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What the EQ Actually Does: The Three Moves That Fix Most Problems
High pass, cut before boost, and the small number of frequency areas that account for nearly every problem you will meet on a small stage.
~8 min read · Updated August 2026 · By the Stage Supply team
In this guide:The bands · High-pass first · Cut before boost · Finding it · Common fixes · Picks · FAQ
EQ is where beginners do the most damage, because the controls invite you to turn things up. Almost all useful live EQ is subtraction: finding the thing that is wrong and taking it out, rather than adding what you think is missing.
You do not need to memorise a frequency chart. Five areas cover nearly everything you will meet on a small stage.
What the knobs actually control
A channel strip gives you between two and four bands, plus a high-pass filter. On a digital desk each band is usually parametric, meaning you choose the frequency as well as the amount, and often the width.
| Control | Range | What lives there | Typical live move |
|---|---|---|---|
| High-pass filter | 20 to 200 Hz | Stage rumble, handling noise, plosives, air handling | On, for everything except kick and bass |
| Low | 60 to 250 Hz | Weight and body; also boom and mud | Cut on most channels, boost sparingly |
| Low mid | 250 to 800 Hz | Boxiness, honk, the sound of a small room | The most useful cut on the desk |
| High mid | 1 to 5 kHz | Intelligibility, attack, harshness | Small moves only, this is where ears are most sensitive |
| High | 5 kHz up | Air, sizzle, cymbals, sibilance | Gentle boost for air, cut for harsh |
Start with the high-pass filter
The high-pass filter is the single most valuable control on a live desk and the one beginners ignore. It removes everything below the frequency you set, and almost nothing on a stage has useful content below 100 Hz except the kick drum, the bass and a keyboard patch.
Everything else is picking up stage rumble, foot noise, air conditioning and plosives, and all of that is eating headroom in the mix and in the amplifiers. Engaging the high-pass on every vocal and every other microphone will clean up a muddy mix faster than any other single action.
A starting point, not a rule
Vocals around 100 Hz, acoustic guitar around 100 Hz, overheads around 250 Hz, keys around 80 Hz, and off for kick and bass. Then use your ears: sweep upwards until the source thins, then come back a little.
Why cutting beats boosting
Boosting adds level, which eats headroom and pushes you closer to feedback. Cutting removes a problem and leaves headroom behind. Two channels that both have their low mids cut sound clearer together than two channels that both have their highs boosted, and the second pair is much closer to howling.
The professional habit is: if something sounds dull, find what is making it dull and remove that, rather than adding treble. Most of the time the answer is a cut somewhere between 250 and 500 Hz.
How to find the offending frequency
The technique is the same on every desk with a parametric band.
- Set a narrow width and a large boost, maybe 10 dB, on the band you suspect.
- Sweep the frequency slowly while the source is playing. The problem will leap out and sound obviously worse.
- Stop there, then turn the boost into a cut of a few dB.
- Widen the band slightly until the cut sounds natural rather than surgical.
It takes thirty seconds and it is far more effective than guessing. Do it during soundcheck, not during the show.
Five problems and the move that fixes them
- Muddy, congested mix: cut 250 to 400 Hz on several channels, not one. Mud is cumulative.
- Boomy vocal: the singer is working the microphone very close. High-pass and a small low cut, and do not fight the proximity effect with a huge dip.
- Honky, nasal vocal: narrow cut somewhere between 500 Hz and 1 kHz.
- Harsh, fatiguing sound: small cut around 2 to 4 kHz. This area is where ears are most sensitive, so make small moves.
- Sibilant, spitty vocal: a narrow cut between 5 and 8 kHz, or a de-esser if the desk has one.
If the problem is feedback rather than tone, EQ is the wrong tool to reach for first. Position and gain structure come first, and that is covered in how to stop feedback and gain staging.
Popular picks from the shop
Frequently asked questions
Should I EQ every channel?
No. High-pass almost everything, then leave a channel flat unless it has a problem you can name. Reaching for EQ on a channel that already sounds right is how mixes get worse.
What is the difference between a high-pass filter and turning the low band down?
The filter removes everything below a point at a steep slope. The low band is a gentle shelf or bell that reduces a range but leaves plenty behind. For rumble you want the filter.
Why does everything sound worse after I EQ it?
Usually boosting rather than cutting, and usually too much. Try setting every band back to flat, engaging the high-pass, and making one cut. Most channels need one move, not four.
Do I EQ the channel or the main output?
Fix problems at the channel where they start. Output EQ is for the room, and on a small system it is better used to tame one or two obvious room resonances than to reshape the whole mix.
