The ZVex Mastotron Effects Pedal, another in the Vextron series, is a heavy silicon-based fuzz pedal with a lot of controls - volume, tone, pulse width, fuzz, and relax/push. The relax/push controls the input impedance to the pedal. The guitar effects pedal knobs let you adjust for quieter pickups, or softer guitars, and turn it towards the relax setting as you put in active pickups, and turn it all the way to the relax setting for special effects and for line-level signals if you are re-amping a bass off a recorded track. The Mastotron's fuzz control is a wide control over the fuzz depth. Pulse width control goes from a narrow pulse all the way to a nearly square wave pulse. The tone control shaves off the high end. A sub switch lets you set how many subs you have with a "2-1-3" arrangement while the dedicated volume knob controls how loud the guitar pedal gets.
Plug your guitar (or any effect's output) into the input jack. Plug the output into an amp or other effect's input. Set the amp for a warm clean tone on bypass. Turn on the pedal and rock out. Using a guitar or bass, turn the Relax/Push knob down a bit if you need to until the fuzz sounds immediate and tight. Turn the Vextron Mastotron's fuzz control until you're happy, and set the PW to square (counter-clockwise). Adjust the tone for the treble amount you want, and use the sub switch on 3 for full heavy subs for bass or 2 if the subs are overloading your amp.
Set your amp on your favorite clean tone for the most blistering results, while a distorted sound can be very cool as well. Play it into your favorite distortion pedals or direct into the amp for different textures. Try putting weird effects into the ZVex Mastotron pedal and adjust the Relax/Push knob for best interfacing.
If the performance of your fuzz pedal seems diminished or the LED becomes very dim, it's time to change your battery. Remove the four screws on the bottom of the effect pedal and carefully remove and replace the old battery, putting it back exactly in the center of the pedal on edge so that it is gripped tightly by the lid when it is screwed back in place.