EQ - Sound Frequencies

The Very Bottom End

20-40hz is generally out of instrument range*. Nothing desirable can come from a boost in this range, unless you want the rumble of an earthquake, thunder or anything else earth shaking. Most sound systems don’t even go this low and all you will do is soak up valuable headroom. It is best to filter out this area completely and avoid wasted power due to low frequency rubbish.

* (OK before some wiseguy points it out, the fundamental of a grand piano (A0) is 27.5Hz but believe, in real world situations, me nobody really hears the actual fundamental).

The Bass

40-200Hz

Fundamentals of rhythm section. EQ can change musical balance making it fat or thin. Too much makes music boomy.

40hz to 80hz

The 1st octave is the sub-bass of the “feel” of the bass, gives a sense of power, felt more than heard.. An important range for hip-hop, dance or electronic music.

Deep bass requres a lot of energy to produce, these frequencies are for sub woofers or large speakers. Small sound systems and stage monitor frequency response rolls off in this region and there can be a danger of boosting the bass to overcompensate for poor bass response.

Using a bell shaped response rather than shelving is often preferable if a boost is required, centred around 60-80Hz this will add the weight without introducing too much low frequency mush.

It usually is enough to boost just the bassline or bass drum or both to get some nice tight powerful bass, boost on many tracks in this area can easily over power the everything else. Other instruments are often completely filtered out in this range.

100hz - A boost around can often add fullness and punch to a thin sound, but it is also known as the the boom frequency. Often guitars or other instruments will sound boomy and a cut at around 100hz will remove that quality. It is here that bass and guitar tend to blur together, cutting the guitar here helps separate the two.

The Low Midrange.

200Hz-600Hz

The borderlands between bass and mid: The muddiness region or 'mudrange'.

200Hz-250Hz - can add fullness to vocals but also muddy things up so it's a good place to cut on muddy vocals. Keep to small reductions or boosts in this range to much can easily become too drastic.

Mud and fullness of other acoustic instruments hang out around here also. Slight boosts in this range to fill out a thin sounding acoustic guitar is common.

250Hz-600HzGives fullness to some vocals and percussion, snares in particular. The gong sound of cymbals can be found here.

250Hz to 400Hz - A cut around here can cure a cardboard box sound in the kick drum or other low register percussion. This is also a good area to get space between the bassline and kik drum.

The Midrange.

600Hz-4kHz

Subtlety is required here, sound can really get mushy in this range so it can take some work to get everything to fit, and it is also easy to induce ear fatigue in this range.

This the range in which edgey and aggressive sounds come from, but even if you are making aggressive music it is an extremely fine line .

500-1KHz - is the region where tube and horn-like effects lie.

800Hz is the area most often reduced to remove that cheap sound in some instruments. An excess here is notable in terms like cheap, plastic, tinny, toy sounding, unmusical, It can be the area to boost or reduce the punchiness of a bass guitar though.

1-2kHz - Tinny sounds, too much here creates listening fatigue.

2kHz-4kHz - The attack of some instruments can be accentuated or diminished here and in particular, the attack of the beater hitting a percussion instrument. This is also a very important area for speech recognition.

3KHz - Too much here creates listening fatigue, to little little can lead to lisping quality, "m:, "v", "b" become indistinguishable.

The Presence Region

4kHz-6kHz

The range usually refered to as presence.

This area affects how close the sound seems and can help separate a sound from the rest of the mix. Defines much of the clarity and definition of voices and instruments. Where you boost to make vocals or instrument solos seem “up front. The region of the presence knob on a guitar amp.

Adding 6dB at 5KHz can make the entire mix seem 3dB louder, but too much level here on anything can easily become grating and induces listening fatigue very quickly.

The High End

6KHz-16kHz

Brilliance and clarity of sounds. Sibilance, harshness on vocals.

7k-8kHz is where the brightness of cymbals and other high register percussion is, often referred to as the shimmer or sizzle. It can add some bite to some other instruments, but too much boost in this area can produce a metallic sound.

7kHz is the nasty realm of sibilance, the “s” sound area of the frequency spectrum. This is where the unpleasant and sometimes overpowering “s” sounds in vocals are to be found.

8kHz and above : The range of “air” or “brilliance”, and it is here a sound brightened up and sparkle added. This is where you boost or cut the breath sound. and also where the brittle,'ice pick' sound can be tamed.

10k is a good starting point to look at adding some brilliance.

15k and above is more the area referred as “air.”

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