HP 300 SE

The HP 300 SE preamplifier is a further development of the legendary HP 300 MK2. It expands the Octave preamplifier range primarily through the large variety of connections. The HP 300 SE also offers outstanding sound quality thanks to improvements in the power supply and the output stage of the line amplifier. The newly developed line stage has an extremely high signal-to-noise ratio.


Available Colors: Silver or Black


The OCTAVE HP 300 SE is a further development of the HP 300 MK2, whose ancestor HP 300 in turn benefited from the technical development of the reference Jubilee Preamp. The HP 300 SE goes beyond the HP300 MK2 in many ways. The most important are an external power supply with significantly advanced power supply technology, improved amplifier circuitry, amplification in 3 gain stages, XLR out with transformers and improved housing optics. The further development of the HP 300 into the HP 300 SE closes the gap to high-priced precursors. The sophisticated technology and the use of specialized output transformers in the XLR output make it an audiophile treat.

The power supply of the HP 300 SE consists of the external mains transformer with optimized mains filter characteristics and precise, extremely low-noise voltage regulators in the preamplifier. Both systems are perfectly coordinated and audibly reduce the noise and interference levels of the HP 300 SE. The balanced output is constructed with a precision balancing transformer. This transformer makes it possible to switch the ground connection to the power amplifiers on or off. This feature is helpful to prevent leakage current from the ground connection of the connected devices. Noise is caused not only by the specific properties of the tubes, but also by impurities in the network or interference within the power supply. In principle, these mains leakage currents are always present and have a negative influence on the sound. This is history with the HP 300 SE.

The OCTAVE HP 300 SE is a real all-rounder. It has two independent XLR inputs, three RCA inputs, a monitor output, two RCA outputs and one XLR output. The equipment is rounded off by a monitor output, which can be used for a headphone amplifier or any recording device, or the A/D input of a PC. The HP 300 SE optionally offers a phono MC input with a variety of setting options.

The gain can be selected in three levels, which allows the overall gain to be optimally adjusted to the efficiency of the speakers. Both outputs, XLR and RCA, have a very low output resistance. This means that cable lengths of up to 10m to the power amplifier have no negative influence. A helpful feature in modern systems is the multi-channel bypass (home theater function). The HP 300 SE also offers the option of selecting the bypass function for an RCA or XLR input.

Of course, the HP 300 SE has power management with soft start electronics, gain selector, monitor/record output and the HT bypass. (See technology for description)

General facts

Basic model HP 300 SE Line
Options Phono MC or MM
Design Silver or Black
Tube complement Line: ECC81, ECC88; Phono: ECC81
Inputs 3 x RCA (one is phono with the option phono otherwise it is a line level input) / 2 x XLR
Outputs 2 x RCA, 1 x XLR, 1 x Monitor (RCA)
Dimensions Preamp / Power Supply 438 x 78 x 390 mm / 110 x 77 x 277 mm (W x H x D)
Weight Preamp / Power Supply 9.0 kg / 3.0 kg


External power supply
Protection system Protection circuit for device and tubes
Amplification selectable in 3 levels Adaptation to the efficiency of the speaker
HT Bypass Bypass mode for multi-channel receiver / TV


Gain factor High: 25 dB = 18.5 / Med: 19 dB = 8.8 / Low: 12 dB = 4
Frequency Response High: 10 Hz - 200 kHz -0.1 dB; Med: 10 Hz - 200 kHz -0.25 dB; Low: 10 Hz - 200 kHz -1,5 dB
Total harmonic distortion Low | Med | High 0.005% | 0.007% | 0.03% at 3V / 7.5 kOhm
Signal-to-noise ratio High: -92 dB; Med: -100 dB; Low: -108 dB


HP 300 SE Review 09/2018 - German version

"A dream of a preamplifier. Anyone who can do without the modular design of the HP 700 will hardly be worse off in terms of sound without really having to miss out on any of the features. The highest level of sound and workmanship."

Germany - STEREO - September 2018

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HP 300 SE Review 06/2016 - German version

"Are you looking for a really "cool" and multifunctional tube preamplifier made in Germany? Here you go - here is the Octave HP 300 SE."

Germany - HiFi-Stars - Alexander Aschenbrunner - June 2016

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HP 300 SE Review 04/2014 - German version

"It can practically do everything between gentle, silky and aggressive, never seems too comfortable or even sluggish, let alone spongy, but can also claim a beneficial, small touch of warmth. This coordination is undoubtedly skilful and also has a lot of addictive potential - also through driving rhythm - and if required, even calm and elegance directed towards the listener."

Germany - stereoplay - Roland Kraft - April 2014

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