Universal Audio OX Amp Top Box Guitar Recording System and Reactive Load

The OX allows you to play your tube amp in its tonal sweet spot—from pristine cleans and edge-of-breakup grit to fully saturated distortion—at any volume level, from whisper-quiet to stage volume. Universal Audio designed the OX to provide the same tone, dynamics and responsive feel of a real speaker cabinet so you can experience your amp's natural tone like never before. Just plug your amp's speaker output into the OX and your cabinet into the OX's output to enjoy the true tone of your amp at any volume.

Dial in Legendary Studio Tones

The OX offers more than just reactive load attenuation. Its front-panel six-position "Rig" control provides complete mic and cab setups—including 22 vintage and modern cabinets loaded with iconic speakers from Celestion, Jensen, JBL and more, close mics, room mics and up to four simultaneous studio effects. The OX is the only product that offers a selection of expertly placed room mics, providing an authentic studio tracking room experience while recording your cranked amp.

Dynamic Speaker Modeling for Organic Tone

The OX utilizes Universal Audio's Dynamic Speaker Modeling technology to faithfully emulate speaker breakup, drive and cone cry, which is essential for reproducing the complex harmonics and sonic nuance of a real tube amp and speaker cabinet. Using the Speaker Breakup knob in the OX app, you can control the harmonics and sonic complexity that only occurs at certain frequencies and volume levels on various speakers—far beyond a static Impulse Response system. This gives you the same phenomenon that happens with an actual speaker cabinet.

Intuitive Software Control and Connectivity

The OX software app offers simple, intuitive control over all of the OX's parameters via Wi-Fi, letting you tweak, store and recall hundreds of presets from your iPad, Mac or Windows 10 computer. You can then save your six favorite sounds to the OX's front-panel Rig knob for instant recall. The OX also features a headphone jack for silent practice with your cranked tube amp, balanced TRS line outputs, S/PDIF digital outputs and footswitch connectivity.

UAFX 2.0 Firmware Update

Launching November 11, 2025, the UAFX 2.0 firmware update delivers a major performance upgrade to Universal Audio’s two-button pedals, unlocking deep MIDI integration, enhanced footswitch control, and streamlined app connectivity. Players can now select from four new footswitch modes—Live/Preset AB, A/Bypass + B/Bypass (Tour Mode), A/B–C/D, and Boost + Live/Preset—ideal for live “channel-switching” workflows. The update introduces 128 recallable presets via MIDI Program Change, real-time parameter control through MIDI CC messages, and MIDI beat clock sync for time-based effects including the Starlight Echo Station, Astra Modulation Machine, Galaxy ’74 Tape Echo & Reverb, and Del-Verb Ambience Companion. Bluetooth connectivity has been rebuilt from the ground up for increased reliability, while a new wired USB connection enables direct app control from iOS or Android devices. USB MIDI support further enhances expression, preset switching, and clock sync capabilities, making it easier than ever to integrate UAFX pedals into modern performance rigs. All updates are free and compatible exclusively with dual-footswitch UAFX models.

The Universal Audio OX Amp Top Box is a premium recording system and reactive load box that gives guitarists the ability to achieve perfectly studio-miked amp tones from their favorite tube amplifier anywhere, at any volume level. Featuring Universal Audio's groundbreaking Dynamic Speaker Modeling technology, the OX emulates speaker drive, breakup and cone cry like no other product on the market.