Rane MM 12 - Manual (Page 11)

2. Set both BASS and TREBLE boost/cut knobs to the ”0” center detent position, and
both BANDWIDTH buttons to the NAR (in) position.
3. Slowly turn up both the #1 MASTER level and the MIX LEVEL knob in column 1 for the
microphone located next to monitor 8 on stage: turn up both level controls until
feedback begins to occur.
4. If the feedback tone is high in pitch, start with the TREBLE adjustments: if the tone is
low in pitch, start with the BASS adjustments. In this example we’ll assume you get a high-
pitched squeal first, since this is more common.
5. Turn the TREBLE BOOST/CUT control to full CUT (counter clockwise) position.
6. Now sweep the TREBLE FREQUENCY knob from full counter clockwise to full
clockwise (1k Hz to 10k Hz) slowly, while keeping the master volume in the monitor
speaker at a point where feedback is occuring but not loudly out of control (this takes a
cool head and a supple wrist). You will notice a point on the sweep control where the
feedback will be reduced or stop altogether: this is the center frequency of the
feedback
7. Now that you have found the center frequency, leave the SWEEP knob set at this
point. Then slowly turn the BOOST/CUT knob clockwise until feedback begins to re-
occur: set the BOOST/CUT control at a point where feedback just goes away. Too much
cut will detract from the sound quality of the monitor and render the monitor program
harder to understand. If feedback occurs later at a higher volume level, m-adjust the
BOOST/CUT control just enough to eliminate the feedbackand no more. Don’t readjust
the center frequency control as it is difficult to find the feedback center frequency during
a show without embarrassing feedback
8. Now repeat steps 5, 6 and 7 with the BASS section of the channel 1 parametric
equalizer. You will notice that after one feedback tone is eliminated, increasing the
volume will produce another tone of a different pitch. You could chase these tones ”ad
infinitum”, but a good working compromise is to reduce the two primary feedback
trouble tones, so that you have a system that feeds back at a much higher level with two or
more different tones. Repeat steps 5 through 8 with output channels 2 through 6 as
necessary.
In some cases, the acoustics of the stage or the performance of the monitor speakers is
such that feedback is not a real problem, but that the overall monitor sound is lacking in
quality and is therefore more difficult to understand. If the bass response of the monitor
is poor, use the BASS section of the parametric to boost the low end; try both the NARrow
and WIDE bandwidth positions-too much low end boost can result in boomy response
that muddies up monitor sound. If presence is lacking in the monitors, use the parametric
TREBLE section to add response in the high end. In either case, startingwith full boost and
sweeping the frequency will help you to find the right area to correct: once found, cut
back on the boost as necessary to give the smoothest overall response.
IV-4. USING THE MM 12 HEADPHONE CUE SYSTEM. It is much more effectiveto use the
CUE system to make adjustments in the monitors, especially during a performance. By
depressing the appropriate CUE button you can listen to the exact mix that each performer is
hearing and make adjustments by ear rather than by guesswork
A. PATCHING INTO THE MAIN MIX CUE SYSTEM. In many cases the MM 12 will be
operated along side the house mixer by the same operator. As shown in the installation
diagrams, be sure to plug the headphone output of the main mixer into the MAINS INPUT of
the MM 12 headphone section, using a STEREO 1/4” shielded patch cord. Then plug a single