I have purchased a 3.5mm port online. I want to wire them to a mono output to a amplifier board. I have worked the ground and right and left channel terminals on the port. I am not sure how you would wire this as a mono output. Would you solder both the left and right terminals together or just use one terminal either the left or the right? If not would I need some sort of adapter? Thanks Very Much!

  • \$\begingroup\$ Your description is slightly unclear. Do you have a mono 3.5mm jack going into a stereo plug? \$\endgroup\$ – alphasierra Dec 25 '15 at 23:30
  • \$\begingroup\$ No, I just have a stereo 3.5mm plug going to a mono amplifier. The input may be stereo. However I just want to know how to achieve a mono output from a three terminal plug. \$\endgroup\$ – James Dec 25 '15 at 23:33
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    \$\begingroup\$ Please clarify: (1) you have a mono amplifier. (2) You want to wire a 3.5 mm jack socket for audio out. (3) You will plug in a mono 3.5 mm lead (or a stereo lead but not use one of the hot wires). \$\endgroup\$ – Transistor Dec 26 '15 at 1:30
  • \$\begingroup\$ Are you saying your amplifier has a 3.5mm jack socket wired as mono? So far this question is unclear. \$\endgroup\$ – Andy aka Dec 26 '15 at 1:33

The problem comes from what "type" of mono input you want. There are two

  1. TS, also called Tip-sleeve, is an unbalanced, single-ended signal. If your amp uses this input then you can just plug it in, and hear everything out of the Left channel.
  2. TRS, also called, Tip-Ring-Sleeve, is an often balanced (not required), differential signal. For this you would need a converter. Details about how to create one should be asked in a different question.

Do note: if you want mono, you'll only get the left channel's audio. This can be quite odd sometimes. There are ways of putting two channels into one channel. This is also the subject of another question that you can ask if that's what you want.


You can generally use a stereo cable going into a mono jack. If you take a look at This Picture for a product from Digikey you can see the mono audio signal contact will make contact with the second ring on a stereo jack. So it will only use the right channel.

I don't know if that's universal, but almost every one I've seen tends to do that.

  • \$\begingroup\$ So I shouldn't join left and right terminals just the right one. \$\endgroup\$ – James Dec 25 '15 at 23:40
  • \$\begingroup\$ You can, just put some series resistors in line with each channel. That should be fine for this application. Commonly I see values in the range of a couple hundred to low thousands of ohms. Depends on how much attenuation you want. That's not the sort of thing you'd want to do if you were combining a higher power stereo output because it could damage the amplifier. For low power going into an amplifier input it should be fine. \$\endgroup\$ – alphasierra Dec 25 '15 at 23:47
  • \$\begingroup\$ Mono will use the tip, not the ring. That way it will work with mono or the left channel of stereo systems. \$\endgroup\$ – Transistor Dec 26 '15 at 1:31

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