Bass Booster

How to boost the bass of a song or recording

Three steps, in your browser.

1. 1

   Drop the file

   A song, a music bed or a voice recording: MP3, M4A, WAV, FLAC and other common formats up to 100 MB and 30 minutes.

2. 2

   Pick a preset and listen

   Start with Light, Medium or Heavy, or set the frequency and the boost yourself. Press play and switch between Original and Boosted while it plays; every slider move is heard at once, and both sides play at the same loudness.

3. 3

   Process and download

   The whole file is filtered with the browser's own audio engine, lowered as a whole if the boost would clip, and saved as an MP3 at the bitrate you choose or as a 16-bit WAV. The page tells you the peak and how much it lowered.

What the bass booster does

• A low-shelf filter for the bass

  A low-shelf filter lifts everything below a frequency by the same amount and leaves the rest alone. You choose the frequency, 60 to 250 Hz, and the boost, up to 18 dB. The presets use 100 Hz, where bass guitars, kick drums and the body of a voice sit.

• Audio equalizer online

  Turn on the 5-band equalizer to shape the rest: 60 Hz, 250 Hz, 1 kHz, 4 kHz and 12 kHz, each up or down by 12 dB. Cutting a little at 250 Hz often clears boom that a bass boost brings out; a lift at 4 kHz brings words forward again.

• No clipping

  Adding bass adds level. If the loudest moment would go past the top of the scale and distort, the page lowers the whole file just enough to keep the peak at -1 dB, and tells you by how much. That is why a boosted file can sound a little quieter.

• A fair before and after

  Louder always sounds better at first, so the player plays the original and the boosted version at the same loudness by default. What you hear is the change in tone. Turn Match loudness off to hear the file as it will be saved.

When a bass boost helps

• A thin phone recording

  Phone microphones and small rooms can make a voice sound thin. A light boost around 120 to 150 Hz gives it back some body; heavy settings make speech boomy rather than clearer.

• Laptop and phone speakers

  Small speakers cannot reproduce the deepest bass, so a boost at 60 Hz is mostly heard on headphones. For playback on a laptop, set the frequency higher, around 150 to 200 Hz, where those speakers still respond.

• A music bed for a video

  A background track that sounds weak under a voice-over often needs a few dB below 100 Hz. Keep the boost moderate so the music does not cover the voice.

• Car audio

  Cars add road noise in the low end, so a song can sound flat on the road. Medium is a good start; listen at the volume you drive with and turn the playback down if the bass becomes uncomfortable.

The presets

Each preset is a low-shelf filter at 100 Hz. Its effect at two frequencies, computed with the Web Audio filter formulas:

Bass boost, equalizer or volume?