Prism Sound AD-124 was introduced in the early 1990s as a professional standalone analogue-to-digital converter aimed at studios and mastering facilities where accuracy and flexibility were essential. It combined very high dynamic range with advanced processing options to deliver transparent A/D conversion and to preserve as much of the original performance as possible through word-length reduction and noise-shaping methods. Its robust design, range of formats and compatibility with both professional and consumer digital systems made it a respected choice for high-end recording, broadcast and mastering work.
The Prism Sound AD-124’s analogue input stage uses transformerless, electronically balanced and fully floating circuitry to minimise noise pick-up and crosstalk. High-resolution converters require careful analogue design so that the benefits of extended dynamic range and lower distortion are not lost before digitisation. With an impressive dynamic range of 118 dB, the AD-124 allowed engineers to set generous headroom while keeping low-level noise and distortion well below perceptible thresholds. Synchronous digital logic and digital DC elimination helped avoid editing artefacts such as thumps or clicks.
Prism Sound recognised that extended resolution in a recording is only valuable if it can be faithfully delivered to the final listening medium such as a standard 16-bit CD. To address this, the Prism Sound AD-124 offered four selectable Super Noise Shaping curves. These curves provide superior low-level performance compared with standard TPDF dither when reducing high-resolution recordings to 16 or 20 bit formats.
The Super Noise Shaped output remains fully compatible with all existing digital-to-analogue converters, both consumer and professional. Additionally, the unit supported Prism Sound’s DRE (Dynamic Range Enhanced) coding allowing near 24-bit quality to be stored on 16-bit media such as DAT without track count loss, with corresponding decoding available on playback.
Digital connectivity on the Prism Sound AD-124 covered professional and consumer standards. Simultaneous AES3 and S/PDIF outputs were provided, with optional SDIF-2 support for digital interfacing to workstations and multitrack recorders. The converter could operate with its own internal crystal oscillator or be locked to a variety of external reference sources via AES11, word clock or optical input to ensure stable synchronisation at 44.1 kHz or 48 kHz.
Throughout its production life the Prism Sound AD-124 was widely adopted by recording engineers, mastering specialists and broadcast facilities that demanded both musical integrity and technical precision. While newer multi-channel and higher sample-rate converters have succeeded it, the AD-124 remains notable for popularising practical noise-shaping techniques and for its role in bringing high-resolution conversion into professional workflows.
Features
- Professional standalone analogue-to-digital converter
- Transformerless, electronically balanced, fully floating analogue inputs
- Four selectable Super Noise Shaping curves for improved low-level performance
- DRE coding and decoding for extended dynamic range on 16-bit media
- Simultaneous AES3 and S/PDIF outputs
- Optional SDIF-2 digital output available
- Support for format conversion and D-to-D modes
- Internal or external reference sync via AES11 or word clock