Sub bass Use (optional)
General Recommendations
The Sub bass section of the TDcontroller is monophonic (the Left and Right channels are summed at the
input of the Controller). In a Stereo sub bass installation using 2 TDcontrollers, bear in mind that when only
one Controller input is used, this will lower the gain of the Sub Output by -6 dB (as the nominal level is
calculated for a 2 input use). You can either increase the gain setting of the LSub with the front panel level
control or use a Y adapter to feed both inputs of the controller with the same signal. The PS15
TDcontroller MK2 also allows this setting to be made internally by moving jumper 4 (J4) to the “A” position.
(Seeon page 22)
For best results the LSubs should be positioned as close as possible to the PS loudspeakers and aligned
with respect to the audience. This helps to avoid interference near the crossover point.
Although sometimes in conflict with the above recommendation, LSubs' low frequency performance is
enhanced if multiple subs are grouped together. This also applies to Stereo installations using mono LSub
output where left and right Subs can be grouped together in the center for best effect.
The nominal efficiency data for LS400, LS500 and LS1200 and the standard Sub level settings on the
TDcontroller are for LSubs positioned on the floor (half-space). For other system configurations, and
particularly for « flying » subs, the low frequency sound pressure can be -3 to -6 dB lower. This can be
compensated for by a higher setting on the LSub output level control and/or by adding more sub bass
units.
Impedance Compensation Network (ICN) (PS15 Only)
The ICN feature is included in PS15 cabinets since
PS15 serial number 23853. Its main function is to
smooth the impedance curve of the HF driver, thus
improving the passive crossover. The direct result of
this circuit is to flatten the un-equalised response curve
(without TDcontroller) and to reduce distortion in the
1kHz-2kHz area. For compatibility with older
TDcontrollers see section « PS15TD MK2: Compatibility
with former PS15TD, LS1000 & PS15 cabinets » page
15. Please also note that this network is available as a
kit to upgrade older cabinets (and TDcontrollers).
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