Collection: Products

Solidly built, and able to dial in any common output voltage setting between the two knobs. The knobs themselves are large enough to grip, with solid detents that won't slip or be bumped out of adjustment. I worried that, unlike a Variac where you have a wiper-style adjustment, I might not be able to get exactly the voltage I wanted, but have found this to be a non-issue with any normal wall receptacle power. My amps like getting the right power and, unsurprisingly, sound best at the input voltage they were designed to use! It is nice to always be sure they're getting the voltage, both for tone and component longevity.

makes my old Princeton sound better than ever

Such a great device to dial in my tube amps

I use this after my power conditioner to lock in the voltage for my Ampeg Heritage bass tube amp. We play in a lot of places with improper voltage and this is providing for consistent input voltage to my amp.

This is a "must have" piece of gear. I was getting ~123v out of the wall, which was not ideal for my modern stuff, and even worse for my new-to-me pre-CBS Bassman. Glad I got this; now I run it every time I plug in.

I’m thrilled with it. I’ve resisted getting one because I didn’t want to carry another device around, but it really sweetens up the tone of my amplifiers. I wish I’d bought one years ago.

Excellent Cable. Long enough for any stage. Well made.

Knobs tend to work loose after agjustments.

An amazing product. Anyone who owns vintage audio gear should have one…or MORE!

Wow - 114-115v for my 65 Tremolux made a HUGE difference in tone! I'm a believer.

This product has brought my tweed Fender Super, Blackface Twin Reverb, Valco and Danelectro amps back from the storage facility.
I have played electric guitar and bass for over 55 years, I remember how these, above mentioned, amplifiers should sound like and also perform like. Now, with The Brown Box, I am playing my vintage amps again. They have great tone and reliablity. That makes me happy. Thank you

Works great to stabilize input voltage for an older SuperLead

Required equipment for any tube amp. Built like a tank, these look as good as they perform!

The plate voltage on my vintage silver panel Deluxe Reverb is now in a safe range. I feel comfortable running vintage power tubes and it sounds so good. It has just the right amount of sag that was previously missing. Thanks AmpRx!

Yes, I know it's only January, but investing in my amp with a Brown Box was the smartest decision I've made in a long time. Thanks AmpRx. Now I'm safe and secure!