NAD T 751751 Owner's Manual page 20

GB
Dolby Digital uses a dedicated Low Frequency
Effects (LFE) channel. If a subwoofer has been
selected, the LFE channel will be fed to the sub-
woofer output.
Channel Delays:
For the best surround sound performance it is
important that sound from all speakers reach the lis-
tener's ears at the same time. Because the sur-
round/rear speakers are usually closer to the listener
than the front speakers, there is tendency for the ear
to localise sounds to the rear, because the ear takes
most notice of the sounds that arrive at the head first.
Similarly, the center speaker is often closer to the lis-
tener than the front left and right speakers. To com-
pensate for this, the T 751 can slightly delay the
audio sent to the center and rear (closer) speakers. In
this way, when playing Dolby Digital or Dolby Pro
logic soundtracks, the sound from all speakers
arrives uniformly at the listening position as intended
by the film's producer.
Each millisecond corresponds approximately with 1
foot or 30.5 centimeters.
NOTE:
The channel delay option is not available in DTS
surround mode.
To set the center channel delay time,
• Call up the SETUP menu of the On Screen
Display (Fig. 7).
• Select the CHANNEL DELAYS menu (Fig. 10).
• Choose CENTER and select the desired delay
time (1, 2, 3, 4 or 5ms).
FRONT
LEFT
REAR
LEFT
Measure the distance from the listening position to
the center speaker (dC) and to one of the front
speakers (dFL or dFR). Subtract the center channel
distance from the front L or R channel distance. For
example, if the front speakers are 12 feet (3.7 m)
from the listening position and the center speaker is
10 feet (3.0 m), the difference is 2 feet (0.6 m). For
this example the center channel delay is set to 2 mil-
liseconds or ms.
The T 751 can delay the center channel output up
to 5 milliseconds and thus compensates for center
NAD
20
FRONT
CENTER
RIGHT
dC
dFL dFR
LISTENING
POSITION
dFS dRS
REAR
RIGHT
channel speakers that are up to 5 feet (1.5 m) closer
to the listening position than the front left and right
speakers.
NOTES:
In rare system setups, the center channel speaker
is actually further away than the front left and right
speakers. In these cases, set the center channel
delay to 0mS. The center channel delay time adjust-
ment is only available in Dolby Digital surround mode.
To set the rear channel delay time,
• Use the 3 or 4 cursor button (No. 7) to highlight
the REAR.
• Scroll the preset delay time options by 1 and 2
cursor buttons.
Measure the distance from the listening position to
either the left or right rear speaker (dLS or dRS).
Subtract the rear speaker distance from the front
speaker distance (dFL or dFR). The resulting dis-
tance is equivalent to the delay in milliseconds for the
rear delay setting. For example, if your rear speaker
distance is 6 feet (1.8 m) and the front distance is 12
feet (3.7 m), the correct rear channel delay setting is
6 milliseconds. Again, set the rear channel delay to
0mS if the rear channels are further from the listening
position than the front speakers.
In Dolby Digital surround mode, the rear channel
delay time can be set from 0ms to 15ms with 1ms
increments.
In Dolby Pro logic surround mode, the rear channel
delay time can be set from 15ms to 30ms and 1ms
per step. In DTS surround mode, the channel delay
time cannot be adjusted.
• When both delays have been entered, choose
"SAVE & EXIT" to save the settings and return to the
Main Menu.
Channel Balance:
The output levels of each of the speakers connect-
ed to the T 751 may need to be adjusted so that there
is an even balance of sound from all the speakers in
the system. If, for instance, the relative volume level
to the Left and Right speakers and the center speak-
er is set too low, most of dialogue may be difficult to
follow. If, on the other hand it is set too loud, the over-
all balance will sound unnatural.
To adjust the channel balance the T 751 is
equipped with a TEST button (No. 6) to help assess
the loudness levels of each speaker. Before adjusting
the channel balance level make sure the master vol-
ume is turned down to a normal listening level.
Pressing the TEST button engages the Test signal