Headphone EQ Settings Explained: What Every Slider and Filter Actually Does

If you’re new to the world of equalizing audio gear, there are plenty of settings you might be looking at that both confuse and amaze you. What does this thing do? What does that number mean? We’ve made you a quick reference of what all these adjustments are and what they do. Just remember that how to use these pieces is a whole other topic entirely.

Equalizer types

There are two main types of equalizers that most consumers will encounter: band (or graphic) equalizers and parametric equalizers. Though both are tasked with the same job, they are very different from one another.

Graphic equalizer, or sliders

With most EQ apps on mobile, you’ll likely see a system of slider inputs to adjust specific ranges. These inputs are a bit clunky and don’t allow for very granular control over how you adjust your sound. However, they’re better than nothing and can usually address some of the major issues you’ll find in your music and other content.

These sliders are basically a digital graphic equalizer that applies a small filter for each band. Each slider will adjust a preset range of frequencies, with the label hopefully telling you the center frequency of the affected band. It’s not always clear how nearby frequencies will be affected, but at a basic level, this is how you’ll be making adjustments.

Moving the sliders up will boost the listed range, and sliding them down will cut it. Though this type of interface is limited, it is very intuitive. Just be aware that you won’t be able to use the filter types mentioned below to adjust your tunes. Also, sometimes the bands do not overlap, leaving gaps of frequencies you can’t adjust.

Parametric equalizer

The real magic happens with parametric equalizers, as this type of interface will allow much more advanced controls of your sound. With a parametric equalizer, you can define the exact frequency you want your adjustment to center on, while also defining just how broad or narrow of an adjustment you want to make. This type of interface is definitely a bit more difficult to get right, but once you do, you’ll be able to get much more exacting results than with sliders.

Adding filters to your parametric EQ program can be intimidating, and many people are scared off by having to input lots of numbers or adjust multiple knobs. To make this easier, most wireless headphones that offer parametric equalizers will simplify what you’re able to do a bit so that you don’t go overboard or get lost.

However, online enthusiasts have created other ways to make the process far easier for normal people. Tools like AutoEQ or Squig.link can generate these filters automatically to correct specific models of headphones to certain targets, or allow you to tinker. Some of these tools even allow you to download these filters in a way that popular EQ programs can ingest so you don’t have to manually enter everything in. It’s a lot easier to get a text file from one app to another than it is to fill out several filters by hand!

Adjustment types

Controlling an equalizer isn’t difficult, but it’s important to know what each part does.

There are two main adjustment types when learning how to EQ. Filter adjustments and level adjustments. The first defines the way your adjustment will affect the sound, and the second will define how much your adjustment will alter it.

Level, or gain:

Level adjustments are always expressed in terms of how many decibels you’re boosting the signal with that filter. So, for example, a boost of 5dB is expressed as “5dB,” while a cut of 5dB is expressed as “-5dB.” If that just went over your head, consider this turning up or down the “volume” for certain parts of your sound.

Just remember that you can turn up the volume — but you can’t turn down distortion added by boosting too much in your equalizer. To avoid that, it’s better to cut the frequencies that you want to hear less of than it is to boost the ones you want to hear more of. Though most EQ apps on smartphones won’t allow adjustments to get too crazy here, it’s possible that you could add some minor distortion if you get crazy enough.

Preamp gain:

If you see a setting for “preamp gain,” be sure to bring that setting down by the same amount as your largest boost. For example, suppose you boosted 200Hz by 3dB. In that case, you’re going to want to bring the overall preamp gain to -3dB to ensure that your signal isn’t affected negatively by clipping, distortion, or other annoying consequences of pushing a signal too much. Most smartphone-based apps will do this for you, but if this setting is visible, it probably means you need to input it.

Because setting a negative preamp gain will also reduce the overall level of your signal, don’t be surprised if you have to turn your music up in the system settings after you equalize your headphones.

Filter adjustments:

There are four main parts to filter adjustments:

1. Center frequency
2. Bandwidth
3. Gain
4. Filter type

We’ll take these one by one to make things as easy as possible. Center frequency selects the specific frequency around which you want to center your adjustment. Bandwidth, also known as Q (for quality), refers to how wide the selection is for the adjustments that you want to make — counter-intuitively, the higher the number, the narrower the bandwidth, and vice-versa. Those bass and treble knobs you see in cars will usually have a very low (broad) Q, which looks like a small hill when you’re adjusting it. But if you want to target a very specific frequency range, then having a higher (more narrow) Q will let you achieve this. Gain is the amount of boost or cut that’s applied to the specified range, usually stated in dB.

Filter type refers to the shape of the adjustment. Here are the most common ones for headphones and speakers:

• Peak/Dip filter (PK): A peak filter is bell-shaped when plotted on a frequency response chart. It will apply gain at a center frequency, using the bandwidth to determine the range and shape of the filter.

• Low shelf filter (LS): This adjustment will apply uniform gain to frequencies under the center frequency of the filter. As the name implies, it looks like a shelf when charted.

• High shelf filter (HS): Just like the low shelf, the high shelf will apply uniform gain to frequencies above the center frequency of the filter. It, too, looks like a shelf when charted.

• Low pass: A low pass filter cuts off data above the defined frequency.
• High pass: A high pass filter cuts off everything below a defined frequency.

Each of the above is used for very specific circumstances, but the most common ones you’ll be using are shelf filters and the peak filters. Each of these will have several parameters you need to define in order to be applied. Some settings will not appear on all filters, as they’re not always applicable. For example, a low-pass filter doesn’t need much more than a defined frequency to work. Similarly, some EQ programs will assume a set Q for the shelf filters and don’t offer a way to adjust that number.

Some extra rules to be aware of

As with anything complicated, using an advanced tool requires some extra knowledge to use properly. Here are filter-specific issues to keep in mind:

1. Don’t use peak filters above 10kHz. It can be very easy to unintentionally make tough-to-hear peaks in the highs super loud. Though unlikely, it is possible to damage your hearing with loud sounds that you can’t hear, so boosting with a peak filter in this range is risky at best. Instead…
2. If you must adjust above 10kHz, use a high shelf filter instead. Cutting is generally less risky than boosting.
3. Don’t try to correct very narrow dips in response. Typically, fixing these will be difficult at best, and force you into unsavory tradeoffs if it requires a significant raise in level.
4. Solve fit issues first before applying any EQ. If you don’t, you’ll wind up overcompensating for bass.
5. You will most often be using peak filters and shelf filters. If you have very well-measuring headphones, it’s conceivable you don’t need EQ, or you’ll only use two shelf filters to meet your tastes.
6. Bluetooth headphones are tougher to equalize than wired headphones. Use very low gain adjustments with this type of headphone to avoid adding distortion.
7. Equalizing speakers is heavily dependent on the room they’re in. You may not be able to get your best results without other changes or treatment.

The above list is by no means exhaustive, but should cover the basics.