If you've spent any time mixing or producing, you probably have a decent understanding of EQ. If not, it's a basic tool we use to adjust the balance of frequency content in an audio signal. It's one of the most important parts of any great mix, as it controls how every element interacts.

However, not all EQs are created equal. While they may look similar on the surface, different types of EQs behave differently under the hood, particularly when it comes to how they affect phase.

Phase (which you can learn more about here ) refers to the timing relationship between frequencies in a signal. Traditional EQs can subtly shift this timing as they process audio. Most often, this isn't an issue. However, in certain situations, problems like comb filtering or phase distortion can arise.

That's why we sometimes use linear phase EQ. It's designed to preserve phase relationships across all frequencies, offering a unique solution for when precision is critical.

Let’s take a closer look, so you can start using linear phase EQ in your mixes the right way.

What is Phase?

Before we get into the weeds, let's talk more about phase.

When two or more signals are combined, their phase determines how they interact. This could mean that they reinforce each other (constructive interference) or cancel out (destructive interference). This relationship is especially important when you're dealing with multi-miked recordings, stacked vocals, or layered instruments.

EQ plays a surprising role in phase.

Traditional equalizers, which we could refer to as minimum phase EQs , not only adjust amplitude but also shift the phase of frequencies as they’re boosted or cut. This shift can be subtle, but it does change the timing of different frequency components. Too much, and you might start running into some of the issues we talked about earlier.

To visualize this, imagine two identical sine waves. When they’re perfectly aligned, they double in amplitude. But if one is delayed slightly (a phase shift), their peaks and troughs no longer line up. The audible result is either slight distortion or a reduction in the level of the sound. Now imagine EQing a snare in two separate tracks. If you get different phase shifts in each, you can end up with a hollow or weak combined sound.

How Does Linear Phase EQ Come Into Play?

Linear phase EQ is unique in that it doesn't alter the phase relationships when you cut or boost frequency content.

In other words, all frequency components of the signal are delayed equally, which keeps their alignment intact. This is achieved through a digital signal processing technique called FIR (Finite Impulse Response) filtering.

FIR filters work by analyzing a portion of the signal in advance, which essentially creates a look-ahead buffer. By applying symmetrical filters that affect both past and future parts of the waveform equally, they make sure all frequencies arrive at the same time, preserving their phase relationships.

This differs from minimum phase EQs, which apply asymmetric filters that alter the phase of each frequency differently. Minimum phase filters prioritize real-time performance and analog-style behavior but come at the cost of potential phase distortion.

With linear phase EQ, the phase remains “linear," meaning it doesn’t change across the frequency spectrum. This is what makes it such a powerful tool for audio engineers who want to use EQ without affecting its spatial characteristics or risking phase-related artifacts in the mix.

Pros and Cons of Linear Phase EQ

Pros:

• Phase coherence: Maintains perfect timing between all frequency components.
• Transparency: Great for mastering, vocal stacks, and other phase-sensitive scenarios.
• Precision: Allows for detailed tonal shaping without introducing coloration.

Cons:

• Latency: Requires lookahead buffering, which makes it unsuitable for live performance or real-time monitoring.
• Pre-ringing: Can introduce a subtle echo before transients, especially in percussive material.
• CPU usage: More demanding on your system compared to traditional EQs.

I like to think of linear phase EQ as a surgical tool.

When used in the right context, such as mastering or parallel processing, which we'll get into in a bit, it can yield incredibly clean and professional results. But like any precision tool, it should be used deliberately and with awareness of its trade-offs.

When to Use Linear Phase EQ

So, as you've probably guessed by now, linear phase EQ isn’t always the best tool for the job. However, there are specific scenarios where its unique capabilities shine.

Mastering

By the time a song gets to the mastering stage, tracks are already balanced and panned across the stereo field. Applying EQ at this stage with a traditional (minimum phase) EQ can introduce unwanted phase shifts between elements that are otherwise in perfect alignment.

Linear phase EQ eliminates that risk for mastering engineers, so they can make transparent, broad or narrow EQ changes across a full mix without coloring the sound or damaging the stereo image. This is especially important when making small adjustments that affect multiple instruments at once.

Parallel Processing

When you're blending a dry (unprocessed) signal with an EQ’d version, like you might do with parallel compression or saturation, it's important to have good phase alignment.

Minimum phase EQs can shift frequencies just enough to cause comb filtering or phase cancellation when the signals are summed. Linear phase EQ prevents this by keeping the phase relationships intact between both versions of the signal, giving you a clearer, more cohesive sound.

Precision Tasks

I like to use linear phase EQ whenever I need to do any surgical EQ. This can include getting rid of nasty resonances in vocals, taming harshness, or cleaning up muddiness with a narrow Q factor.

With linear phase EQ, you can make precise cuts without introducing additional coloration or phase anomalies, which can be especially noticeable in high-definition or exposed audio.

Multiband Compression with EQ

While I'm a huge fan of multiband compression, it's one of those processors that can do more harm than good when used improperly.

Multiband compressors work by splitting the frequency spectrum into multiple bands using crossover filters. This band-splitting happens before any compression takes place, even if the compressor isn’t actively reducing gain. Even inserting a multiband compressor into your chain can alter your signal.

These crossover filters, especially in traditional multiband compressors, can introduce subtle phase shifts, time delays, or resonances, which can hurt your audio fidelity.

Some multiband compressors use linear phase filters, which prevent additional phase distortion from compounding these issues. Linear phase filters maintain phase alignment, so that your EQ adjustments don't interfere with the already phase-sensitive behavior of the multiband processing.

When NOT to Use Linear Phase EQ

By now, it's probably pretty clear how powerful linear phase EQ can be. That doesn't necessarily mean it's always the right tool for the job, however. In fact, there are many situations where using it could actually make things worse.

Real-Time Scenarios

Linear phase EQ introduces latency because it processes audio using lookahead buffers. This delay makes it a poor choice for real-time applications like live performances, tracking, or monitoring during recording.

You’ll notice a lag between your input and what you hear, which could be enough to throw off your timing or feel.

Drums & Percussion

While linear phase EQ can be helpful for multi-mic drum tracks, one of the main drawbacks is that it can introduce pre-ringing. This is a subtle but often unpleasant “echo” that occurs just before a transient hit. It can smear the attack of drums, snares, and other percussive instruments, making them feel less punchy or natural.

If you're working on transient-heavy material, I recommend using a regular EQ.

If You Want Coloration

Not all phase shifts are bad.

In fact, many analog-modeled EQs rely on non-linear phase behavior to add character and warmth. If you want a particular tone or some coloration with your EQ, linear phase EQ might not be your cup of tea, as it tends to sound very clean. Sometimes a little imperfection sounds better.

CPU Concerns

Linear phase processing requires more computational power than regular EQ, so if you're running a large session with tons of plugins and virtual instruments, adding multiple linear phase EQs can be taxing on your system.

Unless you absolutely need an ultra-precise EQ, it’s often more efficient to use traditional EQs during the mixing phase and reserve linear phase tools for mastering or final touches.

A Deeper Look at Pre-Ringing

As I said, pre-ringing is one of the major downsides of linear phase EQ.

Because linear phase EQ plugins work by analyzing the audio both forward and backward in time using FIR (Finite Impulse Response) filters, it offers perfect phase alignment.

However, the trade-off is that little unnatural “echo” that appears before a transient hit, which is caused by the filter’s lookahead nature.

Basically, the processor anticipates the transient and adjusts in advance, creating a ghost-like smear that precedes the actual sound.

It's most noticeable on sounds with sharp attacks, like snares or kicks, and it can make them sound less punchy or smeared.

Now, if you're using a linear phase EQ for a mellower sustained source, such as a pad, ambient texture, or a vocal, you might not notice the pre-ringing effect at all. Since these sounds don’t rely on fast transients, the ringing before the note is barely perceptible.

My Favorite Linear Phase EQ Plugins

Now that you have a better understanding of linear phase EQ, let's take a look at some of the best linear phase equalizers on the market!

FabFilter Pro-Q3

FabFilter Pro-Q 3 has been my go-to EQ for a few years now. I'd go as far as saying that it's probably one of the top five most respected EQ plugins in the industry. It offers both minimum and linear phase modes with a sleek, intuitive interface.

In linear phase mode, you get control over latency settings (Zero Latency, Natural Phase, Linear Phase – Low/Medium/High), which makes it easy to balance between CPU load and ultra-precise processing.

Plus, with adjustable phase mode per band, an ultra-smooth GUI with a real-time spectrum analyzer, and mid/side processing with dynamic EQ capabilities, it's one of the most versatile EQs out there.

Waves Linear Phase EQ

Waves’ Linear Phase EQ was one of the first mainstream linear phase plugins. It focuses exclusively on linear phase processing, with five filter types and high-resolution spectrum displays.

While it might not look as pretty as FabFilter's linear phase EQ, it's just as excellent for mastering and corrective EQ. I know plenty of great mastering engineers who use it when they need a transparent EQ to make subtle tonal adjustments. It’s great for classical music, film scoring, and pretty much any genre where having the highest fidelity is key.

DMG Audio EQuality

DMG Audio’s EQuality is great because you can throw it on every track and still have CPU to spare. It’s got everything, including linear, analogue, and minimum phase modes for serious flexibility, plus six bands with deep control over Q, gain, and frequency.

The interface is also super intuitive, and with M/S processing, spectrum analysis, and auto-listen mode, it's an incredibly user-friendly linear phase EQ.

Blue Cat Liny EQ

Blue Cat’s Liny EQ is a rock-solid choice if you want a clean, precise EQ that doesn't mess up your phase relationships. It has impressively low latency (under 3ms), which is rare for this type of plugin.

You get eight bands, multiple filter shapes, and ±40dB of gain range. It’s surprisingly flexible for a graphic-style EQ. The real-time spectrum analyzer and spectrogram make it easy to dial in surgical changes, and the mid/side and dual-channel options open up stereo shaping possibilities.

Plus, this linear phase EQ barely touches on your CPU and adapts beautifully to any workflow.

Final Thoughts - Should You Use Linear Phase EQ?

Linear phase EQs are powerful, but they’re not always the best tool for the job.

Their main strength lies in the way that they preserve phase relationships. In fact, it's exactly what makes them so ideal for mastering, parallel processing, or any situation where phase shifts could cause issues.

However, as I noted, that level of precision often comes with trade-offs like added latency or pre-ringing artifacts. These drawbacks can be super problematic in real-time applications or on transient-heavy material.

At the end of the day, mixing is all about using the right tool for the job. Don’t reach for a linear phase EQ just because it sounds fancy. Reach for it when the mix actually calls for it.

Here's my best piece of advice to leave you with: try it. Run your mix through different EQ types, A/B your changes, and listen closely. Your ears are the final judge. Trust them and you'll be good to go!