View Full Version : Basics of EQ

9450 Mastering
2005-02-08, 11:40 AM
Rain Dawg is a previous post asked me to share some of my "remastering techniques" (use it lightly, please). This is the first step I use when I get a show.

For simplicity I use Adobe Audition 1.5, I do have a dedicated Sonic Solutions setup but that I think does a bit too much..another time.

I dont like to really mess with a show too much, I think it detracts from the recording made. So I really try to focus on what might be called "enhancement" which can be taken a number of ways.

Alot of what comes my way is great, I tend to lean towards the older stuff, sometimes hissy sometimes crackly, and pretty high generation. Back in my old tape trading days, alot of the stuff sounded like it was taped with a kmart boombox, some taped by the greats who cared.

No one room is alike. The sound is different when the venue is empty vs full. Mics have different ranges and sounds. Frequences of eq are trapped in certain areas of the venue, and live mics pic them up. Which can make the sound boomy, flat or just right. They get it all, even the dead spots. Also it depends on the engineer, room humidity and alot of other physics things.

My theory is that there are dead spots in the room and by simple adjustments some gains can be made. Some cant or dont need to be done. If it aint broke dont fix it. Too much adjustment can leave nice little washy nuggets we all love. Especially if one uses sound soap or adobe's noise reduction. So i try to hit it with the eq first. Not too much but by increments. Good Monitors help too. But I dont try to get too happy with it. It is on a case by case basis. By tinkering you can find out where an instrument is too quiet and try to bring it out in the frequency bands mentioned below.

On a show I got recently the drums sounded too loud in the lower end but the rest of it sounded perfect. I tinkered and shaped the lower end so it did not sound flat. Shazam there was a band in there. I just dont set it and forget it, each song needed some adjustment. And that is where a good ear helps. Because it can come out one is louder than the other, more distorted, etc. So I try to keep an average setting and work within that boosting or in the most part cutting frequencies. But when you do this be prepared for the other frequencies in the spectrum to react, less drums means more high end, etc.

This is by no means a definitive means of doing it, but a simple method I use.
Dont get too crazy is a rule of thumb. I per say hate over processed shows and I can tell right off if it has been tinkered with too much, less is better. I think the bertha remasters have this down pat.

The biggest enemy is room reflection in traded shows, position etc. And with some simple eq that usually can fix the dead spots. So below is a simple guide to where things live, subjective of course. It takes time to get it right and my only advice to someone new to this is not to go off seeding just yet, listen on a different stereo, in the car and maybe take some notes, this is too high or too boomy. Mids are out of whack. It takes time to get a good balance. I have stuff I have worked on for months and I dont think it is right yet, but I look at it as good practice to achieving a good mix.

My expereince has come from 17 years as a sound engineer. And I can pick out frequencies pretty fast. Enhancing the shows and actually mixing live are two different birds I can say.........

So below is a good guide for EQ......

Equalization is the most-used, most-mis-used, most-over-used and most-under-used signal processing device. It is also the most powerful. By definition an equalizer is a gain control that raises or lowers gain at a specific set of frequencies without affecting the gain at other frequency ranges.
I learned a lot about equalization by sitting down with a graphic equalizer and lots of records. After about 30 hours of listening to the effect of different bands of equalization on the records, I began to "hear" the effect of certain frequencies on overall mixes. Since I have a job in mastering, this was a direct application as to how I was going to use equalizers.
Doing an exercise like this is the very beginning of training in using equalization. There are commercial CD packages which attempt to duplicate this type of test. They are no real substitute for switching the equalization on and off as the CD (or music source) plays.
The next step in the training is to apply specific equalization to specific instruments. Recommended or "key" frequencies are used and the equalization is switched on and off while soloing the instrument and then while listening to the instrument in the mix.
The point of this "ear" training is to gain the ability to hear what frequencies would be needed to bring up or down in a specific mixdown. Until one obtains the ability to "hear" frequency, one has only limited ability to use equalization.
Frequency Ranges:
A key to understanding equalization is to gain an understanding of the effect of different frequency ranges on music and instrument sounds.

The "First Octave"

The first usable octave for most recording is the 40 - 80 Hz range, with equalization settings centered around 50 Hz. This range of frequencies is often referred to as "Low Bass"
There is sound between 20 Hz and 40 Hz but little or no sound from instruments. The lowest pipes of a pipe organ will get into this range but more "ordinary" instruments like Bass Guitar,

Upright Bass and Foot Drums do not. The lowest pitch on a bass guitar or string bass is at 41 Hz. Thunder, earthquakes and rumble from the building shaking extend below 40 Hz. While mixing, watch out for objectionable sounds below 40 Hz caused by building shifts and mic stands moving with heavy footsteps. If there is objectionable sounds in this range, the range can usually be taken entirely out with a filter.
The first octave that we deal with (40 - 80Hz) gives more of a "feeling" and sense of "power" to the sound. This range is way down or non-existent in smaller stereo systems. This range is difficult to hear at all at medium and low volume levels because of the Fletcher Munson Effect.
To properly set the amount of low bass in your mix or in your instrument sound, you must listen both loud and soft. You also may want to listen to the mix or instrument on large and small speaker systems. Too much energy in this range will make the mix sound muddy on large speakers played loud and still sound good on small speakers played at a medium volume. You want the mix or instrument to sound larger and more powerful over large speakers without sounding muddy.
Rap, Hip Hop and "Dance" music (under various names) often have extra energy in the low-bass range. This is what causes cars equipped with sub-woofers to shake. Usually, however, it is not the entire mix that is boosted below 80 Hz, but just, for example, the foot drum. By boosting the energy on only one or two instruments, "clarity" can be achieved without "mud."

The Bass Range

Covering about 1.5 octaves, from 80 Hz to 250 Hz, this range of frequencies determines the "fatness" and "fullness" of the instrument's sound. Equalization is usually applied centered around two frequencies, 100 Hz and 200 Hz.
For guitars and bass, the 100 Hz range tends to add body and fullness. Excessive energy in this range tends to make these instruments sound "boomy.," This range of frequencies is still greatly affected by the Fletcher-Muson Effect; this means you will need to listen to the mix and instrument both loud and soft. Similar to how the 50 Hz range affects the bass and foot, the guitars should sound fatter when played loud, not boomy. Reducing the 100 Hz energy on the guitar will usually cause distinction between the bass and guitar parts. The lowest fundamental frequency on a guitar is around 80 Hz.
For vocals the 200 Hz range determines the fullness of the vocal. This range can often be reduced to increase distinction on the vocal. If, however, boosting in higher frequencies on the vocal makes the sound "thin" or "small" a boost of 200 Hz. will restore fullness.
When 100 Hz is reduced on a guitar or bass to reduce "boom," at small boost at 200 Hz can be helpful to keep the instrument from sounding "lumpy" (certain notes hard to hear and others standing out). The guitar and bass have almost equal energy at their fundamental and 2nd harmonic frequencies. Thus if a range of notes becomes hard to hear because of a at lot of 100 Hz, reducing energy at 100Hz and adding energy at 200 Hz will help the notes be heard again.

The Bass Presence / Lower Mid Range

Covering about one octaves from 250 Hz to 500 Hz, this range accents ambience of studio and adds clarity to the bass and lower-string instruments (Chello and Upright Bass). Too much boost can make higher-frequency instruments muffled sounding and low-frequency drums (foot and toms) have a cardboard box quality. Equalization in this range is applied at many frequencies but most often between 300 Hz and 400 Hz.
The lower part of this range (250 Hz to 350 Hz) is sometimes referred to as "Upper Bass" and is used to increase distinction and fullness on the vocal, especially on female singers.
The Lower Mid Range in general can be viewed as the "Bass Presence Range" Increasing this range gives clarity to the bass line and the lower-register of pianos and organs. Clarity and distinction can be obtained between the foot drum and bass guitar by both reducing the foot and increasing the bass guitar in this range, at the same frequency.
This range is often reduced for overhead drum and cymbal microphones to increase clarity and presence on these instruments' and reduced on lower drums (foot and toms) to reduce boxiness.

The Mid Range

The Mid Range band of frequencies covers two octaves from 500 Hz to 2 kHz. This range can give a horn-like quality to instruments (500 Hz to 1 kHz) and a "tinny" sound (1 kHz to 2 kHz) or a telephone-like quality (all of the range). Equalization usually centers around 800 Hz and 1,.5 kHz.
The mid-range also tends to accent the presence (800 Hz) and attack (1.5 kHz) of the bass guitar. The lower pitches of a rhythm guitar can be given more attack by a boost at 1.5 kHz.
For your Mid Range Instruments (vocals, guitars and piano) this range is most-often reduced rather than accented. Reducing 500 - 800 Hz on an acoustic guitar can remove the "cheep" sound and make it sound more "silvery." Reducing 800 Hz on a vocal makes it sound less nasal and have more body and presence. For snare drums, a reduction of 800 Hz can take the tinny, cheep sound out of the drum and make the snares have more sizzle rather than rattle.

The Upper Mid Range

Covering about one octave, this range of frequencies is responsible for the attack on percussive and rhythm instruments and the "projection" of mid range instruments. Equalization can be applied at any frequency in this range but still somewhat centers around 3 kHz.
On the foot drum, boosting 2.5 kHz or 4 kHz increases the attack. 2.5 kHz sounds more like a felt beater and 4 kHz sounds more like a hard-wood beater. These frequencies can also be used to increase the attack or "hit" sound on toms and snare drums.
Guitar lines often get more attack and distinction with equalization added at this range. A small boost (1-3 dB) for the vocal will increase projection. Adding too much energy, in this range, makes it hard to distinguish the syllables of the vocal and can cause listening fatigue. This range of frequencies is often reduced on background vocal to give them a more "airy" and "transparent" sound.

The Presence Range

Although this range covers a mere half-octave of 4 kHz to 6 kHz, it is an often-used band of frequencies. This range makes most vocals and melody instruments sound closer and more distinct. Over-boosting causes a irritating and harsh sound. Equalization centers around 5 kHz.
The Treble Range

Covering approximately that last two octaves of sound (6 kHz to 20 kHz), this band of frequencies is responsible for the brilliance and clarity on instruments. Equalization centers around 7 kHz, 10 kHz and 15 kHz.
The vocal "S" sounds are at about 7 kHz, making this a frequency that is avoided for vocals. Care must be exercised in reducing 7 kHz on vocals, however, because the vocal will sound dull very fast. The breath sound of the vocal is at 15 kHz and above, giving a breath quality without much accent on the "S": sound of the vocal.
The 7 kHz frequency is also the "metallic attack" frequency on drums The "sizzle" of cymbals is at 15 kHz.
When equalizing, 10 kHz and above is often used as a general "brilliance" frequency band.

2005-02-08, 06:01 PM
Excellent explanation of the spectrum, and where you'll find specific instruments.

I'd probably include a graph or 2 to explain what happens when you cram all this sound together into a single track or stereo mix, and the difficulty of applying proper equalization to isolated instruments after everything is smashed together. It also helps to have an understanding of harmonics, especially since much of the material is recorded in "live rooms", and there are pronounced artifacts introduced in these "ambient" recordings. An understanding of compression and band dependent triggering would be cool too. :cool:

2005-02-08, 09:40 PM
Many, many thanks for this. It's is a great intro into a complex subject. I'm seriously thinking of getting the Peak and SoundSoap combo for the Mac (I have a lot of 60s and 70s AUD shows that should benefit from some EQ) and your guide gives me a intro for starting to tinker.

9450 Mastering
2005-02-09, 09:48 AM
I'll put together a guide for compression, which is a sticky subject.......and get some graphing up too. Hopefully tonight.

2005-02-09, 11:21 AM
very nice

You're mentioning a small boost at 200hz can be helpful from time to time, what I've read and found from experience is that this frequency is also the home of mud and needs to be treated very carefully. Sometimes a small cut at this frequency can help to make the lows more distinct from the low mids.

2005-02-09, 03:32 PM
While we're on the subject: it should be noted that filters like equalization - and speed correction, balance and compression - are computationally inexpensive (by today's standards anyway) and can be applied to sources on the fly during playback on a computer..

No real need to set things in stone imo, especially not if they're so much of a matter of taste.

Anyway, that was an excellent informative post, 9450 Mastering. Thanks a lot.

2005-02-11, 09:12 AM
Yes, thank you for the post. I'm glad to see some in depth conversation of remastering here. I wish I had time to give a more detailed response, but I'll just briefly say that it's a very informative tutorial and I hope you get the time to post some more.

2005-04-17, 08:28 PM
whew, i was looking all over the place for this very informative thread, damn glad i found it....

2005-04-21, 10:36 AM
damn glad jcrab found it too! that was quite a concise and easy to follow EQ breakdown! thanks!

2005-06-13, 01:58 PM
This is a brilliant post!!

Thank you very much for all this great data. If you ever get teh time I look forward to your compression guide. THanks!!@<hidden>#$

2005-06-24, 01:40 AM
This is a very informative Thread, Thank You!

2005-12-04, 02:00 AM
The best piece of advice I can give when remastering a show using equalization methods is to follow a "v" shaped pattern, usually decreasing the midrange at first, and gradually sloping upwards to the low bass and high treble frequencies. Setting those is where the real art begins. Don't decrease the midrange too much, all you'll do is compress the sound down, and the result will sound "flat".

When adjusting the levels of guitar type music, this is usually helpful, but other methods work great as well.