Essentially the 'Voice' control takes you smoothly from a Fender 57 Deluxe sound at far-left, through a Bassman/JTM45 sound in the middle, to a Mesa Boogie/JCM800 sound at far-right. The genius of this pedal is in its 'Voice' control.
The 'Gain' control sets the amount of grit and the 'Level' control sets the ultimate volume of the pedal's output. The simplicity of its design is this - the top of the pedal contains three bands of very useful and powerful EQ - bass, mid and treble. Z head paired with Celestion V30s for grind, and a Soldano with Greenbacks for high-gain - only to find that when I was actually at the gig, that I hadn't programmed in quite enough grit on this patch, or slightly too much reverb on that - and found myself squinting at a little LCD screen trying to edit patches while the audience lost interest in me. Having used a Pod HD500 for years, I was used to spending hours at home programming presets, geeking out over using a Fender Twin model for clean sounds, and a Dr. However, though I bought it as a compromise, I soon came to love its hands-on, menuless simplicity and interactive tube-like response. I needed something that could take me from glassy clean to bluesy grit, with only the occasional venture into high-gain territory. but not have to lug around my Pod HD500 for a simple corner-of-a-bar gig.
I bought this pedal as I needed to be able to simulate the sound of an amp so that I could play direct to P.A. As such it is designed to simulate a range of American amplifier sounds, from a Fender Deluxe to a Mesa Boogie. The Joyo American Sound is another of those naughty Chinese pedals that 'borrows' its design from a certain New York City-based designer of analogue amp simulation pedals. A versatile amp sim solution that does everything you need without going digital.