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 circuits. A true colossus of sonority, very musical, delicate, subtle, clean, with an addictive transparent sound detail and surprisingly good channel separation!

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

Power specifications do not always describe an amplifier’s real capabilities. Qualities such as dynamic stability, clarity and subtlety are far more important.

In terms of listening language, this means an impressive bandwidth, practically imperceptible noise level, 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 to transparency in a way that offers us a deep and wide soundstage, giving us much 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 nominal power two, three or four times higher than its seemingly modest 60 W per channel (into 16 ohms). But the Classic 60 is more than capable of driving virtually any loudspeaker, even in large listening rooms.

Practicality is also among the main attributes of the Classic 60. For example, the auto bias of the output valves is automatically maintained while the valve bias continuously adjusts to input voltage variations. Performance remains impeccable without fiddly adjustments. And the silent cooling by fan, together with triode operation, means a significantly longer valve life. An owner of a Classic 60 can expect years of low-maintenance performance.

Technical specifications:
- Output power: 60 watts per channel into 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 styling, with the power and output transformers in the front of the chassis, behind a brushed aluminum panel, and the valves, filter capacitors and circuit board behind the transformers, under a black mesh 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 taken from two bus bars of terminals, one per channel, these equipped 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 mains and the other for the high-voltage regulator of the input and driver stages.

High standard construction and very high-quality parts.

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.