360 Systems Image Server 2000 - Manual (Page 103)

Image Server 2000 Owner’s Manual Page 103
Alternate Calibration Procedure
If the calibration test clip titled zTONE is not found on the Image Server’s disk, it is still
possible to accurately calibrate the audio channels.
1. Position the jumper block J5 and J6 for Channel 1 output to obtain a digital output.
2. Using the On-Screen graphic user interface, place server Channel 1 in the E-E
mode, so that an input signal will appear at its output.
3. Use the audio generator to apply a 1 KHz sine wave at a level of +4 dBu to analog
audio Input 1-L.
4. While observing the digital output level of audio Channel 1-L, adjust input gain trim
pot RV2 until a level of –20 dBFS is obtained. (+4 dBu is 20 dB below full scale,
which is +24 dBu; therefore it reads 20 dB below full scale or Fs.)
5. Repeat steps 2 through 4 for analog audio Input 1-R, while adjusting input gain trim
pot RV1.
The server’s input gain is now calibrated. It remains to calibrate each analog output for unity
gain using the following procedure:
6. Position all audio output jumper blocks to obtain analog outputs.
7. Using the graphic user interface, verify that server Channel 1 is in E-E mode, so that
an input signal will appear at its output.
8. Apply a 1 KHz sine wave at a level of +4 dBu to analog audio Input 1-L.
9. While observing the output level of audio Channel 1-L, adjust output gain trim pot
RV4 until a level of +4 dBu is obtained.
10. While observing the output level of audio Channel 1-R, adjust output gain trim pot
RV3 until a level of +4 dBu is obtained.
11. Make a 1-minute clip of the 1 KHz sine wave at a level of +4.00 dBu. Save this clip
for future use in calibrating the server.
12. Play this clip from Channel 2 and repeat steps 9 and 10 to adjust the gain of the left
and right outputs.
13. Play the clip created in step 11 from Channel 3 and repeat steps 9 and 10 to adjust
the gain of the left and right outputs.
The server’s output gains are now calibrated, and the entire sequence of the preceding steps
have established a gain of unity through the server.
Another method is to use digital input with a digital sine wave of –20dBFS to calibrate analog
outputs 1 & 2 and create the reference clip.