3.2 Audio signal flow

Audio signal flow is the backbone of TV studio production sound. It traces the path from microphones to mixers, through processing and amplification, to final output. Understanding each component's role is crucial for capturing, manipulating, and delivering high-quality audio.

Proper signal management ensures clean sound throughout the chain. This includes setting appropriate levels, using the right connections, and maintaining synchronization. Troubleshooting skills are essential for identifying and resolving issues that can arise at any point in the audio signal flow.

Audio signal chain

• The audio signal chain describes the path an audio signal takes from its source to the final output
• Understanding the audio signal chain is crucial for ensuring high-quality sound in TV studio productions
• Each component in the chain plays a specific role in capturing, processing, and reproducing the audio signal

Microphone to mixer

Top images from around the web for Microphone to mixer

• 

  How to connect a microphone to apply audio signal to electronic circuit? - Electrical ... View original

  Is this image relevant?

• 

  MIC Pre-amplifier - Electronics-Lab.com View original

  Is this image relevant?

• 

  Preamplifier for electret microphone with LM358 opamp - BuildCircuit.COM View original

  Is this image relevant?

• 

  How to connect a microphone to apply audio signal to electronic circuit? - Electrical ... View original

  Is this image relevant?

• 

  MIC Pre-amplifier - Electronics-Lab.com View original

  Is this image relevant?

1 of 3

Top images from around the web for Microphone to mixer

• 

  How to connect a microphone to apply audio signal to electronic circuit? - Electrical ... View original

  Is this image relevant?

• 

  MIC Pre-amplifier - Electronics-Lab.com View original

  Is this image relevant?

• 

  Preamplifier for electret microphone with LM358 opamp - BuildCircuit.COM View original

  Is this image relevant?

• 

  How to connect a microphone to apply audio signal to electronic circuit? - Electrical ... View original

  Is this image relevant?

• 

  MIC Pre-amplifier - Electronics-Lab.com View original

  Is this image relevant?

1 of 3

• Microphones convert acoustic energy into electrical signals
• Different types of microphones (dynamic, condenser, ribbon) are suited for various applications
• Microphone placement and technique affect the captured sound quality
• Microphone signals are typically low-level and require preamplification before reaching the mixer

Mixer functions and routing

• Audio mixers combine and process multiple audio signals
• Mixers allow for adjusting individual channel levels, equalization, and panning
• Routing options enable sending signals to various destinations (recording devices, monitors, effects processors)
• Auxiliary sends and subgroups provide additional control and flexibility in signal management

Mixer to audio processing

• Audio signals from the mixer are often sent to external processing equipment
• Processing can include dynamics control (compression, limiting, gating), equalization, and effects
• Inserting processing equipment in the signal chain allows for fine-tuning the audio characteristics
• Proper gain staging ensures optimal signal levels throughout the processing chain

Audio processing equipment

• Compressors and limiters control dynamic range and prevent overloading
• Equalizers shape the frequency response of the audio signal
• Reverb and delay units add spatial effects and depth to the sound
• Noise gates reduce unwanted background noise during quiet passages

Processing to amplification

• Processed audio signals are sent to amplifiers to increase their power
• Preamplifiers boost low-level signals to line level for further processing or recording
• Power amplifiers drive loudspeakers or headphones
• Matching the output level of processing equipment to the input of amplifiers is essential for clean, undistorted sound

Amplification considerations

• Amplifiers should have sufficient power to drive the connected loudspeakers without clipping
• Impedance matching between amplifiers and loudspeakers optimizes power transfer and prevents damage
• Proper cooling and ventilation are necessary to prevent amplifier overheating and failure
• High-quality amplifiers minimize noise, distortion, and coloration of the audio signal

Amplification to loudspeakers

• Loudspeakers convert electrical signals back into acoustic energy
• Different types of loudspeakers (full-range, subwoofers, monitors) serve specific purposes
• Loudspeaker sensitivity and power handling should match the amplifier's output
• Crossovers split the audio signal into appropriate frequency ranges for multi-speaker systems

Loudspeaker placement

• Proper loudspeaker placement ensures even coverage and minimizes reflections
• Stereo imaging and soundstage are affected by the positioning of left and right speakers
• Subwoofers should be placed to optimize low-frequency response and avoid nulls
• Monitoring loudspeakers should be positioned at ear level and form an equilateral triangle with the listener

Audio monitoring

• Audio monitoring allows engineers, producers, and talent to hear the audio signal at various points in the signal chain
• Proper monitoring ensures that the audio quality meets the desired standards and helps identify any issues
• Different monitoring systems serve specific purposes in the studio environment

Headphone monitoring

• Headphones provide isolated listening for talent, allowing them to hear their own performance and cues
• Closed-back headphones offer better isolation and minimize leakage into microphones
• Headphone amplifiers or distribution systems allow for individual volume control and multiple headphone outputs
• Latency and audio quality should be considered when choosing headphones and amplifiers

Control room monitoring

• Control room monitors allow engineers and producers to critically listen to the audio mix
• Near-field monitors are positioned close to the listener and provide accurate representation of the sound
• Midfield and far-field monitors are used for larger control rooms and provide a broader listening perspective
• Acoustic treatment of the control room is essential for accurate monitoring and minimizing reflections

Studio floor monitoring

• Studio floor monitors (foldback) provide audio for talent and crew during live productions
• In-ear monitors (IEMs) offer personalized mixes and reduce stage volume
• Wedge monitors are placed on the studio floor and provide a shared listening experience
• Proper placement and level control of floor monitors minimize feedback and ensure clear communication

Audio levels

• Audio levels refer to the strength or amplitude of the audio signal at various points in the signal chain
• Proper management of audio levels ensures optimal signal-to-noise ratio, prevents distortion, and maintains consistency
• Different types of audio equipment have specific level standards and requirements

Microphone levels

• Microphone levels are typically low and require preamplification to reach line level
• Proper microphone gain setting prevents clipping and ensures a clean, noise-free signal
• Phantom power (48V) is required for condenser microphones to operate
• Microphone sensitivity and output level should be considered when setting gain

Line levels

• Line level is the standard signal level for audio equipment interconnections
• Professional line level (+4 dBu) is used in studio environments for better noise performance
• Consumer line level (-10 dBV) is found in home audio equipment and some semi-professional gear
• Matching line levels between devices prevents signal degradation and maintains proper gain structure

Amplifier levels

• Amplifier levels should be set to provide sufficient power to loudspeakers without clipping
• Input sensitivity and gain controls on amplifiers allow for matching the incoming signal level
• Output level meters help monitor the amplifier's performance and prevent overloading
• Proper gain staging between the mixer, processing, and amplification stages is crucial for optimal sound quality

Proper gain staging

• Gain staging is the process of setting appropriate levels throughout the audio signal chain
• Each component in the chain should operate within its optimal range to minimize noise and distortion
• Unity gain is achieved when the output level of one device matches the input level of the next
• Proper gain staging maximizes the signal-to-noise ratio and headroom, resulting in a clean and dynamic audio signal

Audio connections

• Audio connections are the physical interfaces between audio devices that allow signal transmission
• Different types of connectors and cable formats are used depending on the application and signal type
• Proper selection and maintenance of audio connections ensure signal integrity and minimize noise and interference

Analog vs digital

• Analog audio connections transmit continuous electrical signals that represent sound waves
• Digital audio connections transmit discrete binary data representing the audio signal
• Analog connections are susceptible to noise and signal degradation over long distances
• Digital connections maintain signal quality and allow for longer cable runs without loss

Balanced vs unbalanced

• Balanced audio connections use three-conductor cables (XLR, TRS) to reduce noise and interference
• Unbalanced connections use two-conductor cables (TS, RCA) and are more susceptible to noise
• Balanced connections are preferred in professional environments for their superior noise rejection
• Unbalanced connections are often used in consumer-grade equipment and short cable runs

XLR connectors

• XLR connectors are the standard for balanced audio connections in professional settings
• They feature a locking mechanism and robust construction for reliable connectivity
• XLR cables are typically used for microphone signals and line-level interconnects
• Male XLR connectors are used for outputs, while female XLR connectors are used for inputs

TRS connectors

• TRS (Tip-Ring-Sleeve) connectors are used for balanced or unbalanced connections
• 1/4" TRS connectors are common in professional audio equipment for line-level signals
• 3.5mm TRS connectors (mini-jacks) are used in consumer-grade devices and headphones
• TRS connectors are versatile and can carry stereo signals or separate left and right channels

RCA connectors

• RCA connectors are unbalanced and commonly used in consumer audio equipment
• They are typically color-coded (red for right, white for left) for stereo connections
• RCA connectors are not recommended for long cable runs or noisy environments
• They are often used for connecting consumer devices to professional equipment using DI boxes

Digital audio interfaces

• Digital audio interfaces (USB, FireWire, Thunderbolt) allow the transfer of digital audio between devices
• They convert analog signals to digital and vice versa, enabling integration with computers and software
• Digital interfaces offer high-quality audio transmission and eliminate the need for additional conversion stages
• Some digital interfaces (ADAT, MADI) allow for the transmission of multiple audio channels over a single cable

Audio synchronization

• Audio synchronization ensures that the audio and video elements of a production are perfectly aligned
• Proper synchronization is essential for maintaining the illusion of reality and preventing distracting lip-sync issues
• Various techniques and technologies are used to achieve and maintain audio-to-video synchronization

Audio to video sync

• Audio should be synchronized with the corresponding video frames to create a coherent experience
• The human brain is sensitive to audio-video misalignment, with tolerances as low as 10-20 milliseconds
• Timecode (LTC, VITC) is used to synchronize audio and video devices in post-production
• Genlock and word clock signals ensure synchronization between audio and video equipment in live productions

Lip sync issues

• Lip sync issues occur when the audio and video of a speaking subject are not properly aligned
• Factors such as video processing delay, audio latency, and transmission delays can cause lip-sync problems
• Lip-sync errors are more noticeable in close-up shots and can be distracting for viewers
• Proper audio-video synchronization and delay compensation are crucial for maintaining lip-sync

Audio delay compensation

• Audio delay compensation is used to align audio with video when processing or transmission delays occur
• Delay can be introduced by video processing, digital audio converters, and transmission systems
• Audio delay units or built-in delay compensation in equipment can be used to match the audio delay to the video
• Measurement and calibration of the audio-video delay are necessary for accurate synchronization

Audio signal quality

• Audio signal quality refers to the overall fidelity and accuracy of the audio signal throughout the production chain
• Factors such as noise, distortion, frequency response, and dynamic range affect the perceived quality of the audio
• Proper equipment selection, setup, and maintenance are essential for achieving high-quality audio

Signal-to-noise ratio

• Signal-to-noise ratio (SNR) is the measure of the desired audio signal level relative to the noise floor
• A higher SNR indicates a cleaner audio signal with less background noise
• Proper gain staging, balanced connections, and high-quality equipment contribute to a better SNR
• Adequate SNR is essential for capturing and reproducing clear, detailed audio

Dynamic range

• Dynamic range is the difference between the loudest and quietest parts of an audio signal
• A wide dynamic range allows for the preservation of subtle details and the impact of loud moments
• Compression and limiting can be used to control the dynamic range for specific applications
• Sufficient dynamic range is necessary to avoid clipping and maintain audio fidelity

Frequency response

• Frequency response describes how an audio system or component reproduces different frequencies
• A flat frequency response indicates that all frequencies are reproduced equally, without emphasis or attenuation
• Microphones, speakers, and other equipment have specific frequency response characteristics that affect the sound
• Equalizers can be used to adjust the frequency response and compensate for any deficiencies

Total harmonic distortion

• Total harmonic distortion (THD) is a measure of the nonlinear distortion introduced by audio equipment
• Lower THD values indicate a cleaner, more accurate audio signal
• Overloading, clipping, and poor equipment design can contribute to higher THD levels
• Monitoring and minimizing THD helps maintain the clarity and transparency of the audio signal

Troubleshooting audio issues

• Audio issues can arise at various points in the signal chain, affecting the quality and reliability of the sound
• Systematic troubleshooting approaches help identify and resolve problems efficiently
• Common audio issues include noise, hum, level mismatches, feedback, and digital glitches

Identifying signal chain problems

• Start by isolating the problem to a specific component or section of the signal chain
• Check connections, cables, and equipment settings to ensure proper configuration
• Use signal generators and test equipment to trace the signal path and identify the source of the issue
• Systematically bypass or substitute components to pinpoint the faulty element

Solving noise and hum

• Noise and hum can be caused by ground loops, electromagnetic interference, or faulty equipment
• Use balanced connections and high-quality cables to minimize noise pickup
• Ensure proper grounding and avoid creating ground loops by using isolation transformers or DI boxes
• Identify and relocate equipment or cables that may be introducing electromagnetic interference

Fixing level mismatches

• Level mismatches can occur when connecting equipment with different nominal levels or improper gain staging
• Use level matching devices (pads, attenuators, DI boxes) to balance the signal levels between components
• Adjust gain settings on equipment to ensure proper level matching and avoid clipping or distortion
• Monitor levels throughout the signal chain to maintain optimal gain structure

Dealing with feedback

• Feedback occurs when a microphone picks up its own amplified signal, creating a loop
• Position microphones and speakers to minimize the potential for feedback
• Use directional microphones and place them close to the sound source to reduce pickup of ambient sound
• Apply equalization to reduce the gain at specific frequencies prone to feedback
• Employ feedback suppressors or automatic feedback control systems for problematic situations

Resolving digital audio glitches

• Digital audio glitches can manifest as pops, clicks, or dropouts in the audio signal
• Ensure that all digital devices are properly synchronized using a master clock or timecode
• Check sample rates and bit depths to ensure compatibility between digital components
• Use high-quality, low-jitter digital cables and maintain secure connections
• Optimize computer settings and buffer sizes to minimize audio processing issues in digital audio workstations (DAWs)