How Can a CD be Selectively Attenuative?

I apologize if the subject line for this topic isn’t very clear. I am personally annoyed by subject lines like, “What does this mean!?!?” which gives you no clue as to what the question is. However, the question I am posing simply can’t be crammed into a few characters. So please forgive me.

Okay, here’s the beef. When I was in London, England, I bought a CD entitled “The Nice”, which is basically the digital version of one of my favourite vinyl disks (which is entitled “Azrael Revisited”.)

Anyway, when I popped the CD into my portable player, I was disgusted that my favourite tune (“Azrael Revisited”) sounded just awful. The vocals were almost inaudible. Indeed, it sounded like I was merely hearing bleed-over from an adjacent microphone in the recording studio. At that point, I concluded that somebody had really messed up the remix. (I have similar complaints about the drums in the song “One More Red Nightmare”, by King Crimson, on the CD version of their “Red” album, but that’s another matter.)

However, when I tried the Azrael CD on another CD player, the vocals came through just fine. I sat back, delighted, and enjoyed the wonderful music from the group that predated and prefigured Emerson, Lake and Palmer.

So here’s my question: if CD music is just digital data, how could there be a loss of the vocal information, when my “Azrael” CD is played on a particular CD player? Doesn’t a CD just deliver an essentially linear stream of bits?

In case I haven’t stated my point strongly enough, let me emphasize it: the CD “loses” the vocals when played on my portable CD player, but it works fine on my desk model.

What gives?

Either speakers or disc player itself must suck. Check other recordings on both systems and you will be able to answer that possibility…

Yer pal,

Sounds like you got a compressed CD. Old CD players don’t play compressed CD’s as well as regular CD’s. The newer CD players have no problems with them.

How old are both CD players?


I’m not sure. I got acceptable performance from the 24x CD-ROM player on my computer (which is manufactured by Creative Systems). The portable CD player which gave me the original headache is a Panasonic SL-SW405 model. It’s not ancient; it has about ten seconds of anti-skip memory.

I “get” that some machines will handle compression worse than others, but this still doesn’t explain why, on the CD I mentioned, it’s only the vocals that seem to be affected. I will admit, however, that perhaps this is an example of selective attention. That is to say, maybe other aspects of the recording are compromised, but I only noticed the vocal part.

Nonetheless, I’d be interested to hear if anybody else has experienced this problem and knows what causes it.

Errr… You’re sure you’re not simply losing one of the two stereo channels?

John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams

I have found on some CDs I play on my portable CD player will sound awful if I play it with my anit-skip on. They sound beautiful if the anti-skip is off. And this is just on certain CDs. Go figure.

Kennedy’s right on this one. I had the same problem with a Beatle’s CD where I would get only half the lyrics on “When I’m Sixty-Four”, IIRC.

John W. Kennedy: I think I would have noticed if one of the stereo channels was out on my portable CD player. After all, I listen to it with headphones! In any case, the problem only afflicted that one CD; all the others sounded fine to me.

CD players decode the digital data, then run the analog output through a series of high and low cutoff filters to get rid of artifacts. Perhaps the filters in your portable CD player aren’t very good? Maybe there’s actually an electronics failure.