The BeoLab 4000 was a compact active loudspeaker housed in an unusually shaped cabinet and available in a wide range of colours. The cabinet had the section of an ellipse with pointed ends, frequently described as “leaf shaped”. There were no particular acoustic advantages to this design for such a small unit, other than that it allowed a reasonably large volume to be enclosed whilst still looking elegant and interesting, reason enough for a loudspeaker in this class. The cabinet was of moulded resin and clad in aluminium, making for an accurate, rigid structure. A shaped cloth grille in a colour matching the metalwork completed the exterior. The design principle was bass reflex and two drivers were fitted, a 4.5” woofer with a rubber roll edge and a 0.75” dome tweeter. The electronics followed the familiar Beolab pattern of having two power amplifiers driven by an electronic crossover network. Adaptive Bass Linearisation, a form of tuned “loudness” control, was applied to correct the shortcomings of the small cabinet and drivers, along with the ear’s own deficiencies at low listening levels.
A number of applications were suggested for the BeoLab 4000. Its primary role was as a loudspeaker for the BeoSound 3000/3200, particularly after the Beolab 2500 (a very similar design in truth) had been discontinued. Obviously the BeoLab 4000 could not fit together as a transportable unit with the BeoSound 3000/3200 in the way the Beolab 2500 had fitted to the BeoSound Ouverture, but a wide range of stands and brackets were available for table, floor and wall positioning to make up for this. Other applications included computer loudspeakers (even though they cost more than a decent computer and would put the output of any soundcard to shame) and as a centre loudspeaker (when mounted horizontally, end-to-end) for the Beovision 4 range of display panels. Finally, they were the ideal link-room loudspeaker, making a fitting replacement for the Beovox CX 100.
An unusual feature, aimed towards computer use, was the prominent on/off switch on the front of each loudspeaker. Combined with a red/green status indicator, this allowed the loudspeaker to be operated manually if it was not part of a Powerlink system. Generally a reliable, well developed product, the BeoLab 4000 had only one flaw, the small mains transformer that powered the electronics whilst in “standby” was of poor quality in early examples and would frequently burn out.
During BeoLab 4000’s life, a substantial re-design was carried out, replacing the original linear class A/B amplifier with a class D “ICE Power” unit similar to that fitted to the BeoLab 4. This variant is known as the MK 2 and can be distinguished by the lack of a power switch on the front. Surprisingly, the rated power was reduced though the maximum sound pressure level remained unchanged.
Such acts of rationalisation are common in the B&O range as products evolve or come to the end of their life cycle. Another example can be found in the change from the Beocenter 9500 to the BeoCenter 9300 where the external styling was retained but the internal assemblies were changed to become more like other recent models.