3BX II

About the 3BX II

The DBX 3BX Series II (also known as 3-BX Mk II) is a sophisticated dynamic range expander designed to restore the dynamic range lost between the original performance and the listening environment. It divides the audio spectrum into three separate frequency bands (bass, midrange, treble) and expands each band individually using multiple true RMS detectors and voltage-controlled amplifiers. This approach prevents bass notes from artificially elevating midrange sounds and midrange crescendos from bringing high-frequency information unnaturally forward, preserving musical integrity. The unit features adjustable expansion ratio up to 1.5:1, transition level control, and LED indicators showing expansion activity. It includes source/tape and pre/post switches for flexible integration with tape decks. The 3BX Series II is highly regarded for its ability to expand complex program material with minimal artifacts, enhancing impact recovery and ambiance to bring the excitement of live music closer to the listener. It was manufactured circa 1982 and originally The unit typically comes with rack mounting wings and factory packaging, and is known for excellent operational condition even decades later.