Dreamcast with Digital Audio output SPDIF or COAXIAL

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rpf16rj
lithium
Posts: 37
Location: Brazil
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Dreamcast with Digital Audio output SPDIF or COAXIAL

Post by rpf16rj »

Hi guys, how are you? I hope good.

Recently I discovered a mod that allows the Dreamcast to have a digital audio output.
Literally, the Dreamcast already has an Audio Digital to Analogic converter for output audio, but has some noises and the quality is not the best. In cooperation with digital audio quality, the sound of Dreamcast is amazing.
Here is an example:
https://www.youtube.com/watch?v=9Yn2sUN_C1E

The mod consists of getting digital data and clock signal from Dreamcast DAC CI PCM1725U and using the CI Cirrus CS8406 to convert to digital output that any receiver with digital audio input recognizes.
The tutorial for the mod is here and should work with some consoles like Saturn, and SNES...
https://www.elotrolado.net/wiki/Salida_ ... ital_SPDIF
and this https://gamesx.com/wiki/doku.php?id=av:dreamcastda

I'm trying to install this on my Dreamcast, but this doesn't work. My receiver recognizes digital signals but does not have sound.
On this tutorial have a note about the EMPHASE signal from Dreamcast PCM1725U, the author says that for Dreamcast the EMPHASE pin needs a logic converter but doesn't show more details about this.
I found in another link some information about using a hex inverter like 7404. I did try using a 74hc04 that appears to be equal by datasheet info, but without success.

I suspect that this mod is wrong or never worked and the videos on YouTube are fake... but analyzing the datasheet of both CIs, shows is possible.

Another video demonstrating the installation of this mod in an SNES and showing work:
https://www.youtube.com/watch?v=BqRy5WtFgt4
And this in a Sega Saturn:
https://www.youtube.com/watch?v=BEKLsyjYrbQ

My doubt is somebody already did this mod and has more information on whether it works or not on Dreamcast.
Already spend some money by bouth a lot CS8406 CIs, guessing that have some problem with it, but not.
Curious tester of old games and software and electronic modder sometimes.

Youtube channel: https://www.youtube.com/@rpf16rj1

User avatar
rpf16rj
lithium
Posts: 37
Location: Brazil
Contact:

Re: Dreamcast with Digital Audio output SPDIF or COAXIAL

Post by rpf16rj »

Finally, I get worked!
As I bought 2 pieces of CI, I soldered again with another CI and put a capacitor 100nf between 5V and GND.

I record a video demonstrating, it in Portuguese, please turn on the subtitles.


Here an comparation captured.
Curious tester of old games and software and electronic modder sometimes.

Youtube channel: https://www.youtube.com/@rpf16rj1