BEO.ZONE

BeoMaster 4000

BeoMaster Tuner/Amplifier

Production: 1972 - 1977

Designer: Jacob Jensen

Documents: Owners Manual, Schematic, Service Manual

Beomaster 4000 was one of the few receivers which were able to play back recorded sound both in stereo and in ambiophonics sound. It delivered a full 60W of power through each of its two front speakers, more than adequate to fill any good-sized room.  It was the replacement for the prestigious Beolab 5000 System which was rated equally for the amount of power which it produced.  Positioned above the Beomaster 3000.2 in the range of Bang & Olufsen receivers, Beomaster 4000 was fitted with connections for a turntable as well as two tape recorders.

The in-built receiver was FM-only. As heart of an advanced stereo/ambiophonics system the user could add the following products to it to create a hi-fi system (the Beosystem 4000 - see image below) that was powerful, sophisticated, and really quite ahead of its time:  Beogram 4000 turntable, Beocord 2200 tape recorder, Beovox 5700 main speakers with Beovox 2702 taking up at the rear of the room.

Ambiophonic sound:

It is interesting to note that stereo sound became available in the home in 1958 through vinyl LP phonograph records. As more stereo records became available to the public, it was not long before stereo sound supplanted mono as the standard home consumer format. In the United Kingdom, two-channel stereo FM broadcasting followed shortly afterward in 1961, further enshrining stereo sound as the norm. Compared to domestic music systems, television still only supported mono sound reproduction. The standardization of stereo sound led to a number of experiments which sought to enhance or augment the format in new ways. Ambiophony represented one such experiment in which reverberation signals were reproduced from separate loudspeakers, creating a sense of greater sound envelopment. Few of these systems, however, were commercially viable and so alternative solutions were sought, including the ill-fated quadraphonic format.

In order to deliver four channels of sound via two-channel analog media, manufacturers developed a form of encoding or “matrixing” by which the information from the extra channels could be folded down and accommodated on only two standard stereo channels. To enable the reproduction of quadrophonic recordings in the home, consumers were required to purchase a range of equipment from decoders (to reconstruct the original four channels of audio) through to new amplifiers and speakers, positioned around the listener in a square configuration. The use of encoding to deliver surround sound information through stereo media points to more recent developments such as Dolby Surround. In fact, surviving quadraphonic systems dating back to the 1970s are reputed to be able to decode analog Dolby Surround signals of today.

BeoMaster 4000 technical specifications

Beomaster 4000 Specifications 
Types: 2406, US 2408 (1972 - April 1977) 
Power output 2 x 60 watts/ 8 ohms 
2 x 40 W / 4 ohms 
2 x 100 W / 8 ohms 
2 x 55 W / 4 ohms 
Speaker Impedance 4 ohms 
Harmonic Distortion < 0.06 % 
Intermodulation < 0.3 % 
Frequency Response 20 - 30000 Hz 
Signal-to-noise ratio > 58 dB 
Channel Separation > 45 dB 

Bass control: +/- 17 dB 
Treble control +/- 14 dB 

FM tuner: Range 87.5 - 104 MHz 

Power supply:110 - 130 - 220 - 240 V, 50 - 60 Hz 
Power Consumption: 20 - 275 W 
Dimensions W x H x D: 9.5 x 58 x 27cm 
Weight: 10 kg 

RIAA amplifier: built-in 

Connections: Tape 1 DIN 
Tape 2 DIN 
Phono DIN 
Speakers 2 sets