New γ1 configuration possibility: Full++
By sanding down only about 0.015" (0.4mm) off each side, the γ1 PCB will fit perfectly into a
Box B2-080 series extruded aluminum case (without breaking the USB and the DAC portions apart). The result is the possibility of combining the Full configuration ("A") with the USB-to-S/PDIF converter ("C") in a single unit.
I'll call the new configuration "Full++". This gives you all three switch-selectable inputs (USB/coax/optical) and analog output of the standard "Full" configuration, plus coax and optical
outputs when the selector switch is set to the "USB" position. You can thus use γ1 to feed another DAC (or a computer sound card, or anything that accepts S/PDIF coax or optical inputs), all while the γ1's built-in DAC is also active.
To build this configuration, use the Box enclosure as specified (available from
Newark and
RS components, in various colors), and the combined parts list of the A and C configurations (see the
γ1 website). Where a part is listed as required for both configurations, you don't need to double the quantity. You can also omit R7U and LEDU, because the SW1D switch illumination already provides power-on indication.
All jumpers are set the same way as the standard Full config.
Obviously, since the γ1 USB and DAC boards aren't physically plugged into each other in this configuration, you need to connect the two sides with wires. A 5-wire ribbon cable is all that is needed. Connect as follows:
J2U pin 1 (VBUS) -> J4D pin 1
J2U pin 2 (VCC) -> J4D pin 2
J2U pin 3 (GND) -> J4D pin 3
J3U pin 1 (GND) -> J5D pin 1
J3U pin 5 (DATA) -> J5D pin 5
See picture below for an example of how I did this with the ribbon cable on the bottom of the board. I soldered the ribbon cable directly to the pads on the top side without the use of any pin headers or receptacles.
Pins 2, 3 and 4 of J3U and J5D are left unconnected because they are used for I²S in the Lite configuration ("B"), and are unused here.
Note that you cannot combine the Lite config with the USB-to-S/PDIF converter in a similar manner because the PCM2707 speaks I²S there, thus there is no S/PDIF output for coax or optical.
The Box B2-080 enclosure is larger than the Hammond 1455C80x, but still small enough to be called "very compact".
I didn't do this in my build, but due to more internal space and larger panels, this configuration also opens up the possibility of panel-mounting 75Ω BNC jacks for the coax input and output (please use isolated jacks), as well as RCA analog output jacks.
P.S. You can also use this casing solution for a standard Full ("A") or Lite ("B") config build. It will have no coax and optical outputs, but you may wish to do this for the panel-mounted jack options mentioned, or for the the extra case color choices. For the Lite config, you must use an 8-wire ribbon cable and connect all corresponding pads between J3U and J5D.
I don't have the panels done yet, but here are some pics showing the completed γ1 Full++ PCB and the Box B2-080 enclosure in silver.
