User manual

Pace-Car USB User Manual
Empirical Audio Rev. 1.0
1. Function/Technology
The Pace-Car USB is a versatile hi-res compatible USB interface combined with a
reclocker that can be used with an array of devices including various WiFi devices and
some CD transports. The object of the Pace-Car USB is to reduce jitter in the digital data
stream of streaming audio. Digital data goes into the Pace-Car USB and digital data
comes out, only with lower jitter. The Pace-Car USB incorporates our best low-jitter
technology and includes an array of technical advantages over other devices on the
market, including:
•
Galvanic isolation of all inputs to outputs
•
Async USB, so expensive USB cable is not necessary
•
External DC power source, allowing battery power
•
Separate input and output power regulation
•
High-quality discrete voltage regulation
•
Precision impedance-matched high slew-rate S/PDIF output
•
Optimum clocking for best 24/192 performance
•
I2S output interface for lowest jitter to Empirical Audio DACs
•
Modular design to allow for clock, power and USB improvements and upgrades
These technical advantages allow the Pace-Car USB to be a world-class digital source,
leaving even the most expensive CD transports and USB converters in the dust.
The sound of the Pace-Care USB is unlike any other digital source. The clarity and
imaging is unsurpassed, allowing you to “see” into the soundstage more than ever
before. Width and depth are improved significantly. It is a totally immersive experience,
the way that music playback should be. More like analog, only better.
1.1. What is jitter?
Jitter is the number one problem limiting the performance of digital audio. Jitter creates
an unnatural, harsh and sibilant sound that is pervasive in digital audio. Jitter causes
listening fatigue with both CD players and computer audio devices. It’s only in the last
three years that the audio industry has become sensitive to jitter and started actively
addressing this. The sound of jitter is like looking through a window with a film on it.
When jitter is reduced, it is like cleaning the window and finally seeing the scenery
outside with crystal clarity and vividness.
Jitter is the inaccuracy in the timing of the digital data. It is not data errors, it is
inaccuracies in the timing of the presentation of the data to the D/A converter. This is
different than sending digital data to a printer for instance, or even a hard-disk. These
data transfers are not “real-time”. Streaming audio data from a CD transport or a
computer source is real-time because the D/A converter creates a real-time analog signal
from the data each time a new data word is presented. If the timing of the presentation of
each word is inaccurate, this causes frequency modulation distortion. There is nothing
that can be done about the samples in the recording and the clock that was used to make
those samples, but playback jitter can be minimized. This is the role of the Pace-Car
USB.
The Pace-Car USB virtually eliminates the sibilance and harshness due to jitter, making
your digital playback closer to analog. The Pace-Car USB is a truly unique and
remarkable product. Once jitter is minimized, the clarity, image focus and dynamics are
improved significantly. Even bass-tightness improves. Recordings of rain, thunderstorms,
violins, cellos, bongos and timpani are finally lifelike.
1.2. Theory of Operation