There is a specific disappointment familiar to anyone who has bought an “amp-in-a-box” overdrive. You plug it in, you hear something in the right neighbourhood, and then you spend a fortnight discovering that it only does one thing. The knobs move, the sound barely does. It has a voice, and that voice is a single fixed point somewhere near the amp it claims to be.
The Catalinbread Formula No. 55 does not behave like that, and the reason is structural rather than magical. Catalinbread did not build a distortion circuit and then EQ it until it resembled a tweed Fender. They rebuilt the preamp of the 5E3 tweed Deluxe — part for part, in their own words — using an all-discrete JFET signal path, and then let the resulting circuit misbehave exactly as the original amplifier misbehaves.
Which means the knobs interact badly. The tone control loses influence as you turn the volume up. The low end tightens when you dig in and blooms when you back off. The thing sags. All of that is on purpose, because all of that is what a 5E3 does, and none of it is what a well-designed pedal does.
At $189.99 direct in 2026, this is one of the least fashionable and most quietly recommended overdrives in the boutique world. Here is what it actually is.
The Amplifier: Why the 5E3 Tweed Deluxe Is Worth Copying at All
The number in the pedal’s name is not decoration. The Fender 5E3 was the circuit revision of the tweed Deluxe that ran through the second half of the 1950s, and the “55” points squarely at that era. It is a deceptively humble design: a cathode-biased push-pull pair of 6V6 output valves making somewhere in the region of fifteen watts, a valve rectifier feeding the whole thing, a single twelve-inch speaker, and — critically — no negative feedback loop anywhere in the power section.
That last omission is the whole personality. Negative feedback is what makes a blackface Fender tight, clean and linear right up until it isn’t. Take it away and the amplifier becomes loose, harmonically rich, touch-reactive and gloriously easy to overdrive. Add a valve rectifier that cannot supply current fast enough for a hard pick attack and you get sag: the note ducks momentarily, then blooms out bigger than the initial hit. Guitarists have been chasing that compression-in-reverse feel ever since.
The 5E3’s control layout was equally strange. Two interactive volume controls that loaded each other down, one tone control whose authority collapsed as the volume climbed, and a usable clean range that ran out somewhere around four on the dial. Beyond that it was simply dirty, and the only way to clean it up was your right hand and your guitar’s volume knob.
Every one of those quirks made it into records. The tweed Deluxe is the amplifier behind an enormous amount of American electric guitar — most famously as the heart of Neil Young‘s live rig, where a late-fifties Deluxe has done duty for decades behind the wall of noise that Crazy Horse make; and, in the recording studio, on a very long list of sessions where players wanted a small amp that would break up at manageable volume. Larry Carlton, Billy Gibbons, Joe Walsh and Mike Campbell are all names that recur in tweed-Deluxe discussion, and the amp’s reputation as a session workhorse is why its market value has climbed so absurdly.
Which is the practical problem the Formula No. 55 exists to solve. An original 5E3 is now a collector’s item, it makes fifteen watts, it needs to be loud to be good, and it will require valve work. The pedal costs less than a set of replacement output valves for some vintage amps and fits between your tuner and your delay.
The Foundation Overdrive Series: Catalinbread’s Actual Thesis
The Formula No. 55 is not a standalone product. It belongs to Catalinbread’s Foundation Overdrive series, which is one of the more intellectually coherent product lines in the pedal industry, and the series concept is worth stating clearly because it explains the pedal’s odd behaviour.
Catalinbread’s premise is that most overdrive pedals are flavour — something you add to an existing amp sound. A Foundation Overdrive is meant to be the opposite: it replaces the front end of your amplifier entirely, so that your amp becomes little more than a power section and a speaker, and the pedal supplies the voice. Their instruction is blunt: use it and treat it exactly as you would the actual amplifier.
The series maps onto a shelf of classic amps, one pedal per circuit:
- Formula No. 5 — the original tweed-flavoured entry in the range, volume, tone and gain.
- Formula 51 — the 5F1 tweed Champ, and unusually it includes a power amp simulation and output transformer stage as well as a preamp.
- Formula No. 55 — the 5E3 tweed Deluxe. The subject of this article.
- Formula 5F6 — the late-fifties tweed Bassman, the amp that the first Marshalls were traced from.
- SFT — Ampeg-voiced, explicitly bridging the Rolling Stones’ Get Yer Ya-Ya’s Out sound and the modern stoner-rock use of the same amps.
- RAH — the three-knob tone circuit from the custom Hiwatt built for Jimmy Page, named for the Royal Albert Hall.
- Dirty Little Secret — the Marshall Super Lead and Super Bass tone circuits, reconstructed part for part.
Read that list and the Formula No. 55’s position becomes obvious: it is the smallest and most touch-sensitive voice in a range that otherwise trends toward big British stacks. It is the one you buy when you want the amp to get out of the way and let your hands do the work.
Catalinbread themselves have been building in Portland, Oregon since 2006, having started at Nic Harris’s kitchen table in Seattle in 2003. Harris was killed in a road accident in March 2016, aged 37; Kyle Sears and Brandon Rush bought the company in March 2020 and have kept the Foundation range in continuous production. Every pedal is hand-assembled one at a time, carries a three-year warranty, and — a small detail that tells you something about the culture — has a QA engineer’s initials written inside the enclosure.
Origins: A NAMM Debut and a Marketing Line Worth Quoting
The Formula No. 55 arrived on the back of a Winter NAMM show, with the pedal press picking it up in the opening weeks of 2017; the pedal blog Delicious Audio covered the launch demo on 8 February 2017, describing it as one of the dirt pedals that turned heads at the show.
Catalinbread’s own launch copy contained a phrase that has stuck to the pedal ever since, and it is genuinely the most useful single sentence written about it. They billed the 55 as a next-generation 5E3-inspired overdrive with “incredible range — from Grant Green to Crazy Horse!”
That is not marketing fluff, it is a specification. Grant Green’s tone is round, warm, articulate and essentially clean, sitting on the front edge of breakup with all the midrange left in. Crazy Horse is Neil Young with a tweed Deluxe pushed past the point of dignity, feeding back, sagging, snarling. Catalinbread are telling you that both of those live inside the same box, and that the journey between them is made with the Volume control and your picking hand rather than with a mode switch.
Nine years on the pedal is still in the catalogue, has been through a cosmetic redesign (the “new look” enclosure), and sits at $189.99 direct with free domestic shipping over $50.
Specifications
Two numbers in that table deserve a moment. The first is the current draw, which at roughly 5 mA at 9 V is among the lowest you will ever see on a pedalboard — an entire Foundation series could hang off one output of a small supply. The second is the “no internal controls” line. Catalinbread state it explicitly in the manual: open the pedal and there is nothing under the hood but a battery clip. That is a deliberate contrast with their own Echorec and Belle Epoch, both of which hide substantial functionality on trimpots. On the 55, what you see on the face is the entire pedal.
The Controls, and Why Two of Them Fight Each Other
Volume — this is the gain knob
The single most important thing to understand about the Formula No. 55 is that the knob marked Volume is not an output level control. It is the amplifier’s input volume, which on a 5E3 is the gain control. Catalinbread say so directly: it works in concert with the Hi/Lo switch to set your maximum available dirt, running from squeaky clean at the bottom to — in their own capitalised phrasing — DAMN THAT’S STANKY! at the top.
Because it is an amp volume, it also behaves like one. Turn it up and the pedal does not just get more distorted; it gets bigger, looser and more three-dimensional, and the note bloom on hard attacks becomes elastic. Roll your guitar’s volume back and the whole thing cleans up, because the circuit is genuinely responding to input level rather than clipping a fixed amount.
Tone — and the interaction that gives the game away
The Tone control is lifted from the 5E3 wholesale, and it inherits the amp’s most notorious quirk: as you wind the Volume control up, the Tone control’s influence becomes progressively more subtle, and at maximum Volume it does very little at all. This is not a fault. It is the actual behaviour of the actual tone stack, which is loaded differently as the preamp is driven.
It also tells you exactly where the Tone knob is useful: at lower Volume settings. Noon gives the flattest response. Below noon delivers what Catalinbread describe as smoky jazz cleans — dark, round, absolutely the Grant Green end of the advertised range. Above noon it opens into a barking, greasy upper-midrange that cuts through a band.
Presence — the modern addition
The real 5E3 has no presence control, and this is one of the two places where Catalinbread deviated from the original. Presence governs the 5 kHz region, and its stated purpose is practical rather than tonal ideology: it lets you match the pedal to whatever pickups and amplifier you happen to have. A bright single-coil into a blackface combo and a dark humbucker into a closed-back cab need different top ends, and without this control the pedal would only work properly with one of them.
Treat it as the “make this fit my rig” knob, set it once, and mostly leave it.
Master — the other deviation, and the one that makes it gig-usable
Master is the output level, and Catalinbread describe it as having “a heaping helping of output on tap.” That matters for two completely different use cases. Set the Volume low and the Master high and you get a huge, fat, woody clean tone at whatever level you need. Set both high and the pedal has enough output to push your amplifier’s own front end into overdrive on top of everything the 55 is already doing — the classic stacked-gain arrangement, but with an authentic tweed preamp doing the pushing instead of a Tube Screamer.
The Hi / Lo button — the valve-swap metaphor
The front-and-centre button switches between two discrete gain structures, and Catalinbread frame it as a preamp-valve swap rather than as a gain boost.
Lo (green) is the pedal behaving as though the amp were fitted with lower-gain 12AY7 preamp valves — historically correct for a fifties Fender, incidentally. It is cleaner overall, more immediate in the pick attack, and has noticeably more bounce when you are comping chords, while keeping the fat, juicy harmonic response that the design is built around.
Hi (red) is the hot-rodded 12AX7 mode: more gain, more saturation, and a different feel entirely. Catalinbread’s description of it is the best line in their manual — your pick “essentially turns into a throttle,” laying off the attack cleans it up, and there is always acceleration available when you lean into it.
The important practical note is that the two modes are not a clean channel and a dirty channel. They are two positions on one continuum, and they overlap. Catalinbread’s own advice is that Hi mode with the Volume at around 9 o’clock picks up roughly where Lo mode with the Volume maxed leaves off — which means the honest way to think about the pedal is as a single gain range from about zero to about eleven, with the button sitting in the middle of it.
Power: The Voltage Genuinely Changes the Instrument
Catalinbread are unusually specific about what different supply voltages do to this pedal, and this is one of the areas where their documentation is worth more than any review.
At 9 V the pedal has a slightly softer sound that saturates more easily. At 18 V you get more volume, more headroom and a more percussive attack. Their analogy is a good one: it is the difference between a 50-watt and a 100-watt amplifier. Their recommendation is explicit — 18 volts is great for playing with a band, where you want attack and clarity and enough level to cut through.
Then there is the trick nobody expects a manufacturer to print. Catalinbread suggest running the pedal from a battery drained down to as little as 3–4 volts for an even softer sound, and specifically recommend it for late-night playing when you do not want to wake anyone up. Deliberately starving a pedal is normally a modder’s stunt; here it is factory-endorsed and it is the closest thing the 55 has to a hidden third mode.
The connector is a standard centre-negative barrel, so it plays nicely with everything. Note that this is the opposite convention to some studio-oriented units — always check before you patch. Because the current draw is so low, isolation is rarely an issue, and a battery will last an extremely long time. Unplug the input jack to switch the battery off.
Famous Players: What We Could Verify, and What We Could Not
This is the section where most write-ups of this pedal quietly cheat, so we will not.
Catalinbread maintain a public artist page, and it is a genuinely impressive roster: Paul Gilbert, Eric Johnson, Ed O’Brien, Billy Corgan, Nels Cline, Sean Lennon, Noel Gallagher, Joe Perry, Richard Fortus, Wes Borland, Dan Auerbach, Carrie Brownstein, Andy Summers, Robin Finck, Isaac Brock, Phoebe Bridgers, Misha Mansoor and dozens more.
That list is brand-level, not model-level. It tells you those players have a relationship with Catalinbread. It tells you nothing whatsoever about which of the company’s thirty-odd pedals any individual actually uses, and treating a brand roster as a user list for one SKU is the single most common piece of dishonesty in gear writing. We are not doing it here.
Working from photographed evidence rather than rosters, the one name we can attach to the Formula No. 55 specifically is Brendan Ekstrom of Circa Survive, documented via a board photograph he posted himself with the caption “@catalinbread taking over the board.” Circa Survive also appear on Catalinbread’s own artist page, which corroborates the relationship at brand level. It is a photograph rather than a filmed rig rundown, so we grade it as good-but-not-gold-standard evidence and say so plainly.
What we could not verify: there is no Premier Guitar Rig Rundown we could locate that names the Formula No. 55 in body copy, and no manufacturer statement tying a specific named player to this specific model. Several retailer pages and aggregators imply celebrity usage by association with the brand roster; none of them survive a click-through. Our standing bar for a “famous players” claim in this series is a dated photographed board in a published rundown, a manufacturer page naming the player and the model, or a direct interview quote. Only the Ekstrom photograph gets anywhere near it.
The lineage, which is a different claim entirely
Here is the trap. Search for this pedal and you will find it sold on Neil Young, on Larry Carlton, on Billy Gibbons, on Keith Richards, on Danny Gatton, on John Fogerty, on Brian Setzer, on Eric Clapton. Every one of those associations is with tweed Fender amplifiers, not with a pedal that came out in 2017.
That distinction matters and it is not pedantry. The Formula No. 55’s claim on your money is that it reproduces the 5E3 circuit convincingly enough that the recorded history of the amplifier becomes a reasonable guide to what the pedal can do. That is a real and defensible claim. It is not the same as saying any of those players own one. Nobody in the paragraph above has been documented using this pedal, and the pedal is good enough not to need the borrowed glory.
Tone Recipes: Five Places to Start
1. The factory starting point — “Cleanish tweed”
Mode Lo/green · Presence noon · Tone noon · Volume noon · Master 10:00.
A mild, cleanish overdrive with an inherent low-mid fatness that survives any Tone setting. Push the Volume higher if you are running low-output pickups. Now roll your guitar volume back and listen to how completely it cleans up — that responsiveness is the thing you are actually buying.
2. Grant Green — the smoky jazz clean
Lo · Volume 9:00 · Tone 10:00 · Presence 10:00 · Master to taste.
Tone below noon, gain low, presence pulled back. Round, warm, articulate, right on the edge of breakup with all the midrange intact. Neck pickup, flatwounds if you have them. This is the pedal as a warm clean preamp, and it is arguably the most underrated thing it does.
3. Crazy Horse — Volume dimed
Lo · Volume maximum · Tone 1:00 · Presence noon · Master high.
Palm-mute a chord line here and listen to the grit and the low-end resonance that makes the cab sound like it is breathing. Then hit an open chord and let it ring — there is grind on the front of the note that resolves into fullness and clarity as it decays. Notice that the thump you heard when palm-muting disappears and the low end tightens when you play hard. That is the circuit doing what the amp does.
4. The throttle — Hi mode, medium gain
Hi/red · Volume noon · Tone noon · Presence 11:00 · Master to taste.
Fuller than anything Lo mode offers but still tight, with strong string definition when you dig in and full cleanup when you lay back. This is the setting to camp on if you want one sound for a whole gig and intend to steer it with your hands and your guitar’s volume knob.
5. Full send — Hi mode, Volume maxed
Hi/red · Volume maximum · Tone noon · Presence 11:00 · Master high.
The elastic sag on a hard attack that blooms out bigger than the initial hit. Brush the strings lightly and it is still dynamic; roll the guitar volume back and there are the tweed cleans again. Be warned that the Tone control has very little authority up here — that is the 5E3 tone stack behaving correctly, and the Presence knob becomes your main EQ.
A sixth, for the brave
A part-drained battery at 3–4 volts, Lo mode, Volume high. Soft, spongy, quiet and slightly broken. Factory-sanctioned, faintly ridiculous, and excellent at one in the morning.
Catalinbread’s own suggested starting point is worth following once before you do anything else, because it demonstrates the pedal’s central behaviour in about ninety seconds.
How It Compares
Against a Tube Screamer or any midrange-hump overdrive
A TS808 or SD-1 is a mid-boosting clipping circuit that shapes whatever amp it is pushed into. The Formula No. 55 is the opposite tool: it replaces the front end rather than seasoning it, and it has a fatter low-mid and a much wider dynamic swing. If your amp already has the voice you want, buy the screamer. If your amp is a neutral platform you are trying to give a personality to, buy the 55.
Against transparent overdrives
The Timmy, the King of Tone, the Greer Lightspeed, the Nobels ODR-1 and the EQD Plumes all aim, in different ways, to add gain without adding character. The 55 aims at the exact opposite. It is a character pedal in the most literal sense, and it will impose the tweed voice on everything downstream. There is no version of this pedal that is transparent, and buying it hoping for transparency is a category error.
Against a Klon
The Klon Centaur keeps your dry signal intact and blends gain alongside it; it is fundamentally an enhancement device. The 55 has no clean blend and no interest in preserving your existing sound. Different philosophies, and they stack well precisely because of that — 55 first for the voice, Klon-style boost after for level and sparkle.
Against digital amp modellers in a box
The closest direct rival is the UAFX Woodrow ’55, which models the same 5E3 tweed Deluxe digitally, complete with speaker and room simulation, stereo output and preset storage. The comparison is instructive rather than one-sided. The Woodrow gives you the whole amp and cabinet and is the better answer for direct recording or for silent practice. The Formula No. 55 gives you only the preamp, in analogue, with no latency and no menus, and expects a real amplifier to supply the rest. If you play through an amp, the Catalinbread is the more natural fit; if you play into an interface, the digital box wins. The same logic separates the Foundation series from the UAFX Lion ’68 and Ruby ’63.
Against an actual tweed amp
If you own a Mesa California Tweed or a genuine small Fender, the 55 becomes redundant as a voice and interesting as a second voice — a way of getting the tweed character out of a clean channel on a different amp, or a way of having tweed on a board built around a British-voiced head. That is also the argument for pairing it with a Plexi Drive Deluxe or the Marshall-voiced end of the Foundation range: two amps, one board, one footswitch each.
Buying Guide: Who This Is Actually For
Buy it if your amplifier is a clean platform with no personality of its own; if you play with your guitar’s volume knob constantly and want a circuit that rewards that; if you want a dirt sound built on low-mid fatness rather than a midrange spike; if you play blues, roots, Americana, indie, garage or heavy psych; or if you want a warm clean boost and an overdrive from the same enclosure.
Do not buy it if you want a transparent boost, if you need tight modern high gain, if you play through an amp that already has a strong voice you love, or if you are looking for a pedal that stays out of the way. It will not stay out of the way. It is a preamp with opinions.
Where it goes in the chain: early — right after your tuner and wah, before modulation and time-based effects. It is designed to see your pickups. Fuzz, if you use one, goes in front of it. Level-matching EQ such as a Boss GE-7 and clean boosts like the Keeley Katana or Xotic RC Booster go after it if you need a solo lift, because the 55’s own Master is already doing the heavy lifting on level. If you like a touch of extra sparkle and low-end firmness on top, an EP Booster after it is a well-worn combination.
New or used: the pedal has been in production continuously since 2017 and the only meaningful change has been cosmetic — the “new look” enclosure graphics. Circuit-wise, an early unit and a current one are the same pedal, so buy on condition and price rather than vintage. Used examples turn up regularly, which is less a comment on the pedal’s quality than on the fact that plenty of people buy amp-in-a-box overdrives expecting a transparent drive and are surprised.
Living With It
Three ownership notes that come up repeatedly.
Give it a week before you judge it. The Volume-and-Tone interaction is genuinely confusing on first contact, because pedals do not normally behave that way. Players who set it once, decide the Tone knob is broken and move on have simply not spent long enough at the low-Volume end where the Tone control does its work.
Set it at playing volume with the band. This is true of any amp-voiced pedal and doubly true of one built on a fifteen-watt cathode-biased circuit. Settings that sound rich and woody at bedroom level can turn muddy in a mix; the Presence control is what fixes that, and it needs to be set against the actual PA and the actual drummer.
Try 18 volts before you decide it lacks headroom. Catalinbread say the difference is substantial and they are not exaggerating. A lot of the complaints about the 55 being too loose or too soft are complaints about running it at 9 V through a small supply, in a band context where the manufacturer explicitly recommends the opposite.
Otherwise there is very little to maintain. No trimpots, no firmware, no batteries you need to think about given a 5 mA draw, and a three-year warranty from a company that answers email.
Frequently Asked Questions
Is the Formula No. 55 a distortion pedal or an amp emulator?
An amp emulator, specifically a preamp emulator. It reproduces the preamp section of the Fender 5E3 tweed Deluxe using an all-discrete JFET signal path, with the Volume and Tone controls replicated part for part from the amplifier. It is designed to replace your amp’s front end rather than to add a gain stage in front of it.
Why does the Tone knob stop working when I turn the Volume up?
Because that is exactly what the real amplifier does. The 5E3’s tone stack loses influence as the preamp is driven, and Catalinbread deliberately preserved that interaction. Use the Tone control at lower Volume settings, and use the Presence control as your main EQ when the Volume is high.
What is the difference between the Hi and Lo modes?
Lo (green) behaves as though the amp were fitted with lower-gain 12AY7 preamp valves: cleaner, more immediate attack, more bounce for chord work. Hi (red) is the hot-rodded 12AX7 equivalent: more gain and saturation, with your pick acting as a throttle. They overlap — Hi mode with the Volume around 9 o’clock is roughly where Lo mode with the Volume maxed leaves off.
Should I run it at 9 V or 18 V?
18 V for band use. Catalinbread’s own guidance is that 18 volts gives more volume, headroom and percussive attack — their analogy is a 50-watt amp versus a 100-watt amp — while 9 volts is softer and saturates more readily. Both are correct operation. The current draw is only around 5 mA at 9 V and 10 mA at 18 V, so power supply capacity is never the constraint.
Can I really run it from a nearly dead battery?
Yes, and the manufacturer suggests it. A battery drained to 3–4 volts produces an even softer, spongier sound that Catalinbread recommend for late-night playing at low volume. It will not damage the pedal. It is the closest thing the 55 has to a hidden mode.
Does it work in front of a valve amp or straight into a mixing desk?
In front of an amplifier. It emulates a preamp only — there is no power amp simulation, no output transformer stage and no speaker cabinet simulation, all of which are things you would need for a convincing direct sound. If you want the whole 5E3 including cab for direct recording, a digital modeller such as the UAFX Woodrow ’55 is the appropriate tool. Note that Catalinbread’s own Formula 51 does include a power amp simulator and output transformer stage; the 55 does not.
Which famous guitarists use the Formula No. 55?
Honestly: very few can be verified. Brendan Ekstrom of Circa Survive is documented with one via a board photograph he posted himself, and Circa Survive appear on Catalinbread’s artist roster. Catalinbread’s public artist page lists a great many other well-known players, but that page is brand-level and does not identify which pedals any individual uses. The famous names associated with the 5E3 tweed Deluxe amplifier — Neil Young, Larry Carlton, Billy Gibbons and others — used the amp, not this pedal, and we do not present them as users of it.
Where should it sit on my pedalboard?
Early in the chain, after tuner and wah, before modulation, delay and reverb. It is designed to receive your pickups directly, and its dynamic response depends on that. Fuzz goes before it. Boosts, EQ and time-based effects go after.
The Verdict Nobody Asked For
The Formula No. 55 is a pedal that is easy to dismiss for the wrong reason. It has four knobs and a button, it costs under two hundred dollars, it has no famous endorsements anyone can actually stand up, and it does not sound impressive in a shop for the first ninety seconds.
What it has instead is a design decision that almost nobody else makes: Catalinbread copied the amplifier’s faults along with its virtues. The tone control that gives up. The gain that only cleans up if you help it. The low end that rearranges itself depending on how hard you hit the strings. Those are the things that make a 5E3 addictive and they are precisely the things a sensible pedal designer would engineer out.
The payoff is a box with the widest usable dynamic range of anything in its price bracket, and a genuine claim on both ends of the range its maker advertised — the warm articulate clean at one end, the sagging tweed roar at the other, and your right hand as the only control that gets you between them.
If that is what you want, there is very little else like it. If it is not, no amount of knob-twiddling will turn it into a transparent overdrive, and you should buy something else with a clear conscience.