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On the processing unit, you will use the mixed signal output to return the signals (both wet and dry) to
the return jack on the amplifier. The ratio between the wet signal and the dry signal is heard as the
amount of effects added back to the original signal, which is controlled by the mix knob (also called
“balance”) on the effects processor. This may be a real knob (as in the Alesis Microverb), or software
controlled (as in the Yamaha SPX-90, SPX900 or SPX 990). Set the input sensitivity on the effects proc-
essor according to the processor manufacturer’s instructions. The “
effects send jack”
may also be used
as an auxiliary output to drive a direct box, tape deck etc. This output is pre-equalization, and pre master
volume. The “
mute switch”
will shut this output down when engaged.
Master Volume —
The “
master volume control”
is post-eq, and adjusts the signal level sent to the
power amplifier. Best results are usually obtained when this control is set between the 9 o’clock and 3
o’clock position.
Master Section Status Indicators —
•
The “
power LED”
indicates that the amplifier is on and the low voltage regulated power supplies are
active.
•
The “
protect LED”
indicates that the amplifier is in “protect” mode and the output relay is de-
energized. This LED will illuminate for approximately 3 seconds during power switch-on and switch-
off. It is normal for this LED to glow while continuing to monitor the internal conditions for about 3
seconds after the protection relay has closed. It will also illuminate during any internal fault condi-
tion. If this happens, turn the amp off and consult a repair technician.
•
The “
thermal LED”
indicates that the amplifier has overheated, engaged the protection circuit and
shut down. This circuit is self-resetting when the offending condition (blocked air vents, foreign body
stuck in fan, etc) is corrected. This LED will also flash for a brief time at turn-on and turn-off, indicat-
ing that the amplifier protection circuits are operating. This LED will illuminate about 15 degrees F.
before amplifier shut-down.
•
The “
signal LED”
indicates that the power amplifier is receiving signal (over several watts output)
and all is well!
•
The “
limit LED”
indicates that the power amplifier has reached maximum power and the limiter
threshold has been crossed. Driving 6dB beyond this point, the amplifier will gradually begin to clip.
•
The “
output limit switch”
engages or bypasses
the internal soft clip limiter. This limiter allows simula-
tion of output saturation as the amplifier nears its maximum power. The limiting action is particularly
musical sounding, even when driven hard.
Direct Output —
The
GBE 400
includes a studio quality, fully active transformerless balanced “
direct
output”
, with “
pre-post equalization switch”
.
With the “
pre/post switch”
in the “pre” position, the direct output receives its signal directly from the pre-
amp input buffer amplifier with no tonal modifications. This is a pre gain control, pre eq output, with the
best signal to noise ratio. Most recording and sound reinforcement companies will want to use this posi-
tion since changes you make to your stage sound will not affect this output.
With the “
pre/post switch”
in the “post” position, the direct output receives its signal from the output of
the 5 band equalizer. This feature allows for additional flexibility in some situations, but is often not de-
sired for recording or live sound reinforcement.
A “
ground lift switch”
is provided which opens pin 1 (shield) on the direct output to prevent ground loops.
Use the position that results in a minimum of noise.
