[sonitus mirus]

Even with CD-4, the useful audio frequencies don't appear to be much over 15kHz from the samples I could find online.  The CD seems to be technically superior in creating signals at the highest audible frequency range.  
 
An old Popular Science article, just for fun:
 
https://books.google.com/books?id=9OEDAAAAMBAJ&pg=PA67&lpg=PA67&dq=cd-4+carrier+signal&source=bl&ots=n2fHOiZK3Y&sig=bdpJP9rAGCGiz1H-9NGVHT5dIx4&hl=en&sa=X&ved=0CCsQ6AEwA2oVChMIm9n189bHyAIVQh4eCh1JZAsv#v=onepage&q=cd-4%20carrier%20signal&f=false
 
The frequency response deviations do resemble a roller coaster tack with the carrier frequency measurements.

 

[jcx]

the 2 extra audio channels are evidence of the Quadraphonic CD-4 system collecting the 40 kHz modulated carrier with enough S/N to process those ultrasonic frequencies to give the 2 extra channels
 
CD-4 Quadraphonic audio channels are band limited - but that's due to the encoding/decoding choices
 
 
the raw signal from the cartridge has to extended response to beyond 40 kHz

 

[cjl]

  Even with CD-4, the useful audio frequencies don't appear to be much over 15kHz from the samples I could find online.  The CD seems to be technically superior in creating signals at the highest audible frequency range.  
 
An old Popular Science article, just for fun:
 
https://books.google.com/books?id=9OEDAAAAMBAJ&pg=PA67&lpg=PA67&dq=cd-4+carrier+signal&source=bl&ots=n2fHOiZK3Y&sig=bdpJP9rAGCGiz1H-9NGVHT5dIx4&hl=en&sa=X&ved=0CCsQ6AEwA2oVChMIm9n189bHyAIVQh4eCh1JZAsv#v=onepage&q=cd-4%20carrier%20signal&f=false
 
The frequency response deviations do resemble a roller coaster tack with the carrier frequency measurements.

In order to provide 4 channels at all, the cartridge must track up to 40+kHz. That doesn't mean the audio itself extends that high (nor does the fact that my car radio picks up frequencies around 100MHz mean that it plays back frequencies that high), but it does mean the record can record and reproduce that kind of frequency.

 

[sonitus mirus]

 
In order to provide 4 channels at all, the cartridge must track up to 40+kHz. That doesn't mean the audio itself extends that high (nor does the fact that my car radio picks up frequencies around 100MHz mean that it plays back frequencies that high), but it does mean the record can record and reproduce that kind of frequency.

Is the FM carrier signal recorded or generated?  Are any recorded frequencies coming from the instruments being captured at high enough decibels to be present above any unwanted noise?  
 
Edit: recorded frequencies at or above 16kHz

 

[cjl]

  Is the FM carrier signal recorded or generated?  Are any recorded frequencies coming from the instruments being captured at high enough decibels to be present above any unwanted noise?  
 
Edit: recorded frequencies at or above 16kHz

The FM carrier signal is generated by the radio station, which must be able to produce signals in the range of 100MHz or the radio wouldn't work. Similarly, the vinyl must be able to contain and reproduce signals in the 30-40kHz range for CD-4 to work. As for the recorded frequencies, it really doesn't matter. Because of the way CD-4 works, no, there are not signals at 30+kHz from the instruments themselves. However, it demonstrates that vinyl can hold and reproduce such frequencies. You could (in theory) use a similar setup but directly play back the 30kHz frequencies rather than demodulating them to generate the quadraphonic sound.
 
 
Note: I am NOT arguing that frequencies over 20kHz are common or important in music. I am not claiming that they make ANY audible difference AT ALL. I am merely stating (with evidence) that LPs are technically capable of frequency extension well beyond that of a CD, even though it makes no difference to the audio quality of the music itself.

 

[sonitus mirus]

 
The FM carrier signal is generated by the radio station, which must be able to produce signals in the range of 100MHz or the radio wouldn't work. Similarly, the vinyl must be able to contain and reproduce signals in the 30-40kHz range for CD-4 to work. As for the recorded frequencies, it really doesn't matter. Because of the way CD-4 works, no, there are not signals at 30+kHz from the instruments themselves. However, it demonstrates that vinyl can hold and reproduce such frequencies. You could (in theory) use a similar setup but directly play back the 30kHz frequencies rather than demodulating them to generate the quadraphonic sound.
 
 
Note: I am NOT arguing that frequencies over 20kHz are common or important in music. I am not claiming that they make ANY audible difference AT ALL. I am merely stating (with evidence) that LPs are technically capable of frequency extension well beyond that of a CD, even though it makes no difference to the audio quality of the music itself.

 
I was talking about the CD-4 carrier signal which uses FM-PM-SSBFM (frequency modulation-phase modulation-single sideband frequency modulation) technique.  
 
The suggestion is that any sounds above 20kHz on vinyl, and probably even much lower, are nothing more than unwanted noise or some signal not related to the recorded sounds in any way.  What little useful or musical information is hopelessly masked for any creature capable of hearing frequencies that high.  Vinyl can produce ultrasounds, but they are not reproducing sounds picked up from a microphone.  I'm sure there are exceptions, but this is generally what I have found in the little research I spent on the matter.
 
So, yes, an LP can produce frequencies much higher than a CD.  It seems more like a problem, though, to me.

 

[cjl]

  Vinyl can produce ultrasounds, but they are not reproducing sounds picked up from a microphone.  I'm sure there are exceptions, but this is generally what I have found in the little research I spent on the matter.  
So, yes, an LP can produce frequencies much higher than a CD.  It seems more like a problem, though, to me.

This is a statement that I fully agree with. Vinyl as a media looked at in isolation is capable of frequency response beyond CD, but generally any ultrasonic content found on a given record will not be actual musical content, and it generally will either not affect or hinder the reproduction.