Arcam Delta Black Box (1987)
An outboard D/A converter from Arcam’s pioneering Delta series, released in 1987 with a discrete analog stage and custom digital circuitry.
Overview
The Arcam Delta Black Box is an outboard D/A converter and digital audio processor introduced in 1987 as part of Arcam’s Delta series of hi-fi separates. Manufactured by Arcam (formerly A&R Cambridge), it was among the early commercial standalone DACs, reflecting the company’s push into high-end digital audio processing during the format’s infancy. The unit supports optical and coaxial digital inputs with 16-bit, 4x oversampling and handles sampling frequencies of 44.1 kHz and 48 kHz.
Specifications
| Digital inputs | Optical, Coaxial |
| Sampling frequency | 44.1 kHz, 48 kHz |
| Digital system | 16-bit, 4x oversampling |
| Frequency response | 10 Hz to 10 kHz ±0.1 dB, 20 kHz -0.4dB |
| Total harmonic distortion | 0.015% (1kHz) |
| Signal-to-noise ratio | 110 dB (IEC-A) |
| Analog output | Direct: 2Vrms/30 ohm, Line: 0.8Vrms/500 Ω |
| Power supply | 100 VAC, 50Hz/60Hz |
| Dimensions (W x H x D) | 430 x 64 x 265 mm |
| Weight | 3.5 kg |
Design
The Delta Black Box uses an Arcam custom IC and a specially selected Philips D/A converter IC. Its analog filter is fully discrete, and the audio stage is a direct-coupled, discrete component design operating in Class A with no op-amps in the signal path—visible op-amps serve only the DC servo circuit for offset control. The D/A converter board is mounted on a sorbothane vibration damper, and the entire case is constructed from aluminum. The power supply features an independent transformer and seven independent regulators for analog and digital circuits, with a star earth system to minimize noise. Reviews noted a slightly bright tonal character, described as "hot on the top end."
Context
Introduced in 1987, the Delta Black Box was part of Arcam’s Delta series, a line of high-fidelity separates developed during the 1980s. Arcam claims to have produced the first commercial outboard D/A processor, positioning this unit at the forefront of early digital audio innovation. It was reviewed in publications like Stereophile and compared to contemporaries such as the Musical Fidelity Digilog, remaining in enthusiast use well beyond its release.
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