Lexicon CORE2, Руководство по обслуживанию

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Lexicon Studio Core2 Service Manual
4-12
DBX THD+N Tests:
Analog In To Digital Out DBX THD+N Test:
These tests check the THD+N characteristics of the analog input to digital output path with the “dbx”
saturation circuit enabled (jumpers at W5-W8 on the Core2 Main board).
1. Apply a 1kHz signal @ +5dBv from the Analog Low Distortion Oscillator to the Analog Input marked #1
on the Core2 Connector Box.
2. Connect the digital output marked S/PDIF of the Core2 Connector Box to the Digital Distortion Analyzer
set to measure THD+N.
3. Open the LexPanel by double clicking on the Lexicon Studio Icon.
4. Click on the Core2 tab to bring it forward. In the Routing area, activate the Analog Inputs and S/PDIF
Out buttons by clicking on them. If Optical is enabled (checked), disable it.
5. To activate your Routing selections, click on the Apply button, if it is flashing. There is no need to click
the Apply button if it is not flashing.
6. Click on the Clock Source tab to bring it forward. In the Clock Source menu select Internal and set the
Sample Rate to 44100.
7. Click on the Punch tab to bring it forward. To enable your Input Source and Output Destinations
selected from the Core2 tab, make sure the enable punch check-box is selected (it will have a check in
the box if enabled).
8. Hold the CTRL key down on the computer keypad, then in the Sources menu Select all A/D inputs 1-4.
9. Hold the CTRL key down and select S/PDIF Out L and S/PDIF Out R in the Destinations menu.
10. Verify the digital output is between 0.25% and 3.00% (1.35% typical ). Refer to the graph at the end of
this section for DBX characteristics.
11. To test the remaining Inputs, move the input cable from the #1 analog input to each of the remaining
inputs 2-4 and test for the audio spec as described above.
12. The above test needs to be repeated for the S/PDIF Optical output connection of the Core2.
13. Disconnect the Coax S/PDIF Output.
14. Using optical cable connect the Optical Output on the back of the Core2 card to the Digital Distortion
Analyzer.
15. In the Routing area, activate the Optical S/PDIF Out by checking the Optical box.
16. Move the Audio Input cable back to the analog #1.
17. Repeat steps 10 and 11 and check for THD+N specification.
DBX Characteristics
-0
8
1
2
3
4
5
6
7
%
T
H
D
+
N
-0 +8 +1 +2 +3 +4 +5 +6 +7
Input Amplitude dBV
Upper Trace
"dbx" Enabled
(W5-W8)
Lower Trace
"dbx" Disabled
(W1-W4)