Johnny B Good wrote:

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Jim Lesurf wrote:

Interesting observation.

For some reason I always thought my first 14-bit Philips (CD104?)
sounded better than anything I had later, and that the one that I
bought to replace it some years later (16-bit parallel) also sounded
better. That machine now sits with a very elderly lady we know and I
will reclaim it when she passes. Comparison with my present Marantz
CD5400SE will be interesting.

The first player I had was the first gen Marantz using the 14-bit x4
Philips chipset. Happy with it for about a decade. Although I did add
some 'Toko' analogue low pass filters that rolled off at about 19 kHz as
that seemed to make the results sound nicer to my ears. Possibly because
it cut down the signal levels slightly going into the amp.


You seem to have forgotten that one of the benefits of 4x oversampling
eliminated the need for a brick wall anti-aliasing filter to allow a
filter with a much gentler roll off slope to be used which produced much
less in-band ripples in its response curve.


** Jim has not "forgotten" - impossible since it is not true.

The filter coming after D to A conversion is called a "reconstruction" filter and has nothing to do with aliasing.

The primary filter used by Philips in its dual DAC 14 x 4 players was a digital filter IC ( SAA7030 ) that created a high order LPF that still needed analogue filtering afterwards to reduce supersonic artefacts to tolerable levels. However, enough remained to prevent THD analysers reading the residual properly - hence very few reviewers could achieve the claimed 0.005%.

OTOH, Sony CD101s achieved 0.0006% THD using a spectrum analyser.
Later testing with a "dithered" disk showed no measureable harmonics.



The other thing about Philips's rather neat use of 4 times
oversampling with 14 bit DACs to achieve the same accuracy and dynamic
range of a perfect 16 bit DAC was the improved accuracy of monotonicity
over that of the typical consumer grade 16 bit DACs of the day. It really
was a very clever move on the part of Philips at the time.


**Philips used a 10 bit active plus 4 bit passive DAC ( TDA1540 ) which was not particularly linear. It was not near as good in those respects as the single 16 bit DAC used in early Sony players. In order to measure the linearity and THD of a Philips /Marantz player one needed to install a filter like to Toyo in the signal path.

I studied the topic carefully at the time and did my own testing too.


..... Phil