3.3 Equalizers and compressors
12 min read•august 20, 2024
Audio processing is crucial in TV studio production. Equalizers shape frequency response, allowing engineers to boost or cut specific ranges for desired tonal balance. Different types offer varying control levels, from graphic to parametric and shelving equalizers.
Compressors control , reducing loud sounds and boosting quiet ones for consistent audio. Types include VCA, optical, FET, and tube compressors, each with unique characteristics. Understanding key parameters like , , and attack/release times is essential for effective dynamic control.
Types of equalizers
- Equalizers are essential tools in TV studio production for shaping the frequency response of audio signals
- They allow engineers to boost or cut specific frequency ranges to achieve the desired tonal balance
- Different types of equalizers offer varying levels of control and flexibility
Graphic equalizers
Top images from around the web for Graphic equalizers
Rainbow Graphic Equalizer by Evolventity on DeviantArt View original
Is this image relevant?
File:Graphic equalizer.jpg - Wikipedia View original
Is this image relevant?
5-Band Graphic Equalizer - Electronics-Lab.com View original
Is this image relevant?
Rainbow Graphic Equalizer by Evolventity on DeviantArt View original
Is this image relevant?
File:Graphic equalizer.jpg - Wikipedia View original
Is this image relevant?
1 of 3
Top images from around the web for Graphic equalizers
Rainbow Graphic Equalizer by Evolventity on DeviantArt View original
Is this image relevant?
File:Graphic equalizer.jpg - Wikipedia View original
Is this image relevant?
5-Band Graphic Equalizer - Electronics-Lab.com View original
Is this image relevant?
Rainbow Graphic Equalizer by Evolventity on DeviantArt View original
Is this image relevant?
File:Graphic equalizer.jpg - Wikipedia View original
Is this image relevant?
1 of 3
- Consist of a series of fixed-, typically ranging from 7 to 31 bands
- Each band has a slider or fader that allows boosting or cutting the gain at that specific frequency
- Provide a visual representation of the frequency spectrum, making it easy to identify and adjust problem areas
- Commonly used for quick and intuitive adjustments to the overall tonal balance (live sound reinforcement)
Parametric equalizers
- Offer more precise control over the frequency spectrum compared to graphic equalizers
- Allow adjusting the center frequency, gain, and bandwidth () of each band
- Typically feature fewer bands than graphic equalizers, but each band is fully adjustable
- Ideal for surgical EQ adjustments, such as removing specific resonances or feedback frequencies (post-production)
Shelving equalizers
- Designed to boost or cut frequencies above or below a specific frequency point
- High-shelf equalizers affect frequencies above the cutoff point, while low-shelf equalizers affect frequencies below the cutoff point
- Useful for broad tonal shaping, such as adding brightness or warmth to an audio signal
- Often used in conjunction with other equalizer types to fine-tune the overall frequency balance (mastering)
Equalizer parameters
- Understanding the key parameters of equalizers is crucial for effective audio processing in TV studio production
- These parameters allow engineers to precisely control the frequency response of audio signals
Frequency bands
- Represent the range of frequencies that an equalizer can adjust
- Measured in Hertz (Hz) and typically divided into low, mid, and high-frequency ranges
- The number of frequency bands varies depending on the type of equalizer (graphic equalizers have fixed bands, while parametric equalizers allow customizable bands)
- Choosing the appropriate frequency band is essential for targeting specific areas of the frequency spectrum
Gain control
- Determines the amount of boost or cut applied to a specific frequency band
- Measured in decibels (dB), with positive values indicating a boost and negative values indicating a cut
- The range of gain adjustment varies depending on the equalizer, but typically spans from -15 dB to +15 dB
- Adjusting the gain allows engineers to emphasize or de-emphasize certain frequencies to achieve the desired tonal balance
Q factor or bandwidth
- Refers to the width of the frequency range affected by an equalizer band
- A higher Q factor results in a narrower bandwidth, affecting a smaller range of frequencies around the center frequency
- A lower Q factor results in a wider bandwidth, affecting a broader range of frequencies
- Parametric equalizers allow adjusting the Q factor, providing more precise control over the affected frequency range
- Adjusting the Q factor enables engineers to target specific frequencies without affecting neighboring frequencies
Applications of equalizers
- Equalizers are versatile tools with numerous applications in TV studio production
- They play a crucial role in shaping the tonal balance of audio signals to achieve the desired sound
Correcting frequency imbalances
- Equalizers can be used to compensate for frequency imbalances caused by suboptimal recording environments or equipment limitations
- By identifying and adjusting problematic frequency ranges, engineers can create a more balanced and natural-sounding audio signal
- Examples include reducing excessive low-end rumble or taming harsh high frequencies
Enhancing specific frequencies
- Equalizers allow engineers to emphasize certain frequency ranges to achieve a desired effect or tonal character
- Boosting specific frequencies can add clarity, presence, or warmth to an audio signal
- Examples include adding brightness to a vocal track or enhancing the low-end punch of a kick drum
Reducing unwanted noise
- Equalizers can be used to attenuate or remove unwanted noise or resonances from an audio signal
- By identifying and cutting specific frequency ranges, engineers can minimize background noise, hum, or feedback
- Examples include reducing the hiss from a noisy recording or eliminating a specific feedback frequency in a live sound reinforcement setup
Types of compressors
- Compressors are essential dynamics processing tools in TV studio production for controlling the dynamic range of audio signals
- They reduce the level of loud sounds and boost quieter sounds, creating a more consistent and balanced audio output
- Different types of compressors offer unique characteristics and tonal qualities
VCA compressors
- Voltage-Controlled Amplifier (VCA) compressors use a control voltage to adjust the gain reduction
- Known for their fast, clean, and transparent , making them suitable for a wide range of applications
- Offer precise control over the compression parameters, allowing engineers to fine-tune the dynamic response
- Commonly used for controlling the dynamic range of individual instruments or entire mixes (dbx 160A)
Optical compressors
- Use a light-dependent resistor (LDR) and an electroluminescent panel to control the gain reduction
- Characterized by their smooth, musical, and natural-sounding compression
- Slower attack and release times compared to other compressor types, resulting in a more gradual and unobtrusive compression
- Often used for gentle dynamic control on vocals, bass, and master bus processing (Teletronix LA-2A)
FET compressors
- Field-Effect Transistor (FET) compressors use a transistor to control the gain reduction
- Known for their fast attack times and punchy, aggressive sound
- Capable of adding character and coloration to the audio signal, making them popular for drum processing and parallel compression
- Commonly used for adding punch and attitude to individual instruments or drum busses (UREI 1176)
Tube compressors
- Incorporate vacuum tubes in their gain reduction circuitry, imparting a warm, rich, and harmonically-pleasing sound
- Slower attack and release times compared to solid-state compressors, resulting in a smooth and musical compression
- Often used for adding warmth and character to vocals, bass, and master bus processing
- Highly sought-after for their vintage tone and ability to "glue" mix elements together (Fairchild 670)
Compressor parameters
- Understanding the key parameters of compressors is essential for effective dynamic range control in TV studio production
- These parameters allow engineers to shape the dynamic response of audio signals to achieve the desired balance and impact
Threshold
- Determines the level at which the compressor starts applying gain reduction
- Measured in decibels (dB), with lower thresholds resulting in more compression and higher thresholds resulting in less compression
- Setting the threshold appropriately is crucial for achieving the desired amount of dynamic control without over-compressing the signal
Ratio
- Defines the amount of gain reduction applied to the audio signal once it exceeds the threshold
- Expressed as a ratio (2:1, 4:1, etc.), with higher ratios resulting in more aggressive compression
- A ratio of 4:1 means that for every 4 dB the input signal exceeds the threshold, the output level will only increase by 1 dB
- Choosing the appropriate ratio depends on the desired amount of dynamic control and the characteristics of the audio material
Attack time
- Determines how quickly the compressor reacts to the input signal once it exceeds the threshold
- Measured in milliseconds (ms), with faster attack times resulting in a more immediate gain reduction
- Slower attack times allow transients and initial peaks to pass through unaffected, preserving the natural attack of the audio signal
- Adjusting the allows engineers to shape the transient response and overall character of the compressed signal
Release time
- Defines how quickly the compressor returns to its normal gain level once the input signal falls below the threshold
- Measured in milliseconds (ms) or seconds (s), with faster release times resulting in a more rapid return to the uncompressed state
- Slower release times can create a smoother and more natural-sounding compression, preventing abrupt level changes
- Setting the too fast can result in pumping or breathing artifacts, while setting it too slow can cause the compressor to remain engaged for too long
Knee
- Refers to the transition point between the uncompressed and compressed states of the audio signal
- A soft allows for a gradual transition into compression, resulting in a more musical and natural-sounding gain reduction
- A hard knee provides an abrupt transition into compression, resulting in a more aggressive and noticeable gain reduction
- Adjusting the knee allows engineers to fine-tune the compressor's response to the input signal and achieve the desired character
Makeup gain
- Compensates for the overall level reduction caused by the compressor
- Measured in decibels (dB), with positive values increasing the output level of the compressed signal
- Applying allows engineers to maintain a consistent output level after compression, ensuring the audio signal sits at the desired place in the mix
- Proper makeup gain adjustment is essential for maintaining the balance between compressed and uncompressed elements in a mix
Compressor applications
- Compressors are versatile tools with numerous applications in TV studio production
- They play a crucial role in controlling dynamics, enhancing sustain, and preventing overloading
Controlling dynamic range
- Compressors can be used to reduce the dynamic range of an audio signal, making quieter parts more audible and louder parts less overpowering
- By evening out the levels, compressors create a more consistent and balanced sound
- Examples include applying compression to a vocal track to maintain intelligibility throughout the performance or compressing a bass guitar to achieve a more solid and stable low-end
Enhancing sustain
- Compressors can be used to increase the sustain of instruments or sounds by reducing the rate at which they decay
- By applying compression with a slow release time, engineers can make notes or chords ring out longer, adding depth and richness to the sound
- Examples include compressing a guitar solo to make the notes more prominent and prolonged or applying compression to a piano to enhance the natural sustain of the instrument
Preventing overloading
- Compressors can be used as a safeguard to prevent audio signals from exceeding a certain level and causing distortion or clipping
- By setting the threshold and ratio appropriately, engineers can ensure that the output level remains within a safe range, even if the input signal experiences sudden peaks
- Examples include using a compressor on a master bus to prevent overloading during live broadcasting or applying compression to a drum submix to control the overall level and prevent clipping
Sidechaining techniques
- Sidechaining involves using an external audio signal to control the compression of the main audio signal
- This technique allows the compressor to react to the dynamics of the external signal rather than the main signal itself
- Examples include using a kick drum to trigger compression on a bass guitar, creating space for the kick in the mix, or using a lead vocal to "duck" the level of background instruments during vocal passages
Equalizer vs compressor
- Equalizers and compressors are two distinct types of audio processing tools, each serving a specific purpose in TV studio production
- Understanding the differences between equalizers and compressors is essential for effective audio processing and achieving the desired sound
Frequency vs amplitude
- Equalizers primarily focus on adjusting the frequency balance of an audio signal
- They allow engineers to boost or cut specific frequency ranges to shape the tonal characteristics of the sound
- Compressors, on the other hand, focus on controlling the dynamic range or amplitude of an audio signal
- They reduce the level of loud sounds and boost quieter sounds to create a more consistent and balanced output
Shaping tone vs controlling dynamics
- Equalizers are used to shape the tonal balance of an audio signal by emphasizing or de-emphasizing certain frequencies
- They can be used to correct frequency imbalances, enhance specific frequencies, or reduce unwanted noise
- Compressors are used to control the dynamic range of an audio signal by reducing the level difference between loud and quiet parts
- They can be used to even out levels, enhance sustain, prevent overloading, and create various effects through sidechaining techniques
Best practices
- Following best practices when using equalizers and compressors is crucial for achieving optimal results in TV studio production
- These practices help ensure a clean, balanced, and professional-sounding audio output
Proper gain staging
- Gain staging involves setting the appropriate levels at each stage of the audio signal chain to maintain optimal signal-to-noise ratio and prevent clipping
- When using equalizers and compressors, it's essential to adjust the input and output levels to avoid overloading or introducing unnecessary noise
- Proper gain staging allows for more and cleaner processing, resulting in a higher-quality audio signal
Avoiding over-compression
- Over-compression occurs when a compressor is applied too aggressively, resulting in a squashed, lifeless, or unnatural sound
- To avoid over-compression, start with a higher threshold and lower ratio, and gradually adjust the settings until the desired amount of dynamic control is achieved
- Listen carefully to the compressed signal and ensure that it retains its natural character and transient response
Matching equalizer and compressor settings
- When using equalizers and compressors together, it's important to consider how their settings interact and affect the overall sound
- Equalizing before compression can alter the way the compressor reacts to the input signal, while equalizing after compression can help shape the tonal balance of the compressed signal
- Experiment with different combinations of equalizer and compressor settings to find the most suitable approach for each situation
Using equalizers and compressors in series
- Applying equalizers and compressors in series (one after another) can provide more control and flexibility over the audio processing
- For example, using an equalizer to shape the tonal balance before applying compression can help the compressor respond more consistently to the input signal
- Using a compressor to control dynamics before applying can help maintain a more balanced frequency response throughout the dynamic range of the signal
- Experiment with different processing orders and settings to achieve the desired sound and optimize the audio processing chain
Common equalizer and compressor issues
- When using equalizers and compressors in TV studio production, engineers may encounter various issues that can negatively impact the audio quality
- Identifying and addressing these issues is crucial for maintaining a professional and polished sound
Excessive noise
- Equalizers and compressors can sometimes introduce or amplify noise in the audio signal, particularly when applying extreme settings or boosting high frequencies
- To minimize noise, ensure proper gain staging, use high-quality equipment, and apply processing judiciously
- If noise becomes an issue, consider using noise reduction techniques or adjusting the equalizer and compressor settings to find a better balance between processing and noise levels
Unnatural sound
- Over-processing with equalizers and compressors can result in an unnatural or artificial-sounding audio signal
- This can occur when applying extreme frequency boosts or cuts, using overly aggressive compression settings, or stacking multiple processors without careful consideration
- To maintain a natural sound, use equalizers and compressors sparingly, and focus on making subtle adjustments that enhance the audio without drastically altering its character
- Regularly compare the processed signal to the original, unprocessed signal to ensure that the processing is not detracting from the overall sound quality
Pumping or breathing artifacts
- Pumping and breathing are common artifacts that can occur when using compressors with fast attack and release times or high compression ratios
- These artifacts are characterized by an audible "pumping" or "breathing" effect, where the background noise or ambience is unnaturally affected by the compression
- To minimize pumping and breathing, adjust the compressor's attack and release times to allow for a more gradual and natural gain reduction
- Experiment with lower compression ratios and higher thresholds to achieve a more transparent and unobtrusive compression
- If pumping or breathing artifacts persist, consider using a different type of compressor or adjusting the sidechain filtering to reduce the compressor's sensitivity to specific frequencies
Key Terms to Review (28)
Attack Time: Attack time is the duration it takes for a compressor or an audio processor to respond to an incoming audio signal after it exceeds a certain threshold level. This parameter is crucial in shaping the dynamics of sound by controlling how quickly the device reduces the volume of the audio signal, effectively smoothing out peaks and enhancing the overall sound quality. By adjusting the attack time, audio engineers can influence how a sound is perceived, impacting everything from punchy drum hits to smooth vocal performances.
Compression: Compression is a dynamic range control technique used in audio production to reduce the difference between the loudest and softest parts of an audio signal. By managing these levels, compression helps to create a more balanced and polished sound, which is essential for effective audio signal flow, mixing, and overall sound design.
De-esser: A de-esser is a specialized audio processing tool designed to reduce sibilance, the harsh 's' and 'sh' sounds in recorded audio. It operates by detecting these high-frequency sounds and applying dynamic compression specifically to those frequencies, smoothing out the vocal track without compromising the overall quality. This helps achieve a more balanced sound, particularly in vocal recordings, where excessive sibilance can be distracting or unpleasant.
Dynamic Range: Dynamic range refers to the difference between the loudest and quietest sounds or signals that a system can handle or reproduce. In audio and video production, it plays a crucial role in ensuring that both soft and loud sounds are captured effectively without distortion, and it influences how images are represented in terms of brightness and contrast. Understanding dynamic range is essential for achieving balanced audio levels, clear visuals, and an overall polished production quality.
Eddie Kramer: Eddie Kramer is a renowned audio engineer and producer, known for his innovative work in the recording industry, particularly during the late 1960s and 1970s. He is famous for his contributions to iconic albums and artists, utilizing equalizers and compressors to shape the sound of rock music. Kramer's techniques have influenced countless sound engineers and producers, making him a pivotal figure in the evolution of studio production.
Equalization: Equalization is the process of adjusting the balance between frequency components within an audio signal to enhance or reduce specific frequencies. It plays a vital role in shaping sound quality by allowing audio engineers to tailor the tonal balance, making it crucial for achieving clarity and impact in various audio applications, including mixing, sound design, and post-production.
Fet compressor: A FET (Field Effect Transistor) compressor is a type of audio dynamic processor that uses FET technology to control the dynamics of audio signals. It operates by reducing the volume of audio signals when they exceed a certain threshold, allowing for a smoother, more controlled sound. This technology is known for its fast response times and the ability to create a warm and musical compression effect, making it popular in music production and broadcasting.
Frequency Bands: Frequency bands refer to specific ranges of frequencies within the audio spectrum that can be adjusted or processed in various ways, particularly by equalizers and compressors. These bands allow audio engineers to manipulate sound by boosting or cutting specific frequency ranges, ultimately shaping the tonal quality of audio signals. Understanding frequency bands is essential for achieving clarity and balance in audio production, whether in music or broadcasting.
Gain Control: Gain control refers to the adjustment of the audio signal's strength or amplitude to achieve the desired level of loudness without introducing distortion. This concept is essential for maintaining audio quality, particularly when using equalizers and compressors, which shape the sound by manipulating frequency balance and dynamic range. Proper gain control ensures that signals remain within optimal levels for processing, preventing clipping and allowing for clearer, more balanced audio output.
George Massenburg: George Massenburg is a prominent audio engineer and producer known for his innovative approaches to recording and mixing techniques, particularly in the realm of live sound and studio production. His contributions to audio signal processing, particularly the development of parametric equalizers and dynamics processing tools, have significantly influenced modern audio engineering practices and technology.
Graphic Equalizer: A graphic equalizer is an audio processing tool that allows users to adjust the frequency response of an audio signal across multiple frequency bands, typically displayed in a visual format with sliders or knobs. This device is crucial for shaping sound by boosting or cutting specific frequencies, which helps to enhance audio clarity and balance in a mix. By using a graphic equalizer, sound engineers can tailor audio output to suit various environments or preferences, making it an essential component in both live sound and studio settings.
Headroom: Headroom refers to the space above the subject's head in a shot or the maximum level of a signal before distortion occurs in audio production. In visual media, proper headroom ensures that subjects are framed attractively and that the composition is balanced, while in audio, having adequate headroom prevents clipping and maintains sound quality during mixing and mastering.
Knee: In audio production, the term 'knee' refers to the point at which a compressor begins to apply gain reduction to an audio signal. This is crucial because it determines how the compressor responds to signals that exceed a set threshold, allowing for smoother transitions and more natural sound. The knee can be characterized as either hard or soft, influencing how aggressively the compressor interacts with the audio signal as it crosses that threshold.
Limiter: A limiter is an audio processing tool that prevents the amplitude of a signal from exceeding a specified threshold, thereby controlling the dynamic range of audio signals. By effectively 'limiting' peaks, it ensures that the output level stays within a desired range, preventing distortion or clipping. Limiters are essential for maintaining audio quality in both live sound and recorded media, making them a critical feature in equalizers and compressors.
Makeup gain: Makeup gain refers to an increase in the level of an audio signal that compensates for the loss of volume due to processing effects, particularly from equalizers and compressors. It allows the overall loudness of a sound signal to be restored or adjusted after it has been altered by dynamics processing, ensuring that the final output remains at an appropriate level. Makeup gain is essential for maintaining audio balance and preventing any unintended drops in volume during mixing or mastering processes.
Multi-band compression: Multi-band compression is a dynamic range processing technique that divides an audio signal into multiple frequency bands, allowing for independent compression of each band. This allows sound engineers to control the dynamics of specific frequency ranges more precisely, enhancing clarity and balance in a mix. By targeting different frequency areas, this tool can be especially useful in managing complex audio content without affecting the overall mix too harshly.
Optical Compressor: An optical compressor is a type of audio processor that uses a light-sensitive element to control the dynamic range of an audio signal. This device reacts to the amplitude of the sound wave and adjusts the gain accordingly, allowing for smoother dynamics and preventing distortion. It’s often favored for its natural-sounding compression, which helps maintain the character of the audio while controlling volume peaks.
Parametric Equalizer: A parametric equalizer is an audio processing tool that allows users to adjust the frequency response of an audio signal with precision. It gives control over specific frequency bands, enabling adjustments to gain, bandwidth, and center frequency. This level of customization makes it especially useful for correcting issues in sound recordings or shaping audio to achieve a desired tonal balance.
Q Factor: The Q factor, or Quality factor, is a parameter that describes the selectivity or bandwidth of a filter, such as those used in equalizers and compressors. A higher Q factor indicates a narrower bandwidth, which allows for more precise control over specific frequency ranges, while a lower Q factor means a wider bandwidth, affecting a broader range of frequencies. This concept is crucial for shaping sound and managing dynamic range in audio production.
Ratio: In audio production, a ratio is a comparison of levels between the input and output of a signal processing device like an equalizer or compressor. This term is crucial because it defines how much a signal will be altered based on the settings applied, influencing dynamics and tonal balance in the sound mix. Understanding the ratio helps in achieving desired audio effects by controlling the amount of gain reduction or enhancement applied to specific frequencies or overall dynamics.
Release Time: Release time refers to the duration it takes for a compressor to stop compressing audio after the input signal falls below the threshold level. This parameter is crucial for controlling how a sound fades back to its original level after being compressed. Understanding release time helps achieve smoother audio dynamics and prevents unnatural sounds during transitions.
Shelving Equalizer: A shelving equalizer is an audio processing tool used to adjust the frequency response of an audio signal by boosting or cutting frequencies above or below a specified threshold. This type of equalizer typically operates on two frequency bands, one for low frequencies and one for high frequencies, allowing for a smooth transition and control over tonal balance in sound production.
Sidechain Compression: Sidechain compression is a dynamic audio processing technique where the output level of one audio signal is controlled by the input level of another signal. This method is often used to create a pumping effect, particularly in electronic music, by allowing the bass or kick drum to cut through a mix while controlling the level of competing sounds. It is a powerful tool for managing the balance and clarity of different elements within a mix.
Signal Conditioning: Signal conditioning refers to the process of manipulating an analog signal in a way that prepares it for the next stage of processing. This includes processes such as amplification, filtering, and converting signals to make them suitable for digital processing or display. By ensuring the signal is clean and at the right level, signal conditioning enhances the quality and reliability of audio and video signals, making it essential for effective sound and image production.
Sound shaping: Sound shaping is the process of modifying audio signals to achieve a desired tonal quality and dynamics. This involves using tools like equalizers and compressors, which allow sound engineers to enhance certain frequencies or control the loudness of audio, creating a more polished and impactful listening experience. By adjusting these elements, sound shaping helps in crafting the final sound that meets artistic intentions and technical requirements.
Threshold: In audio processing, the threshold is the level at which a particular effect, such as compression or equalization, becomes active. It determines when signals will be affected by the processing applied, playing a critical role in shaping the dynamics of sound. Understanding how to set the threshold correctly can significantly impact the overall mix and clarity of audio.
Tube compressor: A tube compressor is an audio processing device that uses vacuum tubes to control the dynamic range of a sound signal, resulting in a warmer and more natural tonal quality. This type of compressor is valued for its ability to add harmonic distortion, which can enhance the richness and character of recordings. Tube compressors are often used in music production to achieve smooth compression and preserve the integrity of the original sound.
VCA Compressor: A VCA (Voltage Controlled Amplifier) compressor is a type of dynamic range processor that uses a voltage-controlled amplifier to adjust the gain of an audio signal based on its amplitude. This allows for precise control over the dynamics of sound, enabling engineers to achieve consistent levels and smoother mixes. The VCA compressor is known for its ability to respond quickly to changes in input levels, making it ideal for both live sound and studio applications.