Audio Research has launched a new integrated tube amplifier called the I/70. Its four 6550-type output tubes deliver 2 x 70 watts of power, which should be sufficient even for insensitive speakers. The Audio Research I/70 is expandable with two optional modules, one for use with digital sources and the other for use with a turntable.
Powerful tube amplifier with automatic bias control
The core of the Audio Research I/70 integrated amplifier’s design is its output stages, which feature four 6550 tubes for a rated output of 2 x 70 watts. A key feature for practical use is the automatic bias control. This ensures that the 6550 tubes always operate at their optimal operating point, without the need for manual adjustment. Besides ensuring consistent sound quality, this also extends the tubes’ lifespan and reduces daily maintenance.
The Audio Research I/70 integrated amplifier’s design language is inspired by the Reference 330M monoblocks. The clean lines, exposed tubes, and robust cabinet emphasize the unit’s high-quality ambitions. The amplifier is available in natural silver or black anodized.
For added convenience, a newly developed metal remote control is included, allowing precise control of all essential functions. This remote control is designed to reflect the high quality standards even in daily use.
Preamplifier, output transformer, and signal routing
The integrated preamplifier is an active tube circuit and not only controls the volume but also provides the sonically crucial drive for the power amplifier. Audio Research relies on a clear separation of functional components within the device to maintain dynamics and transparency.
A key component of a tube-based power amplifier is the output transformer. The manufacturer claims to pay special attention to the output transformers, which, according to Audio Research, are identical to those in the Reference 75SE amplifier. These components are considered crucial for impulse response, frequency response, and bass control, and are intended to give the I/70 a clear link with the more expensive Reference series.
Headphones, Connections, and System Integration
The Audio Research I/70 integrated amplifier is designed not only for traditional speaker setups but also takes into account the increasing importance of high-quality headphones. These are driven directly by the 6550 output tubes, which, according to the manufacturer, should enable a particularly direct and dynamic listening experience.
For integrating external components, XLR connectors are available for balanced signal sources in addition to unbalanced inputs. Furthermore, the amplifier offers preamp outputs and a dedicated subwoofer output, allowing the I/70 to be flexibly integrated into larger stereo or subwoofer systems.
Optional modules for digital and analog sources
To meet various listening preferences, the Audio Research I/70 integrated amplifier can be optionally expanded with modules. An optional DAC module adds digital inputs, namely USB, coaxial S/PDIF, optical S/PDIF, and Bluetooth, enabling direct connection to modern playback devices.
For vinyl enthusiasts, an optional MM/MC phono module is also available, allowing direct connection to a turntable. Both modules can be used separately or in combination, making the I/70 a central hub for a wide range of sources without the need for external devices.
The Audio Research I/70 integrated amplifier is now available from authorized dealers for a suggested retail price of just under $12,000. The version with an integrated phono module and DAC module costs $13,790.
The optional modules are also available separately, i.e., the phono module for MM and MC cartridges and the DAC module, each costing just under $1,200. Both expansions are available together as a combined solution for $1,790.
