AmpRx creates products that help you supply your gear with the correct voltage

Here’s the quick rundown: The BrownBox is an adjustable AC power supply for your amp or tube gear that helps you run your equipment at the optimal voltage. Plug the BrownBox into the wall, adjust the voltage and then plug your gear into the BrownBox.

When a tube amplifier is supplied with the proper line voltage, it will sound and respond as originally intended, revealing the circuit’s true harmonic content, and preventing unnecessary, expensive, and frustrating repairs.

BrownBox users testify time and again as to how their amp’s tone, touch and feel have finally come together, providing them with improved harmonics and dynamic amp performance- allowing them to capture the elusive tone they’ve always wanted, every time, everywhere.

Learn more about why Voltage Optimization is importantShop products

NEW! THE BROWNIE IS HERE

The Brownie by AmpRx is the latest innovation in voltage optimization, providing musicians with unparalleled control, flexibility, and protection for their gear. Designed specifically for modern tube amplifiers, the Brownie is a voltage controller offering the option to increase and decrease voltage. The Brownie is the ultimate solution for achieving consistent tone and protecting valuable equipment - the first of its kind.

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WHAT PEOPLE ARE SAYING ABOUT THE BROWNBOX

Game changer

Love this thing. My amp sounds better and the customer service and ease of use is incredible.

Aaron V | Dec 2024

Verified

High quality!

This is a tour grade, durable little box! Easy to dial in, and a good safety measure for spikes in power etc. I also like that you can feel a differences. For my '65 Bandmaster head, I find that the BrownBox smooths out the high end and gives the response a fuller, rounded out feel by lowering the voltage to 117v. Thank you AmpRx

Zach A | April 2, 2025

Verified

It's Great!

I don't know how you can build it like that and sell it for what you charge thanks

Harold L | May 2024

Verified

Don't leave home without it!

If you want your amp to be consistent between home, rehearsal, stage, and studio, just buy one. Carry it with you and use it everywhere. It's killer. Then buy at least one spare just in case.

Aaron S | Jan 2025

Verified

I am happy with the BrownBox!

My amp (Fender Super Champ) runs cooler now with the voltage down to 106 volts (recently I had to replace blown tubes) and it sounds better. Easy interface. I am happy with the BrownBox!

Chris N | Feb 2023

Verified

Awesome!

Built to a high standard and works just as advertised. I look forward to using my Brown Box for a long time and can rest assured that my tubes will have a nice long life as well. Not to mention that my amps can perform at the voltage that they were intended to. Fast shipping and easy easy transaction. Would recommend this product to anyone looking to protect their amps and tubes and get the right voltage and unlock the real potential of their amps!

Alexander H | May 2024

Verified

BROWNIE VS BROWNBOX

CHECK OUT THIS EPIC SHOUTOUT FROM DR.Z!

The Doc himself included us in this great video from Dr Z Amplification about how to make your tubes last longer. We recommend watching the whole thing (there’s a ton of really important info), but if you want to hear exactly what he has to say about BrownBox, skip to 6:18! The whole video is packed with great advice! Thanks, Doc!

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