Augmented seventh Augmented seventh In classical music from Western culture, an augmented seventh is an interval produced by widening a major seventh by a chromatic semitone. For instance, the interval from C to B is a major seventh, eleven semitones wide, and both the intervals from C to B, and from C to B are augmented sevenths, spanning twelve semitones. Being augmented, it is classified as a dissonant interval. However, it is enharmonically equivalent to the perfect octave. Since an octave can be described as a major seventh augmented by a diatonic semitone, the augmented seventh is the sum of an octave,
Octave effect performances. Hendrix used an octave-fuzz pedal known as the octavia. Analog octave effects differ from harmonizers and pitch shifters which digitally sample the sound and process it to change its pitch. Octave-up effects usually use full wave rectification using diodes to "fold up" the negative part of the waveform to make a new waveform an octave higher in pitch. Octave-down effects are typically produced by converting the signal to a square wave, and then using flip-flop circuits to divide the frequency by two. This creates a buzzy synthesizer like tone. The MXR Blue Box used this method to create a