Why bass boosts distort
Bass notes carry a lot of energy. When you raise them by 8 or 10 decibels, the waveform grows tall enough to exceed the maximum level a digital file can hold, and the extra is chopped off. Clipping creates harsh harmonics that sound like crackle. Most files are already mastered close to full scale, which leaves no room. Boosting cleanly means making room first.
Know your frequency ranges
Sub-bass is roughly 20 to 60 Hz, the rumble you feel in a chest. Bass is 60 to 250 Hz, where kick drums and bass guitars live. Low mids from 250 to 500 Hz give body, and too much there sounds boxy. A boost centred at 60 Hz adds weight on headphones and subwoofers. Around 100 Hz it adds punch audible on laptops. Around 160 Hz it adds warmth to voices and guitars. Choose the region you want instead of lifting everything.
Leave headroom before you boost
Lower the level of the track a few decibels before boosting, by about half of the amount of the boost. Then raise the bass. After boosting, check the peak. If it exceeds the ceiling, reduce the gain again or use a limiter, which squashes only the loudest peaks. The bass booster tool applies these steps for you: it reduces the level, adds a limiter, and lowers any remaining peak at export.
Cut the sub you cannot hear
Energy below about 30 Hz is inaudible on nearly all systems, yet it uses headroom and can make speakers rattle. A high-pass filter at around 28 Hz removes it. The result is a tighter low end that can be played louder without distortion.
Make bass audible on small speakers
Phone and laptop speakers cannot reproduce notes below roughly 100 Hz, so a plain boost does little. The ear can still perceive a missing fundamental when it hears the harmonics, the overtones at two and three times the frequency. Harmonic bass adds those overtones with gentle saturation. It is the reason many tiny speakers sound like they have bass. If you listen on headphones, leave it off to keep the low end clean.
Check on more than one system
Listen on headphones, a laptop, and a phone before you settle. If the bass disappears on the phone, add harmonics. If it overwhelms on headphones, lower the amount. Take breaks, because ears adapt to bass quickly and you may add too much. A boost of 4 to 8 dB is typical. Compare with the original at equal volume using the A/B switch.
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