Preamplifiers

The Octave HP 700 preamplifier looks back to a long and successful history, the origins of its basic circuitry are derived from the classic HP 500 model, first presented in 1986. This concept has been consistently developed over 30 years and attracted worldwide attention.

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 o 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.

Specifications

Inputs	3 x RCA, 2 x XLR, 2 x arbitrary 1 x Bypass RCA (can be switched to IN4 -XLR)
Outputs	2 x RCA, 2 x XLR, 1 x Monitor / Tape Record (RCA)
XLR transmission ratio	0 dB
XLR pin assignment	1 = ground, 2 = positive, 3 = negative
Line stage
Output resistance	100 / 300 ohms RCA; 150 ohm XLR
Monitor Out output resistance	240 ohms
Maximum output voltage	12V
Gain factor Gain High	25 dB = 18,5
Gain factor Gain Med	18 dB = 7,8
Gain factor Gain Low	12 dB = 4
Signal-to-noise ratio Gain High	- 98 dB / 38 µV at 3 V output voltage
Signal-to-noise ratio Gain Med	- 104 dB / 18µV at 3 V output voltage
Signal-to-noise ratio Gain Low	- 110 dB / 8 µV at 3 V output voltage
Equivalent noise-level	14 nV √Hz
Frequency response Gain High-RCA	10 Hz – 200 kHz  -0,7 dB, 0,7 Mhz -6 dB
Frequency response Gain Med-RCA	10 Hz – 200 kHz  -0,3 dB, 1.3 MHz -6 dB
Frequency response Gain Low-RCA	10 Hz – 200 kHz  -0,2 dB, 2,1 MHz -6 dB
Frequency response XLR	10 Hz – 200 kHz  -1,5 dB
Ramp-up time Gain Low	250 ns
Ramp-up time Gain Low	60 V/µs
Total harmonic distortion, Gain Low, Med, High	0.01% at 3V on 10 kOhm
Channel separation	-90 dB / 1 kHz, Input short-circuited
Crosstalk between inputs	- 80 dB / RCA, -95 dB XLR / 1kHz
Input resistance	50 kOhm
Channel matching via volume control	0,5 dB - 70 dB
Phono
RIAA equalization tolerance	0,3 dB / 15 Hz - 20 kHz
Corner frequency - subsonic filter	15 Hz / - 3 dB
Signal-to-noise ratio	- 75 / - 84 dB / with IN 2 MC Input
Input sensitivity	250 µV / 600 µV / with IN 2 MC Input
Gain MC Gain Low - Pre Out	Gain Low: 70 dB, Med: 77 dB, High: 83 dB
Gain MC Gain High- Pre Out	Gain Low: 79 dB, Med: 86 dB, High: 92 dB
General Facts
Power consumption	35 - 60 W
Weight preamplifier	10 kg
Weight power supply	3,8 kg
Supplied accessories	Power calbe, remote control
Dimensions of preamplifier (over-all)	462 x 130 x 480 mm (W x H x D)
Dimensions of power supply (over-all)	110 x 90 x 277 mm (W x H x D)
Dimensions (in mm)

• The HP 700 SE is equipped with two RCA and XLR outputs.
• The XLR output is transformer balanced and galvanically isolated.
• Soft start for heating, power supply and signal output; providing maximum tube life and trouble-free switching on and off.
• The gain of the Line-stage can be switched in three levels.
• External power supply with multiple shielded power transformer and integrated mains filter.

Frequency response:

Line stage hum and noise level:

FFT interference spectrum:

Phono frequency response with and without subsonic filter:

Control characteristics of the tone control:

Control range and balance control frequency response: