Revox B780 Preamplifier (1980)

The Revox B780 is a high-fidelity preamplifier that stands as a hallmark of Swiss engineering excellence. Released in 1980 as part of Revox’s prestigious B7xx series, the B780 combined advanced analog audio performance with cutting-edge digital control systems for its era. With its motorized volume knob, microprocessor-based operation, and quartz-synchronized FM tuner, the B780 represented a bridge between traditional high-end audio design and the emerging digital age.

Key Features

Quartz PLL synthesized FM/AM tuning for exceptional reception accuracy
Microprocessor-controlled user interface with motorized volume knob
Dual independent power supplies for analog and digital circuits
Dolby FM noise reduction for improved broadcast fidelity
Full tape dubbing capabilities with multiple input/output options
Preamp outputs for integration with external power amplifiers
High-contrast fluorescent display with adjustable brightness

Technical Specifications

Specification	Detail
Year of Production	1980–1985
Manufacturer	Revox (Studer)
Category	Preamplifier with Integrated Tuner
Channels	2 (Stereo)
Output Power (into 8 ohms)	2x 80W (when paired with compatible power amp)
Impedance Range	4–16 ohms (compatible)
Frequency Response (Audio)	20 Hz – 20 kHz (±0.5 dB)
Total Harmonic Distortion	< 0.05% (typical)
Signal-to-Noise Ratio	> 90 dB (A-weighted)
Tuner Type	Quartz PLL Synthesized FM/AM
Tuner Sensitivity (FM)	1.5 µV (50 dB quieting)
Audio Inputs	4 line-level (RCA), 1 phono (MM), tape in
Audio Outputs	Preamp out, tape out (dubbing), headphones
Control System	Microprocessor with motorized potentiometer
Power Supply	Dual regulated supplies (analog/digital separation)
Power Consumption	120 W (max)
Dimensions (W×H×D)	483 × 148 × 375 mm
Weight	14.5 kg

Sound Signature

The Revox B780 delivers a clean, detailed, and neutral sonic character with a subtle warmth in the midrange. Its precise imaging, wide soundstage, and exceptionally low noise floor make it ideal for critical listening. The FM section, enhanced by Dolby FM decoding, offers broadcast reception quality that remains impressive even by modern standards. When used as a preamp, it provides transparent signal routing with minimal coloration, allowing source components to shine.

Historical Context

Part of Revox’s elite B7xx series—sibling to the legendary B77 and A77 tape decks—the B780 was engineered to meet the demands of audiophiles and broadcast professionals alike. Built by Studer in Switzerland, it reflects the brand’s reputation for precision, durability, and innovation. The B780 was among the first consumer preamplifiers to integrate microprocessor control and quartz-locked tuning, setting a new benchmark for tuning stability and user convenience. Its construction quality, with heavy-duty chassis and high-grade internal components, underscores its status as a long-term investment in high-fidelity audio.

Maintenance and Common Issues

Due to its age, the Revox B780 requires careful maintenance to ensure optimal performance:

Capacitor Degradation: Electrolytic capacitors, especially in the power supply, are prone to drying out. A full recapping is recommended for units that have not been serviced in decades.
Motorized Volume Control: The motor-driven potentiometer can wear or become noisy. Cleaning or replacement may be necessary if volume adjustment becomes erratic.
Display Backlight Failure: The fluorescent display may dim or fail over time. Replacement tubes or LED retrofit kits are available from specialist suppliers.
Microprocessor Glitches: Aging ICs or poor connections can cause control issues. Reflowing solder joints and checking connectors can resolve intermittent behavior.
Tuner Alignment: If FM reception is weak or unstable, a professional alignment of the PLL tuner may be required.

Maintenance Tips:

Power on the unit periodically to prevent contact oxidation.
Use contact cleaner on input/output jacks and selector switches.
Store in a dry, temperature-stable environment.
Consider professional servicing before extended use.

Collectibility and Market Value

The Revox B780 holds a solid position among vintage audio collectors, earning a collectibility rating of 7/10. Its combination of advanced technology, Swiss build quality, and integration within the revered B7xx ecosystem ensures continued demand. Fully functional units in good cosmetic condition typically sell for $400–$800, with prices varying by region and included accessories. Models with service records or original packaging may command a premium.

Conclusion

The Revox B780 remains a compelling choice for vintage audio enthusiasts seeking a technically sophisticated, sonically transparent preamplifier with excellent FM reception. Its blend of analog fidelity and early digital control makes it a fascinating artifact of late-20th-century audio innovation. With proper care and restoration, the B780 continues to deliver a listening experience that rivals many modern components.