Voxengo Span in Ableton Live: How to Reference Tracks Like a Pro


Thales Matos


Voxengo Span is a VST plugin that allows you to reference tracks like a pro in Ableton Live.

I know you want your music to sound flawless, right? Well, today is your lucky day.

Keep reading to learn how to route and operate this spectrum analyzer VST.

Below you'll find a step-by-step tutorial on how to compare your mixes to your favorite songs.

You'll learn to identify problems that would be hard to hear without great speakers and room acoustics.

How Voxengo Span works

voxengo span - vst plugin to reference tracks

This is Voxengo Span's interface.

The blue content shows my song's frequency spectrum.

And the green line is my reference song's spectrum. It's "The Lazy Song" by Bruno Mars.

This shows me how my song's low-end compares to his. It also shows the high-frequency energy levels.

Clearly, my song has more bass. That could be a problem (or not).

But the reference song has more activity in the mid-range, especially at around 200 Hz. That's where they placed the snare.

Besides that, some differences are visible in the high-mids.

And his high-frequency content seems to roll off at a lower frequency than mine.

That's a lot of information, right?

You shouldn't make mixing decisions based on visuals.

However, if you know your room acoustics aren't ideal or don't trust your ears yet, this will help you make decisions more confidently.

How to use Voxengo Span

Here's the thing about Span: it's free.

To fully take advantage of the method you'll learn below, download the VST 2 version.

You will not get the same results if you download the VST 3 version.

Voxengo plugins' user manuals are always super helpful. But not so easy to understand if you're a beginner.

So I'll save you time and headaches. I'll show you a shortcut to the most valuable configuration for referencing tracks with Voxengo Span.

This will ensure your mix will translate well in different speakers and listening environments.

Voxengo Span basic controls, modes, and presets

Voxengo Span shows the frequencies at the bottom and the amplitude on the right side.

Hold Ctrl (on a PC) or Cmd (on a Mac) and click the spectrum. It then isolates the frequencies so you'll listen to that band only.

voxengo span basic commands - band-pass frequency range

This is super useful to quickly figure out which instruments to boost or cut if needed.

Scrolling with the mouse makes it wider or narrower.

If you click Hold, it freezes the graph.

It also has an excellent Mid-Side Stereo preset.

voxengo span mid-side stereo preset

Voxengo Span Default Mode

When you first load Span on a track, it looks like this:

voxengo span - spectrum analyzer - default mode

It displays lots of details and refreshes pretty fast. So on a full mix, it gets confusing.

I like the Default mode when working on individual elements. For example, equalizing a synthesizer or guitar.

There's a high-resolution mode that is even more precise.

voxendo span - spectrum analyzer - high resolution mode

It's the best setting to quickly find the fundamental frequency and tune drum samples.

Voxengo Span in Ableton Live: step-by-step tutorial

Configuring Ableton Live

To compare your mix with a reference track, first load Span in the Master track.

Then create an Audio track for your reference songs. We'll route them to Span later.

It's good practice to compare mixes to more than one reference track. So double-click the reference track and select "Show take lanes."

voxengo span on a reference track - show take lanes

Then load each reference song on a new take lane, all within the same audio track.

reference tracks on take lanes for voxengo span frequency analyzer

This could also be done by grouping lots of audio tracks.

But I prefer using take lanes, so the list of tracks doesn't grow too much.

Important step: change the Output type of the reference track to "External Out" instead of "Master."

reference tracks on take lanes - external output

That way, the reference songs won't get affected by the plugins in the Master Track.

Then align the sections of the songs you want to compare.

reference tracks - aligning choruses

For example, aligning the choruses.

You don't want to compare chorus to verse. The energy levels would be very different in most cases.

Then mute it.

reference tracks - speaker icon - mute track

Now, go back to your Span in the master track. And use the sidechain feature to receive the signal from the reference track.

voxengo span sidechain reference

Ableton Live's routing is done. Let's configure Voxengo Span now.

Configuring Voxengo Span to show two spectra simultaneously

First, there's a lot of information I won't use. So I like to make the visuals cleaner by clicking "Hide Meters and Stats."

voxengo span hide meters and stats

We'll route Voxengo Span to display two spectra at once. It'll overlay the reference spectrum on top of the master spectrum.

This section will be brief, and I'll skip the "whys" because it's just technical stuff. It's how they designed the plugin, alright?

I want you to return to making incredible music and mixes as soon as possible. So here's what you have to do.

Click "routing" on the top to open this menu.

voxengo span ableton live routing settings

In the input routing, add the numbers 3 and 4.

Then, to keep things organized, click "Group names."

Rename group one to MASTER and group two to REFERENCE.


Now at the bottom, you can toggle between the Master spectrum and the Reference spectrum. Let's combine them.

With the Master group selected, click "Underlay" on the top. Select Reference.

voxengo span - two spectra at once - underlay feature

By doing that, Span is going to display both spectra at once.

voxengo span - two spectra - before adjusting settings

But the spectrum is still in high-resolution mode. It refreshes fast and shows too much detail.

Let's make it slower and smoother.

Making Voxengo Span slow and smooth

Click the gear icon to open the settings window.

voxengo span - average, block size, range, offset and smoothening

These are my final settings

Voxengo Span has different kinds of spectrum analysis. My favorite for comparing songs is the Average analysis.

The other modes are helpful too.

But Average is excellent for this task. You just have to let the song play for a few bars, and the plugin will display an average of what's happening.

Otherwise, it would display each transient's frequencies and quickly replace them with the next ones.

That would be confusing and hard to interpret.

This way, you'll be more informed and aware of the bigger picture. Then if you need to change your mix's balance, you will make a better decision.

I like to keep the block size at 8,000.

Larger block sizes mean the spectrum will be more precise in the low-end, at the cost of using more CPU.

Next, it can be beneficial to smoothen the spectrum so you don't worry about each frequency and every detail.

Instead, visualize a broader range of frequencies.

One-third of an octave is a good amount of smoothening.

To work more accurately on a small frequency range, duplicate this plugin and remove the smoothening from the copy.

Offset: reference spectrum loudness matching

Though it's a great feature, I haven't seen people talk about the "Offset" in tutorials.

It makes Voxengo Span align your song's spectrum with the reference track, even if one is much louder than the other.

It removes the loudness factor from the comparison. That's awesome for referencing.

You get to compare your mix to a reference much louder than yours.

And you'll find balance issues because the plugin will display them as if they were equally loud.

So, select "Center" if you want to take advantage of that.

If so, you'll probably have to adjust these two knobs: "Range Low" and "Range High."

Make sure you fit the spectrum within the available space and center it nicely.

Mine is usually between -50 and -25.

Okay, but now the spectrums are different.

Making both spectra look similar

Make sure to switch to the Reference Tab and configure it like you did in the Master Tab.

voxengo span - reference tab - second spectrum

I like to unselect "filled display" in the reference tab. It turns the spectrum into a line that's easier on the eyes.

voxengo span - second spectrum settings - unfilled display

And you can change colors.

Once all this configuration is done, hide the "Groups bar" at the bottom to make the spectrum a bit larger.

voxengo span - hide groups bar

Click this icon in the top right corner and unselect "Show Groups Bar."

Summing to Mono

On a side note, this sidechain analysis only reads one side of the stereo field on your reference track.

So make sure to sum it to mono. Or else the other side's information will not be in the picture.

summing the reference track to mono

And for a super fair comparison, convert your mix to mono too, when referencing.

I usually don't, though. But it's worth mentioning.

Start referencing with Voxengo Span

Finally, Span is ready. That was a lot of configuration, so don't forget to save it.

I saved it inside an Audio Effect Rack to use in all my tracks.

voxengo span template - audio effect rack

To start referencing, loop your song while the reference track is muted. And let it gather information for as many bars as you want.

You can also swap references using your take lanes. Click the speaker icons to compare your mix to different songs.

voxengo span - comparing references - swapping take lanes

Make sure to click on Span to reset the spectrum when you do so.

Best practices when referencing tracks

Voxengo Span offers you lots of information about your song's frequency spectrum.

But don't feel forced to change your mix just because it looks different than your reference.

The goal is not to copy someone else's mix. Nor to make the spectrum have the same exact shape as the reference track.

Every mix has different elements, so these shapes will be different.

If your song is in a different key, it will already look entirely different. The peaks won't align with the reference.

That's why it's essential to use more than one reference track. Ideally, lots of them.

That keeps you from obsessing over details.

Even though Voxengo Span will visually show why your song sounds different than the references, avoid mixing with your eyes.

I know you've probably heard that before.

But it's true, and I've made that mistake.

Always question yourself: does this actually make it sound better? Sometimes it doesn't.

So trust your ears, listen to the reference tracks, and take breaks to reset your hearing fatigue.

Fix the instrument instead of the Master Track

When you find a specific frequency range that needs more energy, avoid the shortcut of equalizing the master track.

Instead, go back to the mix and increase the volume of instruments that operate in that specific range.

And if you think your music sucks after a reference track comparison, read this article.

If you have any questions, ask below.

For more music production guides, visit my website.


Thales Matos

August 31, 2022


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