Function f(x) The Third Rail

The Third Rail is a dual-channel overdrive pedal from Function f(x), a stompbox maker based in Elk Grove, Illinois¹. It puts two independent, discrete overdrive circuits built on NPN transistors in one box, and each channel is identical². Function f(x) calls it their first foray into the overdrive realm, with a design objective of "a versatile overdrive that could deliver a range of compression, saturation and touch sensitivity" for modern players².

The manual describes its range as broad: "It can go from a very touch-sensitive low-gain overdrive all the way up through blistering lead drive tones"³. Premier Guitar's 2015 announcement called it "a novel design that utilizes modern components for consistent performance and a long operational life," and noted it was the company's second product, a follow-up to the Clusterfuzz⁴.

Two discrete overdrive channels in one box

Most dual overdrives put two different circuits in one enclosure. The Third Rail instead gives you two copies of the same discrete, transistor-based overdrive, so the two halves behave identically and can be set up as matching boosts or as two different gain stages². Because the channels can run independently or in series, a player can use one alone, alternate between them, or stack them for what the maker describes as high gain saturation and compression².

The pedal carries laser-etched artwork on its enclosure⁵. Function f(x) positions it as a versatile overdrive rather than a clone: the Pedal of the Day review found "the sound of the drive is unique in that Function f(x) does not seem to be copying anything but rather creating their own drive with options"⁶.

The controls: six knobs and four switches

The control surface is six knobs and four toggle switches, which Premier Guitar's announcement summed up as a "wide variety of tonal options from six control knobs, four toggle switches, and three bypass modes"⁴. The two channels are identical, but their switches differ in function:

The right channel's low cut is the stacking aid: with both circuits in series, trimming the lows from the second one in the chain keeps the combined sound tighter³. The Pedal of the Day review described the same arrangement from the player's side, noting "the right channel features a low cut toggle, while the left side features a higher gain toggle"⁶.

Clipping options: Schottky, silicon or no diodes

Each channel has its own Clip switch with three positions. The manual spells out what each does³:

• Schottky diodes (left position): maximum sustain and compression
• Standard silicon diodes: a middle ground in compression and touch response
• No diodes: the transistors themselves do the work, for the most headroom and touch sensitivity

The maker frames the switch as choosing "different levels of compression, touch sensitivity and headroom"². Because the switch is per channel, the two sides can clip differently, for example a compressed Schottky channel stacked into a cleaner diode-free channel.

Footswitches and bypass modes

The Third Rail has two soft-touch footswitches for near-silent operation³, and soft touch (true) bypass with a choice of three bypass modes: one channel on at a time, toggling between each channel, or both channels on at once with momentary bypass on the second footswitch for stutter effects⁵. The pedal remembers which mode you prefer even if you unplug the power supply².

The Pedal of the Day review named the three modes and how they behave⁶:

Red mode is the stutter-effect mode the maker describes: with both channels running, the second footswitch acts momentarily, so holding or tapping it cuts or restores the sound for rhythmic effects²⁶.

Power

The Third Rail runs on a 9V DC center negative supply with a 2.1mm barrel connector, which the maker calls the industry standard⁵³. Current draw is 35mA, dropping to 20mA when bypassed⁵. At 35mA it is comfortable on most isolated power supplies and daisy chains that can spare that headroom.

Warranty and service

Function f(x) warrants the Third Rail against defective parts and workmanship for 1 year from the date of purchase, not covering damage caused by user error³. After the first year, the maker offers repair of damaged pedals either for free or for the cost of bench work depending on the issue¹. The manual adds that a full PCB replacement may take as long as 4 to 6 weeks if critical parts are out of stock, with no costs paid upfront³.

What reviewers said

Published coverage was positive. Delicious Audio called it "a high end quality box that fills the role of the popular double tube screamer option in one fell swoop," meaning it covers the same pedalboard job as running two Tube Screamer-type overdrives, in a single enclosure¹. The Pedal of the Day guest review emphasized originality, finding the drive sound unique rather than a copy of an existing circuit, with the switching modes as a major part of the appeal⁶.

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