Octave HP 700 SE Tube Preamplifier with Phono RIAA and IN 6 Module Black

HP 700 SE tube preamplifier supplied with the optional Phono RIAA board and the IN 6 RCA MC transformer input module.

The HP 700 SE is a tube preamplifier that features innovative precision technology as well as sonic refinements to the output stage. Like its predecessor, the HP 700, it meets the listener's individual wishes for their high-end combination thanks to its modular freedom. The new SE version now has two parallel XLR sockets next to the two RCA outputs on the back, allowing all variants of bi-amping. But even more important are the modifications to the actual Class A output stage.

Refined tube technology and intelligent modular technology made the HP 700 future-proof right from the start - an innovation in the market. Now it was time to push the innovative HP 700 even further in terms of sound and technology. The new HP 700 SE is a tube preamplifier that features both new precision technology and tonal refinements of the output stage. Like its predecessor, its modular freedom meets the listener's individual demand for truly customized high-end setup. Instead of being bound by the fixed audio and technical parameters of the equipment, listeners can adapt the technology of the HP 700 SE to their individual requirements and preferences.

In the new SE version, there are now two parallel XLR sockets next to the two RCA outputs on the back panel, allowing all types of bi-amping. But the modifications of the actual Class-A-output stage are even more important. The search for the even finer sound took place with the help of extremely time-consuming and complex measurements, along with accompanying listening sessions. These difficult adjustments are responsible for the tonal improvements, especially the mid-tone of the pre-amplifier. The tube configuration remains unchanged compared to the predecessor HP 700, as do all the other tried-and-tested technical refinements on this incomparable preamp:

Precision Technology In The Line Stage

The term "precision technology" stands for a circuit in tube technology that has an extreme bandwidth up to 1 MHz, an impressively low output resistance of 100 ohms and sensationally low distortion of 0.001 %. Three amplification settings, combined with selectable output impedance, enable perfect fine-tuning of the HP 700 SE to the characteristics of the sound reproduction chain. The three-stage amplification settings allow optimal matching of the volume control to the efficiency of the speaker.

PSU Technology

In combination with the newly developed, high-precision, low-noise supply-voltage stabilizing circuitry, the separate, magnetically shielded, outboard power supply of the HP 700 SE (essential for the low-noise and low-hum function of the MC-input) ensures constancy of the audio output even when the mains voltage is subject to wide fluctuations and high interference levels. Added to this, the integrated control logic system guarantees maximum operational reliability and, backed by our exclusive soft-start technologies, ensures the tubes and the unit have a life of up to twenty years.

Bypass

The multi-channel bypass function allows the HP 700 SE to be integrated into an existing home-theater system. The logic-controlled input selector circuitry enables activation of the bypass function for an XLR or RCA input on the preamp's rear panel. The Home Cinema signal is present at all three outputs.

Additional Individualization Options: Modular Inputs

The connection possibilities of the generously configured standard HP 700 SE model are rounded off by two user-selectable, optional input modules. An optimized input module can be used for unique applications, for anything from an MC step-up transformer to a transformer-based XLR input module. The plug and play modules can be readily installed or upgraded at any time. PHONO Innovative technology has also been applied in the redesign of the Phono RIAA amplifier. The further development of the RIAA stage has improved the signal/noise ratio, while simultaneously reducing system-related distortion. The widening of the bandwidth enables accurate RIAA equalization and exploits the full potential of analog reproduction. The wide variety of optional input modules ensures that the optimal input can be installed for any cartridge.

Tone Control

Precison Tone Control

Another innovation, the optional tone control, rounds off the HP 700 SE modularity. The valve-based, precision tone control unit guarantees consistency of the sound, even at low volume. Precise adjustment of bass and treble, with a 0.3 dB channel separation, allows the tone to be adjusted without impairing the spatial reproduction.

Balance Control

The frequency-compensated balance control allows channel-separated volume adjustment in 1 dB steps. This technology eliminates any controller-related sound shifts. Using 12-position stepped switches, the setting is long-time stable, with 100 % repeatability.

Output Selector Switch

The HP 700 SE output can be switched to multiple zones by manual activation of the outputs. Whether the output is through XLR, RCA or all three outputs simultaneously, a total of three output stages can be utilized for separate rooms, different speakers or bi and tri-amping.

Stepped Volume Control

The optional, frequency-compensated, 47-position stepped switch ends the debate about the influence of the controller on the quality of the music signal. At 0.1 dB, the channel deviation is supreme. Our own in-house development, the volume control design constantly maintains the frequency bandwidth throughout the entire control range, reducing controller-related distortion to a barely measurable level. However, as a result of the mechanical design of the stepped attenuator, the switch positions cannot be controlled via the remote control.

Options HP 700 SE: Phono RIAA, modular inputs for phono and high level, level switch for volume, control unit see below.

Of course, the HP 700 SE has power management with soft start electronics, gain selector, monitor/record output and the HT bypass.

General Facts

• Basic model: HP 700 SE Line
• Options: Phono RIAA unit, 8 input modules, 47-pin step switch for volume, control unit
• Design: Silver or Black
• Tube complement: Line: ECC82, 2 x EF800; Phono: ECC83, ECC81, ECC88; Control modul: ECC88
• Inputs: 3 x RCA, 2 x XLR, 2 x free selectable, 1 x Bypass RCA
• Outputs: 2 x RCA, 1 x XLR, 1 x monitor / tape record (RCA)
• Dimensions Preamplifier / Power Supply: 462 x 130 x 480 mm / 110 x 90 x 277 mm (W x H x D)
• Weight Preamplifier / Power Supply: 10.0 kg / 3.8 kg

Features

• External power supply
• Soft start control electronics: Providing maximum tube life and trouble-free switching on and off
• 3 levels of amplification can be selected: Adaptation to the efficiency of the speaker
• XLR outputs with transformers: Prevent hum disturbances
• Freely selectable inputs: By modular technology
• Option Control Modul: Tone and balance control, output selector switch
• HT Bypass (optional): Bypass-function for multichannel/home cinema
• Two parallel XLR outputs: for Bi-Amping

Specifications

• Gain factor: High: 25 dB = 18.5 / Med: 18 dB = 7.8 / Low: 12 dB = 4
• Frequency response: High: 10 Hz - 200 kHz -0.7 dB / Med: 10 Hz - 200 kHz -0.3 dB / Low: 10 Hz - 200 kHz -0.2 dB
• Total harmonic distortion: 0.01% at 3V on 10 kOhm
• Signal-to-noise ratio: High: -98 dB / 38 µV; Med: -104 dB / 18 µV; Low: -110 dB / 8 µV

Phono RIAA

The further development of the RIAA stage of the HP 700 (SE) increases the signal-to-noise ratio while reducing system-related equalization errors. Increasing the bandwidth enables precise RIAA equalization and explores the full potential of analog playback. The Phono RIAA is equipped with a switchable subsonic filter.

The principle of the record is based on mechanical scanning: music signals are cut into the record as an audio track and mechanically sampled by the pickup. In order to be able to integrate the entire frequency range from 20 Hz to 20 kHz into a sound track, low frequencies must be reduced and the upper frequency range must be increased. The ratio of boost or cut is defined and is referred to as RIAA equalization.

A phono amplifier must therefore be able to reproduce the RIAA equalization exactly in order to avoid tonal distortions. An accuracy of 0.5 dB across the entire frequency range and channel equality of 0.1 dB are minimum requirements.

We realized the phono RIAA circuit of the HP 700 SE with three tubes:

ECC 83 (12 AX 7)

ECC 81 (12 AT 7)

ECC 88 (6922, 6DJ 8)

The phono RIAA amplifier of the HP 700 SE must always be supplemented with an input module. A maximum of two phono input modules can be installed. The function of the input modules corresponds to an input amplifier, which raises the different signals from the pickup to a constantly high level that the RIAA amplifier can optimally process. Phono is then selected via IN 1 to IN 2.

Subsonic filters

In addition, the Phono RIAA is equipped with a switchable subsonic filter (-3 dB at 15 Hz).

Wavy records and unfavorable pickup/tonearm combinations can lead to significant low-frequency interference that affects bass reproduction. These low-frequency levels can be attenuated with the switchable subsonic filter. The corner frequency is outside the audible range at 15 Hz.

Delivery condition: Subsonic filter on

IN 6: RCA MC transformer input module

IN 6 is a step up transformer for low-resistance MC systems. The transmission factor can be switched between 15 and 30. The Gain 30 position is ideal for classic low output MC systems with a level of around 300 µV, the Gain 15 position is optimally tuned for all modern MC systems that deliver a level between 0.5 and 1 mV.

Specifications

• Input sensitivity Gain 15 / 30: 0.2 - 2 mV / 0.2 - 1 mV
• Input impedance Gain 15 / 30: < 320 Ohm / < 80 Ohm | 30 Hz - 40 kHz
• Gain factor: 15 / 30
• Pickup internal resistance Gain 15 / 30: 5 - 25 Ohm / 0.5 - 5 Ohm