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#1 Posted : Wednesday, April 14, 2021 2:11:47 PM(UTC)

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Hi all,

I was practicing with the layout of my new DAC and Cronus modules which needs to be interconnected with wires for the I2S transport.
Everywhere in the documentation I read not to exceed 10 cm of wire length for I2S wires.
Ideally we want to keep the wires as short as possible but I'm a bit afraid I have to use 11 cm wires minimum to interconnect the Cronus to the DAC. Is this very objectionable?

Also the balanced output is very close to the Pi which emits a lot of EMI. Any tips for shielding PCB connectors for instance?


Jordo IMG_5859.png (328kb) downloaded 4 time(s).

Edited by user Thursday, April 15, 2021 10:41:33 AM(UTC)  | Reason: Not specified

Brian Donegan  
#2 Posted : Wednesday, April 14, 2021 2:35:13 PM(UTC)
Brian Donegan

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There is nothing magic about 10cm, it is just a good guideline. The I2S clock lines (BitClock, MasterClock and LRClock) are all noisy lines, and can transmit noise to nearby power lines, and that noise tends to show up in the audio.

Here are the basics to follow:

1. Keep the I2S lines as short as you can
2. Keep I2S lines away from power leads. If you have to cross, do it at 90deg (shortest intersection possible)

Keeping the I2S lines all the exact same length is not a big deal either, but see above.

The balanced audio outputs should be able to reject any injected noise (the main benefit of balanced signals), but really depends on the construction of the input stage of the next component, and whether it takes advantage of the balanced signals correctly and cancels common-mode noise.

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Jordo on 4/14/2021(UTC)
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