--- title: "ProCo RAT Pedal Guide: RAT 2, Variants, Used Versions, and Alternatives" id: "508" type: "post" slug: "pro-co-rat" published_at: "2026-09-28T17:16:00+00:00" modified_at: "2026-09-28T02:16:39+00:00" url: "https://signal.resyn.com/effects-pedals/pro-co-rat/" markdown_url: "https://signal.resyn.com/effects-pedals/pro-co-rat.md" excerpt: "The ProCo RAT 2 is still the easiest place to start with the RAT family. It gives you the core three-control circuit, the familiar Filter behavior, and enough gain range to move from gritty boost into dense distortion and fuzz-like..." taxonomy_category: - "Effects & Pedals" --- [Effects & Pedals](https://signal.resyn.com/topics/effects-pedals/) # ProCo RAT Pedal Guide: RAT 2, Variants, Used Versions, and Alternatives - Resyn - September 28, 2026 Summarize with AI:[ChatGPT](https://chat.openai.com/?q=Summarize+the+content+at+https%3A%2F%2Fsignal.resyn.com%2Feffects-pedals%2Fpro-co-rat%2F+-+%2A%2AResyn+helps+musicians+buy%2C+sell%2C+trade%2C+compare%2C+and+understand+musical+instruments+and+professional+gear.%2A%2A) [Google AI](https://www.google.com/search?udm=50&aep=11&q=Analyze+and+summarize+the+key+insights+from+https%3A%2F%2Fsignal.resyn.com%2Feffects-pedals%2Fpro-co-rat%2F+-+%2A%2AResyn+helps+musicians+buy%2C+sell%2C+trade%2C+compare%2C+and+understand+musical+instruments+and+professional+gear.%2A%2A) [Claude](https://claude.ai/new?q=Summarize+the+content+at+https%3A%2F%2Fsignal.resyn.com%2Feffects-pedals%2Fpro-co-rat%2F+-+%2A%2AResyn+helps+musicians+buy%2C+sell%2C+trade%2C+compare%2C+and+understand+musical+instruments+and+professional+gear.%2A%2A) [Perplexity](https://www.perplexity.ai/search/new?q=Provide+a+comprehensive+summary+of+https%3A%2F%2Fsignal.resyn.com%2Feffects-pedals%2Fpro-co-rat%2F+-+%2A%2AResyn+helps+musicians+buy%2C+sell%2C+trade%2C+compare%2C+and+understand+musical+instruments+and+professional+gear.%2A%2A) [Grok](https://x.com/i/grok?text=Please+summarize+this+article%3A+https%3A%2F%2Fsignal.resyn.com%2Feffects-pedals%2Fpro-co-rat%2F+%7C+-+%2A%2AResyn+helps+musicians+buy%2C+sell%2C+trade%2C+compare%2C+and+understand+musical+instruments+and+professional+gear.%2A%2A) [Add Us as a Preferred Choice](https://www.google.com/preferences/source?q=https://www.resyn.com/) The ProCo RAT 2 is still the easiest place to start with the RAT family. It gives you the core three-control circuit, the familiar Filter behavior, and enough gain range to move from gritty boost into dense distortion and fuzz-like saturation. But “a RAT” no longer means one box. The current RAT line includes eight models, ranging from the compact Lil’ RAT to the dual-channel Deucetone and newer Sterling Vermin. This guide separates the changes that matter from the collector mythology. The goal is simple: understand the standard RAT 2 first, then decide what you actually need to be different. ## What Is a RAT Pedal, and Why Is the RAT 2 the Reference Point? A RAT is a hard-clipping distortion circuit built around a variable-gain op-amp stage. ACT’s technical overview describes the classic circuit as a single op-amp feeding clipping diodes to ground, with enough gain inside the op-amp stage that clipping begins before the signal reaches those diodes. The RAT 2 is the practical reference because it preserves that core formula without asking you to choose extra modes first. It remains a current production model and serves as the simplest baseline for understanding the rest of the family. ### Distortion, Filter, and Volume The controls look simple because they are simple. **Distortion** controls gain in the op-amp circuit. More clockwise rotation increases the amount of overdrive. **Filter** is the tone-shaping control, but it works opposite the direction many guitarists expect: clockwise rotation cuts more treble. **Volume** controls the pedal’s total output level. That reversed Filter behavior is one of the RAT’s most useful ideas. Instead of treating the knob like a conventional treble control, think of it as a high-cut: turn clockwise when the rig gets sharp, and counterclockwise when you need more bite. ### From Dirty Boost to Heavy Distortion and Fuzzier Saturation The RAT does not live in one gain category. Its own owner’s instructions present three starting points: a softer blues-style distortion, a biting lead sound with strong harmonic emphasis, and a heavy setting built around sustain. That range explains why players describe the RAT using overdrive, distortion, and fuzz language in the same conversation. At lower Distortion settings, the RAT adds grit without demanding that every note become heavily saturated. Move further up the control and the compression and harmonic density become much more obvious. Near the top, the response becomes thick enough to overlap with fuzzier textures, even though the RAT remains fundamentally a distortion design. ## Which ProCo RAT Model Fits Your Rig? Start with the RAT 2 unless you can name the specific thing you want changed. | Model | What changes | Best fit | | --- | --- | --- | | RAT 2 | Core three-control RAT format | Players who want the standard reference point | | Lil’ RAT | RAT 2 controls and tone in a two-inch-wide enclosure | Crowded pedalboards and compact rigs | | Turbo RAT | Alternate clipping architecture associated with greater headroom and a more open response | Players using the RAT as a louder drive or less-compressed distortion | | You Dirty RAT | Alternate clipping associated with a denser, more compressed response | Players wanting a more saturated RAT feel | | FAT RAT | Bass-enhancement circuit plus switchable clipping | Players wanting more low-end and clipping control | | Deucetone RAT | Two independent RAT channels with multiple voices | Stereo rigs, stacked RAT sounds, and complex boards | | Solo | Expanded tone shaping and selectable clipping | Players wanting more EQ control than the standard layout | | Sterling Vermin | LM741 op-amp with selectable silicon/BAT41 clipping | Players wanting a newer boutique interpretation of the RAT concept | The family differences above combine current ACT product information with documented circuit-history research where the present manufacturer pages do not expose deeper component detail. ### RAT 2 – The Baseline The RAT 2 is the model to buy when you want to understand the RAT rather than shop around it. You get Distortion, Filter, and Volume. That is enough to learn how the circuit reacts to your guitar and amp, and it makes later comparisons easier because every other RAT begins with something you already understand. This simplicity matters in the used market too. Once the RAT 2 becomes your reference, extra clipping modes, expanded EQ, vintage components, or dual channels become concrete differences rather than feature-list noise. ### Lil’ RAT – RAT 2 Functionality for a Smaller Board The Lil’ RAT exists for a practical reason: space. ACT describes it as delivering the same controls, tone, and functionality as the RAT 2 in a two-inch-wide enclosure. It also uses rear-mounted audio jacks and a standard 2.1 mm barrel power connection. So the choice between RAT 2 and Lil’ RAT is mostly physical. Want the traditional enclosure? Start with the RAT 2. Need every inch of pedalboard space? The Lil’ RAT solves that problem without turning the purchase into a different tonal category. ### Turbo RAT, FAT RAT, and You Dirty RAT The Turbo RAT changes the clipping behavior rather than redesigning the entire concept. ACT still lists it as a current model, while JHS’s extensively researched RAT timeline traces its 1989 design to LED clipping, documenting greater headroom and a more open response than the traditional silicon-clipping RAT circuit. That makes the Turbo interesting when you like RAT texture but want the signal to stay less compressed as output rises. The FAT RAT goes somewhere else. ACT says it uses the Whiteface Reissue platform, then adds a bass-enhancement circuit and switchable clipping section. JHS documents a MOSFET arrangement among those expanded clipping options. That low-end flexibility matters when the standard circuit feels too fixed. Downtuned rigs, bass-heavy amplifiers, and players who simply want more control over how the bottom end behaves have a clearer reason to investigate the FAT RAT. The You Dirty RAT favors saturation. JHS’s historical research documents the Dirty circuit beginning with germanium 1N34A clipping diodes, followed later by BAT41 Schottky parts after germanium components became harder to source. The described result is more compression and saturation than the traditional RAT or Turbo branch. The useful distinction is simple: if the Turbo branch interests you because it opens the circuit up, the Dirty branch goes the other direction. ### Deucetone RAT and Other Current Specialty Models The Deucetone is two RATs in one enclosure, not simply a RAT with extra knobs. ACT describes two independent channels that can operate separately, in stereo, or cascaded. Channel A provides Vintage, Turbo, and Dirty voices. Channel B provides Vintage, Turbo, and Clean RAT modes, with the Clean option removing the conventional clipping role for boost-oriented use. That makes the Deucetone less of a first RAT and more of a RAT workstation. The Solo moves further away from the classic three-control layout. JHS documents a four-control design using selectable clipping alongside separate Scoop and Tone shaping. Then there is the Sterling Vermin. ACT brought the Sterling Vermin to NAMM 2026 as a boutique RAT-family design using an LM741 op-amp and selectable clipping between traditional silicon diodes and BAT41 diodes. It also uses CTS pots and a polished stainless-steel enclosure. Its role is not vintage reissue. It is a modern RAT interpretation intended to stretch the basic idea across articulate lower-gain sounds and heavier distortion. ## Buying a Used or Vintage RAT: Which Differences Actually Matter? Vintage RAT shopping gets complicated because cosmetic changes, circuit revisions, production changes, and collector language all overlap. You do not need to memorize every sub-version. You need enough history to identify what you are looking at, understand what materially changed, and avoid paying a premium for a story the hardware does not support. ### The Major RAT Eras Without the Collector Rabbit Hole The first production RAT appeared in 1979 with a Tone control rather than the later Filter arrangement. JHS’s documented timeline places the Filter-control revision in 1981, when the control direction changed so clockwise movement removed more treble. The enclosure became smaller during the mid-1980s, and the RAT 2 arrived in 1988 with an LED status indicator while retaining the established core distortion circuit. The Turbo RAT followed in 1989 with a more substantial clipping change. Later models expanded the architecture instead of replacing it. The Deucetone turned the idea into a dual-channel format. You Dirty RAT explored another clipping voice. FAT RAT added bass and clipping controls. Lil’ RAT compressed the RAT 2 concept into a much smaller enclosure. That is the useful map. Collector-level revisions exist inside those periods, but they matter most when originality, rarity, and resale value are part of the purchase. ### Why Serial Number Alone Cannot Date a RAT Do not date a used RAT from the serial number alone. ACT explicitly says there is no accurate method for dating a RAT by serial number alone and recommends using the broader family timeline to determine general age. That means useful identification needs several clues working together: enclosure shape, graphics, control labels, LED configuration, jacks, circuit board, components, and production details. If the seller is asking vintage money, photographs matter. Ask for the front, back, bottom plate, battery compartment, internal circuit board, labels, and visible repair work. A single blurry front photo is not enough evidence to authenticate an expensive vintage pedal. ### Op-Amps, Components, and RAT Myths The LM308 attracts more RAT mythology than almost any other component. Older RATs used it, while later production transitioned toward the OP07 family. JHS’s long-form RAT research argues that the later replacement is functionally equivalent in this circuit and supports that position with comparative electronic measurements rather than uncontrolled listening alone. That does not mean every RAT sounds numerically identical with every knob at twelve o’clock. Component tolerances matter. Pots vary. Clipping parts vary. Guitar output, power conditions, amplifiers, speakers, and small control adjustments all affect the final result. Buy an LM308-era RAT because you want that production period, construction, provenance, or collector value. Do not treat one chip as automatic proof that every later RAT is a compromised version. ### Used-Buying Checks A used RAT is simple enough that basic inspection tells you plenty. Check the footswitch for consistent engagement. Rotate each pot through its complete sweep and listen for dropouts, severe scratchiness, or dead sections. Test both audio jacks under light cable movement. Look closely at power. The supplied RAT instructions specify 9-volt operation, while the audio input and output use standard quarter-inch two-conductor connections. If an older pedal has unusual power hardware, confirm what was changed before connecting your normal board supply. Ask about modifications too. RAT pedals have been modified heavily for decades, so a vintage enclosure can hide changed clipping diodes, replaced components, altered pots, repaired traces, or power conversions. And verify authenticity when the price gets serious. ACT now maintains a RAT Certified Dealer program specifically while warning the community about counterfeit products. ## How to Dial In a RAT for the Rig You Already Have The best way to learn a RAT is to ignore internet clock positions for a few minutes. Set the amp where you actually use it. Match the RAT’s Volume close to your bypassed level, keep Distortion low enough to hear what it is adding, then move the Filter until the top end sits correctly. Change one control at a time. ### Low-Gain and Boost Settings Turn Distortion down first. Raise Volume until the pedal pushes the amp at the level you need, then open or close the Filter to suit the pickup and speaker combination. This end of the RAT range gets overlooked because the pedal has such a strong distortion reputation, yet the original manual itself starts its operating examples with a softer, tube-amp-like distortion setting. A clean amplifier makes the pedal’s own clipping character easier to hear. An amp that is already breaking up blends more of the RAT into the amplifier’s compression, so the useful Distortion setting often moves lower. ### Classic Distortion and Higher-Gain Settings Bring Distortion upward and the RAT stops behaving mainly like a push stage. Compression increases. Harmonics thicken. The attack gets more aggressive. Now the Filter becomes the stabilizer. If the sound gets brittle, turn Filter clockwise and remove more high-frequency energy. If the guitar disappears inside a dense mix, turn it counterclockwise and restore some edge. That control direction comes directly from the original operating instructions. The manual also treats heavy saturation as normal RAT territory, describing its final example as a sustain-heavy, heavy-gain sound. You do not need a separate fuzz switch to push the standard circuit into a thicker texture. ### RAT With Single-Coils, Humbuckers, Clean Amps, and Dirty Amps A RAT reacts to the rig feeding it. Brighter single-coils and brighter clean amps often make Filter adjustments more obvious because there is more upper-frequency content available to cut. Darker humbuckers or compressed amplifiers frequently tolerate a more open Filter position. Treat that as setup logic, not law. Pickup height, guitar volume, speaker response, amplifier EQ, and preamp gain can reverse the result quickly. The same goes for Distortion. A low-output guitar may benefit from more pedal gain. A hot humbucker feeding an already-pushed amplifier may have enough compression before the RAT adds much of its own. ### RAT and Tube Screamer Stacking A RAT and Tube Screamer overlap less than their reputations suggest. A Tube Screamer-style circuit is typically used for its mid-focused push and controlled low end. A RAT offers a broader distortion sweep and can generate much more of the final clipping character itself. Put the Tube Screamer first when you want to shape and tighten the signal before it reaches the RAT. Put the RAT first when you want the RAT to create the main distortion character, then use the Tube Screamer as the next gain and EQ stage. Neither order is universally correct. Decide which pedal should define the attack, then make the other support it. ## RAT-Style Alternatives: What Are You Trying to Change? A useful RAT alternative solves a specific problem. Cheaper. Smaller. More clipping modes. More EQ. Multiple historical voices. Different power options. Those are real differences. “Sounds like a RAT” alone is not a strong reason to replace the RAT 2 when the original still exists. ### Smaller or Less Expensive RAT-Style Pedals The Mooer Black Secret is a compact two-mode interpretation. Mooer specifies Vintage and Turbo modes, true bypass, 9V center-negative power, and a 42 mm-wide enclosure. Its Turbo mode provides more than twice the maximum output of Vintage mode. The TC Electronic Magus Pro takes another route, offering Classic, Turbo, and Fat modes. TC describes Turbo as an LED-clipping setting with greater headroom and output. Fat increases low-frequency weight and reshapes the upper mids, while Classic provides the base high-gain voice. These pedals make sense when footprint, mode count, or price structure matters more than owning an authentic ProCo enclosure. ### Switchable Clipping and Multi-Voice RAT Designs The Wampler Ratsbane keeps the recognizable Volume, Distortion, and Filter core, then adds Gain and Voice switches. Wampler’s three-position Gain switch changes the available gain structure, while Voice alters compression and clipping. The pedal accepts 9-18V DC power, with Wampler identifying 9V as its intended reference voltage. The JHS PackRat takes the multi-voice idea much further. JHS uses a switching network to route an analog signal through nine RAT-related circuit modes. Its published design uses 261 components and 40 individual switches to create those signal paths. That makes sense for someone who wants to compare different points in RAT history and several notable reinterpretations without owning a shelf of pedals. It is unnecessary complexity when the only goal is a dependable classic RAT sound. ### Boutique RAT Interpretations Boutique RAT pedals generally earn their extra complexity by changing clipping, control range, construction, historical coverage, or several of those at once. The Ratsbane adds gain and voice control. The PackRat adds multiple circuit architectures. The Sterling Vermin stays inside the official RAT family but uses a newer op-amp choice and selectable clipping arrangement. So compare the added feature to your actual problem. If you need a smaller board, solve size. If you want more headroom, solve headroom. If you want deeper low-frequency control, solve low end. If you want several RAT eras in one enclosure, solve that. Once you know what you are looking for, you can also compare current [used distortion pedals on Resyn](https://www.resyn.com/categories/distortion) without treating every RAT-style box as the same product. ## Is a RAT Pedal Right for You? The RAT makes the most sense when you want one gain pedal that covers substantial ground without a complicated interface. | If you want… | Start here | | --- | --- | | The standard RAT reference | RAT 2 | | The same basic job in less space | Lil’ RAT | | More headroom and a more open clipping response | Turbo RAT | | More saturation and compression | You Dirty RAT | | More low-end and clipping control | FAT RAT | | Two independent RAT channels and stackable voices | Deucetone RAT | | Expanded tone shaping | Solo | | A current boutique RAT with selectable clipping | Sterling Vermin | | A compact RAT-style pedal with multiple modes | Black Secret or Magus Pro | | Multiple historical and modified RAT voices | PackRat | | RAT foundation with extra Gain and Voice controls | Ratsbane | Do not buy the most complicated version because it has the longest feature list. The RAT 2 remains the cleanest starting point for most players because every other choice becomes easier once you know which part of the standard circuit you want changed. ## Frequently Asked Questions About RAT Pedals **What does a RAT pedal do?** It adds hard-clipping distortion across a broad gain range. Lower settings can work as dirty boost or overdrive, while higher settings produce the compressed, harmonically dense distortion associated with the RAT and eventually move toward fuzz-like saturation. **Is the RAT 2 distortion or fuzz?** It is a distortion pedal. Its high-gain behavior can become thick enough to overlap sonically with fuzz, which explains why both terms appear in RAT discussions. **Is the ProCo RAT the same as the RAT 2?** Not exactly. RAT describes the broader product family and historical circuit lineage. RAT 2 is the long-running standard version introduced in the late 1980s and remains the practical reference point for the family. **Which RAT models are currently made?** ACT’s current RAT category lists eight models: RAT 2, Lil’ RAT, Turbo RAT, You Dirty RAT, FAT RAT, Deucetone RAT, Solo, and Sterling Vermin. **How does a RAT compare with a Tube Screamer?** A Tube Screamer-style pedal is generally used for a more mid-focused push and controlled low end. The RAT covers a broader distortion range and can provide much more of the final clipping character by itself. **Can a RAT be used as a boost?** Yes. Keep Distortion low and raise Volume. The original operating instructions explicitly include softer, lower-gain use within the normal range of the pedal. **Can you date a RAT from its serial number?** Not reliably. ACT explicitly states that serial number alone is not an accurate dating method. Use enclosure style, graphics, controls, circuit details, and known production changes together. **How do you choose a RAT-style alternative?** Choose by the change you need. Size, clipping modes, EQ, headroom, low-frequency control, multiple historical voices, and price are more useful decision points than a generic “best clone” label. ##### The RAT 2 Is the Reference Point – The Right Variant Depends on What You Need Changed The RAT family makes more sense when you stop treating every version as a better-or-worse contest. Start with the RAT 2. Learn how Distortion, Filter, and Volume interact with your rig. Then move only when you can name the missing piece – more headroom, more compression, a smaller enclosure, deeper low-end control, multiple voices, or vintage provenance. That approach also makes used RAT shopping easier. You are buying a circuit and a specific revision for a reason, not paying extra because one component, sticker, or internet story has been declared magical. 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