| Re: Turntable Cartridge Measurements [message #90655 is a reply to message #90654] |
Mon, 08 July 2019 19:40   |
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Wayne Parham
Messages: 18856
Registered: January 2001
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Illuminati (33rd Degree) |
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The sweeps (which are actually stepped sines) are of equal amplitude so if the reactive load on the cartridge and the RIAA equalization is accurate, then the output of at all frequencies will be equal amplitude.
I switched from oscilloscope view to spectrum view for this test. That made it easier to see the signal and its amplitude: As frequency rises, the position of the signal simply moves to the right on the graph.
There are a couple things I would have liked to have done differently. One is the horizontal (frequency) scale, which is linear and goes clear out to 24kHz. That's fine when doing high-frequency sweeps, but it would have been better for me to have switched to a view that limited the range to 1kHz, placing that at the far right of the chart for low-frequency sweeps. I'm not familiar with Daqarta yet, so I don't know how to do that or if it's even possible.
The other thing I would have liked to have done was to sample the screen captures more often, so I could capture all the signals. I had a screen capture program set to grab the Daqarta window every half-second, so it missed some of the signals. I still got a good representation of the behavior of the system though. Maybe next time I'll study the program more so I can capture all the frames, perhaps as an animated GIF.
Stepped sines from 1kHz to 10Hz:
Amplitude response looks pretty good and flat between 10Hz and 1kHz.
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