I realized I said "receiver" in my last post, but this is obviously a pre-amp/processor, with the XLR outs, and no internal power amps.
Speaking of power amps, that was a previous project which I never finished, because the PCM to PWM controlled amp chips I wanted to base it around materialized too late, and then with much lower specs than promised. But anyway, I was used to the power supply design for large devices. Where every Watt counts, and heat is can become a serious problem.
I started looking at power supply designs for the digital and analog stages in this device today. Even something as inefficient (but with very clean output) as a shunt regulated PS is feasible.
I'm narrowing down options now. But it looks like for the digital stage, I'll be using a transformer which can output 9 Volts from 115/230 AC, and then regulating that down to 5 Volts into the digital board. From there I'll be using very fine regulators to get the 3.3 and 1.2 Volt feeds where needed. The analog devices (basically just the DAC output, and opamps feeding the XLR jacks), will need a bipolar (+/-) PS ending up with just under 4 Volts. That has to be the absolutely cleanest power.
The system will be comprised of several boards. The DAC board I've talked about. Also the HDMI input board, which will connect to the motherboard, or DSP board mounted on the bottom of the chassis. The DSP board will connect over to the UI board which will provided the front panel controls. The DSP also outputs to the aforementioned DAC. The PS boards and transformers will be to the left and right of the DSP board (near the air vents in the sides of the case).
The DAC board will have 2 rows of 8 XLR jacks. I'm using vertical mount models, which would normally be facing up off the board. But instead the board will be vertical, parallel with the rear of the case. The XLR jacks themselves will be fastened to the back panel, so the solder joins will not be stressed on plugging or unplugging the cords.
The HDMI board will be above the DAC board. There'll be 5 HDMI ports, and 1 output. Similarly to how the XLR jacks were the mounting point of the DAC board, the HDMI jacks will be screwed to the back panel.
So I have basic ideas about the HDMI board, and only rough guess how the DSP board will go. The UI is still up in the air. Won't need too much, volume knob, menu/arrow/enter keys, input selector, and a display. I've not decided about an on screen display yet. That depends on how hard it is to encode into an HDMI compatible interface and format.
