Audio Research Reference 2MKII

The Reference Two Mk II is a large single-box fully balanced preamp measuring 19"W x 7"H x 15 1/2"D and weighing 31 pounds. Audio Research-supplied specs are impressive: .5Hz-60kHz frequency response, less than .015% distortion, noise that's 100dB below the 2V RMS balanced output. The Reference Two Mk II's internal cavity is divided into three sections, with four separate circuit boards occupying the space: the micro/control circuitry in front, then the power-supply board, the audio section, and finally the input/output relay section at the rear. The circuit boards are isolated from each other to reduce the chance of sound-degrading interactions. This layout also gives ARC engineers more room than a single circuit board while allowing for modular upgrades.

Tubes used are the previously mentioned half-dozen 6H30s along with a single 5AR4 and 6L6GC in the power supply. Estimated tube life is 4000 hours. Of particular note is the Reference Two Mk II's gain control, which is actually a spring-loaded two-way switch that adjusts the volume either a step at a time (in 125 increments!) or continuously. A ring of LEDs around the edge indicates the volume level of the preamp. The balance control works the same way, with many fewer adjustment increments. Also on the front panel are input and record selectors along with the power on/off, mute, and phase switches. There is also a switch for determining if a particular input will operate from its balanced or single-ended inputs. This kind of flexibility in what is a fully balanced design certainly adds considerably to the Reference Two Mk II's cost, but ARC provides it because not everyone is fully balanced. (Speak for yourself!)

The Reference Two Mk II's rear panel is absolutely packed with RCA and XLR inputs and outputs -- only a surround-sound processor will rival it for sheer number of jacks. There is also an IEC power-cord receptacle, fuse holder and +12VDC output jack that provides continuous voltage for remote-start electronics when the Reference Two Mk II is on.

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