High pitch feedback/squeal -> Coming from neighbour's air conditioner

  • This sounds like magnetic noise/interference (EMI) to me. Humbuckers may work better than single-coils, but I've been to places where it has been impossible to use any electric guitar due to squeal on one or more frequencies in the 1-2kHz range. Most acoustics use piezo to sense vibration or a membrane-based microphone and is thus not affected. A power-conditioner will not help in this situation. EMI-sources require specialised equipment to locate, but turning nearby gear off/on is a start. OP mentions that it seems to come from an AC-unit. That makes sense. Anything with an engine (fans etc) along with electric heaters and other gear that use a lot of power are the most likely culprits. Equipment that are potential EMI-sources should be designed with a grounded shield to keep the noise in so in this case the neighbor with the AC should check to make sure the AC is properly grounded.

  • If you haven't already swapped it, this sounds like a cable issue to me.

    Tried it already, all the cable sound the same, and not problem when the AC is off.



    This sounds like magnetic noise/interference (EMI) to me. Humbuckers may work better than single-coils, but I've been to places where it has been impossible to use any electric guitar due to squeal on one or more frequencies in the 1-2kHz range. Most acoustics use piezo to sense vibration or a membrane-based microphone and is thus not affected. A power-conditioner will not help in this situation. EMI-sources require specialised equipment to locate, but turning nearby gear off/on is a start. OP mentions that it seems to come from an AC-unit. That makes sense. Anything with an engine (fans etc) along with electric heaters and other gear that use a lot of power are the most likely culprits. Equipment that are potential EMI-sources should be designed with a grounded shield to keep the noise in so in this case the neighbor with the AC should check to make sure the AC is properly grounded.

    Thanks, I'll talk to my neighbor to check the issue with him and in the mean time I'll check with a ground lift or something similar to check if it comes from power or from the air.

    What if the AC is not properly grounded ? What can I do on my end ?


    I'll let you know, thanks for the support.

  • I checked with my neighbor, it is the AC, the squeal is actually changing based on the how fast the engine is working.

    He will have a check with a professional to check both the unit and the way it is connected. Hopefully it will fix the issue. Worst case scenario we may be able to build a faraday cage around the unit if it is the problem.


    Wait and see, in the mean time I will try to plug my KPA with a ground lift or something similar to see if without the ground I can still hear the squeal.

  • Tried plug-in the kpa using a ground lift today. Same noise with and without the ground lift...


    it is then most likely coming from Emi or something similar ...


    Hopefully we can fix it on the ac unit ... otherwise I am screwed...

  • Yep I ll send back the kpa and go full acoustic

    It is not the KPA that is the problem. It works fine with all kinds of acoustic string-instruments too :)


    A magnetic-field strong enough to interfere with the magnetic pickups on a guitar may also be a potential long-term health-hazard for both you and your neighbour so you should really find a solution. I.e make sure the AC is grounded, or fix the AC-unit if it is broken.

    Edited 2 times, last by heldal ().

  • Sure, I was joking, one of the reason I bought the kpa is to be able to record electric and acoustic guitars as well as bass


    That being said, of course I plan to fix it. One way or the other. I actually retry the ground lift this morning and it does help reducing the noise. I will probably have an electrician check my installation and in any case I will most likely isolate completely my installation from my neighbor’s