Some pedals arrive with a manifesto. The Xotic AC Booster arrived with a two-letter name and left the rest of us to fight about it for twenty years.
Ask around and you will get two confident answers to the same question. One camp says the AC stands for AC30 — that this is a Vox-chime-in-a-box, the pedal you put in front of a clean amp when you want that glassy, upper-mid clang without lugging a 70-pound combo to the gig. The other camp says AC means “almost clean” — a boost with a little hair on it, the sibling to the RC Booster’s transparency. Both explanations have been repeated in print for two decades. Neither appears anywhere in Xotic’s own manual, which describes the pedal in flatly unromantic language as “a natural sounding overdrive… not heavy distortion, but a sweet thick overdrive with an open non-compressed feel.”
That gap between what the pedal is called and what the manufacturer says it does turns out to be the most honest way into this box. Because when you actually open the AC Booster up — and people have, repeatedly, with degoop chemicals and a multimeter — what you find is not a Vox amplifier at all. It is something rather more interesting.
Van Nuys, California: Where the AC Booster Comes From
Xotic Effects is a brand of Prosound Communications, Inc., operating out of 14920 Calvert Street in Van Nuys, California — an address printed on the back of every Xotic manual, which is a pleasantly analogue detail for a company shipping worldwide. The same parent company handles Xotic guitars, Xotic basses, and the Raw Vintage line of pickups and hardware. Xotic’s own shop copy describes “nearly 20 years” as an innovator in sound and design, placing the company’s origin in the early 2000s.
The AC Booster is one of the original wave of Xotic pedals, most commonly dated to around 2002 and arriving alongside its cleaner sibling, the RC Booster. Dealer listings and pedal databases are not perfectly consistent on the exact year, and Xotic themselves have never made a point of celebrating an anniversary for it, so treat any single date you read — including this one — as approximate rather than gospel.
What is not approximate is the pedal’s staying power. The AC Booster stayed in the catalogue essentially unchanged for over two decades, an eternity in a market where boutique overdrives are launched, hyped and forgotten inside a single NAMM cycle. In 2025 Xotic finally revised it into the AC Booster V2, which we will come to. The original is still listed on Xotic’s website with its own product page and its own manual.
What Is Actually Inside the Box
In June 2020, Aion FX — a DIY PCB company that publishes rigorous reverse-engineering write-ups — traced three Xotic pedals directly: an AC Booster and a Bass RC Booster bought new in 2019, and a used RC Booster a couple of years old. The resulting tracing journal is the closest thing the guitar world has to a definitive AC Booster schematic, and it is worth reading their framing before the findings.
Xotic, Aion note, is “notorious” in the DIY scene — not for bad pedals, but for making reverse engineering difficult. Until relatively recently the company partially gooped its PCBs (potted them in opaque compound) and sanded the markings off its integrated circuits. On top of that, Xotic quietly revises its circuits, whether from ongoing tone-tweaking or component availability. The result was a decade of community traces that all disagreed slightly with each other, with no way to tell which differences were Xotic’s revisions and which were tracing errors.
Here is the headline finding, in Aion’s own blunt assessment of the range: these pedals are “little more than Tube Screamers and Bluesbreakers with a Baxandall tone stack, and they really do sound great.” That last clause matters as much as the first. Circuit ancestry is not a verdict on musical worth — the Klon Centaur is a boosted, buffered variation on well-trodden ground too, and nobody sane argues it does not work.
The AC and RC Share a Circuit Board
The single most useful fact about the AC Booster is one that Xotic has never advertised: the AC Booster and the RC Booster are built on the same PCB in the same production line. Aion confirmed this by degooping both and photographing them side by side. They are not two unrelated designs that happen to look similar. They are one platform, populated differently.
The difference is chiefly in the clipping section and the gain range. The RC Booster is voiced as the near-transparent, high-headroom boost with a little drive available. The AC Booster is the same architecture pushed further into overdrive territory, with a clipping arrangement that gives it the “sweet thick overdrive” the manual promises. Same skeleton, different muscles.
The Diode Arrangement — and the Revision Nobody Announced
The most technically distinctive thing Aion found in the AC Booster is the clipping diode layout: a seventh diode, D5, bridging the two pairs. Earlier community traces — and photographs of earlier AC Booster units — show a different configuration entirely: two diodes one way and one the other, an asymmetric arrangement much like a Boss-era OD-1. Aion’s conclusion is that the earlier traces were probably correct, and that Xotic simply changed the diode configuration at some point without telling anyone.
This matters if you are shopping used. Asymmetric clipping and the later bridged arrangement do not sound identical; they produce different harmonic content and different feel under the pick. If you have played a friend’s AC Booster and loved it, and then bought one online from a different era and found it slightly off, you are not imagining things.
The Gain Pot Got Bigger
Two further changes Aion documented in the 2019 unit versus earlier traces:
- The drive pot is 1M in the traced unit. Earlier versions used a 500kB pot, which means older AC Boosters simply have less maximum gain available. If you have read reviews describing the AC Booster as “basically a boost with a bit of grit” and other reviews describing it as “a genuine distortion pedal when cranked,” both reviewers may be right about different pedals.
- C6 changed from 100n to 47n, which raises the low-cut frequency of the clipping stage — meaning slightly less bass going into the dirt. A small change on paper, an audible one in a band mix, generally in the direction of tightness.
Aion also noted that the bypass switching is a bog-standard 3PDT true bypass arrangement, with some extra circuitry around the status LED — most likely to stop it popping when you engage the pedal, and irrelevant to the sound.
Specifications
Xotic publishes AC Booster specs in three places — the product page, the printed manual PDF, and the end-user shop listing — and they do not agree with each other. Rather than silently choosing one, here is the full picture, because the discrepancies are themselves useful information about the pedal’s long production life.
| Specification | Product page | Printed manual |
|---|---|---|
| Controls | Volume, Gain, Treble, Bass | |
| Boost available | 20 dB+ | |
| EQ range | Active two-band, ±15 dB | |
| Treble shelf | approx. 1.5 kHz – 10 kHz (manual graph) | |
| Bass shelf | approx. 90 Hz – 500 Hz (manual graph) | |
| Bypass | True bypass switching | |
| Dimensions (W/D/H) | 4.39″ x 2.38″ x 1.98″ (112 x 60 x 50 mm) | 110 x 60 x 50 mm |
| Weight | 0.6 lbs (280 g) | 0.6 lbs (270 g) |
| Current draw | 5 mA (shop listing says 6 mA) | 10 mA (max) |
| Power adapter | 9V–18V DC, negative tip, regulated recommended | 9V DC only, negative tip |
| DC jack | 2.1 x 5.5 mm, centre negative | |
| Battery | 9V (006P) x 1, approx. 40 hrs alkaline (manual) | |
| Input impedance | 500k ohm (min) | 1M ohm |
| Output impedance | 10k ohm | 2k ohm |
| Nominal input | −20 dB (manual) | |
| Battery access | Four screws, bottom plate | |
| Origin | Made in USA — Van Nuys, California | |
Three published current-draw figures for one pedal (5 mA, 6 mA and 10 mA max) is unusual even by boutique standards. For practical purposes it does not matter — any of those numbers is trivial for a modern isolated supply. The voltage discrepancy does matter, and we cover it in the ownership section below.
Famous Players — What Actually Checks Out
This is the section where gear articles usually go badly wrong, so let us be precise about what is verified and what is not. The AC Booster is a working musician’s utility pedal rather than a signature-sound icon, and its player list reflects that: fewer arena legends, more people who make their living on other people’s records.
Oz Noy — Confirmed
The strongest documented AC Booster user is the Israeli-born, New York-based fusion guitarist Oz Noy. Premier Guitar filmed his Rig Rundown in June 2014 at Nashville’s 3rd & Lindsley — a show where Brent Mason joined him to jam — and the published gear list is unambiguous: after a modded vintage Vox King wah and a Dunlop Octavio, Noy’s chain runs a Xotic RC Booster into a Xotic AC Booster, then into an Analog Man Brown Modded Ibanez TS808.
That ordering is instructive. Noy is not choosing between Xotic’s two boosts; he runs both, stacked, ahead of a Tube Screamer, into a custom Two-Rock Gain Master 100 built with old Fender transformers. Three gain stages of increasing colour in front of an amp that is already sweet. If you want a template for how the AC Booster is used at the professional level, that is it — not as the distortion, but as one layer in a graduated stack.
Adam Shoenfeld — Confirmed
Nashville session heavyweight Adam Shoenfeld — a player on hundreds of albums and 45 No. 1 country hits, starting with Jason Aldean’s “Hicktown” in 2005 — had an AC Booster on the XAct Tone Solutions board documented in his January 2022 Premier Guitar Rig Rundown. Its position is worth noting: the board’s buffer box has an effects insert placed specifically between the AC Booster and the MXR Dyna Comp, with a ZVEX Box of Rock ahead of it and an original Ibanez TS808 further down the chain.
Shoenfeld’s amps on that session were a Morgan SW-50, an early-’60s blonde Fender Bassman, a Dr. Z MAZ-38, a 1966 Vox Cambridge and a 1977 Marshall JMP combo. That is about as broad a tonal spread as a room can hold, and the AC Booster sat in front of all of it. Again: utility player, not one-trick pony.
Allen Hinds — Endorsed, With an Asterisk Worth Reading
Xotic’s own AC Booster product page carries a testimonial from session and fusion guitarist Allen Hinds, who says the pedal “feels responsive and expressive under my fingers and at the same time not too distorted or too buzzy,” calling that a rare combination. Hinds is a genuine long-term Xotic associate — the company builds an AH Booster signature pedal bearing his initials.
Here is where the series’ standing rule applies: the existence of a signature model is not evidence that the artist plays the non-signature pedal. Hinds’s endorsement quote is real and published by Xotic, so it counts as documented approval of the AC Booster. But if you are building a rig to chase his tone specifically, the pedal with his name on it is the AH Booster, not this one.
The Names You Will See Repeated — and Why We Are Not Repeating Them
Search “AC Booster famous users” and you will get a familiar aggregated roster: Neal Schon, Brad Paisley, Marcus Miller, Scott Henderson, Yannis Philippakis of Foals. These claims circulate through crowd-sourced gear databases and get copied outward from there. Some of them may well be true — a 2008 concert photo of a pedalboard is not nothing.
But a photo caption on an aggregator is not a primary source, and this series does not launder secondhand rosters into fact. None of those attributions could be confirmed against a manufacturer artist page, a filmed Rig Rundown, or a magazine interview at the time of writing. If you own an AC Booster because you read that Neal Schon used one, enjoy the pedal on its own considerable merits and hold the attribution loosely.
The Vox Question: Does It Actually Do AC30?
Since the name invites it, let us address the chime claim directly.
Premier Guitar, reviewing the V2 in May 2025, describes the AC Booster lineage as “a classic Vox-boost-in-a-box pedal” and reports that with the high-mids juiced and treble nudged you are “squarely in clanging Top Boost territory.” So the association is not invented by forum posters; it is how the guitar press hears the pedal too.
But note what that sentence actually says. The Top Boost impression arrives when you deliberately EQ toward it — treble up, upper mids emphasised. The AC Booster’s active two-band Baxandall EQ is powerful enough (±15 dB, with the treble shelf running from about 1.5 kHz up to 10 kHz) to build a convincing chime out of a fairly neutral overdrive. That is a credit to the tone stack, not proof that the circuit is modelling a Vox AC30.
Genuine AC30 tone — the sound Brian May, The Edge and Rory Gallagher built careers on — is a whole-amplifier phenomenon: EL84 power-section compression, cathode bias sag, an alnico speaker’s response, the specific interaction of a Top Boost tone stack with a hot preamp. No four-knob overdrive in front of a solid-state clean channel is going to reproduce that. What the AC Booster will do is push a good tube amp into a bright, mid-forward, harmonically busy overdrive that lives in the same postcode. For most gigs, that is the useful outcome anyway.
Tone Recipes and Settings
The Always-On (Xotic’s own suggested use)
Volume 1 o’clock, Gain 8 o’clock, Treble noon, Bass noon. Xotic’s marketing explicitly notes that many players simply leave the AC Booster on at all times, and this is the setting for it. Almost no added dirt, a modest level lift, and the pedal’s output buffer tightening up a long cable run. Set the volume so that engaging and bypassing produces no obvious jump — you want thickening, not loudness.
Chime Machine (the Top Boost approximation)
Volume 11 o’clock, Gain 10 o’clock, Treble 2 o’clock, Bass 10 o’clock. This is the settings equivalent of what Premier Guitar described. Trebles up, bass pulled back to stop the low end getting woolly as the gain rises, gain low enough that the pedal stays glassy rather than fuzzy. Best on a bridge single-coil into an amp with genuine top-end headroom. Add a touch of spring reverb and it will jangle convincingly.
Blues Push
Volume noon, Gain 1 o’clock, Treble 11 o’clock, Bass 1 o’clock. The AC Booster’s “open, non-compressed” character is its main advantage over a Screamer here — it does not squash your dynamics, so picking harder genuinely gets you more dirt. Roll your guitar volume back to 7 and it cleans up nearly all the way.
Full Distortion (what the 1M pot bought you)
Volume 10 o’clock, Gain maxed, Treble 1 o’clock, Bass 11 o’clock. Xotic’s own copy says the wide-range gain control provides “enough gain for it to work as a distortion pedal when turned all the way up,” and on a later unit with the 1M pot that is fair. Pull the bass back — the clipping stage gets flabby with too much low end feeding it, which is presumably why Xotic changed C6 in the first place.
Stacking, Oz Noy Style
AC Booster: Volume noon, Gain 9 o’clock, Treble 12:30, Bass noon — placed before a Tube Screamer. Set the AC as a colouring boost rather than the primary dirt, then let the TS808 or TS9 behind it do the midrange compression. The AC’s EQ then functions as a pre-emphasis control for the Screamer, which is a far more flexible arrangement than either pedal alone.
Tightening a High-Gain Amp
Volume 2 o’clock, Gain off/minimum, Treble 1 o’clock, Bass 9 o’clock. The classic boost-into-saturated-amp move, but with a real EQ attached instead of a fixed mid hump. Cutting bass before the amp’s preamp is what produces the tightness; the treble boost restores pick attack that heavy gain smears.
All settings assume clock positions with the pedal into a clean or edge-of-breakup tube amp. The Treble and Bass controls are active and centre-detented in feel around noon — noon is flat, and everything above or below is genuine boost or cut, not the passive roll-off you get on a Tube Screamer tone knob. Move them in small increments; ±15 dB is a lot of EQ.
How It Compares
AC Booster vs RC Booster
Same PCB, different voicing. The RC is the cleaner, more headroom-focused of the pair — the one you buy if the phrase “transparent boost” appeals. The AC is the one you buy if you want the boost to do something tonally. If you only own one Xotic pedal and you play mostly clean with occasional grit, take the RC. If your amp is already at the edge and you want to push it over with character, take the AC.
AC Booster vs BB Preamp
The Xotic BB Preamp is the most gained-up and most compressed of the Xotic drive family, and — per Aion’s separate trace of it — the most explicitly Tube Screamer-derived, with a hard-wired TS tone stack and two extra op-amp stages grafted in. It has more level on tap (30 dB+ against the AC’s 20 dB+) and a pronounced Screamer midrange. The AC Booster is looser, more open, less obviously voiced. Players who find the BB too “honky” usually end up on the AC.
AC Booster vs EP Booster
Different jobs entirely. The Xotic EP Booster is a two-knob, one-trick Echoplex preamp emulation in a mini enclosure — glorious at what it does, with no EQ to speak of beyond an internal DIP bright switch. The AC Booster is a four-knob tone-shaping tool. Many boards, sensibly, carry both.
AC Booster vs Tube Screamer
The Screamer’s defining feature is its midrange bump and bass roll-off, which is exactly why it sits so well in front of a Marshall and exactly why some players find it nasal on its own. The AC Booster gives you a flatter starting point plus the ability to build a mid hump — or not — using the two-band EQ. Less iconic, considerably more flexible. If you want the hand-wired Screamer experience, the TS808HW is the other end of that argument.
AC Booster vs OCD, Timmy and ODR-1
The Fulltone OCD is louder, more aggressive and more amp-like at high gain — a different animal, closer to a small Marshall than a Vox. The Timmy is the AC Booster’s closest philosophical rival: a low-gain, EQ-equipped, deliberately uncoloured drive, though the Timmy’s controls are passive cut-only where the Xotic’s are active boost/cut. The Nobels ODR-1 occupies similar Nashville-session territory to the AC Booster and costs a fraction as much, with a single Spectrum control instead of two bands.
The AC Booster V2 (2025)
In May 2025 Premier Guitar reviewed the AC Booster V2, scoring it 4.1 at a $180 street price. Xotic’s redesign keeps the four main knobs and adds:
- A second, footswitchable boost circuit, controlled by a small clear knob sitting in the centre of the four-knob array
- Four DIP switches on the right-hand side of the enclosure, engaging compression, modern-or-classic voicing, low-mid boost and high-mid boost
- All of it inside the same compact enclosure footprint
The reviewer’s verdict was positive — the classic Vox sounds are intact, the modern voicing “trades some furry mid-range chunk for a bit more aggression and clarity,” the compression is useful for levelling leads, and the separate high-mid and low-mid switches were singled out as more musically precise than a conventional single mids knob. The one complaint: the boost knob is genuinely awkward to reach, wedged as it is between the four main controls.
Note the design logic here. The V2 does not replace the original’s voice; it packages the tweaks people were already making — a bit of compression, a mid emphasis, a level jump for solos — into switchable form. If your reason for wanting an AC Booster is “one warm overdrive that stays out of the way,” the original does that at, frequently, a lower used price.
Buying Guide
New: Xotic still lists the original AC Booster on its own website with a live product page, manual and shop listing, alongside the V2. Dealer availability of the original varies as the V2 takes over shelf space. The V2’s $180 street price is the reference point for what a current Xotic four-knob drive costs.
Used: This is where the AC Booster gets interesting, and where the circuit revisions matter. Given what Aion documented, a used AC Booster could be:
- An early unit with a 500kB gain pot, asymmetric OD-1-style clipping and a 100n C6 — less maximum gain, a bit more low end into the clipping stage, a slightly different distortion character
- A later unit (the 2019 trace) with a 1M gain pot, the bridged D5 diode arrangement and a 47n C6 — more gain on tap, tighter low end
- Something in between, since Xotic revised quietly and without announcement
None of these is “the bad one.” But if you are buying unheard on the strength of a demo video, understand that the video may not be of the same circuit. Ask the seller for photos of the enclosure and, if possible, the serial number, and ask what year they bought it. Xotic’s customer service has historically been willing to answer serial-number questions by email.
What to check on any used unit: the four bottom screws (stripped heads suggest repeated battery changes and possibly amateur poking around inside), the DC jack for wobble, the footswitch for reliable engagement, and the pots for scratchiness. The enclosures are robust and the build is USA-made, so cosmetically rough units are usually electrically fine.
Ownership Notes
The 9V vs 18V Contradiction — Read This Before You Plug In
Xotic’s product page states the optional AC adapter range as 9V–18V DC. Xotic’s printed manual for the same pedal states 9V DC, full stop. Both documents are published by the manufacturer and both are currently live.
The most plausible reading is that the manual reflects the original specification and the product page reflects later production, since Xotic actively sells a Voltage Doubler accessory — a step-up converter taking 9V to 15V or 18V, rated to 80 mA maximum — and explicitly markets higher voltage into its pedals for “more headroom… more dynamic, more headroom, top end and brightness, less compressed sound.”
Practical advice: if you have an older AC Booster, run it at 9V. The risk of feeding 18V into a circuit specified for 9V is not worth the extra headroom. If you have a recent unit and want to experiment, Xotic’s own doubler is the sanctioned route. And note that “more headroom” is not automatically “better” — part of the AC Booster’s appeal is a slight compression that goes away at higher voltage.
Power and Battery
Standard 2.1 x 5.5 mm centre-negative jack, compatible with Boss PSA, 1-Spot, Voodoo Lab and similar supplies. The manual quotes roughly 40 hours of continuous use from an alkaline 9V. The battery lives under a bottom plate secured by four screws — no tool-free hatch — so if you gig regularly, use a power supply and stop unscrewing things in the dark. As with most true-bypass pedals, the input jack acts as the battery switch, so unplug your cable when the pedal is not in use or the battery drains.
Buffering and Board Placement
The AC Booster is true bypass, meaning it contributes nothing to your signal when it is off — including no buffering. A board full of true-bypass pedals plus long cable runs will lose high end, so put a buffer somewhere. Adam Shoenfeld’s professionally built board solves this with a dedicated always-on XTS buffer box; a cheaper solution is one buffered pedal (a Boss unit, a tuner) at the front.
Placement-wise, the AC Booster works in the traditional drive position — after wah and compression, before modulation and time-based effects. If you are stacking, the general rule holds: lower-gain and more transparent first, higher-gain and more coloured after, which is exactly why Noy runs RC into AC into Screamer rather than the reverse.
Frequently Asked Questions
What does “AC” actually stand for?
Xotic has never definitively said in its published product documentation. The two circulating explanations are “AC30,” referencing the Vox amplifier, and “almost clean,” positioning it relative to the RC Booster. The manual itself describes only “a natural sounding overdrive,” with no mention of Vox. Treat any confident answer you read — including on this page — as an interpretation rather than a manufacturer statement.
Is the AC Booster a Vox AC30 emulator?
Not as a circuit. It is a Tube Screamer/Bluesbreaker-lineage overdrive with a Baxandall two-band active EQ, per Aion FX’s direct trace. What it can do is EQ toward a chimey, upper-mid-forward voice that Premier Guitar called “clanging Top Boost territory.” That is a tone-stack achievement, not amplifier modelling.
Is the AC Booster the same as the RC Booster?
Same circuit board, different component population. The RC is cleaner and more transparent with more headroom; the AC has more gain and more clipping colour. Aion FX degooped and photographed both side by side to confirm the shared platform.
Can I run the AC Booster at 18V?
The product page says 9V–18V; the manual says 9V only. If your unit is older, stay at 9V. If it is recent and you want the extra headroom, use Xotic’s own Voltage Doubler, which is designed for exactly this. Verify against the documentation that shipped with your specific pedal rather than the generic figure.
Is it true bypass?
Yes — Xotic states true bypass switching on the product page and in the manual, and Aion FX confirmed a standard 3PDT arrangement in the traced unit. Because of that, the pedal provides no buffering when disengaged, so plan your board accordingly.
Does it work for metal or high-gain playing?
Not as a standalone metal distortion — even maxed, this is an overdrive rather than a saturated high-gain circuit. As a boost in front of an already-saturated amp it is excellent, and the active EQ lets you cut bass before the preamp for tightness in a way a fixed-voiced Screamer cannot.
Why do different AC Boosters sound different?
Because they are different circuits. Xotic revised the clipping diode arrangement, changed the gain pot from 500kB to 1M, and altered C6 from 100n to 47n at various unannounced points over the pedal’s twenty-plus-year run. Aion FX’s tracing journal documents all three changes. Two AC Boosters from different eras are cousins, not twins.
Should I buy the original or the V2?
Buy the V2 if you want the extra features — the footswitchable second boost, the compression switch, the modern voicing option, and the separate low-mid and high-mid boosts — and can live with a fiddly centre boost knob. Buy the original used if you want the classic voice at a lower price and do not need the switching. The V2 does not sound “better”; it does more.
How does the AC Booster compare to the BB Preamp?
The BB Preamp has more gain (30 dB+ versus 20 dB+), noticeably more compression, and a pronounced Tube Screamer-derived midrange from its hard-wired TS tone stack. The AC Booster is more open, less compressed and more neutral before you start moving the EQ. Players who find the BB too midrange-heavy generally prefer the AC.