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display follow the AES/EBU guidelines and have the attack time constant set to 0 seconds, and the decay
time constant set to 1.5 seconds / 20 dB.
4.3.2. Detected Sample Rate Display
When the rotary switch is set to 5, the display will show lock status and the detected sample rates for each
AES input. The left (or top) two digits will show the rate of AES 1, and the right (or bottom) two digits will
show the rate of AES 2. Table 3 summarizes the meaning of the display content:
Display
Meaning
input AES is not recognized:
XX
the analog output audio will be muted
Input sample rate is between 42 - 46 kHz and it is either outside of 44.1 kHz (±100
44
ppm) spec or the signal is getting too weak to recognize. The analog output audio
(flashing)
should be intelligible but will show a varying degree of distortion
Input is between 46 - 50 kHz and it is either outside of 48 kHz (±100 ppm) spec or the
48
signal is getting too weak to recognize. The analog output audio should be intelligible
(flashing)
but will show a varying degree of distortion
44
valid 44.1 kHz (±100 ppm) input
48
valid 48 kHz (±100 ppm) input
4.3.3. Detected Numerical Peak DBFS Levels Display
When the rotary switch is set to 6, the display will show the numerical values of peak levels found in each
input channel. By using the toggle switch, the display can be changed to display any 1 of the 4 input audio
channels. Each time, the display will show the channel number, followed by the "-" (minus) sign, and a 2
digit number representing the detected peak level in dBFS.
E.g.: if the display reads "2-13", then it means that channel 2 (the right channel in AES 1) had peak levels
reaching -13 dBFS.
If the input doesn't lock properly, the peaks will read as "??".
This measurement is updated about once a second and is accurate to within 1 dB from 0 down to
-80 dBFS. Below –80 dBFS, the displayed value is only approximate.
Bar Graph Level
Level 1
Level 2
Level 3
Level 4
Level 5
Level 6
Level 7
Level 8
Level 9
Table 2: Bar Graph Levels
there is no input, or
cable length is too long, or
sample rate is outside of 42 - 50 kHz range
Table 3: Sample Rate Display
Revision 1.2
7720DAC-A4 AES to Analog Audio Converter
dBFS
dBu
-60
-36
-36
-12
-30
-6
-24
0
-21
3
-18
6
-15
9
-12
12
-6
18
7700 MultiFrame Manual
7720DAC-A4-7
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