Audio Research - Classic 60 Tube power amplifier

Audio Research Classic 60 Amplifier

The Audio Research Classic 60 is a hybrid power amplifier (valves and transistors) with FET circuitry. A true colossus of sound, very musical, delicate, subtle, clean, with an addictive transparent sonic detail and surprisingly impressive channel separation!

This unit has just undergone a service and cleaning with replacement of all valves (which have not yet reached the initial 30 hours of operation). I would say it is “as new” despite its age.

Power specifications do not always reflect the real capabilities of an amplifier. Qualities such as dynamic stability, clarity and subtlety are far more important.

In listening terms, this means an impressive bandwidth, virtually imperceptible noise, and musically satisfying sound pressure levels (SPL) at drastically lower gain settings. Dynamics, timbres of individual instruments, soundstage and musical emotion emerge from a velvet-black silence. This amplifier opens the window of transparency in a way that offers a deep and wide soundstage, giving us great pleasure and long hours of listening without any listening fatigue.

In short, the Classic 60 reveals a much more complete musical program than amplifiers with a nominal power two, three or four times higher than its seemingly modest 60 W per channel (at 16 ohms). But the Classic 60 is more than capable of driving practically any speaker, even in large listening rooms.

Usability is also among the main attributes of the Classic 60. For example, the automatic biasing keeps the DC balance of the output valves, while the valve bias continuously adjusts to variations in input voltage. Performance remains flawless without annoying adjustments or corrections. And the silent cooling by fan, together with triode operation, means a significantly longer valve life. A Classic 60 owner can expect years of low-maintenance performance.

Technical specifications:

- Output power: 60 watts per channel at 16Ω (stereo)
- Frequency response: 15 Hz to 20 kHz
- Total harmonic distortion: 1%
- Damping factor: 30
- Input sensitivity: 0.55 V
- Signal-to-noise ratio: 84 dB
- Speaker load impedance: 4Ω to 16Ω
- Valve complement: 8 x 6550, 4 x 6FQ7/6CG7
- Dimensions (W x H x D): 480 x 180 x 400 mm
- Weight: 28.6 kg
- Year of release: 1988

The Audio Research Classic 60 presents the classic style, with the power and output transformers at the front of the chassis, behind a brushed aluminum panel, and the valves, filter capacitors and circuit board behind the transformers, under a black wire cage. Two quiet fans at the rear of this cage direct cooling air over the two groups of four 6550 output valves. The inputs are made via gold-plated RCA connectors, while the outputs are obtained from two terminal strips, one per channel, fitted with non-magnetic brass screws.

The only control is a power switch on the front panel, accompanied by two green LEDs and two fuses, one for the power supply and one for the high-voltage regulator of the input and driver stages.

High standard construction and component quality.

An interesting detail is Audio Research’s claim that replacement valves do not necessarily need to be matched, although matched pairs offer better performance.

Given the weight of the amplifier, I prefer to arrange delivery with the buyer; I am available to help find economical and safe transport.

NOTE: speaker cables not included. I can sell them at an additional cost.