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6.4c
B-Chain alignment is performed on output
channels individually. You can use the function
keys as an aid in channel selection or use the
MUTE/ON buttons illustrated in 6.3a. Because the
channels are linked, pressing a function key or
button selects and un-mutes (turns on) that channel
while muting (turns off) all other output channels.
6.5 Now select each output channel in succession, confirm that the noise sound is coming from the
correct loudspeaker, and adjust the channel's equalization and level. Start by adjusting the equipment
between the System Outputs of the DFP-D3000 and the loudspeakers to achieve about 85 dBC SPL
in each screen loudspeaker, measured individually (82 dBC for each of the two surround channels).
This equipment may include crossovers and power amplifiers from a number of manufacturers so
specific instructions cannot be given here. Sony recommends using several measurement micro-
phones and a microphone multiplexer to drive your RTA, but each engineer will have their own
preferred measurement techniques.
6.6 Adjust the graphic equalizer to achieve the "X" curve of SMPTE 202M, or other frequency response
that has been established for your theatre. Do this for each loudspeaker attached to an output channel,
except the subwoofer. Setting the graphic equalizer for best results requires skill and experience, but
a few general points can be made. Make small adjustments and let the RTA display settle down after
each adjustment. Cutting EQ is always better than boosting EQ. Adjacent bands with boost and cut
differences of more than 3dB indicates problems that aren't appropriate for EQ to correct; try to end
up with a smooth equalizer setting using as little EQ as possible and no more than a few dB differ-
ence between adjacent bands. Use even less EQ on the surround loudspeakers. The screen speakers
should all have the same EQ settings (if they are the same cabinet type); if they aren't very close,
there may be problems that EQ should not be used to address. Don't boost low bands in an attempt to
extend the low frequency response; that is mainly determined by the cabinet design. Remember that
you can only adjust for the sound that comes directly from the loudspeakers to the measurement
microphone; you cannot do much about the sound that is influenced by the auditorium acoustics or
resonances and you should avoid the temptation to try to do so. If you see wide variations when you
move your microphones around in the auditorium, position them closer to the front so as to measure
more sound direct from the loudspeakers and have less influence from the sound that has bounced
around the auditorium (which you can't affect with EQ).
6.7 When all loudspeakers except the subwoofer have been EQ'd, make a wideband adjustment in the
equipment between the DFP-D3000 and each of the loudspeakers (such as with a power amplifier
gain control) to achieve 85 dBC SPL from each screen loudspeaker. This is a wideband sound
pressure measurement; at this point, the individual bands of your RTA will each be at about 70 dB
SPL. The left and right surround cabinet groups should each be set for 82 dBC wideband. It is better
to achieve this result with an adjustment of amplifier gain than by using a Channel Level Trim, and
when using a Channel Level Trim, it is better to preserve full headroom by using attenuation (cut, or
_dB) instead of gain (boost, or +dB).
DFP-3000
Function Key
Channel
F1
Left
F2
Left Center
F3
Center
F4
Right Center
F5
Right
F6
Subwoofer, (LFE)
F7
Left Surround
F8
Right Surround
6-3
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