'Shaving Compact Discs to Improve the Sound?!' - What Did Techmoan Get Right and Wrong?

I critique Techmoan's video "Shaving Compact Discs to Improve the Sound?!" and explain what he got right and wrong. I also go into more detail about the error correction methods used in CDs, and how that relates to the CD "shaver" he evaluated, and the conclusions he reached.

[sharktooh]

The CDs output is perfectly identical. CDs were used for data storage too and if you burn 2 CDs with data files, the output files are BIT IDENTICAL.

[vwestlife]

I'm all for Fair Use, but this is pushing the limits. You could have critiqued Mat's video without replaying the entire thing.

[Coneman]

A CD made perfectly symmetrical to the centre hole reduces vibrations. I think this is the main mechanism of how it can help the sound.

[EVmike]

Reed Solomon does have limits, but that's why the process is run twice.

Wiki says it thusly: The CD system employs two concatenated Reed–Solomon codes...

[Fotosaurus]

I bought a CD off eBay and it would not play on my portable cd player. I put new batteries in, still nothing. I opened the cover and spun the cd around. I could hear a slight rumble. I took it out and examined it. It appeared to have an edge all the way around that stuck out. The edge was not flat. So I took a razor knife and trimmed about a third of a millimeter all around the edge. It plays now. Weird.

[facilegoose]

If there are measurable differences (or improvements), I'd suspect the geometry of the laser refraction in an out-of-spec CD to crop up in a particular pattern throughout unique to that disc., caused by the point-source losing coherence in those spots. We'd need all the tracks, correction free takes (if possible), and takes from scuffed discs to be thorough. More interested if there's negligible non-zero effect one way or the other.

[jaysonl]

There's only one way I can think of this stupid disc "tuner" could actually help. I remember having an audio CD (I think it was a No Doubt album) that was so badly out of balance that the act of spinning it up caused a lot of vibration noise from the drive itself. I betcha this thing could have fixed that.

[Coneman]

How can you measure the errors in something by using the same device that has the same errors?!

[Coneman]

A digital wave is an analog wave with digital encoding. That encoding and decoding can cause errors. It’s not perfect.

[Coneman]

Assumptions in this video which are wrong.

[Coneman]

Yet CD transports can sound different. You can’t explain that.