Mods to your External Dac

October 1, 2007

For this specific circuit to work, your DAC needs to use: (a) 11.2896 MHz clock, (b) 5V and (c) i2s input. Please don’t attempt to implement this specific circuit unless these conditions exist. Before attempting these mods, please build the reclocker board. Furthermore, my implementation entailed defeating the SPDIF signal that routed to my dac chip from my external DAC’s digital receiver CS8414. I also defeated power to the CS8414 by lifting two resistors on my DAC pcb. I do not cover these two mods below because every DAC is different.

1. Determine where to fit the reclocking board. It should be as close as possible to the Dac input pins. I mounted mine vertically.

2. You’ll need a power supply to the board. The voltage range is dictated by the Tent Shunt Regulator. The operating range is 2-6V above the 5V output of the Tent Shunt Regulator. So 7-11 Volt power supply.

3. I used Belden CAT5 shielded FEP cable to connect the reclocking board to the DAC input pins.

4. Examine the datasheet for your DAC chip to identify the input pins for BCK, LRCK and SDATA and SYSCLK if your dac uses this last one. Mine did not use SYSCLK. Depending on your dac chip you may or may not need the sysclko. If you do, examine the Board Layout, then just solder a wire to the 47R connected to the clock. Specifically, the wire would connect to the 47R lead that is also connected to pin 1 of the 04 chip (not the lead soldered to the output pin of the clock).

5. You’ll need to find a handy ground reference on your DAC pcb. Twist all three negative leads of the CAT5 together and tin the leads. Now solder this ground bundle to a ground reference.

6. You should terminate the positive leads through resistors instead of going directly to the DAC input pins. My Dac uses 10 ohm resistors here. That’s it!

To illustrate some of the above steps, there is a link to a diagram of my external Dac’s PCB. This shows the interface between the reclocking board and my Dac’s PCB. There are two TDA1541A dac chips.