1
\$\begingroup\$

I'm repairing my simple wired headset which is composed of two little speakers and one microphone. The audio and mic jacks are separate. The speakers work fine. But the microphone is very noisy. As I was playing with wires, I found out that when I touch both ends of the speaker wire, the microphone noise goes away. Short-circuiting the speaker wire alone won't work. I have to literally touch the wires. This is rather bizarre to me. Do you have any idea what should I do?

I have seen this happening in lamps flickering too. The moment I touch the metal body of the lamp holder, the flickering goes away :-/

\$\endgroup\$
2
  • \$\begingroup\$ Welcome to EE.SE! Can you describe the sound? Is is 50/60 Hz with overtones? \$\endgroup\$
    – winny
    Apr 15 '20 at 13:52
  • \$\begingroup\$ One possibility is that the wire is broken or almost broken and when you touch the wire it makes solid contact, but when you let go of the wire it makes intermittent contact. If that is the problem you can narrow it down by wiggling the wire deliberately in different places. Usually it is near a connector that the wire breaks. \$\endgroup\$
    – mkeith
    Apr 15 '20 at 20:48
1
\$\begingroup\$

The braid of the microphone cable may be disconnected at the plug.

The microphone cable braid, when properly grounded, shields the signal wires from electromagnetic interference/noise.

The ungrounded braid would itself pick up the interference/noise and couple it to the signal wires.

The cable connections are to be checked at both ends to confirm the cause.

\$\endgroup\$
2
  • \$\begingroup\$ Please add a reasoning to your one-line answer. Thank you. \$\endgroup\$
    – Ariser
    Apr 15 '20 at 15:14
  • \$\begingroup\$ Thank you, Pedram. \$\endgroup\$
    – vu2nan
    Jun 22 '20 at 10:43
1
\$\begingroup\$

This can be caused by ground loops or grounding problems in general. You are applying a new ground point with your fingers when you touch the wire. I dont know the exact noise nor do i know the "touch"-setup. But maybe this indication might help you solve the problem.

Edit: Clarification: A ground loop or a poorly grounded wire can be vulnarable to EMI an thus can caputure interferences from other devices or power cords. This could be what you hear

\$\endgroup\$
3
  • \$\begingroup\$ I tried using a multimeter to check for available shortcircuits but found none. However, I guess my computer is making the loop somehow, maybe it has a common ground right? That has made me suspicious because for getting a more clear sound from the microphone, is only possible when BOTH mic and headset are connected to the same computer. \$\endgroup\$
    – Pedram
    Apr 14 '20 at 14:50
  • \$\begingroup\$ @Pedram Ashofteh Ardakani, Which jacks were the headphone and the microphone plugged into when you noticed the problem? \$\endgroup\$
    – vu2nan
    Apr 14 '20 at 18:41
  • \$\begingroup\$ @vu2nan The two corresponding jacks on my laptop. I just plugged them into where they should've gone. The speaker works perfectly. The mic works too, but it's too noisy. So, they are connected to the right ports - if that's what you mean. \$\endgroup\$
    – Pedram
    Apr 15 '20 at 11:09

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.