How to Use a Spectrum Analyzer for Mixing

I always preach that you should trust your ears above all else, but sometimes your ears can use an assist. This is why mixing engineers embrace spectrum analyzers – plugins which visually display the frequencies of your audio in real time. Let’s talk everything to know about how to use a spectrum analyzer for mixing.

What is a Spectrum Analyzer

A spectrum analyzer is a tool which measures and reveals the volume versus frequency relationship across the entire frequency range of your track in real time.

A lot of plugins feature a visual representation of your audio’s frequency behavior; this is a spectrum analyzer.

paz spectrum analyzer

Some go into greater detail in showing you information about your audio’s frequency profile than others (which I’ll mention in a moment), but regardless this is an invaluable tool to have alongside simply listening to the audio to know what’s happening.

Why you might ask?

Reasons to Use a Spectrum Analyzer

If the only thing that matters is what your audio SOUNDS like, then why do we want to know what it LOOKS like?

A lot of us don’t have ideal or even quiet spaces to mix in. Speaking of which, I did an overview on where to mix music which covers the best sized room for mixing and how to mitigate room reflections, noises, and outside sounds.

One major advantage of using a spectrum analyzer is that you can see frequency buildups which would be a problem in other listening environments but you can’t hear where you’re mixing.

Alternatively your monitors might not have the frequency response to give you a full picture of your mix aurally speaking. As I covered in my headphones versus speakers comparison, budget monitors are typically lacking in the low end. This can cause you to overcompensate when mixing to the point that when you hear your mix in the car it sounds like a big old boomy mess.

With a spectrum analyzer you can keep these frequencies in check by seeing what you can’t hear.

One bonus reason which is specific to certain spectrum analyzers like the one which comes with my favorite EQ, the FabFilter Pro-Q 3, is you can see frequency conflicts between tracks which you may have missed in listening. I’ll talk more about this as we talk how to use a spectrum analyzer.

How to Use a Spectrum Analyzer

how to use a Spectrum Analyzer

We’ve covered what a spectrum analyzer is and why you might want to use one to this point, now let’s talk how to use a spectrum analyzer.

Frequency Conflicts

One of the best uses of a spectrum analyzer is to identify frequency conflicts between instruments.

As I alluded to earlier, my favorite spectrum analyzer is the one which comes with my favorite EQ plugin, the FabFilter Pro-Q 3.

I did an entire FabFilter Pro-Q 3 review, during which I talked about its analyzer specifically which has a few things which sets it apart from most other spectrum analyzers.

One of these features is the ability to compare frequency profiles between your tracks without having to pull up two tracks (assuming you have an instance of the plugin on both tracks).

As you can see here, the “Collisions” feature shows two or more tracks which have an abundance of volume at a shared frequency range:

fabfilter pro q analyzer

Note that if you don’t have an analyzer which takes other tracks into account, you can simply bring up and compare the spectrum analyzers of two tracks which commonly conflict, such as the kick and bass.

Frequency conflicts between two tracks is one of the leading issues which detracts from a clean mix. Once you know you have a frequency conflict, you can either pan to keep the two tracks separated in the mix (using my audio panning guide), or you can create some complimentary cuts via EQ between them.

In the case of the aforementioned kick and bass which share a fundamental frequency range, you can’t using panning to separate them as they are both best kept centered in the mix. This is where we reach for those complimentary cuts, ideally using sidechaining (see how to sidechain bass to kick).

Phase Issues

A spectrum analyzer can also show phase issues between multiple tracks. Oftentimes you can hear when two acoustic guitars (for instance) are out of phase with one another, but an uncharacteristic weakness in the low end which is a telltale sign of phase issues will reveal itself via the spectrum analyzer.

Comb filtering is a specific phase issue which results in a visually comb-like shape in the frequencies of your audio on your spectrum analyzer.

paz analyzer phase

Many spectrum analyzers like the above pictured PAZ Analyzer from Waves have a separate section which shows potential areas where your audio is out of phase in addition to showing the breakdown of gain distribution across the track or bus’s stereo field.

Frequency Peaks

Perhaps most importantly, spectrum analyzers simply show you which frequencies are strongest (fundamental) and peaking in that specific track or bus.

Placing one on a specific track gives you a visual picture of the fundamental frequency range of that track (where the “body” of that instrument is) as well as its overtones.

This can help you better understand that instrument as well as make EQ decisions alongside what you’re hearing before you’ve put any EQ filters on the track.

A spectrum analyzer can also identify any one off spots of interest where something might be poking out in your tone.

FabFilter’s Pro-Q 3 has hold and freeze features which I showed earlier which highlight the many frequency peaks in your audio. Typically these will just be the aforementioned fundamental and overtone ranges, but sometimes you’ll get a built up in an uncharacteristic section. This can be a result of reflections in the room being picked up, some outside sound, or generally just something which isn’t part of the practical, musical part of your audio.

Being able to easily see this peak saves you time from having to sweep around to find something which doesn’t sound right. You can quickly see the frequency, solo it to hear if it’s something which shouldn’t be there, then make a cut right there within the plugin accordingly.

Mix Comparisons

A sneaky good use of spectrum analyzers is to apply one to a commercial mix that you like to get a visual representation of the frequency breakdown.

Oftentimes it helps and you might be surprised to see that there’s not nearly as much low end in one of your favorite mixes than you thought.

This goes back to the idea that the space which you mix in can be deceiving, so this visual context can help to recalibrate your mind as you listen to that mix as well as your own.

Of course using reference tracks is one of my top and most important evergreen mixing tips, because it keeps your ears focused on the task at hand and keeps you from mixing in a vacuum.

If you want to be REALLY sneaky, you can use a match EQ plugin which is essentially a spectrum analyzer with the added ability of applying the frequency profile of one track to another.

So if you’ve got a reference track you want your mix to sound like, instead of getting an idea of the changes you might need to apply to your mix based on looking at its frequency profile or listening to it, you can actually nudge your entire mix in that direction using this kind of macro EQ adjuster.

It’s best used conservatively, but sometimes this feature (which is included with FabFilter Pro-Q 3) is that final master bus touch that you need (I actually included this as part of my master bus tutorial.

Do You Need a Spectrum Analyzer

Overall, spectrum analyzers certainly aren’t necessary in mixing, but they can be huge time savers in helping you locate problem frequencies.

They can also act as invaluable educational tools in helping you better understand the audio in your mix or a commercial mix you aspire to sound like.

Of course it bears worth repeating, don’t use a spectrum analyzer in place of your ears, and always trust your ears above all else when mixing.

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