8 Reasons For Thin Mixes & How To Fix Them

Thin mixes are something all mix engineers have likely struggled with at some point. Sometimes a mix needs a bit of extra care and processing to get filled out. Other times, we're actively mixing in ways that thin out the mix unknowingly. Regardless of where you're coming from, if you're looking to solve your issue of thin mixes, you've come to the right place!

Let's discuss these reasons in greater detail throughout this article and investigate a few strategies to fix each issue. Before we get started, though, let's consider how we can tell whether our mix is thin or not.

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How To Tell If Your Mix Is Thin

A thin mix lacks substance, particularly in the low-end and low-midrange frequency bands. That is to say, it lacks strong frequency content below about 250 (bass) and between 250 – 500 Hz (low-mids).

We can naturally tell whether a mix sounds thin simply by listening to it. However, the extent of a mix's thinness can be more difficult to determine, especially with ear fatigue, loudness bias, and other psychoacoustic trickery.

It's important to have proper monitoring that gives us an accurate representation of the mix. This means monitors and headphones with flat frequency responses and maybe even a subwoofer to cover the low end. It also means proper room acoustic and acoustic treatment when monitoring through studio monitors.

If we can't hear our mix accurately, we'll have a more difficult time finding and addressing issues of thinness and more.

Another important tool for understanding issues of thinness in our mixes is the use of reference mixes.

A reference mix (or reference track) is an audio mix/track that we can compare our work against as we make our way through the mixing process. A reference track is typically in the same style/genre as what we're working on and acts as a goal post to work toward in terms of mix aesthetic.

By A/Bing our mix against a reference, we can get quick feedback as to whether our mix is fuller or thinner. If we've chosen a reference mix that's decently full (but not “muddy”) and our mix sounds thin in comparison, we'll likely have to make some adjustments to increase the fullness in our mix.

I have a video going into detail regarding reference mixes. Check it out here:

With that, let's get to the reasons why mixes may sound thin and what to do about them.

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Lack Of Low-End Frequencies

If a mix lacks low-end energy, chances are it'll sound thin. That is unless the song arrangement itself is lacking in low-end elements (bass guitar, synth bass, kick drum, 808s, tuba, timpani, etc.).

For most modern mixes, though, there will be some amount of musical information in the low end that should be well-defined in the mix. If these frequencies aren't well-represented in a mix when there are significant elements producing them, it's likely the mix will sound a bit on the thin side.

Before moving on to solving issues of lack of low-end, I should mention that an over-represented low-end is no good either, as these long-wavelength frequencies demand lots of power to be heard and can quickly eat up headroom and lead to a lopsided mix.

With that, let's get to some solutions.

How To Fix A Lack Of Low-End Frequencies

The most obvious way to bring up the low end of a mix is to increase the gain/volume of the low-end elements (think kick drum, bass guitar, bass synth). This can help reduce the thinness of the mix by solidifying the low frequencies.

At the same time, we shouldn't go too far in increasing these levels either, as having too much low-end information will quickly eat up headroom and lead to a lopsided, bass-heavy mix.

Rather than increasing the gain/volume of a bass track within the mix, we can also opt to boost the low-end frequencies with EQ. Again, we should be careful here, as going too far will cause more harm than good.

In fact, if the bass elements are lacking presence but are well-represented in the low-end frequencies, boosting the track or the low-end with EQ won't help nearly as much as boosting in the midrange. We're naturally much more sensitive to midrange frequencies, so if our bass elements lack presence even after settling the thinness issue in the low end, we can opt to utilize saturation and/or EQ to help bring out their midrange presence in the mix.

Another useful technique that I recommend for nearly every mix is to filter out the low-end frequencies from any tracks that don't have musical information down there. Many times, the low end only contains noise, which is best removed.

This may seem counter-intuitive, but cleaning out the low-end noise and only keeping the musical information actually enhances the overall clarity and level of the low end. In doing so, we eliminate potential phase issues and panning (if the low-end “noise” happens to be in panned tracks). Each of these aspects helps improve the low end to mitigate the thinning of the mix.

Use a high-pass filter for this and adjust it to taste. Of course, every mix is different, but I'd advise setting the HPF cutoff a good amount below the lowest fundamental to avoid phase shifting in the track audio. That is unless that track is competing too much with the low-end or low-mids, where high-passing it above its fundamentals may be a more appropriate choice (common with guitars).

On the topic of phase, it's also important to maintain strong phase relationships if we want a strong mix in the low-end and low-mids. This is particularly true of transient information (the initial attack of percussion and other instruments).

Aligning the phase of the tracks with significant low and low-mid information is worthwhile to reduce thinning in the mix. Nudge the tracks' audio so that the positive portions align as much as possible with the other positive portions and the negative portions align as much as possible with the other negative portions.

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Insufficient Arrangement

One potential reason for a thin mix is a thin arrangement. Songs written with thin instruments and recorded with few tracks will often suffer from a thin overall sound.

Fortunately, many styles popular styles with only a few instruments (acoustic guitar and vocals or piano and vocals, for example) contain harmonically rich sources (acoustic guitar, vocals and piano all have wide ranges with good harmonic content).

Therefore, it's often not a big deal for the style. However, there's no denying that when done properly, a singer-songwriter's song (just acoustic guitar and vocals) will sound fuller than a full band's. That said, it's on us as mixing engineers to bring this fullness to fruition.

How To Fix Insufficient Arrangements

The obvious way to fix an insufficient song arrangement is to add more to the arrangement. This isn't always possible if we're not producing the song ourselves. If we're only concerned with mixing, we'll have to find other ways to improve a thin arrangement.

We could double up tracks by recording overdubs, duplicating the track and affecting the copies differently, or with parallel processing.

If recording overdubs is out of the question, try duplicating a track and processing the copy differently. When done tastefully, this can thicken the track and the overall mix. However, if we cause too many phase issues between the two (or more copies), we can do more harm than good in terms of mix thinness.

A few strategies here include:

• Pitching one copy a few cents up or down relative to the original (use multiple duplicates if need be).
• EQing the copies differently.
• Shifting the timing of one copy relative to the other.
• Panning the copies differently (be sure to check for mono compatibility by summing the mix to mono and listening for cancellation, which can worsen the thinness of the mix).

Instead of (or perhaps in addition to) duplicating a track for thickness, we can also utilize parallel compression. Sending a track or multiple tracks to an auxiliary return and processing the parallel channel with compression, saturation, or other effects can help to thicken the sound and the overall mix.

I discuss how to use effects sends/returns and the benefits of doing so in this YouTube video:

We can also use these processes (notably compression and saturation) to process tracks by themselves. By compressing the dynamic range and adding harmonic saturation, we can effectively reduce the thinness of a track and the mix at large.

Finally, I should mention the use of time-based effects (delay and reverb) to enhance the dimensionality of an otherwise thin arrangement. Sometimes adding spaciousness to the mix with these effects is all we really need to alleviate the perceived thinness of the mix.

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Phase Issues

Phase issues are liable to cause thinning in a mix because out-of-phase audio signals cancel each other out due to destructive interference.

Phase is the position of a point in time on a wave cycle, though, in mixing, it refers to the alignment of positive and negative amplitudes between non-identical waveforms. Having “better phase” means better alignment and less destructive interference between tracks, yielding better mix results.

Of course, we're typically not dealing with simple waveforms when mixing. However, the idea of phase still holds up when we take into account the sum of all positive and negative amplitudes of all tracks at any given point in time. If there's significant phase cancellation between the low-end and low-mid frequencies, we'll end up with a thinning of the mix.

In contrast, having good phase coherence between our tracks allows them to work together and produce a full low-end and low midrange in the mix.

I have a video dedicated to the importance of proper phase relationships between tracks in a mix. You can check it out here:

How To Fix Phase Issues

I already touched on phase issues in the section on fixing a lack of low-end, but I'll go into more detail here.

Phase issues affect low frequencies more than high frequencies due largely to the longer wavelengths. They can also have a devastating effect on transients if they're particularly bad.

So it's worth nudging the tracks of low-end and transient-heavy elements so that their phase/polarity is as aligned as possible. That way, we can optimize each track to work together at positive and negative polarity and minimize the phase cancellation experienced in the mix.

If a track is nearly completely out of phase, we may consider flipping its polarity (with a polarity flip or “phase flip” switch) to align its phase rather than nudging it in the timeline.

It's also worth considering the frequency-dependent phase-shifting side effect of EQ. Although it's usually not an issue, having overly steep boosts, cuts, or filters can cause phase shift at and around the corner/cutoff or centre frequencies (depending on the filter type).

If phase issues are a concern, you can always meter with a phase correlation meter. On these meters, +1 means the stereo channels are identical, -1 means they're completely opposite, and 0 means “maximum width,” although we'll generally want the correlation to be closer to +1 for better phase.

Additionally, we can sum the mix to mono to check for phase cancellation between the two stereo channels.

Mono compatibility is important even beyond fixing thin mixes. I discuss mono compatibility more in this video:

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Poor EQ Choices

Poor EQ choices (as is the case with bad mixing in general) will lead to several issues in the mix, including, of course, thinning. This is especially true if we're cutting too much and causing too much phase shifting with steep roll-offs.

Cutting too much from the important tracks in the low-end and low-mids can cause thinning.

However, perhaps counter-intuitively, we can actually enhance the clarity and fullness of these ranges by cutting these same frequencies from those tracks that do not offer any musical information in the low-end and low-mids. Noise, rumble, electromagnetic interferences, etc., can all be cut from the tracks that don't have anything musical to add in the low end.

We may be tempted to reduce the “muddiness” of the mix by cutting in the 200-500 Hz range. This is effective since there's a lot of fundamental frequency energy build-up in this low-mid frequency band.

However, when we cut too much in the low-mid, we go too far and end up with a thin mix rather than a muddy one.

Another common mistake is in trying to eliminate resonances from a track's audio.

This is typically done with what I call the “parametric sweeping technique,” which takes a parametric EQ, boosts a narrow band (6 dB or more is a good starting point), and sweeps the band across the frequency spectrum. As the resonant frequency is boosted even more by the EQ, it will really poke its ugly head through the mix. Once found, we can adjust the gain of the EQ band to the negative and notch the frequency from the signal.

However, we can get caught up trying to find offensive frequencies for the sake of it. Boosting a narrow band of parametric EQ and sweeping it across the spectrum will make every boosted frequency sound bad.

Cutting too many “resonant” frequencies will lead to a comb-like EQ curve with unnatural notches and phase shifting across the frequency spectrum. This type of EQ curve is unlikely to sound great and will likely contribute to the thinning of the mix if there are significant cuts in the lows and low mids.

How To Fix Poor EQ Choices

Avoiding poor EQ choices begins with developing a strong sense of the purpose of EQ, which ultimately stems from the purpose of mixing: to achieve a proper balance between the tracks of the session.

In terms of the balance of levels, faders are our primary tools. EQ, in a way, can be thought of as frequency-dependent fader control. In fact, graphic EQs are just that.

In understanding this basic concept, we can better utilize EQ to achieve balance and avoid creating thin, weak mixes.

Another critical strategy for better EQ decisions is to EQ in the context of the mix rather than EQing tracks individually in solo. The mix is rarely about any single track but rather about how all the tracks work together.

However, when it comes to EQing each track in the context of the mix, things can get a bit tricky. I will usually start with a specific group of tracks (all the drum tracks, for example) or, alternatively, with the mix's most “important” tracks.

I advise putting together a hierarchy of mix elements, listing every track in order of importance or “presence” in the mix. Then it'll be easier to know which track to give preferential EQ treatment, especially when it comes to filling the lows and low-mids appropriately to avoid a thin mix.

And, as always, I'd advise to always A/B test any EQ moves by toggling the EQ on and off. If the EQ benefits the mix, move on. If it doesn't, try adjusting the parameters so that it does. If that doesn't work, perhaps EQ isn't right for the mix, and there will be other ways to reduce the thinness of the mix.

I have a video where I share my top 11 equalization techniques. Check it out here:

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Not Using Compression

Compression is one of the most important processes in mixing, and while it's not always necessary depending on the mix, it can help to add a sense of fullness and weight to an otherwise thin mix.

Dynamic range compression effectively reduces (compresses) the dynamic range of a signal by attenuating the loudest portions while keeping the quieter portions alone.

By reducing the dynamic range, we can ultimately increase the average level (with appropriate makeup gain) and have a thicker, fuller sound as a result.

How To Fix A Lack Of Compression

The obvious way to make up for a lack of compression that could contribute to a thin mix is to use more compression in the mix.

Compression aids in balancing a mix by acting as a sort of automatic gain control. If a signal level exceeds a set threshold, the compressor reduces its gain. As the signal drops below the threshold, the compressor disengages.

In addition to its role in balancing, compression also thickens the sound as it reduces its dynamic range. Although it's often felt subtly, this compression can help reduce the thinness of certain tracks and, therefore, the entire mix.

Glue compression brings elements together in a mix to sound more cohesive at the expense of reduced separation. If we're dealing with thin arrangements and mixes, separation may not be a major concern, and glue compression can help us reduce the overall thinness.

Glue compression is achieved with bus compression, whether on the mix bus or the subgroup buses. In setting a single compressor to control the dynamics of multiple signals routed together, we get this bonding of the specific elements within the bus.

I talk about the concept of glue in more detail in this video.

Starting with a mix bus compressor, moving onto subgroup/bus compression, and finally getting to individual track compression (if need be) is part of top-down mixing.

In addition to the actual dynamic range compression, many compressors will colour the sound by adding their own subtle distortion. Some of this colouration can help fill in and enhance the frequencies in the thin regions of the mix.

As always, be sure to A/B any compressor settings with proper level matching (use makeup gain) so that you can be sure that the compression is actually helping the mix.

I have a video where I share my top 11 compression techniques. Check it out here:

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Not Using Saturation/Distortion

While distortion is often frowned upon in audio, there are actually “good” and “bad” types of distortion we should be aware of. Clipping, for example, is often considered bad, whereas saturation and overdrive are often cherished for their effect in mixing.

Harmonic saturation is a style of distortion that effectively combines soft-knee/program-dependent compression with harmonic generation. It produces new harmonics and enhances pre-existing harmonics in a signal in a sonically pleasing way.

Saturation occurs naturally due to the nonlinearity of analog equipment (even if only slightly), particularly in tubes, tape, transformers and transistors. It is also achievable digitally with plugin effects.

Saturation can help to thicken up thin-sounding tracks and subgroups, and even sounds great on the mix bus in some instances.

How To Fix A Lack Of Saturation/Distortion

If we can rewind to the recording stage and get our hands on some quality analog equipment, we can achieve saturation by simply driving the gear a bit hot on the way in.

Otherwise, we can use plugins that properly emulate analog hardware and drive them a bit harder than “0 VU” (roughly -20 to -18 dBFS) to get a bit of that emulated saturation.

There are also dedicated saturation and distortion effects we can utilize to add harmonic distortion and soft-knee compression to our signals and thicken them up to avoid thin-sounding tracks and mixes.

When setting up saturation or distortion to address mix thinness, subtlety is often the key. We typically don't want to drive our signals to the effect of overdrive/distortion. Rather, we want to subtly thicken them up to combat our thin-sounding mix.

Instead of (or in addition to) saturating individual tracks or buses, we can also utilize parallel saturation. This way, we can keep the original signal intact while getting a grittier colour on the effects return. We can then mix the two channels together to achieve the colouration and thickening we need for the mix at hand.

I have a video discussing parallel processing in greater detail if you're interested in checking it out:

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Not Using Time-Based Effects

Time-based effects (delay and reverb) are the primary tools for creating a sense of space in the mix. Adding dimensionality with these effects can potentially help thicken up the midrange (and even the low end if necessary) to reduce the thinness of the mix.

By adding width and depth with the artificial reflections of delay and reverb, we can bring more sonic information into the mix and achieve the effect of thickening up otherwise thin tracks.

How To Fix A Lack Of Time-Based Effects

The first strategy I have for you regarding time-based effects is to nearly always set them up on their own effects return channels. Send individual tracks to an auxiliary track and have the reverb or delay inserted on that auxiliary track rather than directly on the individual tracks themselves.

By utilizing auxiliary returns, we can have much more independent control over these time-based effects, which is nearly always a great thing.

One big advantage of doing so is that we have independent fader control for each effect return channel.

Once our effects returns are set up, we should dial in the parameters. Focus on the delay time and feedback/repeats parameters for delay effects and reverb time and size parameters for reverb effects to get a sense of the effect and then move on to the more intricate controls to fill out the mix.

Pay special attention to the width produced by reverb and delay, and double-check the mix in mono to listen for phase issues.

Furthermore, we can EQ the effects to fit them better into the mix and to help reduce clutter in the low end while still filling out the bands that require it.

We can also compress and/or saturate them to thicken them up a bit further in the mix.

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Overly Wide Stereo Image

In the last section, we briefly discussed how stereo width could fill out the perceived balance of the mix and lead to less thinning.

However, stereo width can have the opposite effect when pushed too far, causing the mix to become even thinner. This is largely due to the fact that the “stereoness” or stereo width of a mix is dependent on the differences between the left and right channels. These differences (in phase) will cause the directionality we want in stereo, but they'll also cancel each other out.

As we discussed in the phase issues section, this can be a major detriment in the midrange.

So, pushing a mix too wide can cause severe phase issues between the left and right channels, ultimately leading to weak, thin mixes.

How To Fix An Overly Wide Stereo Image

In order to avoid an overly wide stereo image that would thin out the mix, we must maintain a strong centre image. That means keeping some things relatively centred and not pushing too many elements to the side (hard left and hard right).

Avoid overdoing hard panning and driving stereo imaging plugins too wide, either. In most cases, keeping the most important elements in the centre/mono will work in your favour to maintain a strong centre image and reduce any thinning of the mix. Bass elements with lots of low-end energy should also be panned in the centre, though their midrange information can be spread if it serves the mix.

Try LCR (left centre right) panning if the mix calls for it. This is a panning strategy where we can only pan hard left, centre/mono or hard right. This strategy forces us to decide what elements are to be panned mono. Keeping these elements mono can help alleviate mix thinning, especially when the mix is summed to mono.

With that, I should once again reiterate the importance of mono compatibility and periodically monitoring in mono for the best results. I'll also remind you that phase correlation meters can be invaluable in these situations.

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Related Questions

Why does my mix sound muffled, and how can I fix it? Muffled-sounding mixes are often caused by a lack of high-end energy and over-represented low-end energy, along with poor transient definition and dynamics. Overdoing or incorrect use of compression, EQ, limiting, distortion and time-based effects can contribute to a muffled mix. Fix these issues, and you'll achieve clearer, cleaner mixes.

Why does my mix sound distorted, and how can I fix it? Distorted recordings often cause distorted mixes. However, distortion can also arise at the mix stage, where digital clipping (exceeding 0 dBFS), the over-representation of harsh high-end frequencies, overcompression, over-limiting, and, of course, distortion effects, can also cause the mix to distort and sound distorted. Address these issues to reduce distortion in your mix.