Download Buying the right PA for your band and building

Buying the right PA for your
band and building
Glyn Chapman
Acoustic Arrangements
Needs Analysis
•
•
•
•
•
•
•
•
Who’s it for?
What’s it for?
Who’s going operate it?
What worship styles?
For now or for the future?
Plan for occasional needs.
What about video, lighting & electrics.
What best serves the vision of the Church.
The Sound System
Basic System
•Source
•Mixer
•Amplifier
•Loudspeaker
Inputs
• Microphones
Dynamic (moving coil)
Condenser
Pick-Up Pattern
Style
• DI Boxes (direct injection)
Active/Passive
Electro-Acoustics, Keyboard, Bass
• Radio Mics, CD, DVD, PC
Cables, Connectors, Multicore
• Balanced Cable
Cables, Connectors, Multicore
• XLR
pin 1 gnd, pin 2 +ve (hot), pin 3 -ve (cold)
• JACK
TRS: tip, ring sleeve (stereo jack)
as balanced: tip +ve, ring -ve, sleeve gnd
• To unbalance: link gnd & -ve
Cables, Connectors, Multicore
• Multicore:
How many sends?
How many returns?
How long?
Mixer
• Analogue ‘v’ Digital
Number of inputs (channels)
EQ
Routing: Auxiliaries
Powered or Unpowered
Processors
• Effects: Reverb, Chorus, Delay
• Compressor/Limiters
• Gates
• Graphic Equalisers
• Crossovers
• Speaker Controllers
Amplifiers
• Constant Voltage 100v Line
Speaker load not exceed 75% of amp
power.
• Low Impedance
Example:
500w into 4ohm
= 300w into 8ohm
= 700w into 2ohm
Allow for headroom
up to twice speaker power
Speakers
• Power: RMS = Continuous
Program = 2 x Continuous
Peak = 4 x Continuous
• Sensitivity: SPL – Sound Pressure Level
Ex: 400w 96dB speaker is same level
as 200w 99dB speaker
I.e. you need twice the power for 3dB
increase in level
• Add 2nd speaker adds 3dB or 6dB if placed
together
Speakers
• Inverse Square Law: -6 dB per distance
doubled
•
•
•
•
Dispersion
Low Impedance/100v Line
Line Array
Horn Loaded
Speakers
Top Tips
•
•
•
•
•
•
Listen to advice from professionals
Check your cables & connectors
Throw away old, broken or unusable kit
Use your ears
Check your mid range EQ
Don’t buy something just because it’s on
offer
• Buy the right product for the job
• Cost is part of the specification
www.a-a.uk.com