Get Your Curve On

The humps and valleys of a humble EQ plug-in can help you achieve that perfect sound
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The humps and valleys of a humble EQ plug-in can help you achieve that perfect sound


Author Mo Volans has prepared an example MP3, and a full screenshot for three types of EQ functions in this feature on three EQ plug-ins: Apple Logic Channel EQ, Universal Audio Cambridge EQ and PSP Neon. Go to the MP3s, and a full screenshots

With the vast array of plug-ins available today, it's all too easy to overcook a mix. Beginner or pro, we all have access to some pretty impressive — and sometimes bizarre — processors with DSP power to burn. You easily can have several enhancers, tube emulators and vintage-style compressors on every track in your production in the attempt to reach mix nirvana. While there is definitely a time and place for that approach, if you overdo it, you could end up sinking in audio mud. In most cases, the answer doesn't lie in yet another plug-in or a secret trick but in good basic EQ and compression technique. In traditional recording, there is no substitute for good performance and sound-recording practices, but looking at things from purely a mixing point of view, these tips should help you clean up your act.

In each of the three following scenarios, I ran the same audio file through three EQ plug-ins, showing that the sounds can be achieved regardless of what system you're using. Although all the EQs do have their own character (like any processor), similar results can be had from one EQ to the next. The audio examples, EQ software presets and full screenshots will be supplied for reference at

Each of the three EQ plugs used is fully parametric, meaning simply that all aspects of the EQ are fully controllable (frequency, gain, Q, etc.). They are also all graphical to keep things nice and clear for this exercise. It will be easy to reproduce the same technique on EQs with no graphical readout once you have become familiar with the parameters. The three example EQs include: Apple Logic Studio ($499; Channel EQ, a simple, CPU-efficient EQ that comes standard with the new Logic Studio package; Universal Audio Cambridge EQ (, a pro standard, workhorse EQ that comes with the UAD Ultra Pak ($1,495), Extreme Pak ($2,499) or Xpander Xtreme ($2,599) DSP systems or can be downloaded to UAD hardware owners for $149; and PSP Neon ($149;, a great plug-in that offers basic-to-linear-phase operation to optimize CPU usage in different situations. PSP Neon is reasonably priced for the control and sound quality it offers.


For the first example, I used a house drum loop with a strong kick drum. You often find great loops like this but wish to use it only as a percussion part and program your own kick drum. In such a situation, subtle EQ techniques aren't going to supply the desired results, so you need to apply something a little more drastic.

On all the chosen plug-ins, there is an option to have both highpass and lowpass filters. There are also different curves available on each of the filters. For this example, I used one of the steepest curves available on all the EQs because I wanted to remove everything below a certain point. This extreme approach works well with electronic sounds or drum loops; however, you may want to use a more subtle setting with more organic sounds and instruments such as strings or guitars.

With each EQ's plug-in, I cut all the low end below 200 Hz. This is a technique commonly used in electronic music and is seen by many as an essential procedure to allow the bass elements in your mix to breathe. There is a school of thought that says everything above the bass line and the kick drum should be cut below this area. That process works with some mixes, but it may be too general to apply as a blanket technique to all productions. Try it with some of your own projects to see what works.

In this case, the steep filter does a great job of removing the kick drum and other low-frequency sounds from the loop, resulting in a highly usable percussion part. Once you have processed a drum loop in that way, you can add your own kick drum to give yourself more flexibility during the arrangement process. Of course, you can just automate the filter and use the original bottom end in the loop.

None of the EQ techniques demonstrated here should be limited to certain circumstances. For instance, the extreme filtering technique works well with sampled grooves and top-line synth patterns. You may also like it in a situation where a bad recording or low-quality sample needs to be restored; a great place to start is to filter off any rumble in the bottom end. And remember, the method can be just as useful for attenuating high-end frequencies as well.

The key here is knowing when to use each technique; ultimately, that will come with experience. Once you read this, load the presets and start to understand some of the basics, practice with your own audio and recordings. Eventually, knowing which tool to reach for will become second nature during the mixing process.


Some situations will require a gentler approach. Although hard filtering may be perfect for one sound, it can ruin another. When a sound is closer to what you consider ready, but it needs that extra something, a light shelving EQ can be just the thing you're looking for.

A shelving EQ is exactly what it sounds like: a shelf that is added to the EQ curve, either on the high or low frequencies. Some plug-ins will have the option to shelve more than two of the bands, which can be a transparent way of adding frequencies to a sound, and the organic quality lends itself to real instruments.

I chose a guitar sample for this example. To enhance the sound and help it cut through other mix elements, I added about 5 dB of high-end shelving EQ. I've also taken away some of the lower frequencies using a low-frequency shelf with another 4 dB of cut. You can hear that it really adds clarity without coloring the sound at all. That is a perfect solution when you need to make fine adjustments as opposed to radical changes.

When adding different kinds of EQ, you will start to hear the character or personality of the processor. Much like synthesizers, you will find subtle differences from one EQ to the next. Some will have a clean, transparent feel, while others will add color and harmonics to your sound. It's all about experience and getting to know the plug-ins you have at your disposal.


The most common stumbling block in using a fully parametric EQ is the incorrect use of the “Q” setting. Any fault here is usually due to misconceptions about what these all-important controls actually do. Q really isn't as complex as you may think. At its most basic level, the Q control adjusts the wideness of the frequency band effected by any changes you make. That allows you to home in on a certain frequency with pinpoint accuracy using high settings or make changes over large areas of the frequency range using low settings.

Using high Q values is useful when surgically treating a small area in the frequency range. For instance, say you have a full percussion recording that you like but has one element that is too loud. Try turning the cue point of the closest frequency band relatively low. Once you have this low Q area set, you can turn the gain setting down to the lowest it will go (often -12 dB or -18 dB). You can then sweep the entire frequency band, and you should be able to pick out the exact area that the offending sound occupies.

Once you have located this area, you can start to raise the Q setting until the frequency band only affects the sound you are trying to remove. You can't push that too far because it will result in an over-resonant quality (not surprising as resonant frequencies are essentially what we're dealing with here).

At the same time you're finding the perfect Q settings, try bringing the gain up slowly until the sound you're trying to eliminate starts to reappear. Then you have to take part in a careful balancing act between the right amount of Q setting and the perfect amount of gain.

This technique sometimes pays off, for example, when some of the unwanted signal creeps through and there is a bit of coloration to the rest of the sound. It is also one of the most accurate ways of removing unwanted signals embedded in existing recordings.

For an interesting special effect using high-Q settings, try a high-gain setting and sweep the EQ band you're using across the entire frequency range. That is similar to an automated resonant notch filter. With some automation, that can become a usable creative technique.


Lower-Q settings are perfect for a general approach and tend to be more transparent from the start. As low-Q settings work across a wide section of the frequency range, they aren't suited to treating single sounds but are perfect for boosting groups of instruments.

Due to its qualities, an EQ with low-Q settings perfectly lends itself to applications such as mastering and treating buses. It's important to remember when using an EQ for this purpose that small adjustments are the key. If you find yourself adding more than, say, 3 to 4 dB of EQ in a certain area, it's possible that the fault lies at mix level. It's much better to be listening to the instruments' signals rather than a wash of added EQ.

Although low-Q settings can be used on individual mix elements, you may find them too subtle. That doesn't mean you can't experiment, though, and a healthy Q setting somewhere between 0 and 10 could be the answer.

The audio example demonstrating low Q includes a section of music that is basically mastered but remains flat as far as EQ treatment is concerned. Once you have listened to the dry version, play back the version with EQ. You can see in the screenshots that I added a low-Q setting EQ, boosting the upper-mid frequencies by around 3 dB and another boosting the lower frequencies (peaking at around 100 Hz) by about 1.5 dB. As you can hear, the difference is definitely subtle but is just what was needed in the situation.

Most modern EQ plug-ins are capable of a large range of effects, from extreme to subtle. With all that processing at your fingertips, you must develop a good intuition for which plug-in is right for the job. Now that you have seen some basic techniques, try opening some old projects and looking at your settings. It may also be a good idea to try different plug-ins in place of those already there. Your main advantage will be hands-on experience, so keep practicing. Feel free to e-mail EQ questions to me at

Download MP3s, programmed presets, starting-point presets and full screenshots