Home Recording Basics: Low-End Mixing for Bass Guitars, Synths, and Samples

Last week’s installment of our Home Recording Basics covered how to mix a drum kit. Next, we’re laying down the rest of the mix's foundation with the bass.

Nothing is better than that big, fat bottom-end that makes you want to dance. All of the power in a track comes from the bass frequencies — the boom that makes your trunk rattle, the thud you feel in your chest. But when mixed improperly, it can leave a track feeling bloated and muddy or even weak and thin.

Whether it’s a funky bass groove, a pulsing synth line, or a thunderous 808, we’re here to get the cops called at your next party with these tips and tricks for mixing bass guitars, synths, and samples.

Author’s Note: The most important thing about mixing low-end is doing it in a controlled environment. Bass frequencies are some of the hardest to tame, and it’s very easy to get tricked by your room. Before attempting to mix the low-end, make sure you set up your monitors correctly and treat your room.

Balance

Volume-wise, the level of the bass varies greatly from genre to genre. Hip-hop and dance tracks tend to be more bass-heavy, while rock songs tend to favor the drums and guitars. Pop usually falls somewhere in between.

Remember, bass frequencies are felt more than they’re heard, and — importantly — the perception of bass frequencies varies greatly for the listener, depending on how quietly or loudly they’re listening to the song.

Bass frequencies are felt more than they’re heard, and the perception of bass frequencies varies greatly for the listener, depending on how quietly or loudly they’re listening to the song."

According to equal-loudness contours (a concept sometimes referred to as “Fletcher-Munson curves," after pioneering sound researchers Harvey Fletcher and Wilden Munson), bass frequencies require higher decibel levels in order to be perceived as the same volume of midrange and treble frequencies, especially at quieter overall volumes.

Make sure your bass signal has enough volume in the low-end, as well as enough character in the midrange to cut through the mix.

One trick engineers use to achieve a nice balance is to “mult" their bass. Multing means splitting a signal into multiple channels. Some engineers create “low" and “high" mults, allowing you to process the different frequency ranges separately.

As far as panning, bass is almost always panned in the center. Some genres use wide stereo bass signals, but it’s the high frequencies creating the illusion of width, not the low-end. Scientifically, our ears have a hard time distinguishing what direction low frequencies are coming from. Plus, leaving your bass in the center makes it feel more important.

EQ

A lot of engineers make the mistake of thinking bass is all about the low-end. Obviously, the bass and sub-bass frequencies are important, but there’s more to it than that.

Rolling off all the high-end from the bass cuts out all of the attack, often leaving tracks feeling dark, muddy, and boomy. The key is balance between multiple bands.

Remember, most people listen to music on their phones and laptops. They don’t have a set of studio monitors and a subwoofer like you do. If the bass doesn’t have some presence (upper midrange frequencies), you literally won’t even hear it on your phone.

It’s important to note that the kick drum and bass both tend to occupy the same frequency range. To keep them from fighting, try giving each instrument their own space in the mix.

If you’re using a sub-heavy kick sample, let the bass sit above it in the low-mid range. If you have a powerful bass line, let the kick live in the low-mids.

Bass Guitars

On a standard, 4-string bass guitar, the lowest note played (E1) has a fundamental frequency of 41Hz. The fundamental of the highest note depends on how many frets are on the neck but is generally in the 311-400Hz range. (A 20-fret bass will have its highest fundamental at around 311Hz, while a 24-fret will have its at 392Hz.)

Some engineers use a high-pass filter to remove frequencies below 40Hz since the bass doesn’t produce any fundamentals there. However, the low B-string common on 5- and 6-string basses has a low fundamental of 31Hz, so be careful when recording and mixing these instruments.

  • Bottom: 40Hz – 80Hz (too much is boomy)
  • Attack / Pluck: 700Hz – 1.5kHz
  • Snap: 2.5kHz – 5kHz

Bass Synths

You can make a synth sound like just about anything. Every synth patch is different — just try to identify which frequency ranges are adding to the part and which are causing problems.

  • Sub: 20Hz – 100Hz
  • Bass: 100Hz – 250Hz
  • Low-Mids: 250Hz – 700Hz
  • Mids: 700Hz – 3kHz
  • High-Mids: 3kHz – 7kHz
  • Highs: 7kHz+

Samples

Samples can produce notes with fundamentals as low as 20Hz. It’s highly recommended that you tune your samples to the key of the song.

  • Bottom: 20Hz – 100Hz (too much is boomy)
  • Fatness: 100Hz – 250Hz (too much is muddy)
  • Snap: 2.5kHz – 5kHz

Compression

Compression is great. It helps to control dynamics, it makes an instrument jump out of the speakers. It puts stuff in your face, but it can also suck the life out your bass.

For this reason, many modern compressors include a high-pass filter (HPF) on the detection circuit. This allows you to set an HPF to, say, an 80Hz threshold—then, everything below 80Hz will pass through the compressor unaffected, while everything above will be compressed. This can be a particularly useful tool when you want to add attack without sacrificing sustain.

Some engineers choose not to compress the low-end at all. Simply turn the level of the bass signal up until it just barely starts pushing on your bus compressor. Then, set the levels of the other instruments to fit accordingly. The other instruments will be compressed, while the bass will retain its full dynamic thunder.

Other engineers choose to absolutely slam their bass signals. The low-end needs some consistency to convey power, and many engineers achieve that with aggressive compression. Ratios of 8:1, 12:1 and even ∞:1 are often used to knock off 6dB or more of the original signal to keep bass tracks consistent.

If you’re still struggling to balance the attack and sustain, try using parallel compression on the bass. This lets you control the attack and release separately.

Alternatively, you could use multi-band compressors on the bass. Use slower attack and release times to increase sustain on the low-end, and faster speeds on the midrange to increase attack.

If you’re trying to reduce sustain, try using a noise-gate with a slow release to fade out in time with the track.

If the kick and bass still aren’t playing nicely together, many engineers use sidechain compression. This causes the bass to be compressed whenever the kick hits, leaving a little more space for the kick to punch through.

Effects Processing

For the most part, low-end and time-based effects like reverb and delay don’t mix. Such effects often just muddy up bass frequencies.

To help create width and depth for bass instruments, you can try adding reverb or delay to just the midrange and treble frequencies, while rolling off the effects on the low-end."

However, to help create width and depth for bass instruments, you can try adding reverb or delay to just the midrange and treble frequencies, while rolling off the effects on the low-end. This allows the percussive elements (the aforementioned attack and slap) to reverberate without sacrificing the clarity and impact of the bottom-end.

One of the best effects to use on bass is distortion. Doesn’t matter how you get it — tape, tube, plug-in, guitar pedal, etc. You can apply it directly to the channel or in parallel for added depth and character.

Distortion and saturation add harmonics to a bass signal, which let it cut through a mix. It’s also a great way to ensure your 808 shows up on phone and laptop speakers.

Chasing Your Tail

Now that you’ve got the bass sounding right, make sure it isn’t causing any problems with the drums. Maybe the bass sustains for too long and masks some of the drum hits. Or maybe the drums overpower the bass in the chorus.

Whatever the issue, spend some time chasing your tail, correcting any problems your problem-solving caused. Once your kick and bass sit together nicely, with plenty of impact in the lows and character in the mids and highs, you’re ready to start bringing up the other instruments.


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