It was a technical tour-de-force in
its time and can lay claim to being one of the most complex decks ever to enter
mass production. But how does it measure up today?
The Beogram 4000 is as much respected for
its industrial design as it is for its audio performance. Launched in 1972 at a
price of around $270.34, the 4000 was generally the preserve of wealthy music
lovers rather than the traditional hi-fi hobbyist. Despite being expensive, it
sold in large numbers and remained available in various forms until the end of
the decade, when the 4000 series was replaced by a new range of direct-drive
models.
Slim,
elegant and packed with the most advanced technology available, there was no
other turntable quite like the Beogram 4000 when it appeared in 1972 and it
remains a truly iconic design
The Beogram 4000 was an integrated turntable:
in the sense that the motor unit, arm and cartridge were designed together to
work as one optimised system. Prior to the 4000 project, B&O had considered
building a conventional turntable with a long arm but this was rejected in
favour of tangential tracking, the Beogram 4000’s most famous feature.
No
knobs or levers here – all functions are controlled via pressure-sensitive
metal surfaces
At the cost of additional complexity, tangential
tracking sidesteps the geometrical compromises inherent in conventional arm
designs. Since records originate on lathes where the cutting head moves
tangentially, it is logical that the best way to play them is on a deck whose pick-up
follows exactly the same path as the cutting head. The tangential arm on the
Beogram 4000 is short and stiff. Meanwhile, its movement is controlled by an
electronic servo which eliminates the harmful effects of friction and inertia associated
with purely mechanical systems.
Superiority complex
If there was ever a competition for the most
complex turntable ever to enter mass production then the Beogram 4000’s only rival
would surely be the Sony PS-B80. Indeed, a full technical description of the
4000 might fill this entire magazine. The basic structure comprised a die-cast tray
that served as the basis for the slim and elegant plinth. This housed another casting,
which formed a floating sub-chassis. Beogram 4000s were immensely sturdy; some
dealers would demonstrate this fact by placing the unit on the floor and then
stand carefully on the lid!
The
beam of light emanating from beneath the arm is used to sense the presence and
size of records. This non-contact method protects the stylus and the owner’s
LPs and 45s
The suspension was constructed using three
arched spring steel strips from which the sub-chassis hung on fine wires. This provided
highly effective isolation from external vibrations. Onto the sub-chassis were
mounted a substantial bearing for the platter, along with polished chrome runners
which supported the arm assembly. The arm was moved by a lead screw driven by a
servo motor of the ironless core type. This was an expensive component, but it did
allow the arm to move with the finest possible resolution.
The platter, which was another heavy casting,
was belt driven. However, rather than have the motor connected directly to the
mains as was the conventional practice at the time, the designers chose to run it
from an internal precision oscillator. The aim was to create perfect waveforms on
demand. As well as giving the best possible performance, this made automatic speed
selection a realistic proposition and removed the need to provide different motors
for export (60Hz) markets.
The speed could be fine-tuned by the user
and to help with this a stroboscope was fitted. This was printed under the platter
and could be viewed through a small window on the control panel through a
series of lenses and mirrors.
