639 Hz · Patent-Protected · US 11,836,330
Retune Your Music To 639 Hz
The frequency of connection, repair, and shared rooms.
See it work
See 639 Player Plus retune music in real time
Sixty seconds. Real-time 639 Hz retune of a song you'll recognise.
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Why 639 Player Plus
Built for people who own their music — and want to hear it differently.
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Heart-Chakra Tone
The fourth solfeggio frequency — traditionally associated with the heart, with relationships, and with communication.
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Shared Spaces
A common pick for music played in shared rooms — kitchens, dinners, workplaces with people in them.
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Patent-Protected Retune
Real-time conversion of your existing library, US Patent 11,836,330.
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No Tracking, No Ads
One-time $19.99 per platform. No subscriptions, no listening telemetry, no upsells.
How it works
Real-time retuning. No re-encoding. No quality loss.
We don't make copies of your songs. We don't apply equalization or compression. We shift the pitch of the audio stream as it plays — and that's the entire trick.
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Add your music
Point 639 Player Plus at a folder on your device — MP3, FLAC, WAV and most other common formats are supported. Your files stay where they are; nothing is uploaded.
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Tap to retune
One tap and the entire library plays at 639 Hz. The original files aren't touched — the retune happens in real time on the way to your headphones.
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A/B as you go
Switch back to 440 Hz any time. Compare the same song side-by-side and decide for yourself. Set a sleep timer, build playlists, listen offline.
Why we built 639 Player Plus
639 Hz is the fourth tone of the canonical solfeggio hexachord — the *Fa* of the medieval Italian scale — and in modern sound healing tradition it's the heart-chakra tone, associated with connection, relationships, communication, and the music we play in shared rooms.
It's a tone you put on when other people are present. Where 528 Hz tends to feel internal and personal, 639 Hz feels relational — kitchens with family, dinners with friends, workspaces with colleagues, any room where the music you choose is also the music other people will hear. Sound healers describe 639 Hz as a tone for relationship work and harmonization; in everyday practice many listeners simply find it the easiest of the solfeggio frequencies to play around other people without anyone noticing the retune.
We built 639 Player Plus for the same reason we built every Player Plus app: getting your music to a specific frequency, in real time, without re-encoding or quality loss, shouldn't require a digital audio workstation. Point the app at your library. Pick 639 Hz. Listen.
The retune is patent-protected (US 11,836,330), real-time, and lossless. Original files stay untouched. Switch back to 440 with one tap. Bulk-add an album. Set a sleep timer. Listen offline.
Pricing matches the rest of the line. Free for twenty retunes, no card, no signup. After that, $19.99 unlocks 639 Hz on your platform forever, or $99.99 unlocks all ten solfeggio frequencies. No subscriptions. No ads. No tracking. We don't sell your listening data because we don't collect it.
Built and self-funded by SYQEL INC. We answer to users, not investors. The frequency-shifting capability is patent-protected so no third party can revoke your access to it. Use 639 Hz wherever shared spaces and shared sound matter to you.
From the audience
Loved by listeners who own their music.
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"I keep 639 Hz on during family dinners. The kids haven't noticed but everyone seems calmer. I'm here for it."
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"Switched my whole household onto 639. Conversations feel slightly easier. Could be coincidence — taking it anyway."
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"Solid app, well-designed, no nonsense. The kind of build quality you don't see from indie devs often."
Get the app
Try free. Upgrade once.
No ads. No tracking. No subscriptions. 14-day money-back guarantee on every paid tier.
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Free trial
$0
20 retunes. No card. Just open the app and try it.
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Unlock 639 Hz
$19.99
One-time. 639 Hz unlocked forever on this platform. Add other frequencies later for $19.99 each.
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Unlock all 10
$99.99
One-time. 639 Hz plus all 9 solfeggio tunings (174, 285, 396, 417, 528, 639, 741, 852, 963).
Prefer a direct installer? Windows .exe · Mac .dmg
Patent-protected by US Patent 11,836,330 · Built and self-funded by SYQEL INC
FAQ
Quick questions
What is 639 Hz used for?
In the solfeggio tradition, 639 Hz is associated with the heart chakra and with connection — relationships, communication, harmonization, repair work in shared spaces. Sound healers use it in partner meditations and group sessions. In everyday listening, many people choose 639 Hz when music is part of a shared environment — kitchens, dinners, workspaces with other people — because it tends to hold its quality without drawing attention.
What does 639 Hz do?
In the solfeggio tradition, 639 Hz is the heart-chakra tone — paired with connection work, partner meditations, and any setting where music is shared. Whether you experience anything specific is your own to discover. Technically, 639 Player Plus retunes your music in real time so the note D#5 sits at 639 Hz, with A4 landing around 451.74 Hz, without altering the original files.
How is 639 Hz different from 528 Hz?
Both are middle-range solfeggio tones. 528 Hz tends to feel internal and personal — many people gravitate to it for solo meditation. 639 Hz feels relational — many people gravitate to it when music is part of a shared room. Practitioners often use 528 Hz for inner work and 639 Hz for connection-focused or shared-space sessions.
Can I play 639 Hz music in a shared space?
Absolutely — that's one of the reasons people choose it. 639 Hz tends to be the most "company-friendly" of the solfeggio set; the retune is subtle enough that guests typically don't notice anything different about the music, and many find the result quietly more inviting.
Is it a one-time purchase?
Try it free for 20 retunes, then $19.99 unlocks this frequency permanently. Want all 10? $99.99 one-time. No subscriptions, ads, or tracking.
The other tunings
Looking for a different frequency?
We make a player for each tuning so you can pick the one that fits what you're after. Every app uses the same patent-protected real-time engine.