System Online
Free Tool
Module Compression Visualiser
Output Real-Time
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// Free Tool — Compression

Compression Visualiser

Adjust threshold, ratio, attack, and release and watch compression shape the waveform in real time — see exactly what each control does to your signal.

Amplitude Over Time
Original
Compressed
Threshold
GR
Gain Reduction Over Time
Compressor Settings
Threshold -12 dB
Ratio 4:1
Attack 10 ms
Release 100 ms
Peak Gain Reduction 0.0 dB
What's Happening
Adjust the controls above to see how compression affects the waveform.
No Compression

What Your Compressor Is Actually Doing

See the settings, understand the sound

The Signal Chain in Four Controls

Your audio comes in, the compressor watches its level, and the moment it crosses the threshold - the red dashed line above - the compressor turns it down. How much depends on the ratio. How fast it reacts is the attack. How fast it lets go is the release. Four controls, one job: reduce the level of audio that's too loud. The reason it gets confusing is that those four controls interact in ways that are hard to hear but easy to see. Lower the threshold to -20dB, push the ratio to 4:1, and watch the teal waveform pull away from the amber. That gap is gain reduction.

Attack Is the Control That Matters Most

Attack sets how quickly the compressor clamps down after the signal crosses the threshold. Set it to 0.5ms with Zoom on - the teal line catches the transient almost instantly. Now try 30ms and watch the transient spike through before compression kicks in. That spike is punch. Fast attack kills it, slow attack preserves it. This is the single biggest decision you make on drums - a snare that slaps versus a snare that thuds comes down to a few milliseconds of attack time.

Release Controls the Recovery

Watch the Gain Reduction graph below the waveform as you adjust release. The amber trace shows exactly how fast the compressor recovers. If the release is too slow, gain reduction builds up and doesn't reset before the next hit - that's pumping. If it's too fast on bass, you get harmonic distortion. The sweet spot is where the GR trace returns to near zero just before the next transient arrives.

Killing Transients

Toggle Zoom on and set the attack to 0.5ms. See how the compressed waveform meets the original almost immediately? The compressor is catching the initial snap before it reaches the listener. Slow the attack to 25ms and watch the transient punch through. If your drums sound lifeless after compression, your attack is almost certainly too fast. The Compression Troubleshooter walks you through diagnosing this in a real mix.

Pumping and Over-Compression

Set a low threshold (-25dB), moderate ratio (4:1), and a fast release (20ms). Watch the GR graph - the amber trace dips and snaps back aggressively on every transient. That rapid recovery is audible as a breathing, pumping effect. Now push the threshold to -30dB with a 10:1 ratio. The compressed waveform barely moves - the dynamics are gone. If the Peak GR meter shows more than 10dB, you're in aggressive territory. A healthy range is 3-6dB on individual tracks, 2-4dB on a bus, and 1-2dB on the mix bus.

Compression and the Bigger Picture

Corrective EQ before compression, tonal EQ after. The compressor reacts to whatever you feed it - remove problem frequencies first, compress a clean signal, then shape tone afterwards. The EQ Frequency Chart maps 21 instruments across the frequency spectrum to help you make that call.

Need starting-point settings for a specific instrument? The Compressor Calculator gives you research-backed recommendations for over 20 sources. Ask Dan anything about compression, EQ, or mixing - it's an AI tutor trained on 20 years of mixing experience. For the full collection, visit the Learning Hub.

Compression Glossary

Key terms from the visualiser above, explained for beginners.

The level at which the compressor starts working. Signal below the threshold passes through unchanged. Signal above it gets compressed by the amount set by the ratio. In the visualiser above, this is the red dashed line - everything above it gets processed, everything below is untouched.

How much the signal is reduced once it crosses the threshold. At 4:1, a signal 8dB over threshold is reduced to 2dB over. Higher ratios mean more aggressive compression. Above 10:1 approaches limiting. Ratios multiply in series - a 4:1 into a 3:1 creates an effective ratio of about 12:1.

How quickly the compressor starts reducing gain after the signal crosses the threshold. Fast attack (under 5ms) catches transients and reduces punch. Slow attack (15-30ms) lets transients through, preserving snap and impact. In the visualiser, toggle Zoom on to see how attack time shapes the transient.

How quickly the compressor stops reducing gain after the signal drops below the threshold. Too fast on bass causes harmonic distortion. Too slow causes pumping as gain reduction builds up. The amber trace in the Gain Reduction graph shows exactly how fast the compressor is recovering.

Volume added after compression to bring the overall level back up. Compression reduces peaks, which drops the average level. Makeup gain compensates. Critical for A/B comparison - always level-match before toggling bypass, because louder always sounds better to our ears regardless of whether the compression is actually helping.

The amount the compressor is turning the signal down, measured in dB. Shown on the GR meter and as the amber trace in the Gain Reduction graph. A useful budget: 3-6dB on individual tracks, 2-4dB on a bus, 1-2dB on the mix bus. Gain reduction from multiple compression stages adds up cumulatively.

Controls how gradually the compressor transitions from no compression to full compression at the threshold. A hard knee engages abruptly - the compressor is off, then on. Good for drums and aggressive compression. A soft knee eases in gradually over a few dB around the threshold - good for vocals and transparent levelling. Not shown in this simplified visualiser but present on all real compressors.

The detection circuit that tells the compressor when to engage. By default it listens to the input signal, but you can filter it (high-pass at 80-150Hz to stop bass from driving excessive GR on buses) or feed it an external source (kick drum sidechaining a bass guitar so the bass ducks on every kick hit).

Two ways a compressor measures the input signal. Peak detection responds to absolute waveform peaks - faster, catches transients. RMS detection responds to average energy over time - slower, more musical, closer to how we perceive loudness. Most modern compressors let you choose or blend between the two.

Blending a heavily compressed copy of the signal with the uncompressed original. You get the energy and density of aggressive compression without losing the dynamics of the dry signal. Especially effective on drums. Set up via an aux send or a wet/dry mix knob on the compressor plugin.

A compressor mode where the attack and release times automatically adapt to the input signal. Opto compressors like the LA-2A are naturally program-dependent - the light element responds differently to different material. Simplifies setup but gives less precise control than setting attack and release manually.

Compression with a very high ratio, typically 10:1 or higher, often infinity:1. Prevents the signal from exceeding the threshold rather than gently reducing it. Used on the mix bus during mastering to control final output level and prevent clipping. In the visualiser above, push the ratio to 20:1 to see limiting behaviour - the compressed waveform essentially hits a ceiling.

// FAQ

FAQ

What does a compressor do to audio?
A compressor reduces the volume of audio that exceeds a threshold you set. The amount of reduction is controlled by the ratio - at 4:1, a signal 8dB over threshold becomes 2dB over. This evens out the dynamic range between the loudest and quietest parts. The result is a more consistent, controlled signal that sits better in a mix.
What is gain reduction in compression?
Gain reduction is the amount in dB that the compressor is turning the signal down at any given moment. It is shown on the gain reduction meter and fluctuates as the signal level changes. A useful budget: 3-6dB on individual tracks, 2-4dB on bus compression, 1-2dB on the mix bus. More than 10dB on a single stage is heavy compression territory.
What is the difference between threshold and ratio?
Threshold sets where compression begins - the level the signal must exceed before the compressor engages. Ratio sets how aggressively signal above the threshold is reduced. Together they determine how much compression happens: a low threshold catches more of the signal, and a higher ratio compresses it harder. Both controls interact, so adjusting one often means re-evaluating the other.
What does attack time do on a compressor?
Attack time controls how quickly the compressor clamps down after the signal crosses the threshold. A fast attack under 5ms catches transients and reduces punch. A slow attack of 15-30ms lets the initial transient punch through before compression engages. This is the single most important control on drums - it determines whether a snare snaps or thuds.
What does release time do on a compressor?
Release time controls how quickly the compressor stops reducing gain after the signal drops below the threshold. Too fast a release on bass causes harmonic distortion. Too slow causes pumping as gain reduction builds up over successive hits and does not reset in time. The ideal release lets the compressor recover just before the next transient arrives.
How do I set attack and release on a compressor?
Start with a medium attack around 10-15ms and medium release around 100-150ms. Slow the attack until you can hear or see the transient punch through, then stop. For release, watch the gain reduction meter and make sure it resets to near zero before the next hit arrives. If gain reduction builds up over time, shorten the release. If it snaps back too aggressively, lengthen it.
What compressor ratio should I use?
It depends on the source material. Use 2:1 to 3:1 for gentle levelling on vocals, bass, and mix bus. Use 4:1 to 6:1 for moderate control on drums and guitars. Use 8:1 to 10:1 for aggressive compression. Anything above 10:1 approaches limiting. Remember that ratios multiply in series, so a 4:1 compressor feeding a 3:1 creates an effective ratio of about 12:1.
How do I set the threshold on a compressor?
Lower the threshold until the gain reduction meter starts moving on the loudest parts of the signal. For individual tracks, aim for 3-6dB of peak gain reduction. For bus compression, 2-4dB. For mix bus, 1-2dB. Always set the threshold while listening to the loudest section of the song so you do not over-compress during quieter parts.
What does compressor ratio actually mean?
Ratio describes how much signal above the threshold is reduced. At 4:1, for every 4dB the signal exceeds the threshold, only 1dB comes through. So 8dB over becomes 2dB over, and 16dB over becomes 4dB over. At 1:1 there is no compression. At infinity to one, no signal exceeds the threshold at all - that is a limiter.
Why does my compressor kill the punch on drums?
Your attack time is too fast. Below about 10ms on most drums, the compressor catches the transient before it reaches the listener, removing the snap and impact. Slow the attack to 15-30ms and the punch reappears because the transient passes through before compression engages. This is the most common compression mistake on drums.
What is compression pumping and how do I fix it?
Pumping happens when the release time is too slow for the tempo of the material. The compressor does not recover between hits, so gain reduction accumulates and then suddenly releases during a gap, creating an audible breathing or surging effect. Fix it by shortening the release time until the gain reduction resets before each new transient arrives.
What is the difference between a compressor and a limiter?
A limiter is a compressor with a very high ratio, typically 10:1 or higher, often infinity to one. It prevents the signal from exceeding the threshold rather than just gently reducing it. Limiters are used on the mix bus during mastering to control final output level and prevent clipping. In practice, many compressors become limiters when you push the ratio above 10:1.
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