Filter Types
High-Pass Filter (HPF)
Vocabulary
High-Pass Filter (HPF)
A filter that cuts everything below a set frequency and lets everything above pass through. The most-used filter in mixing. On every track except kick and bass, a high-pass filter removes low-end content that doesn't belong — room noise, mic handling, HVAC hum, proximity effect.
A high-pass filter cuts everything below a set frequency and lets everything above it pass through. This is the most-used filter in mixing. Almost every track in a mix should have a high-pass filter removing the low-end content that doesn’t belong there.
A vocal doesn’t need anything below 80–100 Hz. An acoustic guitar doesn’t need anything below 60–80 Hz. Even a snare drum can be high-passed at 80 Hz without losing impact. Removing that low-end rumble (room noise, mic handling, HVAC hum, proximity effect) cleans up the entire mix. Watch: High Pass Advantage
The exception: kick drum and bass. These instruments own the low end. Don’t high-pass them unless you’re deliberately thinning them for a specific effect.
Low-Pass Filter (LPF)
Cuts everything above a set frequency. Less commonly used than HPF, but valuable for removing high-frequency harshness, hiss, or digital artifacts from tracks that don’t need air. A bass guitar doesn’t need anything above 5–8 kHz. A pad synth might not need anything above 10 kHz if the cymbals and vocals are covering that space.
Bell (Parametric)
A bell curve boosts or cuts a specific frequency range defined by three parameters: frequency (center of the curve), gain (how much you boost or cut), and Q (how wide or narrow the curve is). High Q = narrow surgical cut. Low Q = broad gentle shape.
Use narrow Q for surgical problem-solving (a resonant ring at 650 Hz on the snare, a boxy frequency at 400 Hz on the vocal). Use wide Q for tonal shaping (brightening a track with a broad boost around 10 kHz, warming a vocal with a gentle boost around 200 Hz).
Shelf
A shelf boosts or cuts everything above (high shelf) or below (low shelf) a set frequency. Unlike a bell, a shelf doesn’t come back down — it changes the entire top or bottom of the frequency spectrum.
High shelf at 8 kHz with a 3 dB boost: everything above 8 kHz gets brighter. Low shelf at 200 Hz with a 2 dB cut: the entire bottom end gets thinner. Shelves are great for broad tonal changes that feel natural and musical.
The VIP Range
Vocabulary
VIP Range
The frequency band between roughly 200 Hz and 4 kHz where most of the musical information lives. Vocals, guitars, keyboards, and snare drum body all compete here. This is where clarity is won or lost — and where most muddy or harsh mixes have their problems.
The frequency range between roughly 200 Hz and 4 kHz is where most of the musical information lives. Vocals, guitars, keyboards, snare drum body — they all compete in this range. This is where clarity is won or lost.
When a mix sounds muddy, the problem is almost always in the 200–500 Hz range — too many instruments piling up with overlapping low-mid energy. When a mix sounds harsh, it’s usually in the 2–5 kHz range — too many things fighting for presence.
Mixing in the VIP range is about subtraction: carving small cuts in each track so instruments don’t mask each other. The vocal gets its pocket. The guitar stays out of the vocal’s way. The snare occupies a slightly different slice than the keyboard.
The Subtractive Approach
Start every EQ move by asking: “What’s wrong with this sound?” Not “What can I add?” If you can’t hear a problem, the track might not need EQ.
When you do hear a problem:
- Find it. Set up a narrow bell with a big boost (+10–12 dB). Sweep it slowly across the frequency range. When the problem gets louder, you’ve found it.
- Cut it. Switch from boost to cut. Narrow the Q to target just the problem area. Cut 2–4 dB. Listen in context (not soloed) to hear if the fix works.
- Stop. Don’t keep EQing for the sake of EQing. If the track sounds good now, move on.
This “boost to find, cut to fix” technique is the single most useful EQ skill you’ll develop. But don’t overdo the hunt. If something doesn’t bother you, don’t go looking for problems. Use the sweep only when you hear an issue but can’t identify the exact frequency.
Frequency Carving
Vocabulary
Masking
When two instruments occupy the same frequency range and neither is clearly audible — they fuse into a smeared blob. The solution isn't making both louder. It's making each one different by carving complementary EQ pockets so each instrument's character comes through.
Two instruments occupying the same frequency range will mask each other. Neither will be clearly audible — they’ll fuse into a smeared blob. The solution isn’t making both louder. It’s making each one different.
Find the core frequency of each instrument — the range that gives it its character — and make sure no other instrument is competing there. Vocal clarity lives around 2–4 kHz. Snare crack lives around 3–5 kHz. Guitar body lives around 200–800 Hz. If the guitar’s body is masking the vocal’s warmth, cut the guitar slightly in the 200–400 Hz range. Don’t boost the vocal to compete — remove the competition.
Describing Frequencies
Learning to describe what you hear in frequency terms accelerates everything:
| Range |
What You Hear |
Common Labels |
| 20–60 Hz |
Sub-bass rumble, felt more than heard |
Weight, thud |
| 60–200 Hz |
Bass body, kick punch, warmth |
Boom, warmth, thickness |
| 200–500 Hz |
Low-mids, body, mud |
Boxy, muddy, woody, full |
| 500 Hz–2 kHz |
Midrange, nasal, honk |
Honk, nasal, telephone |
| 2–5 kHz |
Presence, clarity, edge |
Bite, presence, aggression |
| 5–8 kHz |
Sibilance, brightness, detail |
Harsh, crisp, sibilant |
| 8–16 kHz |
Air, sparkle, breathiness |
Air, shimmer, sparkle |
When someone says “the mix sounds muddy,” they’re pointing at 200–500 Hz. “Harsh” means 2–5 kHz. “Thin” means the low-mids (200–500 Hz) are missing. Building this vocabulary lets you diagnose problems faster and communicate with other engineers.
The HPF Sweep
On every track except kick and bass, engage a high-pass filter and sweep it upward from 20 Hz until you hear the sound change. Then back off 10–20 Hz. That’s your HPF setting — below that frequency, the track was contributing nothing but mud, rumble, and headroom consumption.
For vocals, this is usually 80–120 Hz. For acoustic guitar, 60–100 Hz. For toms, 60–80 Hz. For overheads, 100–200 Hz (they’re for shimmer and width, not low end). For synth pads, often 150–300 Hz depending on the arrangement.
The cumulative effect is dramatic. Individually, each HPF removes content you can barely hear. Together, they clear out a massive amount of low-frequency buildup that was masking your kick and bass. Watch: Packing Light: HPF at Mic Pre or Post
Surgical vs. Broad
Know when to use each:
Surgical (narrow Q, 2–4 dB cut): Use for specific problems — a resonant ring, a boxy frequency, a harsh peak. Find the problem frequency precisely and cut it without affecting the surrounding spectrum.
Broad (wide Q, 1–3 dB): Use for tonal shaping — making a track warmer, brighter, thinner, fuller. A gentle broad boost at 10 kHz adds air naturally. A narrow spike at 10 kHz sounds brittle and unnatural.
Most EQ moves in a mix are small. If you’re routinely boosting or cutting more than 4–5 dB, something is wrong upstream — bad mic choice, bad arrangement, wrong sound selection. Fix the source, not the symptom.
EQ and Compression Order
The order of EQ and compression in your insert chain matters:
EQ before compression: The compressor responds to the EQ’d signal. If you boost the low-mids before the compressor, the compressor triggers more on low-mid energy. This shapes how the compression behaves.
EQ after compression: The compressor responds to the raw signal, then the EQ shapes the compressed result. This is more transparent — the compression doesn’t react to your EQ moves.
There’s no universal right answer. Try both on each track and listen. Many engineers use two EQs — one before the compressor for problem-solving (HPF, surgical cuts) and one after for tonal shaping (boosts, shelves). Watch: Dynamics and EQ: Connected
Choosing Your EQ
Different EQ plugins have different characters:
Clean parametric (stock DAW EQ, FabFilter Pro-Q): Transparent, precise, surgical. Use for problem-solving and precise sculpting.
Analog-modeled (Pultec, Neve, API, SSL): Colored, musical, with built-in harmonic character. The Pultec can boost and cut at the same frequency simultaneously, creating a unique resonant shelf. Analog EQs aren’t better or worse — they’re different tools for different jobs.
Dynamic EQ: An EQ that only engages when the frequency exceeds a threshold. Combines EQ with compression behavior. Useful for taming a harsh frequency that only appears on certain notes or syllables.
Vocabulary
Dynamic EQ
An EQ that only activates when a specific frequency band exceeds a threshold. Unlike static EQ (always on), dynamic EQ responds to the signal — it cuts 3 kHz only when it gets too loud, leaving it alone the rest of the time. More transparent than static EQ for intermittent problems.
Get comfortable with your DAW’s stock EQ first. It’s transparent, flexible, and CPU-efficient. Add analog-modeled EQs when you want coloration and vibe.
Soloing vs. Context
A common mistake: soloing a track, EQing it until it sounds great in isolation, then unsoloing and finding it doesn’t fit the mix at all. A snare that sounds full and warm soloed might sound muddy in context. A vocal that sounds thin soloed might sit perfectly when the guitars and bass fill in the low end. How things sound in isolation doesn’t have much to do with how they work in context.
EQ in context whenever possible. Use solo briefly to identify a specific problem, then switch back to the full mix to confirm the fix works there. The mix is the only context that matters. This is another argument for mixing with faders low — rather than soloing, you can push something up above the fray and hear it in context without losing the whole picture.
What to Practice
- High-pass every track in a mix except the kick and bass. Start conservatively (40–60 Hz) and push higher until you hear the track losing weight. Back off slightly. Notice how the overall mix clarity improves.
- Use the “boost to find, cut to fix” technique on three tracks. Sweep a narrow +12 dB bell across the spectrum, find the worst frequency, and cut it 3–4 dB. Listen in context to confirm.
- Pick two instruments that compete in the same frequency range (guitar and vocal, or kick and bass). EQ them to carve complementary pockets — boost one where you cut the other. Watch: Targeting EQ
- Mix an entire song with only subtractive EQ — no boosts, only cuts. Notice how the mix opens up through subtraction alone.
