The Universal Audio UAFX Ox Stomp is a cab and mic emulation pedal from Universal Audio, priced at $3991. Rather than a basic IR pedal that loads static impulse responses, it uses UA's Dynamic Speaker Emulation, and it also builds in a 1176 compressor, digital delay, and room and plate reverb1. You can set up six preset "Rigs" on the app to switch between on the physical pedal1.
Guitar World's reviewer found the emulation lived up to its billing, calling it2:
"UA's Dynamic Speaker Emulation truly lives up to its name by providing dazzlingly authentic speaker and miked room tones"2
What the OX Stomp does
The pedal is basically the rig section of UA's OX Amp Top Box: the speaker, room and mic emulation plus the effects, without the reactive load box, headphone amp and digital connections of the full-size unit2. Guitar Pedal X described it as delivering much of the OX Box's speaker, cab, mic and room modeling in a stereo pedal3.
Its emulation covers three layers:
- Speakers and cabinets: UA's curated speaker and mic models, managed through the app rather than third-party IRs1
- Microphones: dynamic, ribbon and condenser mic emulation1
- Room: room emulation with its own level control on the pedal1
On top of that sit the effects: 1176 compression, plate reverb, EQ, stereo delay and modulation1. The delay offers five stereo modes, Dual, Crossover, Ping Pong, Chorus and Flanger, which MusicRadar's reviewer called "a stereo delight"1. The 1176 compressor controls live in the app and mirror the core parameters of UA's standalone 1176 pedal1.
You cannot upload third-party IRs to the OX Stomp. Speaker and mic models are UA's own, uploaded via the UAFX Control app. As MusicRadar's reviewer put it: "So while you can't upload third-party IRS to the Ox Stomp, you're getting UA's top notch effects as part of the deal."1
The controls and the six Rigs
The pedal's surface controls are straightforward, with the deeper editing pushed to the app1:
| Control | What it does |
|---|---|
| Rig selector | Chooses between preset Rigs |
| Speaker Drive | Adds to the amp feel; increasing it gives a springier feel to the response as it breaks up easier1 |
| Mic 1 mini toggle | Chooses the mic type for mic 1 |
| Mic 2 mini toggle | Chooses the mic type for mic 2 |
| Mic 1 level | Sets mic 1 level |
| Mic 2 level | Sets mic 2 level |
| Room level | Sets the room emulation level |
| Output | Sets output level |
All controls and functions from MusicRadar's listing1.
You can set up six preset "Rigs" in the app and switch between them on the physical pedal, using the two footswitches to select Rigs, reverb or delay1. The Bluetooth UAFX Control app gives access to deeper editing, effects and presets, some based on famous artist sounds1.
MusicRadar's reviewer flagged the app reliance as the pedal's main drawback, calling it oddly regressive compared with analog pedals and noting that this is not a set-and-forget pedal because a lot of crucial features can only be activated and changed in the app1. Universal Audio pushed firmware 1.1.7 to all Bluetooth-enabled UAFX pedals in November 2023 to address Android 14 connectivity issues with the app12.
Power and connections
The OX Stomp runs on a 9V DC pedalboard isolated power supply with a 400mA draw1. That current requirement rules out a battery and means it needs a proper isolated supply rather than a shared daisy chain.
The rear panel carries pairs of TS ¼-inch stereo inputs and outputs, unbalanced, giving the pedal its stereo operation2.
There is no headphone output and no XLR output. MusicRadar's reviewer found the lack of a headphone out frustrating, and noted that the lack of XLR means you need something like the Walrus Audio Canvas to go straight to the desk1.
What reviewers said
Reviews were broadly positive about the sound, with reservations about the app and the omissions1.
- Guitar World: The reviewer preferred the sound of the OX Stomp to the IRs in several expensive amp modelers he owned, and found the speaker and miked room tones authentic2.
- MusicRadar: The verdict praised "UA's established benchmark speaker and mic emulations and control over them" plus the included premium EQ, compression and effects, calling the plate reverb, 1176 compression and delay a huge plus and a great potential pairing with a preamp pedal, while noting that the omissions and app issues undermine it somewhat1. The reviewer saw the ideal user as someone fully invested in pedal amps who wants more scope for home, live and recording scenarios1.
- Premier Guitar: The review highlighted that the pedal emulates the environment around the cabinet, including room and microphone type, alongside UA compressors, delays and reverbs4.
"In addition to UA's established benchmark speaker and mic emulations and control over them, the included premium EQ, compression, delay and reverb features make this an even more powerful pedalboard rig addition."1
For players comparing it against other cab and mic emulators in the speaker simulation category, the OX Stomp's distinguishing points are the dynamic (non-IR) speaker modeling, the built-in 1176 compressor, delay and reverbs, and the six-switchable Rigs, set against the absence of third-party IR loading, headphone and XLR outputs1.
Videos
Andertons Music Co
Sweetwater
Universal Audio
News
Questions
Can you load third-party IRs into the UA OX Stomp?
No. The OX Stomp does not accept third-party impulse responses. Its speaker and mic models are Universal Audio's own, uploaded and managed through the UAFX Control app. MusicRadar's reviewer framed this as a trade-off: you give up third-party IRs but you get UA's effects, including the 1176 compressor, delay and reverbs, as part of the deal.
Does the OX Stomp have a headphone output?
No. MusicRadar's reviewer found the lack of a headphone output frustrating. The pedal's outputs are pairs of unbalanced TS quarter-inch stereo jacks, so private listening requires extra gear rather than a headphone jack on the pedal itself.
Does the OX Stomp have an XLR output?
No. MusicRadar's reviewer noted that the lack of an XLR output means you need something like the Walrus Audio Canvas if you want to go straight to the desk. The pedal's rear panel carries pairs of TS quarter-inch stereo inputs and outputs, unbalanced.
Do you need the UAFX Control app to use the OX Stomp?
You can use the pedal without it, but not fully. MusicRadar's reviewer called the OX Stomp not a set-and-forget pedal because a lot of crucial features can only be activated and changed in the Bluetooth UAFX Control app, including deeper editing, effects and presets, some based on famous artist sounds.
Can you use the OX Stomp with a real tube amp head?
Not as a load box. The OX Stomp is basically the rig section of UA's OX Amp Top Box, without the reactive load box, headphone amp and digital connections. It is a line-level pedal, so it emulates speakers, mics and rooms but does not absorb a tube amp's output the way the full OX box does.
Sources (4)
- Universal Audio UAFX Ox Stomp Dynamic Speaker Emulator pedal review, MusicRadar, 2023-12-14
- UAFX OX Stomp Dynamic Speaker Emulator review, Guitar World, 2024-01-31
- Guitar Pedal X, Guitar Pedal X, 2023-10-05
- Discover UAFX OX Stomp: Tone Mastery, Premier Guitar, 2024-05-18
