A shelf filter uniformly boosts or cuts all frequencies above (highshelf) or below (lowshelf) a cutoff point. Unlike parametric filters (which affect a narrow band), the shelf affects the entire spectrum from that point onward. It is the type of EQ found in guitar amplifiers and home stereo systems — simple and effective for broad tonal adjustments.
Bass & Treble Booster
Adjust bass and treble of your audio with BiquadFilter shelf filters and real-time preview.
What bass and treble filters are and how they work
Bass and treble are the extremes of the audible frequency spectrum. Bass lives below ~250 Hz (kick, bass guitar, male vocal body), treble above ~3 kHz (vocal presence, harmonics, brightness). This tool uses BiquadFilter nodes of type lowshelf (for bass) and highshelf (for treble), processed by the Web Audio API with OfflineAudioContext — the same audio engine used by modern browsers. Processing happens locally with no data sent to the server, and the preview uses debounce to prevent stuttering while adjusting sliders.
Adjust, listen to the preview, and export
- Upload your audio file. The waveform is displayed for reference.
- Move the bass and treble sliders (-15 to +15 dB). The preview updates automatically after you stop adjusting.
- Listen to the preview, confirm the result, and export in your chosen format.
Sources and references for this tool
These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
- BiquadFilterNode — Web APIsMDN Web Docs — BiquadFilterNode reference including the lowshelf and highshelf filter types used in this tool.
- OfflineAudioContext — Web APIsMDN Web Docs — Interface for offline audio rendering — used to apply EQ without real-time playback.
- Audio EQ Cookbook — Digital FiltersZolzer / W3C reference — Mathematical reference for biquad filter coefficients including shelf filters.