The design, circuit concepts, components and parts of the two R-series integrated amplifier models are identical. However, they differ in output power, connection options and cabinet. The input and output parts are equipped with professional connectors (XLR and RCA) made of amagnetic materials and hard gold-plated contacts. All bushings are firmly screwed to the solid aluminum back panel. In the R-Series, volume control and input selection are handled by gas-tight encapsulated gold-contact relays that show no contact problems due to corrosion, dust or aging, even after many years of operation. By integrating the relays directly into the circuit, the signal paths are optimally short and the signals reach the preamplifier boards without crosstalk from the input sockets. If desired, input 4 can also be equipped with high-quality phono preamplifier modules that have different circuit topologies for MM or MC systems.
The preamplifiers and power amplifiers are built according to the double-mono principle. We completely separate the left and right channels (also mechanically) and use identical circuit boards so that both channels have exactly the same sound behavior. The two separate amplifier boards with input section, volume control, high voltage amplifier and current amplifier stage are located in the right part of the cabinet and are shielded from the power supply and output section by the massive heat sink. As in the HV series, the circuit topology of the input stage is based on a cascode differential amplifier with hand-selected audio J-FET transistors and fully discrete stages without operational amplifiers. Due to this circuit design and the high quality of the components, virtually no over-all negative feedback is required. The subsequent voltage amplifier stage and the following current amplifier are completely galvanically isolated from each other. Thanks to this uncompromising concept, there is no feedback of the loudspeaker currents into the voltage amplifier stages and complete freedom from loudspeaker load effects.The amplifiers are equipped with a channel-separated tone control function that can be fully bypassed by gold-contact relays and with loudness adjustment that can be set to the loudspeaker efficiency.