Octave Audio HP300SE

A direct descendant of the HP 300 MK2, the HP300SE sits at the top of Octave Audio's range of valve preamplifiers. It acts as the switching and gain centre of a hi-fi system: it receives the sources, sets the level and drives one or more power amplifiers, via unbalanced as well as balanced connections.

Its power supply is housed in a separate unit containing the transformer and optimised mains filtering, while the precise, low-noise voltage regulators remain in the main chassis. This arrangement, combined with a revised line stage, aims for a high signal-to-noise ratio and limits the influence of mains-borne interference. The balanced output relies on a balancing transformer whose earth can be connected or disconnected, in order to eliminate earth loops between the preamplifier and the power amplifiers. The very low output impedance of the XLR and RCA connections also allows interconnect cables of up to 10 m without altering the signal sent to the amplifier.

The connectivity covers two independent XLR inputs and three RCA inputs, complemented by two RCA outputs, one XLR output and one monitor output. The latter can feed a headphone amplifier, a recorder or the analogue-to-digital conversion input of a computer, as required. A phono card, in MM or MC version depending on choice, can be fitted as an option, with the MC input offering several loading adjustments. A multichannel bypass, active on either an RCA or an XLR input as selected, finally allows the preamplifier to be inserted into a home cinema system.

This model is aimed at listeners building a system around one or two power amplifiers who wish to retain the character of a valve stage without giving up a quiet background or balanced connection. The number of inputs, the monitor output and the phono option suit systems combining several analogue and digital sources; the multichannel bypass meets the needs of installations where the same pair of front speakers is used for both music listening and cinema.