Bang and Olufsen Beolab 5000 integrated amplifier.

 

Bang & Olufsen’s brief for the designers was: “Create a European Hi-fi format, which communicates power, precision and identity.”

 Bang and Olufsen Beolab 5000 amplifier

Bang and Olufsen Beolab 5000 amplifier

The entire Beolab 5000 system, of which the Beolab 5000 amplifier was the central part, was Bang and Olufsen's first serious foray into a complete high performance audio system for the home. The Beolab 5000 was first marketed in 1968 and the production ran until 1972.

With the Beolab amplifier, B&O hit the road running as it was immediately recognised as an innovative and reference standard amplifier for it's technical prowess. Today it remains an outstanding amplifier of exceptional quality, both aesthetically and sonically. Rated at 60 watts RMS (into 4 ohms), it was considered very powerful for the late 60's early 70's when it was manufactured, and from personal experience, will still power the vast majority of modern speakers with ease.

One of the many reasons why this amplifier was sonically so successful is the power supply. There is a heavy, substantial, well-shielded transformer and a number of fully stabilised voltages are provided for the various sections of the amplifier, including the power output stages. Unusually,the two channels of the amplifier operate in a phase inverted mode, which lessens the current draw on the power supply during a demanding two channel coherent signal, such as a loud kettle drum strike.

The amplifier has switching for two pairs of speakers,  providing the combined nominal impedance are not rated below 4 ohms i.e two 8 ohm speakers are fine. As an alternative, there is a “central” channel speaker output which provides a single 120 watt mono output when the two channels are combined. Loudspeaker connections are via DIN sockets, but the inputs and line output are replicated as both DIN and RCA sockets on the underside. There is also a gain matching facility accessible from the base. This adjusts the input level gain of each source in order to avoid a change in level when switching between them.

A mains outlet socket was provided on the rear panel to connect a tuner to. A record deck, fitted with either a conventional pickup or a B&O magnetic one, could also be connected, along with a tape recorder, a stereo microphone (for which shielded transformers were included in the circuit) and an auxiliary line source. A line output was also available, for the connection of a high quality 3 head tape recorder.

Note the "test" button. This was used to phase invert one of the inputs, so setting up with a "null" on a mono signal would aid setting up channel balance.

There is an amplifier protection circuit should the speaker terminals be inadvertently short-circuited or an excessive speaker load presented to the amplifier. In this event, the “stereo” and “on” indicator lamps will flash when the protective circuit operates.

The use of sliding controls for volume, bass, treble and balance was an innovative feature designed to assert mathematical precision and authority. Such an approach on domestic equipment was rare indeed at the time, though other manufacturers soon followed. Incidentally, this became the pattern for many future B&O developments, such as the tangential tracking tone-arm. The very best was made of the styling possibilities that sliding controls allowed, and the fascia looked sleek and uncluttered. The use of the best quality parts and materials ensured these new controls operated perfectly smoothly

At the 1967 spring fair in Hanover, B&O received the IF award for the BeoLab 5000 for outstanding and user friendly design.

BeoLab 5000 Amplifier Product Specifications

Type: 5303 (1969 - Dec 1972)
Power output: 2 x 60 W
Speaker impedance: 4 ohms
Frequency range: 20 - 20,000 Hz +/- 1.5 dB
Distortion: 0.2 %
Intermodulation: 1 %
Signal-to-noise ratio: -90 dB < 60 W
- 58 < 50 mW
Bass control: +/- 17 dB 50 Hz
Treble control: +/- 14 dB 10 kHz

Outputs:
Tape DIN
Line out DIN
Line out RCA
Power supply: 110 - 130 - 220 - 240 V
Power consumption: 45 - 325 W

Dimensions W x H x D: 47 x 10 x 25cm
Weight: 10.4 kg

Connections: Inputs: DIN; MIC DIN
Phono high DIN - RCA
Phono low DIN - RCA
Tuner high DIN - RCA
Tuner low DIN - RCA
AUX DIN - RCA
Tape DIN - RCA