Spectral 3D Sound
Spectral 3D Sound is a real-time audio processing mode that gives any track a three-dimensional spatial quality through standard stereo headphones. It works on any track in your library — no special file format required.
Spectral 3D Sound is a Pro feature.
Enabling Spectral 3D
Tap the ≋ Audio Lines icon in the action button row on the Now Playing screen.
[SCREENSHOT: Audio Lines button — normal state vs. active state (purple)]
When active, the button glows purple. The audio character changes immediately — the stereo field opens up and instruments appear to occupy distinct positions around you.
Tap again to disable. The button ignores taps for a couple of seconds after disabling, so the audio has time to stop cleanly before you can re-enable it.
How It Works
Spectral 3D uses a custom audio engine that runs entirely on your device. Here’s what happens when you enable it:
The track’s audio is split into 8 frequency bands, each sent to its own isolated processing chain:
| Band | Frequency | Position in space |
|---|---|---|
| Sub-bass | 60 Hz | Below and behind |
| Bass | 170 Hz | Rear left, low |
| Low-mid | 310 Hz | Hard left |
| Mid | 600 Hz | Front left |
| Upper-mid / vocals | 1 kHz | Directly in front |
| Presence | 3 kHz | Front right |
| High | 6 kHz | Hard right |
| Air | 12 kHz | Above and in front |
Each band is placed at its own position using a model of how sound reaches your ears from that direction in space. Because every band is positioned independently, the frequency ranges don’t smear into each other, which is what gives the effect its clean spatial separation.
Each band is also level-matched, so the result is a tonally balanced image rather than a thin or hollow-sounding effect — placing sound in space would otherwise cost you low end.
All 8 bands start at exactly the same moment, so the track stays phase-coherent from the first sample rather than sounding smeared.
Head Tracking
On AirPods Pro and AirPods Max, the engine uses Apple’s built-in listener head tracking to keep the soundfield anchored in space as you move your head — the 3D image stays in place even when you turn.
On other devices and headphones, it falls back to your device’s own motion sensors, rotating the soundfield in sync with how you physically hold your phone.
Sync
When Spectral 3D is active, Homecrate mutes standard playback and hands the audio entirely to the Spectral engine. Homecrate keeps an eye on the two in the background and quietly realigns them if they ever drift apart — you won’t hear an interruption, and the progress bar stays honest.
Mutual Exclusivity
Spectral 3D Sound and Spatial Audio (the 🌊 Waves button, for recorded spatial mixes) cannot be active at the same time. Enabling one disables the other automatically.
The Equalizer works independently and can be combined with Spectral 3D.
Track Changes
When Spectral 3D is active and the track changes (via skip, queue advance, or Up Next), the engine receives the new file automatically and re-syncs to the new track’s playback position. You don’t need to toggle anything between tracks.
Tips
- Spectral 3D works with any locally stored audio file: FLAC, M4A, MP3, WAV, AIFF.
- It does not work with Plex streaming URLs — download the track locally first.
- The effect is most noticeable on closed-back headphones. Open-back headphones benefit too but the perceived width is subtler.
- Tracks with wide stereo mixes — orchestral recordings, electronic music, studio pop — respond better than mono or very narrow recordings.
- Battery usage increases slightly when active, as 8 parallel audio processing chains run continuously.