SP395 SoundPro Audio Integrator
Form7492
Operation Manual
77
Distortion Meter Control Field Descriptions:
1.
Test Function –
Identifies Distortion Meter as the menu selection.
2.
Distortion Type –
Selects the type of distortion test either IMD or THD
3.
Test Frequency or Standard –
Selects the frequency of the THD+N distortion test.
Note:
the generator low distortion sine-wave test frequency must agree with this frequency.
Selects the SMPTE IMD test (7kHz/60Hz) or DIN IMD test (8kHz/250Hz).
4.
Input Select
– Selects either the right or left input for the distortion test.
5.
Distortion Meter Test Readout
– Indicates distortion test results in dB.
6.
Test Function Identification
– Test Indicator only – this field is not selectable.
7.
Distortion Meter Readout
– Digital value indicating % of distortion for test.
8.
Measurement Scale
– Fixed scale used to graphically indicate distortion %. Not
selectable or variable.
9.
Distortion Meter Indicator
– Arrow indicator that marks a distortion level on the visual
scale indicating % distortion.
10.
Generator On/Off
– Turns generator output on or off. Active for all distortion tests.
11.
Generator Output Level
– Indicates and provides level adjustment for the generator
output. Active for all distortion tests.
12.
Generator Waveform
– Selects generator output waveform. The waveform type should
be a sine-wave for the THD + N test. This field does not appear in the IMD test as a
special two tone test signal is generated and output by the generator.
13.
Generator Test Frequency
– Only shows on TDH+N test. Indicates the frequency output
of the generator. The frequency should match the frequency of the THD+N test selection.
How to use the THD+N Distortion Meter
1.
Set up the Output:
Connect the SP295 output to the input of the device to be measured.
Or use an external sine wave signal source at the correct frequency to match the distortion
test. Typically THD+N testing is performed at 1 kHz.
2.
Set up the Input:
Connect the output of the device being tested to the SP395’s left input.
Turn off the phantom power, set the input gain (auto-gain may be used), and select the
Left In for the input on the distortion test field.
3.
Frequency:
Select the desired distortion test frequency within the THD+N test screen,
typically 1 kHz.
Note - The distortion test frequency must match the
generator frequency.
4.
Generator On/Off & Level –
If using the SP395 generator, turn the generator on and
adjust the output level. Be sure to check and/or adjust the input gain on the SP395 to avoid
clipping distortion.
Note: Be sure you are using a sine-wave at the proper frequency.
5.
Read THD+N:
Read the distortion in %
