The γ1 modular miniature DAC

The circuit boards

The γ1 DAC and USB circuit boards are made of high quality FR-4 glass epoxy, double-layer with plated-through holes as well as silkscreen and solder mask. The two boards are supplied as a single board set, with a center groove cut into the top and bottom sides, so they could be broken apart for the Hammond 1455C801 or 1455C802 enclosure, or kept as one piece for the Box Enclosures B2-080 series.

The board dimensions (after separation) are 1.9875" x 3.1375" (50.48mm x 79.69mm) and is 0.062" (1.58mm) thick.

Photos of the top and bottom side of the circuit boards are shown below. They are not in actual size.

The circuit board layouts are shown below. The top layer is shown in red, the bottom layer is in blue, areas where there are traces in both the top and bottom layers are in lavender, and the top silkscreen is in light grey.

The following is a view of the silkscreen layer.

You may also view the following:

The front and rear panels

Since all γ1 panel components are board-mounted, it is important that the holes on the front and rear panels be drilled accurately to match. The following diagrams and table shows the dimensions for the various γ1 configurations. All configurations shown below are for the Hammond 1455C80x series enclosure, except the "full++" (F) which uses the Box Enclosures B2-080 series.

For the USB-to-I²S converter configuration, the rear panel is identical to the USB-to-S/PDIF. But since there is no standard I²S connector, the front panel is not specified. Some uses of this configuration may be embedded in other applications without a Hammond case.

For the DAC-board only configuration, both panels are the same as the full-configuration except the USB connector at the rear is not used.

A2.1230" (53.924mm)
B0.9030" (22.936mm)
C0.1135" (2.8830mm)
D0.5929" (15.060mm)
E1.5301" (38.865mm)
F0.1085" (2.7559mm)
G0.0200" (0.5080mm)
H0.5051" (12.830mm)
I0.5445" (13.830mm)
J1.0565" (26.835mm)
K1.5815" (40.170mm)
L0.1400" (3.5560mm)
M0.1780" (4.5212mm)
N0.0350" (0.8890mm)
O1.0660" (27.077mm)
P0.5530" (14.046mm)
Q1.5655" (39.764mm)
AA4.2717" (108.50mm)
BB1.1614" (29.500mm)
CC1.8996" (48.250mm)
DD0.4606" (11.700mm)
EE0.3858" (9.8000mm)
FF1.5000" (38.100mm)
GG0.4875" (12.383mm)
HH0.5250" (13.335mm)
JJ1.4622" (37.140mm)
KK0.0106" (0.2692mm)
LL0.0656" (1.6662mm)
MM0.0629" (1.5977mm)
NN0.0656" (1.6662mm)
PP1.5514" (39.406mm)
QQ1.0000" (25.400mm)
RR0.4750" (12.065mm)
SS1.5125" (38.418mm)
TT0.0944" (2.3978mm)
UU0.1324" (3.3630mm)
Hole sizes (circular: D, rectangular: W x H)
Φa0.1600" (4.064mm), countersink cone diameter: 0.250" (6.35mm)
Φb0.1700" (4.318mm)
Φc0.2550" (6.477mm)
Φd0.1950" (4.953mm)
Φe0.3750" (9.525mm)
Φf0.3200" x 0.1650" (8.128mm x 4.191mm)
Φg0.4100" x 0.4100" (10.414mm x 10.414mm)
Φh0.1142" (2.900mm)
Φj0.1496" (3.800mm)
Corner radius
r0.1550" (3.937mm)
rr0.1181" (3.000mm)
Panel thickness
Hammond0.0591" (1.500mm) to 0.0787" (2.000mm)
Box Encl0.0787" (2.000mm)

The following PDF files may be printed 1:1 and used as drilling templates, but their accuracy depends on the resolution of your printer. You should use a good, calibrated digital caliper to verify all measurements.

Notes about the front and rear panels

You may use the listed dimensions to drill the panels provided with enclosure, or fabricate custom panels. If you use a Hammond 1455C801 case (with metal end panels), it is recommended that you discard the plastic bezels provided, and mount the panel directly to the case. The bezel pads the panel about 0.065" (1.65mm) away from the edge of the circuit board, causing the front 3.5mm stereo mini jacks to become recessed, possibly preventing the plugs from seating properly. It may also cause a Toslink connector from seating completely in the optical input or output module.

In the γ1, the case is connected to circuit ground via strips of exposed ground plane (along the sides of the circuit boards) against the case slots. If you have a metal front panel, you should make sure that the RCA jack's outer conductor is electrically isolated from the panel to avoid compromising the galvanic isolation provided by the coupling transformer, and deterioration of common-mode rejection ratio (CMRR). The hole diameter specified for the RCA jack is oversized for this reason.

For configurations where LEDU is populated, it should be mounted with its leads bent 90° and soldered on the board. Measure the the amount of needed lead length carefully prior to soldering, in order for the LED to fit properly in the panel hole. Only T-1 (3mm) should be used for the hole size listed above.

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