I am trying to add electric guitar amplifier to my setup, and I am experiencing a lot of noise between the amplifier and a mixer.

My setup is wired as following:

  • Computer running Ableton
  • Zoom H4n running in audio interface mode connected through USB to the computer
  • 1010 Music Bluebox audio mixer plugged into Zoom H4n
  • Fender Mustang LT50 Line out plugged into one of the bluebox inputs

I have other equipment (Moog Studio 3, Waldorf Blofeld and 1010 Music Blackbox sampler) plugged into the mixer and it makes no noticeable noise. I have the amplifier and mixer plugged to separate outlets, I tried replacing power cables to both devices and used few different cables between the amp and a mixer but the noise is there as soon as amplifier is powered up. If I plug the amplifier straight into the ZOOM H4n noise is down to usable levels.

From the research I made I think there are two likely causes: dirty power or the amplifiers unbalanced line out. I think that the unbalance line out is more likely of the two, I'd expect dirty power to affect other equipment too if it was the problem.

I hope to avoid buying equipment that I ultimately don't need, hence the question: is direct input box what I need to remedy the noise. Should it be active, or can I get away with a passive one? Are there any other solutions? I've been thinking about getting a proper audio interface too. Could I get away with plugging the amplifier straight to the interface?

  • 1
    It looks like the LT50 Line Out is labelled 'TRS Balanced'. However, the Bluebox doesn't seem to handle balanced inputs, so using a TRS cable is not the answer. See 1010music forum
    – Zaq
    Jan 27 at 6:03

1 Answer 1


You have a balanced TRS output on the amp and a stereo unbalanced output on the mixer/recorder. If you want to test whether a DI would help, just use a TRS cable, record a stereo track, then subtract left and right tracks in postprocessing in order to get a mono signal.

If this difference track is reasonably good, a DI box (which does the "subtraction" in an analog manner) should work well.

  • DI box sometimes has ground lift, and if the source of the noise is a ground loop, this may help more than just the subtraction you describe. Jan 27 at 15:05

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