Bass extractor: isolate the bass line from any song in your browser

On most records the bass shares its range with the kick drum, the low end of the guitars and keys, and any synth sub. A low-pass filter cannot separate a bass note from a kick hit in the same octave, which is why "just EQ it" never gives you a bass line you can actually learn from. SplitVocals uses Demucs v4, a hybrid-transformer model trained to recognise the bass instrument — electric, upright or synth — as its own source, and rebuilds it as a separate stream while the kick stays with the drums.

The result is a bass stem you can solo, loop, slow down in any player, or drop into a DAW. The drums, vocals and other stems come from the same pass, and so does the inverse: a bassless mix of everything except the bass.

Bass players learning a song by ear isolate the line to catch ghost notes, slides and the exact rhythm against the kick — the things a full mix hides. Teachers use the isolated part to demonstrate fingering or a walking line, and the bassless mix so a student can play the part themselves over the real band. Producers sample a bass line, or check how a reference track's low end is built before mixing their own. DJs and remixers swap a bass line under a different top, and re-amp a clean stem through their own chain.

Low frequencies are the first thing a low-bitrate MP3 throws away, so the bass stem benefits more than any other from a lossless source — start from a WAV or FLAC when you have one. Modern studio mixes with a clearly recorded bass separate cleanly. The tricky cases are records where the bass and the kick were designed as one sound, such as an 808 in hip-hop or trap: the model splits that sound by what it learned, and some of the sub can land in the drum stem. Heavily distorted bass and synth basses with bright harmonics can also leave part of their tone in the "other" stem.

If a line comes back muddy, listen to the bass and drum stems together, or try the HD Pack and Pro, which run a larger model on a server and add a six-stem split that separates guitar and piano out of "other" as well.

The separation runs inside your browser tab through WebGPU or WebAssembly, so your file is never uploaded and there is nothing to meter — isolate the bass on every song in a set list, not just the one you paid for. The ~170 MB model is downloaded once and cached; after that, separations start immediately, even offline. Chrome and Edge finish a typical song in one to three minutes on the graphics card; Safari and Firefox take a slower CPU path with the same result.