Many Unison Research customers have expressed the wish for an all-tube pure class-A power amplifier with a power output significantly higher than any previous Unison product. In order to satisfy this request, the Unison Research design team has created a single-ended monoblock amplifier able to deliver 80 watts in pure Class-A. This product has become the first in a new line which embodies all our experience in valve amplifier design acquired over the years–the Reference Series.
Having completed the power amplifier project, a preamplifier of similar quality and performance was added, and it is fully worthy of inclusion in the Reference Series. We have named it, of course, the Reference PRE.
From the outset it was decided to create a circuit without compromise. The Reference PRE has a dual mono layout within a triple chassis to give full separation of the power supply stage from the line and phono stages. Input switching by two-stage relays has been added to eliminate any possible diaphony. The way we have labored over the details, which shows in every aspect of the design and appearance of the Reference PRE, is truly worthy of the finest Unison Research products.
To briefly summarize the characteristics of the Reference PRE, the output stage employs one
300B tube and is able to supply an undistorted output voltage of 25V over a bandwidth which extends to above 100kHz. The volume control is a top quality ALPS model from their HQPro Audio Series, a truly excellent unit from a manufacturer that has been preferred by Unison Research from the very beginning.