FBT QUBE PA - Manual (Page 12)

AMPLIFIER SETUP AND OPERATION
Amplifier setup and operation
Mounting
Cooling
Wire size
Verification of proper operation
The amplifiers are designed to be mounted in standard 19” racks. They have 4 front panel mounting screws. Because of their
depth and weight it is imperative that the amplifier be supported at the rear in any portable application.
Both amplifiers are fan cooled and it is important that an ample supply of air is provided at the front of the amplifier and a free air
exhaust space is provided at the rear of the amplifier. The internal fan provides adequate cooling when the rack has an open
back and the front is not obstructed. Closed back racks may need to be pressurized and provided with an exhaust fan to
ensure adequate air movement.
Multiple amplifiers may be stacked directly on top of each other. Their is no need to separate them with a blank (spacer) panel.
Keep in mind that almost all amplifiers radiate a 50/60Hz magnetic hum field from their power transformers. It is prudent to
provide at least one rack-space between any signal processing equipment and the nearest amplifier to reduce the possibility
of induced hum.
The size of the speaker wiring needed depends on the lenght of the cable. We generally recommend the use of 12 AWG for
cables up to 30 meters (approximately 100 feet) in lenght. The following table shows the signal loss in 30 meters of cable
driving a 4 ohm load:
Wire Gauge (AWG) 10 12 14 16 18
Signal Loss (dB) .44 .69 1.07 1.65 2.49
Using higher wattage amplifiers than actually needed is acceptable when controller modules are used as the controller will
keep peak power levels within the acceptable limits for the associated loudspeaker(s).
Before applying power to the system, trace and verify all connections.
Make certain all the Mode selector switches are set in the desired mode and that outputs are properly connected.
Loudspeaker damage may occur if, for example, the Sub outputs are connected to the high frequency drivers and not to the
Subs!
Set the power amplifier gain controls to their minimum position.
Turn on the power amplifiers and slowly turn the amplifier level controls to their maximum position one at a time. While you are
doing this, verify that as the amplifier gain is increased the appropriate response is obtained (i.e. the sub channel is connected
to the subwoofers).Moderate level audio should be heard from the loudspeakers.
Gradually increase the signal level while observing the signal LED’s. As the level increases they should begin to flicker red. As
the level continues to increase they will be on for longer periods of time.
If as you are increasing the level, you hear a sudden loss of one channel and see illumination of a red Status LED, this
indicates one of the amplifiers protective circuits has been activated. Turn the amplifier off, reduce the gain and then turn the
amplifier on again.
Caution: operating the system at full level can damage your hearing. Wear ear protectors and do not position yourself in front
of the loudspeakers.
Do not operate the system at a level where the
protection LED’s are illuminated continuously.