NAD manual C520 CD Player, Circuitry

C520 CD Player

•Single disc CD Player with Full Function Remote Control

•Burr-Brown Sigma-Delta 20 bit Digital to Analog converter

•Coaxial Digital output • Low output impedance • Separate power regulators for analog and digital sections • Informative display with switchable track, time and repeat • Repeat mode for single track or entire CD • Random play • Remote control

Over the years NAD has built up an enviable reputation for building fine CD players offering outstanding value for money. The Model C520 will further enhance this reputation with its excellent performance and ease of use at a very keen price.

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 decep- tively modest front panel lies sophisticated circuitry.

Features RANDOM gives the listener a random selection of all tracks on the disc in play and REPEAT allows repeat playing of the disc or individual tracks. Individual tracks are easily accessed by SKIP (Forward and Back). SCAN (Forward and Back) gives an audio sampling of individual tracks, giving the listener the opportunity to reach specific sections of the track.

Using Electro-Luminescent back lighting, the display provides clear and understated yet comprehensive information to the listener. The track num- ber is displayed and for those who regularly transfer CDs to cassette tape, the button displays the current time elapsed or remaining for complete CDs or individual tracks. A "calendar" type section in the display gives immedi- ate visual information how many tracks in total there are on the CD.

The Model C520 comes supplied with a full function remote control, offer- ing all of the features described above from the comfort of your listening chair. On top of that, the remote control handset gives you direct track access as well.

Metal film resistors and polypropylene capacitors are used in key areas to ensure a highly accurate frequency response. Unusual at this price level, high quality 5532 op-amps are used instead of the much lower grade and type normally found at this price level and higher. Apart from the single output capacitor, no other capacitors are used in the signal path.

The output impedance is very low at 300 ohms, making the NAD C520 less sensitive to cables or the ancillary equipment it is partnered with.

Not all digital outputs are equal. In the case of the NAD C520 careful atten- tion 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 coaxial 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.

Truly excellent sound quality is difficult to find at this price, let alone with the added convenience of remote control. Anyone interested in a high per- formance CD player without frills should put the NAD C520 at the top of their shortlist.

Circuitry

Separate power regulators for the digital and analog sections isolate the two electrically, and furthermore, careful layout of the PCB tracks around the Digital-to Analog converter helps to contain RF interference.

For the NAD C520 the 20 bit high resolution Burr-Brown Sigma-Delta Digital-to-Analog converter chip was chosen for its excellent low level lin- earity and detail retrieving capabilities.