Envelope controlled filter is an effect type that ventures beyond the mainstream yet is equally at home in a wide range of genres and equally effective on guitar, bass, keys, horns and more. Electro-Harmonix is a pioneer in this effect category and has been making envelope controlled filter pedals since the 1970s! The Nano Q-Tron springboards off that deep heritage. Here's how it works: The Nano Q-Tron responds to the user's playing style and dynamics. The volume of the input signal it receives (also called the envelope) controls the cutoff or center frequency of a swept filter. This allows the Nano Q-Tron to create tone-altering effects ranging from subtle to dynamic, auto-wah to ultra-funky. • Vol (Volume) knob which controls the pedal's output volume. • Drive Control adjusts its filter sweep sensitivity and how the pedal responds to the user's playing dynamics. • Q Control sets the peak bandwidth of the filter and determines how subtle or dramatic the effect will be. • Mode Switch controls what frequency range the filter will pass. LP (low pass) emphasizes the lows, BP (band pass) the midrange and HP (high pass) the highs. • Pedalboard friendly, compact, rugged enclosure. • True Bypass. • Comes equipped with a 9Volt battery and can also be powered by an optional 9Volt power supply.