9
in any optional headphones plugged in to the PHONES
connector located in the front panel jack field. If the
AFL/PFL MODE switch, located in the master section, is
switched out, the signal is sent pre fader, so you can hear
the signal regardless of the position of the channel vol-
ume Fader. This allows you to listen to a channel by itself:
(let's say) to see if an artist is out of tune, or to cue up a
channel without having to play it through the main PA
speakers. If the AFL/PFL MODE switch is switched in, the
signal is sent post fader, the signal you hear is dependant
on the position of the channel volume Fader. This allows
you to hear if there is any distortion on a channel added
by the level of the channel fader.
11- SOLO LED
The MDR1248 and MDR1688’s Mono Input channels
include a SOLO LED which, when illuminated, indicates
that the signal is assigned to the SOLO bus.
12 - PEAK LED
The MDR1248 and MDR1688’s MIC/LINE pre-amp also
includes a PEAK LED which, when illuminated, indicates
that the signal is peaking or overloading. To reduce dis-
tortion, lower the GAIN control to keep this LED from stay-
ing on.
13 - CHANNEL LEVEL
The MDR1248 and MDR1688’s LEVEL control knobs are
used to adjust the overall channel volume.
STEREO INPUT CHANNEL SECTION
The MDR1248 and MDR1688 feature stereo input chan-
nels for connected stereo line level devices like keyboards
and drum machines, as well as the outputs from effects
processors and digital guitar modelers. The MDR1248 has
four sets of stereo inputs which make up channels 5/6,
7/8, 9/10 and 11/12, while the MDR1688 has four sets of
stereo inputs which make up channels 9/10, 11/12, 13/14
and 15/16. The Stereo input channels have a four-band
fixed equalizer and AUX 1 and 2 sends and are laid out the
same as the mono inputs. The following section details
the stereo input controls:
14- GAIN switch
The MDR1248 and MDR1688’s pre-amp stage has a vari-
able GAIN switch with a range of -10 to +4dB on the ste-
reo LINE input.
15 - LOW/LOW MID/HIGH MID/HIGH - Channel
Equalizer
The MDR1248 and MDR1688 Stereo input channels fea-
ture a 4-band equalizer allowing you to adjust the high,
mid, and low frequencies independently on each channel.
The stereo channel equalizer is laid out like a mono input
on the control panel input strip, but internally, the equal-
izer is effecting a stereo signal path. The channel’s fre-
quency response is flat when the knobs are in the “12:00”
position. Rotating the knob towards the right will boost
the corresponding frequency band by 15dB, and rotating
Controls and Functions
it towards the left will cut the frequency by 15dB. The fre-
quency centers, range of boost or cut, and equalizer type
for each band are as follows:
High: 12kHz +/- 15dB shelving type
High Mid: 3kHz +/- 15dB peaking type
Low Mid: 500Hz +/- 15dB peaking type
Low: 80Hz +/- 15dB shelving type
