Bluetooth headphones, possible grounding issue with static mic noise?

I’ve been trying to fix an old Bluetooth headset which had its microphone cables cut.

My ultimate goal is to install the headset in my motorcycle helmet to use for calls and music.

I purchased a new mic and soldered the wires onto the headset microphone input. It consists of two wires (Positive and ground).

It works fine, except there is quite a fair bit of static background noise that completely disappears when I physically touch the ground wire.

I suspect this is a grounding issue? I initially thought it was a bad solder (I am not the best at soldering, and its a very tiny wire)… but I have since re-done the solder with a better connection and hasn’t changed the issue.

Anyone have any thoughts on how I can correct this?

Should also mention that my attempts at insulating the wires with shrink wraps and electrical tape also has no effect.

This could be a shielding issue as well - microphones generate very low voltage signals so they are particularly sensitive to interference. I suggest you try running the wires in twisted pair and shielding the cable.

Have a read of these Wikipedia articles for some more background info:

If you’ve still got issues after running shielded, twisted pair between the microphone and the ADC you’ve definitely got some probing to do!

Thanks Oliver you legend!

I twisted the wires together and then wrapped them in foil paper as a test… and the static has very drastically reduced!

I suspect that if I shield them properly using some copper tape (or could you suggest a good alternative?) and some shrink wrap, I may be able to eliminate the static completely.

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Awesome! Glad it worked!

Tbh Al foil works fine - just wrap it with electrical tape over the top. Or Al foil tape. Or if you want a neater setup you can buy cable shielding (or just use coaxial cable).

After a few attempts with foil I eventually gave up, I wasn’t able to eliminate the noise… it would only reduce it to a certain extent.

So I ended up grabbing some pre-shielded 2 core wire from Jaycar. The wire seems to be made for microphones and audio equipment.

This wire has completely solved the issue, it’s quite and crystal clear now.

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Glad to hear you got it sorted :+1: