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

  • Hi,


    I received my profiler yesterday, I did a quick test with O.S version 7.1.4 installed by default with default profiles and everything seemed fine (from what I recall).

    I then took the time to update the OS to the latest public Beta and add a few profiles freshly downloaded. When I plugged my guitar I experienced a sort of feedback sound through my headphones. Since the OS did not seem really stable (Profiler froze several times) I thought it was due to the OS so I reverted back to the latest public (7.5) but same thing occurs.

    I continued the investigation and tried all those things :

    • Change Power strip
    • Use power socket directly and change power socket in the same room
    • Use power socket from an other room
    • Turn all the lights off
    • Apply Factory Reset on the Profiler
    • Try different Jacks
    • Try different guitars single coils and humbuckers
    • Try different headphones (Closed headphones only)
    • Play the guitar outside of the room with a long jack and headphone cable extension

    Nothing really worked, but here are my findings :

    • Headphones are closed so there is no way the signal goes from the headphone to the pickups
    • It occurs with clean and crunch sounds -> Of course the more gain, the more noise in addition to the feedback noise
    • Feedback stops when I mute the strings with my hand or turn the volume to zero on the guitar, however it doesn't really decrease when I turn down the volume
    • Strangely enough, it seems that Single coils introduces less feedback than humbuckers (I tested with my Telecaster, SG and LesPaul)
    • Feedback occurs when the jack is connected to the profiler but not to the guitar (without touching it)

    Good thing is that I managed to mostly ged rid of it with the input noise gate:

    • I have to set it to almost 7 for humbuckers with profile which have gain set to noon or more and 5 for clean profiles.
    • 6 to 6.5 for Single coils seem to work well for saturated profiles and 4 for clean.
    • Unfortunately it seems that it affects the tone (probably negligible but still) and sustain

    Is it normal ?

    Am I the only one experiencing this (I searched a bit but did not find real answers) ?

    Is my unit faulty ?

    Is it a problem with the headphone input (Unfortunately I don't have monitors yet and my unit is non powered, so I cannot test anything else)?

    Are there any setting I am missing ?

    Do you all use the noise gate input ? If yes to which extent (because the value i have to apply seem pretty high)?


    I can leave with the noise gate trick however since it is brand new and it's not cheap I would rather make it repair or exchange it while I can. Especially since I plan to use it a lot with headphones


    Thanks in advance !

  • I had the same problem.
    It occurred when the input section was locked.
    It includes the noise gate level which was then set to zero for all rigs (before that the level was saved in the rig)
    That also appeared at the same time, when i did an OS update to a beta version.
    not sure if the locking was done by the upgrade or by myself :/

  • Cool, how did you fix it ?

    How do you unlock the input section ?

    How can you tell that the input section is locked (visually I mean on the profiler itself) ?

    It may be due to a bad manipulation on my side, I need to read the instruction manual ...

  • Cool, how did you fix it ?

    How do you unlock the input section ?

    How can you tell that the input section is locked (visually I mean on the profiler itself) ?

    It may be due to a bad manipulation on my side, I need to read the instruction manual ...

    the locked status is indicated by a lock symbol on the right side of the display. To lock or unlock a section you need to press the lock button while you are in the section you want to lock or unlock. But from your description I really doubt that this is the reason for your issue.

  • Thanks for your answer, I received a lot of thing to try from the support as well (try different inputs and outputs to find out what can be the root cause), I will try them all and will let you know the outcome.

    I'll also check if the input section is not locked, just in case and let you know.

  • Thanks for your answer, I received a lot of thing to try from the support as well (try different inputs and outputs to find out what can be the root cause), I will try them all and will let you know the outcome.

    I'll also check if the input section is not locked, just in case and let you know.

    If you press and hold the lock button, anything that's currently locked will be lit. Pressing a lit button should turn the LED off, meaning that block/section is now unlocked.

    “Without music, life would be a mistake.” - Friedrich Nietzsche

  • Hello,


    As discussed I come back with my findings.
    First interesting thing, when I came back from work and turned on the Kemper, The problem was gone. I played for 10/15 min and decided to have dinner. When I came back the problem was back.

    So i tried different inputs and outputs it did not change anything and the problem persisted, I also reset the unit (RIG button + System button pushed while turning on the unit) but it didn't help either and the input section was not locked.


    Here is a video of the problem :
    https://photos.app.goo.gl/qY43U2R1jUE5nNwJ9


    The sound is coming from my keyboard amp, I reproduce the problem with all my electric guitars.


    The good news is, the profiler is not faulty, because I can reproduce the issue by plugin my guitars to the keyboard amp directly
    .


    If I plug my electro Yuk or my acoustic guitar to the profiler the problem disappears


    So I think the problem is related to pickups ? Due to interference ? Or electric problem (It is not a ground issue since everything is grounded properly -> I double checked yesterday)?


    Do this ring a bell, do you have any idea what I can try ?


    I tried turning off almost everything in the house or unplug it, but I guess if it was purely electrical I should be able to reproduce the issue with any guitar plugged in correct ?

  • playmo77

    Changed the title of the thread from “High pitch feedback sound with headphones” to “High pitch feedback/squeal”.
  • Is there an audio interface in the equation?

    Sounds like ground loop problem with interface connected to pc I've had before.


    * Back of profiler, there are series of red buttons which are ground lifts- if you haven't already- try pushing those, see if anything changes.


    * if you have more than one device connected to your audio interface (inputs and outputs - anywhere), disconnect them until noise stops. Troubleshoot from there.


    *You could always test your house wiring, but pretty unlikely that's the cause. You can get a tester at a hardware store for cheap. Really doubt that's your problem, though.

  • Yes I think it is q ground loop problem.

    It appears only with my electric guitars, It disappear when I touch something metallic on the guitar (bridge, strings, pickups ...)

    I have the same problem with all my amps in the house not just the kemper

    And the problem is not present when the guitar is unplugged or volume is zero


    I'll order one of these and see how it goes ...

    I'll let you know but I think I have isolated the problem.

  • playmo77

    Changed the title of the thread from “High pitch feedback/squeal” to “High pitch feedback/squeal -> Ground loop problem ?”.
  • Hello,


    I finally received the hum eliminator, it does not fix my issue and it is actually even worst with it.

    My problem does not always appear and I think I found the source of the problem : My neighbour's Air Conditioner !

    When it's off no problem, when it is on however I hear the squeal.

    Anyone had a similar issue ? If so did you manage to fix it ?

  • playmo77

    Changed the title of the thread from “High pitch feedback/squeal -> Ground loop problem ?” to “High pitch feedback/squeal -> Coming from neighbour's air conditioner”.
  • It appears only with my electric guitars, It disappear when I touch something metallic on the guitar (bridge, strings, pickups ...)

    I have the same problem with all my amps in the house not just the kemper

    And the problem is not present when the guitar is unplugged or volume is zero...

    I've been there, done that. I had a dirty power noise.

    In my case a bit of KPA global noise gate (0.1) and a Furman power conditioner with AC filtering did get the job done. (Furman PL-PLUS C)


    By your description, it doesn't look like a grounding issue. Disconnect all connections from the KPA, use just your guitar+KPA+headphones, do you still hear the noise?

    If your acoustic is ok, then there might be an EMI picked by your pickups or dirty power issue.

    Make sure you are away from your cellphone and the airCC unit, move around and see how it goes, try wireless and/or high quality twisted shielded cables.


    Check the following links, if you need more ideas...

    1. Dirty power: https://www.proaudioland.com/n…ne-noise-and-dirty-power/

    2. EMI: https://www.proaudioland.com/n…ro-magnetic-interference/

    3. How do you get rid of electrical noise on stage? SOLVED

  • Thanks Syntek !


    I read all your links, it was very interesting.

    After reading a lot of stuff I think you are right it is down to either EMI or dirty power noise.

    Since we live in the same building my neighbour and I, I suspect power pollution through the ground (since we share it)


    To answer your questions, all the tests have done were with only KPA + Guitar +Headphones. The sound that you hear in the video I posted above comes from KPA through a little keyboard amp with just my guitar plugged in. So yes I hear the noise always when the AC is on. In order to mostly get rid of it I need to push the Noise gate to 6/7, which degrade the tone IMHO.

    My cables are not the problems I think I use those :

    https://fr.audiofanzine.com/ca…dio/proco-sound/Defender/

    and I also tried with other cables, cheaper but descent.


    I tried to move in my room and in the corridor while plugged-in to the KPA and headphone but the sound doesn't seem to change.


    So next will be either to try a Furman (M-10x E for starters ? since I do't think I need the fancy features of the PL-PLUS-C) or a UPS, I don't know which solution is better and if an offline ups could help or if I need to go for a line interactive or online


    Or go wireless, I don't like this idea (I am probably too old school, took me some time already to decide to buy the KPA ...), but it may solve the problem ... so i might try it

  • Another test you can do is just Kemper+headphones+cable (ground the cable with your hand), do you hear the same noise?


    The M-10xE has AC line filtering (RF/EMI), it should help if the issue is related to that.

  • I did the test as well, yes I have the noise with just the cable in my hand, it is actually louder when i touch it but I guess it is expected.


    Hopefully the Furman will help, AC filtering (RF/EMI) is what I was looking for as well in UPS.


    One thing I will try is to use q ground lift of some sort (only for test) , my assumptions are :

    - if I don't have the problem, when the ground is not plugged, it means that the ground is polluted by the Air Conditionner -> Furman may fix it

    - if not, problem is in the air, maybe going wireless would help ?


    One thing I don't understand is that when I plugged the Hum Eliminator it actually increased the noise, I was expecting this to work or not work at all but not increasing the issue, any idea ?

  • Disconnect the keyboard amp for any testing. Just use your headphones to keep it simple.


    I believe Kemper ground lifts will not work in this case, since you don’t have anything connected to the KP outputs for testing purposes.


    The cable test should not be louder, make sure you touch just the plug of the cable not the top tip. If you disconnect the cable completely do you still hear the noise through you headphones?