In the ten years since the company was founded, the name Audio Synthesis has become synonymous with achieving the highest quality sound from digital sources. To mark our tenth anniversary we have pulled out all the stops to create what we regard is our Masterpiece. The result is quite simply the finest converter ever produced by Audio Synthesis.
The direct connection
From our experience with the PASSION series of acclaimed passive attenuators, and of eliminating active stages wherever possible (to drastically reduce the corruption of the delicate audio signal) we know that the ultimate preamplifier is always no preamplifier.
For digital sources DAX DECADE is the perfect way to drive a power amplifier. It allows digital sources to be fully controlled in the digital domain without the need for external SPDIF interfaced boxes. The ultra high quality converter system within DAX DECADE then converts the selected level into analogue. The final analogue output signal is immaculately behaved and capable of a direct connection to any power amplifier over any choice of cable and without concern for potentially damaging operational transients which are expertly handled by intelligent muting. To offer such a direct connection we have carefully optimised the DAC and designed it to work at low output levels with extremely low noise and dc offset. Such low background noise level allows the use of more sensitive loudspeakers with an 8 ohm sensitivity figure in excess of 90dB/W/m if preferred.
Art in audio
DAX DECADE's enclosure is a work of high technology art. It is entirely constructed of grade selected aluminium chosen for its exceptional finishing qualities. CNC machining is programmed to create each of the six truly substantial chassis panels. These are repeatedly brushed to produce an extremely fine grain before being satin-black anodised.
And no expense has been spared on the front panel ......... machined from a one inch (25mm) thick bar of impurity-free aluminium, hand polished on five surfaces to a piano-black high gloss lustre before being deeply black anodised for long lasting protection. The complete enclosure ensures exceptional mechanical isolation from external vibrations, acts as an efficient total body heat sink and guarantees DAX DECADE will continue to look as good as it sounds for many years to come.
Operational Features
All the following features are standard, the only option being for digital domain, dual output differential fully balanced XLR analogue outputs, fitted in addition to the single-ended outputs. Coaxial RCA, Coaxial BNC, AES, ST wide band glass optical and Toslink plastic optical inputs.
Remote and front panel controls for: Attenuation in 1dB then 2dB and 3dB steps over a range of 96dB. Left to right balance control in 0.3 dB steps over a range of 40dB. Digital polarity invert. Silent and ramping Muting control. Display brightness. Four user selectable dither levels to eliminate small errors generated by the digital filter. Auto-Input facility. Custom naming of input sources. Sleep mode in Standby (including a remote control feed to TRANSCEND and DESIRE DECADE).
A total of 40 entirely separate and regulated supplies for digital, analogue and housekeeping sections. Critical mechanical suspensions for reduced audible distortion. Internal shielding for sensitive oscillators and analogue outputs. Named display indication for HDCD?decoding, polarity invert, disc error, initial locking and narrow bandwidth crystal locking and de-emphasis. A future-proof upgrade policy to guarantee compatibility with possible emerging digital formats.
Audiophile Engineering
In purely practical terms, DAX DECADE represents a commitment to excellence in design and engineering.
Based on 24 bit accurate data paths with 23 bit equivalent converter systems working to isochronous methods on multiple and fragmented ground planes for the ultimate in digital isolation from the delicate audio goal. A total of three toroidal transformers feeding 40 separately regulated supplies are used to power DAX DECADE and ensure real-world operation of the critical jitter eliminating circuits.
The handwired analogue stage is fully discrete, a single-ended class A current to voltage converter fabricated with exotic Vishay Bulk-Foil resistors and precision aligned pure silver and Teflon inductors. For easy bi-amping two pairs of WBT output sockets are fitted.
Time fades away
Both amplitude and time information is contained in the common SPDIF or AES digital audio signal. Digital audio typically suffers more from timing errors than from bit errors. Furthermore, the sound quality of a digital audio signal is greatly dependent upon errors in its timing (jitter or phase noise). The higher the resolution of the converters used, the more critical the requirement for a stable, interference-free clock to dictate the timing of the conversion process within the DAC. Poor reclocking in the DAC will result in phase modulation of the audio signal and a consequent `blurred' sound quality.
One of the most important design requirements for DAX DECADE has been the elimination of jitter from the conversion process. A great deal of knowledge and experience has been applied to the three phase locked loops within the clock recovery circuit and we are confident that DAX DECADE reduces timing errors to insignificant levels
Following input selection two PLLs are used to extract and purify the word clock. An electrically and mechanically isolated crystal oscillator forms part of a sophisticated second order PLL, tightly bandpass filtering the recovered clock before applying it to the digital filter and DACs. A third digital loop is used to isolate jitter generated in the digital filter - all DAC loading and sample & hold timing is derived from this third digital PLL.
Inputs are reclocked on multiple occasions before reaching the DAC itself. Low frequency jitter is the most difficult to eliminate so the three PLLs have been carefully optimised to boast a sub 1Hz jitter cut off frequency With the aid of multiple PLLs and intelligent muting we have made locking to jitter-ridden or off frequency transports routine, whilst maintaining automatic silent crystal locking for higher quality sources.
Performance
DAX DECADE produces music.
It produces music that's not only textured, rich, delicate and refined, but music that is capable of throwing caution to the wind and communicating with awesome dynamic expression. Seemingly without trying, it is able to recreate the acoustic of the recording venue and so set the scene, even before a single note has been played.
The music emerging from this acoustic has a genuine analogue nature which proceeds to coax you to relax into the performance and never to analyse the sound - a priceless and rare talent in this, our very processed world.
Jitter
The graph below shows a critical phase noise measurement made on the recovered clocks of the Crystal CS8412, UltraAnalog AES2O and DAX DECADE.
Sampling and analysis of the 256Fs clock was performed on a Rhodes & Schwarz FSA spectrum analyser, displaying in max hold mode with a span of 50kHz and a 500Hz bandwidth.
DAX DECADE clearly shows significantly lower jitter on its recovered clock.
Specifications
?2003 Audio Synthesis
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