Arcam Delta Black Box DAC

Here we have a very important piece of Hi-Fi audio history from former British company Arcam. In the early eighties digital music was first introduced in the form of the compact disc player and towards the end of the decade the Delta Black Box became the first available separate digital to analogue converter (DAC). Nowadays of course the technology has changed and improved somewhat but Arcam Black Box still has a great many fans around the globe. Our example is in fully working condition with a few signs of wear, as is to be expected – please see photographs. It will be carefully packaged and comes with manual, mains cable and our usual three month warranty.
Arcam Said….
The Arcam Delta Black Box is a mains powered, stand-alone hi-fi separate housed in a slim and elegant 430mm aluminium cabinet.
It is the world’s first affordable outboard digital to analogue converter designed specifically for CD players. It offers an elegantly simple and cost effective way of improving the sound quality of any CD player fitted with a digital output conforming to the Philips/Sony format.
In particular the Black Box is an ideal partner for the Arcam Delta 70 CD player. It provides existing and potential Delta 70 owners with a straightforward upgrade path, to take the performance of their unit even closer to the original source. Naturally the Delta Black Box is also a perfect match to our range of amplifiers and tuners, which it complements with both its stylish good looks and ease of operation.
The sound quality of a conventional one­ box CD player is ultimately limited by the sheer complexity of the transport system, with its mechanical drives and associated electronics. These are essential for the laser to ‘read’ the disc accurately, but the broadband electromagnetic interference created confuses the player’s sensitive signal converting stages (which are of necessity close by and fed from the same power supply system). The result is a blurred or harsh sound, with a loss of the subtleties and inner detail that help to make music enjoyable.
The Arcam Delta Black Box solves this problem at a stroke. It works with the signal from the digital output socket of a CD player and contains all the necessary components – oversampled digital filter, twin DACs, multiple power supplies and analogue output stages – needed to replay compact discs. Enthusiasts will know that it is the design and execution of these stages that is primarily responsible for determining the ultimate sound quality of CD in a hi-fi system. In the Delta Black Box not only are the circuits of absolutely first class quality, they are fully isolated from the mechanically and electronically noisy environment of the CD transport and display system. Because the interference from motors, servos and microprocessors is now eliminated, the DAC and analogue stages are able to work at their full potential.
For the reasons given above the sound quality of a two-box CD player utilising the Black Box will nearly always be superior to that of a stand-alone unit, in the same way that a good quality pre-amplifier and power amplifier combination is better than a comparable integrated amplifier.
Given a good quality CD transport and well recorded material, then the contribution of the Black Box to sound quality will be immediately audible. There are big gains in terms of resolution and detail. The individual instruments in a mix are more clearly separated, with more precise positioning in space, both in width and depth. Overall the bass is more solid, the mid-range more open and the treble clearer. The sound becomes more natural and involving. The listener is transported another step closer to the original performance!
The Arcam Delta Black Box will improve the sound of almost any CD player that has a coaxial (phono) digital output socket conforming to the Philips/Sony standard. Please note that if your CD player does not have such an output socket then you will not be able to use the Black Box with it.
It must be pointed out that the Black Box can only give of its very best if the associated CD transport mechanism is of the highest quality If the digital bit stream is not recovered properly from the disc it cannot be decoded properly! State of the art trackability (which implies good mechanical stability) and first class error correction are required, together with a
jitter-free master oscillator. These conditions are fully met by only a handful of players and it will come as no surprise that in our opinion the Arcam Delta 70 is amongst the best of these. We believe the combination of the Arcam Delta 70 and Black Box to be the best value two-box compact disc player on the market today.
Two audio outputs are available from the Black Box, both via gold plated phono sockets. In addition to the standard 2 Volt (rms) CD output we have provided an attenuated 800 mV line output suitable for the more sensitive /and often better sounding) inputs of many quality pre­ amplifiers and integrated amplifiers.
Both audio outputs are non-inverting (absolute phase correct); some commentators have noted that a number of discs have been recorded with absolute phase inversion and can sound better when phase-reversed. A convenient front panel
switch, which inverts the absolute phase of the signal in the digital domain, is provided on the Black Box to overcome this problem.
NB. In order to preserve the sonic integrity of the decoded signals, we strongly recommend that only first class interconnects are used between the Black Box and your amplifier. Interconnecting cables from the Arcam ‘Livewire’ range are particularly suitable.
Particularly notable in the design of the Black Box is the innovative use of an A&R designed and custom made ASIC
(application specific integrated circuit) for the digital processing of the input signal. This replaces some 25 standard CMOS chips which would otherwise be needed, with substantial improvements in power consumption, digitally radiated noise (and hence sound quality), reliability and costs. As far as we know no other suitable chip is at present available in Europe. We believe this to be the first genuine piece of custom silicon design carried out and put into production in a British made specialist hi-fi product. Others may talk about it, A&R did it!
The restored signal is fed to twin linear phase 120 element finite impulse response digital filters, operating in the classic four times oversampling mode. These ultra stable low noise filters keep the frequency response in the audio band remarkably flat but dramatically attenuate the unwanted high frequency components of the audio signal. They are followed by a specially selected TDA 1541A dual 16 bit precision DAC (digital to analogue converter). operating at l76.4kHz.
To minimise interference with the final analogue stages, all the digital processing circuits are fed from 5 separate regulated supplies and make use of their own dedicated power transformer.
Great care has been taken with all aspects of the DAC, integrator and analogue output stage design to give the best possible sound quality No integrated circuits are used in any part of the signal path, which features all class-A discrete transistor circuitry The DAC outputs are direct coupled to the audio output sockets, completely eliminating sound degrading interstage coupling capacitors from the signal path. We believe the combination of these two features to
be unique to A&R.
Audiophile quality components, including 1% metal film resistors, polypropylene and polycarbonate capacitors, are used exclusively in the post DAC stages, which are fed from their own fully regulated power supplies and separate power transformer. A new layout and star earthing arrangement is used on the glass fibre PCB to ensure minimum crosstalk and signal degradation.
Specifications:
Digital Section:
Digital input conforming to ‘Red Book’ Philips/Sony format
Phase-locked-loop master oscillator
Data processing in custom integrated circuit. Digital filtering and 4x oversampling dual DACs
Absolute phase reversal in digital domain, via front panel switch
Typical Audio Performance (20 Hz – 20 kHz unless otherwise stated):
Frequency Response: +/- 0.1 dB 10 Hz – 10 kHz, – 0.4 dB at 20 kHz
Channel Phase Balance: +/- 0.5°
THD: 0.015% @ 1 kHz 0 dB
Signal To Noise Ratio: 101 dB unweighted; 110 dB CCIR/ARM weighted. 110 dB IEC “A” weighted
Dynamic Range: 96 dB
Channel Separation: 100 dB at I kHz
Wow and Flutter: Negligible
Direct Outputs:
Output Level: 2 V rms at MSB (0 dB) (CD level)
Output Impedance: 30 ohms
Minimum Load Impedance: 5 kOhms
Line Outputs:
Output Level: 800 mV rms at MSB (0 dB) (Line level)
Output Impedance: 500 ohms
Minimum Load Impedance: 10 kOhms
Mains supply: Normally set to 220/240 V AC 50 to 60 Hz
Maximum Power Consumption: 24 VA
Dimensions: 430 (W) x 265 (D) x 64 (H) mm
Weight: 3.5 kg

To read a review from US magazine Stereophile please click here