Lowell EQ1 - Manual (Page 7)

Instruction Sheet
IS-EQ1
Issued: 1-20-14
Lowell Manufacturing Company 100 Integram Drive Pacific, Missouri 63069 U.S.A.
Call: 800-325-9660 Fax: 636-257-6606 Click: www.lowellmfg.com
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An EQ1 can be used for tone contouring by ear which is basically adjusting the tone of the system. Be careful
about adding upper bass (63 Hz to 200 Hz)
as this can cause “muddiness” or loss of definition. Also see the
previous warning about boosting frequencies below 63 Hz. Middle frequency problems usually express them-
selves by vocals having a nasal quality (too much mid band boost) or vocals not being easily understandable
(usually caused by mid band frequencies being under represented in the overall sound).
It’s good for a sound
system to have a crisp sound in the high frequency bands, but too much high band energy can cause vocal
speech or singing to sound too “spitty” or “essy”. Boosted highs can cause too much “sizzle” in music which can
be most obvious if the music includes cymbals and hi-hats. Be careful voicing a system by ear. This takes a lot
of experience and poor choices can result in feedback and in an unnatural sounding system.
It is important for a graphic equalizer user to understand the limitations of this technology. Acoustic problems
are generally not consistent across the entire area of the sound system coverage. This is much more of a
problem when setting up a sound system for a large venue. In a typical large room or hall, there will be areas
that have acoustic reinforcement and resonance problems and other areas where certain frequencies are
almost entirely canceled out.
It’s always a good idea to try to seek an acoustic remedy for acoustic problems
whenever possible. When this is not possible or feasible, an equalizer may be used to compensate for an
acoustic problem. But the problem is only improved at the point where the measurement is taken and other
locations in the room may be adversely affected by the equalizer setting. For this reason, it is a good idea to
measure the acoustic response of the system from several locations and average the equalizer’s setting. Doing
this helps most locations in the venue to receive similar acceptable sound quality from the sound system.
Equalization can be like spice in the hands of a master chef. A little goes a long way in improving sound quality,
too much, and the mix is spoiled. If modest amounts of equalization (6-8 dB) do not solve the problem, it is best
remedied by other means. Avoid adding large amounts of boost below 63 Hz, especially when using vented
bass cabinets.
Boosting frequencies below the vented enclosure’s low frequency cutoff can easily cause over
excursion of the speaker’s cone, causing premature failure. In addition, boosting low frequencies can make
your power amplifier run hotter, leading to premature amplifier failure. Boosting high frequencies can
sometimes emphasize the high frequency noise from the electronic equipment in the sound system signal chain
and a “hiss” may be heard coming from the speakers. Be conservative boosting frequency bands when
equalizing a sound system. When equalizer adjustment is completed, compare the un-equalized sound with the
equalized sound by alternately engaging the BYPASS switch. Use familiar source material and walk around in
the sound coverage area to insure that no anomalies have been introduced into the sound in the listening area.
If it sounds good,
you’re done.
Live Microphones and Controlling “Feedback” using the EQ1
We’ve all heard that annoying squeal when live microphones are used and the sound system goes into
“feedback”. No matter how perfectly you have set your EQ1 to flatten the frequency response of the sound
system, there will still be some peaks at certain frequencies. When a sound system is turned up to the point
that the output of the speakers is picked up again by the microphone and re-amplified, the frequencies where
there are peaks,
will “ring” or “squeal” first. In some cases the sound system’s gain before feedback will not let
the operator turn up the sound system loud enough for the needs of the performance. When the sound system
is turned up with the live microphone turned on until feedback occurs, the frequency that feeds back will show
up as a spike on the display of a real time analyzer (RTA). If the feedback is at an isolated frequency, it is
possible to slightly lower the gain of the slider on the EQ1 in the 1/3 octave band that contains that frequency.
Note that when you tune out that feedback, you are also reducing the level of all of the frequencies in that third
octave band, so notch for feedback sparingly. Notching too many sliders to reduce feedback can make the
sound system sound terrible.
It’s best to listen to the system after each adjustment to make sure you haven’t
overdone it. When 3 or 4 frequencies are feeding back at the same time, that means the output of the system is
fairly flat so you should stop.
You’ve now gotten as much volume out of the sound system as possible unless
you change the location of the microphone, or change the aiming of the speakers to keep the sound from the
speaker from being picked up by the microphone. If the sound system can now be operated at a louder level
because you have reduced the feedback and the system still sounds good,
you’re done tuning for feedback.
Tone Contouring ( Also called “Voicing”) using the EQ1