V 70 CLASS A
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.
Description
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.
OPTIONS
Super Black Box
The Super Black Box is a passive power supply extension designed for all Octave integrated and power amplifiers. Due to the massively increased storage capacity of the power supply the pulse power of the power amplifiers is significantly increased. What is also very important is the increased independence from the electrical load – the loudspeaker. A big sonic benefit not just for sophisticated speakers.
Black Box
The Black Box is a smaller version of the Super Black Box with the same concept. It contains a circuit with electrolytic capacitors that increases the internal power supply of the amplifier and stabilizes it against mains fluctuations. Low-frequency network interference is perfectly suppressed. The black box has its own housing and is permanently connected to the amplifier using a special high-current connector.
Phono MM oder MC
There are two phono boards to choose from an MC or MM board. The additional board is internally connected to the phono input which is then no longer available as a high level input.
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