Class-A. A circuit concept that has bewitching midrange in both push-pull and single-ended amplifiers due to the low distortion. But unfortunately it is paired with low power, dynamics and excessive heating of the amplifier. Features that do not match the product profile of our popular integrated amplifiers 100%. It was therefore important to develop a concept that would bring the undisputed tonal advantages of this principle to life.
In short, a “Class A concept” technically means a higher quiescent current setting and therefore less distortion (almost only second-order harmonics, referred to as k2), but also a limited full modulation with less power. Push-pull concepts, on the other hand, can deliver 4-16 times the output power compared to Class-A, but lack with inharmonic distortions (i.e. odd harmonics k3 and k5). Two soundscapes with followers on both sides. Of course, Andreas Hofmann was tempted to combine both concepts into something new.
After extensive development, a new amplifier concept was created:
The V 70 Class A, a Class A push-pull amplifier in a pentode circuit.
For this, a new Class A technology had to be developed:
The Dynamic Bias Control
Dynamic Bias Control means that Andreas Hofmann has found ways to dynamically shift the limited dynamic range, and thus the limited power of the Class A concept, according to the requirements. The development of the dynamic operating point setting enabled a self-regulating Class A amplifier with approximately twice the output power of 50 W RMS with up to 70 W (with Super Black Box) peak power.
This technology combines the tonal purity of Class A with the dynamics and performance of push-pull A / B technology.
The modern concept of a Class-A push-pull amplifier in a pentode circuit makes it possible to guarantee the Class-A virtues over the entire frequency response up to maximum modulation. The enormous power, with up to 70 watts peak power, is significantly above the performance level of conventional Class A amplifiers and is more than sufficient for most speakers.
The integrated amplifier is equipped with a balanced input as standard. If a turntable is connected, the optional phono board (either MC or MM) offers the right solution.
In the case of the V 70 Class A, an auto-bias circuit is used. The amplifier adjusts itself to the tube used and does not require any adjustment controls. The proven BIAS measurement with the colored LEDs is still available, however, only to check that the four output tubes are working properly.
Similar to the other top models from Octave, the V 70 Class A also has the power preselection, Power High and Low, so that the device can be optimally adapted to different power tubes. Due to the high power in Class A operation, a KT 120 or KT 150 tube must be used for Power High. Less powerful KT88 or 6550 types should be operated at Power Low. Around 15 W Class A and 25 W music power are still available.
Octave typical measures, such as the Power Management with electronic monitoring are integrated as well as the Protection System, ECO Mode, the Home Theater Bypass circuit, the Power Selector, a (Super) Black Box Connection and the useful Regulated Preamp Output (for direct connection of a subwoofer).
Our special Power Supply Technology protects the amplifier against various types of mains interference. Mains fluctuations and high-frequency mains disturbances do not cause any sonic deterioration.
With the V 70 Class A we have the line of the legendary powerful Octave integrated amplifiers extended by a highly musical Class A concept.
| Basic Model | V 70 Class A Line |
| Options | Phono MC or MM |
| Design | Silver or Black |
| Tube Configuration | 4 x KT 88-S4A-Carbon, optional 4 x KT 120 TS |
| Inputs | 5 x line level RCA (one is a bypass input and one is a phono input with the phono option) / 1 x XLR |
| Outputs | 1 x pre-out regulated / 1 x record output RCA / 1 x loudspeaker output |
| Dimensions | 451 x 150 x 415 mm (W x H x D) |
| Weight | 22.1 kg |
| Full metal remote control | Volume control |
| Eco Mode | Power saving mode |
| Bias Control | Quiescent current display and setting |
| Adjustable Pre-Out | Preamp output RCA |
| HT Bypass | Bypass-function for multichannel receiver / TV |
| Protection system | Soft Start; Protection circuit for amplifier and output tubes |
| Power selection | Adaptation to alternative output tubes |
| Output Power | High: 2 x 50 W / 4 ohms; Low: 2 x 25 W / 4 ohms |
| Frequency response | 20 Hz – 70 kHz @ 50 W - 1 / - 3 dB |
| Total harmonic distortion | 0.1% at 10 W / 4 ohms |
| Signal-to-noise ratio | - 100 dB / 50 W unrated |
"I would say that Andreas achieved what he set out to do: create an amplifier with the soul of a class-A combined with the muscle of high-powered AB. The result is a product like nothing I've heard before, which sounded bigger than life and natural simultaneously. The Octave V 70 had the spirit of cinema vérité in Technicolor. All things considered, I think the $15,900 asking price for the V 70 with the KT120 tubes and the Super Black Box is a pretty good deal."
United States of America - stereophile - Robert Schryer - May 2024
“Ultimately and above all, the Octave V70 Class A is an excellent, natural-sounding tube integrated amplifier that undoubtedly occupies a special position in its class and also keeps the audiophile’s instinct to play alive with a variety of options for trying out and sound tuning…”
Germany - LowBeats - January 2024
"After he had cultivated and further perfected the push-pull or push-pull method with one or more tubes for the negative and positive half-wave over many years and models, this leap over his own shadow - along with the outstanding sound results - was the trigger to also dedicate ourselves to Class A technology."
Germany - AUDIO - November 2020
"If deep synthetic bass is pushed into the room after around nine minutes, it's not just diaphragm shocking sounds. The entire event is living, breathing; The attack and release processes are depicted very accurately, yet realistically and sensitively."
Germany - STEREO - October 2020
"A test report with remarkable musical facets."
Germany - image hifi - October 2020
