Understanding Understanding BasicBasic Signal Signal

FlowFlowLets get connected!Lets get connected!

Input SourcesInput Sources• Microphone level approximately -60 dBu

• Line level approximately +4 dBu

• -10 dBV Standard voltage reference level for

consumer and some pro audio use (Tip: RCA

(or phono) connectors are a good indicator of

units operating at -10 dBV levels.)

The point is, anywhere in this chain, if the wrong connector is used, or a level setting is wrong, the loss of gain cannot be made up somewhere in the chain without a addition of noise

When you think of the sound for any given instrument or device. Think of the sound/signal flowing like streams, lakes, etc.

Balanced & Balanced & unbalanced linesunbalanced lines

Balanced LinesBalanced Lines• Two conductors are driven equally and oppositely with respect

to ground. (3 conductors = positive, negative, ground)

• Balances lines are the preferred method (for hum free) interconnecting of sound systems using a shielded twisted pair wire. The principal behind balanced lines is that the signal is transmitted over one wire and received back on another wire. The shield does not carry any information, so it is free to function as a true shield for the plus and negative wire.

Balanced LinesBalanced Lines• Mic cables are balanced lines. They use a gendered (male

and female) XLR connector

• XLR® is a registered trademark of ITT-Cannon - a manufacturer of connectors. The original model number series for Cannon's 3-pin circular connectors - invented by them - now an industry generic term. (you will still hear old rock n’ roll sound dogs say…”go plug that into the cannon jack”

• Balances lines are the preferred method (for hum free) interconnecting of sound systems using a shielded twisted pair wire. The principal behind balanced lines is that the signal is transmitted over one wire and received back on another wire. The shield does not carry any information, so it is free to function as a true shield for the plus and negative wire.

• Because there is three conductors, there must be three points on the connector to carry the current.

RCA = unbalanced

TS = 1/4” Tip Sleeve = unbalanced

TRS = 1/4” Tip Ring Sleeve = balanced

XLR female panel mount = balanced

XLR female cable = balanced

RCA JackRCA Jack

• RCA jack (AKA phono jack) The Radio

Corporation of America (RCA) originally

developed this type of pin connector for internal

chassis connections in radios and televisions

during the '30s. It was adopted at this same time

for phonograph players - hence the reference

phono jack. Now the standard for use in line

level consumer audio and project studio sound

equipment, and most recently to interconnect

composite video signals.

TS (tip sleeve) 1/4” PlugTS (tip sleeve) 1/4” Plug

• The TS (Tip Sleeve) or 1/4” or Phone Plug was originally invented for the telephone industry… picture a Erin Walton working as a telephone operator using the telephone patchbay “connecting” John Boy to the Drew Drop Inn.

• This is not the recommended plug for high power-speaker connection. This is due to its limited power capabilities.

TRS (tip ring sleeve) TRS (tip ring sleeve) 1/4” Plug1/4” Plug

• Balances lines can also use a 1/4” type of connector. This is called a Tip/Ring/Sleeve or TRS

• This is not a “guitar cable”• This is not wired the same as a stereo

headphone jack.• Balanced lines are used to interconnect

system equalizers, crossovers and other balanced equipment.

• There is no electrical difference between XLR and TRS but we prefer the locking properties of the XLR.

TRS maleTRS male

XLR femaleXLR female

Unbalanced LinesUnbalanced Lines• 2 conductors - center positive conductor is

surrounded by a shield• An unbalanced line transmits the audio signal

between one wire and ground. The circuit path is down the wire and back through the shield cable connected to ground. Ground is the return path; the circuit does not work without it.

Passive Direct BoxPassive Direct Box• This is used to connect keyboards and other

electronics that have a line/Instrument level out (typically a 1/4” unbalanced out) to low impedance mic level out

• As a passive unit, the signal is as good as the transformer that is built within it.

• Get one with a ground lift switch.

• Generally, by going through a passive DI, (direct injection) you loss from 3 to 6dB of signal.

Passive Direct BoxPassive Direct Box• 1/4 unbalanced

in to XLR balanced out - This is how to connect to your board

• Great for keyboards & guitar preamps.

Active Direct BoxActive Direct Box• This is used to connect bass guitars and

other electronics that have a line/Instrument level out (typically a 1/4” unbalanced out) to low impedance mic level out

• Higher input impedance will help preserve upper harmonics

• Better transformer - more highs - more lows

• Get one with a ground lift switch.

• No loss but needs a 9 volt battery or phantom power.

• Do not plug your electric guitar into a “normal” direct box

• Its sounds brittle, crunchy…well…just bad.

SpecializedSpecialized Direct BoxesDirect Boxes

• There is an alteration of the sound caused by the frequency response of the guitar amp speaker and a microphone in front of that speaker.

• Specialized Direct Boxes (D.I.’s) are manufactured to reproduce this sound

What is it What is it and why do and why do

I need it?I need it?

Phantom PowerPhantom Power ! !

• Phantom power is a system of providing electrical power for condenser microphones (and some electronic pickup devices) from the sound mixer. The system is called phantom because the power is carried on standard microphone audio wiring in a way that is "invisible" to ordinary dynamic microphones.

• Must use a balanced cable to deliver it to the stage

Lets look at some Lets look at some typical inputs to the typical inputs to the

consoleconsole

Mic Note a “hot” mic is not necessarilyindicative of a superior mic

CassetteLine Level

VCRLine Levelwith 1 : 1Transformer

Wireless ReceiverMic or Line level out

Direct Boxunbalanced to balanced

NormalizinNormalizingg• In audio terms, normal or normalize is a zero state.

This means:

• Trim - off

• Aux - off

• Eq - zero

• Hi Pass filter - zero

• Pan - center

• Assign - none

• Fader down

Lets look at a Lets look at a typical typical

channel stripchannel strip

•Here is a closer look at the

Trim Control

TRIMTRIM ControlControl• Signals connected to the

channel inputs could vary

from extremely small to very

large. TRIM sets the gain (volume level) of the channel input amplifier.

Proper setting of the TRIM control is essential for good noise and headroom performance.

The Mic PreampThe Mic Preamp• This amplifier brings the very low signal level of a

microphone (approximately -60dBu) up to line level (approximately 0dBu). Mic preamps often have their own volume control, called a trim control, to properly set the gain for a particular source. Setting the mic preamp gain correctly with the trim control is an essential step in establishing good noise and headroom for your mix.

• Lets assume that the console is a “normalized” state • Engage the PFL button (Pre Fader Listen) which will

put this channel to the LED display• With the fader down, you will see and not hear the

input signal if your console has a metering section• Remember that after you adjust the EQ for this

channel, you might have to re-adjust the TRIM. (if you add lows to the EQ…you have also added signal so you will have to adjust the TRIM down.

TRIMTRIM Control SetupControl Setup

• Mic Level input A mic level signal (usually but not always coming from a microphone) is generally below -60dBu.

Here is a closer look at typical channels input connectors

• Balanced or unbalanced line inputs are used for line level inputs

• line levelA signal whose level falls between -10dBu and +30dBu.

• Note - a balanced line level input can use an XLR jack - but it is not a mic level input

• This allow us to “insert” a modifying device (such as a compressor, FX unit, EQ etc) into this channel.

• Insert points are typically after the Trim control but before the channels EQ, fader and Mute.

• Inserts can also be found on Group Masters and Main outputs

Lets look at a Lets look at a typical typical

unbalanced unbalanced insert cableinsert cable

• TRS is inserted into the channel, group master etc• Tip is out of the sending console• Ring is return of the sending device• Sleeve is the common ground to complete the

unbalanced circuit

TRS

TIP to device input

RING to device output

Unity GainUnity Gain• VERY IMPORTANT: Unity gain is the point at

which no level is added to or subtracted from the nominal signal.

• If after setting the trim, you add 6 dB of lows…you will then have to readjust (tweak) the trim to compensate.

• Proper setting of the input level and output levels of all devices (FX units, compressors EQ etc) is important to the signal to noise ratio.

EQ, compressor, and crossover all have gain stages before it goes down a 100+ foot snake before it gets into the amplifier (the final gain stage)

The point is, anywhere in this chain, if the wrong connector is used, or misuse of unity level setting, the loss of gain cannot be made up somewhere in the chain without a addition of noise

• The function of the amplifier is to amplify the audio signal that comes upstream from this device.

• If part of that audio signal contains noise, that noise will also be amplified.

• A power amplifier level/volume/gain” controls are input sensitivity controls. (no matter how they are calibrated.) They are not power controls. They have absolutely nothing to do with output power. They are sensitivity controls, i.e., these controls determine exactly what input level will cause the amplifier to produce full power. Or, if you prefer, they determine just how sensitive the amplifier is. For example, they might be set such that an input level of +4 dBu causes full power, or such that an input level of +20 dBu causes full power, or whatever-input-level-your-system-may-require, causes full power.

• They do not change the available output power. They only change the required input level to produce full

output power.

• Soooo…you do not need your power amplifier level/volume/gain turned up all the way. Properly adjusted…you will also find your idle noise will disappears!

How do I set my amplifiers?How do I set my amplifiers?

• Play a source material indicative of the type of music program you use. (remember if playing a CD, there is no stage volume - factor this in to your level setting)

• Set unity at the console and throughout the signal chain.

• Start with the amplifier or amplifiers off.• Slowly bring them up to the volume you need in

this room. (then add a scooch)• Your signal to noise ratio will be incredible!

Connecting the amp to Connecting the amp to speakers (portable)speakers (portable)

• Neutrik NLFC is the recommended connector for speaker connection.

• High Current

• Locking

• No exposed connectors - no possibility of shorting

• This series of professional speaker and amplifier connectors is recognized as the industry standard. The Speakon® product line now comes in 2,4, and 8 contact versions.

• This connection system offers the "quick lock" locking system and inserts on it's cable ends. The inserts feature solderless connections using screw type terminals with a captivated pressure plate. No special tools are required making these connectors 100% field repairable.

Connecting the amp to Connecting the amp to speakers (permanent)speakers (permanent)

• The required size (or gauge) of the conductors depends on three factors:

(1) the load impedance of the speaker

(2) the length of cable required

(3) the amount of power loss that can be tolerated.

• Keep speaker wire length to a minimum. (In large installs…where there is a large central cluster of speakers, the amp racks are mounted above the speakers - The amps are then remote configured, controlled and monitored via a computer application at the F.O.H. such as Crown IQ for Windows)

• 12 gauge conductor size is typical - the outer jacket is not indicative of the size of conductor

• Here is a closer look at the

AUX Send section

AUX SENDSAUX SENDS• This allows the operator to tap off

the channel signal to an aux send bus. This aux send bus then can be routed auxiliary devices.

• Aux sends are generally used to provide mixes for stage monitors, effects units, and recording devices.

• Aux send settings do not directly affect the signal routed to the main and submix buses.

……to pre or not to pre…to pre or not to pre…...that is the question......that is the question...

• There are two types of basic aux sends...Pre EQ/Pre Fader and Post EQ/Post Fader

• Consoles will have a combination of these choices

Pre Fader/Pre EQ Aux SendPre Fader/Pre EQ Aux Send

• Pre EQ means the aux send is tapped before (Pre) the channel strip EQ. You can change the EQ on the channel and it will not effect the tone of this send.

• Pre Fader indicates the aux send is tapped before that channels fader. You can raise or lower the fader and it will not effect the volume of the this send

• Pre Fader/pre EQ aux sends are usually used to feed stage monitors. This helps provide a stable tone and volume environment to the stage performer

QuestionQuestion• The band is cooking along on a real

aggressive song. Everything is sounding great…and here comes the guitar solo.

• When you bring up the guitar channel fader, the whole band has their hair parted back.

What just What just happened?happened?

QuestionQuestion

The guitar channel fader was wrongly set to Post Fader/post EQ and not to the correct Pre

Fader/Pre EQ.

Post Fader/Post EQ Post Fader/Post EQ

Aux SendAux Send• Post EQ means the aux send is tapped after (Post)

the channel strip EQ. You can change the EQ on the channel and it will effect the tone of this send.

• Post Fader indicates the aux send is tapped after that channels fader. You can raise or lower the fader and it will effect the volume of the this send

• Post Fader/Post EQ aux sends are usually used for effects or recording sends.

QuestionQuestion• You have a performer singing to a cassette

track. This track is going to the Mains (for the audience) as well as monitors (for the performer). This particular track has a 37 second fade out but you must fade it out 7 seconds.

Do you choose Pre or Post fade?Do you choose Pre or Post fade?

Is that your final answer?

• Here is a closer look at the EQ

control

• The channel EQ is designed modify (if needed) augment or remove the frequency response of that channel’s input.

• Low…Mid...Hi…fixed center…sweep…parametric…shelf…hi-pass…are types of EQ.

• Low cut can be fixed or adjustable

• Here is a closer look at the

ASSIGN section

• You should not force or push system beyond the parameters of your system such as amplifier power, speaker frequency response and room acoustics.

• If you have a system that cannot reproduce 25hz (really low - bass), adding at the EQ will only injure your system.

• Keep in your mind ...the mix• do I really need to add that much low end

to the keyboards…it will only mask & muddy the electric bass

• If I have the Highs on all the channels up…there is not a difference in the sound palette.

• You can mix with EQ to make things heard, not just volume!

• This sections routes the source to the Group/Buss or Main Mix faders.

• By adjusting the PAN control, source material can be directed to where you want

What's a bus (or group) What's a bus (or group) and why do I want to get and why do I want to get

on it?on it?

• 8 Buss master section

• Lets add 8 channels for drums

#1 Kick#2 Snare#3 Hi-Hat#4 Tom 1

#5 Tom 2#6 Floor Tom#7 OH#8 OH

Now lets assign all the drums to group master #1

• After setting the individuals faders, you now can control this group of assigned faders at the group master fader #1.

• You can also insert compressor and gates on the kick, snare, etc individual channel.

• Then you can also insert a compressor on the group master 7 that is keyed by the lead vocal.

• Lets add 6 channels for worship team

#9 Nic#10 Chris#11 Pete

#12 Mary #13 Sylvia#14 Laura

Lets assign the worship team to group master #7

• After setting the individuals faders, you now can control this group of assigned faders at the group master fader #7.• Then you can also insert a compressor on the group master that is keyed by the lead vocal.

Drums/bass Keys Guitars Brass Strings Choir Team Lead Vocal

Here is one example of group master assignments

Lets talk about Ducking (or side chaining)

• You can insert 8 compressor into each group channel insert.

• These can controlled by the lead vocal by “telling” compressor 1-7 to “look” for the “key”…compressor 8 - the lead vocal.

• When the lead vocal sings…it sends a signal to compressor 1-7 telling them to take the volume down of each of the sidechained compressor ‘automatically”

• Properly set, this technique insures a great mix especially when you are mixing many channels.

• Enrique sings background on some songs and other songs lead. By reassigning his individual channels pan control from hard left (group master 7 background vocals) and panning it hard right (group master 8 lead vocal) and doing the opposite to Sams individual channel, who now be singing background, the compressor key priority is easily changed.

• Pastors wireless lav or podium mic can have an individual channel inserted EQ and compressor.

• These can be assigned directly to the Main Mix output.

• You can easily mute group masters 1-8 when the pastor is talking.

• Source material such as VCR audio, cassette and CD can also be routed directly to the Main Mix output