VT RTA-168A/B Manual Rev. 1.5
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Polarity: Speaker, Microphone, Amplifier Polarity Tester with Crest Factor Check
A polarity test signal will be generated by pressing the start button of the Signal Generator.
Point the microphone close to the center of the speaker under test along its axis, and observe
the polarity of the captured pulse in the oscilloscope window. If the pulse goes positive
initially, then the polarity of the speaker under test is positive, and vice versa.
Positive Negative
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THD: THD,THD+N,SNR,SINAD,Noise Level, ENOB (Avg. 10 )
A 1 kHz (to be precise, a frequency very close to 1 kHz) sine wave will be generated by
pressing the start button of the Signal Generator. The sine wave will be injected into the DUT
(Device Under Test), and the response of the DUT will be captured and analyzed by the
Oscilloscope and Spectrum Analyzer. All the above parameters of the DUT will be measured
and displayed. This panel setting should be used only if the same sound card is used for
signal input and output.
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THDcd: THD,THD+N,SNR,SINAD,Noise Level, ENOB (Avg. 10 )
A 1 kHz sine wave will be generated by pressing the start button of the Signal Generator. The
sine wave will be injected into the DUT (Device Under Test), and the response of the DUT
will be captured and analyzed by the Oscilloscope and Spectrum Analyzer. All the above
parameters of the DUT will be measured and displayed. This panel setting should be used if
different sound cards are used for signal input and output, such as the case of RTA-168. It
should also be used if the 1 kHz test tone is played from an audio CD or a memory stick.
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IMDsmp: IMD SMPTE (60 Hz + 7 kHz, 4:1) (Avg. 10)
A 60 Hz and a 7 kHz sine waves mixed at an amplitude ratio of 4:1 will be generated by
pressing the start button of the Signal Generator. The mixed signals will be injected into the
DUT (Device Under Test), and the response of the DUT will be captured and analyzed by the
Oscilloscope and Spectrum Analyzer. The SMPTE IMD value of the DUT will be measured
and displayed.
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IMDdin: IMD DIN (250 Hz + 8 kHz, 4:1) (Avg. 10)
A 250 Hz and a 8 kHz sine waves mixed at an amplitude ratio of 4:1 will be generated by
pressing the start button of the Signal Generator. The mixed signal will be injected into the
DUT (Device Under Test), and the response of the DUT will be captured and analyzed by the
Oscilloscope and Spectrum Analyzer. The DIN IMD value of the DUT will be measured and
displayed.
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IMDccif: IMD CCIF2 (19 kHz + 20 kHz, 1:1) (Avg. 10)
A 19 kHz and a 20 kHz sine waves mixed at an amplitude ratio of 1:1 will be generated by
pressing the start button of the Signal Generator. The mixed signal will be injected into the
DUT (Device Under Test), and the response of the DUT will be captured and analyzed by the
