Nothing sounds better than the original

The goal of every high-end device should be the most lifelike reproduction possible. However, especially in the power amplifier sector, this goal is difficult to achieve with classic tube technology. Modern high-resolution speakers require stable, broadband power amplifiers. Tube power amplifiers using classic technology are often overwhelmed here. The sonic result in the areas of dynamics, bass, natural fidelity and load stability falls short of expectations. The analysis of these properties led us to throw some essential components of classic tube amplifier technology overboard and replace them with new, modern circuits.

It makes no sense to optimize a system that is inherently limited - the limitation itself must be eliminated. This insight led to our complex amplifier technology. Depending on the task, Octave uses both tubes and modern semiconductor circuits. In this way, the strengths of the respective technology are used, which leads to the multiplication of the positive properties.

Technical features

Amplifier concept

The properties of broadband, low level of distortion, stability compared to the impedance of difficult loudspeakers, linear modulation behavior (= dynamics) can be achieved with our power amplifier design. The power supply with zero impedance technology ensures the necessary bandwidth, especially in the low frequencies.

In our opinion, control and stability of the amplifier is not ensured by an extremely high damping factor (with a correspondingly high negative feedback), rather the optimization of the negative feedback itself is a prerequisite for a stable power amplifier. If stability is present, the necessary control is also present.

Power supply technology

The power supply is very important in terms of the sound itself and especially in terms of the dynamics and power delivery of the power amplifier. Octave power supplies are very efficient, extremely low in noise, hum and distortion and basically only contain the best available electrolytic and film capacitors for energy storage. Due to the special requirements of the tubes, Power Management (PM) is the controlling element of the power supply.

Power Management

The power management controls and regulates the timing of the functions: heating - operating voltage - monitoring of relevant safety functions.

Only after stabilization of all parameters necessary for the operation of the tubes does the PM release the signal path. This prevents unfavorable conditions that are harmful to the tubes when switching on and off and also during operation. The PM also has an electronic fuse integrated.

Service and lifespan:

In keeping with the motto "The best car is worthless if it doesn't run", we have given our devices all of these features so that everyday use is as easy as possible.
The power management with all its functions ensures that the devices have an unusually long service life. While the (final) tube lifespan is around 3 - 5 years, the devices themselves achieve a lifespan of around 10 - 20 years without the need for further service, so that they can be described as "life companions".

One-off production

OCTAVE devices are manufactured and checked individually. Development and design were penned by Andreas Hofmann. The company has a dedicated transformer winding shop where all transformers and transformers are custom-made. Basically, the output transformers are of utmost importance. We develop and optimize these specifically for each device.

Made in Germany

OCTAVE devices are 100% made in Germany. Our workforce is highly qualified and motivated. Many of our employees have been with us for decades and have developed into specialists in their field. As a regionally based company, we train ourselves in the areas of industrial clerk and electronics technician for devices and systems. We work with highly specialized suppliers from our area. The mechanics are manufactured throughout on modern CNC machines.

Device-specific technical features

Additional soft start function (all amplifiers)

The soft start function with integrated inrush current limitation enables the device to be started in a way that is gentle on the tubes and components. Soft start, the time-delayed, gentle ramp-up of the heating and operating voltage, is extremely important for the lifespan and sound stability of the tubes. The “intelligent” inrush current limitation reduces the stress caused by repeated switching on and off. The soft start switching processes no longer have any significant influence on the lifetime of the device.

Gain Selector (preamps)

The gain selector can be used to set the gain of the preamplifiers to Low, (Med) and High. It can happen that, depending on the sensitivity of the power amplifier or the efficiency of the loudspeaker, together with the sometimes quite high output voltage of a source, the volume control takes place in an unfavorable range. In this case you can e.g. B. reach an increased listening level after just a few millimeters on the volume knob. The different amplification factors then offer the possibility of a practical adjustment.

Monitor / record output (preamp and integrated amplifier)

Some of our models (V 80 SE, Jubilee Preamp) have a classic tape - record "back tape" circuit for making and listening to recordings using an analog or digital medium. The other models have a monitor output for recording/storing the music signal.

Home cinema bypass (preamplifier and integrated amplifier)

The bypass home cinema function is intended for when the 2-channel combination is to be integrated into a multi-channel system/TV. In this position the volume control is bypassed. This setting or this input is intended for multi-channel applications with control of the overall volume on the multi-channel receiver (multi-channel / home theater / TV). The home cinema bypass function is available in both the integrated amplifiers and the preamplifiers.

Pre-Out - regulated preamp output (integrated amplifier)

The regulated preamp output on our integrated amplifiers is usually required for an active subwoofer. The pre-out is decoupled via a separate buffer to eliminate influences from the subwoofer on the integrated amplifier. The input resistance of the subwoofer is therefore not critical.

Electronic protection (protection system) (integrated amplifier, power amplifiers)

The electronic fuse constantly monitors the power amplifier and other important parts of the device. In the event of an error, the power supply within the device is immediately switched off. This means that consequential damage inside and outside the device is almost impossible in all scenarios that occur. The electronic fuse detects tube damage, overloading of the power amplifier, short circuit of the speakers and other malfunctions.

ECO mode (integrated amplifier, power amplifiers)

Ecomode is an energy-saving and safety function that automatically switches off the tube section of the device after approx. 7-10 minutes during breaks in operation without a music signal. The power consumption in ECO mode drops to approx. 15% of normal. When a signal arrives at the amplifier again, the device boots up again and is ready to play again after a minute. Attention: Ecomode is not a standby circuit. Parts of the device remain active, e.g. B. to make recordings of a source.

Bias setting and display (integrated amplifier, power amplifiers)

The BIAS (quiescent current) of the output tubes can be checked and corrected by the user at any time using the integrated measuring system. This is not only important for ongoing operation: the BIAS setting can ensure that the tubes always work at their optimal level. This means that the tonal properties of both stereo channels are always the same and there are no level differences between right and left.

Power selector (integrated amplifier, power amplifiers)

With the power selector you can set the amplifier to different types of output tubes. Depending on the tube type and the position of the power selector, more or less output power can be achieved. Power selector in HIGH position: This position is intended for the powerful KT 120 and KT 150 tubes. These tubes can of course also be operated in power low if less power is desired. The LOW position is intended for types KT 88 and 6550. These tubes should not be operated at power high.

Black box connection (integrated amplifier, power amplifiers)

Like the Black Box, the Super Black Box is an external, passive power supply amplifier for the integrated amplifiers and power amplifiers. The Super Back Box, however, with even greater capacity. The black boxes primarily increase the storage capacity of the power amplifiers' power supply. The pulse power of the power amplifiers is therefore significantly higher. However, this is not the primary effect. The biggest gain is that the power amplifiers become significantly more load-independent.
The resolution and fine detail increase. An unusual contour and definition is achieved, especially in the fundamental tone. The entire vocal range is purified and gains in spatial extent and localization. The black boxes enable adaptation to the respective loudspeaker. The amplifier “grows” with the speaker. As a rule, it can be said: the more sound reserves there are in the loudspeaker or in the chain, the more optimization is possible.

Zero Feedback (Jubilee Preamp and Jubilee 300 B)

Explanation for specialists: Advantages and disadvantages of negative feedback and zero feedback

Negative feedback:

In amplifiers, negative feedback is a circuit in which the output signal is compared with the input signal. If the output deviates from the input, a correction signal is generated that is intended to correct an “error”. The error increases due to the load on the amplifier caused by the cable and the connected power amplifier or loudspeaker.

However, an amplifier naturally always has a minimally short transit time from the input to the output, which leads to a timing error, since the signal at the output is already a thing of the past compared to the input of the amplifier. The timing error therefore limits the negative feedback in the upper frequency range of the amplifier. Ideally, negative feedback only makes sense if the amplifier is very, very fast, i.e. H. has a bandwidth up to the megahertz range. This is the case with the HP 300 SE and the HP 700 SE.

Zero Feedback

In amplifiers without negative feedback, the output signal is not fed back for error correction. The high-frequency reproduction is no longer dependent on the runtime error. The characteristics of this concept are constant from the bass to the upper cutoff frequency. However, this variant places very high demands on the linearity and low distortion of the circuit. The output stage of a zero feedback amplifier must be very stable and immune to the load. The power supply must also generate perfect conditions, as disruptions in the power supply are no longer compensated for. Amplifiers without feedback therefore always require significantly more effort in all areas of design.

Headphone output (V 16 Single Ended, V 80 SE)

Very high demands are placed on a headphone output because headphones naturally have a very high level of efficiency. This requires a headphone amplifier with an extremely low noise and hum level, which should be approximately 10x lower than a power amplifier for loudspeaker operation. The impedance of headphones is in the range 20 – 600 ohms. This bandwidth is very large and cannot easily be optimally controlled with just one headphone amplifier. We therefore developed a separate headphone amplifier for the V 80 SE that achieves the best results for headphones with an impedance of 150 ohms or more. An optimized output has been integrated into the V 16 Single Ended for uncompromising high-end headphones that have an impedance of 20 - 100 ohms. Small single-ended power amplifiers with a maximum of 8 W are ideal for this application. However, reducing the noise and hum level of the single ended power amplifier to the desired low level was only possible with very complex measures. The V 16 Single Ended is probably one of the few single-ended amplifiers on the world market optimized for headphones.


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