VARIABLE Q
The operation of a subwoofer (or any
dBSubwoofer Operating Range
95
moving-coil loudspeaker) is divided
into two regions. Below resonance,OPERATING RANGE
90
where the motion of the cone is RESONANCE (Fs)
Ostiffness-controlled,� the subwooferOs
85
suspension does a great deal of the
MASS-CONTROLLED
work of opposing the inertia of the
moving assembly � the stiffness of 80
STIFFNESS-CONTROLLED
the suspension controls the motion
of the cone. Above resonance, where75
the motion of the cone is Omass-
controlled,� the subwooferOs 70
suspension has little effect on the
motion of the cone, and the motor65
must do all the work of opposing the
inertia of the moving assembly � the
60
motor controls the motion of the cone.
OOpposing inertia� simply means
55
starting and stopping the motion of 20Frequency50100Hz2005001K2K
the cone.
Figure 2. Subwoofer operating range.
The metal inserts included with your
Kappa Perfect VQ Series woofer are
used to adjust the amount of force the
motor can exert on the inertia of the
moving assembly. The largest of the
two inserts (LowQ), when installed in
the wooferOs polepiece, will provide
the highest motor force and, conse-
quently, the lowest Q (see Figure 3).
The smaller of the two inserts (MidQ)
will provide less motor force and
somewhat higher Q and the woofer
used without an insert will have a
much higher Q. (continued)
Figure 3.
3 |