The Erupter is the result of over two years’ worth of tone-chasing, tweaking, and experimentation in search of what EarthQuaker president and product designer Jamie Stillman calls “the ultimate classic fuzz tone ... with a big low end, but not too mushy, a biting top end without being too harsh, and just enough output to politely send a tube amp over the top.”

In developing the Erupter, Stillman “[used] every trick [he] ever learned” to craft a fuzz Device that sounds good with any pickup type anywhere in the effects chain, even before a wah pedal, and without any impedance mismatching. To this end, the Erupter uses a buffered input section, transformer-based pickup simulation, new production 5% 1/2W carbon composition resistors, metallized polyester film capacitors, Sprague and BC electrolytic capacitors, and low-gain, hand-matched NOS silicon transistors to deliver a “well-rounded and defined fuzz tone with just enough pummeling intensity.”

The Erupter’s simple control set stands in stark relief of its rigorous design process. A single control labeled “Bias” adjusts the amount of voltage fed to the NOS silicon transistors. Low “Bias” settings yield a rude, spongy fuzz tone with plenty of sag and a blossoming attack envelope that’s gated without entering “dying battery” territory. As the “Bias” control is increased, additional harmonics stack atop the input signal, producing a stiffer, more complex fuzz tone with a tighter response, increased output, and longer sustain. The Erupter uses a fixed output level and gain setting for the “thickest fuzz possible,” and to “push the full frequency range of the guitar out front when you kick it on.”