So how come that when I add an isolation pad to my CD player (and amp) the music sounds significantly better then?

To be honest, absolutely no idea - but there is no mechanical decoupling provided by an isolation pad to the laser platform whatsoever. Isolation pads are used for turntables or speakers, since they have mechano-acoutic componentry. The CD player does not have any.

Even were a laser head susceptible to harmonic vibration (and they are not, even the cheap ones, as they are *carefully* designed to stop this), this would only affect the laser's ability to track (side to side) and focus (up and down). Both of these effects are corrected in CD players, so even under the worst mechanical conditions, the error rate reading symbols does not go up very much. Don't forget, you are not using a mechanical interface reading "individual data bits" (record player, although this is a pretty bad analogy), you are using light to read "lumps of data" (CD player).

It is easy to glue a broken pot back together from the pieces since you have indications of the form of the object before it was broken, just by observation. If, however, the pot was smashed and then ground to dust, it would be impossible to reconstruct it accurately since there is less indication of the original form (the "grain" of the pieces is far smaller).

So even if your player was vibrating at the resonant frequency of one vital component of the laser focus unit (they are designed so that each subsystem vibrates at a different frequency that doesn't overlap with another component's resonant frequency), then only one aspect of it's performance (say, it's ability to focus) is affected. Immediately, dynamic compensation to correct it comes into play to try and bring down the change in error rates that are detected. Even if this doesn't work, there's still error correction of the damaged symbols going on ("reconstructing the pot"). Even if this correction doesn't work, there's still interpolation going on to "guess" what the music should have been doing. If all that goes wrong, then the player (usually) just mutes the output for a split second.

So as you can see, it's actually pretty damn hard to get a mechanical effect on the playback of the CD player, short of giving it a really good thump and putting the laser playback head off track for longer than about 220ms, or well beyond the designed mechanical operational range of one axis of the head.

For you to say that an isolation pad has improved the quality of playback, I would be inclined to say that in installing the pad, you have rectified a mechanical or electrical problem elsewhere in the interconnection of your system's units. I would also be be personally inclined not to trust the guy who sold you the pad specifically for this purpose (especially at 70 quid) since it is utterly unsuited for what he purports. Stick it under your Linn Sonndek, your vinyl will sound much better (mind you, if it's a Sonndek, it probably won't need it ). Having read your post again, it looks as if you have bought a complete system with new components. Are you sure the change in sound quality is not simply due to the fact you now have (overall) a much better system than your original?

From my own experience, the greatest influences on playback errors of a CD are in the mastering and stamping process of the factory producing the disks in bulk. I worked on a disk QA system in the 80's that measured the error rate and distribution (see this post) which allowed them to work out the rate of stamper wear. As the stampers are used, they are "plucked" and "stuffed" by the disk material they are stamping. They get clogged up or loose definition, and have to be cleaned. After a while, they wear out and are replaced. "Worn Out" means that the stamper is creating more than a certain rate and density of critical errors on playback of the disks they create. The most critical problems relate to tracking (side to side movement to follow the tracks). As long as the laser stays on track then focus errors caused by a dirty disk or disk warps (or whatever) are easier to deal with, 'cos you are still getting data. If you completely loose tracking, then you loose your data source and kablooey, it's the end of the game (click)



One of the few remaining Mk1 owners... #00015