Transcript Sound Systems

Sound Systems
The Basics and More
Basics and More
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The Cost of Safety
How Sound Travels
Cables
Microphones
Speakers
Electronic Equipment
How this relates to musicians
How this relates to GOD
Question and Answer
The Cost of Safety
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Electrical
Cables
Volume Levels
Dollars and
Sense
Rigging
Electrical Safety
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When handling high
voltage connectors,
grasp them with the
outside of the hand NOT
the inside
Do NOT unplug a
connection by pulling on
the cord
Do NOT lift earth ground
connections
Electrical Safety
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When you are
electrocuted on the
hand one of two things
could happen. Your
hand will close up if
shocked on the inside
and will open and pull
away when shocked on
the outside
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Pulling connections by
the cord could cause
electrical shock or
damage to the cord or
the equipment it is
attached to
Lifting the earth ground
removes protection for
you and the equipment
designed to use it
Cable Safety
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Putting tension on
a cord and using
tangled cords
creates hazards
Stepping on cords
damages them
and could
damage the
equipment they
are connected to
Cable Safety
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Look down when
walking on a stage
and avoid running.
Keep the cords out
of walking areas
Use extra caution
when a stage is dark
as most cords will
become almost
invisible
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Do NOT step on or
place things on
cables. They can be
damaged by such
things as hard soled
shoes, stands,
chairs or other
objects
Volume Level Safety
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The threshold of
pain is 120
decibels and can
cause temporary
hearing loss
Permanent
hearing loss
beings at 140
decibels
Volume Level Safety
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Avoid long term
exposure to high
volume levels that
lead to permanent
hearing loss.
Examples are a live
concert or playing
headphones loud
enough that your
ears wax within a
couple of minutes
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Hearing damage
caused by high
volume levels is
permanent in most
cases. If you feel
you need to cover
your ears or you are
beginning to feel
pressure then this
should tell you the
volume is too high
Dollars and Sense
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High quality does
NOT always relate
to high durability
Properly maintaining
the components of a
sound system can
extend their life
Dollars and Sense
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Some of the most
expensive
equipment is also
the most delicate
No one product is
indestructible
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High quality can
come with a high
cost of upkeep.
Ignoring that cost
can increase the risk
of failure and cost
and damage to
other equipment
Rigging
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California seismic code requires that
ALL overhead rigged lights or other
equipment MUST have safety cables
ALL stage props for productions or
otherwise MUST be fire retardant
Improper rigging is an insurance claim
waiting to happen
How Sound Travels
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Frequency verses
directionality
Frequency verses
perceived volume
level
How Sound Travels
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Frequency verses directionality
– The lower the frequency the less
directional it is
– The higher the frequency the more
directional it is
How Sound Travels
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Frequency verses perceived volume
level
– The lower the frequency the longer it takes
to fully develop
– The higher the frequency the less time it
takes to fully develop
Cables
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How they work
Care and
handling
Different types of
cables
Cables
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How they work
– They consist of strands or solid wire made
of either copper, tin, silver or gold. Then
these wires are insulated with a rubber or
plastic compound
– Cables can have many of these insulated
wires together to meet various design
needs
– Shielded cables are the same but have
stranded wire or foil that completely covers
the inner wire. This outer wire is commonly
called the ground or shield
Cables
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Care and handling
– Kinks in cables are one of the most
common causes of failure
– Connectors are the second most common
cause of failure
– Improper wrapping of cable causes tangles
and leads to cable damage
– Excessive tension or pressure where the
connector and cable come together is
another common cause of cable failure
Cables
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Different types of cables
– Microphone cables are used primarily for
connecting microphones to a sound
system. These commonly use XLR
connectors.
– Speaker cables are used to connect
speakers to a sound system. These use
speakon, 1/4 inch, banana plug or bare
wire connectors depending on the
installation
Cables
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Different types of cables (continued)
– Patch cables are used to connect sound
equipment together or are used in a patch
bay. These use 1/4”, RCA ,XLR or TRS
connectors depending on the equipment or
patch bay design
– AC cables or extension cords are used to
connect sound equipment to electrical
outlets. These should be kept away from
the other types of cables for noise reasons
and shouldn’t run parallel with audio cables
Microphones
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How they work
Care and
handling
Connecting
Positioning
Microphones
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How they work
– They are technically called a transducer.
This is because they convert one form of
energy to another. They convert sound
waves in the air into electrical sound waves
that run through wire
– They consist of a diaphragm that moves
with the sound waves in the air. This is
converted by inductance or capacitance
and then into an electrical representation of
the sound wave
Microphones
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Care and handling
– They should be stored in a dry, well
padded case
– They should not be held by the cable
unless by design
– They should not be hit or dropped
– They should not be used near water
Microphones
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Connecting
– Turn off or mute the channel you intend to
connect the microphone to. Then connect it
– Do not just pull a connector out of a
microphone without first wiggling the
connector. This is done to ensure the
internal microphone connection is not
pulled out along with the cord connector if
it were loose.
Microphones
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Positioning
– Do NOT aim a microphone directly at a
monitor or speaker
– Make certain the microphone follows your
mouth
– Angle the microphone at roughly 45
degrees from your mouth
– Keep the microphone within two to six
inches from your mouth
– Do NOT use omnidirectional mics around
monitors
Microphones
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Positioning (continued)
– Choir or overhead mics should be aimed at
the top row of singers and placed a few
feet from the first row of singers. Large
choirs or groups require more mics using
similar techniques.
– Boundary mics should be placed one or
more feet in front of the speaker on a hard
surface at waist or chest level or on a floor
depending on the application.
Microphones
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Positioning (continued)
– Lapel mics should be 2 to 3 buttons down
on a collared shirt. If the mic is
omnidirectional then dropping down to the
3d or 4th button is preferred
– Headset mics should be worn so that the
mic is aimed directly at the mouth or cheak
depending on the design
Speakers
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How they work
Care and
handling
Connecting
Positioning
Speakers
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How they work
– They are also a transducer for the same
reasons a microphone is
– They convert an electrical representation of
a sound wave into sound waves that move
air that the human ear can perceive
– They consist of single to multiple cones,
domes or diaphragms that move air to
create sound waves by either electrical
inductance or capacitance
Speakers
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Care and handling
– They should be stored in a dry place
– They should not be driven to the point
where there is audible distortion
– They should not be under or dramatically
over powered as these are the most
common causes of speaker damage
Speakers
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Connecting
– They should be connected with the proper
gauge of wire for the power they will need
to operate optimally
– Do NOT disconnect speakers while they
are playing unless the amplifier used can
tolerate this
– Do NOT connect more than two speakers
in parallel to one amplifier unless it is rated
to support it
Speakers
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Connecting (continued)
– Most average to high quality speakers
used for sound systems are rated for at
least 200 watts. It is not uncommon to see
600 or 1200 watt ratings. Even if you can
connect or disconnect a speaker when
powered to full output. A word of warning.
I know of a technician that used a high
quality 300 watt amplifier for light arch
welding
Speakers
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Positioning
– The main speakers should be mounted
between the stage and audience and
directed at the audience
– Most speakers are designed to work
optimally in the upright position with few
exceptions
– Whenever possible ALL microphones
should be behind the main speakers
– When positioning monitors consider the
polar pattern of the mic you are using
Speakers
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Positioning (continued)
– Monitors should be pointed up at the
performers
– Avoid excessive monitors to control
feedback and stage volume
– Do NOT place monitors side by side or
within roughly six feet of each other
– Subwoofers should NOT be in close
proximity to mics
– Subwoofers should NOT be given
microphone signals
Electronics
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How they work
Care and
maintenance
Powering a sound
system
Using a Cassette
Deck
Using a CD Player
Using a Direct Box
Using a Mixer
Electronics
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How they work
– Most analog electronic equipment in a
sound system consists of multiple
amplifiers. These slowly increase the
levels from a small signal that would come
from a guitar or microphone to a level
sufficient to power a speaker
Electronics
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Care and maintenance
– Equipment should be kept in a dry place
away from water and dust
– Equipment should be kept away from high
power wires and motors that are commonly
found in refrigerators, air conditioners and
other similar devices to minimize noise and
other forms of electrical interference
– All equipment should be grounded properly
to prevent fire and electrical shock hazards
Electronics
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Powering a sound
system on in order
– Cassette decks,
CD players,
equalizers and
other similar
equipment
– The Mixer
– The Amplifiers
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Powering a sound
system off in order
– The Amplifiers
– The Mixer
– Cassette decks,
CD players,
equalizers and
other similar
equipment
Electronics
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Powering a sound system (continued)
– Devices with moving parts like CD players
or Cassette decks could react poorly to
high humidity or cold weather. In these
cases leave the equipment on roughly half
an hour before using
Electronics
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Using a Cassette Deck
– If the tape is not wound tightly on the reels
then use a pencil or other device to remove
the slack. Some lower quality decks will
eat a tape for this reason alone
– If the deck does not have auto bias
selection make sure to pick the right setting
– Do not use metal tapes on decks that are
not designed for them. This will wear out
the tape head pre-maturely
Electronics
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Using a Cassette Deck (continued)
– To cue a tape rewind the tape to the point
where the track will start. Play the tape
and listen for the song to begin. As soon
as the music starts press Stop on the deck.
Remove the tape and use a pencil or other
device to turn back the reel approximately
one and a half turns
Electronics
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Using a CD Player
– When cleaning CD’s use a soft dry cloth
and move from the inside to the outside
– Keep CD’s away from direct sunlight, high
humidity or excessive heat
– Do NOT write on the top of a CD unless
you know the pen you are using has no
alcohol in the ink
– Do Not place labels off center on the CD as
some players will not play the disc due to
wobble
Electronics
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Using a CD player (continued)
– Cueing a CD is as easy as inserting the
disc and selecting the track and pressing
play. Older players take longer to start up
so selecting the track and then pausing the
player may help make up for this delay
Electronics
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Using a Direct Box
– A Direct Box is also known as an
Impedance matching transformer
– This device should be used when
connecting unbalanced, high impedance
devices to a sound system, such as VCR’s,
TV’s, computers, electric guitars,
keyboards and other similar devices
– Active versions require a battery or can run
from phantom power
– Lifting the ground should be used only as a
temporary solution
Electronics
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Using a Direct Box (continued)
– This device may not be needed if the cable
run is under 25 feet and there is a high
impedance input on the sound system
– These devices come in passive and active
versions. The active version is more
versatile and is better at isolating noise
– They are connected to the sound system
with a microphone cable and connected to
a microphone input in most cases
Electronics
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How to use a Mixer
– This is the most versatile and thus can
easily be considered the most confusing
part of the sound system
– Try not to look at the whole board but look
at the area you need too and focus in from
their. Much like reading a map you first get
the cross streets and then the address
Electronics
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How to use a Mixer (continued)
The controls in each channel:
– Trim: This is the first volume control for the
channel. It has a very broad range of level
to cover most every option
– Line/Mic: This is a switch to select between
the line or mic input. This way you can
have multiple devices on one channel and
pick which one you want to use
Electronics
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How to use a Mixer (continued)
– Phantom Power: This is a switch to provide
49 volts of power for mics or direct boxes
that require it
– High Frequency Control: This is much like
the treble tone control on your home
stereo. It adjusts the amount of gain or cut
in the high frequencies
– Mid Frequency Selection: This control
allows you to pick the frequency you will
boost or cut in the mid frequency range
Electronics
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How to use a Mixer (continued)
– Mid Frequency Control: This is much like
the Midrange tone control on your home
stereo. It adjusts the amount of gain or cut
in the midrange frequencies
– Low Frequency Control: This is much like
the Bass tone control on your home stereo.
It adjusts the amount of gain or cut in the
bass or low frequencies
– Aux Sends: These allow you to direct
signal from one channel to one of the
Auxiliary buses
Electronics
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How to use a Mixer (continued)
– Sub Group assignments: This allows more
control over where the signal from the
channel will go
– Pan Control: This is much like the balance
control on your home stereo. You can
select where the signal will go
– Mute: This does exactly what it sounds
like. It mutes the signal coming out of the
channel
Electronics
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How to use a Mixer (continued)
– PFL: This stands for Pre-Fader Level.
Use this to monitor the signal on the
channel and to set the channels gain
structure
– Fader Control: This is the most obvious
control and once your gain structure is
setup you can use the fader to control the
output level of the channel
– Presence Meter: This is a small light that
indicates a signal is present and a peak
light for when the channel is clipping
Electronics
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Gain structure: This
is critical for good
mixing. Use the
PFL and bring the
Trim level up until
the signal is
averaging 0 decibels
Bus: This term
refers to the path a
group of signals
travel on
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Clipping: This is
when the signal has
gotten to a level
where distortion is
being created in the
original signal
Decibels: This is the
term used to
indicate what a
signal level is. It is
also called dB.
Electronics
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Mixing Techniques (continued):
– Setting the Fader:
• Not too fast or you may get the unexpected
• Try to keep the fader around 2/3 to 3/4 of the
way up so you have some room if you need it
– Riding the Fader:
• If you must pull someone up/down then wait for
a quite or down/up tone to make your move
Electronics
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Mixing Techniques:
– Some basic tips on EQ
•
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31 Hz is Woofy
63 Hz is Boomy
125 Hz is Punch
250 Hz is Chesty
500 Hz is Honky
1K Hz is Nasally
2K Hz is Quacky
4K Hz is Tinny
8K Hz is Spitty
16K Hz is Airy
Electronics
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How it all comes together
– Sound is picked up by the microphone and
is converted to an electrical signal
– The signal is carried down a microphone
wire to the sound system
– Then the signal is passed through a mixer
where several signals are combined to
produce a signal with all or some of the
other signals combined. This is why the
mixer is the most powerful part of the
system
Electronics
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How it all comes together (continued)
– Then the signal from the mixer is sent to
various other equipment such as cassette
decks for recording and to the amplifiers
– This sound that was sent to the amplifiers
is amplified enough to power the main
speakers or the monitors
Electronics
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How it all comes together (continued)
– As you can see there is a potential for a
loop to be created here. This looping is
referred to as feedback. Feedback occurs
when a signal the sound system has just
amplified from a microphone is picked up
by the same or other microphone in the
system again. Thus, the system attempts
to amplify this again-and again-and again
How this relates to musicians
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How to use
monitors
effectively
How to use
microphones
effectively
How this relates to musicians
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How to use monitors effectively
– If singing in a group and you are all using
one monitor then try practicing with all of
your monitor levels at the same setting
– If singing with an amplified instrument that
is not run through the sound system try not
to get in the habit of turning your level up
when something else does
– If possible stay in line of site with your
fellow players. Communicate constantly
How this relates to musicians
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How to use microphones effectively
– If you want a fuller sound get closer to the
microphone. However, do NOT “eat” it
unless you really want that effect
– If your range in volume changes then try
changing the distance of the microphone in
relation to your volume. You do not want to
get more than six to eight inches away or
you will probably start to sound very
hollow, tinny or distant
How this relates to musicians
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How to use microphones more
effectively (continued)
– If you sing in a choir or large group and
have a microphone placed above you. Try
not to sing with your head tilted upward.
This causes a strained effect in your voice
and could cause your voice to be over
emphasized
How this relates to GOD
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Purpose of the
Sound System
Purpose of the
Musicians
How worshiping
together achieves
a common goal
How this relates to GOD
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The purpose of the Sound System
– The sound system is there to amplify and
assist in creating a spirit of worship in the
church
– The sound system operator is NOT a
position of power
How this relates to GOD
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The purpose of the Musicians
– The musicians and singers are there to
worship GOD and thus assist in creating a
spirit of worship in the church
– Nobody is there to play solo. They are
there to worship together as a single voice
with everything and everyone in their place
How this relates to GOD
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How worshiping together achieves a
common goal
– The spirit has more freedom to move and
work through us as HIS instruments
– We are all brothers and sisters in Christ
and Christ must come first in ALL things
and ALL things must be done for HIS glory.
Reference material
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Web site
– www.churchsoundcheck.com for discusion
groups, links to manufacturers and more
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Books
– Sound Reinforcement Handbook, 2nd
Edition by Gary Davis and Ralph Jones
– Guide to Sound Systems for Worship by
Jon F. Eiche
Sound System Basics
Question and Answer
Hands on Training