When you get right down to it, there’s no formula or complex calculus for determining what makes one particular axe-slinger stand out from the crowd. Is it all in your technique, or is it all about that elusive feel? Do you have rock-star swagger, or are you the more cerebral type? Are you a badass riff machine, or can you solo circles around so-and-so?

Whatever the defining mojo really is, one thing we know for sure is that we know it when we hear it. There’s an unmistakable signature to a gritty Keith Richards riff or a kamikaze Jimi Hendrix solo. Strip it down to its basics, and most of what makes it memorable comes from the personal stamp of the guy doing the playing. But there’s something else afoot here. The magic isn’t just in what they’re playing or how they’re playing it—it’s in how all that interacts and intertwines with sonic signatures imparted by the gear they use.

Throughout the history of electric guitar, so much of that magical mojo has been spun from the electric innards of stompboxes—wah-wahs, phasers, flangers, envelope filters, fuzz units, and more. Effects pedals are the great democratizers: Get yourself a distortion box, and you too can be a rock star! But, more importantly, they’re portals to new worlds of tone. Anyone can use them, and anyone, with the right combination of devices, timing, and/or technique can get a sound out of them that no one has ever heard before. Whether that’s a sound worth hearing again is a matter of taste, but when everything clicks, it can be legendary.

That sound can happen instantly, almost by accident, or it can take years of exploration. As Omar Rodriguez-Lopez, guitarist for the Mars Volta, will tell you, curiosity does have its payoffs. “I remember when I got my first delay pedal,” he says. “I’ve always used pedals to hide my playing, and now as I’ve been able to evolve as a player, I can remember that the thing I loved most about the delay pedal was that I could use a certain time setting, and it sounded like I was playing way more than I was. It made me want to learn how to play the way the delay sounded. The pedal itself pushed me to learn more about my instrument. I always liked this idea and this part of the process. It’s about learning from your gear, and learning from these little metal boxes that supposedly have no life and no influence, you know?”

There are countless examples of inventive players who’ve redefined how we hear music and guitar because of the unique way they’ve absolutely owned a specific effect pedal. It would be impossible to try to list them all, but here we’ve chosen what we believe are the 10 most historically significant instances of intrepid players who pushed a specific stompbox to its limits and changed the world as we know it.