A spectrum analyser gives you a live picture of the frequencies in your audio. It will not mix for you, but it is a powerful second opinion. APU Software is a developer known for free tools, and a free spectrum analyser from them, or any reputable maker, can teach you a lot about balance. This guide shows how to read one and use it wisely.
Please confirm: features, formats and availability of any specific plugin can change. Check the developer's official page before downloading.
What a spectrum analyser shows
The horizontal axis is frequency, from deep bass on the left to air and sizzle on the right. The vertical axis is level. Peaks show where energy is concentrated. Watching this while you play a track reveals imbalances you might miss by ear alone.
Approximate frequency ranges
| Range | Name | What lives here |
|---|---|---|
| 20 to 60 Hz | Sub | Sub bass, kick weight |
| 60 to 250 Hz | Bass | Bass guitar body, kick punch |
| 250 to 500 Hz | Low mids | Warmth, but also mud |
| 500 Hz to 2 kHz | Mids | Vocals, guitars, snare body |
| 2 to 6 kHz | Upper mids | Presence, clarity, harshness |
| 6 to 20 kHz | Highs | Air, cymbals, sparkle |
Setting up your analyser
- Insert it on the master channel, or on the track you want to inspect, as the last plugin.
- Choose a slow averaging or hold setting so the display is readable.
- Use a slope of around 3 or 4.5 dB per octave if available. Music often looks tilted otherwise.
- Play the loudest section for a full loop.
Practical uses
Finding mud
A hump between 200 and 400 Hz often causes muddy mixes. Try a gentle EQ cut on guitars, keys or vocals in that region and watch the analyser as you listen.
Taming harshness
Sharp peaks between 2 and 5 kHz may sound piercing. A narrow dip or a dynamic EQ can calm them.
Checking kick and bass overlap
Solo just those two and observe where they compete. Sidechain compression or complementary EQ carves space for each.
Comparing to a reference
Load a professionally mixed track and compare the shapes, keeping loudness matched. Do not copy the curve exactly, but note major differences.
Do not mix with your eyes only
The analyser is a guide. Musical genres differ widely: a trap track will show huge low end, while an acoustic song will not. Trust your ears and use the graph to confirm suspicions. Turn the plugin off occasionally and mix by listening.
Fix problems earlier in the chain
If the overall balance is wrong, the fix often lies in levels, not EQ. Review the gain staging guide, and learn how a compressor can rein in dynamic swings that distort the picture.
Where to find more tools
Once you have an analyser, pair it with a good EQ and metering suite. Our free VST collection lists many options. Always download from official developer pages and avoid cracked copies.
Common mistakes
- Chasing a flat line. Music is rarely flat.
- Ignoring the monitoring environment. Poor speakers or rooms mislead you more than any graph.
- Overcutting because a spike looks scary.
- Leaving heavy analysers running, which can add CPU load.
Key takeaways
- Spectrum analysers visualise frequency balance.
- Use them to confirm what you hear.
- Compare with references at matched loudness.
- Get plugins only from official sources.
Frequently asked questions
Do professionals use spectrum analysers?
Yes, as a support tool alongside careful listening.
What is a good analyser setting?
A moderate average time and a 4.5 dB per octave slope are common starting points.
Can an analyser fix my mix?
No, but it can point you toward problems.
Is the APU analyser still free?
Check the developer's site for current terms.
