During our pursuit of sound quality to the extreme limit in the D/A converter unit, we discovered the impact of fine jitter generated within the DSP on sound quality. In the AZ-1, jitter within the DSP is eliminated by upsampling the audio data input from the DSP to the D/A converter at up to 192kHz and running the device asynchronously. The blind spots of the digital multisystem are resolved by the TI sampling rate converters in the dedicated tweeter, midwoofer, and woofer. Sound quality degradation is kept to a minimum through upsampling at frequencies up to 192kHz by using a highest echelon Cirrus Logic device on the external analog input signals.

In this design, the printed wire pattern of the analog audio circuit from the D/A converter output to the audio output terminal has completely isometric L/R length and the circuits for the tweeter, midwoofer, and subwoofer regions have completely identical patterns. The board lowers impedance to the extreme limit through a four-layer structure with an internal layer foil thickness of 70μm and a surface layer thickness of 35μm, and more specifically by use of 70μm wiring for the audio circuits and audio power circuits and by making all corners R-shaped. Through an exquisite design clearly delineated from mixed analog/digital systems, we have achieved high purity sound quality and an overwhelming sense of a high signal-to-noise ratio.

The audio system is equipped with high-efficiency, low energy consumption power circuits that maintain a complete separation between the audio and the video/control circuits. In particular, the audio system power has a fully discrete layout equipped with an independent, stable power supply employing audio regulator circuit technology, and circuit impedance is lowered to the extreme by inclusion of special acoustic parts. In addition to the focus on high efficiency and low current consumption, we have kept radiation and heat, which threaten sound quality, to a minimum.

Adopting an FIR filter in which phase rotation from filtering does not generally occur, the AZ-1 is equipped with an L/R, independent, 3-way digital processor that achieves ideal signal processing with no impact on sound quality and orientation even during crossover network and equalizer use. The equalizer has a cutoff slope of –12 to –300dB/oct. (–0.1dB per step), a time alignment of 0.77cm (0.02ms) steps, and a bit lossless negative control with 59-point selection (–0.1dB per step). Based on the outstanding tuning ability that typifies the equalizer and tuning operation* that employs Bewith’s unique SIEG^® in-vehicle acoustic measurement system, the AZ-1 boasts sound tuning previously not possible at a precision that approaches its theoretical value.

* Installation and tuning of this equipment is handled by exclusive sales outlets for Bewith products (SIEG^® equipment vendors). Sound tuning requires special equipment for measuring in-vehicle acoustics (SIEG^®) and special software, and cannot be done by the customer. Also, labor and other costs for installation and tuning are not included in the indicated product price.