Radiohead – OK Computer OKNOTOK 1997 2017

Jonny used this on the guitar solo in Paranoid Android in the studio. The Mutator is a stereo analogue filter and envelope follower with full control facilities. It contains two independent voltage controlled filters similar to those found in analogue synthesizers, which can be used to treat any external sound source. Each filter can be controlled from its own associated low frequency oscillator (LFO) and/or its own envelope follower section, which extracts the envelope contour of an input signal and applies it to control the cut-off frequency of the filter.

Each envelope follower can be switched to track either the envelope of the sound that is being treated by the filter, or that of an independent external control signal. This external control signal can be any audio source , eg. a drum sound, a guitar, a synth, a sampler output, or even a microphone. Thus the envelope characteristics of one sound can be superimposed onto the filtering contour of another.

Another switch on the envelope follower selects envelope follow mode or gate mode - in which the circuit detects whether a signal is above a certain threshold level before switching on.

In gate mode, the device can operate much like a dedicated noise gate unit, with the added capabilities of the analogue filter

The LFO's have four different sweep waveforms each and may be switched via a stereo link to produce stereo panning effects.