JBL Synthesis K2 S9900 - Manual (Page 30)

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Presence Level
This switch adjusts the attenuation applied to the 476Mg driver by approximately
0.3dB over the range of 1,500Hz to 3,000Hz. The vocal presence range is made
softer by reducing the level and stronger by increasing the level. This action is
accomplished by trimming attenuation resistors. No additional parts are inserted
in the signal path and there is no sonic deterioration caused by use of the control
(Fig. 11).
Figure 11. Adjustment range of the presence-level control. Upper band indicates
+0.5dB and lower band indicates –0.5dB.
Bi-Amp Switch
The bi-amp switch is located under the battery access cover and allows the
system to be set up for the use of an external low-level crossover. This switch
removes the passive components in the low- and high-frequency networks that
have to do with the actual crossover blending of the low-frequency and high-
frequency transducers. Level attenuation and equalization circuits remain active.
In the case of the K2 S9900, the voltage drive required from an external
crossover network is very unusual and, in most cases, is not likely to be achiev-
able with standard crossover networks. It is for this reason that active bi-amplifi-
cation of the K2 S9900 is not advised (Fig. 12).