I have a 3.5mm jack mono output. I'm plugging standard stereo headphones into this jack, and it plays only on one side. I want the sound to come out on both sides in the headphones (same signal, but in both ears).

How can I cut and wire so that the mono signal goes into both speakers ?

I know there are some adapters on Internet that should do the job, but it's not an option anymore since I have to only 1½ day to finish this…

  • 2
    \$\begingroup\$ solder the mono signal wire to both of the stereo (left and right) wires and bob's your uncle. \$\endgroup\$
    – Gomunkul
    Commented Jun 18, 2016 at 19:55

1 Answer 1



simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Thanks for your answer. It looks rather simple. Does it mean I can just cut the cable of the headphones and fuse together the wires corresponding to the tip and the ring ? \$\endgroup\$
    – sylbru
    Commented Jun 18, 2016 at 13:07
  • \$\begingroup\$ Yes, and you would leave the old wire that goes to Ring unconnected (assuming there is a wire there at all) \$\endgroup\$
    – Daniel
    Commented Jun 18, 2016 at 14:11
  • \$\begingroup\$ Yes suggested mod sure will work but there is something you need to know about plugging in the mono plug into the stereo jack. The longer sleeve of the mono plug will short circuit the ring contact point of one of the audio channel to the ground. Some equipment such as portable audio players won't be happy with this. You may end up blowing their headphone power amplifier. \$\endgroup\$ Commented Jun 18, 2016 at 15:04
  • \$\begingroup\$ @soosaisteven Thank you for the warning. The case is a little bit different here though: I want to plug a stereo plug into a mono jack (not a mono plug into a stereo jack). Is there still a problem in this case? \$\endgroup\$
    – sylbru
    Commented Jun 18, 2016 at 15:52
  • \$\begingroup\$ In response to @soosaisteven's concern, use of a stereo plug at both ends solves that problem. The lead should be labelled "mono" and "stereo" at each connector. Schematic modified to suit. \$\endgroup\$
    – Transistor
    Commented Jun 18, 2016 at 17:52

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