Audio Receivers “Calculating” Stereo

[Brovidio]

I noticed this when looking at the pinout for Nintendo’s Multiout connector:



I interpret this to mean that Nintendo devices send Mono (L+R) audio out of the Left (white) RCA jack, and that stereo is deduced by the receiving device IF the Right (red) RCA jack is also connected.

This sounds too good to be true.
Can devices really do this?

I always thought Left was Left and Right was Right, and that if one was disconnected you’d lose everything on that side. I thought that if the console or game did not have a mono setting, I would have to merge the L&R channels externally for use on a mono TV, if I wanted to keep all the sound.

Is this pinout wrong?
Can devices actually calculate Stereo?
Should I have just let the Right RCA dangle and not worry about it all this time?

What am I missing here?

[nocash]

To my knowledge left is left, and right is right.
What are you talking about? Where did you find that pinout? Did you try to do a web search for "pinout for Nintendo’s Multiout connector"?

[TmEE]

There's no such thing going on on any game console output connectors. You do see such things internally in FM receivers and vinyl cartridges.

[Quietust]

I suppose it's possible that the Multi Out adapter could translate "L+R" and "L-R" into the separate "L" and "R" signals that stereo receivers actually need, though it would seem rather strange to do it that way when it'd be much cheaper to just use L and R separately from the beginning and require a Y-adapter for mono audio.

There seems to be a lot of conflicting information on what pins 11 and 12 really are - an article on pinouts.ru (which is linked from most web search results) claims that they are Mid+Side (as described above), while another page I found claims they are Left and Right, and the Super Famicom Development Wiki confusingly claims that both are correct...

[Brovidio]

Interesting article I found about Mid-Side audio.
I guess it’s something that was done a lot before the era of digital audio.

Still not sure what the implications are for the SNES.

https://www.sonible.com/blog/mid-side-processing/

[Brovidio]

I suppose it's possible that the Multi Out adapter could translate "L+R" and "L-R" into the separate "L" and "R" signals that stereo receivers actually need, though it would seem rather strange to do it that way when it'd be much cheaper to just use L and R separately from the beginning and require a Y-adapter for mono audio.

There seems to be a lot of conflicting information on what pins 11 and 12 really are - an article on pinouts.ru (which is linked from most web search results) claims that they are Mid+Side (as described above), while another page I found claims they are Left and Right, and the Super Famicom Development Wiki confusingly claims that both are correct...

That Nintendo article must have it backwards right? I would think you’d leave the RIGHT channel disconnected..

[lidnariq]

The installation manual that came with my SNES said that you should use a Y adapter if you had a TV with only one audio jack. I thought I remembered it saying that you could just use one side if you had to, but sound would be bad, but maybe they added that for a later console.

Certainly jwdonal's redrawn schematic shows it's L+R L & R.

[Pokun]

So that means connecting the left channel (white RCA) only would give you full mono sound and the Y-adapter is unnecessary?

And yeah red RCA is probably wrong. A SCART connector expects mono sound on the same pin as the left channel as well.

The US SNES manual has other mistakes. For example it says that controller 2 START and SELECT won't work, which simply isn't true. The Japanese SFC manual doesn't seem to mention this. The Japanese manual also doesn't mention a Y-adapter, and instead refers to the official mono cable SHVC-007.

[lidnariq]

So that means connecting the left channel (white RCA) only would give you full mono sound and the Y-adapter is unnecessary?

No. I meant "Left and Right" when I wrote "L+R", not "Left plus Right"

[Pokun]

I see thanks!