The Universal Audio OX Stomp is a Dynamic Speaker Emulator pedal: a stereo stompbox that emulates speakers, cabinets, microphones and rooms, with studio effects built in. Universal Audio positions it as the companion piece for "amp-in-a-box" modeler pedals, giving them what the maker calls "a packed pro studio full of authentic-sounding" cab, mic and room tones.1
It descends from the company's OX Amp Top Box, carrying much of that unit's speaker, cab, mic and room modeling into a compact pedal, but without the reactive load box feature that some guitarists did not need.12 Guitar Pedal X's Stefan Karlsson described it as delivering "much of the OX Box's speaker, cab, mic and room modelling in a stereo pedal."3
What It Does
The core of the pedal is Universal Audio's Dynamic Speaker Modeling, which the maker says "convincingly emulates speaker breakup, drive, and cone cry."1 Where a conventional impulse-response cab sim captures a static snapshot of a miked cabinet, Dynamic Speaker Modeling is designed to respond to the level hitting it, reproducing the way a real speaker's behavior changes as it is driven harder. Delicious Audio's Paolo De Gregorio described the result as "providing harmonics and sonic complexity indistinguishable from a perfectly studio-miked speaker cabinet."6
A Speaker Drive knob lets you simulate the sound of the input of the cabinet breaking up, so the pedal can add speaker breakup on top of whatever amp model feeds it.6
The emulation covers the full studio chain:
- Speakers and cabinets: 22 different speaker emulations, ranging from 1x10 and 1x12 cabs to various 4x12s7
- Microphones and rooms: mic and room modeling delivering much of the OX Box's speaker, cab, mic and room modeling in a stereo pedal3
- Speaker modeling: Dynamic Speaker Modeling, which Universal Audio says emulates speaker breakup, drive, and cone cry1
- Presets: over 100 curated RIG setups, which Universal Audio says give "inspiring sounds for any amp type or genre, right out of the box"1
Guitar Pedal X summed up the maker's claim as "The most authentic sounding speaker, cab, mic, and room tones ever emulated in a pedal."3
Controls, Connections and Power
The pedal has two footswitches. The second can be configured via the app to trigger specific effects or to act as a mirror of the A footswitch.6
Deep editing happens in the UAFX Control mobile app, connected by hardwired USB or Bluetooth, where you can swap cabs and mics, fine-tune effects, assign RIG presets and configure the footswitches.1 The pedal also fits into a programmable MIDI rig through its rear-panel USB-to-MIDI connection, receiving preset changes and realtime control of effects and EQ.1
| Connection | Detail |
|---|---|
| Inputs | 2 x 1/4" unbalanced TS, input 2 for stereo1 |
| Outputs | 2 x 1/4" unbalanced TS, output 2 for stereo1 |
| Input impedance | 500 kilohms (mono in), 1 megohm (stereo in)1 |
| Output impedance | 500 ohms1 |
| Max input level | 12.2 dBu1 |
| Max output level | 12.1 dBu1 |
| Frequency response | 20 Hz to 20 kHz, ±1 dB1 |
| USB | Type-C, for registration and firmware updates via computer1 |
| Bluetooth | v5, 2.400 to 2.4835 GHz, +4.35 dBm maximum output power1 |
The OX Stomp requires an isolated 9V DC center-negative supply delivering at least 400 mA, through a 2.1 x 5.5 mm barrel connector (the same as standard Boss connectors). The supply is sold separately, and the 400 mA draw rules out battery power and most simple daisy chains.12
Physically it is a compact pedal: 2.56 inches high, 3.62 inches wide and 5.55 inches deep including knobs and protrusions, weighing 1.3 lbs (0.588 kg) unboxed.1
Where It Came From
The OX Stomp is descended from Universal Audio's award-winning OX Amp Top Box, carrying its speaker, cabinet, mic and room emulation into a stompbox.1 As one retailer put it, some guitarists didn't need the reactive load box feature of the OX, they just wanted the cabinet, mic, and room emulations, and the OX Stomp is that pedal version, without the reactive load box.8 It lists at $400.1
Gearnews noted the reasoning behind the format: "some guitarists didn't need the reactive load box feature of OX, they just wanted the cabinet, mic, and room emulations."2 The OX Stomp is that product: the emulations without the load box.
What Reviewers Said
guitar.com's Cillian Breathnach reviewed it in December 2023 and noted that "this pedal still costs $400."5
One reviewer's overall verdict was that the pedal offers many options and tones, concluding that "this unit continues UA's magnificent run of amazing pedals."9
"this unit continues UA's magnificent run of amazing pedals"
How It Compares
As a speaker and cab emulator in pedal form, the OX Stomp sits alongside other cab-simulation pedals such as the Two Notes Torpedo C.A.B. M, the MOOER Radar and the NUX Solid Studio, and next to amp-and-cab pedals like the Strymon Iridium and Walrus Audio Mako Series MKII ACS1. Its distinguishing feature among these is Dynamic Speaker Modeling with its level-responsive breakup, plus the mic and room modeling inherited from the OX Amp Top Box. See the speaker simulation pedals overview for the wider field13.
Videos
Andertons Music Co
Sweetwater
Universal Audio
Questions
What does the Universal Audio OX Stomp do?
It emulates speakers, cabinets, microphones and rooms in a stereo pedal, using Universal Audio's Dynamic Speaker Modeling to reproduce speaker breakup, drive and cone cry. It is designed to sit after an amp-in-a-box pedal, giving it a modeled cab, mic and room plus built-in studio effects.
How is the OX Stomp powered?
It needs an isolated 9V DC center-negative supply delivering at least 400 mA, through a 2.1 x 5.5 mm barrel connector, the same as standard Boss connectors. The power supply is sold separately, and the current draw rules out battery power and most daisy chains.
How does the OX Stomp differ from the OX Amp Top Box?
The OX Stomp is a line-level pedal version that carries the speaker, cab, mic and room emulations of the OX Amp Top Box but leaves out the reactive load box feature. It suits players who do not need to load down a real tube amp.
How much does the OX Stomp cost?
It launched at $399 in September 2023, and guitar.com's reviewer noted it still cost $400 as of December 2023. Gearnews listed it at 439 euros at Thomann at launch. Check current pricing with retailers.
Sources (9)
- OX Stomp Dynamic Speaker Emulator Pedal, Universal Audio
- Universal Audio OX Stomp Dynamic Speaker Emulator pedal, gearnews.com, 2023-09-26
- Guitar Pedal X, Guitar Pedal X, 2023-10-05
- Ox Stomp by Universal Audio, RockBoard PedalPedia, 2026
- Universal Audio OX Stomp: world-class cab sim hampered by tech issues, guitar.com, 2023-12-08
- UAFX Universal Audio OX Stomp, Delicious Audio, 2023-12-04
- UAFX OX Stomp Dynamic Speaker Emulator review, Guitar World, 2024-01-31
- The missing piece for your ultimate pedalboard rig? Universal Audio announces the OX Stomp Dynamic Speaker Emulator pedal, MusicRadar, 2023-09-26
- Universal Audio OX Stomp Dynamic Speaker Emulator, Pedal of the Day, 2024-01-25
