The basics, explained

In the sense that matters, yes: a booster can genuinely make the audio it plays itself louder, by applying gain before the sound reaches the speaker. What no app on iPhone can do is raise the system volume or make another app such as Spotify louder, because iOS isolates every app's audio.

Open the app, pick a track from your library, and turn the volume dial past 100%. The app applies gain to its own playback in real time, and you can layer a bass boost and equalizer presets on top of that.

No, and no app on iPhone can. iOS gives no app access to another app's audio output. For Spotify specifically, use its own Playback → Volume level setting and choose Loud — that is the real control.

As a marketing figure it is meaningless, because there is no standard that makes "200%" measurable. What is real is gain, expressed in decibels. Past a certain point extra gain produces clipping and distortion rather than more loudness, which is why the app caps how far it goes.

Normal use will not damage modern phone hardware — the output stage is protected and the boost is capped. The real risk is to your hearing: sustained listening above roughly 85 decibels is where damage begins, which is why iOS includes a Headphone Safety limiter.

Yes. There is a dedicated bass dial, plus a 6-band equalizer with bands at 60 Hz, 150 Hz, 400 Hz, 1 kHz, 2.4 kHz and 15 kHz. You can start from a preset and adjust, or reset to flat at any time.

A reliable starting point is +4 dB at 60 Hz, +2 dB at 150 Hz and −2 dB at 400 Hz, leaving the rest near flat. The cut at 400 Hz matters as much as the boosts — clearing the low mids is what makes bass sound defined instead of muddy.

A phone speaker physically cannot reproduce much below about 300–500 Hz, so boosting 60 Hz sends it energy it cannot turn into sound. On the built-in speaker, lift 150–250 Hz instead — that is where the audible impression of warmth actually lives.

Yes. You can speed a track up or slow it down without the pitch shifting, so voices stay natural. It is designed for podcasts, audiobooks and learning a part in a song.

Yes. Whatever output your phone is routed to receives the processed signal. Note that if Reduce Loud Sounds is enabled under Headphone Safety, that ceiling still applies on headphones.

No. Alarms and the ringer are played by iOS itself, and no app can control system audio on iPhone. Those are fixed in Settings — the Ringer and Alerts slider, Attention Aware Features and your Focus modes are the real controls.

iOS 16 or later. There is also an Apple Watch companion for previewing what you have set up.

The app is free to download and free to try. A subscription unlocks unlimited boosting and the full equalizer, and it is what keeps the app ad-free — we do not run ads and we do not sell listening data.

Not yet — an Android version is in development. Worth knowing that the platforms genuinely differ: Android exposes audio effects that can attach to the global output mix, so an Android booster can affect other apps in a way no iOS app can.

Your files are processed locally on your device in real time and are never uploaded, copied or stored by us. The app does use third-party services for analytics, install attribution and subscriptions — those are listed in our privacy policy.