User manual B&W CM4

[. . . ] To validate your warranty, you will need to produce this warranty booklet completed and stamped by your dealer on the date of purchase. Alternatively, you will need the original sales invoice or other proof of ownership and date of purchase. 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. [. . . ] 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 use 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 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. When biwiring, incorrect connection can also impair the frequency response. [. . . ] 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. If you wish to use an aerosol cleaner, remove the grille first by 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. [. . . ]