The Enlightened
Preamplifiers

Preamplifiers are the heart of any system. From the beginning, OCTAVE has developed first-rate separate preamplifiers. The interface between the low level sources such as turntable and the high level/high current output stages is quite complex and there are many considerations to take into account. There are always interactions between the preamp and the other components in the system, thus the power supply of the preamp becomes extremely important.

The HP 300 MKII belongs to a new generation of OCTAVE preamps derived from the experience gained during the development of the Jubilee preamp. The implementation of a Super Gain/ High Current Output Stage technology improves the line amplifier in all aspects, offering extremely low distortion and very low output resistance. Perhaps the most important aspect is that the sound quality of the tube based stage is independent of the output load and the cable capacitance. The power supply is specifically designed for the HP 300 and includes a highly efficient, low magnetic stray-field transformer. The extensive features of the HP 300 MKII make it an ideal preamp for any high-end audio system.

The HP 300 MKII features a total of five single-ended (RCA) inputs, one balanced (XLR) input, while outputs included are one RCA Record output, two pair of RCA and one pair of XLR outputs.

Home Theatre

The Home Theatre pass-through function allows bypassing the AUX input direct to the RCA output, with the signal being converted into the balanced mode and also present on the balanced (XLR) outputs.

Tape Monitor

The Tape Play and Record input section is connected in the classic manner which allows monitoring of the signal, which is recorded at the same time. The Record output is buffered to minimize interaction with any type of recording equipment.

Power Management and Protection System

The preamplifier is equipped with a multistage Turn-On/Soft-Start electronic protection circuit to avoid stress caused by high inrush currents during the turn on phase. The unit powers up in a defined sequence, and during warm-up the output of the HP 300 MKII is shorted to ground. The same occurs when the unit is switched off. This avoids unwanted signals being passed to the power amplifier. The lifetime of the tubes are extended considerably while their sound quality remains stable for many years due to this protective measure.

Optional Phono Stage

The optional internal Phono Stage of the HP 300 MKII is normally set for MC (moving coil) cartridges. The gain of the MC phono board is internally adjustable in two steps. A second selector activates the subsonic filter. Listening to older analogue records is recommended with a subsonic filter to avoid infrasonic signals.

Frequency Response:

Frequency Response accuracy of line-stages in "low gain" setting 20 Hz - 200 kHz: 0,1 dB

Total Harmonic Distortion:

Total Harmonic Distortion (THD + noise) of Line-Stage between 20 Hz and 200 kHz.  The distortions remains low up to 20 kHz.

Interfering Signal Spectrum:

Interfering Signal Spectrum of Line-Stage 5 V Output Voltage @ 1 kHz. The low level of hamonic distortion and low noise level are clearly visible.There are no hum components @ 50 Hz and 100 Hz.

Phono RIAA:

Frequency Response of Phono-Stage with and without Subsonic-Filter