The Integrated Amplifier

The PA 3100 HV is a further development of the PA 3000 HV, and most of its sub-assemblies are identical. The immediately obvious difference is the pair of VU meters in the front panel, which display the power generated per channel in logarithmic form in Watts into 4 Ohms. A revision of the pre-amplifier section (D.C. coupling) has brought an additional improvement in sound quality.
A further development is the redesigned analogue mains section and voltage power supply, which is similar to that of the A 3000 HV. This makes it possible to connect the supplementary PS 3000 HV mains section in order to gain a further increase in stability and performance of the power supply system as a whole. The additional unit provides an extra 1800 Watt of supply power, enabling the system to control even the most difficult loudspeakers without effort, so that they can unfold the best possible sound quality.

Circuit Topology

As with the P 3000 HV, the circuit topology is based on a differential cascode amplifier with individually selected audio J-FET transistors, and stages of completely discrete construction without op-amps (operational amplifiers). Virtually no overall negative feedback is required due to this circuit arrangement and the quality of the components employed. The high operating voltage of HV technology is the key to excellent linearity combined with extremely wide dynamic range: signals up to 60 Vss can be processed without distortion.
In the HV series the signal switching and adjusting functions are carried out by encapsulated gas-tight gold-contact relays, which are totally immune to contact problems due to corrosion, dust, etc., and do not suffer from ageing effects even after many years of operation. The pre-amplifier even employs bi-stable relays, which require no permanent coil current, and this in turn eliminates any adverse inductive effect on the audio signals.
The direct integration of the relays into the circuit minimises the signal paths, and connecting cables - as required for conventional volume potentiometers - are no longer necessary. The volume control is assembled from discrete precision resistors and gold-contact relays. The result is totally precise channel matching, devoid of distortion and hiss.

Control Circuitry