Coherence II Series 2

About the Coherence II Series 2

The Jeff Rowland Coherence II Series 2 is a three-piece solid-state preamplifier featuring transformer-balanced inputs and outputs on XLR connectors. Released as an upgrade in April 1997, the Series 2 improved the attenuator amplifier circuitry using modern surface mount technology, resulting in wider bandwidth, faster setting time, reduced dielectric absorption, and greater thermal stability. It uses a dual high-current transimpedance output amplifier on a copper lead frame, enhancing clarity and resolution during complex music passages. The preamplifier is powered by an AC-assisted, microprocessor-controlled rechargeable battery power supply with two 12V, 7.2 amp/hour maintenance-free lead-acid batteries, providing up to 5-8 years of battery life. It offers 63.5 dB volume control range in 0.5 dB steps, preset gain range of 0-20 dB, frequency response from 0.5 Hz to 160 kHz (-3 dB), channel separation over 110 dB, and switchable input impedance between 18k and 600 ohms. The unit is housed in solid billet 6061 T-6 aluminum chassis, weighing approximately 83 lbs combined with power supply. The Coherence II Series 2 is highly regarded for its smooth, fluid, and relaxed sound with sonorous bass, wide and deep soundstage, and ultra-fine low-level detail, often compared favorably to high-end tube preamplifiers. It includes remote control functionality and a separate remote display unit with low-noise LED indicators. The preamplifier dimensions are approximately 17.5" W x 3.7" H x 10" D including power supply. The original The product is no longer manufactured but remains highly sought after by audiophiles.