Mosrite Fuzzrite

The Mosrite Fuzzrite is a fuzz pedal designed by Ed Sanner and built by the Californian guitar company Mosrite from 1966 to 1968¹². It came about after a request from the rock instrumental group The Ventures, and it exists in two distinct circuits: an early germanium-transistor version of which only about 250 units were made, and a later silicon-transistor version that was much more widespread³⁴⁵. Mosrite went bankrupt in late 1968, formally ceasing business by 1969, which ended Fuzzrite production²⁶.

For a player, the Fuzzrite is one of the classic two-transistor fuzzes of the 1960s, sitting just behind the Tone Bender, Fuzz Face and Big Muff in historical popularity⁷. Its signature control is the Depth knob, which blends a second gain stage into the first, letting the pedal move from thin, trashy fuzz to a thicker, ripping tone. Premier Guitar's reviewer placed its character plainly: "it's not as flexible as a Fuzz Face, as meaty as a Muff, or as detailed and defined as a Tone Bender"⁵.

How it works: two transistors and a Depth control

Like any Fuzzrite circuit, it is a simple affair: apart from the two transistors at the heart of the circuit, there are probably no more than a dozen additional components on the board⁵. Catalinbread, whose recreations are traced from original units, describes the circuit as two simple, separate gain stages, with the Depth knob acting as a mix control between them¹⁴.

You never hear the second stage by itself; the knob sweeps between "1" and "1+2"¹⁴. Gearnews describes the same behavior in the Catalinbread recreation: "the Depth knob then mixes in a second transistor gain stage with the first"³. Delicious Audio's buying guide notes that this design let the original "go from trashy" thin fuzz to fuller drive as the second stage comes in¹⁰.

The Volume control sets the output level of the circuit. Catalinbread notes that higher Volume settings will begin to overdrive your amplifier, which can add body and smoothness to the fuzzed-out sounds¹⁵.

Two details of the tone are built into the circuit. First, the signal travels directly through a small capacitor which cuts the low end no matter where the Depth control is set, which is why original Fuzzrites sound thin by modern standards¹⁵. Second, at low Depth settings the fuzz turns sputtery and gated: Premier Guitar's reviewer found you "can enhance the cool, sputtery gated-fuzz effects by setting the depth (gain) control to lower levels"⁵. Catalinbread's Germanium Fuzzrite adds a Modern/Vintage toggle that switches both output capacitors from 2nF to 10nF, increasing the amount of low end passing through¹⁵.

Compared with its contemporaries, the Fuzzrite is sparser than most. The Fuzz Face circuit uses two transistors, four resistors, three capacitors and two controls¹⁶, and the Fuzzrite's blend-based Depth control works differently from a Fuzz Face's Fuzz knob, which sets the amount of fuzz directly.

Germanium and silicon versions

From 1966 to 1968, Mosrite produced two distinct fuzz circuits, one outfitted with silicon transistors and the other with germanium components³. The germanium version came first, and the silicon version appeared in the late '60s, replacing it⁵².

The germanium version

Earlier Fuzzrites were built with a set of 2N2613 and 2N408 germanium transistors². Travis, who traced an original germanium Fuzzrite for the Guitar FX Layouts site, suggests transistor gains of roughly 100 to 150 for the first transistor and 40 to 60 for the second¹⁷. He described the sound of his original pedal, quoting builder Don Baker: "it has a big, fat, musical sound at some of the lowest gain and lower volume settings. And of course it rips at full gain"¹⁷.

The germanium version went through several construction phases, documented by the Fuzzboxes history site²:

Ed Sanner estimated that around 250 germanium models were produced between 1966 and 1968, which makes the germanium Fuzzrite by far the rarer of the two circuits³⁴. Premier Guitar reported the same figure, with "original designer and Mosrite employee Ed Sanner estimating that around 250 ever made it out the door"¹¹.

The silicon version

In 1968 the germanium-transistor Fuzzrite was discontinued and replaced with a silicon-transistor version of the same circuit². Aion FX, whose Orpheus projects document both circuits, notes that "the silicon version seems to have been much more widespread"¹². In that final year of production, Mosrite shifted exclusively to silicon parts⁷. One 1968 variant was built by a combination of Mosrite and Sprague, with the circuits encased in orange Sprague "modules"; date codes show Sprague supplied them from July 1968 to at least October 1968².

Even among Fuzzrite fans, divisions over the merits of germanium and silicon versions persist⁵.

The Fuzzrite's afterlife: Guild, Foxey Lady and the Axis

The silicon Fuzzrite's circuit outlived Mosrite itself through OEM deals. Aion FX notes the silicon version "was whitelabeled or cloned as the Orpheum Fuzz, Guild Foxey Lady, and Electro-Harmonix Axis Fuzz"¹².

Out of Mosrite's bankruptcy sprang Sierra Electronics, a partnership that released the Nu Fuzz, designed by Ed Sanner; the Nu Fuzz featured a tone filter control instead of the Depth control².

Pedals based on the Fuzzrite

Because original Fuzzrites are rare, the circuit survives mainly through recreations and adaptations. Delicious Audio ranks the Mosrite Fuzzrite among the "second" most popular historical fuzzes, after the holy trinity of Tone Bender, Fuzz Face and Big Muff, which explains the number of builders who have taken it on⁷.

Catalinbread's Germanium Fuzzrite, released in 2022, features two NOS PNP germanium semiconductors, like Mosrite's original germanium Fuzzrite⁴. Its M/V toggle's Modern position restores low end the original circuit cuts¹⁵. Wilson Effects' Kevin is candid about how far his pedal has drifted: "So originally the NotRight was based on the Silicon version of the FuzzRite pedal," while the current version is its own circuit, with a Depth knob he describes as "actually an intensity knob but hey depth also works right?"²⁰.

For DIY builders, Travis's vero layout for the germanium Fuzzrite matches his original pedal's component values, with an added voltage inverter for easy daisy chaining; he specifies a nominally 350k reverse depth pot (a C500K pot with a 1M2 resistor between lugs 1 and 3 can be substituted) and a 500K volume pot¹⁷. One quirk he found in his own pedal: a 25uF cap soldered from one ground pad to another, doing nothing in the circuit¹⁷.

Who played one

The Fuzzrite's best-known user is Davie Allan, whose fuzz-era "hairy tones," in Dan Epstein's telling for EarthQuaker Devices, came from a Mosrite Fuzzrite²⁶. General Guitar Gadgets' product page reports that the Fuzzrite was used by Eric Brann of Iron Butterfly on the classic song "In-A-Gadda-Da Vida"²⁵; the claim is reported rather than confirmed.

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