Pre/Power Amplifiers

Careful evolution best describes the path of ARC's single-chassis Reference preamps, which started with the REF 1 in 1995, notable for its resemblance to 'classic' ARC preamps with its row of knobs above toggles, between handles. Its gain was all-tube, with eight inputs, but with full microprocessor control of volume, balance, record and input selection. It also featured fully regulated power supplies, dedicated analogue and logic transformers and audiophile-grade components throughout. The REF 2 from 1998 looked the same and allowed '1s to be upgraded to '2s. A unity gain stage was added, as was tube regulation. The REF 3 of 2004 was a full re-design, now featuring a fluorescent display and menu that replaced many controls.

With the REF 5 of 2009 – the blueprint of today's REF 6SE – the circuit design was revised again, now fully balanced and operating in pure Class-A triode mode, but the basic look remained the same. Its valve complement comprised four 6H30s in the audio stage, with a 6550 and a 6H30 in the power supply. For the REF 6, ARC introduced an additional 6H30 stage per side, maintaining the same overall gain and low noise but significantly reducing distortion. The REF 5 and 6 also ushered in the latest volume circuit – offering a useful 66dB range over 102 steps (from 0-103, with '0' putting the preamp into mute). The volume increments average out at ±0.3dB over the top 60dB of the REF 6SE's dynamic range (103 down to 43), ±0.9dB over the following 30dB (43 to 13) and ±1.5dB right down to '1' on the volume scale. PM