VOGONS


PCM Y cable

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First post, by ElBrunzy

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Maybe this is a stupid question and it's out of curiosity more than a need. I often read that people could use a Y cable to "mix" the output of 2 analog soundcards. It is not recommended but it can work, there is some risk associated with this practice too.

Similarly, I wonder what would append if one would mix two PCM (not dolby digital) output signal. I am not very familiar with this protocol but I assume some sync is sent time to time to inform the receiver of the bit depth and rate. So let say they are the same.

On my setup I have a sblive and awe32 both connected to different digital rca input of an onkyo tx-8140 receiver. Now, what would append if I cross the line and put both cards output with a Y cable on one input of the receiver?

  1. No sound or white noise.
  2. Perfect and crystal clear mixing of two sources
  3. Total flaming obliteration of my precious hardware

#1 is expected and #3 is why I dont try it. Any thought?

Reply 1 of 3, by derSammler

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You can not mix digital audio with a Y cable. I wouldn't recommend even trying it. Nothing bad will happen to the hardware, but the sound output may kill your speakers (or your ears at least 😉 ).

retro-net.de/blog.html

Reply 2 of 3, by Jepael

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My guess : no sound.

The receiver would not be able to see valid SPDIF stream.

Much like you can't split/mix any other ports like RS232, LPT, USB, VGA or Ethernet ports between three devices with a Y cable.

Reply 3 of 3, by ElBrunzy

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I think you are right, it will give no good. I've read this article about the format and spdif pcm format is way more controlled than I thought. I also did look at some picture of awe32 on the net and the spdif jumper seem to be directly connected to the chip with no protection whatsoever so chance that it break the circuitry are quite high.