Expresso FX Fuzz Bender Mk I.V

The Expresso FX Fuzz Bender Mk I.V is a germanium fuzz pedal that Expresso FX describes as "an accurate replica of the dual-transistor-based fuzz circuit of the Bender family"¹. That circuit is the Tone Bender Mk1.5, the two-transistor member of the British Tone Bender line, and the pedal is built with hand selected NOS (new old stock) germanium transistors and vintage-style parts throughout².

For a player, the appeal is a vintage fuzz voice with modern build quality. Expresso FX positions the pedal in its Mojo Series, a range built around rare, sourced NOS components³, and it carries a three year warranty³.

The circuit and how it compares to a Fuzz Face

The Mk I.V sits in an interesting spot among classic fuzz circuits. The manual explains that although the schematic looks familiar, the parts values set it apart²¹:

Expresso FX manual²

On where that puts the pedal tonally, the manual is specific:

Expresso FX manual²

So a player comparing fuzzes gets something between the two most famous British circuits: more body and edge than a Fuzz Face-style pedal, but without the harder attack of the three-transistor MkII design. Expresso FX also makes a Fuzz Bender MkII for players who want that other circuit, and a Fuzz Bender Mk I family recreation of the earliest three-transistor Bender circuit²⁴⁵.

Components and build

The Mojo Series parts list is the heart of the pedal's identity. Expresso FX says it has "sourced an amazing stock of rare and highly sought after NOS co[mponents]" for the range³, and the Mk I.V uses them throughout:

The manual notes that the specific transistor types currently used are listed on the Expresso FX website². The enclosure is aluminum, powder coated in a Blue Hammerite finish².

The external bias knob

Germanium fuzz circuits are sensitive to temperature and transistor characteristics, and bias (the operating voltage set on the transistors) is what keeps them sounding right. Some versions of the Mk I.V bring this out as an external bias knob, which the manual covers directly²:

• The stock setting is 12 o'clock.
• Turning it clockwise increases the bias voltage.
• Turning it anti-clockwise decreases it.
• The range is deliberately limited, so the knob corrects bias in less than optimal conditions rather than allowing extreme settings.

For a player, this means the pedal can be dialed back to its intended voice on a hot stage or a cold rehearsal room without opening the enclosure. Versions without the external knob have the bias set internally².

The Mini version

Expresso FX also builds the Fuzz Bender Mk I.V "Mini", a smaller enclosure version of the same pedal. The maker describes it as "a mini version of our Fuzz Bender Mk I.V, with exactly the same components and same classic tone"⁶. Despite the smaller box, it keeps the vintage-inspired build: point-to-point construction, top-drawer NOS components, hand-selected NOS germanium transistors, Bourns trimpots, Switchcraft jacks and lead free silver-based solder⁶. It is true bypass⁷.

Warranty and service

The Mk I.V carries a 3 year warranty³. The manual spells out what it covers: faults and damage developed by the product itself, not those caused by misuse or user error². Warranty work starts with an email to support@expressofx.com to troubleshoot the problem, followed by a Return Authorization if the pedal needs to come back².

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