Audio Research has introduced the Reference 330M. This model was initially unveiled to the public at the High End Munich event in May 2024, although it was not available for purchase at that time. The first shipments are expected to occur shortly, with options available in either black or aluminum finishes.
The Audio Research Reference 330M is described by its creators as a distinctive model that merges innovative ideas, fresh design, and new components with the finest principles derived from Audio Research’s previous Reference amplifiers. This model utilizes tube technology for all amplification. Initially, the Reference 320M was conceived as a more powerful iteration of the Reference 160M, but it evolved into a sophisticated blend of designs from various Reference models. The concept presented in 2022 was not a finalized product. The 330M, as stated by the manufacturer, represents a significant departure, delivering 330 watts per channel.
The latest preamp takes inspiration from the 610T design, incorporating an ECC83 tube for voltage amplification. The output from the ECC83 is buffered with specialized bipolar transistors that emulate tube characteristics. These bipolar buffers enable the amplifier to optimize the headroom of the input stage while preserving the superior sonic qualities of the ECC83.
The second stage features the traditional circuit found in the 610T and 250 models, utilizing a 6H30 tube differential pair that is biased with a DMOS current source. The output tubes are powered by advanced silicon carbide (SiC) JFETs, which ensure that each output tube receives the optimal quiescent current while also enhancing the driver headroom.
The six output tubes utilized are the latest KT170 type, offering an increased plate voltage margin, peak cathode current, and plate dissipation. Their sound is exquisite, characterized by a rich musicality. When integrated into a well-engineered circuit, the KT170 achieves an unparalleled performance level.
The power supply incorporates solid-state regulation for the front end, complemented by tube regulation (6H30 and 6550) for the output tube shields and driver stage. Additionally, it features a Pi filter with a substantial choke, effectively minimizing the ripple in the output stage power supply.
The 330M is designed as a fully balanced amplifier throughout its entire signal path. It operates exclusively in Pentode mode, which ensures optimal performance. The selection of screen and plate voltages is optimized for superior linearity. On the rear panel, you will find a balanced XLR input alongside a single-ended RCA input, distinct speaker connections for both 8 Ohms and 4 Ohms, 12 Volt trigger inputs, RS-232 control, a tube hour meter, a 20A IEC mains connection, and an adjustable fan speed feature.
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