For starters, don't worry about taking power from one of the DAMs to power the s/pdif stuff. The power draw is so small that you couldn't possibly create an imbalance. Make your life simpler by using one of the DAM's power supplies.
Regarding the grounds, just make sure that all of the grounds have a single common point, for example the PSU connection.
Regarding the grounds, just make sure that all of the grounds have a single common point, for example the PSU connection.
I see.... But if I were to use an external PSU for SPDIF, would it be a problem that it's also used for the I2S isolation chip? Would noise in I2S leak into the signals via the common PSU?...
Actually you're totally right. Visual asymmetry does not imply meaningful imbalances. Curses of being an amateur... I'll just solder the 1.2V wire to one of the pads on the 1.2V trace and leave the LD1117 circuit disconnected.
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If you were to use a common PSU for the s/pdif section and the "dirty" side of the isolators you would effectively mostly cancel out the effect of the isolators since you would be bridging the dirty with the clean grounds.
That was the worry... I've since parted with that idea...
While I'm at it I'm finally getting an authentic Amanero to replace the Chinese replica - they're probably 99% alike but I don't trust the vendor enough and I don't know enough to take responsibility myself... plus you were right that only the real thing supports firmware updates. Also got CAT7 cable to transmit I2S more properly. Still using triple twisted and shielded wire for SPDIF though, seems reasonable enough.
At the moment I'm considering powering Amanero using low noise (relatively) regulated 5V 400mA from SK Lite. May be unnecessary but I have an extra pair of wires in the CAT7 cable so it doesn't seem too much extra trouble to make it happen. My plan is to only input data+/- and GND from USB and solder 5V/GND onto the Amanero USB PCB pins. Does this sound like a good idea? Thanks!
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Specifically, since I don't have space in my build for an intermediate connector before Amanero, I'll remove the 5V PCB pin on the USB type B socket on Amanero. With the help of some desoldering wick this should be feasible. This is better than customizing cables since it prevents damage to the devices should a regular cable be used by accident.
Good point... But I think the PC 5V is still coupled (?) to GND_USB via 4.7uF?... Mechanically it's also easier to solder the 5V and GND underneath the board close together at the USB socket. It would damage the socket but getting a new USB-B isn't that much harder or more expensive than replacing an unknown ferrite bead...
Hopefully the efforts to give Amanero more stable power does make it less likely for things to go wrong
If you're worried about noise coupling through the ceramic cap, you can also pull the cap out.
I would not mess with the USB socket. They are difficult to desolder without damaging the pads, especially if the board is 4-layer (the Amanero is not but still I would avoid it).
But that's just me.
I would not mess with the USB socket. They are difficult to desolder without damaging the pads, especially if the board is 4-layer (the Amanero is not but still I would avoid it).
But that's just me.
If you're worried about noise coupling through the ceramic cap, you can also pull the cap out.
I would not mess with the USB socket. They are difficult to desolder without damaging the pads, especially if the board is 4-layer (the Amanero is not but still I would avoid it).
But that's just me.
I'm a computer science person and I honestly don't like messing with even semi-expensive boards... but I feel like I'd rather keep SMD components intact for some reason. USB socket is really cheap, easy to find and hard to go wrong. I share your worry of damaging the board during desoldering as I haven't had the easiest time removing solder in general. But there was this YouTube video of a girl who successfully replaced the USB socket on her device with a soldering iron that she just bought... It's quite reassuring I tell you...
Maybe you meant something more specific with damaging the pads. If Amanero isn't tin-plated it should be feasible no?... If it works it would be a very clean solution...
Looking for some clarification on I2S input connections for Soekris 1021. Planning to use it with XMOS 384kHz DXD DSD256 high-quality USB to I2S/DSD/SPDIF PCB - DIYINHK
Using separate PSU with 5VDC for USB to I2S interface. Is it OK to just connect directly from DIYINHK board 3.3V connections to DAC ISO 3.3V J3?
Using separate PSU with 5VDC for USB to I2S interface. Is it OK to just connect directly from DIYINHK board 3.3V connections to DAC ISO 3.3V J3?
Follow the User guide:1. External regulated 3.3V power supply is connected to the 20pin header pins label 3.3vINx2
So no 5V PSU, try 3.3V and also use the 3.3V for DAC ISO 3.3V J3
Regards
Torsten
Thanks Torsten ! I guess my question was if I can re-use same 3.3V PSU for both XMOS module and DAC?
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