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Strange Oscillation

Alright, I need to get to the bottom this. On a couple of CD's at certain passages, the music goes into an oscillation and won't quit until the volume is reduced or the disc stopped entirely. My playback source is an Ayre C-5xeMP, Plinius Tautoro pre and Plinius SA-103 amp. Interestingly this only happens on a few CD's and usually when there is a sustained chord such as from a keyboard note that is held or a sustained vocal. Two examples are Pink Floyd, Dark Side of the Moon, track one about mid point with the EMI Japan release CDP746001 Z. I also have the MFSL issue and it plays with no problem. Another example is Patricia Barber, Cafe Blue standard redbook release during a sustained high pitch vocal note and only at high volume. So what causes this to occur? It is obviously related to the CD itself since DSOTM MFSL issue plays just fine. Can anyone enlighten me?
128x128falconquest
falconquest's avatar
falconquest OP
1,108 posts
 
oleschool,
I assume you mean from a vibration standpoint. The Ayre sits on a solid maple shelf almost 2" thick and from there is perched upon vibrapods. I really don't  think vibration is the cause but at this point can't rule anything out. What's interesting is that it happens only on certain CD's.
kijanki's avatar
kijanki
4,432 posts
 
I have Cafe Blue, standard CD and cannot hear any high pitch vocal.  In fact, it is the one of the best recorded CDs used for demo in many stores. Can you point to particular song, minutes, seconds?

Vibrapods might protect CDP from vibrating shelve, but will do the opposite when CDP body vibrates.  Did you try to remove them?

Perhaps laser is weak (dirty).  Try to clean it.
falconquest's avatar
falconquest OP
1,108 posts
 
kihanki,
No high pitched vocal? I am referring to the track "Too Rich for my Blood" (one of my favorites) at about 5:19 when Patricia hits that high note. So how does one go about cleaning the laser? I'm certainly open to trying that.
oleschool's avatar
oleschool
722 posts
 
My only reason for saying iso was just a "try it thing" I have a cple cds when I am getting down I get nervous at certain points because they have let loose a serious ocilation in the left driver at dam near the exact time ( not clipping my amp not even close).I always figured i was pushing it too hard and overdriving the driver .But it again happens in a cple select cds .You seem to have iso I still would pull the maple and iso and try it if its not hard.I doubt thats it ,it’s probly in the cd.Do you have another setup or another freind to try it on? Not mine lol ... good luck

kijanki's avatar
kijanki
4,432 posts
 
Falconquest, I just checked - it is clean. I used high volume on headphones and speakers.  There is a lot of sibilants, more vivid with headphones, but still clean.  5:19 high voice note is very clean.  You could clean laser with laser cleaning CD.  I was suspecting time jitter of digital signal, that converts to noise, but it would shows in unpleasant sibilants first.  I suspect, that you have some system or room resonance at this frequency.  Try to eliminate things.  Is it tweeter?  Is it in both channels?  Can you borrow another CDP or rip it and play it from computer or the phone?  Better yet, can you take this CD to a friend?  
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