chapterpass
Audible's ACX has eight technical checkpoints, and a file that misses one comes straight back. chapterpass masters each chapter file to spec: RMS loudness between -23 and -18 dBFS, peaks held below -3 dBFS, a noise floor under -60 dBFS RMS, room tone at the head and tail, and a 192 kbps CBR MP3 on the way out. Every output is verified against the full spec before download, and you see the measured value next to the requirement for each checkpoint. The processing runs in your browser through WebAssembly, so your audio never leaves your device. There is no account to create. Your first file is free, then $36 per finished hour, $27 from 5 hours, $18 from 10 hours, billed by the second. A free measurement page at /free-acx-check reads your loudness, peak, noise floor and silence padding against the spec without mastering anything. chapterpass masters the measurable technical specs. It does not edit your recording, remove noise, or fix narration.
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AudioMaster
AudioMaster is an intuitive app designed for musicians and podcasters to instantly enhance their audio recordings. By importing your audio, you can immediately experience a boost in volume and an overall polish of the mix. The app offers genre-specific equalizer settings, including options for podcasts, rock, folk, blues, classical, country, hip hop, electronic, jazz, Latin, new age, pop, R&B, and soul, allowing users to tailor the mastering process to their specific needs. Available on iPhone, iPad, Mac Desktop, and Android platforms, AudioMaster enables users to export, save, and share their mastered audio effortlessly. The app is part of Future Moments' suite of mobile apps for content creation, which includes tools like MicSwap, AudioFix, and VideoMaster.
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Acon Digital Mastering Suite
Acon Digital Mastering Suite consists of five plug-ins for audio mastering that were designed for ultimate signal transparency: Dynamics is a combined compressor, expander or gate. The look-ahead can be set anywhere from 0 to 30 milliseconds and the intelligent algorithm ensures a band-limited gain signal which reduces potential distortion to a minimum even with minimal attack and release times. You can use up to 4 times oversampling to further reduce distortion. Multiband Dynamics is the multiband extension of Dynamics which allows dynamic processing in up to four separate bands. You can freely set the cross-over frequencies and even the filter slopes can be set freely in the range 6 and 48 dB per octave. Limit is a transparent limiter with intelligent look-ahead in the range 0 to 30 milliseconds that reduces distortion to a minimum.
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Moozix
Moozix is an AI stem mixing and mastering platform for musicians who want to hear their song finished without building a mix from scratch. Upload stems, a rough mix, or one full audio file, and Moozix creates a private mix and master preview so you can hear the transformation before exporting final files.
Moozix is built for artists, producers, and home studio creators working with vocals, drums, bass, guitars, beats, instruments, or AI-generated music. It can help balance levels, shape EQ, control dynamics, improve stereo width, manage loudness, and move the track toward a more polished release-ready sound.
Unlike mastering-only tools, Moozix is designed for songs that may still need mixing decisions before the final master. Users can work from multitrack stems when they have them, or start from a full song file when they need a simpler path. Pro exports can include a 24-bit WAV master, MP3 preview, premaster mix, and processed stems for continued work in a DAW.
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