In this free video tutorial, Production Expert team member Julian Rodgers demonstrates a trick using a feedback loop within an analogue mixer to create an oscillator. If you've never tried this you really should as its enormous fun!
Notepad Mixer And Free Plug-Ins
In this example only a single feedback loop in created and some reverb and delay are added in Pro Tools, however, this technique becomes more and more interesting with additional complexity. For example, Julian can recall losing an entire afternoon to creating an amazing mixture of horrible noises in a gig venue using a 24 channel analogue Midas, a couple of Lexicon reverbs, some compressors and gates (external sidechain anyone?), some Yamaha SPX multi-effects processors and a limiter for safety!
With three people setting up multiple feedback loops and cross patching using aux sends the possibilities for building layers of sounds using looping delays and especially the rather grainy pitch shifting in the SPX units were extraordinary. Doing all of this through a large PA system helped too...
If you have an old mixer lying around see what trouble you can cause by abusing it using feedback loops!