The EF86 is a pentode rather than the common 12AX7 triode, with a higher gain factor and a larger output voltage swing. An internal converter raises the supply to 200 V for the tube, which sets the headroom of the circuit.

The pedal is meant for the end of the signal chain. Bass, Middle and Treble behave like an amp tone stack, with Level setting the output. The Boost footswitch drops the EQ out entirely for a full-range boost with its own level knob.

The headphone output and the XLR direct output both carry the analogue cab sim. A Cab Bypass switch removes it from the XLR feed for use with an IR loader, and a ground lift helps with hum. All outputs work at once, even in bypass. Only another EF86 may replace the tube.