[rsaavedra]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif However you call it: Vibration reduction is a highly likely scenario (independent of the audible effect it may have)

I disagree, I really don't believe that vibration reduction is highly likely. Precisely because I think most CDs come pretty well made already, well round and concentric.

The company making the device should show (verifiable) numbers indicating what the variance and distribution are about those construction metrics in standard CDs, and how much better the device leaves those metrics in the CD after the treatment. If they haven't done that, (provide evidence instead of simply words,) then they are speculating as wildly as the rainbow foil which respect to what each device does respectively.

Then there is of course the issue of whether whatever changes in those construction metrics they can achieve does really reduce vibration and to what extent, and if it does have any measurable effect on CD playback. But first things first.

 

[JaZZ]

Quote:

Originally Posted by nautikal /img/forum/go_quote.gif Nope. Apparently all you need to sell an eccentric product is speculation, a doctor, and some random numbers.

You forgot audition -- apparently of inferior importance for some people. But indeed I don't need numbers for that.
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[JaZZ]

Quote:

Originally Posted by rsaavedra /img/forum/go_quote.gif I disagree, I really don't believe that vibration reduction is highly likely. Precisely because I think most CDs come pretty well made already, well round and concentric.

I disagree on my part. During ripping with EAC, every CD makes an individual noise, obviously depending on its vibration behavior. Some are really loud.


Quote:

Then there is of course the issue of whether whatever changes in those parameters they can achieve does really reduce vibration....

Reducing mass on the circumference will automatically reduce vibration in any case -- as stated earlier --, that's not hard to imagine.


Quote:

...and does have any measurable effect on CD playback.

That's indeed still open to debate and a case for listening tests -- if possible without any bias. (Edit: I see you wrote «measurable», not «audible»... which is of greater interest for me.)
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[nautikal]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif You forgot audition -- apparently of inferior importance for some people. But indeed I don't need numbers for that. .

You need the placebo effect though.

 

[rsaavedra]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif Reducing mass on the circumference will automatically reduce vibration in any case

Not necessarily. You can reduce mass in the circumference and produce a non concentric CD which has higher vibration than the original, even if with slightly less mass in the border. That's why the numbers matter. Is this device capable of modifying the CD so that it really ends up more concentric and round than the originals, always? Under what tolerance levels does it accuracy fall?

It would be interesting if the device actually checked for the original roundness and concentricity and wobbleness of the CD, and measured how it did and showed those numbers, and in some cases suggested that the trimming wasn't required. Interestingly, this isn't done at all.

Tire alignment in a car starts with first checking whether the alignment is required, isn't it?

 

[nautikal]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif Reducing mass on the circumference will automatically reduce vibration in any case -- as stated earlier --, that's not hard to imagine.

That's not true. By reducing the amount of mass around the circumference, you lower the moment of inertia of the object. Moment of Inertia, I = ΣMR², or the sum of the every point mass times its distance squared from the center of the object. By concentrating the mass more towards the center of the disc, you lower its inertia. This means it takes less force and energy to to cause rotation or wobble. If this is hard to imagine, think about when you hold your arms out when trying to balance. You raise your moment of inertia so a small, unbalanced force is less likely to cause you to fall.

 

[JaZZ]

Quote:

Originally Posted by nautikal /img/forum/go_quote.gif That's not true. By reducing the amount of mass around the circumference, you lower the moment of inertia of the object. Moment of Inertia, I = ΣMR², or the sum of the every point mass times its distance squared from the center of the object. By concentrating the mass more towards the center of the disc, you lower its inertia. This means it takes less force and energy to to cause rotation or wobble. If this is hard to imagine, think about when you hold your arms out when trying to balance. You raise your moment of inertia so a small, unbalanced force is less likely to cause you to fall.

You seem to mix up vibration with wow and flutter. Reducing the mass on the outside border of a CD will most likely reduce its proneness to vibration, though.
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[hempcamp]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif You seem to mix up vibration with wow and flutter. Reducing the mass on the outside border of a CD will most likely reduce its proneness to vibration, though. .

This is a perfect example of bringing turntable terminology into an area where it has no application. Wow/Flutter/Vibration/whatever you want to call it doesn't change the fact that we can test with 100% validity whether or not the finite set of data being read from the CD (and passed to the DAC) is indeed the exact same finite set of data we want read from the CD.

--Chris

 

[JaZZ]

Quote:

Originally Posted by rsaavedra /img/forum/go_quote.gif Not necessarily.

Yes, but there will be very few exceptions, if there are any at all. I'm not interested in debating the need for numbers and the absolute evidence of the pretended vibration reduction. It's just funny how you can equate a logical scenario like this with rainbow foil with no imaginable physical effect.
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[JaZZ]

Quote:

Originally Posted by hempcamp /img/forum/go_quote.gif This is a perfect example of bringing turntable terminology into an area where it has no application.

No, I'm not doing that. You must mix me up with somebody else.

Moreover you forget jitter -- but that wasn't my concern.
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[rsaavedra]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif It's just funny how you can equate a logical scenario like this with rainbow foil with no imaginable physical effect.

There is a difference in how outrageous the claims from each company can be with respect to what their devices can do. Yet, lack of evidence is lack of evidence. They are in the exact same bag as far as that goes.

 

[JaZZ]

Quote:

Originally Posted by rsaavedra /img/forum/go_quote.gif They are in the exact same bag as far as that goes.

That's an extremely subjective and (purposely) biased rating, if you ask me. So why am I not interested in trying Rainbow Foil?
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[rsaavedra]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif That's an extremely subjective and (puposely) biased rating, if you ask me.

Well I didn't ask you

But it isn't biased at all. It's simply that neither one has provided evidence supporting their claims. There is no bias or subjectivity in assessing that.

 

[nautikal]

Quote:

Originally Posted by JaZZ /img/forum/go_quote.gif You seem to mix up vibration with wow and flutter. Reducing the mass on the outside border of a CD will most likely reduce its proneness to vibration, though. .

The vibration is caused by high frequency wobble. Are you going to back up your statement with logic and scientific principles, or are you just going to say the equivalent of "reducing the mass on the outer portion of the disc will reduce vibration because you reduce the mass on the outer portion of the disc?"

 

[monolith]

Quote:

Originally Posted by nautikal /img/forum/go_quote.gif The vibration is caused by high frequency wobble. Are you going to back up your statement with logic and scientific principles, or are you just going to say the equivalent of "reducing the mass on the outer portion of the disc will reduce vibration because you reduce the mass on the outer portion of the disc?"

His point was that you're saying it might cause vibration without saying anything about what that vibration does, if anything. Wow and flutter are real effects in the analogue world. People seem to be demonising CD vibration without actually qualifying whether CD vibration matters at all when it comes to reading accuracy.