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Re: [AV Media Matters] Polishing of CDs
Dear Mr Gibson
ggib> Dear Mr. Iraci:
ggib> Thank you for your very valuable information.
ggib> It is very unfortunate that the manufacturers of the products you
ggib> tested have not provided us with such information.
I think I, sort-of, touched on this in my other posts on this subject.
The cost of such test equipment is not exactly pocket money level. To
keep the selling price of the equipment down to a reasonable level,
the manufacturer is reluctant to spend a lot of money on test
equipment - particularly where a decent pair of ears is available (at
least where Audio discs are concerned).
In the final evaluation, the end-user has only one concern - does it
work? Telling him the BLER is higher is of no interest to him
You have to also understand that there is an utterly incredible lack
of understanding about CD's in general, at the public level. I spend
half of every day in *educating* the public about the way these things
are manufactured and therefore why it is possible to repair them.
If I had a dollar for every time I have been asked 'Won't it rub the
songs off?', I could have retired on the money :-). Of course, the
alternative question is 'Can you do that to my LP's and get the
scratches off?' Against that sort of background, you want the
equipment manufacturers to start publishing BLER figures - I think
I'm not saying that the figures given by Mr Irachi are incorrect, but
I have to say that one line in his post gave me cause to suspect the
way that were arrived at, to wit;
ggib> Polishing the disc for several hours with the highest grit paper
ggib> could not remove all of the scratches.
Now, (almost certainly) unlike anyone else in this group, I actually
*own* a Fix-A-Disc repair machine. As a consequence, I have fixed
more discs than Mr Irachi has had hot dinners, so I think I could
fairly claim to have some little more practical experience in its use
If one of these machines was set up to grind a disc for 'several
hours' - there would be no disc left!!! Which leads me to suspect the
grinding pressure was incorrectly set or the grinding paper was
totally worn out, before embarking on this marathon.
Also, I would say it is not possible for the machine operator to
achieve consistently good results without some lengthy practice. Like
most things mechanical, there is a 'knack' to using it, which can only
really be acquired through experience. How much 'practice' with this
machine was there, before these results were attained?
ggib> Therefore, from this small study it is evident that polishing
ggib> appears to be hit or miss.
I'm rather disappointed that a professional should publicly damn
something on the basis of what he admits is a 'small study'. This is
not the sort of thing which I expect to find here.
ggib>This was especially evident in the unscratched CD-R that was
ggib>through the process (as a control).
The disc may have been used as a 'control' but what about the other
elements - the operator's training/experience, the state of the
grinding papers, the state of the pads, the rate of water flow, etc.,
Frankly - this strikes me as sloppy science and I think it unfair to
pronounce on any process on the basis of such minimal evidence.
I don't want to bang on too much about this equipment - after all I do
import it to Spain and I obviously have a vested interest (although
anything I say here is not going to affect the pesetas in *my* pocket)
- and I don't want to sound like an advertisement.
But the important point is - if a 12 cm optical disc doesn't work and
we can repair it so that it does work, then we have happy clients.
Our recovery rate is around the 85-95% level. It may not be the best
system for optical disc repair - but it's the only one we have at this
Audio Restoration and CD Repair