About

This tool utilizes the Web Audio API to manipulate the frequency response of digital audio files within the client browser. It targets the sub-bass and bass regions (20 Hz to 250 Hz) using a Low-Shelf Filter, allowing for significant gain adjustments without affecting the structural integrity of higher frequencies. Accuracy in signal processing is maintained via floating-point arithmetic in the audio buffer.

Unlike simple volume increasers, this architecture includes a Dynamics Compressor Node at the end of the signal chain. This acts as a limiter, attenuating peaks that exceed 0 dBFS (Decibels relative to Full Scale) to prevent digital clipping and distortion. The export function uses an OfflineAudioContext to render the processed signal faster than real-time, ensuring the downloaded file matches the playback configuration exactly.

Formulas

The gain in decibels (dB) relates to the amplitude ratio via the logarithmic scale. When adjusting the bass slider, the amplitude modification A follows:

LdB = 20 ⋅ log10(VoutVin)

For the Biquad Filter (Low Shelf), the transfer function H(s) in the s-plane is approximated digitally. The cutoff frequency fc is set to 200 Hz. The compressor threshold is typically set just below 0 dB:

if Signal > Threshold → Gain ↓ by ratio R

Reference Data

Frequency Band	Range (Hz)	Musical Characteristics	Effect of Boosting
Sub-Bass	20 - 60	Felt rather than heard. Kick drum fundamentals, sub-synths.	Adds power and physical sensation. Too much causes flabbiness.
Bass	60 - 250	Rhythm section fundamentals. Bass guitar, lower piano notes.	Adds fatness and warmth. Over-boosting creates mud.
Low Mids	250 - 500	Body of acoustic instruments. Human voice fundamentals.	Adds resonance. Can sound boxy if uncontrolled.
Mids	500 - 2000	Attack of percussion, rhythm guitar, vocals.	Increases presence. Can cause listener fatigue (honky).
Upper Mids	2000 - 4000	Attack of drums, lead guitar lines. High sensitivity area for ears.	Adds bite and intelligibility. Risk of harshness.
Presence	4000 - 6000	Clarity and definition of instruments.	Brings sounds to the front of the mix.
Brilliance	6000 - 20000	Harmonics, cymbals, air, hiss.	Adds sparkle and air. Too much emphasizes sibilance.

Frequently Asked Questions

Distortion occurs when the amplitude of the digital signal exceeds 0 dBFS. While this tool includes a limiter to compress peaks, extreme gain settings (e.g., +15dB) can still flatten the waveform significantly, creating audible artifacts or "pumping" effects. Use moderate adjustments.

Yes. The browser's AudioContext can decode most standard audio formats supported by the underlying operating system, including MP3, WAV, and often FLAC. The processing is done on the uncompressed PCM data.

Real-time playback is subject to system interrupts and CPU load. The OfflineAudioContext renders the audio as fast as possible in a separate thread, calculating every sample mathematically without dropping frames. This results in a mathematically perfect WAV file relative to the settings provided.

The export sample rate defaults to the sample rate of the source audio file or the browser's context rate (typically 44.1 kHz or 48 kHz). This avoids unnecessary resampling artifacts during the process.