| The D1 has been designed as a state-of-the-art
standalone converter using new proprietary circuitry and the finest components available
to deliver the most musically precise interpretation of the digital data stream possible.
The input system offers AT&T, AES/EBU, SPDIF, and Toslink inputs.
The receiver system a special phase lock that removes the jitter and
clocks the digital filter and DAC with about 35 pS of jitter. Eight times oversampling is
provided by an NPC digital filter with 32 bits internal and 24 bits external precision.
Four matched Burr Brown PCM-63 (K) D/A Converters operate in a fully balanced
configuration to minimize distortion and noise.
The output of the D/A converters is fed to the most dramatically
innovative current/voltage (I/V) conversion stage in the industry. The circuit converts
the current source output of the DAC chips to output voltage with a single gain device
operated in single-ended Class A mode without signal inversion and without any negative
feedback. This simple no-feedback approach gives the superlative objective performance of
op-amp type circuits but is completely immune to the RF transients emitted by digital
circuitry and spends no effort processing high frequency noise in feedback loops. The
result is sound completely free of the high frequency artifacts caused by op-amps meeting
digital circuits.
The D1 has two separate toroidal power transformers, one low
voltage/high current for digital circuitry and the other high voltage/low current for the
analog stage. The power supplied for each section of circuitry use up to four separate
active and passive power supply regulators and filters to assure total isolation between
the digital and analog functions.
The DAC weighs 35 lbs and is 17" wide, 3.5" tall with the
feet, and 11.5" deep. The face plate is finished light instrument gray anodize.
The PASS D1 DAC was engineered through listening tests over a period of
time in competition with the most highly regarded DAC's on the market. Changes in the
design were based on listening experience, and correlated with measurements. The sound is
lush and smooth, with a wide sound stage, fine detail and layering, and a nice firm
bottom. |
