This is the situation:

I have built the following Opus DAC configurations:

1. WM8804 SPDIF receiver - Single Opus DAC configured for stereo per the manual - Ballsie Lite. This combination works and sounds great. I have used both Opus boards individually and both work in this configuration.
2. USB receiver - Dual Opus DAC configured for dual mono per the manual - Ballsie Lite. This combination works and sounds even better than the first.
3. WM8804 SPDIF receiver - Dual Opus DAC configured for dual mono per the manual - Ballsie Lite. Now this is the kicker, this combination just puts out noise (Static like crackling). I have checked and rechecked my work. There is continuity on the I2S header connections. There is continuity on the VD and VA power input headers driven by a LCDPS (One side for VD and the other for VA). VD = 7.5 V and VA = 7.5 V. I know that all the boards work! However, I can’t seem to make the SPDIF receiver - dual mono combination work while the USB receiver - dual mono combination work fabulously.

I will admit that I am perplexed.

I did not know where to post this: Opus vs WM8804 SPDIF. Therefore, I posted it to both threads. Sorry!

Any advice would be greatly appreciated.

My analysis thus far:

1. All boards actually work.
2. The SPDIF receiver board will work with the a single Opus DAC in stereo configuration.
2. The dual mono configuration will actually work with the USB receiver which is powered from the USB input.


This sort of leaves power supply or ground issues as the prime suspects causing the malfunction.

I will measure actual voltages at the Vd and Va headers of each board, as well as, the individual board current draws tonight after work.

If voltages are off, I have another LCDPS and a Placid module available.

If voltages are OK and individual board current draw is reasonable, I will try some experiments with additional grounding.

If anybody has any further ideas, feel free to jump in!

glt:

Thanks for the advice!

However, I have tried most things that I consider "low hanging fruit" to get the SPDIF - Dual Mono Opus up and running including setting the OSR switch to 0 (low), as well as, Z (open) which is the default setting. I have not tried the 1 (high) setting as the sampling frequency for most of my FLAC files is 44.1. The result is the same, no joy! However, I will also try the 1 (high) setting for OSR and post the results when I get home today.

glt:

OSR in position 1 (high)setting and it made no difference.

Now listening to Opus in dual mono via the USB receiver with default switch settings for dual mono per the manual. Fabulous, engaging, toe-tapping sound. Therefore, it is not the default switch settings on the Opus DACs.

Tried separate LCDPS for the 8804 SPDIF receiver next with default dual mono Opus switch settings. Got distorted sound from L channel only.

Very strange!

Will also try another SPDIF source from my Asus Xonar STX card.

OK - WM8804 SPDIF receiver to one Opus DAC configured as dual mono works for that channel. Similar to setting one Opus DAC to the stereo configuration (However, you get stereo output in this case).

BTW - Measured PVDD and DVDD at pins 7 and 19 of the the WM8804 chip are 3.29V each. Therefore the on board regulators are working.

Wanted to post a follow up to this thread.

It appears that the WM8804 SPDIF receiver has a personality disorder. It demands its own power supply or it acts out.

I tried to power Vd on both Opus boards and the 8804 SPDIF board from one side of a LCDPS with the Va on both Opus boards powered by the other side of the same LCDPS and had distortion in both channels. Reversion to a separate LCDPS to power the 8804 SPDIF receiver board resulted in the same fabulous sonics that I experienced last evening.

This observation largely supports my original thesis that the problem was in the power supply or the grounding scheme. It appears that it actually was. The dedicated power supply to the 8804 SPDIF receiver makes a huge difference in the sound and performance of this receiver.

Be advised that the WM8804 SPDIF receiver board needs special attention to its power supply to perform at its best. I suspect that this may actually be a problem with the chip itself or the design of the board. Looking at the schematic, there is not much to the board except power supply, HW control logic, the 8804 chip and I/O headers. The on board voltage regulators all measured at spec, therefore, I believe the problem is most likely the design or manufacture of the 8804 chip itself. Judging from the number of views of this thread in the last day, it would appear that others have had difficulty with this chip/board.