Digital audio processors appear to be the major and, unfortunately, the essential component of a car audio system. This processor ensures carrying out compensation of the difference in distances from all the components of the audio system to the listener and the frequency division of different emitters’ bands, as well as the AFC correction (a car is not the most ideal place for listening to music). For this purpose the DSP should process the sound of several channels simultaneously performing millions of mathematical operations in real time. At the same time, the device obtains no margin for error; any failure would cause data corruption and, consequently, sound distortion.
That is why, we created a powerful and flexible audio processor for genuine music connoisseurs, from the beginning music lovers to the hard-headed audiophiles. Our solution is based upon the ADI manufactured fully programmable single-chip digital processor operating in the double precision mode, which ensures 56 bit internal calculations accuracy. In order to minimize the impact of rounding errors upon the sound, the processor processes the signal with the 96 kHz sampling frequency; and to ensure greater stability, we employ the master crystal thermal stabilization oscillator with the 20 ppm stability (almost all automotive processors obtain the clock accuracy of 100 ppm) and low jitter up to 1ps.
An important function of the processor ensures establishing connection with different sound sources. We propose three digital inputs with various interfaces and one analogue input providing easy integration within the car systems (navigation, hands-free communication / phone, etc.), which is 24/96 digitized. The digital inputs are organized using the high quality TI ASRC combo chips with the Jitter-cleaner function: THD + Noise - 125dB with the Lite version and -140dB with the Full and Audiophile Edition versions.
The DAC with balanced output is employed for accurate digital-to-analogue conversion (Full and Audiophile versions are using the current output), which ensures a wider dynamic range with less distortion. Single-chip 4-channel PCM4104 (118 dB Dynamic Range, 110 dB Channel Separation) in the Lite version, 2-channel PCM1794 (129 dB Dynamic Range, 123 dB Channel Separation) in the Full version (or PCM1795 32-bit analogue), the legendary BiCMOS Sign-Magnitude Burr-Brown PCM1702 (Dynamic Range >112dB) with the DF1706 digital filter (Passband Ripple: ±0.00005 dB) in the Audiophile Edition version.
|DAC||THD 0dB||THD -20dB||SNR|
|PCM1700||-88 dB||-74 dB||108 dB|
|PCM1702||-92 dB||-82 dB||120 dB|
|PCM1704||-92 dB||-83 dB||120 dB|
|PCM4104||-100dB||-84 dB||119 dB|
|PCM1794||-108dB||-98 dB||127 dB|
The analogue part consists of the Linear Phase Multiple Feedback filter of the symmetric topology third order. The use of such low-pass filters after the DAC ensures excellent pulse characteristics, as well as smooth phase-frequency variation and group propagation delay. The filters are employing the NPO/COG capacitors with ultra-stable dielectric, low temperature coefficient of capacity and 2% accuracy, as well as the metal-film resistors of 1% accuracy.
Regardless of the version, processors are assembled upon the high-tech four layer board of the 5th precision class using the FR4 material (industry standard obtaining better characteristics, than the FR2 material recommended for consumer electronics) with exit pads coated with immersion silver (ImmAg).
Audio processor could be controlled in two ways:
1) Using the SigmaStudio software delivered by the Analog Devices, Inc. (option for advanced users familiar with the microprocessors programming);
2) By means of the miniDSP 2x8/4x10 plug in (acquired separately). The settings simple and convenient native graphical interface plus the processor support the volume remote operational control using the variable resistor*; or volume control / input switching / presets selection could be carried out using the IR remote control* (processor is tuned to respond to commands from almost any remote control device).
* variable resistor and IR receiver are not included in the delivery set and are sold separately (specify completeness in the order).
By default, the processor firmware shall be updated to operate with the miniDSP plugin.
Also, any version could be delivered in the DIY (board in assembly) or Case (case with connectors) options.