T+A A 3000 HV Power Amplifier
The Power Amplifier
The A 3000 HV is the ideal power amplifier and complement to the P 3000 HV pre-amplifier. It is designed as a stereo power amplifier, but can also be configured to work in mono mode, in which guise it is capable of delivering twice the current and in which it doubles the pure Class-A mode. Thanks to HV technology, this powerhouse offers superb sound characteristics as well as incredible power and performance: a standard which is unsurpassed even by much more expensive amplifiers. The principle of splitting a High-End system into separate pre-amplifier and power amplifier gave our development team the opportunity to implement the finest possible circuit designs and technologies without having to take into account space considerations and case restrictions. This applies both to the electronic components and the mechanical design of the case, since – if the aim is to attain the best possible sound – a preamplifier’s requirements are fundamentally different from those of an power amplifier: preamplifiers process relatively small signals, and the crucial aspect of their design is the avoidance of induced and other interference; power amplifier, on the other hand, have to cope with relatively large signals, and the stability of the power supply, its current delivery capacity and performance independent of load are much more important.
The entire electronic power circuit with output stages and mains power supply is housed in its own shielded compartment in the underside of the machine. The dividing wall between top and bottom sections is 10 mm thick and – of course – is also made of aluminium. Voltage amplification and current amplification circuitry is housed on separate circuit boards in separate case sections, in order to prevent mutual interaction. The sophistication of the design does not stop there, as we have even provided galvanic separation between the two. Thanks to this uncompromising design philosophy there is absolutely no feedback of the loudspeaker currents into the voltage amplifier stages, and complete freedom from loudspeaker loading effects. The voltage amplifier is an extremely linear, broad-band, cross-coupled differential cascode amplifier, followed by a single-ended Class A large signal stage which provides superb sound quality.
The fully symmetrical current amplifier stage (output stage) is fitted with MOSFET drivers and the latest “thermal tracking” bi-polar output transistors; this combination delivers a very harmonious audiophile sound image combined with tremendous current delivery capacity. The output stage transistors feature integral temperature monitor diodes which we use to maintain the power transistors at an absolutely constant operating point, regardless of temperature, allowing us to control the circuit’s distortion behaviour perfectly, regardless of the momentary load. By maintaining full symmetry in the arrangement of all conductors in the output stages, speaker cables and mains power supply we have succeeded in providing complete compensation for all signal currents. The net result is a complete lack of magnetic stray fields, and no electromagnetic feedback into the input stages.
The enormous power of the power amplifier calls for particularly high-quality, stable loudspeaker terminals; they are machined from solid pure brass and rhodium-plated on every surface. Rhodium is the perfect contact material: as conductive as silver, as durable as platinum, as corrosion-resistant as gold (and unfortunately as expensive as all three put together).
For the most exacting requirements a further option exists for improving the quality of the voltage and current supply: this is the PS 3000 HV supplementary mains unit.