Beolab Penta

(1987-1989) Amplified loudspeaker, 1x150W, Speaker link

Type numbers: 6601, 6602, 6603, 6604, 6605

Beolab Penta was the first B&O loudspeaker to include a built-in power amplifier. Later on this would become the norm, but at the time models such as the Beovox S 80.2, in splendid rectangular teak boxes, were still in the catalogue, and so the Beolab Penta looked radical indeed. At the base of the Beolab Penta was the Beolab 150 amplifier, which is described separately elsewhere. The loudspeaker unit itself was also available on its own as the Beovox Penta, but it is as a single model that both the units were best known and most often seen. Text copyright © Beocentral. Unauthorised reproduction prohibited.

The loudspeaker unit contained a total of 9 drivers and two reflex ports, the largest number fitted to any B&O loudspeaker. The layout was symmetrical, with the bass ports outermost, followed by two groups of two woofers. The 4 midrange units (wired in two sets, the two outer ones and the two inner ones receiving slightly different signals) and the single tweeter were mounted in a separate bay in the centre, and all the loudspeakers were fed from a very complex passive crossover/phase corrector network. It is important to understand the no Penta loudspeaker was ever truly “active”, as is often claimed. An active loudspeaker in B&O terms refers to a model where the crossover takes the form of an electronic filter and separate power amplifiers feed each group of drivers. The Beolab 2500 was the first model offered to work like this, but the technique was really popularised by the Beolab 8000. Text copyright © Beocentral. Unauthorised reproduction prohibited.

Beolab Penta also included a display, which showed which source was playing and the volume level. An “auto limit” indicator was also fitted to show that distortion had been identified and was being surpressed. Easily dismissed as a silly gimmick, the displays were very useful in the context of a linked room in a Beolink system, where of course, as the volume could be set independently, amplified loudspeakers were at their most useful. Text copyright © Beocentral. Unauthorised reproduction prohibited.

The pentagonal cabinets were made of a similar resin that the fronts of the “Uniphase” loudspeakers had been moulded in. The pentagonal section was claimed to offer an acoustic advantage as there were no parallel opposing faces inside, aiding in the damping of internal reflections. The outsides were clad in stainless steel, polished to a soft sheen. This finish reflected the colours of the surroundings whilst not reflecting the image of any specific object, helping the large loudspeakers to blend in. Whilst even this could not make them disappear, they certainly were not the eyesore that some large loudspeakers could be. B&O claimed that the Beolab Penta could provide undiminished performance regardless of placement, and where this true it would have been a genuine breakthrough in loudspeaker design. What the claim in fact referred to was the “bass extension” switch fitted to the Beolab 150 amplifier, which when used with the Penta loudspeaker compensated for positioning in a corner, against a wall or in free space. Excellent stereo imaging was also claimed, due in no small part to the tweeter and midrange drivers being more or less at ear-height for a seated listener. Text copyright © Beocentral. Unauthorised reproduction prohibited.

Beolab Penta proved to be a really strong seller, and was often teamed with the Beosystem 5500 or the Beocenter 9000. The high price was offset by its elegant appearance and excellent performance, though despite this it was largely ignored by the wider Hi-Fi community. The Beolab Penta was replaced by the Beolab Penta 2 in 1990. Text copyright © Beocentral. Unauthorised reproduction prohibited.

(1987-1991) 3 way loudspeaker, 150W

Type number: 6611

The Beovox Penta was a Beolab Penta without the amplifier or display. In some ways this made it more attractive, the slightly reduced height in particular made a real difference to the overall impression of size and made the loudspeaker easier to install discreetly. One did have to accept, in the context of a B&O based system, that the power output would be at best a third of what the Beolab Penta could manage. This would be of course when the Beovox Penta was used with the excellent Beomaster 5500, a system which would prove very satisfactory at sensible listening levels. The only way to improve on this would have been to use a pair of Beolab 150 amplifiers, though this would represent a somewhat pointless approach to system building, and it would only yield a slightly more complex and bulky form of Beolab Penta with no display. Owners of the older Beomaster 8000 could greatly benefit from the Beovox Penta, though the 8000 could “only” deliver 100W into the 8ohm load they presented (as could the Beovox MS 150s that the 8000 system originally included). The Beovox Pentas though would have certainly been easier to integrate into a practical domestic interior than the massive MS 150s. Text copyright © Beocentral. Unauthorised reproduction prohibited.

The Penta loudspeaker required very few changes to be sold in Beovox form. Screw binding posts for the cables were already fitted to the base in the Beolab version, so all that was needed was to shorten the mounting studs and fit the stands directly to the bottom of the cabinet. Larger front frets were also fitted to cover the hole left by the now absent display unit. Text copyright © Beocentral. Unauthorised reproduction prohibited.

The Beovox Penta sold steadily in small numbers, but was eventually withdrawn as the Beolab version proved very much more popular. Text copyright © Beocentral. Unauthorised reproduction prohibited.

(1990-1991) Amplified loudspeaker. 1x150W, Speaker link, Power link

Type numbers: 6621, 6622, 6623, 6624, 6625

The Beolab Penta 2 was a development of the original Beolab Penta. Despite a thorough re-design, the basic principles and appearance remained the same, as did the power output of the Beolab 200 amplifier. The main reason for the changes was to include the new “Power link” connector, which is fully described, along with the Beolab 200, elsewhere. The other notable change was that the displays were altered, and now could display 12 alpha-numeric characters. A light sensor was also fitted, to dim the displays when the loudspeakers were used in subdued lighting conditions. A switch fitted under the amplifier set the displays to work from either and audio or video source, something made necessary as many of the Beovision TV sets of the day included a power link connector. Text copyright © Beocentral. Unauthorised reproduction prohibited.

The Beolab Penta 2 continued the pattern set by the original Beolab Penta, in as much as it was popular despite its high asking price. The Beolab Penta 2 was replaced by the final model in this series, the Beolab Penta 3. Text copyright © Beocentral. Unauthorised reproduction prohibited.

(1992-2000) Amplified Loudspeaker, 1x150W, Speaker link, Power link

Type numbers: 6631, 6632, 6633, 6634, 6635

The Beolab Penta 3 was the last model in this long running series of high-powered amplified loudspeakers. The changes between the Penta 2 and 3 were minimal, with only the display unit being altered. All other parts were unchanged, and performance was identical. The Beolab Penta 3 could be used and was occasionally seen with the AV 9000 surround-sound television and audio system, though to equip this set-up with 4 Pentas required colossal expenditure. Text copyright © Beocentral. Unauthorised reproduction prohibited.

Beolab Penta suffered comparison with Beolab 8000, a new strikingly elegant loudspeaker using an “active” crossover system. This demonstrated the new direction for B&O loudspeaker design, and the Beolab 1, which replaced the Beolab Penta 3, was in many ways a larger Beolab 8000. Text copyright © Beocentral. Unauthorised reproduction prohibited.