Universal Audio OX Guitar Amp Top Box with DSP Modeling

Guitar Amp Top Box with DSP Modeling, Room and Cabinet Emulations, and mobile app control

Get the ultimate tone from your tube amp – anywhere, at any volume.


Special 12-Month No-Interest Financing.


The Universal Audio OX Amp Top Box is an amp top box reactive load that enables you to get the most realistic response from your tube amp combined with UAD-2’s world-class mic/cab, EQ, compression, and reverb emulations.

The Universal Audio OX is the solution for guitarists who want to make great recordings with the response and sound of their tube amp, but don’t have a five-figure front end, or a treated/sound-proof space. A premium reactive load box that provides an analog modeled circuit that accurately emulates the response of a speaker cabinet, the UA OX Amp Top Box lets you silently record your tube amp at any volume level and still enjoy all the sonic sweet spots; from mild breakup to full-on cranked. And you can do so with Universal Audio’s record-quality mic, speaker cabinet, and room ambience emulations simply by twisting a knob.

Universal Audio OX Amp Top Box in one take:

  • Premium, no-compromise analog reactive load box for tube guitar amps
  • Five finely-tuned guitar amp attenuation levels, from whisper quiet to full volume
  • Front-panel “Rig” control for album-quality mic and speaker cabinet emulations at the turn of a knob
  • UA Dynamic Speaker Modeling emulates speaker breakup and cone-cry
  • World-class Universal Audio EQ, compression, delay, and reverb effects built-in
  • Selectable 4, 8, and 16-ohm operation
  • Front-panel headphone output for silent practice
  • Balanced TRS line outs, and S/PDIF digital outputs for stereo recording
  • Pair with OX mobile or desktop app over Wi-Fi for editing and saving presets
  • Built for years of home and studio use

No-compromise reactive load

Without presenting a load* to a tube amp in the form of a speaker cabinet, damage will occur, since there’s nothing to dissipate power. There are two methods to creating a load: resistive and reactive. A resistive load is a series of resistors that draws power and dissipates it as heat, which is what a tube amp needs in order to survive. A reactive load is a passive analog model of an actual speaker cabinet. It comprises several RC (resistor and capacitor) circuits with specific electrical proportions to emulate the exact response of a speaker cabinet.
Since the reactive load presented to the amp is able to produce the non-linear characteristics of a speaker cabinet, the amp responds exactly the way it would if connected to a physical speaker cabinet. It also has the added bonus of having the guitar retain the same feel and dynamics as it would through an amp and speaker cabinet.

*Load: a circuit that consumes power, usually something that does work, such as a motor or speaker cabinet

Universal Audio’s world-class emulations

Renowned throughout the professional audio industry for stunning emulations of analog gear, UA brought its expertise to bear on creating the most realistic speaker modeling available. The result is their breakthrough dynamic speaker modeling, which responds to your amp and guitar volume knob just the way a 4-, 8-, or 16-ohm speaker cabinet would. OX gives you authentic “edge of destruction” tones, emulating speaker breakup and cone-cry like no other resistive or reactive box on the market. It is perhaps the world’s finest boutique speaker attenuator and complete guitar amp recording solution.

Not only do you get the optimal response from your tube amp along with the realistic response you’d get from your guitar playing through a live rig, the OX Amp Top Box also lets you record with UAD’s record-quality mic and guitar cabinet setups, plus EQ, dynamics, and reverb emulations used by the industry’s top mixers.

Whether you’re recording in your bedroom, pro studio, or silently practicing your most brutal metal licks in order to visit sonic devastation on an unsuspecting populace, the Universal Audio OX Amp Top Box lets you do it all, with industry-leading UA sound and fury. For more information, call or chat online with your Westlake Pro Sales Consultant today.

Additional information

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Westlake Pro Card

On purchases with your Westlake Pro Card interest will be charged to your account from the purchase date if the promotional purchase is not paid in full within 12 [or 6] months. Minimum monthly payments required.

Qualifying purchase amount must be on one receipt. No interested will be charged on the promo purchase if you pay it off, in full, within the promo period. If you do not, interest will be charged on the promo purchase from the purchase date. The required minimum monthly payments may or may not pay off purchase by the end of the promo period. Regular account terms apply to non-promo purchases and, after promo ends, to promo balance. For new accounts: Purchase APR is 29.99%; Minimum Interest Charge is $2. Existing cardholders: see your credit card terms. Subject to credit approval. 

Promo ends 6.31.20

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