Speaker Configuration; Speaker Levels - NAD T 748 Owner's Manual

OPERATION
USING THE T 748 – SETUP MENU

SPEAKER CONFIGURATION

Every surround-sound system requires "bass-management" to direct low-
frequency content from any or all channels to the speakers best able to
reproduce it. For this function to operate correctly, it is important that you
correctly identify your speakers' capabilities. We use the terms "Small" and
"Large" (and "Off") but note that physical size may be irrelevant.
• A "Small" speaker is any model, regardless of physical size, that lacks
significant deep-bass response, that is, below about 150 Hz.
• A "Large" speaker is any full-range model; that is, one with deep-bass
response
• An "None" speaker is one that is not present in your system. For example,
you might not have any surround-back speakers installed; in that case,
you would set the "Back" setup item to "None".
The Speaker Configuration is "global"; that is, it remains in force with all
inputs and in all listening modes. However, speaker settings are part of the
T 748's A/V Preset system. Consequently, multiple speaker settings can be
stored for easy recall as different types of recordings or listening modes
require.
Speaker Configuration can be managed and adjusted by pressing a
combination of [ S ] and then [ D/F ] keys. Set "Front", "Center", "Surround"
and "Back" to "Large", "Small" ("Small 60Hz" up to "Small 150Hz") or "None" as
your subsystem's speakers require.
Set "Subwoofer" to "On" or "Off, " selecting "On" only if you have a subwoofer
connected to the T 748's SUBW output jack. If the "Subwoofer" is set to "Off",
"Front" speaker will automatically be set to "Large".
ENHANCED BASS
When the subwoofer is set to "On" and "Front" is set to "Large", Enhanced
Bass becomes available. Normally, with speakers set to "Large" the
subwoofer is not active. The Enhanced Bass option allows full range
operation of the speakers with the additional bass contribution of the
subwoofer. This feature is particularly useful when one wants to experience
maximum bass output. Please note that due to acoustic cancellation
effects, the bass response may be uneven when using this setting
You can set Subwoofer to "On" even with "Large" front speakers, in which
case bass content from any channels set to "Small" will be routed to both
the subwoofer and to the front speakers; LFE-channel signal will pass only
to the sub. In most subwoofer-equipped systems, setting front speakers to
"Small" is usually the better option.
All the speakers' low frequency content can be directly adjusted within the
range 60Hz to 150Hz.
NOTE
The configurations set forth at "Speaker Setup" are carried over
whenever it is enabled during A/V Presets setting. Please see also the
section "AV Presets Setup" for reference.
20

SPEAKER LEVELS

Adjusting the relative balance of your system's loudspeakers ensures that
surround-sound recordings, whether music or film, will present the balance
of effects, music, and dialog that the artists intended. Additionally, if your
system incorporates a subwoofer, it establishes a correct relationship
between the volume of the subwoofer and the other speakers, and thus of
low-frequencies (bass) to other sonic elements.
USING AN SPL METER
It is quite practical to perform the T 748 level setup routines "by ear, " and
careful work will produce acceptably accurate results. However, the use
of an inexpensive sound-pressure level (SPL) meter, such as Radio Shack
part number 33-2050, makes this task easier, more accurate and more
repeatable. Ownership of such a meter could prove a valuable audio tool.
The SPL meter should be placed at the primary listening position, at
approximately the height of the seated listener's head. A tripod is helpful
but with a little duct tape almost anything - a pole lamp, music-stand,
or ladder-backed chair, for example - can do as well. Just be sure that no
large acoustically reflective surfaces obstruct or are near the microphone
element.
Orient the meter with its microphone (usually at one end) pointing straight
up toward the ceiling (not toward the speakers) and ensure that "C"
weighting scale is selected. Set the meter to display 75 dB SPL. On Radio
Shack meters, this necessitates either setting the meter to its 80 dB range
and taking your readings at the -5 point or selecting the 70 dB range and
reading at the +5 point.
SETTING SPEAKER LEVELS AT TEST MODE
While at "Speaker Levels" menu, press the AVR 4 remote's [TEST] key
activating the T 748's Speaker Levels balancing test signal. You will hear a
"surf" sound as the test mode cycles through the speakers ("test" appears
to the right side of the current speaker), beginning with the Front Left. If
you do not hear the test signal, check your speaker connections or your
"Speaker Configuration" OSD menu settings.
Use the remote's [ D/F ] keys to adjust the loudness of the noise output
from the currently playing channel to the required level (it's usually simplest
to begin with the Front Left). As the test signal cycles around the speakers,
the OSD will highlight the currently playing channel. The "level offset"
reading on the right will change by 1 dB increments; ±12 dB adjustment is
available. Press [ENTER] to adjust the next speaker or for the Test mode to
continue on with the other speakers in sequence.
NOTE
If you are balancing levels "by ear", choose one speaker - usually the
center - as a reference and adjust each of the others in turn to "sound as
loud" as the reference. Be sure that you remain in the primary listening
position while balancing all channels.