Phono stage hiss - Measurements

[Confused]

Interesting stuff.

Indeed, the 1 kHz tone graphs do not look anything like what I would expect from a 1 kHz tone.  For the record, it does sound like a 1 kHz tome when you listen to it.

I assume that is with the sub-sonic filter off, I think this shows you should have it on.  If it is with it on I think you have a TT rumble problem.  I say problem but I expect lots of us might do with vinyl setups, they are just so rarely measured we have no idea.

Looking at the Audacity plots I know exactly what you mean, however, I can confirm that these measurements were taken with the RIAA 1976 curve, which includes a subsonic filter by default.

Frankly, the Audacity plots are not very good, I will certainly be interested in seeing how things look if Mathieu Pernot runs these through his test gear.

As an aside, if I hover the curser over the actual plot in Audacity, it shows a peak of - 7.3 dB at 1003 Hz, this is not clear from viewing the graph itself.  I would like to find some better software for performing the analysis, I am sure there would be a few issues you could discover and potentially mitigate with measurements like this.  Subjectively, listening to the test tone you would say there is zero output from 1 to 100 Hz, but that is not what the measurements say.  It is interesting stuff.

EDIT:  I tried listening back to the 1 kHz recording via headphones.  Yes, it still sounds like a 1 kHz test tone, but on headphones you can clearly hear some vinyl surface noise, and a very, very, quiet, vey subtle, thump sound.  Ah the joys of vinyl "character".  I am not sure if the subtle thump thing is on the test record or my TT, although I suspect it sounds more like something on the record.  Something for further investigation another time …..