NAD T 747 Owner's Manual - page 25
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 “S” (Small),
“Large” and “Off”, but note that physical size may be irrelevant.
• A “S” (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 “Off” 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 “Off”.
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 747’s 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 [ ] and then [
] keys. Set “Front”, “Center”, “Surround”
and “Back” to “Large”, “Small” (Small 60 Hz up to Small 150 Hz) or “Off” as your
subsystem’s speakers require.
Set “Subwoofer” to “On” or “Off”, selecting “On” only if you have a subwoofer
connected to the SUBW output jack. If the “Subwoofer” is set to “Off”, “Front”
speaker will automatically be set to “Large”.
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 747 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.
OPERATION
USING THE T 747 – SETUP MENU
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