(2000-2006) Active column loudspeaker
Type numbers: 6841, 6842, 6843, 6844, 6845, 6846, 6849
The Beolab 1 was the first truly active loudspeaker to top the B&O range. Replacing the Beolab Penta 3 (which was amplified as opposed to active), it brought some interesting innovations. The most striking of these was that the cabinet could be ordered in different colours, which were applied to the slender oval section aluminium tubes that formed the main cabinet by anodising and to the frets by using coloured Lycra. The colours offered were chosen to match the Beovision Avant TV range, an acknowledgement that quality loudspeakers were now just as likely to be used for watching films as for listening to music. Text copyright © Beocentral. Unauthorised reproduction prohibited.
The main innovation though with the Beolab 1s was that they used what became known as “Ice Power” amplifiers. The Ice Power division had been set up as a separate entity by B&O to develop high power, high efficiency amplifier, and the Beolab 1 had been the first practical use of this technology. Launched as a real breakthrough, the “Ice Power” amplifier was not a new idea, it was in fact what was known as a “class D” amplifier, something which had been invented very many years previously and that had made appearances in various forms sporadically since the early 1970s. Class “D” techniques had also been popular in other B&O products, the power supply section of the Beovision 8800 of 1979 worked in class “D” and that was one of the main reasons that it used around a third of the power of the Beovision 3200, its equivalent of only 10 years previously. This practice became universal for television power supplies. A class “D” amplifier is basically a pulse width modulator working with an output stage is either driven fully on or cut off (e.g. it works like a switch). The powerful pulse stream that this produces is converted back to an analogue waveform only at the very end of the amplifier by passive reactive components. By these means very little energy is wasted as heat, and as a bonus in a correctly designed system self-generated noise levels can be kept very low. Because of this switching action, the class “D” amplifier is sometimes called a “digital amplifier”, though this description is best rejected as marketing hype. The switching frequency must be high enough not to generate audible harmonic signals in the output, and in the case of the “Ice Power” amplifier it is 384KHz, nearly 20 times higher than the most sensitive ear can detect. To operate at this frequency, highly efficient power transistors are needed, and it was possibly the availability of new ranges of power devices that combined a wide useable bandwidth and excellent switching performance that had re-awakened the interest in class “D” amplifiers for audio in the time leading up the launch of the Beolab 1. Text copyright © Beocentral. Unauthorised reproduction prohibited.
The “Ice Power” amplifier was special in two ways though. Firstly, it employed a really thoroughly resolved system of negative feedback to hone the performance to something that B&O customers demanded. Secondly, by combining the amplifier with the loudspeaker at a stroke resolved two other problems with class “D” operation, the need for accurate load matching and the removal of long loudspeaker leads. In this form the class “D” amplifier formed a really practical solution to the problem of fitting really powerful amplifiers into domestic equipment, where small size and sensible power consumption/heat output were important design concerns. Looking at the Beolab 1, it could be seen that unlike the Beolab Penta 3, there was no bulky external heatsink for the amplifier, which was small enough and sufficiently cool running to be fitted inside the main body of the loudspeaker. Something else that had been considerably reduced was the number of drive units, only 2 bass units were fitted, along with one midrange and one tweeter. The cabinet principle was also different, a pressure chamber instead of bass reflex. Connections could be made either by “Power link”, or by a line-level RCA connector. The latter was provided to allow for easy connection to non-B&O equipment. ABL (adaptive bass linearisation), which was a feature of all Beolab “active” loudspeakers, was included in the Beolab 1. In simple terms, ABL was a volume dependant “loudness” function that was matched to the electro-acoustic characteristics of the loudspeaker. It was automatic in operation and could not be switched off, and so became part of the overall character of the loudspeaker system. In common with the Penta range, a 3 position bass expansion switch was fitted, though this time it was marked with “in corner”, “against wall” and “free standing”, so that its proper use was clear even to non-technical owners. Text copyright © Beocentral. Unauthorised reproduction prohibited.
Beolab 1 was considerably more expensive than the Beolab Pentas had been, but remained the top model only briefly, as soon after its launch the even more expensive (more than twice the price) Beolab 5 was added to the range. Text copyright © Beocentral. Unauthorised reproduction prohibited.