User manual FOCAL SUBWOOFERS POLYGLASS

[. . . ] If not followed correctly any fault observed, may not be covered by the guarantee. The improved power handling has allowed Focal subwoofers to play at very loud sound volumes. For this reason, we recommend caution be wisely applied, especially during long listening periods. Excessive volume levels of more than 110dB can cause permanent hearing damage. [. . . ] connections in parallel Normally the terminal positive (+) on the subwoofer will be connected to the equally marked positive (+) on the amplifier , and the terminal negative (-) on the subwoofer to the equally marked negative (-) on the amplifier. Only on an inverted subwoofer installation is it normally necessary to invert the connections (-) and (+). 3 subwoofers : 1/Z = 1/R1 + 1/R2 + 1/R3 Z = 1, 33 Connections in series Using multiples of subwoofers for such comprehensive installations, it is sometimes better to connect them together in a series circuit. Using a low impedance load to the amplifier effectively ensures it will work less hard. For connecting the subwoofers, they are effectively looped together in any series circuit. Then depending on how many subwoofers are to be included this looping will continue, until the last (in this basic case the 2nd subwoofer), will have its negative (-) connected to the negative (-) of the amplifier. Connections series and parallel, combined Depending on your installation amplifier(s), subwoofer(s), various combinations of series and parallel circuits can be used. The real advantage of doing this is to have a system with available power, but at the same time to ensure the system impedance load is optimum for the amplifier(s) used. Adjustment of low cut off frequency The cut off frequency of a subwoofer is normally in the region of 60 to 100Hz. This is always dependent on the particular installation and listening position. A frequency of 80Hz is a good compromise for effective bass compared to listening quality. If you decide to `brew your own', it is safest to go for a bass-reflex type. This classic simple alignment usually give the best and most consistent results. See below regarding our proposals for the various volumes available per subwoofer. Vented boxes A bass-reflex system is more efficient than the sealed box since some of the energy from the rear of the cone is converted via the reflex port to add in phase with the main output. There is also a reduction of cone travel at the tuning frequency, so this system can also give higher power handling. You can make a vent port from a piece of plastic pipe, or there are many profiled vent custom designed for loudspeakers that minimize turbulence (prevents what's commonly referred to as chuffing). Building an enclosure The construction should always remain strong and rigid, to eliminate any unwanted resonances. [. . . ] A safe guide is to ensure the maximum power of the amplifier is not greater than the nominal power of the speakers. Guarantee All Focal loudspeakers are covered by guarantee drawn up by the official Focal distributor in your country. Your distributor can provide all details concerning the conditions of guarantee. Guarantee cover extends at least to that granted by the legal guarantee in force in the country where the original purchase invoice was issued. [. . . ]