EQ (equalization) adjusts the volume of specific frequency ranges in an audio signal, allowing you to boost or cut bass, midrange, and treble independently. Compression reduces the dynamic range of audio by making loud parts quieter and quiet parts louder, creating a more consistent and polished sound. In mixing, EQ is used to carve out space for each instrument, while compression controls dynamics so that every element sits at a stable level in the mix.
This guide is part of our mixing fundamentals series. If you are new to mixing, EQ and compression are the first two tools you should learn. Every professional mix relies on them, and understanding what they do puts you ahead of most bedroom producers who use them blindly.
What Is EQ and What Does It Do?
Equalization is volume control for specific frequency ranges. Sound is made up of frequencies measured in Hertz (Hz). Low frequencies (20-250Hz) are bass. Mid frequencies (250Hz-4kHz) are where most instruments and vocals live. High frequencies (4kHz-20kHz) are treble, which includes brightness, air, and detail.
An EQ plugin lets you select a specific frequency range and turn it up (boost) or turn it down (cut). If a vocal sounds dull, you might boost the 3-5kHz range to add presence. If a guitar sounds boomy, you might cut the 200-300Hz range to remove excess low-mid energy. EQ is the primary tool for making instruments sound clear and distinct from each other.
Types of EQ Bands
- High-pass filter: Removes all frequencies below a set point. Used to clean up rumble and low-end clutter from non-bass instruments.
- Low-pass filter: Removes all frequencies above a set point. Used to tame harshness or remove high-frequency noise.
- Bell (parametric): Boosts or cuts a specific frequency range with adjustable width (Q). The most versatile EQ shape for targeted adjustments.
- Shelf: Boosts or cuts all frequencies above (high shelf) or below (low shelf) a set point. Used for broad tonal changes like adding overall brightness or warmth.
Practical EQ Starting Points
When EQing a vocal, start by high-pass filtering at 80-100Hz to remove rumble, then listen for muddiness in the 200-400Hz range and cut gently if needed. Add presence by boosting 2-5kHz slightly. For guitars, high-pass at 80-100Hz, cut any boxiness around 250-400Hz, and boost 1-3kHz for bite. The goal is to make each instrument sound clear on its own and even clearer when everything plays together.
Beginner Rule of Thumb
Cut to fix problems, boost to enhance character. Cutting narrow (tight Q) removes specific issues without affecting surrounding frequencies. Boosting wide (loose Q) adds character without creating resonant peaks. When in doubt, cut rather than boost.
What Is Compression and What Does It Do?
Compression is an automatic volume control. It detects when the signal gets louder than a set level (the threshold) and turns it down by a specified amount (the ratio). The result is a smaller difference between the loudest and quietest parts of the audio, which makes the sound more consistent and easier to place in a mix.
Without compression, a singer's voice might swing between barely audible whispers and piercing loud notes. The listener has to constantly adjust their perception, and the vocal fights with other instruments at different moments. Compression evens out those dynamics so the vocal sits at a stable level throughout the song.
The Five Key Compression Parameters
- Threshold: The level at which compression begins. Signal below the threshold passes through unchanged. Signal above it gets compressed.
- Ratio: How much the signal is reduced once it crosses the threshold. A 4:1 ratio means that for every 4 dB the signal goes above the threshold, only 1 dB comes out.
- Attack: How quickly the compressor reacts after the signal crosses the threshold. Fast attack catches transients immediately. Slow attack lets the initial punch through before compressing.
- Release: How quickly the compressor stops compressing after the signal drops below the threshold. Too fast creates a pumping effect. Too slow keeps the signal compressed too long.
- Makeup gain: After compression reduces the peaks, makeup gain brings the overall level back up. This is what makes the quiet parts sound louder relative to the peaks.
Practical Compression Settings for Common Sources
Here are safe starting points for the sources you will compress most often. These are guidelines, not rules. Always adjust by ear based on the specific recording.
- Lead vocal: Ratio 3:1 to 4:1, medium attack (10-30ms), medium release (50-100ms), aim for 3-6 dB of gain reduction on peaks
- Drums (bus): Ratio 2:1 to 4:1, slow attack (20-40ms) to preserve transients, fast release (50-80ms), 2-4 dB of gain reduction
- Bass guitar: Ratio 3:1 to 6:1, fast attack (5-15ms), medium release (80-150ms), 4-8 dB of gain reduction for a consistent foundation
- Acoustic guitar: Ratio 2:1 to 3:1, medium attack (15-25ms), medium release (80-120ms), 2-4 dB of gain reduction
For a more detailed vocal processing chain including the order of EQ, compression, and effects, see our vocal mixing chain guide.
Should EQ Come Before or After Compression?
This is one of the most asked questions in mixing, and the answer depends on what you are trying to achieve. EQ before compression shapes the tone first, which changes what the compressor reacts to. If you cut muddy low-mids before the compressor, the compressor will not be triggered by that unwanted energy and will compress more musically. EQ after compression shapes the final tone after dynamics are controlled, giving you precise tonal sculpting without affecting the compressor's behavior.
Many professionals use both: a corrective EQ before the compressor to remove problem frequencies, then a tonal EQ after the compressor to add character and presence. This is a common approach for vocals and is covered in depth in our guide on mixing low end, where the order of EQ and compression is critical for bass and kick drum clarity.
Common Beginner Mistakes with EQ and Compression
The most common EQ mistake is boosting everything. If you boost the bass on the kick, the low-mids on the guitar, the mids on the vocal, and the treble on the cymbals, you have essentially turned everything up equally and gained nothing. Use cuts to create space, and boost sparingly for character. The second most common mistake is using too narrow a Q for boosts, which creates unnatural resonant peaks that sound harsh and digital.
For compression, the biggest mistake is watching the gain reduction meter instead of listening. A compressor reducing 10 dB of gain might sound fantastic on one source and terrible on another. Trust your ears over the numbers. The second mistake is using identical settings on every track. Each source has different dynamics and requires different compression parameters.
If learning these tools feels overwhelming, modern AI mixing platforms can apply intelligent EQ and compression to your tracks automatically, giving you a professional starting point to learn from and refine.
About Genesis Mix Lab
Genesis Mix Lab is a browser-based AI mixing and mastering platform for music producers. It offers AI-powered multitrack mixing and mastering in a single platform, with features including reference track matching, genre-aware processing, and real-time Mix Notes. Pricing starts at $0/month (free tier) with Pro at $19.99/month.
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