-600 - Manual (Page 17)

4) CONCERT HALL replicates an indoor performance space that is still relatively large. Front channel
frequency response is fiat for maximum musical clarity while the diminishing multiple rear channel delays
first seen in Cinema mode enhance the sense of spaciousness.
Left & right front output; Stereo
Center channel output: No
Initial delay setting: 50 milliseconds
Additional delay choices: 75 & 30 milliseconds
5) NIGHTCLUB synthesizes a smaller and more intimate soundfield ideal for many types of jazz and popular
music. NIGHTCLUB is also a good choice for playback of classic movies with mono soundtracks.
Left & right front output: Narrow matrix
Center channel output: No
Initial delay setting: 15 milliseconds
Additional delay choices: 30 & 20 milliseconds
6) 5 CHANNEL STEREO sends a mono (L + R) signal to the center channel speaker. When no delay is
chosen (the default choice,) left front information goes to the left rear speaker and right front data to the
right rear speaker. If delay is chosen, the left and right rear outputs are summed to mono and then sent
through the delay line.
Left & right front output: Stereo
Center channel output: Yes (L+R)
Initial delay setting: No delay (stereo rear)
Additional delay choices; 100, 75, 50, 30, 20 & 15 milliseconds (mono rear)
7) 2 CHANNEL STEREO (Bypass); This is the “what’s on the disc is what you get” mode; No processing, no
delay and no center channel. Obviously, this mode is for the serious listener who wants the maximum in
stereo music reproduction. Here, the full audible benefits of ADCOM's proprietary linear gain line amplifier
stages and precision Roederstein 1% metal film resistors are obvious.
Left & right front output; Stereo
Center channel output; No
Initial delay setting; None
Additional delay choices; None
B) Choosing the proper rear channel delay setting
Rear channel delay (available in Cinema, Dolby Pro Logic, Stadium, Concert Hall. Nightclub and 5 channel
stereo operating modes) is a technique that has been used in consumer audio equipment since the early
70s. Sometimes confused with the various quadraphonic technologies briefly popular two decades ago,
time delay is a much more defined and exact process.
Briefly stated, time delay takes information from the rear (or surround) output of the decoder, “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 Cinema and Dolby Surround playback. Here, proper time delay prevents us from hearing front channel
information, particularly dialog, from the rear speakers. Based on a psychoacoustic effect called “masking,"
this technique preserves the proper directional clues intended by the source’s producer. For this reason,
both Cinema and Dolby Pro Logic modes intentionally limit rear channel time delay to very small amounts.
If you delay rear channel information for a longer period, you 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 as an integral part of a coherent soundfield. Of course, this is exactly what happens in
a large environment like a stadium. That's why ADCOM has included longer delay times in the GTP-600; the
additional aural flexibility makes reproduction of some audio/video events more realistic.
Somewhere in the middle of this range of effects, time delay has other interesting and useful applications. For
example, longer delay times often give the impression that we are in a large room — the longer the delay, the
larger the apparent space is. If we’re not particularly concerned with the “masking effect,” we can experiment.
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