Orban Optimod-FM 8300 Operating Manual page 200

4-10
MAINTENANCE
D) Inject the Analog Input XLR connector with a level of 0 dBu with the oscillator
set to 100 Hz.
This is 20 dB below the clip level, which allows headroom for pre-
emphasis. (75s pre-emphasis will cause 17 dB of boost at 15 kHz.)
E) Connect the audio analyzer to the 8300's Left Analog Output XLR connector.
F) Verify a level of 0 dBu ±1 dB. Use this level as the reference level.
G) Verify that frequency response at 50 Hz, 100 Hz, 400 Hz, 5 kHz, and 15 kHz is
within ±0.1 dB of the reference level.
This procedure tests the analog input circuitry, the A/D converter, the
DSP, the DAC, and the analog output circuitry.
H) Repeat steps (C) through (G) for the right channel.
5. Check distortion performance of Analog I/O.
A) Verify 8300 software controls are set to their default settings. (Refer to page
4-7.)
B) Be sure you are still in B
C) Connect a THD analyzer to the Left Analog Output XLR connector. Set the
THD analyzer's bandwidth to 22 kHz.
D) Connect the oscillator to the Left Analog Input XLR connector.
E) For each frequency used to measure THD, adjust the output level of the oscil-
lator to make the C
You will have to reduce the output level of the oscillator at higher fre-
quencies to compensate for the pre-emphasis boost in the 8300.
F) Measure the THD+N at the frequency levels listed below.
Frequency
50 Hz
100 Hz
400 Hz
1 kHz
2.5 kHz
5 kHz
7.5 kHz
10 kHz
15 kHz
G) Repeat the above measurements for the right channel. Connect the oscillator
to the right analog input and the distortion analyzer to the right analog out-
put.
H) Disconnect the oscillator and THD analyzer from the 8300.
mode [see step (3.F)].
YPASS
meter on the 8300 read 100.
OMP
THD+N Typical
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
0.015%
ORBAN MODEL 8300
THD+N Maximum
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%
0.03%