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FOH Mixing Consoles,Microphone Selection, Racks,
and Wiring
D. G. MeyerSchool of Electrical & Computer
Engineering
Outline – Mixing Consoles• FOH Console Criteria• Representative FOH Console• Sample Analog Consoles• Sample Digital Consoles• Choosing Analog or Digital
FOH Console Criteria• Inputs (number/type/phantom power)• Channel inserts• Number of mix buses and groups • Number of masters (L/C/R)• Number of aux sends/aux returns• Number of aux sends/aux returns• Meter bridge• Channel input gain/attenuation• Channel EQ (parametric/shelving)• Monitoring (PFL/AFL)• Matrix output mixer• Automation (programmable scenes)
Representative FOH Console
Yamaha IM8
Typical Channel Strip
Typical Channel Strip
Signal Flow Diagram
Group/Aux Bus
Master Section
Matrix Section
Control Section
Sample Consoles• Allen&Heath• Mackie• Midas• Soundcraft• Yamaha• Yamaha
Choosing Analog or Digital• Analog consoles
– generally more “intuitive”– generally less expensive– limited “scene setting” capability– With VCA, increased automation capability– With VCA, increased automation capability– physically large for large number of channels
• Digital consoles– generally less intuitive (but more “foolproof”)– generally more expensive– extensive “scene setting” capability– generally more compact (multi-function faders)
Outline – Microphone Selection• Microphone Characteristics• Pickup Patterns• Directional Characteristics• Balanced Lines• Musical Instruments• Musical Instruments• Effects and Rules• Wireless Systems• Frequency Bands and Intermodulation
Effects• Diversity Principle• Antenna Types
Microphone Characteristics• Dynamic
– employs diaphragm/voice coil/magnet assembly
– rugged, relatively inexpensive– can handle large SPL– can handle large SPL– generally unaffected by heat/humidity
Microphone Characteristics• Condenser
– based on an electrically-charged diaphragm/backplate assembly that forms a “sound -sensitive capacitor”
– electric field between diaphragm and backplate is proportional to spacing backplate is proportional to spacing between them
• Maintaining charge– electret: permanent
charge (special material)– non -electret: need
polarizing voltage
Microphone Characteristics• Condenser
– all types require additional active circuitry to create an electrical signal compatible with standard microphone inputs
– requires batteries or phantom power (48 v)
Microphone Characteristics• Transient response
– ability to respond to rapidly changing sound wave (“it’s all about physics”)
– diaphragm assembly of a dynamic microphone may weigh up to 1000x that of a condenser microphonea condenser microphone
Microphone Characteristics• Frequency response
– smoothness of frequency response curve– may be “flat” (“extended”) or “shaped”
Pickup Patterns• Omnidirectional
Pickup Patterns• Cardioid (“heart shaped”)
Pickup Patterns• Supercardioid
Pickup Patterns• Maximizing rear rejection
Directional Characteristics• ambient sound rejection (better with directional
microphones than non-directional)• distance factor (directional microphones have
greater “reach”)• off-axis coloration (less with non-directional
microphones)• proximity effect (bass boost on directional • proximity effect (bass boost on directional
microphones with decreasing distance)• susceptibility to “popping” (inherent in all directio nal
microphones)
Balanced Lines• electrical output of microphones is only a
few millivolts• to reduce noise susceptibility, use shielded,
balanced lines ONLY• braided shield is generally better at EMI
rejection than foil shieldrejection than foil shield
Musical Instruments• need to be aware of frequency range
(including harmonics) and directional output
Effects and Rules• multi-mic comb filtering
Effects and Rules• reflection comb filtering
Effects and Rules• 3-to-1 rule (“the distance between
microphones should be at least 3x the distance from each microphone to its intended sound source”)
Effects and Rules• General
– microphone technique boils down to personal taste (“whatever sounds right isright”)
– there is no one ideal microphone to use on any particular instrument (but there are any particular instrument (but there are “good choices” and “bad choices”)
– use as few microphones as are necessary to get a good sound (remember that every time the number of open microphones doubles, the potential acoustic gain decreases by 3 dB)
Live Microphone Techniques
Live Microphone Techniques
Live Microphone Techniques
Live Microphone Techniques
Live Microphone Techniques
Live Microphone Techniques
Live Microphone Techniques
Live Microphone Techniques
Let’s Play…What’s the Difference?
FM Wireless Systems• Basically a low -power transmitter and radio
receiver combination• Can be VHF/UHF, fixed -frequency or
frequency agile (tunable)
Wireless Frequency Bands
FM Intermodulation Effects
Two Transmitters Three Transmitters
FM Wireless Systems• Desirable characteristics
– UHF less prone to interference than VHF– diversity (dual antenna) receivers less
prone to signal dropout due to interference effects
– frequency synthesis provides tuning – frequency synthesis provides tuning flexibility
– squelch provides protection against noise bursts if signal drops out – “tone-key” preferable
– compatibility groups provide interference-free operation of multiple transmitters/receivers in same venue
FM Diversity Principle
FM Antenna Types
Transmitter
Receiver
Let’s Play…What’s the Difference?
Spread Spectrum Wireless
Outline – Racks and Wiring • Equipment Racks• Rack Issues• Rack Design Software• Sample Rack Layout and Equipment List• Wiring Issues• Wiring Issues
Equipment Rackshttp://www.middleatlantic.com/
http://www.racktools.com/
Rack Issues
• Access (installation and maintenance)• Mechanical support and stability• Ventilation• Cable routing and dressing• Cable routing and dressing
http://www.racktools.com/
Active Crossover (AC22)
Video RF Modulator
Reference Monitor GRQ (M7 & M8)
D-Zone 2 & 3 EQ (ME30)
Main Distribution Amp (DA-2)
<blank>
D-Zone Delay (ART PD3)
Choir & Balc Fill GRQ (Aux 5 & DA 3)
Hot Spot Monitor GRQ (Aux Send 1,2)
Floor Monitor GRQ (Aux Send 3,4)
Sanctuary & Chapel GRQ (DA 1 & 2)
D-Zone & Hear Ast Comp/Lim (dbx-C/L)
D-Zone 1 & Chapel Fill EQ (ME15B)
70V Distrib Amp (P912)
System Power Sequencer
Active Crossover (AC22)
Video RF Modulator
Reference Monitor GRQ (M7 & M8)
D-Zone 2 & 3 EQ (ME30)
Main Distribution Amp (DA-2)
<blank>
D-Zone Delay (ART PD3)
Choir & Balc Fill GRQ (Aux 5 & DA 3)
Hot Spot Monitor GRQ (Aux Send 1,2)
Floor Monitor GRQ (Aux Send 3,4)
Sanctuary & Chapel GRQ (DA 1 & 2)
D-Zone & Hear Ast Comp/Lim (dbx-C/L)
D-Zone 1 & Chapel Fill EQ (ME15B)
70V Distrib Amp (P912)
System Power Sequencer CD Recorder (CDW-33)
CD Player / Cassette Player Combo
System Power Control
CD Recorder (CDW-33)
CD Player / Cassette Player Combo
System Power Control
37U System Rack
24U Console Rack
Protected by locking plexiglass16 U security door
Sample Rack Layout
Sanctuary HF/LF Amp (MT1200)
Chapel HF/LF Amp (MT600)
Floor Mon 1/2 Amp (MT600)
Hot Spot 1/2 Amp (MT600)
D-Zone 2/3 Amp (MT600)
D-Zone 1/Choir Amp (CT400)
Balcony Fill/Chapel Fill (JBL)
<3U Drawer>
Amp Status Monitor
Sanctuary HF/LF Amp (MT1200)
Chapel HF/LF Amp (MT600)
Floor Mon 1/2 Amp (MT600)
Hot Spot 1/2 Amp (MT600)
D-Zone 2/3 Amp (MT600)
D-Zone 1/Choir Amp (CT400)
Balcony Fill/Chapel Fill (JBL)
<3U Drawer>
Amp Status Monitor
UHF Distribution Amp (UA844)
UHF Distribution Amp (UA844)
Dual UHF Wireless Receiver (ULXP4D)
<blank>
Effects Processor (Lexicon)
Dual UHF Wireless Receiver (ULXP4D)
Mixing Console Power Supply
UHF Distribution Amp (UA844)
UHF Distribution Amp (UA844)
Dual UHF Wireless Receiver (ULXP4D)
Dual UHF Wireless Receiver (ULXP4D)
Dual UHF Wireless Receiver (ULXP4D)
Dual UHF Wireless Receiver (ULXP4D)
Record C/L (dBX)
Dual Cassette Recorder (322-II)
UHF Distribution Amp (UA844)
UHF Distribution Amp (UA844)
Dual UHF Wireless Receiver (ULXP4D)
<blank>
Effects Processor (Lexicon)
Dual UHF Wireless Receiver (ULXP4D)
Mixing Console Power Supply
UHF Distribution Amp (UA844)
UHF Distribution Amp (UA844)
Dual UHF Wireless Receiver (ULXP4D)
Dual UHF Wireless Receiver (ULXP4D)
Dual UHF Wireless Receiver (ULXP4D)
Dual UHF Wireless Receiver (ULXP4D)
Record C/L (dBX)
Dual Cassette Recorder (322-II)
for maxed out wireless config = 8 HH + 4 BP
Sample Equipment List
Wiring Issues
• Power conditioning, distribution, and sequencing
• Balanced vs. unbalanced audio cables• XLR vs TRS connectors• XLR vs TRS connectors• Avoiding ground loops, hum, and buzz
A1 A2 A3 A4 A5 A6 A7-A10 M1 M2 M3 M4 M5 M6 M7 M8
GRQ3102
MT600
GRQ3102
MT600
Snake
ReturnsGRQ3102
½ dBX
DA-2
M2500-48
Mic 1-8 Mic 9-16 Mic 17-24 Mic 25-32 Mic 33-40 Mic 41-48 St 1 St 2 St 3 St 4
Cass
Player
Effects
Return
Computer/
Aux
Sample Signal Path Wiring Diagram
Ref MonRec Feeds
Lexicon
St 3
8-Wide “Patch Snakes” CD
Player
dBX C/L
GROUPS:1,2 - Acoustic Instruments3,4 - Electronic Instruments5,6 - Vocalists7,8 - ChoirC - Speaking (Wireless and Podium)
MATRIX:M1 - Main Distribution Amp
M5,6 - Stereo Record MixM7,8 - Reference Monitor
Hot Spot
MonitorsFloor
Monitors
CT400
Choir
Monitors
GRQ3102
AC22
MT1200
Sb121 EVI-28X2 X2Sanctuary
MT600
Sb121 Sx300
Chapel
GRQ3102
Under-
Balcony
D-Zone
ART PD3
MT600
Hospitality
D-Zones
P912
70 V Distrib
AUX Sends:
A1,2 - Hot Spot Monitor
A3,4 - Floor Monitor
A5 - Choir Monitor
A6 - Effects Send
A7-10 - Snake Returns
½ ME15+ ME30
Balcony
Fill
HAT
½ dBX½ ME15
JBL
Chapel
Fill
RF-Mod
Video
Feed
Video
Switcher
Power Sequence Control
Grounding Strategies
Grounding and Shielding Notes (Rane)
What’s in the “?” – Passive Schemes for Connecting Signal Ground to Chassis
Grounding and Shielding Notes (Rane)
Star Ground Scheme for Connecting Signal Ground to Chassis
Grounding and Shielding Notes (Rane)
Recommended Practice
Sound System Interconnection (Rane)
Recommended Practice – Unbalanced to Balanced Using Transformer Isolation
Sound System Interconnection (Rane)
Lots of Other Possibilities…
Sound System Interconnection (Rane)
Recommended