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Re: John, you were sucker-punched, then piled on, by the Usual Suspects.

Steve, please ask someone else about the Sound Technology 1700B. Perhaps they can explain its operation to you. I have used the unit for the last 27 years. I have some idea of its operational capabilities, but apparently you haven't ever used an analyzer of this type. I am optimistic that you actually want answers to your questionds, but sometimes I wonder.
In any case, the distortion output of the Sound Technology is set for -30dbV for -80dB harmonic distortion. This is factory set. This output also reads -80dB on the distortion scale. Therefore -45dB would be 15db lower than -80dB, which is -95dB. This is the distortion residual of the ST1700B. The harmonics are present at a somewhat lower level on my graphs. They can only be seen and measured with a spectrum analyzer which separates the spectrum into its harmonics. The spectrum analyzer also removes extra noise added by the relatively large bandwidth.
This can be done in two ways: One approach is by using a narrow resolution bandwith of 10-30 Hz or so. This will lower the noise so that the harmonics can be seen.
A second way is to use signal averaging with an FFT analyzer. In this case I use 100 or more measurements and add them together electronically. The harmonics add directly, but the noise adds randomly, so it doesn't increase as fast as the signal. This also separates the distortion residual from the noise.
The absolute magnitude that Steve Eddy is concerned about is really not very important, because I do RELATIVE testing between different cables, and this does not require exact calibration of the distortion harmonics, just a RELATIVE equivalance in the measurement of the distortion harmonics of the cables. I hope that any of you interested in this test, now have some idea of how it is conducted.

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