Expresso FX Custom Dual Germanium/Silicon Fuzz with Filter Control

The Expresso FX Custom Dual Germanium/Silicon Fuzz with Filter Control is a custom fuzz pedal built around a pair of germanium transistors, with the first transistor switchable to silicon for extra versatility and stability in less than ideal ambient temperature¹. Expresso FX says the extra silicon transistor gives a fantastic alternative tone, so one pedal covers two fuzz characters without swapping units¹.

The circuit traces back to the classic Fuzz Face design: it uses the exact same NOS Philips molded metallised polyester capacitors, the "Mepolesco" type, as the original Dallas Arbiter Fuzz Face². Around those sit hand-selected NOS germanium and silicon transistors, NOS Allen Bradley carbon composition resistors, NOS Philips electrolytic capacitors and an NOS ERO KT1801 film capacitor²¹.

The controls: Volume, Fuzz, Bias and Filter

Four knobs sit on top of the pedal¹.

The Bias knob matters here because germanium transistors vary from one to another, so two pedals built the same way can behave differently. Expresso FX fits the external bias knob to help compensate for that variation, letting you set the transistors where you want them by ear¹.

The Filter control is the feature that sets this version apart from the maker's other dual fuzz builds. Expresso FX says it controls the circuit's low end, adding tremendous versatility to the pedal². In practice that means you can lean the fuzz out for a tighter, brighter sound or open it up for a fuller, bassier one, which is useful when a fuzz pedal is pushing an amp that already has plenty of low end.

Transistor options and components

Because this is a custom pedal, you choose the germanium transistor pair when ordering. Expresso FX lists three options²:

The silicon transistor is a Mullard OC202¹. Switching the first transistor to silicon gives what Expresso FX describes as a fantastic alternative tone, and it also brings stability in less than ideal ambient temperature, since germanium circuits are the ones that drift with heat¹.

The build inside the Hammond enclosure is specified in detail by the maker²¹:

• Premium Cliff UK jacks and Alpha 16mm potentiometers
• Premium 22 AWG solid core silver-plated copper wire with Teflon insulation, plus audio-grade shielded wire
• Premium Kester lead-free silver-based solder
• NOS ERO KT1801 film capacitor, NOS Philips electrolytic capacitors, NOS Allen Bradley carbon composition resistors

The enclosure is powder-coated and available in a range of finishes: Blue Shifting, Candy Lime Green, Candy Orange, Dark Gray Sparkle, Emerald Sparkle, Gold, Midnight Blue Sparkle, Purple Sparkle, Red Copper Sparkle, Translucent Brown, Translucent Copper, Translucent Matt Black and Translucent Matt White².

Power, battery and practical details

The pedal runs on an internal battery, and there is a toggle switch on the back for disconnecting the battery without having to unplug the pedal². That rear switch saves you reaching inside the enclosure when the fuzz is going to sit unused for a while.

Expresso FX covers the pedal with a 3 year warranty¹, and asks buyers to allow 7 days for shipping², consistent with a pedal built to order.

Players comparing this against the maker's other circuits can also look at the Expresso FX Custom Ge/Si Fuzz, the Expresso FX Germanium Fuzz and the Expresso FX Silicon Fuzz.

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