Here’s a set of simple, no-soldering-required mods that turn the stock Metal Zone into a pretty good-sounding hard-clipping dirt box with a great EQ section. They’re perfect if pedal circuitry and soldering looks like triangles and helicopters to your brain (like Allie Brosh’s Simple Dog, who I love); all you need to do is take some parts out with your diagonal pliers.
Unscrew the bottom plate of your Metal Zone; you should be able to work the circuit board down without removing the knobs or unscrewing the input and output jacks. You may need to push gently on the power jack to ease it back from its hole in the enclosure to get access to the component side of the circuit board.
Removing the hard-wired gyrator EQs
C35 – Remove it with cutting pliers
C25 or C24 – Remove one of these capacitors with cutting pliers
Choosing C25 results in a sound I’d describe as “aggressive,” having “bite” and “clarity.” (This is due to band-limited distortion, where frequencies below about 965 Hz get less and less distortion the lower they are. Tubescreamers and Rats also feature band-limited distortion.) Clipping C24 removes the band-limiting and results in a distortion I’d describe as “full.”
I recommend starting with C25, seeing what you think, then removing C24 if you want a fuller distortion sound. This does not work if you start with C24; once you clip C24 you’re done here, unless you want to solder!
C17 – Remove it with cutting pliers
Removing these components disconnect the MT-2’s gyrator EQ circuits from the rest of the pedal. These gyrator EQs are not the active EQ that has controls on the outside of the pedal; they are a hard-wired mid-boost before most of the distortion, then a hard-wired low and high boost after the distortion, and they give the Metal Zone most of its characteristic sound. You know, that (generally awful – more power to you, stock Metal Zone users! You do you) weird mid-scoop / screechy highs / odd bass bump that can’t be dialed out. Removing them turns the Metal Zone into a vanilla hard-clipper with a versatile EQ section, e.g. a pretty useful dirt pedal.
Optional no-solder mods
D3 & D4 – Remove one or both of them with cutting pliers for more volume, a different character to the distortion, and a nearly-clean sound at minimum Distortion settings
These diodes hard-clip the signal, but they are not the only part of the circuit that distorts (the opamps clip as well). Removing them sounds pretty cool to me, except that for sustained notes/chords at medium Distortion settings have a kind of abrupt transition from distorted to clean sound as they decay. Personally I leave them in unless I’m going to do some other mods (including soldering!) too.
R42 – Remove it with cutting pliers for a lot more gain (and noise), if the Distortion control maxxed out isn’t enough for you.