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Audio CD high frequency artifacts, is it some kind of signature
2E7AH
post Jun 3 2010, 16:12
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I think that something like this was brought to this forum, but I just can't find the thread.





In case I'm wrong I wanted to ask what's the purpose of such artefacts: one disc is PIAS release and the other is Centerpointe for example, thou there are many others, and I guess I lack some general knowledge about it, but curious to ask smile.gif



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saratoga
post Jun 3 2010, 16:31
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CRT noise maybe?
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2E7AH
post Jun 3 2010, 16:39
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they are on different range, so I guess it's hard-coded on CD itself
+ I have other similar examples CDs, all on different spectrum ranges
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saratoga
post Jun 3 2010, 16:45
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QUOTE (2E7AH @ Jun 3 2010, 11:39) *
they are on different range, so I guess it's hard-coded on CD itself
+ I have other similar examples CDs, all on different spectrum ranges


Sorry, I meant CRT noise in the recording studio. They may have used CRTs while recording, and the mic picked up some of the hum. Just a guess though.
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2E7AH
post Jun 3 2010, 16:49
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that would be strange, as I have also other examples as I wrote, so I guess also other users have similar experiences with their Audio CDs
these are of course legally bought and well paid CDs, the artifact is inaudible but present is spectra as some kind of signature on first thought
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lvqcl
post Jun 3 2010, 17:02
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About 15625/15734/15750 Hz:

http://www.hydrogenaudio.org/forums/index....showtopic=17212
http://www.hydrogenaudio.org/forums/index....showtopic=28244
http://www.hydrogenaudio.org/forums/index....showtopic=49652
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2E7AH
post Jun 3 2010, 17:17
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thanks lvgcl smile.gif I know that there were some similar threads, and thou I said it's inaudible, that's maybe the case for 20KHz artifact on my ears but not the 16KHz
So I guess that's some interference with studio equipment, but that should be really lame for such studios
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Arnold B. Kruege...
post Jun 3 2010, 18:48
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QUOTE (2E7AH @ Jun 3 2010, 12:17) *
thanks lvgcl smile.gif I know that there were some similar threads, and thou I said it's inaudible, that's maybe the case for 20KHz artifact on my ears but not the 16KHz
So I guess that's some interference with studio equipment, but that should be really lame for such studios


In the late 1970s and early 1980s, some high end recording consoles were automated using minicomputers that included old-fashioned displays that were basically TV monitors. It was not uncommon for recordings made with them to have 15,750 +/- KHz tones on them. These days it is not unusual to find so-called "Hi Rez" recordings with tones in the 30 KHz rnage, related to monitors and switchmode power supplies. Another source of high frequency tones is the bias used in magnetic tape recording, although they were usually above 50 KHz.
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2E7AH
post Jun 3 2010, 19:05
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checking now on other CDs it seems that they are PIAS re-releases from late 80s albums, OTOH Centerpointe's 20KHz artifact could be just as deliberate signature knowing what that studio produces, but just look at similar product which I won't advertise (and this product was alive in late 70s or early 80s, I'm not sure, as tape until now when it's available on CD and have both ~16KHz and 20KHz artifacts):


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dhromed
post Jun 3 2010, 22:37
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lvqcl's first link mentions an 18KHz+ tone. I guess I now have the probable inspiration for Autechre's 18.2 KHz easter egg [png, 220K] in Second Bad Vilbel. The music's loudness masks the fade-ins and -outs completely, and I can't hear* the actual 18KHz tone anyway, but when I opened the spectrograph I said to myself: What the F is that?!


*) That, or the sum of my equipment doesn't reproduce anything above ~17.2KHz. I'm not sure how to rule it out. The cutoff is relatively sudden, when tested with foobar's tone generator, but I don't know what that points to, if anything.
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