D/A Converter Soulution 760 D/A Converter

Soulution 760 – reference D/A converter with Zero-Phase technology and dual power supplies

The 760 is a high-end D/A converter built on the principle of utmost fidelity to the source – it converts digital data into the analogue domain without taking anything away and without adding anything. Technically it builds on solutions proven in the 745 SACD player: high-quality digital input interfaces, a highly accurate clock generator suppressing jitter, intelligent digital processing with oversampling and Zero-Phase technology, analogue output stages on the level of a top-tier preamplifier, and a robust power supply. A digital volume control ranging from 0 to –79 dB in 1 dB steps allows a power amplifier to be connected directly, without a preamplifier.

The digital section is based on a powerful SHARC DSP, which performs 8× oversampling to 24 bit/352.8 kHz or 24 bit/384 kHz depending on the input signal. Instead of chasing extreme clock frequencies, the emphasis is placed on the precision of interpolation – an Anagram Technologies algorithm is used, followed by Burr-Brown converters in a digitally balanced configuration. PCM conversion is considered superior, which is why DSD signals are converted prior to the final conversion stage. The Burr-Brown chips work purely as converters; their internal upsampling and filters are not used. The output currents are converted to voltage in a conversion stage with an internal bandwidth of 80 MHz, which contributes to an exceptional signal-to-noise ratio and maximum dynamics.

The clock signal is provided by TCXO modules operating on the 3rd harmonic at around 100 MHz, developed with the focus on the lowest possible phase noise – which matters more to conversion quality than long-term frequency stability. A separate oscillator module is dedicated to the 44.1 kHz family and another to 48 kHz. Synchronising to an external clock would degrade performance, so the unit offers no clock input; instead, it allows other components to be synchronised via a BNC clock output. Zero-Phase technology eliminates the timing errors introduced by the analogue low-pass filter: a 3rd-order Bessel filter with a 120 kHz cut-off frequency shows a phase shift of up to 15° in the audio band, while after correction the phase error remains below 1° across 20 Hz – 100 kHz. The result is more precise localisation of instruments and voices, with clearly readable space around them.

The output stage uses an optimised circuit with special power transistors that are additionally linearised by an analogue computing network; the bandwidth reaches 40 MHz (–3 dB). Such response speed preserves micro-detail and contributes to three-dimensional imaging. The entire analogue section follows a consistent dual-mono concept. The power supply consists of two separate sources – one for the audio stages and one for the digital circuitry, with the audio section fed by an amplifier-like circuit design delivering an exceptionally stable output voltage and a capacitance of more than 500,000 µF, distributed without losses via bus bars. The converter is operated using buttons and a rotary control on the front panel, including functions for adapting it to the rest of the system.

Key features

• Zero-Phase technology: Phase error below 1° across 20 Hz – 100 kHz
• Oversampling: 8× oversampling via SHARC DSP and the Anagram algorithm
• Clock signal: TCXO on the 3rd harmonic with minimal phase noise
• Power supply: Two separate sources, capacitance over 500,000 µF
• Connectivity: AES/EBU, SPDIF, optical, USB and network up to 24 bit/384 kHz
• Volume control: Digital, 0 to –79 dB in 1 dB steps