technically speaking
Loud, Louder and Loudest
Mention This Is Spinal Tap
around a group of musicians and they will declare
in unison, “This one goes
to eleven.” The mythical
British band in the movie
is enamored by a guitar amp with unprecedented volume capacity. So, too, it
appears, are many worship musicians.
A million dollars’ worth of acoustic
design, EASE and EARS modeling, meticulous installation and planning can
be obliterated by a single guitarist with
a tube amp. While increased volume is
ingrained in the fabric of modern worship music, there must be a reasonable
balance between the needs of the band
and the needs of the congregation. After
dozens of consultations with churches
about volume, I have developed a multipronged approach to giving the band
enough stage level to function properly
while reserving the bulk of the room’s
energy for the congregation. As Spock
noted in Star Trek III, “The needs of the
many (the congregation) outweigh the
needs of the few (the band).” Here then
are some guidelines:
The Five-Gallon Rule
The room will only contain a certain level before either it or the humans
occupying it express displeasure. Noted
acoustician R. Bob Adams conducted
an extensive study of the tipping point
where people begin to complain about
volume. R. Bob traveled to dozens of
churches and measured the music volume in the room. He then noted when
parishioners began to either leave or
complain about the level. After compensating in his study for the nature of the
venue and the genre of the music, he
correlated volume to comfort and tonality to involvement. He determined above
95dBA/slow, some portion of the congregation will find the level uncomfortable if it is maintained for more than one
minute. Below 95dBA/slow, few complaints are heard. Naturally, the context
of the music, the acoustic signature of
the room and the existence of aberrant
frequencies in the upper mids will affect the tipping point, but it is safe to use
95dBA/slow as a starting point for level
control. If the band’s amps, acoustic energy and floor monitors register 90dBA
before the mains are engaged, there is
a problem since the sound system has
only a 5dB window before the threshold is exceeded. The hapless engineer is
reduced to sending only vocals through
the mains and hoping for the best. In
this case, the band must reduce level as
there is no “silver bullet” solution available. The bucket is full before the PA is
turned on. Note, the level can go above
100dBA for short bursts without incidence; the concern here is the average
level over time.
On the issue of tonality, the human
ear-brain construct of smoothness is paramount to converting the listener into a
participant. R. Bob found a strong correlation between the phrase, “the band is
too loud” and an above average concentration of upper mid-band frequencies
in the octave from 2 KHz to 4 kHz. Since
the human perception of sound is focused (more sensitive) in the area around
3 KHz, any exaggerated or even slightly
increased level there will cause the listener to perceive the sound as “harsh.”
Unfortunately, many large format compression driver-based sound systems
used in churches exhibit a pronounced
intensity around 3 KHz. Therefore, one
of the easiest ways to improve the band’s
sound while reducing complaints is to
decrease the system’s response between
2 KHz and 4 KHz. The best approach is
to use a Loudspeaker Management System (LMS) like the Klark Teknik Helix,
with its adaptive equalization curve that
adjusts the EQ based on the current level
driven.
By Kent Morr is
The Invisible Sound Curtain
Sound does not magically stop at
the lip of the stage; it proceeds unencumbered into the audience. To illustrate,
if you walk into a home theater store
and ask the salesperson to demonstrate
the clarity of the speakers, the last thing
she would do is turn the speakers away
from you before engaging the Blu-Ray
disc. No one wants to hear the back of
the speaker, yet that is what we subject
the audience to each Sunday with our
floor monitors. Their boomy low-mid,
off-axis energy washes into the congregation and masks the clarity of the main
speakers while their time offset imbalance reduces the mix to mush. Additionally, guitar amps positioned on the stage
at floor level facing the audience sound
perfect to the guitarist but can devastate
the audience’s experience since they
receive an undue level from the amp’s
power alley.
The Audio Security Blanket
Performing in front of a congregation can be unnerving. Some artists use
a wall of sound as a security blanket to
protect themselves from rejection. Unfortunately, a pair of biamped wedges in
front of the leader is counterproductive
since it causes the BGVs to ask for more
level in their monitors; in turn the guitarist turns up his amp and the drummer
plays louder. It is a downward spiral. In
like manner, the FOH (Front Of House)
engineer can fall prey to the “louder is
better” mentality as one of the quickest
ways to improve the mix is to raise the
faders. It is a trap we must all avoid.
The Myth of In-Ears
In-ear monitors are not a panacea
for the band. They require a competent
engineer to develop the blend since the
wearer is now fully dependent on the
ears for the entire aural landscape. Floor
