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Suppose one has a stereo audio source with a single 3.5mm stereo output jack, and one wants to split the left and right channels so that each is produced on one of two powered (i.e. self-amplified) stereo speakers, each of which has a single 3.5mm stereo input jack — the intention being for each of the two stereo speakers to play its assigned mono channel on both of its own output channels, as if the input were balanced mono. Symbolically, this might be represented as {LR}→{LL+RR}. What would be the most straightforward way of accomplishing this?

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  • \$\begingroup\$ I guess you could use a TRS->2×TS adapter followed by a pair of TS->2×TS splitters? \$\endgroup\$ – Hearth May 10 '18 at 21:54
  • \$\begingroup\$ Why not use a splitter with {LR+LR}? Splitter = 1 to 2 way adapter or a "ménage à trois" connector \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 10 '18 at 21:55
  • \$\begingroup\$ @Felthry ...further followed by a pair of 2×TS→TRS adapters? Argh, I was hoping for something more elegant. \$\endgroup\$ – jdmc May 10 '18 at 21:56
  • \$\begingroup\$ If you need them in TRS connectors, then, yes. But if you want to do some wiring of your own, you should be able to get a couple TRS jacks and cross some wires between them. \$\endgroup\$ – Hearth May 10 '18 at 21:57
  • \$\begingroup\$ @TonyStewartolderthandirt Because that would defeat the purpose of having a stereo source to begin with. The objective is to position the two stereo amps at a distance from each other so as to maintain stereo separation of the original signal. \$\endgroup\$ – jdmc May 10 '18 at 21:57
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For line-level audio (or approximately-line-level as in "headphone jacks") connections you can just split an output with wires and connect it to multiple inputs. To achieve any particular audio channel mapping you would like, you only need to make the corresponding connections between the TRS connectors' (T)ip and (R)ing contacts, and connect all the (S)leeves together.

For what I understand you want:

schematic

simulate this circuit – Schematic created using CircuitLab

(Using boxes for the connectors because CircuitLab doesn't have a more appropriate symbol.)

If instead of wiring you want to use commonly available audio adapters in a not too messy fashion, I would suggest the following parts:

  • 1× TRS to pair of RCA (this can be found in both rigid adapter and Y-cable forms)
  • 2× RCA to TRS (example, not a recommendation as I've had very mixed luck with this manufacturer's adapters but I don't have a better one)

Less esoteric than the second item would be to use two RCA Y-cables and two pair-of-RCA to TRS cables, but now you have a fairly long string.

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  • \$\begingroup\$ Schematically, yes! That's exactly what I meant. I'm hoping to discover a reasonably simple way of accomplishing the desired result using an off-the-shelf adapter or two. \$\endgroup\$ – jdmc May 10 '18 at 22:35
  • \$\begingroup\$ @jdmc Ah — I had understood your question as being how to make an adapter instead of stringing together multiple adapters, not that you wanted a minimal set of adapters. I've added a suggestion. \$\endgroup\$ – Kevin Reid May 10 '18 at 23:17
  • \$\begingroup\$ D_K has lots of dual jacks and single wired plugs. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 11 '18 at 6:33
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There is no magic involved in separating the Left and Right signals from a 3.5 mm (1/8") plug. The plug has three connections: Left from the tip of the plug, Right from the ring, and Ground (common to Left and Right) on the sleeve.

Ready-made adapator cables should be readily available to go from a 3.5mm stereo plug to two, 1/4" TS plugs, or to two RCA plugs (and probably other combinations.)

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