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Linear Acoustic upMAX 2251 User Guide
Note that the two channel material is simply input to the
channel signal is available at the output. Either of the Commercial or Music presets
can be chosen, and are explained in detail at the end of this chapter.
A similar situation can arrise when the Dolby E system is in use, and can actually
help to automate the process of turning the upmixing process on and off with no user
intervention. The Status Port of a DP572 Dolby E Decoder provides a control signal
that is logic high (1) when the DP572 is decoding Dolby E material, and is logic low
(0) when two channel PCM audio is being passed through. By connecting the DP572
Status Port to the upMAX 2251 GPI input (A or B), the upmixing process will auto-
matically be turned on and off, and audio will be silently crossfaded between the two
modes. Figure 3-2 shows how this can be easily accomplished.
Dolby E Decoder
Dolby E
Main
or
Input
PCM
Vref
Status
(Pin 1,9)
Figure 3-2
The result is a clean, consistent 5.1 channel program that is discrete when Dolby E
is present and is upmixed when PCM is present, but with no audible change apparent
to listeners or viewers. Note that while the upMAX 2251 AES Reference input is
driven from the PCM Delay Output of the DP572 for the sake of clarity in Figure 3-
2, this is a perfectly acceptable approach to use in practice.
DP572
1/2
3/4
5/6
X
7/8
Delay
Out
MAX 2251
with Dolby DP572 Dolby E Decoder
UP
Linear Acoustic
MAX 2251
UP
Main Out
Main Input
Lf/Rf
Lt/Rt
Mix Input
Main Out
C/LFE
C/LFE
Mix Input
Main Out
Ls/Rs
Ls/Rs
Mix Input
Lf/Rf
Aux Out
Lt/Rt
AES REF
GPI A
IN
(Pin 2, 15)
15
Applications
MAX 2251 and a 5.1
UP
5.1 Channel
Main Output
Two-Channel
Utility Output
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