Friday, September 10, 2021


 UNIVERSAL AUDIO OX AMP TOP BOX     $1299 street price

Universal Audio is a popular brand of DAW technology so when they came out with the OX I wondered what it was like. The OX is physically one of the largest impulse response technology devices reviewed here. It is also one of the most technically sophisticated with the most included integrated options for shaping your sound.

The OX package feels solid and heavy duty. The faux wood trim on the front seems a bit silly and unnecessary to me but it’s not an unattractive processor.

When it comes to performance the OX delivers a lot of options. UA did a good job of endowing OX with some easy to use features without resorting to iPad or USB. When you’re ready to dive in OX offers unmatched tweakability.


The OX is made to sit on top of your guitar amp which helps keep all the connecting cables short and the controls accessible. 

The OX has an internal “room simulation” algorithm which is selected by a front panel rotary switch.

OX is an impedance adjustable “reactive load”. On the back panel you can select the impedance to match the output of your amplifier, 4, 8 or 16 ohm selections are available.

OX has TRS balanced stereo outputs which are capable of outputing +20 dBU maximum signal level.

OX has several hardware controls to assist you in using it. A rotary selector switch labeled “Rig” lets you choose between preprogrammed speaker and microphone combinations. It comes stock with some useful settings already installed. Software allows you to modify and store your own “Rigs” inside OX.

If you play through OX to an optionally connected speaker a front panel selector switch allows you to attenuate the output of sound coming from the speaker.

OX has a lot going for it with many sonic options available and the front panel hardware controls are convenient for the user to access while playing and experimenting. 


OX does not have balanced microphone level outputs so you’re going to need a good stereo direct box to connect it to microphone preamps. Directbox connections provided the best way to not get ground loop hum using OX with high gain tube amps like Boogie and EVH. The Klark Teknic DN200 stereo direct box works great at converting OX 1/4” line outputs to balanced mic-level with ground lift.

OX acts like a self contained wifi router, the process of registering your software and then getting the iPad connected directly to OX is convoluted and unpleasant.

The speaker attenuator function works but the guitar amp tone is changed as you move to lower volume levels. Every single power attenuator I’ve ever used has changed the sound of the amp for the worse. The Cab I.R. functions sound wonderful so maybe use them driving another amp stage or the input to your DAW. 

I found the included speaker cabinet response simulations to be much less exciting than just playing through a real speaker. I have six 4x12 cabinets so I’m very familiar with the sound of the real thing.

You gotta have an iPad connected to OX to get all the controls available. Pairing the iPad wifi to OX becomes a pain on a day to day basis. You must have a wifi network with internet access to register the OX software, you only need this once but it is a must have. 


This is one heavy box, no I mean this thing is surprisingly, physically heavy. 

I like the OX. It offers a highly useful and integrated package with the most options for onboard modifying your tone and making it sound like you want to hear it. OX is one of the most expensive reactive load options. You’ll want to budget for a stereo direct box and an iPad to get the maximum control live or in a studio situation.

Thanks for reading High on Technology, Good Music to You!

©Sept 2021 by Mark King, It’s not ok to copy or quote without written permission. Thanks