The Compression Troubleshooter
Step zero: does this source actually need compression? If the dynamics don't bother you, no compressor is the best compressor.
Understanding Compression Problems
What the troubleshooter can't show you
Why Attack and Release Cause Most Problems
Most compression problems trace back to two settings: attack time and release time. Not ratio, not threshold, not the compressor plugin. Attack and release don't just control how much compression happens - they control what gets compressed. A fast attack catches transients and reduces punch. A slow attack lets them through. A fast release recovers before the next hit. A slow release holds on and shapes the sustain. Getting these wrong changes the fundamental character of the sound. The Compression Visualiser makes this much easier to understand when you can see it happening in real time.
The Cumulative Compression Trap
The sneakiest compression problem isn't any single compressor - it's what happens when you stack them. Your kick insert does 4dB of gain reduction. The drum bus adds 3dB. The mix bus adds 2dB. Each sounds fine in isolation, but that kick is now being compressed three times. Here's the part most people don't realise: compression ratios multiply in series. A 4:1 on the insert into a 3:1 on the bus creates an effective 12:1 - that's approaching limiting.
Think of compression as a budget. Every dB of gain reduction you spend at one stage is a dB you can't spend elsewhere without flattening the mix. The Compressor Calculator can help you set conservative starting points at each stage. And always dial in your compression on the loudest section of the song - settings tuned to the verse will over-compress when the energy picks up.
When Not to Compress
Distorted electric guitars are already heavily compressed by the amp's distortion circuit - adding more for dynamic control usually makes them sound smaller, not better. Programmed drums with identical velocity hits have no dynamic variation for a compressor to shape. Synth pads with consistent levels often lose their movement when compressed. Sometimes saturation can do the job of gentle compression while adding warmth instead of just squashing.
If the problem you're hearing is actually an EQ issue masquerading as compression, the EQ Frequency Chart can help you identify what's really going on. Boosting a problem frequency before the compressor makes the compressor react to that boost - so the fix might be EQ, not compression. The question to ask before reaching for a compressor isn't "what settings should I use?" It's "what specific problem am I trying to solve?"
Developing Your Ear for Compression
Exaggerate first, then dial back. Set extreme settings so the compression is obvious and ugly. Listen to what that extreme is doing. Then gradually back off until it sounds musical. You've now heard the full range of what that compressor does on that source.
Always level-match before comparing. Makeup gain makes the compressed version louder, and louder always sounds better regardless of what the compression is actually doing. Match the loudness, then toggle bypass. If the difference isn't subtle, you're probably over-compressing.
Listen in context, not in solo. A compressor that sounds perfect on a soloed vocal might be destroying its ability to sit in the mix. The goal is never "does this track sound good alone?" - it's "does this track serve the song?"
Compression and the Bigger Picture
Want to keep exploring? Ask Dan anything about compression, EQ, or mixing - it's an AI tutor trained on 20 years of mixing experience. For more hands-on tools, check out the Learning Hub including the Compressor Calculator and Loudness Lookup.
Compression Glossary
Key compression terms used throughout this tool, explained for beginners.
- Attack Time
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. This is the single most impactful compression control on drums.
- Release Time
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 over successive hits. The release should reset before the next transient arrives.
- Ratio
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. Ratios multiply in series - a 4:1 into a 3:1 creates an effective 12:1.
- Threshold
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. Lower the threshold to compress more of the signal, raise it to compress only the loudest peaks.
- Knee
Controls how gradually the compressor transitions from no compression to full compression at the threshold. A hard knee engages abruptly - good for drums and aggressive compression. A soft knee eases in gradually - good for vocals and transparent levelling.
- Makeup Gain
Volume added after compression to bring the overall level back up. Critical to level-match when A/B comparing compressed and uncompressed signals, because louder always sounds better to our ears regardless of whether the compression is actually helping.
- Opto (Optical)
Compressor that uses a light element and photoresistor to control gain. Naturally smooth, slow behaviour with program-dependent attack and release. The classic LA-2A is an opto design. Best for transparent levelling on vocals and bass.
- VCA (Voltage Controlled Amplifier)
Fast, precise compressor that responds accurately to the control signal. Clean and transparent - does not add significant colour. The SSL bus compressor and dbx 160 are VCA designs. Best for bus compression and when you want control without character.
- FET (Field Effect Transistor)
Fast-reacting compressor that adds harmonic brightness and forward energy. The classic 1176 is a FET design. The all-buttons-in mode is a popular creative effect on drums and vocals. Best when you want the compressor to add character alongside control.
- Variable-Mu (Vari-Mu)
Tube-based compressor with naturally slow, gentle behaviour. Compression ratio increases as the signal gets louder. The Fairchild 670 is the legendary example. Best for mix bus glue and warm, musical levelling where transparency is not the goal.
- Parallel Compression
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.
- Sidechain
The detection circuit that tells the compressor when to engage. By default it listens to the input signal, but you can feed it an external source (sidechain input) or filter it. A sidechain high-pass filter at 80-150Hz stops bass-heavy content from driving excessive gain reduction on bus compressors.
- Gain Reduction
The amount the compressor is turning the signal down, measured in dB. Visible on the gain reduction meter. A useful budget framework: individual tracks 3-6dB, drum bus 2-4dB, mix bus 1-2dB. Remember that gain reduction from multiple stages adds up cumulatively.
- RMS vs Peak Detection
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.
Frequently Asked Questions
Common questions about compression problems and how to fix them.
Why does my compressor kill the punch on drums?
Your attack time is faster than the drum transient. Below 10ms on most drums, the compressor clamps down on the initial hit before it reaches the listener. That transient is what creates the perception of punch.
Slow your attack to 15-30ms. Sweep it from fast to slow and listen for the moment the snap or crack reappears. That's the transient getting through. This applies to kick, snare, and toms - each has a slightly different sweet spot, but all need the attack to let the front end through.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
Why is my compressor pumping?
The release time is too slow for the tempo. The compressor engages on each hit but doesn't recover before the next one arrives. Gain reduction builds up, then suddenly releases during a gap - creating that audible breathing or pumping effect.
Watch the gain reduction meter: each hit should cause it to dip and return to near zero before the next hit. If it's building up over several hits, shorten the release. On a bus compressor, also check whether the kick drum is driving the compression - a sidechain high-pass filter at 80-150Hz (start at 80Hz, go higher for bass-heavy genres) stops the low end from triggering excessive gain reduction.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
How do I stop compression from making things sound dull?
High-frequency detail lives in the transients, and a fast attack removes them. When the compressor catches the front end of each note or hit, it's squashing the part of the signal that contains the most brightness and clarity.
Slow your attack to 10-30ms to let the transient detail through. If you're running multiple compressors in series, the cumulative transient loss across the chain can strip brightness even when each stage looks moderate. Check each stage independently to find which one is doing the most damage.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
How much compression is too much?
It depends on the goal, but most problems come from cumulative compression across multiple stages. 4-6dB on a single track insert is usually fine. But if that track also feeds a bus doing 3dB and a mix bus doing 2dB, the total effect is far more aggressive than any individual meter suggests. Remember: compression ratios multiply in series - a 4:1 into a 3:1 creates an effective 12:1.
As a guideline: individual tracks 3-6dB, drum bus 2-4dB, mix bus 1-2dB. If the mix sounds flat or lifeless, bypass compressors one stage at a time - starting from the mix bus and working backwards - to find where the life is being lost.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
Why does my mix sound flat even with moderate compression settings?
Cumulative compression is almost always the cause. Each compressor in the chain looks reasonable in isolation, but the combined gain reduction across inserts, buses, and the mix bus strips out the dynamic contrast that makes a mix feel alive. And ratios multiply: a 4:1 on the insert into a 3:1 on the bus = effective 12:1. That's approaching limiting.
Try this: bypass every compressor in the session and listen to the raw mix. It should sound dynamic, punchy, and alive (even if it's messy). Then add compressors back one stage at a time. When the mix starts to flatten, you've found the stage that needs to be backed off. Also: always dial in compression on the loudest section (usually the chorus) - settings tuned to the verse will over-compress when the energy picks up.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
Should I compress distorted electric guitar?
Rarely for dynamic control, but sometimes for tonal colour. A distorted guitar is already heavily compressed by the amp's distortion circuit. Adding more compression for level control usually makes it sound smaller and flatter. However, compression for tonal colour (an 1176 or Distressor for character) is a valid creative choice used by many professionals.
Exception: palm-muted sections have slightly different dynamics from open chords, so light compression can help even them out. For clean or lightly driven guitars: 2:1-4:1 ratio, 10-30ms attack, 3-5dB gain reduction maximum. For heavy guitars, volume automation or clip gain is usually more effective than compression.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
What compressor type should I use on vocals?
It depends on what you're trying to achieve. An opto compressor (LA-2A style) is great for smooth, invisible levelling. A FET compressor (1176 style) adds harmonic brightness and forward energy that helps vocals cut. A VCA is transparent and precise. A Vari-Mu (Fairchild style) adds rich, warm vintage colouration.
The standard professional approach for many vocals is a series chain: a common order is FET first (2-3dB, catches peaks and adds character), opto second (2-3dB, gentle levelling). Some engineers reverse this - try both and use whichever sounds better on the vocal. Each stage doing less work always sounds more natural than one compressor working hard.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
How do I A/B compression properly?
Level-match before you compare. This is the most important step and the one most people skip. Compression reduces peaks, and makeup gain brings the overall level back up. If you don't match the loudness, you're comparing a louder signal to a quieter one, and louder always sounds better - regardless of what the compressor is doing.
Use a VU meter or LUFS meter to match the compressed and bypassed signals to the same loudness. Then toggle bypass during a dynamic section (quiet verse to loud chorus). The difference should be subtle: the compressed version more consistent, the uncompressed version more dynamic. If you can't hear any difference, either the compressor isn't doing enough or you haven't level-matched properly.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
What's the difference between parallel compression and series compression?
Series compression means multiple compressors in sequence on the same signal. The output of the first feeds the input of the second. Each stage does a small amount of work, which sounds more natural than one compressor doing everything. The classic vocal chain (FET then opto) is series compression.
Parallel compression means blending a heavily compressed copy with the original dry signal. You send the track to an aux bus, crush it with aggressive settings, then mix that bus back in underneath. You get the energy and density of heavy compression without losing the dynamics of the original. It's especially effective on drums where you want power without flatness.
For a step-by-step diagnosis, try the Compression Troubleshooter above.
Why does my compressor distort on bass?
Your release time is faster than the bass note's wavelength. When the release is too fast on low-frequency material, the compressor tries to follow individual wave cycles instead of the overall note envelope. This literally reshapes the waveform, creating harmonic distortion.
The fix is straightforward: slow your release to 100ms or longer. Play a sustained low bass note and sweep the release from fast to slow. You'll hear a clear point where the distortion disappears - that's the compressor switching from wave-cycle tracking to envelope tracking. Stay above that threshold. The lower the note, the slower the release needs to be.
For a step-by-step diagnosis, try the Compression Troubleshooter above.