AmpRX BrownBox Voltage-Reduction Unit

Vintage-Safe Voltage

AmpRX BrownBox Voltage-Reduction UnitAmpRX BrownBox Voltage-Reduction Unit
Price: $269.00 (list)
Contact: www.amprx.net

Amplifier repairman and builder Patrick Geraghty was frustrated with the sound of his own vintage-styled builds. They seemed to lack the vintage tones of the ’60s and ’70s. In addition to examining components, he also began to look at the disparity between the wall voltages of yesteryear and today. While most classic amps were built in the days of 110 volts, modern-day wall voltages are generally in the 120-129 range. When Geraghty lowered those voltages, he found that the amps opened up with more harmonic content, earlier compression, and a sweeter overall tone. With this revelation, he set out to create an easy-to-use device that would give gigging players lower era-correct voltages for their vintage and vintage-styled amps.

The AmpRX BrownBox is a voltage-reduction unit that features a simple two-knob design comprising a Primary Voltage Select knob and a Reduction Level knob, and an LCD backlit meter to display voltage and amperage levels. The sturdy powder-coated unit housing has a front-mounted 5-amp circuit breaker and a lighted On/Off switch.

We tested the BrownBox with a 1965 Vox AC30 and a 1974 Marshall JMP 50. Operation is fairly simple. Plug your amp into the BrownBox’s AC input, turn on the BrownBox, and check the readout. Then dial in the Primary Voltage Select knob to match the readout as closely as possible. The Reduction Level knob allows you to lower the voltage by a percentage of 3, 4, 6, 10, or 0 (for bypass). It is also possible to “brown out” your amp by setting the Primary Voltage knob to a voltage higher than reality and then using a high Reduction Level setting to starve the circuit.

Dropping the voltage down to 110 with the AC30 seemed to sweeten it, smooth it out, and give it a bit more compression compared to what the amp sounds like at 120 volts. Although it sounded nice before the voltage drop, the BrownBox certainly improved the sound at 110. The change was most dramatic with the Marshall, however. The tone seemed to fill out, “bark” more, and be less strident. With both amps, we loved their sound at 120 volts, but loved them even more at 110 and had no desire to go back.

If you are a vintage-amp connoisseur, experiment with yours at voltages in the range of 110 to 115. If you like what you hear, the AmpRX BrownBox is an ideal and handy solution for providing lower voltages to those prized vintage amps.


This article originally appeared in VG January 2015 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.