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512
Compact Disc Player
• MASH Digital to Analogue converter.
• Digital Output
• DC coupled output
• Low output impedance
• Separate power regulators for analogue and digital sections
• Remote control with direct track access
• NAD-Link
• Program (21 tracks), Repeat and Random functions
Over the years NAD has built up an enviable reputation for building fine CD players offering outstanding
value for money. Developed from the highly acclaimed and award winning NAD Model 502, the latest
model, the NAD 512 will further enhance that reputation.
As always, sonic performance is the first priority at NAD. Rather than adding many seldom used features
or going for "overkill" on a single aspect of the design, the NAD engineers have concentrated on the
design itself to offer the best performance possible at the price. Behind the deceptively modest front
panel lies sophisticated circuitry.
Features and Circuitry
Up to 21 tracks can be programmed in any sequence in the NAD's 512 memory, both from the front
panel and the supplied remote control. Repeat of the entire disc as well as any pre-selected track or the
programmed disc adds to the flexibility. The display incorporates a new "calendar" type, which gives
instant information on the number of tracks, time remaining or elapsed, and the track currently being
played. The RANDOM function will play the whole disc in random order.
Not all digital outputs are the same. In the case of the NAD 512 careful attention has been paid so that
best use can be made of the ever increasing number of products becoming available with digital inputs
(DAT, DCC, MD recorders, outboard D to A converters, etc.). The output is buffered and isolated by a
transformer from the converter itself and the output impedance has been carefully tailored to produce a
precise 75 impedance to ensure perfect matching. With the use of correct cables effects such as
reflections, overshoot and spurious signals will be eliminated the from NAD 512's digital output.
With advances in DAC technology coming so rapidly there is a tendency for manufacturers to copy the
"application notes" circuitry supplied with the Digital to Analogue converter chips. The end result is a
series of CD players of various brands differing only in the number of seldom used features bolted on.
This is not the case with NAD CD players.
For the NAD 512 a MASH Digital-to-Analogue single bit converter chip was chosen for its excellent low
level linearity. Instead of using a 4-pole filter in the analogue stage as is the norm with almost all other
CD players utilising a MASH D to A, a 5 pole filter is used, removing spurious RF interference more
effectively and keeping the audio band totally clean. Metal film resistors and polypropylene capacitors
are used in key areas to ensure a highly accurate frequency response. Capacitors are not used in the
signal path at the output (as this can degrade the sound quality).
The output impedance is very low at 120 , making the NAD 512 less sensitive to cables or the ancillary
equipment it is partnered with. The output itself is DC coupled (no capacitors are present in the audio
path). Any DC offset is canceled by servo circuitry constantly monitoring the output for any DC offset and
re-regulating it back to zero if necessary.
Anyone interested in a high performance CD player without frills should put the NAD 512 at the top of
their shortlist.