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Swept Tone 1kHz to 5kHz
post Feb 17 2012, 13:47
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The attached is a sweep tone I found that I recorded several years ago.

You can clearly see the added harmonics especially nearer the higher frequencies. I'm not sure that I can hear them but you can judge for yourselves
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Attached File  Sweep_1kHz_to_5kHz_at_44.1Khz_Sample_Rate.flac ( 1.75MB ) Number of downloads: 242
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post Feb 17 2012, 23:04
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This may be extending the original topic a little but the thread provides an opportunity to ask about something that has been a curiosity for some years. An LP entitled
Cardas Frequency Sweep and Burn-In Record
has some sweep tones to 30kHz, one starting at 30Hz, the other two at 1kHz.

I recorded them at 88.2kHz. While there is obvious intensity decrease starting between 14kHz and 15kHz, the signal is still very definite all the way to 30kHz. I have no clue how much of the decrease in signal level is due to my playback system and how much is what actually exists on the LP. I do know that if I generate a constant level sweep tone in a 96kHz space on one computer, play it analogue-out of one Audiophile 2496 and analogue-in to another on a different computer, there is little signal loss through the process, so this is not primarily a sound card artifact.

What is obvious in my recording of the sweep tones, but would be very difficult to detect in music (unless there is some kind of analysis software than can do so) is that substantial multiple harmonics exist, starting at low frequencies and extending to the highest frequencies. In spectral view the first five of these can be readily seen to reach the Nyquist limit at 44.1kHz (and to alias there, as would probably happen with any sigma-delta ADC). Such harmonics are not created by the playback and recording of generated sweep tones, as described in the previous paragraph. I have observed similar harmonics in lesser range sweep tones from other test LPs

Either these harmonics exist on the LP or they are generated by my playback system (which would almost certainly mean the cartridge, as I don't fine evidence of them in any other kind of tests not involving the cartridge). If they are actually on the LP, then it would seem probable that something similar is also on any music LP i.e. definite spurious harmonics of the recorded music.

Is there any hard general evidence pointing to either the media or cartridges, or both, as a general aspect of vinyl audio?
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