Fine tuning, Running-in period | Bowers & Wilkins Signature 805

Should you not want to bi-wire, perhaps during the initial set-up procedure or because you do not want to see a multitude of cables in the room, short cables are provided to link both positive and both negative speaker terminals together.

When using the links, insert the spade into the slot in the side of one terminal and the crimped pin into the round side hole in the other. There is enough clearance to insert a spade connector from the amplifier into the same terminal as the crimped pin.

Ensure each positive terminal on the speaker (coloured red) is connected to the positive output terminal of the amplifier and negative (coloured black) to negative. Incorrect connection can result in poor imaging and loss of bass.

When bi-wiring, do not use the linking cables. Take extra care with the polarity of the connections as incorrect connection can also impair the frequency response through the bass-midrange crossover and, if the links are left in place, may cause damage to the amplifier by shorting its output terminals.

Fine tuning

Before fine tuning, double check that all the connections in the installation are correct and secure.

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 the 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 moving large pieces of furniture can have an effect.

If the central image is poor, try moving the speakers closer together or toeing them in so they point at or just in front of the listeners. (figure 4)

If the sound is too harsh, increase the amount of soft furnishing 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 shaped surfaces such as bookshelves and large pieces of furniture.

Ensure the speaker stands are firm on the floor. If you have a carpet, use carpet- piercing spikes and adjust them to take up any unevenness in the floor.

For the most discerning listening, remove the cloth covered grille as described below in the section “Aftercare”. The tweeter is very delicate and its grille should be left in position for protection. For this reason the grille retaining ring is designed to provide the optimum acoustic environment for the unit and the response is less smooth with the grille removed.

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

60 hours of average use for the mechanical parts to attain their intended design characteristics.

Ancillary equipment

Speakers of this ability deserve signals of the highest quality. Choose your electronic equipment and interconnecting cables with care. We can give guidance on what to look for when choosing ancillary equipment, but cannot recommend specific items. The standards of such products are improving all the time and your dealer will be able to demonstrate a variety of suitable up-to-date products.

In the specification we recommend a range of amplifier powers. The higher figure is defined by the power handling capability of the speaker. When calculating the power handling, it is assumed that the amplifier is not run into clipping, which distorts the frequency power spectrum of the signal, and that the signal is normal programme material. Test tones from oscillators and the like are not applicable. The lower figure is the minimum we consider necessary to achieve reasonable listening levels without audible distortion in the smaller room (less than 50 m3 or 2000 cu ft). The higher the power you use, the less likely you are to experience amplifier clipping. You can often tell how good an amplifier is at driving complex speaker loads by looking at its power rating into both 4Ω and 8Ω loads. The nearer the ratio is to 2:1 the better, as it indicates a good current capability.

In order to reduce the effect the cable has on the frequency response of the speaker to inaudible levels, the impedance of the cable at all frequencies (measuring both positive and negative conductors in series) should be kept as low as possible and certainly below 0.1Ω. At low frequencies, the DC resistance of the cable is the dominant factor and you should choose a gauge of wire sufficient to achieve the impedance requirements over the length of cable you need to use. At mid and high frequencies the inductive component of the impedance can dominate the DC resistance. This and other properties influenced by the detailed construction of the cable become important. Ask your dealer for advice on the best cable for your needs.

Aftercare

The cabinet surface usually only requires dusting. 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.

The surface of the tweeter housing will benefit from the use of an anti-static cleaner. Do not attempt to remove the tweeter grille.

Avoid touching the drive unit diaphragms, especially the tweeter, as damage may result.