The Boss XS-1 Poly Shifter is a compact polyphonic pitch shifter pedal from Boss, released in October 2025 alongside the larger Boss XS-100. It instantly changes the pitch of a guitar, bass, or other instrument across a range of plus or minus seven semitones or plus or minus three octaves, using new Boss pitch-shifting algorithms running on a specially selected DSP platform123.
Boss positions it as instant retuning in a convenient, compact footprint: a metal player can drop into a lower tuning mid-set without touching the machine heads, or a player can blend shifted and direct sound for 12-string style effects and parallel guitar and bass sounds14. It launched at $199.99 in the United States5.
A compact polyphonic pitch shifter
Pitch shifting moves every note you play up or down by a set interval, and polyphonic shifting means full chords track cleanly rather than glitching the way older monophonic shifters did. Guitar Pedal X reported that Boss spent over two years developing the XS series toward "a more pristine clear and precise glitch-free style of" shifting7, and Delicious Audio described the XS-1 as offering "glitch-free, ultra-fast tracking across a wide range of up to ±7 semitones or ±3 octaves"3.
The XS-1 covers three main jobs:
- Alternate tunings: shift down (or up) by up to seven semitones for drop and lowered tunings without retuning the instrument1.
- Octave shifts: shift up to three octaves, and blend the direct sound back in with the Balance knob for 12-string effects, parallel guitar/bass sounds, and other layered textures1.
- Detune mode: a Detune mode creates doubling effects with high-definition tone85.
Boss says the XS-1 provides "balanced polyphonic performance that feels natural and musical across all playing styles, pickup positions, and pedal setups"1. It is a digital pedal, powered by finely tuned algorithms on its DSP platform1.
The controls: Balance knob, pedal switch and CTL/EXP jack
The XS-1 keeps its panel to a two-knob interface9, with the main sound shaping done by a single Balance knob and the pedal switch.
| Control | What it does |
|---|---|
| Balance knob | Adjusts the mix between the shifted effect and your direct sound1 |
| Pedal switch | Turns the effect on and off; assignable for standard toggle or momentary operation108 |
| CTL/EXP jack | Accepts a footswitch for instant preset recall, or an expression pedal for real-time pitch sweeping3 |
Boss gives specific guidance on the Balance knob. With semitone tunings, you usually want it set for effect only, so the unshifted direct signal does not clash with the shifted pitch. For octave shifts, blending in the direct sound is the point: that is where 12-string effects and parallel guitar/bass sounds come from1.
The pedal switch mode is set with the flip of a panel control: toggle for standard on/off use, or momentary for pitch shifts that only last while you hold the switch down11. Up to two external footswitches can be connected for fast access to alternate tuning modes with your preferred Balance settings10.
An expression pedal in the CTL/EXP jack gives linear pitch control, effectively turning the XS-1 into a whammy-style sweep pedal1. In a Guitar World interview on the XS series, Boss's Matt Knight noted that "if you wanted to use XS-1 as an expression device, you could"12.
Power and connections
Guitar World's review lists the power requirement as a 9V AC supply drawing 160 mA, not included with the pedal2. RockBoard's PedalPedia entry for the XS-1 instead lists 9V DC, center negative13. There is a 9V battery compartment hidden under the footswitch2, and the listed weight of 410g (0.9 lbs) includes a battery2.
The pedal measures 73mm wide, 129mm deep and 59mm high2, standard Boss compact dimensions, and carries a Boss five-year warranty1. Output is a single TS output7.
The 160 mA current draw is high for a compact pedal, well above a typical analog overdrive. Players running isolated supplies should check their unit's per-output budget, and the supply is not included in the box2.
How it differs from the XS-100
The XS-1 launched alongside the Boss XS-100, its larger sibling at $349.995. Pedal of the Day calls the XS-100 the big brother, "one that expands on the features and productivity of its smaller counterpart"14. The core difference is control and range:
| XS-1 | XS-100 | |
|---|---|---|
| Shift range | ±7 semitones or ±3 octaves1 | Onboard pedal with linear pitch control across ±4 octaves1119 |
| Expression control | CTL/EXP jack for footswitch or expression pedal3 | Onboard pedal with integrated toe switch, plus up to two external footswitches or an expression pedal317 |
| MIDI | Not MIDI compatible15 | Not stated in the same terms; the XS-100's support pages cover extended control215 |
| Launch price | $199.995 | $349.995 |
Guitar World's review notes the XS-1 carries the same shifting capabilities as the XS-100, "albeit with a reduced +/- three-octave total range"2. The XS-100's onboard rocker pedal gives continuous pitch sweeps from the unit itself, where the XS-1 needs an external expression pedal for the same kind of control.
Reviewers have compared the two directly. Guitar.com's Richard Purvis wrote:
"The XS-100 is a chunk of fun for sure, but I like the XS-1 a lot more. It's got all the features you need, compatible e"16
finding the XS-1 far cheaper, easier to use and much smaller than the XS-10016. Guitar World's Phil Barker found the detuning "incredibly convincing, and with more typical usages, the tra[cking is faultless]"2.
Where it came from
Boss announced the XS-1 and XS-100 on 25 September 2025, its first new pitch devices since the PS-6 Harmonist era, with both pedals available in October 202551217. The XS series algorithms were developed over roughly two years7. Boss's own article on the series, by Rod Brakes with Hideyuki Mamori, frames the XS-1 around practical retuning: "a metal guitarist could use the XS-1 to instantly drop into a lower tuning and perform grinding, heavily saturated low-e[nd riffs]"4.
The XS-1 sits in Boss's pitch and octave range alongside the XS-100, the PS-6 Harmonist and the OC-5 Octave17. Guitar Pedal X measured its latency at 13 to 14 ms in 202618.
Videos
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Pedalboards of Doom and Jason Wharton
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Questions
Does the Boss XS-1 take a battery?
Yes. There is a 9V battery compartment hidden under the footswitch, and the pedal's listed weight of 410g includes a battery. A power supply is not included with the pedal, so players who want to run it from a supply need to add one.
Does the Boss XS-1 have MIDI?
No. The XS-1 is not MIDI compatible and cannot be slaved to MIDI control. Players who need MIDI integration would have to look at the larger XS-100 Poly Shifter instead, which sits above it in Boss's pitch-shifting range.
Can you use an expression pedal with the XS-1?
Yes. The CTL/EXP jack accepts an expression pedal for linear pitch control and real-time pitch sweeping, or a footswitch for instant preset recall. Up to two external footswitches can be connected for fast access to alternate tuning modes with preferred Balance settings.
What is the latency of the Boss XS-1?
Guitar Pedal X measured the XS-1 at 13 to 14 ms. That figure was reported in 2026 in the context of comparing pitch-shifting pedals, and it is the only published measurement of the pedal's latency in the sources covering it.
Is the Boss XS-1 good for bass?
Yes. Boss states the XS-1 can instantly change the pitch of a guitar, bass, or other instrument, and describes its polyphonic performance as natural and musical across all playing styles, pickup positions and pedal setups. Blending the direct sound with an octave down also creates parallel guitar and bass style sounds.
Is the XS-1 true bypass?
No. Guitar World's review lists the bypass as buffered. Like most Boss compact pedals it uses a buffer in bypass rather than a true bypass switching arrangement.
Sources (18)
- BOSS - XS-1 | Poly Shifter, BOSS (boss.info)
- Boss XS-1 Poly Shifter review, Guitar World, 2025-10-29
- BOSS Poly Shifter XS-1, Delicious Audio, 2025-10-31
- Flawless Feel, Sublime Sound, Perfect Precision: The XS Series Poly Shifters, BOSS (articles.boss.info), 2025-12-18
- BOSS Introduces Two Pitchshifting Pedals, Sonic State, 2025-09-25
- BOSS - XS Series Pitch Pedals, BOSS (boss.info)
- Guitar Pedal X, Guitar Pedal X, 2025-09-25
- BOSS - XS-1 | Poly Shifter, BOSS (boss.info)
- The 5 Best Pitch Shifter Pedals for Wild Sounds and Perfect Tracking, gearnews.com, 2026-03-16
- BOSS - XS-1 | Poly Shifter, BOSS (boss.info)
- BOSS - XS-1 | Poly Shifter, BOSS (boss.info)
- How the Boss XS-1 and XS-100 reimagined the pitch-shifter, Guitar World, 2026-01-29
- XS-1 Poly Shifter by BOSS, RockBoard PedalPedia, 2026
- Boss XS-100 Poly Shifter Octave Pitch-Shifter, Pedal of the Day, 2026-03-17
- Boss XS-100 & XS-1 Poly Shifter takes on DigiTech Whammy, Guitar World, 2025-09-25
- Boss XS-1 Poly Shifter review, guitar.com, 2025-12-31
- BOSS - XS-1 | Poly Shifter, BOSS (boss.info)
- Guitar Pedal X, Guitar Pedal X, 2026-06-18
