The Recording Studio

1
The Recording Studio

• Equipment, Power and Connections

2
Physical Layout

• Recording room
• Control room
• Machine room
• Electrical connections
• Power
• Hardwired signal
• Softwired signal

3
Equipment

• Mechnical equipment (machines)
• Noisy, moving parts, with fans
• Put into machine room
• Non-mechanical equipment

4
Console

• 3 sections
• Input section input and signal processing
• Monitor section live input or recorded input
• Center section main control
• Console modes
• Microphone (record) mode
• Line (mix) mode
• Buses direct each channel to a recording track

5
Patch Bay

• Central access for channels on console and input
  and output of outboard equipment ( signal
  processing)
• Some channels have normaled signal routes
• Normal (hardwired) signal routes can be rerouted
  at the patch bay
• Full normal patch points break the normal route
• Half normal patch points allow the normal route

6
The Outboard

• Everything not housed in console
• Standard outboard equipment hardwired to the
  patch bay
• Equalizers, limiters, delays, samplers, echo
  plates, reverbs
• Other recording, mixing or monitoring equipment

7
Speakers

• In control room to monitor
• Placed equi-distance towards center of console
• In studio, not to be picked up by microphone, one
  is out of phase with other

8
Microphones

• -80dBv to -10dBv
• Different frequency ranges
• Large amplification needed, any noise from
  microphone end is amplified too.
• Thermal noise ( heat) in mircophone
• Carbon, capacitor, moving coil, ribbon,
  piezoelectric, eletret.

9
Matching Mike to Person

• Carbon -20 to 0 dBV/ Pa
• Capacitor -50 to -25 dBV/ Pa
• Dynamic -60 to -50 dBV/ Pa
• Piezoelectric -40 to -20 dBV/ Pa
• dB/Pa dB per pascal of air pressure on
• microphone

10
Amplifiers

• Amp part and speaker part
• Isolated from recording studio
• Isolated in isolation boothes or with baffles
• Amp part connected directly to console channel

11
Cable Routing

• Softwired keep it neat, keep it short
• Excessive wire rolled into coil is an inductor
• Power and signal cables should NOT be near each
  other ( when crossing power and signal cables
  cross at right angles)

12
Supplying the Power

• 120 V AC 60 Hz from external supply
• The high voltage power cables near low voltage
  signal cables can cause 60 Hz hum.
• Keep them as far apart as possible
• Hardwared cables are kept in troughs on or in
  studio walls, power and signal in separate
  troughs.

13
Supplying the Power

• Power can be filtered at building entry point to
  reduce external noise ( clean power)
• usually dirty power and lighting runs placed up
  high, and clean power down low.
• Audio cable often is run in the middle of the
  wall at a convenient height for connection boxes.

14
Safety

• Use Residual Current contact Breakers (RCB or
  ELCB)
• 30mA are normal, 10mA are better
• Power outages happen, backup generator is a good
  idea

15
Grounding

• Provides a closed loop for the electrical circuit
• And a 0 volt point of reference
• A huge absorber or supplier of electrons (the
  earth)
• Each building has a rod hammered into ground
  where the building ground is attached

16
Grounding Problems

• All outlets are connected to the grounding rod
  with a copper wire ( has some resistance)
• Outlet ground can be induced with a small
  potenial voltage by EM waves (EMI).
• Different outlets (and therefore equipment) can
  be at different ground potential voltages
• Currents in ground loops can cause humming (60
  Hz) in signal

17
Grounding

• Ideally plug all equipment into the same circuit
  box
• Or use a star ground system for all plugs
• Grounding problems can be fixed by
• pulling equipment down to ground ( flipping
  ground switch on a DI or connecting an instrument
  to a ground with a aligator clip)
• Floating equipment by using a Ground Lifter
  between power plug and outlet

18
EMI on cables

• Twisted pair cable

19
Unbalanced Connection

• Cable shield and equipment connected to chasis
  ground
• Exernal ground in star configuration

20
Transformer Isolation

• No Ground loop

21
Balanced connection

• Cable ground connected to circuit ground

22
Star Grounding

• Shielded Cable Induced Noise

23
Unbalanced to Balanced Cable
24
Balanced and Unbalanced Connectors
25
Types of Signals

• Analog audio
• Digital
• Video

26
Analog Audio

• Bandwidth - 20 Hz to 20K Hz
• Minimum wavelength 16 km
• Normal cable length (5 m) is a very small
  fraction of minimum wavelength
• Shielded and unshielded cable used, twisted pair
  reduces EMI
• No problems with cable length
• Emitts least amount of EM field of the three
  signal types

27
Digital Signals

• Bandwidth - to 25M Hz
• Minimum wavelength 10 m
• Normal cable length (5 m) is a very large
  fraction of minimum wavelength
• Shielded twisted pairs cable reduces EMI
• Keep cable length very short
• Emitts largest amount of EM field of the three
  signal types

28
Video Signals

• Bandwidth - to 6M Hz
• Minimum wavelength 50 m
• Normal cable length (5 m) is a small fraction of
  minimum wavelength
• Coaxial cable normally used to shield from EMI
• Emitts EM field

29
Fault Report

• ID Session, date, time, studio
• ID engineer and assist
• Describe symptoms very explicitly
• Describe temperary action taken
• ID repair guy date
• Diagnosis what was wrong
• Parts ordered, date
• Parts received, date