Re: [microsound] CD vs CDR, again

[the.ca4.organisation <jl@xxxxxxx>]

All this may seem like techie stuff but in my opinion there are two=20
things that really causes audible problems when reproducing more=20
complex music via a digital system. I.e. audible problems that I think=20=

hurts the music. One is jitter and the other one is truncation (the=20
latter is caused by large commecial compromises in algorithms due to=20
the limited processing power available in low-end digital equipment=20
like a PC or a Mac).

The audible effects of jitter can be described as a clogging up of the=20=

audio signal, it becomes more difficult to hear the different layers=20
and nuances of music. There is currently no market pressure to reduce=20
it as the typical commercial pop-production will sound acceptable and=20
it doesnt affect copies of software/data (it is a timing problem that =20=

give the D/A headache).

To reduce jitter with a CDR you could record at 1x or 2x speed. But=20
this is almost impossible today as both recorders and discs are=20
manufactured for hi-speed burning. And low-speed would (to put it=20
simply) over-burn such discs.  Jitter can also be corrected on the=20
player end but it requires an expensive circuit that introduce a small=20=

amount of distortion (its a sample-rate-converter with a very stable=20
clock) or you can copy it to a media that introduces less jitter on=20
playback. I use a jitter-correcting D/A and I very much prefer the=20
correction switched on but in the marketplace distortion is an=20
important number and even slightly higher figures would hurt sales. All=20=

CD-players contain some kind of jitter-reducing circuit in the form of=20=

a PLL.

The other thing you can do to reduce jitter is better manufaturing=20
tolerances (mechanical). A better balanced disc will introduce less=20
jitter in the player and sound better. There are small "cd-grinders"=20
available which you can use to balance a disc better (even after=20
recording, even as a buyer/listener) but they are more expensive than=20
burners etc.

In my opinion it should be possible to make a CDR better a pressed CD=20
with some care, feeding and know-how. The important thing is to=20
remember why you do this (the music) and not go overboard optimising on=20=

one single parameter.

s=F6ndagen den 8 december 2002 kl 05.02 skrev Michael Theodore:

> Hello,
> Having now read more about it, it sounds like the main reason that
> a CD and a CDR can contain bit-identical data, yet still sound
> different, is the problem of jitter. CD players, especially
> cheaper ones, have more jitter problems w. CDRs, and even a small=20
> amount of
> jitter is perceptible. However, this is perhaps a problem that will be
> solved in the relatively near future, rendering the difference between=20=

> the
> two nil. Afterall, the problem boils down to this: 1) get a string of
> numbers from one disk 2) put the exact same string of numbers on=20
> another
> disk 3) deliver the exact same string of numbers to the D/A converters=20=

> of
> the sound system...This shouldn't be impossible...
> cheers,
> Michael
>
>
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