Bass, mids, treble. Adjusted and baked in.

At a glance

What the three bands actually do

Bass is a low shelf at 200 Hz, meaning everything below that point is raised or lowered together. This is where kick drum, bass guitar and the weight of a voice live. Boosting it adds body; cutting it removes rumble and the boominess of a room.

Mids is a peaking filter centred at 1.2 kHz with a fairly wide Q. This is the region the ear is most sensitive to, and it is where the intelligibility of speech sits. Boosting brings a voice forward; cutting pushes it back and is a common trick for making a backing track sit under narration.

Treble is a high shelf at 3.5 kHz. Consonants, cymbals, string detail and air. Boosting adds clarity and presence; cutting reduces harshness and sibilance.

The adjustments are applied with the browser's own filter implementations and baked permanently into the output file — this is not a playback setting that only works here. A make-up gain is applied automatically in proportion to the largest boost, so a heavy bass lift does not clip.

When you'd want this

• Making a quiet, muffled recording intelligible — the voice clarity preset cuts the low end and lifts the mids and treble, which is usually the whole fix.
• Bass boosting music for headphones or a car system that is light in the low end.
• Preparing narration or a podcast, where thinning the low end stops the voice sounding boomy and muddy. Pair it with the podcast prep tool for levelling and encoding.
• Fixing a recording made too close to the microphone, where proximity effect has exaggerated the bass — cut the low shelf a few dB.
• Deliberate effects, like the telephone preset, which cuts both extremes to leave the narrow band a phone line passes.

Using it well

Cut before you boost. It is a mixing cliché because it is true: if a recording sounds muddy, cutting the low mids usually works better than boosting the treble, and it does not eat headroom. The result sounds cleaner and stays further from clipping.

Small moves. Three decibels is a clearly audible change. Six is a large one. Twelve is a special effect. The sliders go to ±12 because occasionally you want that, but most useful adjustments are in the ±2 to ±5 range.

Leave normalise on unless you are matching this file to others that you are levelling separately. EQ changes the peak level of a file, so without it you will find the result quieter or louder than the original for no reason you intended.

If the recording has a hum or hiss underneath, EQ is the wrong tool — cutting the bass to remove a 50 Hz buzz also removes the bottom of the voice. Noise reduction targets it properly.

What you lose

Headroom, when you boost. Raising a band raises the peak level, and the automatic make-up gain compensates by pulling the whole file down — which means a heavy boost trades overall level for the shape you asked for. That is why cutting is often the better move.

Reversibility. The EQ is baked into the output file. Boosting the treble and then changing your mind is not the same as putting it back — you are now applying a cut to already-boosted audio, and the two do not perfectly cancel. Keep the original.

A generation of quality, on lossy output, as with any re-encode. Use WAV if the file is going into a DAW, where you would rather do the EQ there anyway.