The BOSS FZ-5 aims to simulate (and then surpass) three vintage models of fuzz: 1) the Dallas-Arbiter Fuzz Face, 2) the Maestro FZ-1A, and 3) the Octavia Fuzz. BOSS uses Roland's COSM (Composite Object Sound Modeling) to digitally replicate these classic 60s and 70s sounds.

Fuzz Face sounds burly and bottom-heavy with a mild Lo-Fi feel. Maestro is even more Lo-Fi, and honestly if you weren't sure what to expect, you might swear the pedal was broken. The sound is just so thin and high - you better know what you're doing with this setting. Octavia is the clearest setting of the three and has that lovely Hendrix effect of producing the tone an octave up.

The "Boost" dial basically seems to function like a gain control, making the fuzz effect more prominent. Note that the 12 o'clock setting on this dial is equivalent to the maximum setting on the respective controls of the original pedals, and anything further is new territory (hence BOSS's attempt to "surpass" a strictly retro sound).