Shaving and colouring CDs improves their sound - snake oil?

Retro

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Cutting a 36 degree angle into the edge of a CD with a special gadget* called Audio Desk Systeme (nice bit of French there) and then painting it black improves the sound greatly, allegedly.

You probably have an idea on where I stand on this given that CDs are digital so the data can either be read or not read. However, I'll let you decide for yourself by watching this video by Techmoan where he tests the gadget and does a proper, scientific comparison between treated and untreated discs, clearly showing the difference in audio between them.

After watching this, it'll be time for you to rush out and buy expensive HDMI cables to improve your TV picture...

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*It's no longer made, what a surprise.

 

Arantor

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Haven’t watched yet - am at work - but best guesses:
* polishing the disc to reduce error rate
* darkening the surface to reduce light scatter/diffusion
* sharpening the edge to make it spin in a more balanced way

Reducing the error rate is important - CDs carry more data than you can (normally) hear but if you lose some due to error correction being necessary, that kinda goes out the window. So polishing the disc and giving the laser a better chance of working would help, though so would cleaning the inside of your CD player…

As for buffing the edges or hacking at them with a lathe could in theory improve how nicely it rotates meaning less error correction too, but also less vibration than the DAC and other audio has to process out.
 

Retro

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Oh, you definitely need to watch that video! :)

As for the laser tracking the disc, you'll be surprised what the CD player can handle. I've got a CD single, as in one of those physically smaller CDs, which has got a manufacturing fault on it: the silver layer looks clearly off centre to the naked eye. Yet, it's never once skipped in a CD player and if I put it in a player with a window, then you can see just how fast that silver layer is vibrating.

Gotta admit, I didn't think a player could handle that, but I've not had errors in any I've put it in. Even ripping the track at several times normal speed on the PC didn't produce errors. It's this decoupling of the signal from the physical world that gives digital its power and I love it. Digital technology is one of the best inventions ever.
 

Arantor

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Sure, but the reality is that the CD player is doing error correction on the oversampling that went into the audio in the first place, so it will handle quite a lot.

Just it could well be possible to improve on it without it being snake oil. I have seen such products over the years - CDs are actually older than I am - and certainly there’s been “controlled studies” with blind tests going on to see which measures might be better.
 

Retro

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Just watch the video and then come back to me.
 

Arantor

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Well, placebo effect is a powerful thing, but let's start with my original take before I'd watched the video.

I'd certainly heard the claims before, and I've been around enough that I've also seen the disc polishing and 'disc fixer' stuff over the years, and had some idea of the theory behind the claims.

From a purely technical standpoint, the Red Book standard (the official spec for classical audio CDs, later updated to the Scarlet Book to encompass SACD) talks a lot about its layers of error correction; you have the EFM (eight to fourteen modulation for how it physically gets encoded on the surface platter), and then you have oversampling so that's absolutely a thing, and if you're not running into the oversampling you will get the 'original' rather than a slightly reconstituted version.

So I can buy the theory that if your disc is cleaner, you don't have to listen to the error correction or rely on the oversampling.

And I can buy from a scientific perspective that the light refracts through the clear outer coating and that the black cover would cut that out - again, the physical properties of how Red Book audio defines what a CD 'should do' makes sense to me.

And yes, I can buy the notion that filing the edge off for balance prevents physical vibrations that influence the electronic noise that the DAC is handling down the line.

Now, I will give you that his test was smart enough to eliminate the likes of the DAC from it. What I will also give you is that I think his equipment is superior to what people were using back at the time. This makes a difference.

CD players of the era only really did 1x playback - anything else was a fudge - which means you're getting into reading the data stream at the correct speed and accepting any faults as they are because you have no time to read ahead and buffer. Newer devices had the time and capacity to read ahead and attempt to hit all the data and error correction because you can do it more than once in the time you have, meaning that you have a much better chance of hitting the data as it was originally encoded, and not reliant on synthesising it through the error correction.

Such measures - if they work - would have been for the gear of the time, trying to fix the media to make playback better then. The reason the company no longer sells them is partly because buying CDs is hardly the market it used to be, the mixing/mastering of CDs now makes such error correction utterly unnecessary and by extension such fixes also unnecessary.

I would, by way of other studies, refer you to a review where someone tries to discern discs from the individual measures rather than the holistic view: https://www.enjoythemusic.com/magazine/equipment/0603/audiodesk.htm - this is more contemporary to the device when players were still more susceptible for it.

As to his comments about it applying to DVD that actually does make more sense than it does for CD. DVD data (especially prior to Blu-Ray) was encoded on a disc in a compressed fashion, so any loss will *absolutely* be taken care of by error correction logic because the entire MPEG standard is about reconstituting missing data from inference (and it doesn't use RGB, but starts with luminesence as the primary driver, meaning that more data being able to be saved does mean crisper blacks and lighter lights)

Normally I'd get in with the debunking crowd, but this one is genuinely a little more complicated than 'the data's digital, pfft' because there's a mass of electronics that operates very much in the analogue that sits next to it.

I should add, I have some not-so-fond memories of trying different techniques to rescue damaged CDs from back in the day that people thought were weird but have practical science attached to them. At one point I had a kit with several different kinds of brush, a couple of different buffing pads and a small tube of supermarket own brand toothpaste as a mixer. Rescued a number of mates' scratched CDs with that little kit - but of course I haven't needed it in years.

And as for gold plated HDMI, yeah, no thanks. The data comes out of one end already digital, goes in the other already digital, the gold plating, it does nothing!
 

Retro

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Right, I'm gonna have to put a spoiler here for those who haven't watched the video and I'm not using spoiler tags for something like this.

Well, for all that, the proof was in the eating: Techmoan created a difference file in Audacity between an original disc and a treated disc: zero output. That means that the data was the same and therefore the treatment did nothing for the sound. This is hard evidence that cannot be argued against. A slam-dunk win.

While drive electronics, mechanisms and lasers are expected to improve over the years, they would improve overall reliability and slickness of operation, not sound quality. A better DAC, analog-side filters etc on the other hand, would.

All that stuff in those so-called "reviews" about better bass, improved soundstage etc were lies, flat out lies as anyone who isn't conned by such claims knows. They were probably paid to say it, or otherwise very deluded, with a heavy dose of confirmation bias. In the analog domain it could have been a different story.

The fact is, that if the error correction can fully deal with the error(s), then the recovered signal is the same as that with no errors to begin with. That's the power of digital processing right there, decoupling the signal from the ravages of the real world. If it doesn't work, ie overloaded with too many errors, it will normally result in momentary pops that you can hear. There's a slight fudge that the error correction on CDs can do if it's borderline, to interpolate the signal to hopefully avoid a pop, but that's it. The Techmoan result clearly shows that this wasn't needed, or a difference would have been seen. Note that with data CDs, ie discs formatted for data, this interpolation function is missing as it still amounts to corrupted data. The spiral is also divided into defined sectors, rather than continues stream of data, as 100% recovery of data is so much more critical than with audio.

Now, having said all that, I remember my CD burning days of the early 2000s using the high end Plextor DVD burners. They had software that plotted a graph of read errors right across the disc, with better discs giving lower errors and hence longer term reliabilty, especially in the face of light physical damage like scratches. Weirdly, the error rate sometimes went down with higher write speeds, but that's another story and I don't know why that was.

Now, it would be interesting to measure the raw error rates from those two discs on a Plextor drive and see if it's any better after treatment, ie measure the same disc before and after treatment. I'll hazard that the result would either show no difference, or perhaps slightly worse. Unfortunately, there's no way to test this now.

Bottom line is that I would never chop up my CDs as it's simply damaging them for no good reason. This is a snake oil product that should never be used. Perhaps kept in a museum as an example of such things used to con people.

btw that article you linked to debunks itself with the following line near the start:

After all, I had already found that just about anything you did to a CD was likely to make it sound better -- cleaner/polishers, rubber bands (or green marker) on the edges, demagnetizing gadgets, anti-static liquid -- you get the picture.

Oh, really? I can read the rest out of interest, but on seeing this, it's not surprising that he'd allegedly find a difference in audio quality where there is none. Don't be fooled.
 

Arantor

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The fact is, that if the error correction can fully deal with the error(s), then the recovered signal is the same as that with no errors to begin with. That's the power of digital processing right there, decoupling the signal from the ravages of the real world.
You seem to have missed the point I was making.

If you can *fully* deal with the errors, you get perfect reproduction, because it's digital data.

But for *discs of the era* played in *drives of the era*, fully dealing with the errors wasn't necessarily as possible as it is now because 20 years on has improved some things and some fixing of the signal could indeed happen by way of using the error correction. Accounting for the fact that you're handling 44100 x 2 samples per second means that you can actually interpolate quite a bit before you lose the signal entirely (which is what a skip is, where the disc is too degraded for even the error correction to fix it)

It's actually surprising how poor the drives of the era could be. I had a DVD drive made in 2000 that couldn't actually read DVDs properly. It could read them - eventually - but never fast enough to play the video back fast enough once it went past 57 minutes (and into the second layer of data)

I should also add that my CD player definitely had issues with discs that weren't balanced properly, there'd be a buzzing noise that absolutely wasn't there when the disc was played in other drives and there was nothing 'wrong' with the disc because I could rip the data and verify the content.

But again, I'm not being fooled. I'm merely aware that some of the claims may have been possible on the hardware of the time and that there are some bases for that which make sense. But 20 years have happened since and things change.
 

Retro

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Sure, the drives have improved a fair bit since then, as I said myself, but again, interpolated audio wouldn't last more than a second or so at the very most. It's not like there's gonna be a noticeable drop in sound quality because of it.

Clearly your DVD and CD drives were faulty, or had a design fault, no matter when they were made. Most sold worked ok.

Also, this CD Mutilator(tm) came out in 2003, by which time CD & DVD technology was quite mature and hence would work better than those early devices anyway, further debunking its claims.

It remains that this product is snake oil, but which you seem to be giving some sort of legitimacy too.
 

live627

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I have an unrelated anecdote about CDs: When I was 14 or so, I had some game on a CD going in a CD drive... at 56x. 56x! NI guess the disk was damaged because it ABSOLUTELY SHATTERED! In a panic, I cut the power and removed the drive (I knew how to work on computers, so changing out a disc drive was easy peasy). Further examination yielded broken pieces. Shaking it confirmed that there were indeed broken plastic fragments inside. The metal housing was undamaged and kept the plastic shrapnel enclosed. I extracted two or three chunks before throwing it away.

Needless to say, I'm terrified of them if they advertise speeds greater than 48x.
 

Retro

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Oh yeah, 56x drives were withdrawn because of this problem, so you're quite rightly scared of them. CDs were never designed to withstand such g-forces. It's quite possible for the shards to punch through front of the drive and seriously injure anyone near it, too.

Was your drive trashed by the exploding CD?

Later drives were limited to 48x to alleviate this problem. It would be interesting to see how fast drives could get if this hadn't been a problem. The processing speed of the electronics and reaction time of the servo must be phenomenal to track and read a disc at these speeds, even 48-56x. Quite the engineering feat. Shame they're pretty much obsolete now.
 
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