Free Bass Boost for MP3, WAV and FLAC Files

What a bass booster changes in a song

A bass booster makes the low frequencies of a song louder compared with everything else. You choose two things, the frequency in hertz (Hz) below which the boost applies, and the amount in decibels (dB). A boost of +6 dB doubles the strength of the signal in that range, and about +10 dB is what most listeners hear as twice as loud.

A shelf boost lifts the whole range below the chosen frequency by the same amount, with a gentle slope around the frequency itself. That keeps the boost natural, because the kick drum, the bass line and the low notes of the piano all rise together.

A peak, or bell, boost on an equalizer works differently. It raises a narrow band around one frequency and leaves the frequencies on either side alone. Producers use it to bring out one thing, such as the thump of a kick drum, and a shelf when they want the whole bottom end bigger. The guide to equalization covers both filter shapes in detail.

Bass frequencies and what lives in each range

The frequency slider runs from 40 to 250 Hz and starts at 100 Hz. Where you set it decides which part of the low end gets louder. A low setting adds rumble and weight, and a high setting adds body and warmth along with some of the lower mids.

A shelf at 100 Hz still raises 50 Hz and 60 Hz, because everything below the setting goes up. Moving the frequency higher widens the boosted range, and moving it lower narrows it to the deepest notes.

Finding the right frequency by ear

If you are not sure where the bass of a song sits, exaggerate first. Set the boost to 12 dB or more and preview the song at 60, 100 and 150 Hz in turn. The setting that makes the bass line or the kick drum jump out the most is where its energy lives.

Keep that frequency and bring the amount back down to Light or Medium for the file you download.

How much boost to add

Start with less than you think you need. The ear gets used to a heavier low end within a minute, and a boost that sounds right in the first chorus can be tiring by the end of the song.

The amount also changes the overall level of the download. A mastered song already peaks close to 0 dBFS, so almost any boost would push it over. The booster then turns the whole file down until the loudest point sits at −1 dBFS. The bigger the boost, the more the vocals and the rest of the mix drop, and the quieter the file sounds next to the original at the same volume setting.

Starting points by style of music

Different styles carry their low end in different places. These settings are a first try to adjust by ear.

That level drop is what keeps the download clean, and turning up the player makes up for it. To compare the boosted file with the original fairly, match their loudness first. The LUFS meter measures both, and the difference in LUFS (loudness units relative to full scale) tells you how far to turn one of them up.

Matching the boost to headphones, cars and phone speakers

The same file sounds very different on different speakers, so set the boost for the place you will listen most.

• Headphones and earbuds with a good seal reproduce deep bass well. Light or Medium at 60–100 Hz is usually enough, and higher amounts at a loud volume become tiring quickly.
• Car systems tend to sound bass-heavy already, because a small, closed cabin reinforces low frequencies. Start with Light and a low frequency, then add more only if the bass still feels thin on the road.
• Phone and laptop speakers are too small to move much air below about 100 Hz. A boost at 50 Hz changes little there. Set the frequency to 120–150 Hz so the boost lands where the speaker can play it.
• Subwoofers and club systems handle the lowest range. A boost at 40–60 Hz is where they make the biggest difference.

Listening level matters too. Human hearing is less sensitive to low frequencies at low volume, a curve known as equal loudness, or Fletcher–Munson after the researchers who first measured it. A song played quietly seems to lose its bass, and a small boost brings it back. Played loud, the same boost can sound excessive.

Fixing muddy, boomy or distorted bass

Most problems with a bass-boosted song come from the frequency setting or from a second boost stacked on top of the first.

• Muddy, with vocals hard to follow. The shelf frequency is too high and is lifting the low mids. Move it down toward 80–100 Hz and keep the same amount.
• Boomy, with notes that ring on. The boost is too strong for the room or the speaker. Lower it by 3–4 dB, or move the frequency down so it hits the deep range only.
• Distortion or rattling during playback. The file itself does not clip, so the distortion comes from the speaker running out of travel or from the player adding its own bass on top. Switch off the phone or app equalizer and lower the volume.
• No difference on a phone. The speaker cannot play the boosted range. Raise the frequency to 120–150 Hz, or listen on headphones.
• Quieter than the original. The boost was turned down to stay below clipping. Turn up the player, or use a smaller boost if you need the file to stay loud.

Avoid boosting a file that has already been boosted. Each pass makes the whole song quieter and the bass heavier, and the second round tends to cross into mud. Go back to the original and choose a stronger setting.

Bass boost in Spotify and on your phone

The booster works on audio files you have on your device. Streamed songs cannot be loaded into it, but most streaming apps and phones have an equalizer of their own.

In Spotify on a phone, tap your profile picture, then Settings and privacy, then Playback, turn on Equalizer and choose a preset or drag the low-frequency points up. On desktop, the Equalizer switch sits under Playback in Settings. Spotify does not change audio settings while it plays on another device through Spotify Connect.

On Android, Spotify uses the phone’s built-in equalizer when there is one, so a change there also affects other apps. An equalizer in an app only changes how songs sound on that device. A boosted file keeps its bass on every player and speaker you send it to.

Shaping bass in your own mix

A shelf boost works on a finished song as a whole. In a mix, where the bass and drums are separate tracks, producers have more precise tools.

• Compression evens out the level of the bass so every note sits at the same weight. The BC-1 Bass Compressor adapts its settings to a bass signal.
• Saturation adds harmonics, higher frequencies that let the ear hear a bass note on speakers too small to play its fundamental. The guide to saturation explains how it works.
• A bass multi-effect such as LANDR FX Bass combines EQ, compression and drive voiced for bass and 808s in one plugin.
• A different bass sound is sometimes the real answer. A sampled electric bass such as Sonic Bass Pro can replace a weak part altogether.

For a wider choice of bass instruments and processors, see the best bass plugins.

What the downloaded WAV contains

The download is a WAV file at 16-bit, 44.1 kHz, stereo, the format of an audio CD. Any phone, computer, car stereo with USB playback or video editor opens it without conversion. It takes about 10 MB per minute, around ten times the size of a typical MP3.

To share the boosted song as an MP3, convert the WAV in an audio editor and pick a high bitrate, such as 256 or 320 kbps. Low bitrates save space by removing detail, and the deep bass and the cymbals are often where you hear that first.

Keep the original song as well. If the boost turns out too strong on a new speaker, start again from the source and choose a lighter setting.