2
A note about Dolby’s products: The SEU4 and SDU4 are 1U high, 19" rack mount professional
units. Both use XLR type connectors with balanced line levels adjustable from -10 to +8 dBr
(0dBr=0.775 Vrms). Pin 2 is “hot.” For unbalanced connections, pin 1 is tied to pin 3 for proper
operation.
3.
Mixing console.
Mixing will be performed in four channels, so a four-buss output structure is needed, as shown
in Figure 1. A conventional stereo console with sufficient subgrouping and auxiliary sends
may be used. Automation is not required, but may be beneficial for fine-tuning special effects.
Four channel pan pots are also desirable for certain effects, although even basic pair-wise left-
right and center-surround panning facilities may be adequate for some productions.
The SDU4 mode and level controls simplify connection directly to monitor amplifiers. Figure1
shows typical signal flow.
Program meters (with peak and average weighting) are recommended to read the four encoder
input signals and two encoder output signals.
SEU4
Encoder
Mastering
Machine
Audio
Sources
SDU4
Decoder
L
S
R
C
Amps
Speakers
S
Fig. 1 Mixing in Dolby Surround from Multitrack Elements
4.
Speakers and amplifiers.
Three speakers are needed across the front to produce the left, center and right channels.
Ideally, all three will be the same model for best acoustic matching. Unfortunately, it may not
be possible to use the same speaker in the center due to space restrictions. In such cases, finding
one that blends well sonically is important. Using a smaller model from the same product line
as the left and right speakers is recommended. Use of a magnetically shielded speaker is
necessary whenever that speaker needs to be positioned near a video monitor.
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