No Input Mixing Tutorial

This video takes a look at ‘no-input mixing’ – the idea that you can use feedback loops within mixers to generate sound.

Most users try to avoid noise when mixing. No-input mixing is about embracing the noise inherent in mixers and using it to synthesize sound. 

No Input Mixing

How does this work?

Here’s an explanation via the Department of Performance Studies at Texas A&M:

Two facts allow an audio mixing console to become a synthesizer without any other inputs, when you put it in a feedback loop (meaning you feed its output to its own input):

1) Mixers contain amplifiers that make weak sound stronger, and

2) No audio hardware is perfectly silent; it is always introducing a (hopefully small) level of noise into your signal.

Put these two facts together in a feedback loop, and the mixer amplifies its own system noise, allowing it to bloom into its own full voice.

The mixer can then shape that voice with its rich filter (EQ) and signal-routing options. Volume and filter controls can gradually add or remove resistance to certain modes of resonance (acting a bit like a trombone slide) and signal routing switches can quickly redirect a signal through a path with different properties (somewhat like the valves of a trumpet).

If you want to try no-input mixing, they recommend using it with gear that you can live without, because you could potentially damage the mixer or your speakers with extreme signal levels.

The video demo is via The Tuesday Night Machines. Gear used:

  • Behringer Eurorack UB1202 Mixer
  • Thomann t.mix 802 Mixer (discontinued)
  • Zoom R16 (recording)

Have you tried no-input mixing? If so, leave a comment and let us know what you’ve tried!

17 thoughts on “No Input Mixing Tutorial

  1. I’ve performed using no inputs, in a slightly different fashion. I used an ARTcessories “CoolSwitch” A/B Y switch to make an effects loop consisting of old Boss digital delay and pitch shifter pedals, and an Electro Harmonix “Frequency Analyzer” ring mod pedal… the A channel of the switch made the loop (outputs to inputs) and the “Y” channel went out to a practice amp. Then I got a mic from the sound guy at the venue, and he ran the output of the practice amp to the house sound. You can get really intense, crazily-effected feedback this way, but by modifying the effects’ depth and time settings, you have a lot of control too.

  2. try also a passive (3×3 or 4×4) matrix mixer…they´re affordable and easy to build..very fun too when hooked to old delay-reverb pedals 😉

  3. When I was trying to circuit bend my distortion pedal, I came up with the same effect. I think I made feedback loop 🙂 I have inserted pot and tried to change character of feedback loop and it sounded really interesting.

  4. I used to do this in the mid 90’s with an old Realistic mixer that had a graphic EQ and a Fostex 4 track, try putting a drum machine through the mixer too at the same time 😉

  5. Reading the comments here, every comment voted down except the one that says, you can get an app do do that – this is what we have become – I am now going to walk into a field and shoot myself in the face.

  6. I have been experimenting with no input mixers for awhile now. I am starting to think that the feedback is caused by the frequency resonance of the transformer in the machine rather than noise in the circuitry (op amps, pots, caps and the like) Not sure if anyone else has toyed with this idea. I am no electrician but i dabble a bit in mixer guts and circuit bending stuff

    I know it is possible to make a NIM with just a transformer, a battery powered amp (headphone amp or the like) and a potentiometer and some clip leads.
    Most mixers are built to have very little noise in them, so the transformer thing seems right


  7. Maybe I’m reading it all wrong, but it sure seems to me that David Willis was basically doing this with The Booper way back in the mid 70s.

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