Any suggestions for repairing a scratched music CD?

[Frank]

Toothpaste is good. I used to use it to buff up a plastic watch crystal. I would avoid solvents as polycarbonate is soluble in many.

[FromTheRafters]

I worked on/with Sansui's PCX-1 and PCX-11 which both used that method. It was probably Sony technology anyway. A lot of brands had competitor's technology inside anyway. What it says on the outside was often not what it said in the inside.

I saw some of those, but never had to work on or with them.

Yes. THD (Total Harmonic Distortion) ratings of .008% or whatever when most people couldn't even detect 10% clipping.

I had a quick look, and might go back for a read when I feel the need to be punished.

[Bud Frede]

They're helical-scan drives similar to Beta or VHS, but much smaller. The tape is 4mm.

I saw businesses using them for data backups, and finding out that the tape they made a year ago can't be read in the drive now since it's worn and the alignment has changed.

There are also larger versions using 8mm tape. I think there are a couple formats for data and at least one for video. They're a bit more reliable than DAT, but not nearly as good as drives that use linear tape (not helical-scan). Come to think of it, I think these were used for audio as well. I can visualize one of those all-in-one recording consoles with a tape drive built in and it was 8mm.

There's a lot of that. Pick something to optimize and then show everyone how your product is 10 times better than everyone else's as measured by this one metric. Then hope that nobody notices that the overall performance isn't that great. :-)

Some people almost make a fetish out of "high end audio." There are people who buy very expensive fractional-watt tube amps that use directly-heated triodes and are single-ended, not push-pull. Then they get some boutique cone speaker, often with a whizzer cone, and proclaim that it sounds better than anything more modern.

These are also the people who won't listen to anything but LPs and then only ones where the whole recording process was analog too.

I met a couple of guys with systems like these locally. They were telling me how wonderful their systems sound. In both cases they had them in the basement, with cinder-block walls and concrete floor.

One guy was into weird cables and he had them all suspended from the ceiling via strings from tacks in the joists of the floor above. It looked like something you'd attach over a baby's crib and set to spinning. He also had AC power cords that were as thick as fire hoses. He had replaced all the fuses in his equipment with solid copper rods because he thought the fuses were too "restrictive."

Next he told me that his $10K turntable had stopped working, so we would have to listen to CDs instead. Then we found that his very expensive CD player only liked a few of his CDs. He kept trying to load them and it kept spitting them out. Once he did get one to load, it skipped several times and then settled down.

He didn't have much room in his basement, so you had to sit very close to the speakers. Needless to say, it sounded terrible and I had to keep from laughing at him.

There's some lunatic in the UK, Peter Belt, that sells the same kinds of products. He recommended that you use a sharpie to write "OK" on all of your CDs to make them sound better.

[FromTheRafters]

I know, the company I worked for had us QC them, but I never had to repair one or align one. Helical scanning mechanisms can be very 'picky' as to alignment.

You can use the desired tape and align them to that, but if you use an official alignment tape you may even make matters worse. I imagine it can be even worse with the smaller size of the DAT mechanisms.

[...]

No mattresses, molded foam, and egg cartons glued to the walls - amateurs. :)

Ha ha ha, that's a new one on me.

Audio diplomacy. I had friends with 'boom boxes' turned way up, Exclaiming how great it sounds, and I just couldn't listen to them. Diplomacy only goes just so far.