Highly selective and sensitive FM stereo tuner with low-distortion multiplex adaptor featuring a high degree of channel separation. It has a 4-section gang-tuned radio-frequency amplifier with separate oscillator, five-stage intermediate-frequency amplifier, automatic frequency control, and automatic stereo/mono switching.

Large tuning meter facilitates pin-point tuning and provides relative signal-strength indication. An automatic data-processing centre switches from mono to stereo when the signal-to-noise ratio permits stereo reception (and if the set is tuned to a stereo broadcast). Moreover, it automatically cuts out the signal if the field strength drops below the critical level – and between channels, during tuning. The automatic frequency control circuit also ensures that the set stays accurately tuned at all times. The remarkable sensitivity of the Beomaster 5000 is due to the use of multi-stage radio-frequency and intermediate-frequency amplifiers, and the large number of intermediate-frequency circuits provide knife-edge selectivity. An amply-dimensioned true slide-rule dial with station markers ensures easy and rapid tuning.” – taken from the 1967 – 1968 Bang & Olufsen product catalogue

Bang & Olufsen’s Beomaster 5000 FM tuner, Beolab 5000 amplifier and Beovox 2500 Cube loudspeakers were among the first product series designed by Jacob Jensen in 1967. The first was Beomaster 1000 in 1964.

The traditional style for tuning knobs was replaced by an exact measuring instrument akin to the slide rule which was considered an innovation in changing the future of radios and amplifiers. The interface, in its precision and simplicity, proved to give the user optimal functionality. This solution had never been seen before and laid the foundation for the future form language of B&O. Beomaster 5000 was an FM tuner, with elimination of static between stations and a built in ‘data base’ which automatically tuned in on stereo broadcasts.

Partner to Beomaster 5000 was Beolab 5000, an amplifier with a similarly-designed slide rule interface.

At the 1967 spring fair in Hanover, B&O received the IF award for Beomaster 5000, BeoLab 5000 and Beovox 2500 Cube for outstanding and user-friendly design.

This continued the B&O theme of receivers with built in speakers, the receiver at the centre of the product being the Beomaster 901. Very slim and elegant if inordinately long!

The amplifier section of this receiver had outstanding technical data: harmonic distortion was less than 0.1% at maximum power output and 0.06% at 50 mW. Frequency range was 20-30.000 Hz and effective bandwidth 10-35.000 Hz.

Frequency correction facilities were the LOW filter which reduced rumble on records (12 dB per octave at 80 Hz) and the HI filter which damped hiss (12 dB per octave at 4000 Hz). With the LOUDNESS control you could switch between objective and subjective linear reproductions. Beomaster 4000 had facilities for stereo and ambio reproduction. There were sockets for a record player and two tape-recorders, one allowing A\B monitoring. The headphone connection was placed on the receiver’s front. All inputs could be adjusted to give equal volume from all programme sources. The FM section had six pre-set stations. A light indicator assisted accurate tuning and an illuminated meter indicated the strength of a station. Field effect transistors, ceramic filters and integrated circuits were used.

When combined with a built-in record deck, the music centre was known as Beocenter 3500.

Receivers and amplifiers with the ambio function were products which, apart from stereo, could also reproduce the ambience or sound information of a room. Ambient information was included on most stereo vinyl recordings but could not be reproduced by a sound system with two loudspeakers or an ordinary stereo amplifier. Bang & Olufsen systems with the ambio function had facilities which electronically subtracted the difference signal (i.e. the difference between left and right channels) which contained ambient information. This information was fed into two extra loudspeakers which were placed as side speakers in a room. Ambiophony was an extension of stereo reproduction and enhanced the sense of realism. It could be used with nearly all stereo programme materials.

“Ambio is an extension of the type of sound reproduction known today as stereo.

Ambio is reproduced through four loudspeakers – two more than required for stereo.

Ambio is sensed as being more spatial and acoustically more life-like than conventional stereo. The sound picture has greater depth because you get the added feeling of being present of the concert hall, listening to the actual performance. Ambio is based on the principle that in the concert hall you not only receive sound impressions directly from the performing group, you also get reflections from the wall and ceiling. The spatial sensation is instrumental in providing the auditory experience and even a two-speaker stereo system will not bring it out fully. And you cannot accomplish the effect by connecting additional speakers to a conventional stereo amplifier because you still have the same left and right front signals merely distributed to more speakers.

In the Beomaster 4000 the left and right channels are subtracted from each other electronically and the resulting difference signal contains a certain amount of spatial information which is fed to the two new side speakers.

Many existing stereo records, FM broadcasts and tape recordings contain this spatial effect to a greater or lesser extent. In a concert hall, room acoustics will be recorded together with the actual programme material, appearing as time-delayed signals in both left and right channels. Recordings made in a strongly damped studio contain few time-delayed signals and the spatial sensation will therefore depend on how the producer mixed the sounds from the various instruments, perhaps adding acoustical effects by electronic means.

Multi-channel records such as SQ records, which are intended for use in a four-channel matrix system in order to bring out the sound effects , can be played successfully through the Beomaster 4000.

A good quality stereo turntable will provide ambio reproduction of both stereo and SQ records through your Beomaster 4000″