What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

Marantz CD-94

With the partnership of the CD-94 Compact Disc Player and CDA-94 Digital-to-Analogue Converter, Marantz presents true digital audio equipment for audiopfiles. Equipment dedicated to the digital audio requirements of today and tomorrow. Both incorporate two Marntz features which add to the fidelity of the reproduced sound: 16-bit D/A conversion with 4 times oversampling and optical coupling.

The superb audiophile performance of the CD-94 is based on the proven superiority of the Marantz full 16-bit 4-times oversampling digital filter, it is characterized by very low distortion and almost no phase error.

The digital filter is employed in conjunction with the improved 16-bit dual Digital-to-Analogue converter TDA-1541A. This VLSI (Very Large Scale Integrated circuit) delivers greatly improved channel balance, flatter frequency response and at least % dB higher dynamic range, than previous IC's.

The combination of digital filtering and dual digital-to-analogue conversion result in the enormous dynamic range of 104 dB, coupled with extremely fast transient response and very high phase linearity.

A vital factor in the performance of the CD-94 is accurate read-out of the disc. The CDM-1 mechanism, made of diecast aluminium, provides rigid support for the laser pick-up. The complete assembly is floated off the main chassis on massive rubber dampers; a suspension system that assures freedom from vibration and acoustic feedback. Furthermore, the mechanical control circuits have been separated from the CDM-1 mechanism to avoid magnetic interference in the control circuitry and possible vibration from the drive mechanism.

The main chassis and the top cover plate are also diecast in non magnetic aluminium. They are designed to reduce distortion caused by acoustic feedback and eddy current coupling. The rear plate, and all of the screws used on the inside are copper plated for the same reason.

At the rear,the black heat sink is carefully damped to avoid any ringing that might be caused by internal resonance. Thus, vibration in one power transistor does not disturb the current flow in another.

The high VA power transformer has four independent secondary windings; one each for:

- the mechanical control system

- the digital signalprocessing circuits

- the analogue signal processing circuits

- the displey circuits

This prevents peak demand inone circuit from causing performance degrading power drain in another. And it also reduces the possibility of one power supply causing interference to another.

50 Hz mains hum is audible but it is not music. To suppress it, mains wiring is kept to one corner of the chassis. Even the power on switch is mounted in that corner and operated through a long polycarbonate rod.

Carefully chosen customized components guarantee the highest achievable sound quality. In addition to the high-VA power transformer, noteworthy components include high value ELNA electrolytic capacitors in the Bessel filter stages. The capacitor leades are of tinned oxygen-free copper, not the usual tinned steel. Everything possible has been done to ensure the quality of the sound signal at the gold-plated output terminals. All the complex functions of signal decoding and error correction are concentrated in one single VLSI chip. This is specially designed to take full advantage of the powerful error detection and correction code offered by the Compact Disc digital Audio system, but only partially used in many players.

With its digital output facilites the CD-94 can be directly connected to other digital signal processors, including the CDA-94 Digital-to Analogue converter. A standard 75 ohm electronic output is provided. But for the best possible transmission, optical output coupler is fitted. The high-precision disc tray loading has separate motors for tray drive and disc positioning with magnetic clamping to ensure stability during rotation.

The FTS (Favourite Track Selection) memory stores preselected track numbers or timed passages from a complete Compact Disc collection. Once the favourite tracks on a particular disc have been stored they can be played at any time without the need for any further programming (although the celection can be changed at any time). The exact number of disc that can be programmed depends on the programmes chosen. As an example 155 discs can be programmed to play an average of 5 tracks per disc.

Fully remotely controlled, the CD-94 has lacquered wooden sides, a discretely elegant display and goldplated keypad buttons. A flip-down cover conceals all except the principal front panel controls until they are needed. The display is clear, without being disturbing. The styling is classical Marantz, distinguished and refined.

Specifications for the Marantz CD-94

Audio Characteristics

Number of channels: 2

Frequency response: 2 - 20.000 Hz ±0.1 dB

Digital to analogue conversion: 16 bit 4 times oversampling

Dynamic range: better than 96 dB

Signal to noise ratio: 101 dB

Channel separation: Better than 100 dB (1000 Hz)

Total harmonic distortion: 0.0015% (1000 Hz)

Wow & Flutter: Unmeasurable (quartz accuracy

Error correction system: CIRC

Audio output level: 2 Vrms

Optical Data Read System

Laser: AlGaAs semiconductor laser

Wave length: 780 nm

Signal format

Smapling frequency: 44.1 kHz

Qunatization: 16-bit linear/channel

Power supply Section

Power requirements: 220/240 V AC, 50/60 Hz

Power consumption: Approx. 30 W

Fuse capacitance: 0.2 A

Cabinet and Others:

Dimensions (W x H x D): 462 x 86 x 333 mm

Weight: Approx: 10 kg

Compact discs

Diameter of disc: 120 mm

Thickness: 1.2 mm

Rotating direction: counterclockwise (viewed from the laser pickup side)

Scanning velocity: 1.2 - 1.4 m/sec

Revolution (spindle) speed: 500 - 200 rpm

Playing time (theoretical): 74 minutes max. (stereo)

Track pitch: 1.6 um

Material: Plastic (polycarbonate)

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