Boss - EX-4 Effects Expander
Take your creative vision to the next level with the EX-4, an innovative BOSS effects unit that expands the range of your pedalboard—without changing what already works. This compact inspiration machine complements your current setup with new sound-shaping options and real-time performance tools, encouraging you to explore fresh textures with the rig you already love.
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The Nantel Verdict
The Nantel Verdict
Compact effects expander with 6 simultaneous effects; integrates via MIDI or analog control into existing BOSS ecosystems; real-time knob editing and expression pedal support; deep algorithmic reverbs and delays alongside modulation effects.
Requires pedalboard space (compact footprint); benefits from expression pedal integration; MIDI connectivity recommended for full workflow potential. Works best with BOSS gear or compatible controllers via standard protocols.
The EX-4 respects what's already working while opening unexplored sonic territory. Essential for players committed to their current setup but hungry for refined textures and performance depth.
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A New Dimension to Your Board
Take your creative vision to the next level with the EX-4, an innovative BOSS effects unit that expands the range of your pedalboard—without changing what already works. This compact inspiration machine complements your current setup with new sound-shaping options and real-time performance tools, encouraging you to explore fresh textures with the rig you already love.
Highlights
- Compact effects processor that expands the capabilities of any pedalboard
- 120 premium BOSS effects, including overdrives/distortions, mod effects, delays, reverbs, and more
- Run up to four effects at once, including multiple instances of the same effect
- Dedicated utility blocks, including foot volume, two noise suppressors, send/return, and divider/mixer
- Fluid operation with an informative color display, intuitive knobs, and dedicated FX buttons
- Independent global EQ for overall sound shaping
- Gear Suite feature allows you to quickly configure each effect with the turn of a knob
- Control effects using dual multi-function footswitches with color LEDs
- Versatile mono/stereo I/O, flexible effect loop, and space-saving TRS MIDI jacks
- Manual and Memory modes for stompbox-style or preset-based effect control
- 128 preset memories for guitar and bass, plus 128 user memories for saving custom sounds
- Create complex effect configurations with advanced series, parallel, and wet/dry options
- Use the effect loop to build reorderable chains with external pedals
- Seamless memory changes with full carryover of delay and reverb effects possible with certain effect configurations
- Use the footswitches for basic effect and preset control, or access deeper assignment features for sophisticated custom operation
Expanded Range, Minimal Size
Modern players carefully curate their pedalboard builds, and every slot must earn its place. The EX-4 more than carries its weight, delivering a vast library of historic BOSS effects in a modest footprint. It’s the ideal utility pedal for musicians who love to experiment with effects, and an essential tool for stage players who cover many songs/styles and studio musicians who need to build professional sounds when the clock is ticking.
Your Creative Launchpad
With up to four simultaneous effects and flexible connectivity to integrate with everything on your board, the EX-4 has what you need to elevate your core sound with a universe of tonal possibilities. The interface is designed for immediate results, providing a fluid platform to dial up inspiring tones without endless tweaking.
Effects to the Max
Every major category is available among the 120 effect selections in the EX-4, including overdrive and distortion, modulation, delay, and reverb, as well as bass-tuned effects and unique BOSS favorites like Slow Gear and Slicer. You also get foot volume and other dedicated utility blocks that can be placed anywhere within an effect chain, plus a global EQ for overall sound shaping.
Build Sounds Fast with Gear Suite
The EX-4’s Gear Suite feature enables lightning-fast tone creation with ready-to-go sounds. Each effect type has multiple Gear Suite settings with professionally tuned parameters, all available with the turn of a knob. Better still, you can edit effect parameters and save your favorites for instant access to custom settings for every effect.
Free-Flowing Interface
A 2.4-inch color display gives you a clear, inviting view of the full signal chain, individual effect blocks, editing options, menus, and more. With dedicated FX buttons, you can turn effect blocks on/off with a single press and access editing parameters with a long press. Button colors dynamically change to match the display's effect colors, making navigation frustration-free.
Dual Footswitches with Split LEDs
Rugged dual-function footswitches can be custom-configured to suit your performance needs, with assignments that include effect block on/off, memory up/down, master bypass, tap tempo, individual parameter control, and more. A newly designed color LED system surrounds the footswitches, making it easy to identify the current footswitch functions as you perform.
Connect and Create
Four audio jacks support mono or stereo connectivity, with the option to use two jacks as an effect loop to place external pedals anywhere in the EX-4's effect chain for complex sound configurations. Two footswitches or an expression pedal can be connected for more real-time control, while space-saving TRS MIDI I/O unlocks deep integration with other MIDI pedals, switching systems, and external clocking devices.
Specifications |
|
| Sampling Frequency | 48 kHz |
| AD Conversion | 24 bits + AF method |
| *AF method (Adaptive Focus method) This is a proprietary method from Roland & BOSS that vastly improves the signal-to-noise (SN) ratio of the AD and DA converters. | |
| DA Conversion | 32 bits |
| Processing | 32-bit floating point |
| Effects | 120 types |
| Maximum Number of Effects | 4(FX1-4) + 6(DIVIDER+MIXER, SEND RETURN, FOOT VOLUME, NOISE SUPPRESSOR1, NOISE SUPPRESSOR2, GLOBAL EQ) |
| Memories | 128 (User) + 128 (Preset) |
| Nominal Input Level | INPUT L/MONO jack, INPUT R(RETURN) jack: -10 dBu |
| Maximum Input Level | INPUT L/MONO jack, INPUT R(RETURN) jack: +7 dBu |
| Input Impedance | INPUT L/MONO jack, INPUT R(RETURN) jack: 1 M ohm |
| Nominal Output Level | OUTPUT L/MONO jack, OUTPUT R(SEND) jack: -10 dBu |
| Output Impedance | OUTPUT L/MONO jack, OUTPUT R(SEND) jack: 1 k ohm |
| Recommended Load Impedance | OUTPUT L/MONO jack, OUTPUT R(SEND) jack: 10 k ohms or greater |
| Controls | DOWN/1 switch, UP/2 switch, |
| MENU/EXIT button, GEAR SUITE button, FX1 button, FX2 button, FX3 button, FX4 button, | |
| SELECT knob, TYPE/VALUE knob, 1-3 knobs | |
| Display | Color Graphic LCD (320 x 240 dots) |
| Connectors | INPUT L/MONO jack, INPUT R(RETURN) jack, OUTPUT L/MONO jack, OUTPUT R(SEND) jack, : 1/4-inch phone type |
| MIDI IN jack, MIDI OUT jack : Miniature phone type | |
| CTL1([3]),2([4])/EXP jack: 1/4-inch TRS phone type | |
| USB port: USB Type-C(R) | |
| DC IN jack | |
| Power Supply | AC adaptor (PSA-S series) |
| Current Draw | 300 mA |
| Accessories | STARTUP GUIDE |
| Leaflet "Read Me First" | |
| AC adaptor: PSA-S series | |
| Rubber foot x 4 | |
| Options (sold separately) | Footswitch: FS-5U, FS-5L, FS-6, FS-7 |
| Expression Pedal: FV-500L, FV-500H, EV-30, Roland EV-5 | |
| TRS/MIDI connecting cable: BMIDI-5-35, BMIDI-1-35, BMIDI-2-35, BCC-1-3535, BCC-2-3535 | |
Size and Weight |
|
| Width | 117 mm |
| 4-5/8 inches | |
| Depth | 138 mm |
| 5-7/16 inches | |
| Height | (without rubber feet) |
| 63 mm | |
| 2-1/2 inches | |
| (including rubber feet) | |
| 65 mm | |
| 2-9/16 inches | |
| Weight | 800g |
| 1 lb 13 oz | |
| *0 dBu = 0.775 Vrms |
Boss, a division of Roland Corporation, has been a cornerstone of effects pedal design since the 1970s. Known for reliable, industry-standard gear that professionals and hobbyists alike depend on, Boss pedals are found on stages and in studios worldwide.
The brand's signature approach combines intuitive interfaces with powerful sound-shaping capabilities, allowing musicians to access complex effects without unnecessary complexity. Boss continues to innovate while maintaining the durability and ease-of-use that have defined its reputation for decades.

