State Tech Training Spring 2014

Welcome to State-Aud-Con

“State Tech Audio Concepts”

State Tech Plaza

Faces to know – Pro Staff

Mark Venhuizen

Jen Lichty

Angie Courteau

Faces to know – more Pro Staff

Jenn Novotny

Keith Skogstad

Lindsie Bartley

Coordinators Kate VanHeel

Nathan Rausch

Sidney Smith

Brian Eiesland

Rigs

• Sound C (with or without subs)• Extremes• EAW• JBL• DJ Rig• House Sound (VBR, Campanile, Wills, Einstein)

Types of events• Speeches• Panel Discussions • PowerPoint presentations• Stage Load-ins• International Nights• Banquets• Dances• Bands/Concerts

State Tech Acronyms & TermsMost common

• FOH – Front of House• VBR – Volstorff

Ballroom• Media – Equipment rack

with media gear• FX – Equipment rack

with effects processors• EQ – Equalizer • Comp/Gate –

compressor/gate combo unit

• Mic – microphone

• EAW – Eastern Acoustic Works…our monitor and FOH gear

• Sound C – small/medium format sound system

• Extreme – very small format sound system

• DI – direct input (unbalanced signal to balanced signal)

• PCDI – personal computer direct input

Locations to Know

• VBR - Volstorff Ballroom • Camp Hope – VBR Booth• 135 Hallway/ North Hallway• Loading Dock/Freight Elevator• Data Closet • 150 Office Suite• Tech Plaza• 001 • Market Stage• Campanile/ Hobo Day Gallery

• Lewis and Clark• Jacks Place• Sylvan Green• Frost Arena • Animal Science Arena• Coughlin Alumni Stadium• PAC - Performing Arts Center• Peterson Recital Hall(Lincoln)• The Barn VS DePuy• Storage Unit

Basic components of Sound Reinforcement

• Sources – Microphones, iPods, Guitar(DI), Etc.• Mixer (Sound Board) – Analog, Digital• Signal Processor – EQ, Delay, Compression, Limiting• Amplifier• Loudspeakers – Active/Passive• Acoustical Environment – Noise/Reflections• Audience – Sufficient sound level (easy) and clarity (hard).

General Setup Goals(1) Place loudspeakers for even coverage--Aim for back row--Minimized coverage overlap(2) Use Appropriate Interconnect practices--Use Balanced Cables when possible--Correct Gauge Cable for Loud Speakers--Use DI’s for Long distance runs (6’+)(3) Establish System Gain Structure-- Set Mixer at 0dB or “Unity”--Set Amplifiers to Desired Volume.

General Setup Goals Cont.(4) Verify setup with iPod or CD Tracks--Music AND SPEECH-- Walk the audience areas and LISTEN--This is your goal for the performance.(5) Connect mics and set levels--Fader at “zero” or “unity”--adjust gain to “unity”--Watch for overload

A Quick note of “unity”

• Unity is in most cases is “Zero” however “Zero” means a variety of things in different cases. Most often it is 0dB. dB is only a reference. dB SPL, dBu, dBFS actually mean something. However, 0dB SPL is inaudible, 0dBu is generally mix position, and 0dbFS is just under clipping the system.

General Setup Goals Cont.(6) Set monitor levels--Must be at least 10db below mains in house (half loudness)--Set house first, leave house up, then set monitors

(7) Details = Ear Candy--If it does not sound good by now go back to step 1--EQ Main loud speakers--Channel EQ, Compression, Effects--Address micing problems with placement/swapping--Refine by subtraction – Simplify!

Back to dB

What is dB? A Reference!Relative: Turn it up 3dB.Absolute: Set it for 80 db SPL.Even better: Set it for 80db SPL A weighted Slow

Relative Levels The Decibel

Perceived Change dB Change Power Ratio

No change 0 dB 1x Perception Threshold 1 dB 1.26x Minimum practical change 3 dB 2.0x Goal for system changes 6 dB 4x Twice loudness 10 dB 10x 20 db 20 dB 100x 30 dB 30 dB 1000x

40 dB 40 dB 10,000x

What you need always depends on what you start with!

Absolute SPL

• Sound level change of 1 or 2 dB is barely noticeable• Ears need 10 dB SPL to perceive sound as twice as

loud• 100 watt amp sounds twice as loud as 10 watt amp

using same speakers & same distance• Switching from 100 watt amp to 200 watt amp = 3

dB increase• 1000 watt amp doubles perceived volume from 100

watt amp

Absolute Sound Pressure Levels(From OSHA, SPL A-weighted slow)

Absolute Sound Pressure Levels(From OSHA, SPL A-weighted slow)

Absolute Sound Pressure Levels(From OSHA, SPL A-weighted slow)

Other SPL Factors

• For a given power to a loudspeaker, perceived loudness depends on:–1) Distance between listener &

loudspeaker–2) Audio frequency–3) Room acoustics–4) How well listener’s ears work–5) Loudspeaker efficiency

Audio Frequencies - Hearing• Human hearing ranges from about 20 Hz to 20,000 Hz• Speech range from about 100 Hz to 4 kHz• Music fundamentals fall between 40 Hz & 15 kHz

Audio Frequencies - Harmonics• Audio waveforms contain harmonics or overtones

Audio Frequencies

Articulation

• Octave - interval between 2 frequencies having 2:1 ratio• Each doubling of fundamental is an octave • Audio frequencies cover 10 octaves• Center for articulation located in the 2kHz Octave

State Tech FOH Sound System Overview

InterconnectsUnbalancedPros: CheapGood fidelityCons: Sensitive to any input voltageNo noise immunityPrerequisites:Short cables (<1m)

¼” TS Connector

RCA (Phono) Plug

InterconnectsBalancedPros:

Good FidelityNoise immunityPolarity easily reversed

Cons:Polarity easily reversedMore Expensive than Unbalanced

XLR Connector

¼” TRS Connector

XLR Balanced

TRS ¼”Balanced In or OutUnbalanced StereoUnbalanced Insert

TS ¼” Unbalanced

RCA Unbalanced

3.5mm1/8”

Consumer –Unbalanced Stereo

Speakon Loudspeaker I/O

Banana Loudspeaker I/O

Sound System

Interconnects

BNCAntenna

Aux LightingVideo

PowerCon Aux Power

VGA Standard and High Definition Video

RS-232 Data

DVI Common on Mac video outputs

Mini DVICommon on Mac

video outputs (Most current)

Mini DisplayPort

Common on Mac video outputs (1st gen

MacBook)

HDMI High Definition Digital Video

Other

Interconnects

The Channel Strip

The Channel Strip - Signal Flow

Mid

1. Close Micing2. Beta 58 or SM 583. Avoid Boosting Filters4. Watch Monitor Levels for Feedback

HIGH

1. Long Gooseneck2. Avoid Boosting Filters3. Low monitor levels

VERY HIGH

1. 3 to 1 rule2. Vocal Support Only3. SM 81 w/ Bass Cut4. No Monitor Feed

LOW

1. Extremely close mic placement2. Electrical Feed if bass3. Reduce Stage Level4. Minimal Monitor Feed

LOW

1. Extremely close mic placement.2. Aim at center of head if thin3. Aim at rim if too boomy4. Watch levels of overhead mics.

NONE

1 Direct box.2. Near Max Output Level (90%)3. Watch for ground loops4. Good for setting starting level

Microphone Placement Tips

Mike’s Micing Techniques• For many applications, keep the microphone

as close to the source as possible

-Make sure customer speaks into the microphone with sufficient volume AND clarity, and at a very small distance from the microphone

MikeHi, I’m Mike!!!

Mic

Mike’s Micing Techniques (cont.)

• For guitar and bass cabs, place the mic slightly off-center of the cone and as close to the grill as possible without touching the grill.

Mike’s Miking Techniques (cont.)

Mike’s Miking Techniques (cont.)

1. SensitivityThe signal level post gain should be sufficient to produce a “meter zero” indication on the main or solo meter.

The factors that affect this are:1. Mic sensitivity2. Source level3. Mic-to-source distance4. Gain/Trim setting

2. PatternPolar patterns can be used to reject unwanted sound

Microphone Specs

Microphone Specs (cont)

Close-micing produces improved signal-to-noise ratio and direct to reflected ratio

4. Iteration The 3 to 1 rule Only one mic should be used for each program source (generally). Large sources may require multiple mics.

5. Polarity

3. Distance

Microphone Types

DynamicGeneral Features

-Passive (No External power)-Ultra Reliable-Low sensitivity-Robust construction-High SPL

• Tech Microphones include Beta 58, SM 58, SM57, Beta 52, Beta 56, ATM 25

Microphone Types

CondenserGeneral Features

-Active (Requires power source AKA phantom power)

-Wide Bandwidth-High Sensitivity-On-board filters (sometimes)

• Tech Microphones include SM81, Beta 87, Beta 98, Podium Mics

Phase Cancellation• Happens when a single source is 180degress

out of phase. (can happen with only 1 mic!)

Microphone Notes-Use dynamic mics when possible (more reliable, less loading on mixer, no pops)-Mic proximity affects the sound. The closer the better!-Avoid lapel microphones when possible…AT ALL COSTS!!!-Compared to lapel mics, head worn mics sound better, provide more gain, and

have less interaction with other mics and reflective sources.-Use wired mics instead of wireless when possiblePhantom PowerPhantom power is a DC power source, that is originated at the mixer, and feeds

the microphone through a standard mic cable (XLR). -Current limited by mixer design-Causes “pops” if interrupted-Requires shield connection in cable-48VDC is “standard” but other voltages can work-Turn off if not needed-DON’T supply to tape decks, ribbon mics, etc.-Turn off prior to patching mics-Needed for active DI’s, unless DI is supplied with a battery

Mixer Gain Structure

1. During the sound check, adjust each channel trim to produce a “zero” reading on the main meter.

This is the minimal level that will be needed from a single channel.

Always

-Do this before you set stage monitor levels.

-Don’t readjust trims if you are running the monitors

• For a Quick Setup, Set all the faders to “Unity” and do a quick mix with the channel trims.

Inserts• Line level signal processors can be “inserted” into the

signal chain for individual mixer channels if needed

Insert Processors: Notch Filters, Equalizers, Compressors, Effects 1. Set external device to unity2. Keep Cables Short3. Use Sparingly

Dynamic Range Control

Our Compressors

To make a compressor a limiter simply set the ratio to infinity to 1. General Rule;If you can hear the limiter, you’re using too much.If you can’t hear the compression, you’re using too little.

• Graphic Equalizer. A multi-band variable equalizer using slide controls as the amplitude adjustable elements. Named for the positions of the sliders "graphing" the resulting frequency response of the equalizer. Only found on active designs. Both center frequency and bandwidth are fixed for each band.

Graphic Equalizers

Equalizer effects

Multiple Filters

Acoustic Feedback ControlSound Systems “howl” or “screech” when the loudspeaker’s acoustical output exceeds the level of the signal at the input that produced the output signal. Basically, the system is amplifying itself.

When feedback occurs…

1. Turn it down!2. Find the offending mic.3. Move it closer to the source.4. Increase the source level.5. Move or reposition the mic.6. Reduce the number of open mics,

and/or use gates.7. Insert a notch filter on the channel.8. Redesign the loudspeaker system.

Things to avoid:-Panicking!-Using graphic equalizers as feedback filters-Feedback filters in the main signal chain.

Other Tips:-Turn down monitors or move them-Use contact pickups when possible

Active/Passive Crossovers

Active 2-Way Crossover

Active 3-Way Crossover

Crossover frequency Response

EAW SM129z

1” Tweeter12” Low Woofer

Passive 2 – Way System

EAW SM159z

1” Tweeter15” Low Woofer

Passive 2 – Way System

JBL SR Series

2” Horn Loaded Tweeter6” Horn Loaded Midrange Woofer2 – 12” Lowrange Woofers2 – 15” Subwoofers

EAW KF650z

Active 3-Way System

2” Tweeter10” Horn Loaded Mid15” Horn Loaded Woofer

EAW SB528zR

2 X 18” Woofer

Vented Enclosure

Most Common Configuration – KF650z4-Way System

EAW KF650z Splay

Questions?

Caleb will answer all of them!