CD Transport Rumble

Off balance CD. I've had it happen when someone attached a stick-on label to a CD. At high RPM's, the CD will vibrate. I've also seen a damaged hole in the CD cause the drive clamping mechanism to lock at an odd angle, also causing vibration. If it's only one CD, try to make a copy of the CD. If there is something wrong with the CD, the copy should play normally.

I've seen a few CDs where the center hole wasn't "to spec". It was either slightly undersize, or had bits of plastic "burr" on the edges of the hole. As a result it would not drop down on the drive spindle properly, and the CD would sit at a bit of a slant and would wobble when spinning.

Going around the inside of the center hole with a small piece of fine-grit sandpaper, to break off any burrs from the molding/stamping process, and then cleaning the CD carefully to remove any sanding dust and grit (rinse under running water) has usually worked out. In cases where it doesn't, I'd "rip" the CD and burn an exact copy, store the original and use the copy as a play disc.

I had a CD player that started to do something like this. Passages with only high notes came through well, passages with low notes just dissolved into something that could be called a rumble. It was odd, the beginning of the CD played perfectly, at the end the audio was totally inaudible. It was not a time thing, you could skip to the end of the CD and it would immediately be bad, skip to the beginning and it was fine.

After some poking I discovered the (brush) motor was shot, there were spots where the motor would not start.

I just replaced the whole player, it was quite old. But, it was a very interesting defect that I still don't understand. CDs start at the middle and spin fast, then slow down as they work out toward the edge. Motor speed seemed to have something to do with the problem.

Jon

And, reading the thread again, maybe the OP was talking about audible noise from the transport, not noise in the audio output, which was what I was thinking at first.

Jon

I had a cheap CD player (boombox) that only played the first 3 or 4 songs on any CD. It was not worth sticking money or time into it. I put it in the barn for a barn radio (the radio worked fine). And bought another CD player.

I think the OP was talking about the CD itself making noise, not the sound from the speakers. He said it's classical music. If it was rock music, he probably would not even hear that noise. But I do wonder if the center hole is not exactly centered. I'm sure that could happen....

Hello, and thanks to all who responded. I took a closer look at that problem CD and indeed the center hole is off center. Not much but ostensibly enough to elicit the observed effect in the CD player. Sincerely,

Higher speeds are less affected by motor dead spots, at low speed it would see much more rotational speed variation.

NT

It was odd, the beginning

Yup. I knew what an interpolation sounded like on that player, a little chirp when a block of data would not error-correct. This was different, but maybe the player's chip set had some different method of covering up buffer errors that tried to fake the data. And, I could easily see at the lower speed that it could get lots of buffering errors if the speed was unstable.

Jon

Yep, I had that feeling..... The result of mass production....

Make a copy of it, and play the copy from now on. I'd copy at the slowest possible speed because of that "wobble".