Our perennial preamplifier, the HP 500, has been around for almost as long as OCTAVE and was in many ways responsible for defining our approach to building amplifiers. For over 20 years, this preamplifier has been the epitome for consistent excellence in sound quality and state-of-the-art tube technology.During this time, it has maintained its market-leading position thanks to regular design updates from OCTAVE.
OCTAVE recently developed the SE (Special Edition) version to mark the 25th anniversary of Stereoplay magazine, which first tested the original HP 500 in 1989. The SE brings the HP 500 preamp back to the current state-of-the-art once more. The use of two Siemens D3A (EF 184) pentodes provides the output stage of the HP 500 SE with a significantly greater bandwidth (0.2 Hz to 2.3 MHz, 6 dB).
The extremely low cut-off frequency is responsible for the clearer and more tightly defined bass, which provides the foundation for a clean low frequency register and a thrilling midrange performance. OCTAVE has also further refined the outboard power supply. MOSFET transistors regulate the high-voltage supply. Increased reservoir capacity, improved rectification with Schottky diodes, and end-to-end electronic stabilization all ensure a virtually noise-free supply voltage with a noise component of less than 300 µV. These measures contribute to the exceptionally high signal-to-noise ratio of 103dB.
HP 500 SE Line, optional with Phono MM/MC
Limited Edition to 100 pieces
Input-Stage: 1 x ECC 82; Output-Stage: 2 x EF 184 (Siemens D 3A)
The HP 500 SE features a total of six single-ended (RCA) inputs. Outputs included are one RCA Record output, two pair of RCA and one pair of balanced (XLR) outputs. The balanced (XLR) output is transformer coupled to provide ground isolation and perfectly phase-inverted signals with no group delay.
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 500 SE 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 always includes two independent inputs: one for MM (moving magnet) and one for MC (moving coil) cartridges. The selector for the inputs is in the rear front. A second selector activates the subsonic filter. Listening to older analogue records is recommended with a subsonic filter to avoid infrasonic signals.
The Input Impedance of the MM input is 47 k Ohm; the MC Input is adjustable between 37 to 500 Ohms. Gain of the MC Section is 80dB.
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 from Line-Stage by 5 V Output Voltage and 1 kHz. Clearly recognizable dropout from harmonics and the extrem low Noise. No ripple remains on 50/100 Hz.
Frequency Response of Phono-Stage with and without Subsonic-Filter