Microphonic pickups and squealing with profiler

  • Hi all!


    I have a squealing issue since I have purchased my profiler, and I use plexi and jcm800 profiles, not high gain profiles.

    This week, I have solved this issue by lowering the pickups of my gibson R8, mounted with custombuckers.

    But this squealing issue is still on when I get closer to my cab in order to have a natural feedback.


    It's the first time I have this issue with those pickups, and when I use my 50w silver jubilee clone, I haven't problem like this, even at loud volume...


    It's very problematic for me to not create natural feedback...

    Any advices?


    Thx

  • had a similar experience with higher gain sounds (a few years back) when standing too close to the speaker cab. In my case it was actually the PA cab. Turning myself/guitar 45-90 degrees to the cab avoided the problem. I’ve noticed HK powered cabs are bad at spilling their magnetic field. Some kind of lpf may rid the squealing. I ended fitting noiseless pickups to totally avoid they problem at the cost of a slight change in tone. I guess in a traditional guitar +amp+mic setup up there is a natural lpf as a result of the cab and mic. Cheap pickups can also be microphonic and cause problems too.

  • If you are using the same guitar and cab with both amps (and are standing in the same spot relative to the cab and the cabinet is in the same spot in the room) then the cause must be in the KPA.


    The KPA doesn’t cause microphonic feedback if the profile is the same as the reference amp. Therefore, there must be something in the settings or the actual rig (such as more gain or different EQ etc). My guess would be that the profiled rig has more gain.


    Start by making sure all FX are turned off and check the Input menu settings in the KPA. Is distortion sense set high which would have the effect of a global gain boost?


    If everything is OK there, move through the signal chain. Look at Amp and Cab settings in case something is strange there but it seems unlikely this would be the cause.


    If the feedback isn’t present with just the Stack block enabled, start adding back FX one at a time until you find the culprit.

  • Here’s my theory. There will be some here that disagree and i may be wrong.

    As i understand, a traditional guitar +amp +mic setup has a couple of natural lpf as part of the signal chain. The speaker and the mic being the main LP filters. “Profiling” this arrangement, as we do, captures “that sound” which is assumed/deduced by the kpa from the speaker/amp frequency response (besides all the other characteristics and tube magic along the way) and the kpa creates a “profile” of that sound. I think we all know that but not 100% sure what the secret recipe actually is!

    I believe the kpa still allows some high frequency components to pass from the input through to the output stage through this “profile” which is a “special” algorithm rather than a traditional LPF in the sense of that which was part of the original signal chain, hence the HF (and squealing) makes its way to the output.

    Using a kemper it is likely we are in closer proximity to FRFR speaker systems which is what is reproducing the kpa sound, that’s usually our monitor or maybe the PA. Perhaps applying a LPF (10khz upwards??) at the output stage of the kpa (as it goes into the desk) may offer some taming of the HF annoyances which, ironically, are minimal if something like an SM57 was the source feeding into the desk.

    I could be completely wrong here but this is my theory based on my experience. Certainly, moving off axis or swapping for noiseless pickups solved it for me when going through certain PA systems, something i don’t recall experiencing in pre-kpa days with a traditional rig of a 4x12 cab and SM57 into the desk.

  • slateboy I have no idea whether your theory is correct or not. What goes on inside the Kemper is a mystery to me. It might be musical elfs singing for all I know 🤣. However, in this case the Op is getting the feedback when using a regular 212 with V30s so it can’t be an issue caused by using FRFR speakers while being closer and on axis than a traditional rig. In this case there must be something else going on.

  • I suspect this set up is just highlighting an issue that is already there. I do not believe there is something inherent in the KPa making it more prone to feedback - I have found the opposite.


    I would do what you are doing and start ruling out the guitar...

  • Yes. But the question why this squealing not present with my tube amp?

    Even at loud volume, I have feedback, it's normal, but not squealing

    No idea and all we can do is speculate.


    As previously said the KPA/profile is probably picking up a frequency that isn't at the forefront with your tube amp. Any changes to the signal chain could cause it.


    So, best course of action is to start ruling things out. This is NOT normal.

  • Which stomps do you use in the Kemper? They might cause unwanted squealing when they're not set properly. For instance a compressor+drive+distortion+eq in front of the Stack might go bananas.

    Check the settings of the stomps.