Bang & Olufsen (B&O) is a Danish company founded in 1925 that designs and manufactures audio products, television sets and telephones. The first significant product was a radio that worked with alternating current, when most radios were run from batteries. B&O developed electronically controlled tangential turntables in the 1970s, starting with the Beogram 4000.
The Beogram 4000, as well as being a styling triumph, was a technical tour de force. The large and weighty platter was belt driven by an electronically regulated servo motor, when idler drive and induction motors were still the norm.
What really set the Beogram 4000 apart though was the arm. Actually it had two, both of which were moved under the control of an electronic analogue servo, at a tangent of a fixed angular relationship to the record, keeping the pickup at the same angle to the groove as the cutter would have been at when the master was cut. This system was known as tangential tracking, and remained in use with minor updates until the last B&O’'s last turntable, the Beogram 7000.
The centre bearing, a massive assembly, and the mechanical parts of the arm control system, and the arm itself, were all mounted on a die cast sub-chassis, suspended from the main chassis (also die cast throughout) from steel wires hung on tapering single leaf springs. These three spring assemblies, adjustable for levelling, supported the sensitive parts of the record player, and effectively isolated them from external vibrations, be they from the loudspeakers or from dancing feet. This method of suspension, called either “pendulum” or “danceproof”, was patented and featured as part of all subsequent Beograms.
Such was the superiority of the 4000 that it was bought for use by people who did not normally buy B&O, and was used with all makes of equipment. To perform at its best though, a proper Beomaster receiver should be used.
The styling of the Beogram 4000 is recognised worldwide as a masterpiece, and features in the permanent collections of many museums.