Reading the spectrum.

Reading the screen

A spectrum analyzer redraws what you hear as a picture of frequencies. Left to right runs low to high — 20 Hz to 20 kHz on a logarithmic scale, with bass on the left and treble on the right. Up and down shows amplitude in decibels: the taller the peak, the more energy at that spot.

The image comes from an FFT, a math routine that breaks the signal into its frequency parts. Larger FFT sizes resolve finer detail but respond more slowly; for mastering, somewhere around 4096 or more keeps resonances visible instead of smearing them together.

Learn the neighborhoods

Almost every problem has a neighborhood it lives in. Once you can picture where each region sits, the graph stops being noise and becomes a map.

• 20–60 Hz — sub-bass; felt more than heard, and where rumble collects
• 60–250 Hz — bass and warmth; too much around 120–150 Hz turns boomy
• 250–500 Hz — low-mid body; crowding near 500 Hz sounds boxy and starts masking
• 500–2 kHz — the midrange where vocals live; push it too hard and it turns nasal
• 2–4 kHz — upper-mids carrying attack and consonants; excess causes fatigue
• 4–6 kHz — presence and sibilance; de-essers aim here
• 6–20 kHz — air and sparkle; a gentle rolloff sounds natural, too much turns brittle

The shape of a balanced master

Pink noise is a handy reference: it carries equal energy in every octave, so a balanced mix approximates its gently falling line from bass to treble. Aim for a smooth curve without extreme spikes or valleys, with energy spread across the spectrum — keeping in mind that genre changes the expectation. Electronic music leans on low end; acoustic jazz sits in the mids.

Resonances and how to deal with them

Resonances show up as narrow spikes in the upper-mids, around 2–8 kHz, or as wide bumps in the lows and low-mids around 100–500 Hz. They're the notes that feel harsh or stuck out no matter the arrangement. Peak-hold mode is your friend here — it freezes the maximums so they stay visible while you audition the fix.

Find the exact frequency by sweeping a tight boost until the spot screams, then cut it with a narrow Q, typically 2–6 dB. The graph points, but the ear confirms — never correct something you haven't heard.

Compare live, not in freeze-frames

When A/B-ing against a reference, watch both curves live during the same kind of moment — verse against verse, chorus against chorus. A frozen screenshot captures a single instant and invites you to chase a ghost. What actually matters is the overall slope, the low-to-high balance, and how dense the mids sit.

Treat the reference as context, not a stencil. No two arrangements sound the same, so chasing an exact copy of someone else's curve rarely works.

Keep the ears in charge

There's no correct spectrum. Two excellent songs in the same genre can trace very different curves. Use the analyzer to verify instincts and point at cuts, but make the final call by listening.