Why Broad EQ Can’t Save You

You can’t do microsurgery with an axe.

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The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

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I don’t have anything against “British EQ” as a basic concept. As I’ve come to interpret it, “British EQ” is a marketing term that means “our filters are wide.” EQ filters with gentle, wide slopes tend to sound nice and are pretty easy to use, so they make sense as a design decision in consoles that can’t give you every bell and whistle.

When I’m trying to give a channel or group a push in a specific area, I do indeed prefer to use a filter that’s a bit wider. Especially if I have to really “get on the gas,” I need the EQ to NOT impart a strange or ugly resonance to the sound. Even so, I think my overall preference is still for a more focused filter than what other folks might choose. For instance, when adding 6 dB at about 1kHz to an electric guitar (something I do quite often), the default behavior of my favorite EQ plugin is a two-octave wide filter:


What I generally prefer is a 1.5-octave filter, though.


I still mostly avoid a weird, “peaky” sound, but I get a little bit less (1 dB) of that extra traffic at 2-3 kHz, which might be just enough to keep me from stomping on the intelligibility of my vocal channels.

Especially in the rough-and-tumble world of live audio, EQ selectivity is a big deal. When everything is bleeding into everything else, you want to be able to grab and move only the frequency range that corresponds to what’s actually “signal” in a channel. Getting what you want…and also glomming onto a bunch of extra material isn’t all that helpful. In the context of, say, a vocal mic, only the actual vocal part is signal. Everything else is noise, even if it’s all music in the wider sense. IF I want to work on something in a vocal channel, I don’t also want to be working on the bass, drums, guitar, and keyboard noises that are also arriving at the mic. Selective EQ helps with that.

What Your Channel EQ Is Doing To You

Selective EQ isn’t always a choice that you get, though. If a console manufacturer has a limited “budget” to decide what to give you on a channel-per-channel basis, they’ll probably choose a filter that’s fairly wide. For instance, here’s a 6 dB boost at 1 kHz on a channel from an inexpensive analog console (a Behringer SL2442):


The filter looks to be between 2.5 and 3 octaves wide. This is perfectly fine for basic tone shaping, but it’s not always great for solving problems. It would be nice to get control over the bandwidth of the filter, but that option chews up both what can be spent on internal components, and it also hogs control-surface real estate. For those reasons, and also because of “ease of use” considerations, fully parametric EQ isn’t something that’s commonly found on small-venue, analog consoles. As such, their channel EQs are often metaphorical axes – or kitchen knives, if you’re lucky – when what you may need is a scalpel.

If you need to do something drastic in terms of gain, a big, fat EQ filter can start acting like a volume control across the entire channel. This is especially true when you need to work on two or more areas, and multiple filters overlap. You can kill your problem, but you’ll also kill everything else.

It’s like getting rid of a venomous spider by having the Air Force bomb your house.

I should probably stop with the metaphors…

Fighting Feedback

Of course, we don’t usually manage feedback issues with a console’s channel EQ. We tend to use graphic EQs that have been inserted or “inlined” on console outputs. (I do things VERY differently, but that’s not the point of this article.)

Why, though? Why use a graphic EQ, or a highly flexible parametric EQ for battling feedback?

Well, again, the issue is selectivity.

See, if what you’re trying to do is to maximize the amount of gain that can be applied to a system, any gain reduction works against that goal.

(Logical, right?)

Unfortunately, most feedback management is done by applying negative gain across some frequency range. The trick, then, is to apply that negative gain across as narrow a band as is practicable. The more selective a filter is, the more insane things you can do with its gain without having a large effect on the average level of the rest of the signal.

For example, here’s a (hypothetical) feedback management filter that’s 0.5 octaves wide and set for a gain of -9 dB.


It’s 1 dB down at about 600 Hz and 1700 Hz. That’s not too bad, but take a look at this quarter-octave notch filter:


Its actual gain is negative infinity, although the analyzer “only” has enough resolution to show a loss of 30 dB. (That’s still a very deep cut.) Even with a cut that displays as more than three times as deep as the first filter, the -1 dB points are 850 Hz and 1200 Hz. The filter’s high selectivity makes it capable of obliterating a problem area while leaving almost everything else untouched.

To conclude, I want to reiterate: Wide EQ isn’t bad. It’s an important tool to have in the box. At the same time, I would caution craftspersons that are new to this business that a label like “British EQ” or “musical EQ” does not necessarily mean “good for everything.” In most cases, what that label likely means is that an equalizer is inoffensive by way of having a gentle slope.

And that’s fine.

But broad EQ can’t save you. Not from the really tough problems, anyway.