From AmpRX:

BrownBox was created to provide a safe range of voltage reduction levels for vintage tube amplifier designs. The same, era-correct voltage levels that the amps were designed around. our products can also be used with modern  solid state amp designs protecting them from potential over voltage conditions. 

The dynamics of a vintage amp supplied with the proper line voltage are optimized and will sound and respond as originally intended, revealing the circuits true harmonic content. This is the starting point, the basis of the signal chain, and where serious musicians begin creating a signature tone.  

Most vintage tube amps respond more harmonically and touch sensitive with optimized voltage . Placing these circuits  back into  balance reveals the authentic tone fundamental of the amp, tone that can truly blossom. 

For the Tube Tone Purist, no pedal or attenuator can come close to replicating the heavenly response of dry, purely saturated tubes. Pedals and attenuators have their place, keeping in mind that they color your tone, not create it.

Everyone can enjoy multi-dimensional, pure tube tone, if they just know where to start. 

BrownBox is not a variac. Unlike a variac, Brownbox cannot accidentally harm or destroy your amplifier. The maximum input voltage available using BrownBox is your regional line wall voltage, in bypass mode. All other selections are reduction levels that you determine sound best for your amp. 

BrownBox  employs a proprietary  custom -wound toroid  transformer, intended for use with one amplifier. check you amps input wattage  rating  prior to use. Our proprietary transformers  are custom wound exclusively for use with tube amplifier designs, but can and should be used with Solid state circuits  - 

Technical background interest
 Consider this: testing with  a non-modded vintage fender Bassman ( 5F6A) as part of our testing platform throughout the design process, one of the most important electrical design elements was measuring the variable current levels that the amp would draw at different line levels.

Testing was  performed at control levels  between 105 V.A.C. to 126 V.A.C . 

Testing indicated  current  levels of  0.7 and 1.8  amperes consecutively. 

Knowing those factors enabled us to build in exceptional electrical stability by creating a transformer with a current rating 2.5 times greater than the highest test level result of 1.8 amperes. 

BrownBox was created by a team of experienced player/ technicians with the professional player in mind. That meant first it must be intuitive and easy to use every time. Secondly, it must also have a road rugged design and be able to take abuse. Thirdly, it must be practical  and superior to any other voltage reduction option.

BrownBox  is completely proprietary in design and function and comes with a lifetime warranty with normal use. 

• Easy to read, back-lit L.C.D. display enabling real-time voltage and amperage monitoring, also useful for diagnostics.
• Tough road rugged construction.
• Proprietary  transformer designs wound exclusively for use with tube amplifiers, an industry first!
• Filament soft-start in full reduction mode. 
• A powder coated EMF  neutral housing.  In-rush current protection, fused over-load protection .
• Silent , cool operation.
• Custom wound 5 amp proprietary  transformer that will supply 540 watts max@ 120 Vac. Designed for Mid  to larger sized Amps , Fender Bassman, Marshall 50s/100S  Etc or for  Parallel or( DUAL)  amp rigs. Be sure to check the manufactures info plate  on the  rear of the chassis  for input watt requirements or  simply call us, we love to help.
• 5 year parts and labor. 
• Made in the USA.