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9.
ЕОСЦР
This red LED turns on when the post-EQ signal level is 3 dB below clipping, warning
to decrease the EQ boost and/or to turn down the signal level at the channel input gain
stage. Clipping at this stage can occur even though the input signal is not clipping, due
to boost (gain) applied with the EQ circuitry.
10. 20 ~ 400 Hz (Н.Р. filter)
This rotary control sweeps the cutoff frequency of a high pass filter (low cut) from 20
Hz to 400 Hz. The filter slope is 12 dB/octave.
Typical applications include cutting wind noise, vocal "P" pops, stage rumble, and
low frequency leakage from adjacent instruments. Higher frequency settings can be
used to reduce leakage into mics that are primarily handling high-frequency sources.
In general, it is a good practice to use the filter to protect woofers from unnecessary
over-excursion due to the presence of unneeded low frequency or sub-sonic compo-
nents, especially if a microphone is dropped or kicked; the filter should be bypassed
(switch up) only when low frequencies are intentionally sought, as with a synthesizer,
drum, bass guitar, and so forth.
11. (H.P. filter In/Out switch)
This locking switch activates the input channel HIGH PASS FILTER (switch in) or
bypasses it. This filter bypass function is independent of the EQ section, which has its
own bypass switch.
12. AUX 1, AUX 2 (Send Level & Pre/Off/Post Switches)
There are 2 rotary AUX send level controls with concentric PRE/OFF/POST switches.
The switch mutes (turns off) the send, or derives signal before (PRE) or after (POST)
the channel Fader and EQ. The associated rotary control determines how much of the
selected signal source is applied to the correspondingly numbered auxiliary mixing
bus. When the switch is in the center (OFF) position, no signal is applied to the auxiliary
bus. (See Note below the AUX 3/4, AUX 5/6 description.)
13. AUX 3/4, AUX 5/6 (Send Level)
In order to provide the maximum number of auxiliary busses in the available space,
these four send level controls are arranged in two concentric pairs: AUX 3/AUX 4, and
AUX 5/AUX 6. These sends are factory wired to be pre EQ and Fader, and thus operate
identically to the AUX 1 or AUX 2 sends when they are set to PRE mode. However, in-
ternal jumpers are provided for each of these four sends (Aux 3 to 6) which enable them
to be individually changed so they are POST EQ and Fader.
NOTE:
Іп some applications, it is preferable to have the PRE mode be Pre-Fader & Post-EQ
rather than Pre-Fader 8 Pre-EQ as these consoles are shipped. The PM1800 is equipped
with an internal jumper on each channel that makes it easy to change the "Pre" of all
six of the channel's AUX sends in this manner. This functional modification can be
performed on a channel-by-channel basis. Refer to the OPTIONAL FUNCTIONS section
of this manual for additional information.
14.
+48V
This switch turns phantom power on and off at the channel's XLR input connector.
Power can be turned on, however, only if the MASTER PHANTOM POWER switch is
on.
When both the Master and this switch are on, +48 volts is applied to both pins 2
& 3 of the channel input XLR connector, via 6.8 kohms isolation/current limiting re-
sistors, for remote powering of condenser microphones.
Although phantom power
will not harm most dynamic and other non-phantom powered microphones or line-level
devices, connection of an unbalanced source to the channel input could partially short
the console's phantom supply, cause undue loading, and induce hum. Therefore, it
is a good practice to turn off the channel's phantom power unless it is actually in use.
NOTE:
The console's microphone power supply is not intended for A-B powered micro-
phones. External supplies may be used with these devices, in which case the console's
phantom power should be turned OFF on the appropriate channels. The optional input
transformers, if installed, do not affect phantom power operation.
2-3
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