Beovox range " Speaking out loud is no longer enough for a loudspeaker "
Beovox range (left to right): Beovox S45, S55, S80, S120, MS150, M150; (front) S30, S40
The job of a loudspeaker is to transform electrical oscillation into sound. And even though much has happened throughout
the history of sound reproduction, the basic principles behind even the most modern loudspeaker are nearly ninety years
old because they were developed as early as 1915 by Denmark's Peter L Jensen. He called his new invention the
"thermodynamic loud-speaker".
At the time, the fact that you could even reproduce and amplify sound was revolutionary. It was an epoch-making innovation
that was refined in the years that passed. But as long as the sound sources themselves weren't particularly precise, it wasn't
really possible to create better sound until modern record players and tape recorders arrived on the scene that acoustical
research could again add new dimension to sound.
The introduction of stereo signals placed even greater demands on loudspeakers. And the sophisticated tapes and unsurpassed
compact discs of today have meant that people expect even more in terms of sound reproduction.
At Bang & Olufsen, the company has put well over sixty years of work into acoustic research and the construction of advanced
speakers. Today the company is better equipped to carry on development work than ever before. The objective is to improve
the speaker because richly-detailed sound is more than a question of speaking loudly.
Beovox range of passive speakers (1976 - 1977)
The best loudspeakers leave the colouring and interpretation of sound to the musicians and their instruments. Because the job of
a loudspeaker is simply to recreate an exact acoustic replica of the electrical signal fed to it by the amplifier. Without adding to
or subtracting from those signals. This is no mean job. It involves having a wide, flat frequency response, with low harmonic and
intermodulation distortion, and the elimination of phase distortion and the colouration that can be caused by resonance.
It also requires an exact balancing of components.
Bang & Olufsen pioneered the field of phase distortion research, and remains in the forefront of loudspeaker technology. So all
Beovox speakers gave neutral sound reproduction. The difference between models lie in their ability to reproduce powerful low
bass tones, their power handling capacity, the size of the cabinets and the various placement options that they offered.
The stereo image produced by Beovox loudspeakers sounded wider than the actual distance between the speakers.
You heard a distinct depth and perspective in the sound reproduced. Instruments and soloists were always well-defined and
easily locatable - not squashed, muffled and blurred into an unidentifiable mass. And the spatial clues and acoustic details that
helped us picture a concert hall or room effectively were reproduced with such accuracy and clarity that you had no difficulty in
visualising where a live performance took place.
How big is big?
It is a common error to assume that cabinet size is a fair indication of a loudspeaker's sound quality or power capacity. During
the 1970's this belief had an element of truth, but not at the time of Beovox production. By then, speaker technology advanced
past the point where 'bigger' means 'better'.
Why the angled profile?
The way you perceive sound from a multi-unit speaker is affected by the distance travelled by each part of the frequency spectrum.
If the drivers are all set on the same vertical plane, as in many other brands, the bass tones from the deeply-dished woofer have
to travel further than the treble tones emanating from a domed tweeter. You hear the high frequencies fractionally earlier than the
bass. This effect is called pathway distortion. B&O in their range of Beovox speakers eliminated pathway distortion by mounting
the various drivers on an acoustic axis. Some Beovox models also had provision for an adjustable pedestal which you could tilt
for final orientation at your listening position.
Why 'log-line'?
The three compact speakers - C30, C40 and C75 were specifically designed to overcome the acoustic problems inherent in
smaller rooms i.e. where the walls were less than 3,5m apart. In this constricted space, low frequency sound could bounce back
and forth between opposing walls, building up a 'standing wave' or resonance at a certain frequency. In other words, the room
itself could 'ring' - much like a wine glass flicked with a fingernail.
To overcome this problem, B&O's compact speakers had special cabinets with interior partitions so-placed that the rear radiation
from the drivers followed a path that was not constant because of the logarithmically decreasing flow resistance it encountered on
its route to the rear ports.
An explanation of phase distortion
Phase distortion is the same as distortion in time. Even the best multi-way speakers can suffer from phase distortion. It occurs
when, for the same tone, two drive units vibrate at the same time but in opposite directions: that is out of phase - like feet marching
out of time. So instead of arriving at the ear simultaneously as one integrated sound, some parts of the sound are delayed in relation
to others. As you can imagine, the result is musical reproduction which is not faithful to the original. In the worse cases, the sound
is woolly and muffled. In all cases it is fatiguing and tiresome to listen to for long periods.
The differences in conventional speakers and Bang & Olufsen Uni-Phase speakers were audible in controlled listening tests as a
freer, more open stereo image and more precise definition and clarity, especially on transients. A square wave (below, left) is a
most demanding test for any audio component. Its reproduction by a conventional speaker (below, centre) makes it almost
unrecognizable. However, it is close to the original (below, right) when it was reproduced by a Beovox Uni-Phase speaker.
In addition to Bang & Olufsen's electronic design solution to the problem of phase, the drivers of all models were mounted on
an angled baffle so that they had a common acoustic axis. This means that all tones had the same distance to travel from speaker-
coil to ear and were therefore more likely to arrive at the same time.
Furnishing options
Bang & Olufsen loudspeakers gave you more furnishing options than any other brand. Once you met the criteria for system-
matching you were then free to choose the type of speaker that fitted most readily into your home environment.
If you decided on a free-standing model, it was sensible to raise the speakers to the optimum listening height by fitting them with
their own sturdy metal pedestals. This alone prevented too much of the sound becoming lost in long-pile carpeting and other
domestic furnishings. 'M' models included pedestals as standard. For 'S' models the stands could be bought separately.
Alternatively, Beovox 'S' speakers could be placed on a low table or shelf, or fixed to a wall using the special mounting brackets
available as an optional accessory.
__________________
Mvh. Peter Pan. Se link -
DIN-RJ45-Adapter.-
PPsetup.-
Div.& Diy.
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