MXR M - 103 Blue Box is a quite interesting pedal. Unfortunately I haven't really found any use for it. It's a really easy to use pedal with only two knobs. Unfortunately the features aren't that great. There is just a blend knob and a volume knob, which means there is just one knob to control the octave effect and the fuzz/distortion effect. The sound is pretty good, but you can't get a clean or a cleaner sound together with the octave effect. Whenever you use the octave effect the sound is very distorted and it's quite hard to actually separate different notes, because of the heavy distortion and fuzz, additionally you can't hear any chords unless you turn the blend knob up, which means you don't actually use the octave effect. So if you turn the blend knob up then you won't hear any of the octave effect and if you turn it down then you only get a very weird, dirty and muddy octave sound. If you turn the blend knob to the middle you will get a mixture of the fuzz/distortion and octave effect but it's still very dirty and muddy. It works quite well though as a dirty fuzz pedal when you have the blend turned up. Unfortunately this pedal didn't meet my expectations.
Ok, Jimmy Page used it once, but it's got much more going for it than that. Leave the Output knob up ay full - it's useless anywhere else. With the Blend knob at full, it's a gnarly fuzz. With it rolled back, it's a fuzzy minus 2 octave glitch monster. And I mean that in a good way! So pick your spot between the two, and go mad. You'll need to experiment with which pickup and guitar tome setting to use to get the most out of the -2 octave. If you're even just a bit handy with a soldering iron, I'd recommend putting a sqitch on the C11 capacitor, which brightens the sound up a bit. Also, a switch to flip between -1 and -2 octaves is a good and easy mod to do. i've done both (first modded pedal I've done), and it improves the pedal 100%. There's a bit of bleed-through on the dry signal. At the moment I'm just yanking out the power cable to remedy it, but I might buy/build a bypass looper to solve it. Modding it for true bypass might me a little more than I can handle. It benefits from an overdrive in front of it. Or be The Melvins, and just use it and a Rat (or Moorer Black Secret) and fuzz out!