The Octave Multiplexer and the Octavix are both ANALOGUE octave effects. Analogue octave effects are “glitchy” and have “sweet spots” on the fretboard that you need to find.
Because of the way analogue octave circuits work, you can get a clean, BUT GLITCHY, octave DOWN. You can only get a “dirty” octave up. There are no glitch-free octave down analogue circuits, and there are no clean octave up circuits.
The Octave Multiplexer (octave down), and Octavix (octave up) are really about as good as it gets in the analogue domain. There is actually a digital octave down circuit that emulated an analogue octave down circuit by adding glitchiness.
Also, analogue octave circuits are NOT polyponic, especially the octave down. They can get really messy sounding.
If you want a clean, glitch-free, octave down or up you need to go digital which means either a HOG or POG. If you want to be able to play chords to emulate a 12 string or an organ, you need to go digital – HOG or POG.
