INTRODUCTION
Thank you for purchasing the B&W CDM™7NT speakers.
Founded in 1966, B&W has always striven for perfect sound reproduction in its products. To this end, the company has invested heavily in research and development in order to maintain its position at the forefront of acoustic design. Through the years, B&W has introduced many advanced features and techniques. Although many of these have been developed initially for the more expensive models, our “waterfall” design policy has seen them incorporated, wherever possible, elsewhere in the product range.
Features to be found in the CDM™NT Series include cabinets with contoured edges to reduce sound diffraction (the radiation of sound waves from sharp edges that interfere with and blur the direct sound from the drive units). An integral part of the CDM™ range is the use of Kevlar® cone bass/midrange drive units for lowest coloration and maximum definition. The treble units incorporate Nautilus™ tube technology, which eliminates resonances behind the dome diaphragm.
It is important to spend time setting up the speakers, as care spent on the installation process will reap the reward of many hours of listening pleasure. Reading this manual fully will help you obtain the best from your audio system.
B&W distributes to over 65 countries worldwide and maintains a network of dedicated distributors who will be able to help should you have any problems your dealer cannot resolve. Their mailing addresses can be found on the web site or by calling B&W direct.
UNPACKING
(Figure 1)
•Fold the top carton flaps right back and invert the carton and contents.
•Lift the carton clear of the contents.
•Remove the inner packing from the product.
•We suggest you retain the packing for future use.
Check in the carton for:
•4 Spike feet with lock nuts
•2 Foam bungs
•1 International warranty booklet
CONNECTIONS
(Figure 2 & 3)
All connections should be made with the equipment switched off.
There are 2 pairs of terminals at the back of the speaker which permit bi-wiring if desired. On delivery, the separate pairs are connected together with high-quality links for use with a single 2-core cable. For single cable connection, leave the links in place and use either pair of terminals on the speaker.
Ensure the positive terminal on the speaker (marked + and coloured red) is connected to the positive output terminal of the amplifier and
negative (marked – and coloured black) to negative. Incorrect connection can result in poor imaging and loss of bass.
To bi-wire, remove the links by loosening the terminal caps and use a separate 2-core cable from the amplifier to each pair of terminals. This can improve the resolution of low-frequency detail. Observe the correct polarity as before. When bi-wiring, incorrect connection can also impair the frequency response.
The terminals accept bare wire. Always make sure terminals are screwed down tight as otherwise they may rattle.
Ask your dealer for advice when choosing cable. Keep the total impedance below the maximum recommended in specification and use a low inductance cable to avoid attenuation of the highest frequencies.
POSITIONING
(Figure 4)
Some experimentation with the position of the speakers is well worthwhile to optimise the interaction between them and the listening room.
However, as an initial guide:
•Do not fit the spike feet until you have found the best position for the speakers.
•Place the speakers and the centre of the listening area approximately at the corners of an equilateral triangle.
•Keep the speakers at least 1.5m (5ft) apart to maintain left-right stereo separation.
•Keep the speaker baffles at least 0.5m (20in) clear of walls. Having the speakers too close to walls increases the level of bass relative to midrange and may give a boomy quality to the sound.
Stray Magnetic Fields
The speaker drive units create stray magnetic fields that extend beyond the boundaries of the cabinet. We recommend you keep magnetically sensitive articles (television and computer screens, computer discs, audio and video tapes, swipe cards and the like) at least 0.5m from the speaker.
FINE TUNING
Before fine tuning, make sure that all the connections in the installation are correct and secure.
If the level bass is uneven with frequency it is usually due to the excitation of resonance modes in the room. Even small changes in the position of the speakers or the listeners can have a profound effect on how these resonances affect the sound. Try mounting the speakers along a different wall. Even large pieces of furniture can have an effect.
Moving the speakers further from the walls will reduce the general level of bass. Space behind the speakers also helps to create an impression of depth. Conversely, moving the speakers closer to the walls will increase the level of bass.
If you want to reduce the bass level without moving the speakers further from the wall, fit the
foam bungs in the port tubes. (Figure 6)
If the central image is poor, try moving the speakers closer together or toeing them in so they point just in front of the listeners. (Figure 5)
If the sound is too harsh, increase the amount of soft furnishings in the room (for example us heavier curtains), or reduce it if the sound is dull and lifeless.
Test for flutter echoes by clapping your hands and listening for rapid repetitions. Reduce them by the use of irregular shaped surfaces such as bookshelves and large pieces of furniture.
Ensure the speakers stand firmly on the floor. Whenever possible fit the spike feet supplied after you have optimised the positioning. These are designed to pierce through carpets to the floor surface. Initially, screw the lock nuts fully onto the spikes and screw the spikes fully into the threaded inserts in the base of the cabinet. If the cabinet rocks, unscrew the two spikes that do not touch the floor equally until the cabinet sits firmly on the floor, and lock the nuts against the cabinet. If there is no carpet and you wish to avoid scratching the floor surface, use a protective disc between the spike and the floor.
RUNNING-IN PERIOD
The performance of the speaker will change subtly during the initial listening period. If the speaker has been stored in a cold environment, the damping compounds and suspension materials of the drive units will take some time to recover their correct mechanical properties. The drive unit suspensions will also loosen up during the first hours of use. The time taken for the speaker to achieve its intended performance will vary depending on previous storage conditions and how it is used. As a guide, allow up to a week for the temperature effects to stabilise and 15 hours of average use for the mechanical parts to attain their intended design characteristics.
AFTERCARE
The cabinet surface usually only requires dusting. If you wish to use an aerosol cleaner, remove the grille first buy gently pulling it away from the cabinet. Spray onto the cleaning cloth, not directly onto the cabinet. The grille fabric may be cleaned with a normal clothes brush whilst the grille is detached from the cabinet.
Avoid touching the drive units, especially the tweeter, as damage may result.
