Arcam Delta 70

 The Arcam Delta 70 compact disc player has been designed to provide the best possible sound quality from compact disc digital audio. Together with the Arcam Delta 90, Delta 80 and the range of Arcam loudspeakers, the Delta 70 makes up the first complete CD based hi-fi system to be both designed and manufactured in great britain.

 Design Philosophy

Most specialist hi-fi companies merely "badge engineer" or modify mass produced Cd players, and are restricted to using their normal plastic chassis and standard circuit boards. From the outset, A&R Cambridge limited realised that this approach was simply not good enough to produce a Cd player to the standard demanded of an Arcam product. A&R therefore went to the trouble and expense of procuring full CD manufacturing licence. This gave our designers the opportunity to engineer the Delta 70 to a superior mechanical and electronic standard, incorporating much of the experience gained in producing some of the world's most acclaimed hi-fi amplifiers. Consequently, not only does the Delta 70 sound better, it is also visually more appealing and much easier to use than other CD players on the market.

 Versatility

Careful ergonomic design has simplified the operation of the Delta 70 to the extend that anyone can play a compact disc on it within a few seconds of first encountering the player. This is in marked contrast to many otherwise admirable CD players, whose complex control layout and over-elaborate displays frequently give rise to continued 'technofear', even amongst the most experienced users, let alone normal music lovers.

The controls on the front panel of the Delta 70 are divided into two groups. On the upper level they comprise just those needed to load, play and stop a compact disc. One the lower level we have included the pause button (conveniently located directly underneath the main stop button) and all the commonly needed programming functions. These include 3 speed search facilities and the previous and next track selection buttons, which will also access index points within a track. An easy to program memory is provided; this is capable of memorising the order of play of up to 20 different tracks.

To make operations even easier and more convenient the Delta 70 can be remote controlled using our optional infra-red remote control handset.

The displays on the Delta 70 have also been kept deliberately simple. An attractive and easy to read 4 digit fluorescent display provides readout of track and index numbers. It can also be used to indicate the total playing time of the disc and the elapsed time of each track as it is played.

Typical of the care and attention that our designers have taken is the location of the status indicator LEDs, which are provided for the power pause, and time/track functions. These are located just where they are needed, above the appropriate buttons, rather than buried elsewhere on the fascia.

Flexibility

The Delta 70's audio outputs are comprehensive, with both direct and variable outputs being provided. The latter is controlled via a low impedance ALPS potentiometer and is designed to feed a high quality power amplifier directly without the loss of quality associated with a conventional preamplifier. A headphones socket with adjustable output level is also included. This is driven from its own high quality amplifier, which has sufficient gain and power to drive almost any pair of moving coil headphones. Finally a digital output socket is fitted, for use with outboard D/A systems and for futur applictaions such as CD-ROM and CD-I.

 Electronic  Design

To recover as much information from the disc as possible the Delta 70 uses a swing arm single-beam laser pickup. This produces an inherently accurate signal from the disc than the 3-beam system used in most players. The disc playing mechanism is mounted on a fully floating sub-chassis to isolate it from external vibration. Allied to this is a 64K DRAM-based adaptive error correction system, which is one of the most comprehensive ever employed in a domestic Cd player. Taken together these features ensure the greatest possible integrity of recovered digital signal.

The digital signal is then processed using twin linear phase 120 element finite impulse response digital filters. These ultra stable low noise filters keep the audio band remerkably flat but dramatically attenuate the unwanted h.f. components of the audio signal. They are followed by dual 16 bit prcision DACs, operating in the classic four times oversampling mode at a frequency of 176,4 kHz. To enhance their timing linearity  (and hence sound quality) the Dacs are fed from a unique. A&R designed precision master oscillator.

Great care has been taken with all aspects of teh DAC and post-DAC filter and output circuitry to preserve this hard-won sound quality. Audiophile quality components been used throughout these stages, which have been assigned no less than five fully stabilised, critically decoupled power supplies. Integral withh the output filter which removes unwanted digital 'hash'. The circuitry is of an all-discrete transistor, direct coupled, class A design, which totally eliminates sound degrading interstage coupling capacitors from the signal path.

Specifications

Playback System:  16 bit , 4 x oversampling, dual DACs and class A direct coupled, discrete transistor analogue filter and output stages.

Optical Read-out System: 

Laser Type : Semiconductor Al Ga As

Numerical Aperture : 0,45

Wavelenght : 800 nm

Typical Audio performance (20 Hz - 20 kHz unless otherwise stated)

Frequency Response: 10 Hz - 10 kHz ±0,1 dB, -0,6 dB at 20 kHz

Channel Balance:  ±0,1 dB

Channel Phase balance ± 0,5 deg

THD:  0,007% at 1 kHz, 0 dB

Signal-to-Noise ratio:  101 dB unweighted; 105 dB CCIR/ARM weighted

Dynamic Range:  96 dB

Channel Separation:  100 dB at 1 kHz

Wow and Flutter:  Quartz precision control

Direct Outputs Level/Impedance:  2V RMS at MSB (0dB)/120 Ω

Miniumu Load Impedance:  5 k Ω

Variable Output Level/Impedance:  2V RMS, max at MSB (0dB)/1,25 k Ω max.

Headphone Output level/Impedance: 7V RMS max. At MSB (0dB)/ 250 Ω

Power Supply:  110, 120 220, 240 V AC 50/60 Hz

Power Consumption:  25 Watts

Dimensions (W x H x D):  430 x 90 x 270 mm

Weight:  4,5 kg net