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7700 MultiFrame Manual
7720DAC-A4 AES to Analog Audio Converter
4.2.
CHANNEL STATUS INDICATOR LEDS
On the card edge, each channel has two indicator LEDs: one red (bottom side of the card) and one green
(top side of the card). The group of LEDs closest to the toggle switch represents CHANNEL 1 (left channel
in AES input 1), followed by LEDs for CHANNEL 2, 3, and 4. The table below summarizes their meaning:
Green LED
Red LED
Off
Flickering
Flashing
GREEN
And flickering
Solid
Flashing
GREEN
Solid
GREEN
4.3.
DOT-MATRIX DISPLAY
Additional signal and status monitoring is provided via the 4-digit dot-matrix display located on the card
edge. The rotary switch position determines what is displayed on the dot matrix display. When it is set to
position 0, the input audio peak levels are shown using bar graphs on the display. Pressing the toggle
switch up when the rotary switch is at position 0 will orient the display vertically; pressing the toggle switch
down will orient the display horizontally. When it is set to 1 to 4 the peak level corresponding to 0 dBFS
input for each of the channels will be displayed, and can be set using the toggle switch (see section 5.1.1).
When the rotary switch is at position 5, the display will show lock status and the detected sample rates for
each AES input (see section 4.3.2). When the rotary switch is at position 6, the display will show the
numerical values of peak levels found in each input channel (see section 4.3.3).
4.3.1. Audio Level Bar Graphs
When the rotary switch is set to position 0, each section of the dot matrix display shows a bar graph
representation of the peak level for one of the audio channels. Channel 1 is shown on the left (top)
section and channel 4 is shown on the right (bottom) section. Each section of the display is comprised of
a 5 x 5 array of dots. Diagonal rows of dots represent one of 9 different signal peak levels as shown
below.
Level 1
Level 2
The signal levels shown in Table 2 are nominally in dBFS units. Table 2 also shows the peak levels in dBu
when the peak level is set so that 24 dBu = 0 dBFS (see section 5.1.1). The ballistics of the bar graph
7720DAC-A4-6
Meaning
Solid
Input AES is not recognized:
RED
There is no input, or cable length is too long, or sample rate is outside of 42-50
kHz range
The analog outputs will be muted
Input AES is between 42-50 kHz but the signal is getting too weak to recognize
The analog output audio will show a varying degree of distortion
RED
Input AES is between 42-50 kHz but it is outside of both 44.1 kHz (±100 ppm)
RED
and 48 kHz (±100 ppm) specs
The analog output audio should be intelligible but will show a varying degree of
distortion
Off
valid AES input
Table 1: Card Edge CHANNEL Status LEDs
Level 3
Level 4
Figure 4: Bar Graph Displays
Level 5
Level 6
Revision 1.2
Level 7
Level 8
Level 9
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