Online Equalizer — Free Audio EQ in Your Browser

An equalizer is the single most important tool in a mixer's signal chain. Every professional DJ uses one. Every mixing console has one. And now, a full 3-band EQ is available directly in your browser at djmixer.online/mixer/radio/ — no download, no account, no plugins.

This guide explains what an equalizer does, how the 3-band EQ on our Radio FX processor works, and exactly how to use it for DJ mixing and live audio processing.

What Is an Equalizer?

An equalizer (EQ) is a tool that adjusts the volume of specific frequency ranges within an audio signal. The human ear hears frequencies from roughly 20 Hz (deep sub-bass) up to 20,000 Hz (air and shimmer). An equalizer lets you boost or cut different parts of that range independently.

Why would you want to do that? Because different instruments and sounds occupy different frequency regions. The kick drum lives in the low end. Vocals live in the mids. Cymbals and hi-hats live in the highs. When you adjust EQ, you are shaping the balance of those elements without changing the overall volume of the track.

For DJ mixing, this matters enormously. Two tracks playing simultaneously will clash if their bass lines collide. EQ lets you remove the bass from one track while the other plays, preventing that clash. It is the foundation of professional DJ transitions.

How Our 3-Band EQ Works

The equalizer on the Radio FX processor divides the audio spectrum into three bands, each controlled by a rotary knob:

Each knob sweeps from fully cut (silence for that band) through center (unity — no change to the original signal) to fully boosted (maximum gain for that band). The center position is the neutral point. Starting from center and moving left cuts; moving right boosts.

This is the same architecture used in professional DJ mixers from Pioneer, Allen & Heath, and Rane. Three bands, three knobs. Simple to learn, deep to master.

Kill Switches Explained

Above each EQ band is a kill switch — a button that instantly silences that frequency band entirely when pressed. Kill switches are faster and more decisive than turning the knob all the way down.

A common technique is to kill the low end on the outgoing track during a transition, then un-kill it on the incoming track at the exact moment you want the bass to return. The audience feels the bass return as a physical impact — it is one of the most effective moments you can create in a DJ set.

Kill switches are also used for effects: briefly killing the highs creates a muffled, underwater sensation. Killing the mids isolates the rhythmic skeleton of the track. Experimenting with different combinations produces effects that would take much longer to achieve by turning knobs manually.

When to Boost vs. Cut Frequencies

A rule that applies across professional audio: cut first, boost second. Cutting frequencies is cleaner than boosting them. Boosting adds gain, which can introduce distortion and makes the mix louder — which can mask problems rather than solving them.

For DJ mixing specifically:

• Cut low on the incoming track before bringing it in — prevents bass clash during transitions
• Cut high on the outgoing track to reduce its presence while keeping the rhythmic foundation
• Cut mid on a track that has a clashing melodic element to create space for the other track's melody
• Boost high slightly on a track that sounds flat or buried — adds presence and air
• Boost low carefully only when a track needs more body, and only temporarily

The goal is always a mix that sounds good to the ear, not a specific technical configuration. Use your ears as the primary reference. The EQ knobs are tools to fix problems and create effects, not formulas to follow mechanically.

Using EQ for DJ Mixing: The Bass Swap

The bass swap is the most important DJ technique built on EQ. It is how professionals change tracks without the two bass lines colliding.

Here is the procedure:

1. Track A is playing fully. Track B is cued up and beatmatched.
2. Bring Track B into the mix — but with its low EQ fully cut. Only its mids and highs are audible.
3. Over 8 to 16 bars, gradually reduce Track A's low EQ while simultaneously bringing up Track B's low EQ.
4. At the moment Track B's bass reaches full, cut Track A's bass entirely — or use the kill switch.
5. Now only Track B's bass is playing. Continue fading the crossfader to complete the transition.

Done correctly, the audience never hears two bass lines at once. The mix feels continuous and clean. This is the professional technique, and the Radio FX EQ gives you all the controls needed to practice it on any audio stream.

For a deeper dive into transition techniques built around EQ, see the 7 DJ transition techniques guide, which covers the EQ swap alongside six other methods.

Per-Deck Filter on the Main Mixer

In addition to the 3-band EQ on the Radio FX processor, the main DJ mixer at djmixer.online provides a per-deck filter knob on each channel. This filter sweeps from high-pass (removes bass, keeps highs) through neutral to low-pass (removes highs, keeps bass).

The filter operates differently from the EQ: rather than boosting or cutting a specific band, it rolls off everything above or below a moving cutoff frequency. This creates a more dramatic, sweeping effect often heard in progressive house and techno transitions.

Use the per-deck filter for dramatic transitions and effects. Use the 3-band EQ on the Radio FX processor for surgical frequency management during mixing. Both tools complement each other and are accessible free in the browser.

Accessing the Online Equalizer

The full 3-band EQ with kill switches is built into the Radio FX processor. To use it:

1. Go to djmixer.online/mixer/radio/
2. Click any preset to load it, or start from scratch
3. Use the LOW, MID, and HIGH knobs to shape the frequency balance
4. Use the kill switch buttons above each band for instant muting
5. Combine with the 14 available audio effects for complete processing control

Before your session, use the TuneLab Spectrum Analyzer to visually inspect the frequency content of your audio. This helps you understand which bands need attention before you start adjusting the EQ. Pair it with the BPM guide to understand tempo alongside frequency management.