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Hello,
I am getting only silence from my S/PDIF transceiver connected to my Opus. I have tapped L+ and G and R+ and G to feed my amplifier. Please let me know any troubleshooting that I should do to resolve this issue or narrow it down to one of the boards.
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Just checked and S/PDIF is in the proper orientation, all pins lined up correctly, transceiver shows all green. I suspect the OPUS since I couldn't get it to work with an ebay usb to i2s last week. Edited by user Tuesday, March 27, 2012 6:51:08 PM(UTC)
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Some pictures will help us help you. :)
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  You can see the switch settings in these pictures although I took it apart and disconnected the wires to clean up my workspace. Power supplies sit at 7.1V.
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Those switch settings look okay. I guess power and I2S connections are next.
I2S should be straight forward...
BCK - BCK
SCK - MCK
LRCK - LRCK
DOUT - DIN
(if grounds are not already shared at the PSU)
GND - GND
How are you powering the two boards?
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I2S connections were correct - I checked continuity at the screw terminals and everything matched up straight across. I.e. terminal 1 beeped with 1, through terminal 5. I am powering the boards with three (2 for opus, 1 for S/PDIF) DIY power supplies, which consist of a capacitance multiplier operating at ~18V followed by a 8.2V zener reference at the base of a darlington. This gives ~7.1V at the power supply.
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Just set it up again for testing - the DAC just gives the staticky sound that is characteristic of RCA cables connected to nothing. In my setup, and maybe all, when RCA is connected to a live source the hum level is reduced and this doesn't happen when I plug the cables into the Opus.
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Since you are using just +out and GND, you have 2.5VDC offset on the outputs. It is possible your next stage does not like that. What is your source material (bitrate etc)? Edited by user Thursday, March 29, 2012 3:41:41 PM(UTC)
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The next stage is a B1 preamp, then Sympatico. I have tried without the preamp as well. Source is 44.1 KHz, 16 bit FLAC through my computer Realtek output or the USB converter mentioned in my email and forum post. Both are verified working to another source. I can't find a resampler that works in Foobar for 192 KHz.
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A small amount of extra noise (of square wave-ish character) is added when I start the source but it bears no relation to the music as far as I can tell.
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One more thing I just noticed: All of the pins on the I2S bus coming from the transceiver have 1.68V relative to ground except for the data pin, which has no offset at all. edit: when I play music it has a .9V DC offset relative to ground Edited by user Thursday, March 29, 2012 4:03:44 PM(UTC)
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Just got the foobar resampler to work at 192 KHz: you have to type in the rate manually. Still not working.
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Ok, I was checking to see if you were already using 192kHz, as this requires a switch change on the Opus, so we can ignore that.
Connecting directly to the Sympatico for testing will be a good idea, just to eliminate any possible offset issues.
Can you take a picture of the bottom of the Opus?
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 I would be curious to know about the change necessary to support 192 KHz. So far connected directly to sympatico: (close to silent) Noise at 44.1 Khz, faint music at 96 Khz, high pitched whine and faint music at 192 Khz. No difference between 16 and 24 bit output. Edited by user Thursday, March 29, 2012 5:19:55 PM(UTC)
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OSR set to 1 for 192kHz. Faint music is good.
Is it by chance the volume setting on the PC?
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The only volume I ever change is in Foobar and the faint music stays at the same volume regardless of the setting (except for all the way off which mutes it) -- this source works using an Asus Xonar Essence One DAC I borrowed. Edited by user Thursday, March 29, 2012 5:30:24 PM(UTC)
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If you are using the output caps on the Opus there should be no DC offset at all. Even if you only take one side of the balanced and GND.
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Are you powering VA nd VD from the same supply?
You capacitance multiplier may ramp up the voltage too slowly at start up. Try using a regular linear supply.
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It is often helpful to visually differentiate different signals with different color wire. For example green = ground, and red or black (or some other color) = some voltage or signal.
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VA and VD are different supplies with a common ground. The capacitance multiplier ramps up within a few seconds according to simulation and multimeter testing, as the most there is is a 47 ohm resistor between supply voltage and the capacitor.
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