EQ
The general audio principles behind equalization or filtering are discussed on the EQ or Filters page. Using EQ before an amp or distortion box to dial in the desired distortion tone is discussed on the Dialing in Distortion Tone page. This page is reserved for using traditional EQ (post-EQ) on a guitar tone, as well as formats and options of EQ units in the guitar realm.
Contents
Amp EQ
Traditionally, EQ is used post-distortion to emphasize certain frequencies vs. others. Since guitar is a highly harmonic instrument and distortion adds even more overtones, EQ changes are likely to be heard regardless of where on the fretboard you are playing. It will affect both low and high notes.
Most amps feature some form of EQ, with it more than likely acting on the signal after any pre-amp distortion. (The big exception is the Mesa/Boogie Mark series, which feature pre-distortion EQ knobs and a post-distortion 5-band graphic EQ.) Modern amps commonly come equipped with Bass, Midrange, Treble, and Presence controls, while older amps typically have a subset of those. Some amps simply have a Tone control, used to change the frequency emphasis from dark to bright. And some have a Mids control that actually sweeps the midrange center frequency, drastically altering how the other controls behave. Some amps' circuitry causes the EQ controls to "interact" with each other, meaning their behavior slightly changes depending on the settings of the other controls. It's always best to do a little research on the particular amp you are tweaking to understand these types of things before you end up tweaking in circles.
- Bass - 60 - 350 Hz
- Mids - 350 - 1,800 Hz
- Treb - 1,800 - 5,000 Hz
- Pres - 3,000 - 10,000 Hz
The popular Mesa/Boogie Mark EQ uses the frequencies: 80, 240, 750, 2200, 5500.
External EQ's
Many guitarists fail to see their tone's EQ in terms of specific frequencies, instead defining it by the cookie-cutter names "bass", "mid", "presence", and "treble", due to such controls being built into most amps. Sure, these names work well when speaking in generalities. But when you want to dial in a specific tone, those amp knobs usually don't cut it. You may want to tweak "between" the knobs, or "narrower" or "fatter" than the knobs allow. Also, the precise frequencies these knobs control vary from amp to amp, forcing you to learn the nuances of the controls on each individual amp. Moreover, these controls don't necessarily adjust only EQ, especially if you are getting some power amp compression/distortion. Sometimes the knobs are gain-staged a certain way, so turning all the controls up to 100% affects tone differently than keeping them all at 50%. I still use those controls; I just don't rely on them exclusively. We can augment the traditional BMTP controls with external devices.
EQ effects come in quite a few varieties. Perhaps the most common are the 5-12 band graphic EQ pedals, such as those made by Boss and MXR (and now Mesa/Boogie). These are nice because they are relatively cheap, provide greater frequency shaping than the Bass/Mids/Treb/Pres knobs of the amp, are compact and portable, are durable, are analog and thus don't create any latency or phase-shifting woes, and can be easily toggled on and off. The only downsides are that they might not provide enough fine-tuning as you like and they are stuck at one setting, requiring you to either purchase more of them or tweak on-the-fly if you need other settings.
While less common, there are other types of EQ's than graphic in the pedal form factor. You may see a 2-3 band notch EQ or a 1-2 band parametric. I really like parametrics due to their ability to be dialed in exactly how you want, but I'm not sure I'd like one as a single-setting pedal.
Also common are large band (~32 band) graphic EQ's in rack format. These expand on the pedal format EQ's and give you much more control. They can be used like a notch EQ to simply dial out a particular band where there's ringing or feedback or fizzy artifacts from a digital device, in addition to general tone shaping. These are nice, but again, they are still stuck in their single setting, and with the rack format may require additional (possibly MIDI) gear to toggle on/off, if they even have a bypass mode.
More recently there have been some programmable digital EQ's popping up, both in pedal and rack format. Many modelers also incorporate similar EQ features, occupying effects slots in the virtual signal chain. These allow you to save EQ settings as a patch, just like in a multi-FX unit or modeler, and switch between patches using MIDI or onboard controls (such as footswitches). The big downside to the standalone units is that they are not cheap. I have also heard the Behringer DEQ2496 has poor durability, which is a shame considering its excellent feature set.
Before deciding you need an external EQ, consider that you may be walking a long, tiring road. You should try to get the most mileage from your amp EQ and/or the EQ on your multi-fx or modeler. If you need the external EQ to hide the warts in your amp/cab/etc. tone, you're basically accepting a bad tone; a better solution may be to consider upgrading amps, speaker cabs, etc. Dialing certain frequencies out may improve the stand-alone guitar tone, but it will also weaken its presence in a mix.
If you need external EQ to tweak between the amp's EQ knobs, an external EQ can work nicely; but if you have multiple tones that all need somewhat different EQ treatment, you are back at either having to purchase multiple EQ's or programming an EQ and getting it to switch along with your amp, possibly requiring a MIDI foot controller.
For recording purposes, you can always rely on DAW software EQ to fine-tune your guitar signal. It will offer more control and likely better quality than any hardware EQ you can buy; plus it can be tweaked long after laying down your guitar track.
For live purposes, you likely aren't worried about getting dozens of completely distinct tones, relying on 2-6 core tones. Set up your EQ to work for your main tone. If your main tone sounds pretty good without EQ, then use it for the next most hard-working tone that absolutely needs it. Either set it up in a compromise manner, where you can leave it always on; or dial it in for one specific tone, and only toggle it on when you need it.
Of course if money and time are no obstacle, get an expensive programmable EQ, a MIDI floorboard, and program all your gear to work off of MIDI switching (may require a MIDI switchable patch bay as well).
Frequency Range Breakdown
| Frequency | Description | General Description |
|---|---|---|
| 0 - 100 | Thump | Bass |
| 100 - 200 | Boom | |
| 200 - 350 | Punch | |
| 350 - 600 | Warmth | Midrange |
| 600 - 850 | Honk | |
| 850 - 1,400 | Cold Djent | |
| 1,400 - 2,600 | Hot Djent | Treble/Presence |
| 2,600 - 5,000 | Fizz | |
| 5,000 - 10,000 | Sizzle | |
| 10,000+ | Broken Glass |
Advice
Unless you are doing something non-traditionally, such as...
- Running a speaker simulator through a real guitar speaker cab
- Using a non-guitar distortion pedal or amp
- Chaining multiple distortions or amps
- Using experimental pickups
- Using non-guitar speakers
...you likely want to start with all the EQ knobs set to 50% or 12 o'clock. This should dial up a basic tone, emphasizing the type of tone the amp was built for. You may not like the tone at first; but before you start turning all kinds of dials, be sure that you are playing at a reasonable volume - your perception of the relative loudness of differing frequencies depends on the overall loudness of the whole tone. I find a tone that sounds good at volumes typically also sounds good at low volumes but not vice versa.
As mentioned in EQ or Filters, it's generally better to cut rather than boost.
How to EQ a Hard Rock Tone
In general the tone should be relatively "flat" with a seemingly equal balance of bass, midrange, and treble - if you try to deviate too far from this, especially with narrow boosts or cuts, the tone will simply sound "off". It might sound good at low-volume or outside a mix, but when cranked it will sound weird, plastic, harsh, or get buried in the mix.
The slight deviations from "flat" will define what kind of tone you have: cold, warm, punchy, crisp, etc. Emphasizing mostly punch will give you a very metalcore chug-a-chug sound. Emphasizing cold djent and dialing back the warmth gives you that cold Meshuggah tone. Hot djent is the key to the older Metallica tone - kind of harsh and very crisp, add lots of bass to make it extremely heavy - the classic scooped thrash tone. Warmth gets you the creamy lead tone, and it can make a sterile-sounding rhythm tone come to life. Honk sounds like really vintage tone - I find it sounds a bit awkward in a modern metal tone but works for classic rock.
You can emphasize combinations of these to dial in what you like best, but don't go too extreme. If your tone's frequency response looks like a saw when viewed through a frequency spectrum analyzer, it's likely to sound goofy. If you want to dial a spot down, it's generally a good idea to do so mildly. If you cut too much, the tone just feels like part of it is missing - it isn't loud or "full" enough. It might sound good at a low volume, but when you crank the volume, you'll find the tone is very harsh or fake-sounding. If I'm cutting I only do so until that spot blends into the rest of the tone, not so that it completely disappears. Yes, even the "fizz".
When I emphasize some frequency range, I'll often boost it with a wide Q, so I'm also boosting the frequencies around it, just not as much. This keeps the tone "in balance".
Neither thump (and boom) nor sizzle should dominate a good guitar tone. It will sound odd to completely dial them out, but they generally get buried in a full mix anyway. I like to de-emphasize them; however, they are often de-emphasized to begin with - guitar speakers (as well as cab/mic sims) tend to roll off the ultra-highs and lows.
If you have any "broken glass" in your tone, you should dial it out. It will be harsh and annoying. If it's just a little; however, you might not even be able to hear it in a mix. Still, it will interfere with the tone of the cymbals and will taint a recording or live performance.
Midrange
Midrange is the most important frequency range for guitar. Very few guitar tones you hear on records are truly "scooped" with the Midrange control on the amp turned all the way down. More likely, a narrow band within the range of midrange frequencies is simply de-emphasized. Novice players, particularly those who enjoy high-gain distortion, often fall into the trap of scooping the hell out of their tone. It sounds great playing in your bedroom by yourself at lower volumes. But when you try to play in a band context at gig-level volume, it either sounds thin and "buried" in the mix, or extremely harsh and clashes with the cymbals. I speak from experience.
I think this immediacy towards scooping comes from trying to make one's guitar tone sound like a full mix. In a mix, the bass and kick drum fill in the low end, while snare and cymbals fill in the high end. Vocals tend to occupy the upper midrange area. That big gaping whole between the bass and vocals and/or cymbals needs to get filled in by guitar.
With these things in mind, you can still scoop some mids and get a killer tone that still works in a mix. You just have to be a bit conservative on how much mids you cut. Its best to get crafty and use a parametric EQ to cut exactly at the frequency you want to dial back, making the cut as narrow and shallow as possible. You only want to reduce the emphasis of those frequencies, not kill them completely.
Also, if you find you have to really scoop the mids to get some unwanted "honk" out of the tone, you may be able to offset this by boosting the midrange on each side of this cut. For instance, if you are cutting 750 Hz, you can boost at 375 Hz and 1,500 Hz to keep the midrange as a whole in balance with the bass and treble.
Common EQ Techniques
- Scooped Mids - some metal players like to cut mids around 600-900 Hz to remove the vintage-sounding "honk" from the tone. This can make the tone sound meaner and more modern, but it is also regarded as a trap that bedroom players commonly make. The core of the guitar tone is midrange while the other frequencies tend to clash with other instruments in a mix. Also, at high volumes, the human ear is more sensitive to low and high frequencies, making a "mean" tone at bedroom volume sound harsh and droning at gig-level volumes. You can still scoop some mids to get a modern tone that sounds good in a band situation, but you can't overdo it.
- Low Pass - A low-pass filter is commonly used to filter most frequencies past 8 or 9 kHz, which for a guitar tone are rather noisy and harsh.
- High Pass - A high-pass filter is commonly used to filter most frequencies below 60-150 Hz, which for a guitar tone are generally loose and droning and interfere with the bass player.
- Presence Boost - a boost around 1,500 or 2,000 Hz can help a guitar tone cut through the mix, particularly for solos.