Altec Lansing 1662A - Manual (Page 4)

4
Operating Manual -1662A Mic/Line Mixer
4. FRONT P 4. FRONT P 4. FRONT P 4. FRONT P 4. FRONT PANEL CONTROLS ANEL CONTROLS ANEL CONTROLS ANEL CONTROLS ANEL CONTROLS
4.1 Input Gain 4.1 Input Gain 4.1 Input Gain 4.1 Input Gain 4.1 Input Gain S w i t c h S w i t c h S w i t c h S w i t c h S w i t c h
This three position switch sets the
operating level of the input preamp to +20db,
+40dB, or +60dB. Best signal to noise ratio is
obtained with higher gain settings. It is
therefore desirable to set the gain switch as high
as possible while still leaving 20dB of headroom
for signal peaks. Line level inputs will likely use
a setting of +20dB, while mic inputs generally
require a setting of +40dB for close mic
applications, and +60dB for quieter signals. If a
channel's clip LED is blinking, first turn down
that channel's level control. If the clip LED is
still flashing, turn down the input gain.
4.2 Clip Indicator 4.2 Clip Indicator 4.2 Clip Indicator 4.2 Clip Indicator 4.2 Clip Indicator
Input Clip LEDs are peak sensitive and
monitor all critical points within the input
channel. The clip LED turns on whenever any
portion of the audio path within the input
channel reaches a level 3 dB below actual
clipping. Clipping in the 1662A occurs at +23dB.
4.3 T 4.3 T 4.3 T 4.3 T 4.3 Trrrrreble and Bass Contr eble and Bass Contr eble and Bass Contr eble and Bass Contr eble and Bass Contro l s o l s o l s o l s o l s
These controls are used for broad EQ
changes to each input channel. Channel EQ
consists of a high shelf control (treble) at 8KHz,
and a 90Hz low shelf control (bass). EQ boost or
cut is ±12dB at these frequencies.
4.4 Input Assign Switch 4.4 Input Assign Switch 4.4 Input Assign Switch 4.4 Input Assign Switch 4.4 Input Assign Switch
This switch selects the output routing for
each input channel. Each input can be routed to
Output A, B, or both.
4.5 Input Level Contr 4.5 Input Level Contr 4.5 Input Level Contr 4.5 Input Level Contr 4.5 Input Level Contro l o l o l o l o l
This knob adjusts the level of each
channel. If a channel's level control is always
turned up to 9 or more, try increasing the gain
first. Conversely, if the level control is
consistently turned down to 1 or less, decrease
the gain setting first. Remember that the gain
setting should be set as high as possible while
still allowing 20dB of headroom.
4.6 Output Level Contr 4.6 Output Level Contr 4.6 Output Level Contr 4.6 Output Level Contr 4.6 Output Level Contro l s o l s o l s o l s o l s
These two controls determine the signal
level to the "A" and "B" outputs. They are used
to drive power amplifiers for the main
loudspeakers, or to connect to a stereo
recording device.
4.7 Output Meters 4.7 Output Meters 4.7 Output Meters 4.7 Output Meters 4.7 Output Meters
A pair of peak reading 11 segment LED
meters are used to indicate stereo output level
in VU. 0 VU is equivalent to +4 dBu (1.228Vrms).
Green LED's are used below 0 VU, yellow
above 0 VU and two red LED's indicate clipping.
The clip LED's turn on 3dB below actual