Preamplifi ers and Input Signals 239It is, perhaps, signifi cant in this context that recent improvements in compact disc players
have all been concerned with an increase in the sampling rate, from 44.1 kHz to 88.2 kHz
or 176.4 kHz, to allow more gentle fi lter attenuation rates beyond the 20-kHz audio pass
band than that provided by the original 21-kHz “ brick wall ” fi lter.
The opinion of the audiophiles seems to be unanimous that such CD players, in which
the recorded signal is two or four times “ oversampled, ” which allows much more gentle
“ anti-aliasing ” fi lter slopes, have a much preferable HF response and also have a more
natural, and less prominent, high-frequency characteristic than that associated with some
earlier designs.
References .............................................................................................................
- Linsley Hood, J., Wireless World (July 1969).
- Livy, W. H., Wireless World , 29, (Jan. 1957).
- Baxandall, P. J., ‘Radio , TV, and audio reference book ’, Chap. 14, S.W. Amos, Ed.,
Newnes-Butterworth Ltd.