The Audio Research Reference 7 is a new-generation tube line-stage preamplifier developed from the same engineering platform as the flagship Reference 20. Rather than updating an existing circuit, Audio Research designed the Reference 7 as part of a new generation of Reference-series electronics, carrying over the mechanical, electrical and power-supply developments introduced with the Reference 20.
The Reference 7 uses a fully balanced signal path, two 6H30P dual-triode tubes and a new multi-metal chassis designed to control mechanical resonance. Suspended, mass-loaded circuit boards provide additional isolation for the audio circuitry, while a solid-state regulated power supply is used to reduce noise and improve long-term stability.
New Reference-Series Architecture
The Reference 7 shares its fundamental mechanical architecture with the Reference 20. Its chassis uses multiple layers of different metals to manage vibration and resonance, while the circuit boards are mechanically suspended and mass-loaded.
Audio Research also incorporates reference-grade output coupling capacitors derived from the Reference 20 design. The combination of the new mechanical platform, regulated power supply and tube line stage is intended to preserve low-level detail without making the presentation overly analytical.
Tube Line Stage
Two 6H30P dual-triode tubes are used in the audio circuit. The 6H30P has been a key part of Audio Research's higher-performance line-stage designs for years, providing substantial current capability for a tube device.
The Reference 7 provides 12dB of gain through both its balanced and single-ended outputs. Its 25kΩ input impedance and relatively low output impedance allow it to interface with a wide range of source components and power amplifiers.
Balanced and Single-Ended Connections
All seven inputs are available in both balanced XLR and single-ended RCA configurations, providing extensive connectivity for a multi-source reference system. The Reference 7 also provides both balanced and single-ended main outputs.
The two main outputs can be used to accommodate multiple amplifiers or other system components, while the additional recording output provides a dedicated connection for recording equipment.
Precision Volume Control
Volume is controlled through a precision resistor-ladder network rather than a conventional potentiometer. The control provides 103 individual steps for precise adjustment while maintaining channel balance throughout the volume range.
The Reference 7 uses a modern control interface while retaining the substantial, machined-metal construction expected of an Audio Research Reference component.
Key Features
• Reference-series stereo tube line-stage preamplifier
• Developed from the same platform as the Reference 20
• Fully balanced circuit architecture
• 2 × 6H30P dual-triode tubes
• Multi-metal, layered chassis
• Suspended, mass-loaded circuit boards
• Solid-state regulated power supply
• Reference-grade output coupling capacitors derived from Reference 20
• 12dB gain, balanced and single-ended
• 7 inputs, each available through XLR and RCA
• 2 main outputs, balanced and single-ended
• Dedicated recording output
• Precision resistor-ladder volume control with 103 steps
• Balanced and single-ended connectivity
• Hand-built in Minnesota
• Available in black or silver