Continuous hum cancelling on the input using DSP

  • I recently purchased an Electro Harmonics Hum Debugger pedal to try to get rid of a really annoying hum that I have been getting from my single coil pickups. This pedal is not a noise gate, it uses a DSP to identify the hum in the guitar output signal and then continuously filter it out. Remarkably it works really well, with only a very small effect on the guitar tone that I can completely remove (to my ears anyway) by increasing the middle and presence a little. It is a really useful alternative to a noise gate which has no effect on the hum when the gate is open.

    I’m not sure how the pedal identifies the hum in the signal, but I would think the Kemper team would find this quite easy to do. It could work as a pedal in slot 1, or an on/off option on the input. The Hum Debugger pedal only has an on/off switch and must be continuously analysing the signal to identify the changing hum as the guitarist moves around. The Kemper could go one step further in a recording environment where the guitarist can keep still, by having a calibration function which allows it to first analyse the hum on its own without any notes being played. This would maybe further minimise the residual hum and also the effect of the hum cancelling on the guitar tone.

  • Thank you, Christoph.

    Isn't that great, djdyer? You may just have to crank the knob up a tad from where it is now.

    Considering the fact that this "noise-print" DSP is always on (other than for a setting of "0", I assume), it's yet another reason why the KPA is so great, and all the more reason why the throughput latency figure never ceases to amaze me.

    PS: Christoph, I'd like to buy a poster of you for my studio wall - I've even told people that you're my hero. Where can I buy one and how much is it? On second thoughts, it doesn't matter how much it is! LOL

    Seriously 'though, not a day goes by where I don't thank my lucky stars that you've done what you've done. Thank you!!

  • I recently purchased an Electro Harmonics Hum Debugger pedal to try to get rid of a really annoying hum that I have been getting from my single coil pickups.

    Hello djdyer,

    Assuming you are not an ultra-purist...have you ever considered trying noise-cancelling, stacked humbucker type Strat pickups? I am not talking about the side-by-side humbuckers that fit in a single-coil slot (e.g. Hot Rails). Rather, the stacked design that looks exactly like a traditional single-coil. I find the stacked design has a much more authentic single-coil "Strat" tone, due to the similar magnetic field geometry. I personally prefer the relatively low output Dimarzio HS-3s / HS-4s. The Dimarzio Virtual Vintage series is also great. Seymour Duncan has their own models, as does Fender (Vintage Noiseless).

    I use to be a vintage single-coil traditionalist. However, I eventually got fed up with the noise and hum issues. In particular, the unpredictability of single-coil noise/hum when playing in different venues. While I don't play out much anymore, I now find I can't go back to the buzzy world of true single-coils.


  • Thanks for all the responses. I had assumed the noise gate knob was just a simple noise gate. I should have known better! I just tried it on full and yes it is working to reduce hum all the time. Quite a nice effect on the tone actually. Like an auto swell.
    However, i could not find a setting that was as effective as the hum debugger. There is still a noticeable hum that appears as the note is decaying. The hum then disappears as the note ends just like a normal noise gate. The hum debugger cures this somehow.
    Can i suggest that when you press the input button one of the 4 buttons above the screen is labelled 'sample hum' and pressing and holding this button tells the kemper to analyse the hum it hears and then only correct for that sampled hum rather than to continuously listen to the signal and try to seperate the hum from the notes. That could improve the hum cancelling routine for home or recording situations where we can keep still and the hum would be constant. Only my assumption ofcourse that this would help.
    I've not tried changing to noise cancelling pickups. Too lazy!
    Ironically, now that I can remove the hum effectively with a simple tap of a pedal I find that the hum does not bother me anymore and I leave the pedal off most of the time. Seems it was not the hum that was annoying me but the inability to get rid of it!