DCAudioDIY.com

Seeking advice, since I'm a digital moron. Yes Roscoe, I know.

Have a DAC that I'm pretty pleased with and have plans to mod. I've added a balanced AES/EBU input, but would like to eliminate that interface and go straight from USB to the DAC.

Any guidance is appreciated.

Stuart

Take a look at this if you have an I2S Bus input available on the DAC board:

http://www.amanero.com/

Usually it is the interface between the CS8414 and the DAC chip. It can also be used with Native DSD files if the DAC supports it.

As HAL kind of alluded to, you're going to bypass the 8414 if you go USB. Depending on your DAC, the 8414 MAY be configured to output I2S to whatever filter/DAC chip is next in the signal chain in your particular DAC. In addition to the piece HAL linked to, there are a whole boatload of CM6631A based USB-> SPIDF/I2S boards on ebay for <$30 that'll work fine, for a little more an XMOS asynchronous converter may be slightly better in performance. If your DAC isn't DSD capable, the extra money for the amenero board may not be worth it.

Of course, if your 8414 is SMT & soldered to the board, it's gonna be tricky, but not impossible, to modify the DAC to take the I2S input.

Roscoe

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I can explain it to you, but I can’t understand it for you.

I have both CM6631 and XMOS USB to SPDIF converters I'm not currently using if you would like to try them.

Tom

Thanks for the input.

Tom, I'm going to pass on USB-S/PDIF. I have that now, would like to eliminate S/PDIF from the system.

Roscoe, HAL, if I understand correctly, the CS8414 serves to change the S/PDIF (in my case the balanced version) to the I2S protocol?

The DAC chips are BB PCM63. There are two other on board chips.

I don't have a super clear schematic. The DAC 60 is similar to my DAC 50, may be more legible.

Pictures are attached from when I replaced the Toslink input with a transformer, per Crystal's data sheet on the chip, to allow balanced input. Attaching both schematics. Will have to do multiple posts due to file attachment limits.






Does this help?

Stuart

This may be a bit more legible. But not exactly the same DAC. VERY close.

As Roscoe points out, the CS8414 would need to be removed from the DAC pc board and the I2S Bus lines used with any of the USB to I2S Bus conversion systems.

Here is a link to the datasheet if needed to see the I2S Bus pins.

http://www.futurlec.com/Others/CS8414.shtml

I have a DAC60 and it has DF1704/PCM1704 DAC's. Had mine moded and still works.

Looking at the DF1704 datasheet ( http://www.ti.com/lit/ds/symlink/df1704.pdf ), it looks like you might have issues with the XTI line on the DF1704, which is currently fed from the CS8414. Looks from the datasheet that the DF1704 can operate on it's own internal clock, but not at 96K. You'd need to change one or more control pins on the 1704 to make it run on it's own clock...

Roscoe

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I can explain it to you, but I can’t understand it for you.

Okay, the bulb is very dim, but it's starting to glow.

The I2S lines are pins 11, 12, 19 and 26. It appears that everything prior to that is associated with the 8414 and can safely be removed.

Ideally, I'd like to leave the S/PDIF and AES/EBU inputs in place and be able to switch between them and USB.

Can I simply cut traces, insert a switch or switch controlled reed relays, and add the USB/I2S interface?

It seems that several firms offer boards for this application, the Amanero one HAL linked to as well as Sonore and JL Sounds. The Sonore is a lot more money, but would be worth it if there is a big performance improvement.


Stuart