Focal BombA 27 V1, Руководство пользователя

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Connecting up
Always check the polarity to the subwoofer, and that of the other speakers used in your
installation. The polarity is important to ensure the phase characteristics remain correct,
otherwise a "loss" of performance can result. The spring action input terminals are clearly
marked red spot = positive (+) and black spot = negative (-).
These subwoofers can be mounted in the traditional sense with the membrane on view
externally, or inverted mounting with the motor unit and its chrome back plate on display.
Inverted mounting helps increasing the volume for the given space available. When choosing
inverted mounting the phase must be inverted (thus swap the positive / to negative connections)
so that the polarity is correctly observed.
Multi-subwoofer installations
To obtain a more powerful acoustic presence, we recommend the introduction of multiple
subwoofers for your chosen installation. Using multiple subwoofers, various series or parallel
or combinations of both can be used, but always check the specifications of the power source
(amplifier) before attempting any installation. It is worth remembering if low impedance of 2 or
even 1 ohm is chosen an amplifier of high quality should always be used for such installation.
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 (+).
Calculation of the impedance is (Z), for the given impedance value nominal (R), is 4 ohms.
• 2 subwoofers : 1/Z = 1/R1 + 1/R2 1/Z = 1/4 + 1/4 Z= 2 Ω
• 3 subwoofers : 1/Z = 1/R1 + 1/R2 + 1/R3 Z = 1,33 Ω
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.
Thus the positive (+) of 1st subwoofer will be connected to the positive (+) of the amplifier.
The negative (-) of the 1st subwoofer will be connected to the positive (+) of the 2nd subwoofer.
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.
Calculation of the impedance is (Z), for the given impedance value nominal (R), is 4 ohms.
• 2 subwoofers : Z = R1 + R2 Z = 4Ω + 4Ω Z = 8Ω
Polyglass Subwoofers Manual
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notice sub v1 2 17/10/06, 11:37:22