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I have a sound system that has a TRS auxiliary input port, and I would like to connect a smartphone or tablet to it. I found out by experimenting that using a TRS-TRS setup will not do - contact was poor and more often than not I'd be losing signal there.

So I bought two cables, with the following characteristics:

  • One has a TRS male plug on one end, and two female RCA plugs on the other end;
  • The other cable has a male TRRS plug on one end, and three RCA male connectors on the other end.

My idea was to find out, by trial and error, which RCA connectors in the TRRS cable would take the left and right channels. I would then weld them to the RCA ends of the other cable and cut the remaining RCA connector off, which should carry either the mic or ground channel.

Experimenting with this setup, I found out that I know nothing about how these things work.

By connecting one channel at a time, I got two channels that would give a very faint signal, almost inaudible, and one that would give a weak signal to one of the stereo channels only. This was the red connector in the TRRS cable (it's red-white-yellow, with white in the middle).

By connecting two at a time, I found out that the yellow and white connectors together get very noisy and weak signal. Now this is where I was surprised: using both red and yellow or red and white gives me a clear signal, although not as powerful as I get when connecting a computer's sound output to the same sound system (using s TRS-TRS setup).

Even more surprising to me: by connecting the free male RCA connector to any of the two connected ones, I get a huge boost in power (though not in all frequencies). I realize this is just shorting out two channels, right?

So my questions proper are:

  • Why do both the yellow and white cables work just the same?
  • Will I eventually fry my cell phone/tablet if I keep shorting the cables like I mention above? I haven't tried it for more than a few seconds at a time.
  • Is there a smarter, more elegant way to achieve what I want, with the materials I have available?

I am not a native speaker of English and I know some terms I use here might be wrong. If so, please edit the question to make it more clear :)

P.S.: I don't know if this is relevant... I am using Samsumg devices (a SIII phone and a Galaxy Tab 2). I believe their pinout is different from Nokia and Apple devices, right?

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  • \$\begingroup\$ Perhaps a silly question: have you tried to look at the specification of the connectors? \$\endgroup\$ – clabacchio Feb 13 '14 at 18:29
  • \$\begingroup\$ @clabacchio I am completely clueless... The only thing that I found out was that, for my Samsung devices, the left and right channels should be the tip and its adjacent ring, with the other ring being the mic and the sleeve being the ground. I still don't understand how the mic channel and the right channel should be sending the same signal, and why shorting them boosts it. \$\endgroup\$ – Renan Feb 13 '14 at 19:08
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TRRS has a few standards. The iPhone/Apple Standard, the Nokia Standard, and a rarely seen video standard. They all mix where the ground is. Your adaptor may be any one of the three. Most important is the ground on the adaptor. The shield of the three rca connectors should be electronically connected to each other, AND it should go to the ring or sleeve that matches your source device.

AFAIK, Samsung has supposedly moved from the Nokia to the Apple standard, but that might not have been implemented on your specific model devices.

Apple Standard, TRRS = L, R, G, M.
Nokia Standard, TRRS = L, R, M, G.
Other Standard might have Ground where R normally is.

In any case break out a continuity or multimeter. Until you are sure the Device ground is connected to the rca shields, it won't work properly.

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