

Which one of these do I need an adapter for? Can I plug a stereo cable into a mono jack? Obviously it doesn't make sense to plug a mono cable into a stereo jack, but what happens if I do?

S = Stereo; M = Mono;

Could someone fill in the ?

  CABLES:       M  | S
A           S|  ?  | X
C            ----------
K           M|  X  | ?


The mono jack has a tip and a sleeve, and where that sleeve is overlaps the stereo jack's ring and sleeve, so plugging a stereo jack into a mono plug effectively shorts your right channel to ground at the source, giving you a left channel only. Similarly plugging a mono jack into a stereo socket will allow you to hear your left channel only as your right channel in the amp will be grounded.


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  • So if you have a stereo jack on a computer, a mono jack on the mixer, does an adapter merge the two waves? or does it just ignore the right channel and connect the left? Oct 27 '12 at 19:13
  • And, in the case I want to connect a stereo-headphone jack on my computer -- to a mono-jack on my mixer, how do I do it? Oct 27 '12 at 19:15
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    @TonyS if you short tip and ring of a stereo jack together, and route that to the tip of a mono connector, you get a “poor man's mixdown” to unbalanced-mono. Not recommended, but should usually work, though impedance differences may cause the mix to be skewed (unlike in a balanced connection, a stereo connection is technically not required to have matched impedance) And if the impedance is too low (headphone connections), the stereo difference is dissipated as a lot of current which may damage the output. Aug 7 '20 at 14:53
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    If you short tip and ring of a balanced connection together, well, you basically just short both signal phases against each other and thus get no signal at all or a very feeble signal. Aug 7 '20 at 14:53

Please note, iPhone has a handy feature to convert stereo to mono output - no need to buy more connectors if this solution will work for your application :-) - thanks everyone.



I have also had this problem. No adaptor plugs seem to exist for 3.5 mm stereo plug to 6.3mm mono socket. So, I used a 3.5mm stereo plug to 2x RCA plugs with a short cable.

Then a plug that is 2x RCA sockets to 1x RCA socket - true stereo to mono "joiner". Then I used an RCA male to 6.3mm female plug . It's a hassle but that then allows a standard instrument jack to jack lead to head off to the line in input on the amp and not lose either of the left or right channels coming from your laptop or phone's 3.5 mm stereo output.

  • I also did this to get around the problem. I don't know why this was downvoted (ohwell, I probably do know, it's a very ugly hack). But I upvoted you again because this actually works and is easy to do without making your own cables. Oct 10 '20 at 20:20
