Bass Booster

Give a song, a phone recording or a video's soundtrack more low end. The bass booster lifts everything below the chosen frequency with a smooth low-shelf filter, from a light +4 dB to an extreme +18 dB or a custom value, and can add an extra lift around 50 Hz for sub bass. Because more bass also means higher peaks, a limiter (or a lower overall volume) keeps the result from clipping. Files are processed in your browser and never uploaded.

How to use this tool

1. Choose one or more audio files.
2. Pick a boost: Medium (+8 dB) suits most music; Strong and Extreme are for small speakers or effect.
3. Set the bass frequency (100 Hz by default) and, if you like, the extra sub-bass lift.
4. Keep the limiter on, choose MP3 or WAV and press Calculate.

Formula

Low shelf (Web Audio / Audio EQ Cookbook): A = 10^(gain ÷ 40), ω₀ = 2π × f ÷ sample rate, slope S = 1

Below the shelf frequency the gain approaches the boost (in dB), above it the gain returns to 0 dB; at the frequency itself it is half the boost. The optional sub-bass lift is a peaking filter at 50 Hz (Q 1.2) of half the boost, at most +6 dB. If the boosted audio would peak above −1 dBFS, the limiter lowers just those moments (5 ms look-ahead); "Lower the whole track" scales everything down instead. MP3 output is decoded again to make sure the encoder did not push peaks over full scale.

Example

With +8 dB at 100 Hz, a 50 Hz kick drum gets about +7.5 dB louder, the 100 Hz range +4 dB, and a voice at 400 Hz is nearly unchanged. If a kick drum already peaks at −2 dBFS, lifting it by 7.5 dB would take it to about +5.5 dBFS, so the limiter turns those moments down to −1 dBFS.