TUNIC OnlyPure is a professional piano tuning application designed for piano tuners and concert technicians who demand maximum tonal purity, structural clarity, and reliability. The app supports both standard tuning temperaments as well as the original Stopper temperament (B. Stopper, 1988), allowing the tuner to choose the tuning philosophy best suited to the instrument, repertoire, and acoustic environment.

💳 AVAILABLE VERSIONS
Free Demo Version
• Test the tuning engine with full measurement accuracy within one central octave (C4–C5)
• Manual tuning to experience the tuning workflow
• Intended for evaluation purposes only, not for complete piano tunings

Premium Version (Subscription)
• Full keyboard range
• Automatic and chromatic note switching
• Additional temperaments
• No advertisements

🎹 KEY FEATURES (Premium Version)
• No prior measurement of string inharmonicity required
• Immediate start – select A4 pitch and begin tuning
• Automatic compensation of string inharmonicity, stiffness and damping
• Support for standard equal temperaments and Stopper temperament (pure twelfths)
• Outstanding unison purity and exceptional chord clarity
• Multiple instruments can be tuned to the same reference pitch
• Designed for concert halls, studios and professional environments

🎼 STOPPER TEMPERAMENT – PURE TWELFTHS
In addition to standard tuning methods, TUNIC OnlyPure is optimized for the original Stopper temperament, a tuning system based on pure duodecimes (octave + fifth) instead of traditional fifth-based temperaments. This tuning method has been widely used by professional piano and concert technicians in major concert halls worldwide for over 30 years and is valued for its clarity, stability and musical transparency.

🎼 ADDITIONAL TUNING TEMPERAMENTS
TUNIC OnlyPure also fully supports conventional standard temperaments, allowing tuners to work within familiar tuning frameworks when required. This makes the app suitable for: - traditional tuning workflows - comparison between tuning philosophies - repertoire- or venue-specific requirements The tuner can seamlessly switch between tuning modes without changing the overall workflow.

🔊 HARMONIC EQUIVALENT PITCH
Due to string inharmonicity, piano tones do not exhibit an ideal harmonic overtone structure. As a result, the pitch impression of a piano tone differs from that of an ideal harmonic tone with the same fundamental frequency.
TUNIC OnlyPure accounts for this effect by using a harmonic equivalent pitch: a calculated reference pitch corresponding to an ideal harmonic tone that matches the pitch impression of the inharmonic piano tone. This approach ensures consistent tonal relationships and optimal compatibility between piano tones and harmonic instruments.
Consequently, the effective pitch displayed by OnlyPure may differ slightly from the theoretical fundamental frequency. Compared to fundamental-based tuners, deviations of approximately 2–3 cents sharp (typically around 0.8–0.9 Hz at A4) are normal and expected, depending on the instrument’s string properties.

The reference pitch can be manually calibrated if required.

🎯 TARGET AUDIENCE
TUNIC OnlyPure is designed for skilled and experienced piano tuners and concert technicians. Due to its high responsiveness and professional tuning philosophy, the app may be challenging for beginners or occasional users.