Multicare, Author at Beoworld

Posted on August 29, 2024August 29, 2024 by Multicare

Linear Tracking Decks

Minimising the distortion

It is really no coincidence that all black vinyl records are cut even to this day on the linear tracking principle. Experience through the years has taught that there is no other way to ensure absolute fidelity and accuracy. Individuals don’t have to be ‘techno nerds’ to appreciate the advantages of linear decks over conventional radial tonearms. Because the stylus sits more comfortably in the grooves, there is less room for tracking error. Which in turn means that there is less risk of sound distortion.

In 1972 with Beogram 4000 Bang & Olufsen used the linear deck principle and developed the world’s first electronically controlled linear, or tangential, tangential record deck. In this pioneering concept, the pick-up moved in a straight line towards the centre of the record parallel with – or tangentially in relation to – the groove. By doing so, the small angular error which would otherwise occur when the pick-up arm moved in an arc on a conventional radial gramophone was removed. Actually the separate arm with its light source and sensor was only used for checking the presence of a record on the platter. This was done by the reflected light being interrupted by the record support ribs of the platter causing a strobed voltage. This strobe would stop the circuit from allowing the pick-up arm from being dropped down onto the platter without a record. It was used to check record sizes as well. The actual drop position was selected and set by a mechanical switch contacts, being allowed when the strobed light source was blocked by the record. Also, when a 7″ diameter record was found, the Beogram 4000 would automatically change speed from 33 1/3 rpm to 45 rpm.

The correction for the offset angle of the pick-arm as it followed the record grooves, was controlled from underneath the deck plates, by a metal paddle that had a small slot, attached to the pivot for the tangential pick-up arm. This paddle was sandwiched between a light source above and two photo cells underneath. When it moved inwards it would let some light onto the inner light cell, this causing an error voltage to drive the arm transport motor. Initially the BeoGram 4000s had an outer sensor, where the arm would be driven outwards, in fact it would track a record cut with a spiral groove cut from the centre to the outside. The BeoGram 4002/6000 used more light/sensor circuits with a perspex slide with vertical gratings of various widths to control the arm positioning for auto dropping the pick-up at the lead in edge of the record, and when the arm accelerated at the run out the increased speed would be detected as a higher strobe speed and cause the arm to be lifted and returned to the resting position.

This other, sophisticated mechanical design, the double tone arm, demonstrated the break with the past. By using two arms, it was immediately clear that this was a gramophone which worked in a new and different way. Bang & Olufsen’s tangential turntables – Beograms – automatically registered whether the record that you put onto the deck was an LP or a single, and set the speed accordingly – 33 rpm (revolutions per minute) for LPs and 45 rpm for singles.

The special benefit of the tangential arm is that it helped to secure the most authentic reproduction of sound from records because it tracked records in the same way they were cut.

Tangential Drive system

However, the tangential arm was only one of the features that contributed to the achievement of the company’s goal. To secure constantly accurate rotary speed a Tangential Drive system was developed. It incorporated a quartz-controlled electronic flywheel, similar to the system used in electricity meters. Like your domestic meter, the system is highly reliable and extremely accurate. It works all day, everyday and never needs repair. You never needed to make corrections in the Beogram’s rotary speed. A digital display kept you informed of speed during play. Because the conventional motor was discarded, there were no motor vibrations to distort the sound. A unique pendulum suspension system prevented external shocks and vibrations from affecting sound reproduction.

Optimal sound and minimal record wear

The short, rigid tangential arm was suspended by Bang & Olufsen’s patented OPP (Optimal Pivot Point) system which prevented disturbing vibrations from being transmitted to the cartridge.

All in all the tangential Beogram system worked extremely well during the time that they were produced and went a long way in making Bang & Olufsen the world name in innovative technology that it is today.

Posted on August 29, 2024August 29, 2024 by Multicare

Integrated Record Players

The Benefits

(1) The anti-skating device is an integrated part of the arm

(2) With tangential arms, anti-skating devices are unnecessary

(3) The speed of the motor is kept constant , regardless of variations in mains current

Even for the experienced hi-fi enthusiast, choosing a record-player could be a headache which often ended in disappointment and irritation. This was because most high-fidelity record-players were sold as separate construction units. It was possible to buy a motor and a cabinet from one manufacturer, pick-up arm from another and finally, the cartridge from yet another. There was absolutely no guarantee that the very fine specifications of the individual components were maintained when they were finally connected into a record player.

For many years Bang & Olufsen’s philosophy was this: the greater the degree of integration a manufacturer could give his products by regarding each as an entity, the better the results for the customer. The demand for high specifications was increased in the mid-1970s by the advent of quadraphonic records. A quadraphonic system has to extract four separate sets of sound information from one record groove. An example of the precision equipment designed to meet these demands was Beogram 6000 – an integrated record-player with an electronically controlled tangential arm.

LP record as programme material

An LP is a work of art in two senses: the creative execution and the technique which inscribes musical experiences on to a disc which is both manageable and easy to store. The record is the programme source which has had greatest success in developing satisfactory standards to meet increasingly high demands: high-fidelity, stereo and later four-channel sound reproduction. Naturally, the products used for playing these records should be able to extract these qualities without losing or adding anything.

Pick-up cartridge

Surprisingly, the greatest demands are placed on the smallest unit in the complete system – the pick-up cartridge. The smaller and more compliant the stylus unit, the better and more precisely it traces the groove modulations, transforming them into electrical signals. The pressure which the diamond stylus exerts on the record is not more than 1-2 grams. It is therefore obvious that if the pick-up is to give of its best, the rest of the record-player should be of an equally exacting standard.

Wow and Flutter

The record should rotate at a correct and constant speed. Meeting these demands is not just a question of how strong the motor is or how much the turntable weighs. It is of great importance that the various components are matched to give the optimum solution. Wow and flutter is the name given to unwanted variations in the tone level or frequency of the reproduced sound. It is easily heard on difficult piano pieces as an irritating “fluttering” vibration of an otherwise pure tone. It is measured in percentages. The lower the figure, the better.

Rumble

Rumble is as the word says: a low, irritating rumbling noise – like faraway thunder. It comes either from the record or the mechanical transmission of the record-player. It is measured in dB, the higher the figure, the better. If you wonder why the turntable and the pick-up arm on a Bang & Olufsen record-player were elastically suspended, the answer is that this was a good way of reducing rumble.

Anti-skating

If you placed a grooveless record on your turntable, the stylus would be automatically pulled towards the centre of the record. This phenomenon is called skating. It is unwanted because the “pull” results in greater exertion of stylus pressure on the inner groove wall. This skating effect must be reduced if high-fidelity standards are to be achieved. On Bang & Olufsen’s record-players the anti-skating device was automatic. It was not visible because it was an internally integrated part of the arm rather than an externally fitted device.

Tangential arm

When cutting a record, the cutter-head moves in a straight line towards the centre of the record. It is only natural to use the same principle in play-back. However, manufacturers have declined because of the difficulties inherent in mechanical methods and, of course the price involved. Until the time that Beogram 4000 was introduced in 1974, all had been satisfied to let the arm trace an arc across the record’s radius. Bang & Olufsen’s tangential arm solved this problem. A servomotor moved the entire pick-up arm across the record in a straight line towards the centre. Skating was eliminated as there was no “pull” towards the centre of the record. An anti-skating device was unnecessary.

The electronically controlled record-player

Bang & Olufsen’s record-players with tangential arms were electronically controlled: both for preparatory functions and functions during actual play. For example, the record player registered the size and speed of the record, electronically. The speed of the motor was kept constant, regardless of variations in mains current. It became really easy to play a record!

How to handle your records

Collecting records is rather like collecting books. How much pleasure you can get and for how long (i.e. how many times you can play a record) depends on how you handle it. Friction, created when you remove a record from its sleeve, can give rise to static electricity causing the record to attract dust. Hold the sleeve so that the sides bend outwards from the record. Place your index finger in the centre and your thumb on the edge of the record. Do not touch the grooves. Remove the record carefully. Only the edges should touch the sleeve. Replace by reversing the procedure.

Posted on August 29, 2024August 29, 2024 by Multicare

Contrast Screens

Through the glass darkly

We all know the frustration of trying to watch television in daylight when the brilliance of a window reflection on the picture tube makes it impossible to see a part or all of the picture. This also happens to a smaller degree when light-coloured furniture or a lamp is reflected. In general, reflections lower the quality of the picture on a television screen and reduce the pleasure of watching a TV programme.

The optical process of what happens in such a case is that the contrast of the picture is effectively reduced. The Bang & Olufsen solution to the problem has traditionally been to incorporate a contrast screen. Ensuring that ambient light (which creates the reflections) travel twice through a light absorbing contrast screen whereas the picture formed in the picture tube travels only once, the brightness of the reflection is substantially reduced.

If it were possible, a better solution would be to reduce reflections directly. One method is to make the surface of the picture tube rough, either by sanding or etching the front surface of the tube or spraying a matt coating on the glass. This type of treatment does not actually reduce reflections, but by making reflections more diffuse, reduces their visibility. However, it also makes the picture itself fuzzy and less sharp, so that the overall quality is reduced.

A more attractive method is to use coatings. Coatings for glass surfaces have been used for a long time and for many purposes. The first use was probably for camera lenses, where coatings corrected for optical faults in the lens. Later, coatings were used to reduce reflections and also to correct colour reproduction when colour films became available, Most people will know of coatings from the more expensive spectacles, where coated glass is used to reduce reflections.

Anti-reflection coatings can reduce reflections to between 5% and 10% of their original brightness. They work by what is known as destructive interference and use the fact that light travels in waves of specific wavelengths. By coating the picture tube or other glass surfaces with a transparent layer of a thickness of one quarter of the wavelength of light, the light failing on the surface is reflected twice – once from the front surface and again from the rear surface of the coating. The two reflections are now half a wavelength apart and therefore in opposite phase and thus virtually cancel each other to destroy the reflection.

Of course, this happens perfectly for just one wavelength of light (or light of a single colour) and to lesser degrees for the wavelengths close to this. By adding more than one coating of different thicknesses, a more broadband removal of reflections can be achieved. Thus, for example, three coatings are used for the front screen of the Beosystem AV9000. One of the reasons that antireflection coatings are not used more often is that currently the manufacturing process is extremely expensive for large screens, allowing its use only in high-end television sets. However, as it is considerably less expensive for small screens, especially where only a single coating is used, it is a reasonably popular feature for computer monitors.

One of the features of coated picture tubes is that although reflections are drastically reduced, the coated glass appears to have a residual colour. This happens because some light is still reflected from the surface, the colour of which depends on the number and thickness of the layers. The colours that are not perfectly removed result in the colouring of the glass. This does not affect the colours of the picture, which is viewed through the coating and does not depend upon its thickness.

Also, the effectiveness of the anti-reflection coatings falls off at an angle to the screen, as the effective thickness of the coating changes. Seen from an angle, the colour of the reflections changes for the same reason.

Beosystem AV9000 also uses another coating, a thin layer of chrome on the back of the contrast screen. This is an anti-static layer, which is earthed to prevent the build-up of static charge, which can give problems with electrostatic shock. An appealing side effect of the anti-reflection coating of Beosystem AV9000 is that when the black curtain behind the contrast screen is closed, the effect of the coating is apparently considerably reduced, so that the whole screen surface appears to reflect. As soon as the curtain is removed, the anti-reflection coating takes full effect, forming a window in which the brightness of reflected light is reduced.

The human eye has a limited ability to cope with bright and dark areas at one time. In fact the eye constantly adjusts to an average ambient light condition, with the pupil in the eye working as a continuously variable shutter, in a manner similar to that known in aperture mechanisms of camera lenses.

Absolute light level is therefore not important under normal conditions, but only if the difference between the brightest and darkest parts of the scene, known as contrast, fall within the range of our limited ability to appreciate the differences. Thus in bright sunlight, we are unable to see clearly into a region of deep shadow, not because it is too dark in absolute terms, but because the aperture of our eyes is set for bright light, so that the shadow region is beyond our contrast range. This is a very important phenomenon, but it can be easily misunderstood. Also, a change in the average light level results in a relatively slow adjustment to the new conditions, as our eyes change aperture.

It is immediately obvious that the ideal lighting for television viewing is when ambient light has the same average level as the average level of light from the screen area. This of course includes not just the TV picture, but also any reflected ambient light from the screen, and reflection of bright objects in the picture area. An analysis of the combination of these variables, under less than ideal conditions, becomes very complex, but some general rules are provided in the report.

Under normal viewing conditions, when no bright objects are reflected in the screen, contrast always fails with increasing ambient light. Normal contrast can be restored by an equal increase in picture brightness, which, for any TV set, is only possible for moderate increases in ambient light. No picture tube has the ability to equal the luminance of a brightly lit room, not to mention that the life of picture tubes decrease sharply with increased brightness settings.

However, the same picture quality can be approximated by increasing contrast, provided the increased contrast is within the range allowed by the eye. In this case, however, although all details in highlights as well as in shadows are visible, the screen will appear darker. Contrast improvement methods, such as contrast screens, are therefore most effective in high ambient light. In addition, Bang & Olufsen sets are among the few that have built-in automatic contrast correction circuits, specifically to compensate ambient light conditions. As soon as reflections occur on the screen surface, whether it is the reflection of ambient light, or a specific bright object, the situation changes. Increasing picture brightness is no longer able to compensate for the change in the average light level from the screen, but requires the help of increased contrast. Since a contrast screen reduces ambient light reflection as well as increasing contrast, it has a double function.

A TV picture is not continuous, but is switched on and off 50 times per second in the PAL transmission system, and 60 times in NTSC. This results in observable flicker in the picture, and while this is more prominent in PAL than NTSC, it is observable in both. Even when a viewer is not conscious of a flickering picture, it results in eye irritation and after a period, in tiredness. Flicker is most obvious in peripheral vision that is when the TV is seen through the corner of the eye when looking directly beside the picture.

Screen flicker is not only a factor of the picture repeat frequency, but also of screen luminance. More accurately, the cause of this effect is the length of the dark period between pictures, and the size of the aperture of the eye due to the screen luminance or brightness.

The frequency at which flicker is no longer observable is called the flicker fusion frequency. A study shows that repetition frequencies as low as 45 Hz can be flicker free provided maximum luminance on the screen is kept low. This maximum permissible value of luminance will normally be regarded as a dark picture, and result in less than acceptable contrast on a normal picture tube.

With a contrast screen, an acceptable compromise can be made, so that full observable contrast is available with a sufficiently low maximum luminance to avoid flicker in 50 Hz TV systems.

Posted on August 29, 2024August 29, 2024 by Multicare

Ambiophony

Receivers and amplifiers with the ambio function were products which, apart from stereo, could also reproduce the ambience or sound information of a room.

Ambient information was included on most stereo vinyl recordings but could not be reproduced by a sound system with two loudspeakers or an ordinary stereo amplifier. Bang & Olufsen systems with the ambio function had facilities which electronically subtracted the difference signal (i.e. the difference between left and right channels) which contained ambient information.

This information was fed into two extra loudspeakers which were placed as side speakers in a room. Ambiophony was an extension of stereo reproduction and enhanced the sense of realism. It could be used with nearly all stereo programme materials. “Ambio is an extension of the type of sound reproduction known today as stereo.

Ambio is reproduced through four loudspeakers – two more than required for stereo.

Ambio is sensed as being more spatial and acoustically more life-like than conventional stereo. The sound picture has greater depth because you get the added feeling of being present of the concert hall, listening to the actual performance. Ambio is based on the principle that in the concert hall you not only receive sound impressions directly from the performing group, you also get reflections from the wall and ceiling. The spatial sensation is instrumental in providing the auditory experience and even a two-speaker stereo system will not bring it out fully. And you cannot accomplish the effect by connecting additional speakers to a conventional stereo amplifier because you still have the same left and right front signals merely distributed to more speakers.

In the Beomaster 4000 the left and right channels are subtracted from each other electronically and the resulting difference signal contains a certain amount of spatial information which is fed to the two new side speakers.

Many existing stereo records, FM broadcasts and tape recordings contain this spatial effect to a greater or lesser extent. In a concert hall, room acoustics will be recorded together with the actual programme material, appearing as time-delayed signals in both left and right channels. Recordings made in a strongly damped studio contain few time-delayed signals and the spatial sensation will therefore depend on how the producer mixed the sounds from the various instruments, perhaps adding acoustical effects by electronic means.

Multi-channel records such as SQ records, which are intended for use in a four-channel matrix system in order to bring out the sound effects , can be played successfully through the Beomaster 4000.

Posted on August 27, 2024August 29, 2024 by Multicare

Degaussing and Demagnetising

Cathode ray tubes (CRTs) – the glass tube that you look at when watching TV – have magnetic properties which must be properly aligned with Earth’s magnetic fields. If a TV is moved while turned on, colour spots may appear and adversely affect the colour and picture (as shown on the picture).

The larger the CRT, the more sensitive it is. Some 77cm and larger television tubes have a N-S/E-W alignment switch which has to be used depending on where the TV set is used – either in the earth’s northern hemisphere or the southern hemisphere… A common mistake is place speakers next to the TV, or worse still, on top of it. Speakers have magnets which will affect the purity of the TV picture. However, speakers such as BeoLab 8000 and BeoLab 6000 are ‘magnetically shielded’ which means that they are designed in such a way as not to affect the CRT. The speakers – when used in a home theatre set-up, for example – can perfectly happily sit at the side of a TV without adversely affecting the picture.

Colour TVs have an automatic degaussing (demagnetising) circuit built-in. But it produces a weak field and may take a couple of days for it to go away. A simple method of ridding the screen from these unwanted blemishes is to isolate the TV from the mains for 30 minutes or so and then plugging the set back in and switching it on. This demagnetising function often causes a brief buzzing sound. Alternatively, place a compass on top of the cabinet, its needle will twitch violently when the degauss circuit is doing its stuff. Never turn the set round while it’s running; the Earth’s magnetic field will upset beam-landing and purity.

If this does not work, it may be necessary to contact a service company to manually degauss your TV. In some cases a purity alignment may be needed, especially if the TV has been subjected to a fall or has been handled roughly. This is when all three colour guns of a picture tube are aligned to the 3 primary colours: red, green and blue. Using a special video generator, a service technician can select and display a picture with just one gun on.

Better brightness comes from a shadow mask

If the degauss action takes place but there’s still a colour-stain, it’s possible that some local magnetic field is present. Move any speakers at least 2m from the set and degauss once more. If you live in a block of flats or other steel-framed building it may be that the structure itself is magnetic! Test for this by putting the set in the middle of the room, degaussing and trying once more. It may be possible (talk to the dealer) to get the steel joists demagnetised.

In rare cases, an internal component of the CRT called the ‘shadow mask’ can detach and cause this problem. When this occurs, on most occasions the TV set has been subjected to a fall or heavy blow to the cabinet.

Tube strikes

As screens get bigger and flatter, especially those with 16:9 faceplates, the maintenance of colour purity and good scanning geometry makes tremendous demands on tube design technology and manufacturing tolerances. These are now stretched to the limit in both triad (conventional, three gun tubes) and Trinitron types. Most people reasonably expect perfection in a TV for which they have paid over 1,400 euros. And as a general rule, the more you pay the closer you get to perfection.

Showing your true colours

Purity, in picture-tube terms, is the state where the electron beam for each individual colour strikes only its ‘own’ colour phosphors on the faceplate. Poor purity stains one colour with the phosphor light of another, and can be caused by poor manufacturing tolerances at the factory; incorrect setup and alignment of the tube’s deflection yoke or neck-mounted magnetic ‘beam-steering’ rings; external magnetic fields, even those generated by the planet itself; and distortion of the metal shadow mask or aperture grille just behind the viewing screen.

The latter cause, ‘mask-doming’, usually arises from local overheating and expansion, and manifests as a soft-edged colour-stained patch anywhere on the screen where a picture highlight has been stationary for a while. Turning down the brightness and/or contrast settings generally cures it. If colour staining is always present in the same screen area, it’s down to one of the other causes listed above.

If impurity remains after all of the above has been tried, a technician will be required. He will check the settings of the purity rings and the positioning of the deflection yoke, and possibly fix correction magnets on the bowl of the picture tube. If none of these measures work, he may reject the tube as being faulty or out of tolerance. Sometimes external degaussing cures the problem, and the set’s auto-degauss circuit has failed due to a duff positor, relay or connection/contact.

Geometrically correct

Many TV viewers get hot under the collar about picture geometry, primarily the straightness – or rather lack of it – of lines at the edges of the image. This can be checked on a Teletext display. Geometry is governed by the accuracy of the magnetic scanning field generated within the tube neck by the scanning yoke and can be adjusted, to a greater or lesser degree – depending on what the manufacturer provides – by an engineer. The settings are stored in software in an EEPROM chip, and are initially set to optimum by an optical/computer system at the factory. Thereafter the data modulates the scan-coil currents at line and field rate to pull the picture into reasonable shape.

The scan geometry can rarely be made perfect. There are always ‘tolerances’ in the manufacture of the scan yoke, and almost everything in life is a compromise. So it comes down to what’s acceptable, and here things get a bit woolly! It’s very hard to get a figure from any manufacturer, though engineers work on the assumption that a 6mm deviation from a dead straight in a line near the border of a 32in widescreen acceptable.

Beyond the fringe

Another aspect of a colour TV tube’s performance is colour registration, sometimes called ‘convergence’. Bad registration shows up as colour fringing on the outlines of picture features near the corners and edges of the display, best judged in the absence of a pattern generator by looking at a Teletext display. Again it’s difficult to quote a figure, but an error of 2-3mm is acceptable on a big screen, depending again on price, quality and personal taste. There should be virtually no visible colour fringing near screen centre. Good colour registration in outer screen areas depends, once again, on the deflection yoke.

Poor registration may be improved by a good engineer by means of panning and tilting the front end of the deflection yoke and/or by resetting software in the memory chip, the latter particularly on Trinitron models. As with purity, it’s also sometimes possible to make corrections by fixing weak disc or strip magnets to the tube bowl. With all settings and adjustments at optimum, what you get is down to the design and build quality of the scan yoke.

Focussing on colour

Image focus (assuming that the internal focus control is correctly adjusted) is a function of electron-gun design and the sharper the edges and corners of the picture the better the manufacturers have done. Incorrect colour rendering is probably due to the need for colour-drive adjustment rather than any shortcoming of the picture tube, unless it’s old and becoming worn. Even then modern auto-greyscale-tracking technology keeps the colour correct until the electron guns are well down. A good way to check colour-tracking performance is to turn the colour right down and look for tinting in the resulting black-and-white image, in both dark and bright areas.

Leaking colour on a black-and-white image indicates poor colour focus.

Some TV designs offer a black- or dark-stretch feature, in which the gain of the RGB (Red-Green-Blue) amplifiers is made dependent on signal level. This varies the picture’s ‘gamma’ law, and allegedly brings out detail in dark areas of the image. This is no less than deliberate distortion, and is best left switched off!

Plasma and LCD displays

The newer LCD screens are immune to purity and geometry errors and the same applies to plasma panels, because in both these cases the RGB-triad pixels and column/row formations are printed on the rear surface of the faceplate: there is no ‘scanning’ function here. LCD projection sets can only develop colour-registration errors from (rare) optical or mechanical faults, though colour blotching can arise from dust and dirt deposits on the liquid-crystal panels and the optical surfaces; a thorough internal clean by a technician solves this.

Tube-type TV projectors (rear-projection sets) don’t suffer from purity errors and screen-centre registration is easily adjusted automatically or by the user. If this is correct but colour-fringing is present near the picture borders, you require professional help. Numerous internal software presets help to trim beam deflection in the individual tubes and thus precisely overlay the three colours

Posted on August 27, 2024August 29, 2024 by Multicare

VisionClear

Discretely enhancing viewing pleasure

One of the most convincing features of the Beovision range addresses the fact that people watch television around the clock. It’s called Automatic Picture Control, and it’s unique to Bang & Olufsen.

While you’re watching television, the TV keeps an eye on the light level in the room. Close a curtain or switch on a lamp and the MX will automatically adjust itself to give you the best picture possible. A built-in sensor on the front of the panel constantly surveys the light conditions in the room and adjusts colour, contrast and brightness automatically, if a reading light is switched on, or sunlight suddenly floods the room.

Although the sensor isn’t very complicated, it controls virtually all picture adjustments, and Bang & Olufsen considers it to be among the most important elements in judging viewing comfort. Automatic Picture Control is incorporated in all television sets in the Beovision range.

The concept

Beovision VisionClear is a revolutionary electronic method synthesizing technology to translate picture quality into viewing comfort. VisionClear is a simple name for a list of advanced electronics which the viewer experiences, but hardly notices, simply because they work. You could say that they transform picture quality into viewing comfort. The concept includes the following elements: contrast screen, Automatic Picture Control, Automatic Cut-off, Wideband CTI and Adaptive Luminance Peaking (and RGB Scan Velocity Modulation on Beovision Avant). Thanks to Automatic Picture Control and the antireflective contrast screen, any adverse effects of incident light are effectively suppressed.

Dynamic Luminance Peaking gives more accentuated rendition of small details and increased sharpness. Colour Transient Improvement (CTI) gives the colours sharper edges, which is especially noticeable when figures in complementary colours are placed next to each other (sports programmes). Scan Velocity Modulation optimises the electron beam to improve the transition from black to white. Auto Cut-Off Control ensures brilliant stability of the picture throughout the lifetime of the TV.

How did it develop?

It had become increasingly difficult to explain the kind of picture quality that Bang & Olufsen was producing. The public wanted explanations and these became difficult to give when the technicians are constantly creating new standards. Accordingly, the concept of VisionClear arose as an overall Bang & Olufsen definition of high-class picture quality: Dynamic luminance Peaking, Wideband CTI, Black Line and, of course, Automatic Cut-off Control.

50 times every second, the colour balance is automatically regulated to give you the most lifelike picture possible. The VisionClear system also includes an (optional) Contrast Screen, which tones down the effects of strong light to ensure that your TV picture stays bright.

Enhancing viewing pleasure discretely

VisionClear is not something you’re meant to notice, but just enjoy. It starts already when you switch on your Beovision. Within a second it adjusts contrast levels, brilliance and colour to match the unique light conditions in the room – and will carry on doing so until you switch off again.

Posted on August 27, 2024August 27, 2024 by Multicare

ICEPower Amplifiers with Bang & Olufsen

ICEPower®

‘Intelligence, Compactness & Efficiency’

ICEPower® is a switching power conversion technology used for audio reproduction. ICEPower® units are characterised by being Intelligent, Compact and Efficient. The ICEPower® series require hardly any cooling; have superb sound quality and competitive total cost efficiency.

Intelligent, Compact and Efficient – and it’s a revolution in amplifier technology from Bang & Olufsen. It offers more power for less energy and produces a minimum of unwanted excess heat. With a size that’s only slightly bigger than a matchbox, it offers incredible freedom to continue to challenge conventional loudspeaker design.

History

As the result of several years of fundamental research within the field of audio power conversion, Bang & Olufsen PowerHouse A/S was founded in 1999. The hard work finally paid off and the exploration of the wide range of ICEPower® applications could begin.

For the first time in the 75-year history of Bang & Olufsen A/S a private person was granted joint ownership. The joint venture between Bang & Olufsen A/S and inventor of ICEPower® Ph.D. Karsten Nielsen was the perfect combination. The established organisation with its experience and well-known quality brand made the ideas of the young entrepreneurial scientist come true.

Turning ICEPower® technology into products requires a flexible organisation, which allows for creating thinking and experimenting, followed by systematic and structured verification of ideas. Only the best ideas turn into exciting and innovative products.

ICEPower® vision

Bang & Olufsen has a remarkably simple technical vision – a quest for point zero, or as stated by Karsten Nielsen:

“We pursue ideal power conversion from any point of view. This means 100% efficiency, zero distortion, zero noise, zero output impedance, zero volume/weight as ultimate research goals – basically a multiplier symbol. Ideal power conversion is indeed quite a challenging journey…”

ICEPower® products

BeoLab 1 – as well as BeoLab 2 – makes use of Bang & Olufsen’s innovative ICEPower® technology. With practically no electric power loss and a greatly reduced cooling space, the new, compact digital power amplifier allows the bass unit in BeoLab 1 to produce a sound far beyond the dimensions of the cabinet.

As the very first product using ICEPower® technology from Bang & Olufsen PowerHouse a/s, BeoLab 1 was released for sale in Autumn 1999. 300 watts of ICEPower® technology are employed for bass reproduction, providing a phenomenal listening experience.

BeoLab 1 takes everything Bang & Olufsen knows about great sound and combines it with the innovative ICEPower® technology. With practically no electrical power loss and a greatly reduced cooling space, the compact ICEPower® digital power amplifier allows a bass reproduction in BeoLab 1 that is far beyond what one would expect from the physical dimensions of the cabinet. BeoLab 1 takes the Bang & Olufsen pursuit of natural sound reproduction to a new level.

Launched in the Spring of 2001, the BeoLab 2 subwoofer adds a new dimension to Bang & Olufsen sound experiences. BeoLab 2, completely based on ICEPower® amplification technology, is constructed as a double-balanced passive radiator system with an 850W ICEPower® amplifier supplying the fuel for one 21cm woofer and two 21cm passive radiators.

Second-generation ICEPower® technology allows Bang & Olufsen to put even more powerful amplifiers in smaller spaces. Furthermore, producing the optimal sound performance in all aspects of both video and audio material has remained a central issue in the creation of all mechanical, electronic and acoustic details.

BeoLab 2 features three custom designed long stroke loudspeaker units. Among other details the active driver has magnetic shielding to allow placement close to a TV set and it utilises a double spider-system for exact control of the linear movement.

Intelligence, compactness and efficiency are what ICE in ICEPower® technology represents. The module uses less electricity, reduces heat and uses 99 per cent of power input to make sound, compared to only 1 per cent in traditional sound systems. This technology can be found in B&O’s top-of-the-line speaker, the Beolab 5. It packs lots of wattage in a small package only 8 cm by 8 cm square and 2 cm thick.

Co-founder and chief technological officer of B&O’s new ICEPower® unit Karsten Nielsen explained: ‘In traditional sound systems, only 1 per cent of the energy the amplifiers receive is used to make sound. The rest is lost as heat. This has been the technology for the last 40, 50 years’

His dissertation for his PhD led to ICEPower®, which switches the electrical supply on and off 400,000 times a second to reduce heat.

Less heat means no clumsy paraphernalia like big heat sinks or fans found on conventional speakers. ‘Because we switch the supply very quickly, we can still maintain high-quality output to the loudspeakers’, said Dr Nielsen.

(Source: The Straits Times, Tech & Science section, 27 June 2001)[/I]

Posted on August 27, 2024August 27, 2024 by Multicare

BeoGram Cartridge Tracking Weights

B&O cartridges all seem to have different tracking weights so we have compiled a list of them for you. Remember that these are a guide only – on the whole, a little extra weight is better than too little. Too little weight will cause mistracking, distortion and record and stylus wear.

The SP range.

SP6/7 2g
SP8/9 1.2g
SP10 1.2g
SP12 1.2g
SP14 2.0g
SP15 1.0g

The MMCX000/MMC20X ranges

MMC3000 1.2g
MMC4000 1.0g
MMC5000 1.5g
MMC6000 1.0g
MMC10E 1.5g
MMC20S 1.5g
MMC20E 1.5g
MMC20EN 1.2g
MMC20CL 1.0g

The MMC1-5 range

MMC5 1.5g
MMC4 1.2g
MMC3 1.2g
MMC2 1.0g
MMC1 1.0g

Soundsmith cartridges

SMMC4 1.2g

SMMC3 1.2g

SMMC2 1.0g

SMMC1 1.0g

SMMC20E 1.2g

SMMC20EN 1.2g

SMMC20CL 1.0g

SMMC20CL+ 1.0g

The Voice 1.0g (except when specified as medium compliance, when 1.3g)

Posted on August 27, 2024August 27, 2024 by Multicare

Dolby Noise Reduction

Dolby Noise Reduction: A brief history of the Compact Cassette

When the cassette tape was first introduced in the early 1960s it did not pretend to be a high-quality format. It was actually developed as a convenient format for voice recording, especially for secretarial work.

In 1970, the arrival of noise reduction for cassettes changed the course of the medium. Dolby B-type both reduced tape hiss significantly and spurred many basic improvements in cassette transports, electronics and tape formulations. Soon the cassette was sounding as good as the LP records of the day and it went on to become an extremely popular and widespread medium for recorded music — one which, even today, continues to provide an unmatched combination of affordable costs, portability, playback versatility and recording capability.

As listeners’ expectations for high-quality playback grew, various improvements on the original Dolby B-type system arose to the challenge. Dolby C-type and S-type noise reduction systems apply the same principles to even more dramatically reduce tape hiss and enhancements like Dolby HX Pro headroom extension improve the quality still further.

Dolby B-type Noise Reduction

Dolby B-type noise reduction is the original Dolby system designed for consumer tape recorders. It is included in all but the least expensive cassette machines today and is used in the preparation of the vast majority of pre-recorded cassettes. It is also incorporated in many stereo VHS videocassette recorded to improve their (mono) linear audio tracks and, in a modified form, in Dolby Surround decoders. Dolby B-type provides 10 dB of noise reduction at the higher frequencies where tape hiss predominates.

Dolby C-type Noise Reduction

Dolby C-type noise reduction was developed to improve the cassette medium still further by providing twice the tape hiss reduction (20 dB) of Dolby B-type. It is offered along with Dolby B-type in a variety of mid-range and premium cassette decks and players. Dolby C-type is also used in many professional VCRs.

Dolby S-type Noise Reduction

Introduced in 1990, Dolby S-type is based upon the principles of the professional Dolby SR (Spectral Recording) process. It not only provides still more tape hiss reduction (24 dB), but also reduces low-frequency noise by 10 dB. Thus, it permits recording high-level signals at the frequency extremes more accurately and cleanly. In listening tests it compares very favourably with CD recordings, with most listeners judging the quality of Dolby S-type encoded tapes as comparable with or in some cases superior to the playback quality of the CD. Dolby S-type is still steadily gaining momentum and is being incorporated first in state-of-the-art decks for the most discerning listeners.

Dolby HX Pro

Not a noise reduction system, Dolby HX Pro makes it possible to record loud musical passages with fewer high-frequency losses and less distortion. It is available in better cassette decks and is also widely used by the recording industry to improve the quality of pre-recorded cassettes through its process of reducing the effects of tape saturation. As no encoding of the signal takes place, no playback decoding circuitry is required to realize the benefits of Dolby HX Pro.

Dolby Headphone Stereo is a new, powerful, digital signal processing system that was developed in 2002 to recreate the sound from each audio channel as if it were being played back from a speaker placed in an acoustically-designed room. In effect, Dolby Headphone Stereo creates virtual loudspeakers in a virtual room. The result is much more dynamic, listening experience: a more natural way of listening to music. Dolby Headphone has the technology to offer three impressive ‘Listening rooms’ which are controlled from the main unit or the in-line remote control they offer. These are:

The Studio: replicates the music played in a small acoustically-damped room, giving perfect sound

Live: recreates a more open live sound as if you were listening to your favourite band on tour

Dome: gives the impression of hearing music in a Large concert hall. Without having to be there

Dolby Headphone FAQs:

1. What is Dolby Headphone?

Dolby Headphone is a signal-processing system that enables ordinary stereo headphones to portray the sound of a five-speaker surround playback system. It does this by virtualising the sound of up to five speakers properly set in a good listening room. It can also be used to simulate a two-speaker stereo system

2. Do I need to use any particular type of headphone?

No, Dolby Headphone works well with all types of headphones, from the inexpensive headsets the airlines provide to high-end electrostatics. However, as with speakers, the better the headphones the better the overall sound

3. Is the “.1” channel on 5.1-channel material reproduced by Dolby Headphone?

Yes. During playback of 5.1 material, the low-frequency effects “.1” channel is mixed into the left and right channels prior to Dolby Headphone processing

4. Does Dolby Headphone require any special adjustments to my system?

No. Dolby Headphone works well for all listeners with normal hearing without the need for any individual adjustments or fine-tuning. This is a significant advantage over previous attempts at virtualising the sound of speakers in a room over headphones where the effect could be quite different from person to person. You will, however, need a system capable of processing audio with Dolby Headphone

5. Can Dolby Headphone be used with DVD-Audio?

Yes. Dolby Headphone can be used with any multi-channel format after it has been decoded back to PCM, including multi-channel music programmes encoded with MLP Lossless on DVD-Audio discs. This means that music lovers will be able to enjoy one of the most exciting features of DVD-Audio on the road as well as at home. For this reason, Dolby Headphone could well give added impetus to broader acceptance of this new super-high-fidelity format

6. What is Dolby Headphone Stereo?

Two-channel stereo products such as CD, MiniDisc, and MP3 and AAC players will feature a two-channel-only version of Dolby Headphone, indicated by the Dolby Headphone Stereo logo. On stereo material, just like multi-channel material, Dolby Headphone gives you a much more natural and less fatiguing listening experience, equivalent to a good two-speaker playback system in a room with good acoustics

7. Does Dolby Headphone create “surround” from stereo programmes?

No, Dolby Headphone does not synthesise quasi-surround from conventional stereo programmes. Think of Dolby Headphone simply as the virtual equivalent of a five-speaker system for multi-channel programmes and as a two-speaker system for stereo material. Just as with your actual speakers, what you hear depends upon how the material was recorded and what kind of surround decoding your playback system incorporates (if any)

8. Does Dolby Headphone work with processors that do create a surround effect?

Yes. Just like a multi-channel speaker system, Dolby Headphone can be used in conjunction with processors that are intended to give a surround effect on stereo material. For example, Dolby Surround Pro Logic II, the latest Dolby multi-channel matrix decoder, provides a wider, more enveloping sound field on many conventional stereo recordings, which Dolby Headphone (in its five-channel mode) will reproduce to great effect

9. I’ve heard that some airlines are showing movies with soundtracks that are pre-encoded with Dolby Headphone. Will I be able to get these movies for playback at home?

Some international airlines offer the benefits of Dolby Headphone to their passengers by showing films with soundtracks that have been specially pre-encoded with the Dolby Headphone process. This eliminates the need to add playback processors to their in-flight entertainment systems. However, there are no plans at this time to offer films with Dolby Headphone pre-encoded tracks to consumers

About Dolby Noise Reduction

While they differ in the details of their operation and the degree of noise reduction they provide, all three Dolby noise reduction systems answer the same question: how can noise be reduced without harming the music?

Unlike simple noise filters, Dolby Noise Reduction systems make no attempt to remove noise once it has been mixed in with the music. Rather, it prevents noise from being added to the music as it is recorded in the first place.

This two-step process first encodes the music when it is recorded and then decodes it when the tape is played back. This is why the Dolby noise reduction system in a cassette recorder should be switched on both when you record a cassette and when you play it back.

In recording, the Dolby NR circuit makes the quiet parts of the music (which are most susceptible to noise), louder than normal. When the encoded tape is played back, the Dolby NR circuit is switched around to in turn lower the previously boosted parts of the music.

This automatically lowers any noise added to the music by the recording process and it restores the music to its original form so that nothing is changed or lost but the noise.

As simple as it sounds in theory, highly sophisticated technology is used in all Dolby NR systems to ensure their unique combination of effective noise reduction and freedom from side effects.

Posted on August 27, 2024August 27, 2024 by Multicare

Auto Dolby

The Dolby noise reduction system was invented to reduce tape noise in professional systems and called the ‘Dolby A’ system.

A later system to reduce noise in domestic cassette recorders was known as ‘Dolby B’. Later, to improve performance in cassette recorders, the improved Dolby C noise reduction system was introduced. For cassette recorders it meant that a tape could be recorded either without noise reduction: with either Dolby B or Dolby C noise reduction systems.

For the consumer it meant that the noise reduction system used during recording needed to be noted in some way for later playback, utilising the same noise reduction system. However, if a tape was recorded with two different noise reduction systems on different parts of the tape, identification became even more complex for replay.

To make things easier for the user, Bang & Olufsen developed and introduced a system to automatically set the noise reduction type on replay, without any user intervention. The system was named ‘Auto Dolby’. Any tape recorded on a recorder equipped with the Auto Dolby system would playback correctly on any other recorder with Auto Dolby system, even if the tape contained recordings using different noise reduction on different parts of the tape.

The system worked by superimposing subsonic tones within the signal to be recorded, with different tones used for Dolby C and for Dolby B. Being subsonic, these tones had no influence on the recorded signal during playback. However, the electronics built into the Auto Dolby circuit detected these signals and switched to the correct noise reduction setting. If no noise reduction was used, no tones were recorded and no noise reduction circuit was set on playback.

This simple system relieved the user from the chore of noting the noise reduction system used for each recording and switching to the correct system during playback, or alternatively, of listening to the recording using an incorrect noise reduction setting.