Setting The Mode Switches; Setting Clip Limiters; Selecting Stereo, Parallel, Or Bridge Mode; Setting Low Frequency Filters - QSC CX Serie Manual De Instrucciones

Setting the Mode Switches

Figure 5 is a typical Mode Switch block as seen from the rear of the amplifier (CX404V model shown).
Two-Channel Models: One mode switch controls each channel's independent clip limiting and low frequency (LF)
filtering. The switches can set the amplifier's operating mode for Stereo, Parallel, or Bridge operation.
Four-Channel Models: There are two mode switches; one controls the operation of channels 1-2, the other controls
the operation of channels 3-4. It is not possible to bridge or parallel channels 1 or 2 with channels 3 or 4.

Setting Clip Limiters

Each channel has a clip limiter with its own on-off switch. The limiter only responds to actual clipping, and automatically
compensates for load and voltage variations. Clip limiting is generally recommended, especially to protect high frequency
drivers. (Figure 6)
• Set switch UP (ON position) to use Clip Limiting.
• Switch 1 controls the first channel.
• Switch 10 controls the second channel.

Selecting Stereo, Parallel, or Bridge Mode

Each of the channel pairs can be set for normal Stereo operation, Parallel Input mode, or Bridge Mono mode. On four-channel models, Ch.1 can be
bridged or paralleled with Ch.2; Ch.3 can be bridged or paralleled with Ch.4.
Stereo Mode: Each channel within the pair remains independent, and each may be used for a different signal. Switches
4, 5, 6 and 7 are all set to the DOWN position.
Parallel Mode: This setting connects both inputs of a pair together. One signal feeds both channels. Do not connect
different sources to each input. Each channel's Gain control and speaker connection remain independent. Switches 4, 5,
and 6 are set to the UP position. Switch 7 is set to the DOWN position.
Bridge Mode: This setting combines both channels of a pair into a single channel with twice the output voltage. Use
only the first channel's input and Gain control. Set the second channel's Gain control at minimum. Switches 4, 5, 6 and 7
are all set to the UP position. (Figure 9)
NOTE: Do not connect different inputs to each side of a channel pair when operating in parallel or
bridge mode.

Setting Low Frequency Filters

Each channel has a 12dB per octave Low Frequency filter that can be set on or off. Low impedance models can be set
for 33 or 75 Hertz and distributed output ("V" models) for 50 or 75 Hertz to prevent saturation of the 70V speaker
transformers. This reduces distortion and prevents amplifier overload.
• The first channel uses switches 2,3. The second channel uses switches 8,9.
• Switches 3 and 8 turn the LF filter ON or OFF.
• Switches 2 and 9 select 33/75 Hz (low Z) or 50/75 Hz ("V" models) or 75 Hz.
• On four-channel models, the second mode switch has switches for Ch.3 and Ch.4
Low Impedance Models: The filter should only be turned off for driving subwoofers. The 33 Hz setting usually works well with loudspeakers that
have large LF drivers (12" or larger). The 75 Hz setting works well with compact (smaller size) loudspeakers. Check the loudspeaker's specifications
and select the setting closest to the loudspeaker's low frequency capability.
High Impedance ("V") Models: The filter should only be turned off for driving subwoofers with special low frequency transformers. The 50 Hz
setting usually works well with high quality speaker transformers. The 75 Hz setting works well with speech-grade speakers and transformers.
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