Pooh Bear wrote
EddieM wrote:
Pooh Bear wrote



Ppl commonly make the mistake of associating such influences at the
time of listening with some kind of technology and then try to find all
manner of elaborate and totally wrong explanations for it. It's rarely
so.
There's normally some external influence going on.

So does the digital data gets 'picked-up' accurately through DAC by
recreating it or by copying it ?

The DAC doesn't 'pick up' anyrthing.


Yes, it is by the CD laser pick-up which then goes "through" DAC as I meant
to say.


The laser head in the player reads the digital data on the CD. Essentially
you
can consider a player as consisting of 2 functional parts.

The transport.....
This plays the disc and reads the digital audio ( and track ) data. It's
not
essential for digital data to be 'picked up' precisely accurately like it is
for
an analogue replay system since almost all digital data storage systems
including CD and hard disc drives use 'clever signal processing' to recreate
the
data including error correction and detection. CD recording 'encodes' the
audio
data using an error correction algorithm called 'Reed-Solomon' that adds
'extra
data' that enable the player to recognise and correct most data pickup
errors.
Really bad errors ( say caused by a defective CD ) are detected and
concealed
using a 'concealment algorithm' that 'makes a best guess' about a missing
sample.
Gross errors are muted.
It is possible that a really cheap and nasty player may be more prone to
error
issues.
It's a shame IMHO that CD players don't have a status LED indicating the
data
validity. DAT recorders that use similar technology often had status leds
that
indicated when the data was being corrected. Frequent error correction would
clearly indicate that the recovered audio wasn't perfect.
The player then passes the recovered digital data to the converter.


The converter.
This takes the digital data and converts it to analogue.
The quality of conversion will depend on the DAC chip, to some extent on the
following analogue circuitry and also any 'clever techniques' used such as
oversampling.
This is the area where the real audible differences are made. However, once
you
get past the 'economy models' there is frankly really quite little that
todays'
high end converters can do that a more 'middle of the road' one can't !
They've
really become that good.
As a final comment, as with all analogue circuitry, things like pcb layout
may
influence the final performance. This does offer some scope for the really
adept
designer to make a converter that excels over its peers, although I wonder
how
audible all of this is.


Graham


Alright ! Alright ! That looks like a lot of information but that's not
what I
had in mind wayy back then. Ahh Well those who might see that will really
like
it and will remember you and thank you (I hope).