Audio EQ calculator • 2026 sound tools
\( G(f) = 20 \log_{10}\left(\frac{A_{out}(f)}{A_{in}(f)}\right) \)
Where:
This formula calculates the gain applied by an equalizer at a given frequency.
Common EQ Bands:
Example: If an EQ boosts a signal from 1V to 1.414V at a specific frequency:
\( G(f) = 20 \log_{10}(1.414/1) = 20 \log_{10}(1.414) = 3 \text{ dB} \)
Thus, the gain is +3 dB at that frequency.
Equalization (EQ) is the process of adjusting the balance between frequency components within an electronic signal. In audio production, EQ is used to enhance or reduce specific frequency ranges to achieve desired tonal characteristics. It's essential for mixing, mastering, and correcting frequency imbalances in recordings.
The gain applied by an equalizer is calculated using:
Where:
Equalization - adjusting frequency balance in audio signals.
\(G(f) = 20 \log_{10}(A_{out}/A_{in})\)
Where G=gain in dB, A=out/in amplitudes.
Cutting problematic frequencies rather than boosting others.
What does EQ stand for in audio production?
The answer is B) Equalization. EQ stands for Equalization, which is the process of adjusting the balance between frequency components within an electronic signal. It allows audio engineers to boost or cut specific frequency ranges to achieve desired tonal characteristics.
Equalization is one of the most fundamental tools in audio production. The term "equalization" comes from the idea of making the frequency response "equal" or balanced. In practice, we often use EQ to intentionally create imbalances that serve musical purposes, such as enhancing vocals or reducing problematic frequencies.
Equalization (EQ): Adjusting frequency balance in audio signals
Frequency Response: How a system responds to different frequencies
Boost: Increasing amplitude of specific frequencies
• EQ adjusts frequency balance
• Can boost or cut frequencies
• Essential for mixing and mastering
• Remember: EQ = Equalization
• Use EQ to fix problems, not create them
• Confusing EQ with other audio processing
If an EQ boosts a signal from 1V to 1.414V at a specific frequency, what is the gain in dB? Use the formula G = 20×log₁₀(Aout/Ain). Show your work.
Using the EQ gain formula: \(G = 20 \log_{10}\left(\frac{A_{out}}{A_{in}}\right)\)
Given:
Step 1: Calculate the ratio
\(\frac{A_{out}}{A_{in}} = \frac{1.414}{1} = 1.414\)
Step 2: Apply the logarithm
\(\log_{10}(1.414) = 0.1505\)
Step 3: Calculate the gain
G = 20 × 0.1505 = 3.01 dB
Therefore, the gain is approximately +3.01 dB at that frequency.
This calculation shows the logarithmic nature of the decibel scale. A doubling of voltage corresponds to +6 dB, while a 1.414× increase (square root of 2) corresponds to +3 dB. This relationship is fundamental to understanding how much change is represented by different dB values in audio processing.
Decibel (dB): Logarithmic unit for measuring ratios
Logarithmic Scale: Scale where each step is a multiple of the previousAmplitude: Strength of the signal
• Use the formula G = 20×log₁₀(Aout/Ain)
• 3 dB ≈ 1.414× voltage change
• 6 dB = 2× voltage change
• Remember: 3 dB ≈ 1.414×
• 6 dB = 2×
• 10 dB = 3.16×
• Forgetting the 20 multiplier in the formula
• Using log₂ instead of log₁₀
• Confusing voltage with power ratios
An engineer is processing a vocal track and applies the following EQ settings: -3dB at 200Hz (cutting muddiness), +2dB at 1kHz (adding presence), and +4dB at 10kHz (adding air). What is the total gain applied if all bands are summed? Is this considered aggressive EQ?
Step 1: Sum the gains
Total gain = -3dB + 2dB + 4dB = +3dB
Step 2: Evaluate if it's aggressive
The total gain is +3dB, which is relatively moderate. However, the individual changes (-3dB, +2dB, +4dB) are quite significant, especially the +4dB boost at 10kHz, which is considered aggressive.
Aggressive EQ typically involves changes greater than ±3dB in individual bands.
Therefore, the total gain is +3dB, but the individual settings are moderately aggressive.
This problem illustrates the difference between total gain and individual band adjustments. While the net gain might seem modest, individual band changes can still be significant. In audio production, it's often the individual band adjustments that matter more than the total sum, as each frequency range contributes differently to the overall sound.
Aggressive EQ: Large changes (>±3dB) in individual bands
Subtractive EQ: Cutting frequencies rather than boosting
Frequency Band: Specific range of frequencies
• Aggressive = changes > ±3dB
• Consider individual bands, not just total
• Subtractive EQ often sounds more natural
• Cut before boosting
• Small changes can have big impact
• Listen in context of full mix
• Only considering total gain, not individual bands
• Overlooking the cumulative effect of multiple bands
• Not accounting for phase interactions
A recording engineer notices rumble in a vocal track below 80Hz. They apply a high-pass filter at 100Hz with a slope of 12dB/octave. If the original signal had 0dB at 50Hz, what would be the approximate level at 25Hz after the filter is applied? (Hint: Each octave below the cutoff reduces the signal by the filter slope)
Step 1: Determine how many octaves below the cutoff 25Hz is
From 100Hz to 50Hz = 1 octave
From 50Hz to 25Hz = 1 octave
Total: 2 octaves below 100Hz cutoff
Step 2: Calculate the attenuation
Attenuation = Slope × Octaves = 12dB/octave × 2 octaves = 24dB
Step 3: Calculate the final level
Original level at 25Hz: 0dB
After filtering: 0dB - 24dB = -24dB
Therefore, the signal at 25Hz would be approximately -24dB after the high-pass filter.
This demonstrates the effectiveness of high-pass filters in removing low-frequency rumble. The 12dB/octave slope means that for every octave you go below the cutoff frequency, the signal is reduced by 12dB. This is crucial for cleaning up recordings and preventing low-frequency buildup that can muddy the mix.
High-Pass Filter: Allows high frequencies, attenuates low frequencies
Filter Slope: Rate of attenuation per octave
Octave: Doubling/halving of frequency
• HPF removes frequencies below cutoff
• Attenuation increases with distance from cutoff
• 12dB/octave = 24dB reduction per 2 octaves
• Use HPF to remove rumble and wind noise
• Set cutoff just below fundamental frequencies
• 80-120Hz for vocals is common
• Setting HPF too high and losing bass fundamentals
• Forgetting that slope is per octave
• Not considering the phase effect of filters
Which of the following EQ curves is most appropriate for reducing harshness in vocals around 3kHz?
The answer is B) Narrow, sharp cut. When addressing harshness around 3kHz in vocals, a narrow, sharp cut (notch filter) is most appropriate. This targets the specific problematic frequency without affecting surrounding frequencies that contribute to vocal presence and clarity.
Wide cuts would remove too much presence, while boosts would make the harshness worse.
When addressing specific frequency problems, precision is key. A narrow Q (bandwidth) allows you to surgically remove problematic frequencies without affecting the musical content around them. This is particularly important in the presence region (2-5kHz) where vocals carry important intelligibility and character.
Q Factor: Bandwidth of an EQ band (narrow/wide)
Notch Filter: Very narrow cut at specific frequency
Presence Range: 2-5kHz where vocals are most intelligible
• Use narrow Q for surgical cuts
• Use wide Q for musical shaping
• Cut harshness, don't boost clarity
• Sweep to find exact problem frequency
• Use narrow Q for resonances
• Wider Q for tonal shaping
• Using wide cuts for specific problems
• Boosting instead of cutting harshness
• Over-cutting and losing presence
Q: What's the difference between subtractive and additive EQ?
A: Subtractive EQ involves cutting or reducing specific frequencies, while additive EQ involves boosting or increasing specific frequencies.
Subtractive EQ is generally preferred because:
Mathematically, both follow the same gain formula:
\( G(f) = 20 \log_{10}\left(\frac{A_{out}(f)}{A_{in}(f)}\right) \)
But subtractive EQ uses ratios < 1 (negative gain), while additive uses ratios > 1 (positive gain).
Q: How do I know if I'm using too much EQ?
A: Signs of over-EQ include:
As a rule of thumb, if you need more than ±3dB in a band, consider if the issue can be fixed at the source (microphone placement, instrument setup, etc.). The sum of all EQ changes shouldn't exceed ±6dB to maintain natural sound.