the next wave in audio processing

Audonex's first product is the Sapphire, a high performance broadcast audio processor being developed from the ground up.

The Sapphire is a time coherent digital audio processor that fully conditions raw source material for competitive commercial FM broadcast. Time coherency — zero group delay — is a novel feature in a full-blown multiband processor, complicating the implementation of linear processing nodes, and placing additional demands on nonlinear processing nodes and distortion cancellation subsystems. But the payoff is clear to hear: palpable, absorbing immediacy and clarity, like that of the source material itself. The radical fidelity of the Sapphire engine (running in full five band limiter mode with 75µs preemphasis) is plain to see in the square wave plots at right.

Compared to the Sapphire, the ubiquitous mp3 codec conspicuously mangles the square wave, and the AAC codec (adapted by Ibiquity for “HD Radio”) shows somewhat more impulse overshoot and time domain ripple at “CD quality” 96kbps, and much more at the 64kbps commonly used for primary program in multiplexed IBOC broadcast applications. However, these comparisons are of course unfair, since the Sapphire is a complete signal conditioning processor with integrated baseband modulator, whereas the AAC and mp3 codecs are akin to the baseband modulator alone, and must be mated with a processor (the Sapphire, for example). Moreover, when the Sapphire is used to drive an FM exciter, there is none of the information loss associated with lossy digital codecs such as AAC and mp3. The Sapphire retains the vibrant immediacy of the source material in a way high ratio lossy codecs never do, and FM broadcast enables much more robust real world reception than does any terrestrial digital audio broadcast system. The FM broadcast preemphasis curve places limits on peak treble energy that digital distribution schemes avoid, but Sapphire's ultra-high-performance clipper infrastructure unearths treble headroom unimaginable a short time ago, yielding an open, natural, crisp, CD-like tonal balance.

State of the art broadcast processors are the most complex audio processors extant, and the Sapphire is no exception. 64 bit floating point precision is maintained through the entire processing pipeline, and the final sample rate is 960khz, eliminating peak overshoot. The Sapphire processor comprises hundreds of filters and nonlinear actuators, paradoxically all to create the most transparent, open, natural sound possible.

100hz square wave plots
Audonex Sapphire, 75µs stereo, process-mod-demod-deemph cycle
Audonex Sapphire, 75µs stereo, air check via Tandberg 3001A
64kbps AAC codec cycle
96kbps AAC codec cycle