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Pro Co RAT

The Pro Co RAT is an effects pedal renowned for its hard-clipping , offering a versatile range of tones from subtle to saturated fuzz, and was first developed in 1978 by Pro Co Sound in . Its core circuit, designed by Scott Burnham with engineering input from Steve Kiraly, employs a single LM308 for , followed by symmetrical clipping (typically 1N4148 or 1N914 diodes) to generate a midrange-focused, harmonic-rich that cuts through mixes effectively. The pedal features three primary controls—Distortion for adjustment, (a low-pass tone control that sweeps from approximately 475 Hz to 32 kHz for treble shaping), and Volume for output level—allowing users to dial in everything from amp-like responsiveness to aggressive fuzz. Originally handbuilt in small quantities using a DIY "Bud Box" enclosure, the RAT emerged from Pro Co's basement operations, which were founded in 1974 by Charlie Wicks after the closure of the Sound Factory. Production scaled up with the "Big Box" version in 1979, transitioning to a more standardized hammered-metal housing, before the compact "" arrived in 1988 for easier pedalboard integration. An LED indicator was added in 1988, and the circuit saw a chip swap from the LM308 to the OP07 around 2002–2003 for consistency, though the fundamental design has remained largely unchanged across over 10 variants, including the Turbo (1989) with switchable LED clipping, the modern Lil' (2021), and the boutique Sterling Vermin (2025). This evolution reflects its enduring appeal, with component tolerances contributing to subtle sonic variations prized by players. The RAT's influence spans , metal, , and even genres, thanks to its "spongy" feel from the op-amp's limited (0.3 V/µs), which adds dynamic compression and complexity to the signal before clipping. Iconic users include on Nirvana's Nevermind (1991), James Hetfield on Metallica's Kill 'Em All (1983), Jeff Beck on Guitar Shop (1989), David Gilmour of , and Dave Grohl of , among others like Nuno Bettencourt and Thom Yorke. Its mid-forward tone and ability to function as a boost or clean blend have made it a staple on blockbuster albums and in live settings, cementing its status as one of the most cloned and emulated pedals in guitar history.

History and Development

Origins and Invention

The Pro Co RAT distortion pedal was invented in 1978 by engineers Scott Burnham and Steve Kiraly at Pro Co Sound in . Pro Co Sound had been founded in 1974 by Charlie Wicks following the closure of the local Sound Factory music co-op, initially specializing in sound reinforcement equipment such as speaker cabinets, cables, and stage snakes, before expanding into custom effects pedals. The pedal originated as a custom-order for local musician , built in the company's damp, rodent-infested basement workspace. During assembly, Burnham accidentally substituted a 47-ohm for a 470-ohm one in the , dramatically increasing the and producing a distinctive op-amp characterized by harmonically rich overtones. This serendipitous error formed the basis of the RAT's signature aggressive tone, which was refined into eleven initial hand-built pedals (ten singles and one double unit) using standard Bud Industries enclosures, assembled from twelve s. The device was named "The RAT" for its gritty, "rat-like" sound, evoking the basement's environment and the pedal's biting . These early prototypes marked the first commercial release of the RAT in 1978, all hand-assembled before the company's shift toward in subsequent years.

Company Evolution and Production Milestones

Following the initial development of the RAT pedal in 1978, Pro Co Sound expanded its production capabilities in the to meet growing demand for the effect. The company transitioned from the large "Big Box" production enclosure (introduced in 1979) to a more compact design in 1984, known as the "White Face" , which facilitated broader distribution and sales amid increasing competition in the effects pedal market. By 1988, Pro Co introduced the RAT2 model, featuring an updated enclosure with a Lexan/Mylar overlay, an LED status indicator, and a true-bypass switching circuit, marking a significant evolution in the pedal's manufacturability and user interface. In the , Pro Co responded to rising interest in vintage gear by launching the Big Box Vintage Reissue in 1991, a faithful recreation of the original enclosure that continued production until 2005, capitalizing on among musicians and collectors. This period also saw component updates, such as the phasing out of the LM308 op-amp by 1995 in favor of more readily available alternatives like the OP07, reflecting adaptations to supply availability without altering core production strategies. The decade's efforts underscored Pro Co's commitment to sustaining the RAT's legacy through targeted reissues rather than wholesale redesigns. The 2000s brought further reissues driven by sustained vintage demand, including the limited-edition 25th Silver Anniversary RAT in 2003 and the You Dirty RAT variant in 2004, both emphasizing commemorative production runs to engage long-time users. A pivotal shift occurred in when Pro Co outsourced RAT2 production to in , adopting a sloped enclosure design while maintaining quality oversight from its U.S. base, a move that optimized costs and global supply chains amid economic pressures. Entering the 2010s, Pro Co intensified its focus on authenticity through specialized reissue programs, such as the 1985 White Face Reissue released in , which utilized components to replicate earlier builds and appeal to purists. This era also saw branding evolutions, including the introduction of the FATRAT in 2014, which expanded the lineup while preserving the core RAT identity. In the , production faced challenges from global disruptions, prompting innovations like the 2021 launch of the Lil’ RAT, which incorporated to address component shortages and spatial constraints after a multi-year hiatus in new model development. These adaptations ensured continuity in RAT production as of 2025, balancing tradition with practical manufacturing responses to economic factors.

Design and Circuitry

Core Circuit Architecture

The Pro Co RAT distortion pedal employs a single (op-amp) as its central component, originally the LM308 , which provides the stages responsible for signal amplification and generation. This op-amp operates in a non-inverting configuration with a feedback loop that incorporates variable control via a 100kΩ , enabling adjustable levels from subtle to aggressive. The LM308's characteristics, including a of 0.3 V/µs and a gain-bandwidth product of approximately 1 MHz, contribute to the pedal's distinctive compressed and harmonic-rich tone by limiting high-frequency response during clipping. The signal path begins with an input buffer stage featuring a 1 MΩ pull-down resistor (R1) to set input impedance and a 22 nF capacitor (C1) forming a high-pass filter to block DC while passing guitar frequencies. This feeds into the op-amp configured as a single non-inverting gain stage, where hard clipping occurs via a pair of silicon diodes (1N4148 or equivalent 1N914) arranged in anti-parallel within the feedback loop to symmetrically limit the signal to the diodes' forward voltage drop (approximately ±0.7 V). The clipping diodes produce the pedal's signature square-wave-like distortion waveform, adding odd harmonics that enhance perceived brightness and sustain. Coupling capacitors, such as 2.2 µF units, isolate DC between stages to prevent offset buildup. Following the op-amp, the signal encounters the tone control, a passive RC filter network using a 100 kΩ linear potentiometer (R_TONE) in conjunction with fixed capacitors (e.g., 3.3 nF) and resistors to create an adjustable high-pass/low-pass response, with cutoff frequencies ranging from about 475 Hz (full cut) to over 32 kHz (flat response). This attenuates or emphasizes high frequencies, allowing users to dial in darker or brighter tones without affecting the core . The output stage includes a 100 kΩ audio-taper potentiometer for level adjustment, followed by a buffer using a 2N5458 to maintain and low . Specific elements like 0.68 µF coupling capacitors appear in certain iterations for inter-stage , ensuring clean signal transfer. The power supply section supports a standard 9 V DC input from a battery or external adapter, with filtering provided by a 100 µF (C11) and a 0.1 µF (C12) in parallel, alongside a 47 Ω series (R10) to decouple noise and stabilize the op-amp's supply rails. Early printed circuit boards (PCBs) were hand-etched on single-layer through-hole designs for artisanal production, evolving to more efficient in subsequent versions to improve reliability and reduce costs while preserving the circuit's . Over time, the LM308 has been substituted with equivalents like the OP07 in modern builds due to availability, though this maintains the fundamental architecture.

Operational Principles and Sound Characteristics

The Pro Co RAT generates through a combination of op-amp gain amplification and hard clipping, producing a range of effects from subtle to heavy fuzz. The core stage employs a non-inverting , typically the LM308, configured for variable gain up to approximately 67 , which amplifies the input signal while the feedback loop with a pair of silicon (1N914 or equivalent) in anti-parallel configuration clips the symmetrically at around ±0.7 V, introducing non-linearities that generate odd and even harmonics and contributing to the pedal's aggressive, harmonically rich tone. The pedal's three control knobs interact to tailor the distortion's intensity and tonal balance. The Distortion knob adjusts the op-amp's , allowing users to dial in low levels for a clean boost or high settings for fuzz-like sustain, while maintaining unity gain capability through the Volume knob, which controls the output stage without altering the distortion character. The Filter knob functions as a variable , sweeping the from about 475 Hz (fully clockwise, reducing for a darker ) to over 32 kHz (fully counterclockwise, preserving highs), effectively acting as a reverse control to shape brightness. This interaction enables precise adjustments, where higher settings pair with Filter tweaks to emphasize or tame the pedal's inherent focus. In terms of , the RAT exhibits a pronounced emphasis, with a hump centered around 1 kHz, resulting from cascaded high-pass filters that attenuate lows below 1.5 kHz and 60 Hz, combined with the op-amp's limited (0.3 V/µs) and gain-bandwidth product, which harmonics above 5 kHz. This design yields a biting ideal for crunch and lead sustain, while softened highs and controlled prevent muddiness. Compared to tube amp breakup, the RAT mimics natural through its op-amp non-linearities but adds a sharper due to the hard clipping and frequency-selective , providing a more immediate, pedal-specific response rather than gradual warmth.

Variants and Versions

Current Production Models

The Pro Co RAT2 serves as the flagship model in the current lineup, featuring a standard diode clipping that delivers the iconic hard-edged sound synonymous with the RAT series. Housed in a durable black steel enclosure, it operates on a 9V or external via a 2.1mm DC jack, with dimensions measuring 4 inches deep, 3.5 inches wide, and 2.5 inches high. This model includes the classic three-knob layout—, , and —for versatile tone shaping, from subtle overdrive to aggressive fuzz, and remains widely available through retailers like and . The Turbo RAT variant enhances the core RAT circuitry with red LED clipping diodes, providing smoother distortion and higher headroom compared to the silicon diodes in the RAT2, allowing for greater output levels while maintaining the series' characteristic scooped midrange. Introduced in 1989, it shares the same black steel enclosure, 9V power requirements, and overall dimensions as the RAT2, but offers intensified gain for players seeking more aggressive tones without sacrificing clarity. This model continues in active production and is stocked at major outlets such as and , typically priced between $80 and $120 USD alongside other standard RAT variants. The FAT RAT, introduced in 2014 as a higher-gain variant with selectable clipping for enhanced low-end thickness and versatility, builds on the classic RAT architecture but incorporates a "Thick" switch and modified op-amp biasing for more aggressive . It features a larger for improved pedalboard integration, operates on 9-18V power, and remains in active production as of 2025, available through retailers like and Reverb, typically priced between $150 and $180 USD. The Solo RAT, introduced in 2006, expands the RAT design with four controls—including a Scoop switch for midrange adjustment and a three-way clipping selector (silicon, LED, germanium)—offering greater tonal flexibility from overdrive to fuzz. Housed in a black steel enclosure similar to the RAT2, it uses 9V power and is actively produced as of 2025, available at major retailers like , priced around $100-130 USD. The Deucetone RAT, launched in 2002, features dual independent RAT circuits with selectable clipping options (, LED, no diodes) per channel, allowing stacking or operation for complex tones. It shares the standard black enclosure and 9V power setup, and continues in production as of 2025, stocked at outlets like , typically $150-200 USD. For pedalboard-conscious users, the Lil' RAT offers a compact without a battery compartment, relying solely on a 9V external through its 2.1mm jack, while employing an identical circuit to the RAT2 for consistent diode-based . Measuring just 2 inches wide—roughly half the width of the standard models—it fits the same black steel enclosure aesthetic but in a sloped, space-saving design, preserving the full range of RAT tones from clean boost to saturated fuzz. Released in , the Lil' RAT is actively produced and available at retailers like and , with pricing in the $80-120 USD range typical of the lineup. The You Dirty RAT introduces a germanium clipping configuration, imparting a warmer, more tone with vintage fuzz-like sustain—offering about 3 dB more than the original RAT design—for applications evoking 1960s aesthetics. It utilizes the familiar black steel enclosure, 9V power via battery or adapter, and shares dimensions with the RAT2, but its limited yet ongoing production emphasizes boutique appeal within the series. As of 2025, it remains obtainable through outlets including and , generally falling within the $80-120 USD price bracket for current RAT models, though occasional backorders may apply. The , originally produced from 1979 to 1983 as a bass-oriented version featuring a clean blend and effects loop for low-frequency preservation, was reissued in with fewer than a few hundred original units made. The reissue maintains the core design, including master volume, and remains in active production as of 2025 for applications, available through select retailers.

Discontinued and Limited Editions

The original Pro Co RAT, produced from 1978 to 1988, featured hand-wired construction and distinctive whiteface enclosures, contributing to its reputation for a sought-after tone characterized by the LM308 op-amp's unique and harmonic response. These early models transitioned from larger "big box" formats in the late to smaller enclosures by , with production ceasing as Pro Co shifted to blackface designs and updated circuitry to address manufacturing efficiencies. The '85 Whiteface Reissue, launched in 2010 as a limited-edition recreation of the 1980s whiteface aesthetic, faithfully replicated the original using surplus LM308 chips, 24mm potentiometers, and period-correct graphics, with production limited to approximately 100 units. It was discontinued around 2013-2014 when surplus components were exhausted, with Pro Co confirming no plans for further builds due to the unavailability of authentic parts. Overall, many RAT discontinuations stemmed from supply chain disruptions for rare components, particularly the LM308 op-amp declared obsolete by in 1993, leading to shortages that intensified in the and halted reissues reliant on NOS stock.

Modifications and Customizations

Common User Modifications

Users frequently modify the Pro Co RAT by replacing the stock 1N4148 diodes in the clipping stage with diodes, such as 1N34A types, to achieve softer clipping characteristics that enhance sustain and for a more overdrive-oriented response. Alternatively, substituting with red LEDs increases headroom, yielding a brighter tone with reduced and greater , as exemplified in the Turbo RAT design. These diode swaps alter the pedal's content without significantly changing the core op-amp distortion circuit. To counteract the original buffered bypass, which can introduce subtle tone coloration when disengaged, many owners install true switching kits paired with LED indicators. These upgrades ensure the signal passes unaffected through the pedal when off, mitigating impedance loading in complex pedalboards, while the LED provides clear on/off visibility absent in early models. Input and output additions, often implemented with low-noise op-amps like the TL071, are common to minimize "tone suck" and maintain in long chains, particularly by stabilizing impedance at the pedal's front end. The original output handles post-distortion amplification, but added input buffering prevents high-frequency loss from preceding effects.

Aftermarket and DIY Enhancements

Boutique modification services have expanded the Pro Co RAT's capabilities by incorporating professional upgrades such as switchable clipping diode options and components that reduce the noise floor for cleaner operation. For instance, Robert Keeley Electronics provides a mod that enhances dynamic range and tonal clarity while adding a Gyrator circuit for improved EQ response, particularly addressing low-end loss at higher gain settings. Similarly, Alchemy Audio's service replaces stock components with higher-quality alternatives, including a three-position gain switch for versatile distortion levels and a battery simulator to minimize hum. Hatch Guitar Works offers the "LM Pro" mod, installing the original LM308 op-amp alongside noise-reducing upgrades for a more authentic vintage tone with enhanced fidelity. DIY enthusiasts can access complete kits to build RAT clones from scratch, enabling customization during assembly. PedalPCB's Muroidea kit replicates the classic RAT circuit using modern components like the OP07 op-amp, providing true bypass via and supporting easy integration of mods such as clipping switches. Vero board layouts, popular for point-to-point wiring, are freely available on community sites; for example, tagboardeffects.blogspot.com hosts verified schematics that allow builders to incorporate tweaks like adjustable high-pass filters using trimmers. Stomp Box Parts supplies a full RAT-style with all necessary components, corresponding directly to the PedalPCB design for reliable replication. Advanced enhancements in recent DIY builds often include expansions to provide greater tonal control beyond the stock knob. Modders frequently add active 3-band sections, such as Baxandall-style circuits, allowing independent , , and adjustments to tailor the RAT's aggressive midrange for various amps and guitars. Community resources play a vital role in guiding safe implementation of these enhancements, with forums emphasizing precautions like proper grounding to prevent electrical shorts, noise, and other hazards during mods. DIYstompboxes.com features extensive RAT-specific threads, including verified layouts and troubleshooting for mods like diode swaps—such as replacing 1N4148s with LEDs for a Turbo RAT variant—alongside discussions on component sourcing and fitting. These platforms foster collaborative , ensuring builders prioritize electrical , such as using sinks on op-amps and testing circuits incrementally.

Clones and Replicas

Official Reissues by Pro Co

In 2010, Pro Co released the Limited Edition '85 Whiteface RAT reissue, an exact replica of the 1985 circuit design featuring period-correct components such as the and original-style clipping diodes to faithfully recreate the tone of the mid-1980s models. This limited run of individually serial-numbered units emphasizes its collectible appeal among enthusiasts seeking vintage authenticity without the premium of original pedals. Pro Co's modern reissues, including variants like the Big Box Reissue produced into the s, incorporate (NOS) parts such as the discontinued LM308 chip to maintain sonic fidelity to early designs, with prices typically starting at $150 or higher depending on the model and retailer. These contemporary editions, part of ongoing production lines like the RAT2 and limited color series (e.g., the Ikebe Yellow RAT2), are distributed exclusively through Pro Co's authorized dealers such as , , and Reverb, often featuring unique serial numbers for limited variants to support collector interest. While preserving the core distortion circuitry and tonal characteristics, these reissues differ from originals in practical updates, including a standard 2.1mm barrel power jack (replacing the phono-style connector) and a bottom-access compartment for easier maintenance, alongside RoHS-compliant printed boards to comply with manufacturing regulations. These modifications ensure reliability and environmental standards without altering the pedal's signature aggressive and filterable fuzz tones.

Third-Party Clones and Inspirations

The Ross Distortion, produced by Ross Audio in the late 1970s and early 1980s, was one of the first pedals to utilize a similar op-amp-based clipping circuit, delivering a gritty, mid-focused tone comparable to the early Pro Co RAT. This pedal, later reissued under / ownership, influenced subsequent designs by emphasizing versatile gain staging through diodes and operational amplifiers like the LM308. During the 1980s, DIY enthusiasts began producing kit-based clones of the RAT circuit, often using readily available components to replicate its characteristic hard-clipping , which became popular among hobbyists for its affordability and customizability. In the , third-party interpretations expanded the RAT's legacy with multi-function designs, such as the JHS PackRat, a compact pedal using a switching system to select between nine analog variations of the , including vintage and modified voicings, for seamless transitions. The Flatiron Fuzz, introduced in 2018, draws directly from the RAT2's late-1970s op-amp topology, incorporating symmetrical hard clipping for a versatile fuzz/ response that ranges from subtle to aggressive sustain. Boutique builders have further innovated on the RAT framework, with the Wampler Ratsbane (2021) offering a miniaturized high-gain version featuring a voice switch for tonal variations and a filter control to enhance clarity in dense mixes, while staying true to the original's op-amp core. Similarly, Catalinbread's Katzenkönig (2015) integrates the RAT's distortion stage with a germanium Tone Bender MkII fuzz circuit, creating a hybrid pedal that provides tight, articulate dirt with switchable modes for fuzz or distortion emphasis. Due to Pro Co's trademark protection on the RAT name, many 2020s third-party pedals adopt descriptors like "RAT-style" or "inspired by" to highlight circuit similarities without direct replication.

Cultural Impact

Notable Users and Applications

Kurt Cobain of Nirvana utilized the Pro Co RAT distortion pedal in the studio for the 1991 album Nevermind, particularly to achieve the gritty grunge tone on the track "Smells Like Teen Spirit." The pedal provided a distinct, aggressive distortion that complemented Cobain's Fender Mustang guitar and Mesa/Boogie amp setup, contributing to the raw edge of the recording. This studio application highlighted the RAT's ability to deliver high-gain, midrange-focused overdrive suitable for grunge's intense rhythm work. Dave Grohl of Foo Fighters has incorporated the Turbo RAT variant into his rig for rhythm guitar tones, notably in early band recordings and live performances. The pedal's switchable modes allowed Grohl to blend standard RAT distortion with a brighter, treble-boosted option, enhancing the drive in early Foo Fighters tracks. On stage, Grohl often positions the Turbo RAT early in his pedalboard chain to push tube amps into saturation, creating a dynamic response for alternative rock dynamics. Thom Yorke of Radiohead employs the Pro Co Turbo RAT for distortion in the band's atmospheric and experimental soundscapes, as heard across multiple albums starting from the early 1990s. The pedal's versatile gain structure enables Yorke to craft ambient textures by dialing in lower distortion levels and pairing it with delay effects on his Fender Telecaster. In studio sessions, such as those for OK Computer (1997), the Turbo RAT was used alongside other drives to layer subtle overdrive that supports Radiohead's alternative rock ethos. James Hetfield of Metallica used the Pro Co RAT on the band's 1983 debut album Kill 'Em All to achieve the aggressive, mid-forward distortion essential for thrash metal riffs, stacking it with his Marshall amps for tight, cutting tones on tracks like "Battery." The Pro Co RAT finds widespread application in punk, grunge, and alternative rock genres due to its aggressive, mid-forward distortion that cuts through dense mixes. In studio environments, it excels for tracking high-energy riffs, as seen in Nirvana's Nevermind, where it was direct-injected for controlled gain without excessive noise. On stage, musicians integrate the RAT into compact pedalboards for reliable performance, often stacking it with overdrives for varied textures in live punk and grunge sets. This dual adaptability underscores its role in both polished recordings and raw performances across these styles.

Influence on Guitar Effects and Music Genres

The Pro Co RAT pedal has profoundly shaped the landscape of guitar effects since its introduction in 1978, pioneering an op-amp-based hard-clipping circuit that delivered versatile, aggressive tones ranging from to fuzz-like . This design emphasized simplicity and modifiability, with its reversed tone filter allowing for bass-heavy responses when turned clockwise, influencing subsequent generations of pedals that prioritized tonal flexibility and midrange punch. By the , the RAT's circuit became a blueprint for op-amp s through its emphasis on high-gain versatility and ease of customization, such as resistor modifications for cleaner sounds. Its enduring legacy is evident in the proliferation of clones and variants from the to the 2020s, cementing it as a foundational element in pedal architecture. In music genres, the RAT emerged as a staple during the 1980s and 1990s, particularly in , , and emerging scenes, where its gritty, screeching cut through dense mixes. It played a key role in the movement of the early 1990s sound, providing the raw, mid-focused aggression heard in recordings that defined the era's sludgy rhythms and feedback-laden solos. In , the pedal's tight, punchy supported fast-paced riffs and palm-muted chugs, contributing to the genre's high-energy drive from the mid-1980s onward. By the 2000s, its adoption in highlighted its adaptability for lo-fi and ambient textures, often stacked with other effects for layered, atmospheric tones. The RAT's tonal profile also fueled ongoing debates in rock circles comparing it to the , with the RAT favored for its edgier, more articulate versus the Muff's woollier fuzz, influencing pedalboard stacking strategies across genres. The RAT's cultural footprint extends to industry recognition and modern media, where it remains a in pedal anthologies and pursuits. Featured prominently in discussions of effects, it underscores milestones in evolution, with variants like the Turbo RAT expanding its heavy-gain applications into contemporary metal. In the digital age, the pedal's allure drives widespread demonstrations and "tone chases," where musicians replicate classic sounds, reinforcing its status as a timeless reference for guitarists exploring 's possibilities.

References

  1. [1]
    The ProCo Rat went from basements to blockbuster albums
    Dec 12, 2024 · How the Rat changed the world of distortion for guitarists of all stripes, from hard rockers and metalheads to jazz cats, too.<|control11|><|separator|>
  2. [2]
    PROCO RAT PEDAL MYTHS, HISTORY, AND TIMELINE
    ### Summary of Pro Co RAT Pedal
  3. [3]
    ProCo Rat Analysis - ElectroSmash
    The Pro Co Rat is a distortion pedal by Pro Co Sound designed by Scott Burnham and Steve Kiraly in Kalamazoo, Michigan 1978.
  4. [4]
    What Makes the Pro Co RAT So Great? - InSync - Sweetwater
    Dec 15, 2021 · The standard Pro Co RAT is a hard-clipping distortion pedal capable of near-clean grit, ultra-saturated fuzz, and everything in between.
  5. [5]
    A Guide to the ProCo RAT | GC Riffs
    ### Origins and Invention Details of the ProCo RAT (1978 and Before)
  6. [6]
    ProCo Rat History - Griffin Effects
    ProCo Rat History ; Big Box Rat - Version 1 1979-81 · Roadkill 1997-2001 ; Big Box Rat - Version 2 1981-83 · Deucetone Rat 2002-Present ; Small Box Rat 1984-88 ...
  7. [7]
    LM308 Chip: The Silicon Heart of the ProCo RAT | Equipboard
    Dec 23, 2024 · The development of the RAT distortion can be traced back to the late 1970s at ProCo Sound in Kalamazoo, Michigan. Scott Burnham and Steve Kiraly ...<|control11|><|separator|>
  8. [8]
    Proco Rat - Guitar FX Layouts
    Jan 29, 2012 · I put this into a 1590BB and also included BMP Tone Control circuit with a separate footswitch after the Rat's circuit. I use the BMP as ...
  9. [9]
    Pro Co RAT 2 Distortion Pedal - Sweetwater
    In stock Rating 4.5 (218) This distortion pedal boasts the same 3-knob layout as its vintage counterparts, along with a rugged on/off footswitch, a stylish "A" status LED, and eye- ...Missing: models | Show results with:models
  10. [10]
    ProCo RAT2 Distortion Effects Pedal | Guitar Center
    With a straightforward 3-knob layout controlling distortion amount, filter and volume, this pedal is easy to dial in but capable of a surprisingly wide range ...
  11. [11]
    Pro Co Turbo RAT Distortion Pedal - Sweetwater
    In stock Rating 4.5 (7) Pro Co has the solution to your conundrum: the Turbo RAT. This dirt pedal houses a modified RAT circuit, utilizing red LEDs instead of silicon clipping diodes.Missing: current | Show results with:current
  12. [12]
    ProCo Turbo Rat Distortion | Reverb
    Year. 1989 - 2025 ; Made In. United States ; Overview. Featuring an LED display, traditional RAT filter control for nuanced brightness control and double the ...
  13. [13]
    Pro Co Lil' RAT Distortion Pedal - Sweetwater
    Jun 15, 2021 · The Pro Co Lil' RAT packs a full-blown RAT 2 into a micro-sized stompbox. The Lil' RAT offers all the tone and functionality of its larger predecessor.<|separator|>
  14. [14]
    Lil' RAT Pedal
    ### Pro Co Lil' RAT Specs Summary
  15. [15]
    ProCo to Announce The Lil' Rat, A Mini Iteration of the Acclaimed Rat 2
    Feb 15, 2021 · After being introduced in 1978, the original ProCo Rat has received several iterative changes over the years. Current production models ...
  16. [16]
    You Dirty RAT - ACT Entertainment
    30-day returnsThis pedal is the perfect middle ground between distortion and fuzz, combining the characteristic cutting RAT tone with the warmth of a classic fuzz-tone.
  17. [17]
    Pro Co You Dirty RAT Distortion Pedal - Sweetwater
    Go ahead and place your order and we'll follow up shortly to let you know when to expect it. Estimated December 2025. Add to Cart. No Hassle Return Policy.Missing: current | Show results with:current<|separator|>
  18. [18]
    Pro Co Limited Edition Reissue '85 Whiteface RAT
    May 18, 2013 · This product is an authentic reproduction of the original, using the discontinued LM308N chip sourced from surplus, the original 24mm pots, and ...
  19. [19]
    When did Proco stop production of the '85 Whiteface RAT Reissue?
    Jun 26, 2014 · Been looking around at Proco's new FAT RAT and am surprised to find that the '85 RAT Reissue is no longer available 'new'.
  20. [20]
    Four Knob Rat - beavis audio research
    The Four Knob Rat (FKR) is a modified Proco Rat with true-bypass, multiple clipping options, a Ruetz mod, and a feedback loop clipping section.
  21. [21]
    Rat with even more gain? | PedalPCB Community Forum
    May 3, 2020 · It has an additional gain stage, so you can get a shit-ton of gain by changing a few resistors. If this is something you might be interested in, ...TUTORIAL - Muroidea - Proco RatFavorite Rat Mods?More results from forum.pedalpcb.comMissing: fourth | Show results with:fourth
  22. [22]
    Keeley ProCo Rat Mod - What To Know & Where To Buy | Equipboard
    Rating 4.5 (3) · $4.90 delivery2 days ago · The Keeley ProCo Rat Mod features a 3-way toggle switch that provides different clipping options, enhancing the pedal's versatility. This mod ...
  23. [23]
    Modify your Pro Co Rat Distortion with upgrades! Mod service Only!
    The service includes higher quality components, a three-position gain switch, a battery simulator, LED, new knobs, jack cleaning, and a 2.1mm power jack.
  24. [24]
    ProCo RAT "LM Pro" Mod - Hatch Guitar Works
    In stock 30-day returnsHGWFx will modify the circuit using high quality components for reduced noise and higher fidelity - We also install the coveted LM308 IC* to give you the period ...
  25. [25]
    Muroidea (ProCo Rat) | PedalPCB Community Forum
    Feb 19, 2024 · The bypass mechanism is a relay-based true bypass circuit that uses a CMOS Schmitt trigger inverter (CD40106 or 74HC14) to maintain state and ...<|separator|>
  26. [26]
    "RAT" Style DIY Distortion Pedal Kit - Stomp Box Parts
    In stockAll the parts needed to build your very own overdrive/distortion pedal, similar to a RAT! These parts are directly corresponding with the PedalPCB 'Muroidea' ...Missing: vero layout
  27. [27]
    Who knows the real trick to get more bass? (RAT) - Madbean Pedals
    Sep 3, 2018 · If you want more control over EQ, you can build an Idiotbox Blowerbox, which is a Rat with a Baxandall/James tonestack, giving you treble and ...<|separator|>
  28. [28]
    'III'. (Proco Rat with active 3 band EQ and clipping options). - Reddit
    May 3, 2023 · The 'III' is a modified Rat circuit with an active 3 band EQ so you can achieve all kinds of tones with different guitars/amps/rigs.Missing: fourth | Show results with:fourth
  29. [29]
    ProCo Rat Modifications - DIYstompboxes.com
    Mar 24, 2007 · Replacing the diodes with LEDs turns it into a Turbo Rat, which is more like an overdrive. You get less distortion, more volume.<|control11|><|separator|>
  30. [30]
    New vero layout: ProCo RAT - Page 2 - DIYstompboxes.com
    Feb 13, 2009 · The 1M drive pot will greatly increase gain. Use 100K if you can, if not use resistors in parallel to lower the pots value. My DIY site:Missing: kit | Show results with:kit
  31. [31]
    ProCo Limited Edition '85 Whiteface RAT Pedal Review
    Rating 4.5 · Review by Brian BarrJun 3, 2010 · The RAT is a very straight-forward stompbox with three controls: Distortion, Filter and Volume. The RAT's Distortion really gives you three different types of ...Missing: 2010-2020 component shortages
  32. [32]
    ProCo Rat Big Box Reissue with LM308 Chip - Reverb
    Rating 4.8 (19) Vintage Rat Big Box Reissue with Battery Door and LM308 Chip 1991-2003 Black Includes material, year, finish
  33. [33]
    ProCo Ikebe Limited Edition Rat 2 | Reverb Canada
    In stock Rating 5.0 (3) It is not an expensive pedal but all so very versatile and has stood the test of time. No cons whatsoever. 2022-09-27. Helpful. Report.
  34. [34]
    Buying Guide for the ProCo Rat Distortion Pedal | Reverb
    While the audible differences are not hugely apparent to most, many consider the newer chip to sound a bit brighter and clearer. Others prefer the warmth of the ...<|control11|><|separator|>
  35. [35]
    Ross R-50 Distortion - What To Know & Where To Buy | Equipboard
    Some users consider replacing more common pedals like the RAT clone or Boss BD-2 with the Ross R-50 due to its unique sonic characteristics. Source. Use ...
  36. [36]
    Vintage Proco Rat vs vintage Ross Distortion - YouTube
    Jan 28, 2018 · I compare an '87 rat to a late '70s/early '80s Ross Distortion.Missing: clone | Show results with:clone
  37. [37]
    DIY Rat Clone Distortion Guitar Effect Pedal - the Dead RAT
    I used some thin gauge sheet metal to fabricate a bracket for the PCB mount that connects to the case via the center pot in order to not have to add any more ...Missing: evolution hand-
  38. [38]
    https://reverb.com/ca/p/proco-ikebe-limited-edition-rat-2
  39. [39]
    Flatiron Fuzz - Electro-Harmonix
    Extremely versatile, classic op-amp powered fuzz/distortion inspired by the RAT2™! $85.30.
  40. [40]
    Ratsbane - Wampler Pedals
    In stock Rating 5.0 (8) The Ratsbane is a high-gain distortion pedal with light overdrive to fuzz, a filter control, and a gain switch with three options. It also has a voice switch.
  41. [41]
    https://www.youtube.com/watch?v=m7pryumWDuk
  42. [42]
    32 Favourite Compact Rat Style Distortion Pedals - 2024 Ultimate ...
    Aug 30, 2024 · This has long been a favourite Rat of mine with its superb mix of Soft and Hard Clipping and extra Fat control. Some of the more recent pedals ...Missing: current | Show results with:current<|separator|>
  43. [43]
    Kurt Cobain's Pedals: The Effects Behind Nirvana's Sound
    Feb 21, 2025 · Pro Co Rat. While not a regular part of Kurt's setup, the Pro Co Rat distortion pedal made an appearance on “Nevermind,” specifically on the ...
  44. [44]
    Steal the Sound: Kurt Cobain - Gear4music
    Jul 28, 2022 · The ProCo Rat was only used in the studio for Nevermind and it offered a different type of distortion to the Boss DS-1. With the album heavily ...Kurt's career · Guitars · Amplifiers · Effects pedals
  45. [45]
    What Gear Did Kurt Cobain Use on Nevermind? Guitars, Amps ...
    Oct 17, 2025 · The main guitar tone came from a ProCo Rat pedal, which was split into two signals, one running into an amp and the other straight into the ...<|separator|>
  46. [46]
    Fretprints: Dave Grohl - Vintage Guitar® magazine
    After Wasting Light, his amp array included a 100-watt Fender Tonemaster head and Hot Rod Deluxe. In early Foo Fighters, Grohl favored a ProCo Turbo Rat ...
  47. [47]
    Dave Grohl's Guitar Rig, Gear & Pedalboard | Equipboard
    $$4.90 delivery... Wasting Light," as seen in the Foo Fighters' live session at Studio 606 on YouTube. more. Find it on: Reverb Sweetwater ...
  48. [48]
    Pro Co RAT - What To Know & Where To Buy | Equipboard
    Rating 4.5 (239) · Free deliverythis pedal gives you the fuzz of Dave Gilmour, the hard grunge of Kurt Cobain and Dave Grohl, as well as the 80's distortion of Nuno Bettencourt. Easy to dial ...
  49. [49]
    Thom Yorke's Guitar Pedals and Effects - the King of Gear ;
    But by 1993, Thom had switched to a Proco Turbo Rat. Thom probably got the Turbo Rat around the time that the band were signed, so he may have initially stopped ...
  50. [50]
    The Gear of Radiohead's "OK Computer" | Reverb News
    Jun 16, 2022 · ... Thom and Jonny on their Teles respectively using a ProCo Turbo Rat and a Marshall Shredmaster for distortion. According to Nigel, the ...
  51. [51]
    Pedal Spotlight: Turbo Rat - the King of Gear ;
    Mar 27, 2012 · The Turbo Rat is a rather unique sounding distortion pedals which can be heard on a great deal of Radiohead's recordings.
  52. [52]
    Pro Co RAT 2 Distortion Pedal Reviews - Sweetwater
    In stock Rating 4.5 (218) The Pro Co Rat 2 does anything from subtle boosting up to some of the raunchiest fuzz you could ask for.
  53. [53]
    The Humble Gear Used By Kurt Cobain on Nirvana's 'Nevermind'
    Jan 9, 2024 · ” A ProCo RAT distortion pedal was also allegedly used on some songs on the album. In the same interview, Vig shed some light on the ...
  54. [54]
    RAT Distortion Pedal Guide: Settings & Top 2025 Picks | Equipboard
    Oct 17, 2025 · The Pro Co Turbo RAT gives you LED clipping at a similar price point for more output and aggression. The Pro Co FAT RAT provides switchable op- ...
  55. [55]
    Pro Co RAT 2 Distortion Settings and Tone Tips - Guitar Chalk
    Dial distortion knob based on amp gain—lower for high-gain amps, higher for clean amps. Adjust the Filter knob carefully—clockwise cuts treble, counter- ...
  56. [56]
    Is This the Best Distortion Pedal of All Time? History of Pro Co RAT
    Jan 4, 2021 · Known for the wide range of distortion tones it can cover, the RAT was first released as a custom product in 1978 by Pro Co.
  57. [57]
    RAT RACE: Ten Guitarists who love the ProCo RAT! - Sound Affects Premier
    ### Summary of Pro Co RAT Influence and Notable Users
  58. [58]
    Big Muff Vs. Rat: Which One Is Better? - Ultimate Guitar
    Apr 17, 2022 · When it comes to a great rock distortion tone, no two pedals have contributed more to the field than the EHX Big Muff and ProCo Rat.
  59. [59]
    Best distortion pedals 2025: Our top 11 high-gain stompboxes
    Jun 14, 2024 · Developed in 1978, and mass produced from 1979 onwards, the ProCo RAT has a decent claim to being the first proper mass-market distortion box.