Thanks Hans, this is what I thought I saw. I'll have a look through my Picoscope measurements to see if they are any better. Otherwise, there is no use in trying to get a meaningful SNR measurement with either of these set-ups. A last option (if I want) is to change the head-amp to +30 or + 40dB, and see waht that brings. Otherwise, I can only use this set-up if I want to see if I can get rid of the 15-20 kHz junk (and the 50 Hz hum), once I know that this isn't aliasing I am looking at. My thoughts are that the turntable (which is direct drive) is generating noise, or that my tone-arm grounding leaves room for improvement. Having said that, the record's own groove noise is much higher than what is coming from the RIAA pre-amp / cart combo.
Previously I was using the Picoscope in a valve environment to trim phase-inverters and balance cathode currents on PP outputs to minimize 2nd harmonic distortion, for which it worked well, since the distortion levels are much higher than the noise floor.
Previously I was using the Picoscope in a valve environment to trim phase-inverters and balance cathode currents on PP outputs to minimize 2nd harmonic distortion, for which it worked well, since the distortion levels are much higher than the noise floor.
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