Proceed CDD - Manual (Page 10)

10
Special Design Features
Congratulations on your purchase of the CDD Compact Disc Drive. The Madrigal
design team is confident you will enjoy the outstanding performance of the CDD
for many years. In case you are interested in technical details, what follows is a
brief outline of some of the key technologies in your new transport.
A New Generation The characteristics of an outstanding CD transport are simple to define: it must
recover the correct data from the disc, and deliver it to the digital processor with-
out any timing errors (sometimes called “jitter”). As simple as this sounds, achiev-
ing it in reality has been extremely difficult—as evidenced by the significant
sonic differences between various CD transports.
Conventional CD transport design depends on the quality of the oscillator used
to control the rate at which the disc itself spins. This oscillator exists in an ex-
tremely “noisy” electrical environment close to the motor that spins the disc. The
electrical noise introduces timing errors in the delivery of the digital signal that
have come to be known as “jitter.” Subsequent handling of the digital audio sig-
nal in traditional transport designs cannot improve upon this “jittery” signal, lack-
ing a better reference. To the contrary, the various stages of signal processing be-
tween the laser pickup and the final output can only contribute additional jitter of
their own.
The Proceed CDD leaps beyond conventional digital audio technology by em-
ploying a proprietary, closed-loop jitter-reduction system in conjunction with a
double speed
CD - ROM drive. Using a custom-made crystal oscillator with better
than five part-per-million accuracy, the digital signal is reclocked immediately be-
fore the output, eliminating transport-related jitter from the digital audio signal.
This same crystal oscillator controls the all-digital servo used to control the rate
at which the disc spins.
In effect, the design of the CDD turns the accepted status quo on its head. By
placing the all-important reference clock in the final stage of the transport’s out-
put section, and slaving the mechanical subassemblies to it rather than the other
way around, the signal presented to the outputs of the CDD is uncontaminated
by electrically- or mechanically-induced jitter. The sonic advantages of this design
are immediately apparent in the clarity, warmth and stunning dynamic contrasts
exhibited by the CDD.
Digital Servo Control The laser mechanism used in the CDD uses all digital servo controls of its opera-
tions. Critical functions such as focus and tracking are handled completely in the
digital domain with mathematical precision. Whereas conventional, analog servos
require periodic realignments for optimum performance (to compensate for the
aging of various analog components), a digital servo remains stable over time,
never needing readjustment under normal conditions.
Output Versatility All high quality digital output configurations are supported in the CDD. A new
complementary driver for the balanced AES/EBU electrical output delivers out-
standing performance to the high quality XLR connector. Single-ended S/PDIF
electrical outputs are provided via both BNC and RCA connectors, and the
optional ST optical output uses a high-bandwidth Hewlett Packard
® part for supe-