The γ1 is almost the same size as a credit card, and
about 0.9" (23mm) thick. The diminutive dimensions makes
the DAC very portable and uses minimum desk/shelf space.
The extruded aluminum Hammond 1455C80x case, available in
black or silver anodized finishes, is attractive and sturdy.
The γ1 "full++" configuration uses the
extruded aluminum Box Enclosures B2-080 case, available in
a variety of colors.
Auto-sensing USB power or external power (via regulated 5V
AC-DC adapter).
The USB, digital and analog section power supply rails are each
independently regulated by separate high-performance Linear LDO
voltage regulators.
Ferrite beads and liberal use of decoupling capacitors further
assure clean, low-impedance supply rails.
Transformer coupling of coaxial S/PDIF input and output
for true galvanic isolation and improved CMRR -- usually found
only in top-tier pro-grade equipment (rarely in consumer-grade).
Analog output taken directly from the voltage-output Wolfson DAC --
no I/V stage or opamps.
The Wolfson DAC is operated in "high performance mode"
which increases its internal analog output stage bias, lowering
distortion and improving S/N ratio.
Big, high-end sonics from a tiny package -- the γ1 is
carefully designed for excellent performance, rivaling
DACs many times its size and cost.
Modular, Full-featured
The USB and DAC boards can be used independently or mated together for
the full feature set. Additionally, each board can be populated to
various configurations. This results in five main build options:
A: Full configuration
(USB board configured for S/PDIF format output, the DAC board
fully populated with coax and optical inputs, all inputs selectable
by front panel selector switch).
B: Lite configuration
(USB board configured for I²S format output,
no coax or optical S/PDIF inputs, no input selector switch).
C: USB-to-S/PDIF converter, no DAC board.
D: USB-to-I²S converter, no DAC board.
E: S/PDIF DAC only, no USB board
(coax and optical S/PDIF inputs, selectable by front panel switch).
F: Full++ configuration
(combination of A and C)
Integrated circuit complement
Some of these are optional depending on the desired build configuration
(also see the circuit description in the
Schematic diagram section).
Texas Intruments/Burr-Brown
PCM2707 -
USB interface and conversion to either S/PDIF or I²S
Cirrus Logic
CS8416 -
24-bit 192KHz S/PDIF input multiplexer and receiver, low-jitter
clock recovery and other functions
National Semiconductor
LP2985A-3.3, LP2985A-4.5
or Texas Intruments
TPS79333, TPS793475 -
LDO voltage regulators for independent USB section, DAC digital
and DAC analog supplies.
Texas Instruments
SN74AHC1G02 and
SN74AHC1G08 -
Logic gates for status LED control and USB D+ line pullup functions.
Designed to be easy to build
A specific target case, DC power jack, input and output jacks,
switch and other parts make this a highly integrated design.
All parts are through-hole except for the integrated circuits,
minimizing the number of SMD parts and making the γ1
easy to solder and assemble.
For the surface-mount chips, the widest pin-pitch parts were selected
where available, to make them easier to solder.
All parts are board-mounted, there are no wires to connect.
There are no trimpots to adjust after assembly.
All parts are easy to obtain (from AMB audio shop and from various
online vendors, see the Parts list section).
High quality circuit board
Both the USB and DAC boards are glass epoxy 3.1375"x1.9875"
printed circuit board, double-layer with plated-through holes,
silkscreen and solder mask.
The two boards are supplied as a panelized "board set",
grooved for easy separation into the two individual boards.
The layout of all parts and traces have been carefully
considered for maximum performance.
Double low-impedance ground planes are employed, with particular
attention paid to make the top layer ground plane as contiguous
as possible to minimize current loops.
A strip of the ground plane is exposed along each side (both top and
bottom), allowing the DAC's signal ground to be electrically connected
to the case (via the board slots) without the need to add any wires.
The grounded case improves RFI shielding without additional wiring.
The boards are designed to slide perfectly into a Hammond 1455C80x series
extruded enclosure, making the casing of this DAC very easy.
The γ1 "full++" configuration uses the Box Enclosures
B2-080 series extruded enclosure.
A 3D rendering of a partially-populated γ1 circuit board set.
