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This month's article is fourth in a series about setting
up a sound system for live playing. Previously we discussed
the operation of an analog mixing board and also discussed
live sound myths. These articles are in the Metro Music
Mayhem archive and I recommend to read them first.
SPEAKER PLACEMENT
Let's say we are a band and have arrived at the venue
where we are playing. The equipment is unloaded and
ready to be set up. We are ready to place the speakers
used for the PA system. Most venues provide a stage
to be used which dictates the placement of the speakers.
It seems placement of the stage in most venues is rarely
given consideration to aid in producing good sound.
It also always seemed during my time on the road that
anytime we returned to a venue that had "renovated"
it meant they made the stage smaller and moved it to
an even worse location for sound and visuals. But we
can control a few variables concerning speaker placement.
First of all the speakers need to be on either side
of the stage and forward of the microphones on stage.
This will minimize feedback in a large way. Second,
it is extremely beneficial to have any speakers producing
bass on the floor. It may look better to put the speakers
on the stage, but the benefit of having the floor become
an actual part of the speakers enclosure is lost. Moving
the speakers even slightly off the ground drastically
reduces the amount of volume you will get in the lowest
octave being amplified. In order to restore it you will
have to increase its level by boosting the EQ on those
frequencies. Remember if we lose even 3 db of level
then it will take double the amplifier power to make
up for it.Your system may not support this and cause
amplifiers to distort and speakers to blow. One other
note about bass response. The size and shape of the
room and the composition of the floor also have much
bearing on how much bass you will get. Some rooms that
are more square or rectangular may suffer from standing
waves. These are reflections of sound that come back
out of phase and will cause bass dropouts in some areas
and reinforcement in others. Also a wood floor will
resonate sympathetically with the bass reinforcing it
as opposed to a concrete floor which will not. These
are all variables a lot of people don't take into account
and they can't figure out why they have so much low
end in one venue and none in another using the same
sound system.
According to the room setup of a venue and the type
of event, there are other considerations for the configuration
of the speaker system. Will people be sitting down as
in a concert type situation or will they be moving about
and possibly standing and watching near the stage? Obviously
in a sit down situation you can stack all speakers on
the floor and control the coverage of the listening
area. In a situation where people are moving about it
may be beneficial to raise the speakers above the audience's
head to cover the room. Some systems like the Mackie
SRM series have poles that fit in the subwoofer to mount
the mid/hi speaker on .Other systems have stands to
mount the mid/high speakers on and the subwoofers are
placed near them on the floor. In a system where the
crossover point for the subwoofer extends into the low
mids, you should keep the voice coils of the mid/hi
speakers in line to insure time alignment of all frequencies
produced. If a true subwoofer is being used and crossing
over in the 100 HZ area voice coil alignment doesn't
matter as sound below these frequencies is omni directional.
Another choice that can be made when using a subwoofer
is whether to run the mid/hi speakers full range and
add the sub woofer in addition to them or as in the
case of a Mackie SRM 450 and many other powered speakers,
engage the button that drops out the low end from being
produced by the mid/ hi frequency speakers. Obviously
if we run everything full range the low frequency capability
of the system is increased. But if the sub woofer can
give enough bass volume by itself then taking the low
end out of the mid/hi speakers leaves more headroom
for the mids and highs. This is a choice that can be
experimented with to see what works best in a given
situation. Rooms that are acoustically already bass
heavy will be better served by using the sub for bass
only and rooms that seem to lack bass may be better
served with all speakers running full frequency. Obviously
critical speaker placement and configuration is dependent
upon how loud and full a mix is desired. A band playing
loud with all instruments mixed and depending on the
PA for low end is different than a band only reinforcing
vocals on top of its stage volume.
MIXER PLACEMENT
If an engineer is going to be mixing the performance,
the mix will sound much better if the engineer can set
up the mixing position in an optimum place in the venue.
This is not always possible and some venues only allow
the mix position to be set up in a way less than optimum
position (as in behind the PA or on a balcony) potentially
causing an uncontrolled poor mix. But if the choice
is left up to the engineer then what is the optimum
place to set up? My opinion is to be in the center of
the projection of the speakers on either side of the
stage. This lets the engineer hear both speaker stacks
couple together and is the optimum sound point for frequency
response. In regards to how far back from the stage
the mix position should be, I would recommend in the
front half of the room. The further back the mixer is
placed the more prone it is to hear reflections off
the walls in addition to the sound coming from the speakers.
Also bear in mind that given the speed of sound, after
fifty five feet back from the speaker stacks the sound
is delayed. The further back you go, the more the delay.
This is why at large concerts when other sets of speakers
that are employed further back from the stage they are
time delayed to match the sound coming from the main
speakers. If they weren't you would hear the sound from
the speakers by the stage after the speakers closest
to you as if there was a delay effect on the sound.
Next time you are far away at an outdoor concert, watch
the drummer. You will see him hit the drums before you
hear the sound. This always drives me nuts.
LINE CHECK
Once all equipment is set up and working it is time
for a line check. This is where all instruments and
voices are checked individually and calibrated on their
mixer channels. The engineer will ask each musician
to play one at a time at (hopefully) the volume they
will use during the performance. The trim controls are
then adjusted on each channel to a setting a bit below
clipping ( I explained this in depth in an earlier article
in this series). The EQ on each instrument can be worked
with at this point also. Having all the gains set in
this fashion sets up the mixer to be able to process
all signals at what is called Unity Gain. By this I
mean all signals can flow through the mixer at an equal
level and one that the mixer will not distort or add
noise too. Any controls changes made on any channel
will be similar in response to changes made on any other
channel and if the faders and master faders are operated
near the "0" points or below, the mixer will
not distort. The next thing to do is to get ready to
set up a mix. All channel faders should be set to their
"0" point which is about at 2/3 of its travel.
You will see a 0 or U for unity gain on the scale to
the side of each fader. Setting the fader at the "0"
position means that as the faders are moved to create
a mix you are at a point created by design for the operation
of the fader that provides smooth and gradual change
in the signal level as opposed to erratic and uneven
changes in level. A solo or level change can be easily
executed. A mix could be set up on the faders lower
on their travel but it will be very hard to control.
The master fader should be brought up from off. It will
run clean between "0" and off so find the
appropriate volume needed. Remember sound checking in
an empty room will sound different than when a room
fills with people so according to the acoustics of different
venues you may not be getting a complete picture of
what the performance will sound like. Outboard gear
such as equalizers and compressors can also be set at
this point using the same unity gain technique. As far
as EQ on the channels and outboard EQ are concerned,
it is best to start with everything flat. Our ears hear
EQ differently at lower and higher volumes so it is
important to set the system at a level close to what
the performance will be at before any equalizing is
done. Turning on a lot of bass at a low volume and then
bringing the system up in volume will add more bass
causing muddy sound and also will tax the amps and speakers
needlessly. EQ should be looked at as a seasoning to
adjust things from their natural flat point at performance
volume. Also, it is always better with EQ to cut rather
than boost. You can create more bass by taking away
mids rather than adding bass. It's all relative and
keeps things from being overdriven.
MIX STYLE
According to the size of the venue and type of event,
what is handled by the sound system can vary greatly.
A lounge or wedding band in a smaller venue may only
need the sound system to produce vocals, all other instruments
and drums coming off the stage to the audience. In a
large venue everything on stage is reproduced by the
sound system with the stage sound having no influence
on what the audience hears. In between these two extremes
are the venues where the stage sound can be heard along
with the mix from the engineer. Here is where it can
become a problem. A loud guitar player will come screaming
off the stage and be loud in a tight beam of projection
from the guitar amp. This will make the guitar too loud
at some areas in the room and the sound man may not
even hear this from his mix position. A loud drummer's
snare in a smaller venue may be too loud for the sound
system mix even if the snare is off in the mix. A level
of cooperation and compromise must be sought for the
good of the mix. Musicians may need to limit their volume
from the stage into the audience by either turning down
or facing their speakers away from the audience. As
an alternative the sound man can use the stage volume
as the basis for the mix and fill in what is needed
with the sound system, though this never works as well
as every instrument mixed through the system.
SOUND CHECK
If time and the venue permit after the line check the
band can play a few songs to make sure the mix is right.
A good line check with a professional engineer is usually
sufficient and they will have the mix happening by the
first chorus, but a sound check can help the musicians
get a feel for the acoustics of the venue and get a
musical balance on stage that they are comfortable with.
There is nothing worse than a jumbled, out of balance
stage sound. Even if things sound good audio wise in
the house the feel and groove will not be there.
MONITORS
The last thing to discuss concerning
live sound set up are monitors. This is a subject of
incredible passion with some musicians and can cause
incredible friction between performers who have differing
viewpoints on how they should sound. I remember one
band during the eighties that was performing before
my band went on. I was sitting in the dressing room
when the stage door flew open and two band members engaged
in a fist fight came tumbling down the stairs with blood
flying everywhere. What were they fighting about- Monitors.
The band broke up the next day. Their guitar player
(not involved in the fight) was Reb Beach who after
they broke up got to join Winger.
Monitor systems can be as simple
as one monitor for the lead singer, amplifying only
his voice, to systems that provide an independent mix
for each musician with a dedicated monitor board and
engineer. If you are running a simpler system controlled
by the main mixer, place the monitors on the floor in
front of the vocal mics facing the performers to minimize
feedback. Work with each mic to maximize level and minimize
feedback bearing in mind there will also be some reinforcement
heard from the main PA. Don't frustrate yourself by
expecting more out of the monitor system than it can
produce. Remember the Beatles not only had no monitors
but they were singing while the audience was screaming.
Listen to live recordings of them and your will hear
in spite of that they were singing in tune.
Steve
Weiss is the owner and main technician of Steve Weiss
Electronics Inc. He is experienced in the repair
of analog and digital musical equipment. This includes
everything from Vintage Tube Amps and Pro Audio equipment
to Digital Keyboards There is also a guitar repair
shop staffed by some of the areas top guitar repair
techs. He is authorized for warranty work on most
major brands. Steve Weiss Electronics is located
inside of Sam Ash Music at 5460 West Sample Road
Margate, FL 33073 954-975-3390 Ext 272. Steve has
also spent 25 years on the road as a performing guitarist
and is the designer of Primal Guitar amps that can
be seen at Primal
Audio.com Steve can also be reached at stevew@metromusicmayhem.com |
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