How to Set 31 Band Equalizer | Flat Start, Small Moves

Set a 31-band EQ by starting flat at 0 dB, then cutting or boosting only the specific frequencies that need correction.

Most EQ problems are made worse by too many hands on too many sliders. A 31-band equalizer gives you surgical control over the full audio spectrum, and the correct setup starts with restraint. Professional manuals from Peavey and ART agree on the same method: flat start, bypass comparison, and small, targeted adjustments.

Understanding the 31-Band Layout

A 31-band graphic EQ divides the audible range into 31 fixed frequency bands using ISO 1/3-octave spacing, from 20 Hz to 20 kHz. Each fader controls a narrow slice roughly a third of an octave wide, which lets you treat specific problem areas without disturbing the frequencies around them.

The standard band centers are: 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1k, 1.25k, 1.6k, 2k, 2.5k, 3.15k, 4k, 5k, 6.3k, 8k, 10k, 12.5k, 16k, and 20 kHz.

Low bands (20–250 Hz) control bass and sub-bass; mids (315 Hz–2 kHz) shape body and presence; high bands (2.5–20 kHz) affect air, brightness, and sibilance.

The Official Setup Procedure

Peavey’s EQ 31FX and ART’s HD series manuals both describe the same starting sequence.

1. Set all sliders to the center detent (0 dB). The detent is the tactile notch in the middle of each fader’s travel.
2. Set input and output level controls to their center positions. Unity gain prevents clipping before the EQ stage.
3. Engage the bypass switch. This routes the dry, uneffected signal to the output so you hear the unprocessed source.
4. Play program audio at a normal operating level, and listen carefully to the unprocessed sound.
5. Disengage bypass and begin equalizing. Make one or two small adjustments at a time, then re-engage bypass to compare against the original.

ART’s manual recommends working on a ±6 dB range first, switching to ±12 dB only if you need more travel. Peavey’s EQ 31FX and ART’s HD131/HD231, plus similar racks like the Nady GEQ 131 and Yamaha GQ1031BII, all follow this same workflow.

How to Actually Adjust the Sound

Start with a flat EQ, then make small cuts or boosts only in the frequency regions that are actually causing problems. A typical correction might involve a 3 dB cut at 250 Hz to reduce boxiness, or a 3 dB boost at 10 kHz to add air. Resist the urge to lift the entire low end or add a smiley-face curve; boosting everything reduces dynamic range and can make the system clip.

The bypass function is your best tool for dialing in the sound. Switch it on and off to hear what the EQ is actually changing rather than relying on memory of the original signal. If the clip or overload LED lights up after your adjustments, lower the output level or trim the input gain — never rely on heavy boost to compensate for a weak system.

A 31-band EQ adjusts tone, but it cannot fix room acoustics, microphone placement, or bad source audio. It shapes the signal that’s already there; it cannot manufacture quality that isn’t in the recording.

Common Mistakes to Avoid

• Boosting everything — the most common error; it adds noise, reduces headroom, and rarely sounds better.
• Making large EQ moves — a 6–9 dB adjustment across several bands is a sign you’re fixing the wrong problem. Small moves sound more natural.
• Skipping bypass comparisons — without A/B listening, you can’t hear the true effect of your changes.
• Not starting from flat — if the unit was left with previous settings, you don’t know what you’re actually hearing.

When you’re ready to pick the best unit for your use case, check out our tested roundup of the best 31-band EQ units covering both budget and pro rack options.