Apogee APL-220, Руководство пользователя

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(8) Level Control
A single level control is located just above the XLR input. Under normal cir-
cumstances, the level control should be turned fully clockwise to the 0 posi-
tion. This is full gain, or 0 dB of attenuation. In certain environments, for
example, very quiet productions, it may be desirable to reduce the gain of the
powered speaker to improve the overall gain structure of the entire audio
system and possibly reduce system noise slightly. This is easily achieved by
turning the level down to the desired amount of attenuation.
When multiple speakers will be attenuated, it is best to count the detent
positions as the level control is adjusted. By doing this, you will be able to
accurately set each speaker to exactly the same attenuation.
It is important to confirm that the level is set appropriately before deploying
the speaker into a location where it will be difficult to reach.
(9) Mute Control
Each channel of the internal amplifier has a user accessible mute button.
Muting the high frequency or low frequency amplifier output can be useful in
troubleshooting a system. The two buttons are labeled Ch
1
and Ch2.
Channel
1
is the high frequency amp and Channel 2 is the low. Mute is
enabled when the button is out. It is important to confirm that both buttons
are depressed (un-muted) before deploying the speaker into a location
where it will be difficult to reach in order to un-mute a channel.
(
1
0) Indicators
The APL-220, -500, and -800 have a green LED labeled PWR (Power) that
indicates AC mains power is applied and the power supplies are functioning
properly. A green Signal LED is above the level control. An amber LED just
above the power LED indicates clipping. A red LED labeled PROT (Protect)
is provided to indicate that the amplifier has gone into protect mode. Protect
mode occurs under the following conditions:
(a) The amplifier has exceeded its maximum safe operating temperature (the
amplifier will automatically reset after cooling down).
(b) The amplifier has failed and is outputting DC voltages that could damage
the driver(s), or DC is present upstream of the amplifier due to component
failure in the processor.
(c) The driver(s) may have failed causing the amplifier to produce excessive
output voltage.
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