BROWSER STROBE TUNER · ULTRA LOW
Ultra-Low Tuner: Tune Down to A-1 (13.75 Hz) Free Online
StroboPro is a free online ultra-low tuner that hears notes down to A-1 at 13.75 Hz. It is a strobe tuner: several harmonics of your note are tracked at once, each shown as its own harmonic ring.
core tuner and preset tuning profiles free · <0.1 ¢ display resolution
What is an ultra-low tuner?
An ultra-low tuner is a tuner built for the very bottom of the audible range and below, where ordinary instrument tuners stop reporting reliably. StroboPro handles this range as a strobe tuner: instead of averaging pitch over time, it compares the phase of your note against a stable internal reference and accumulates the difference. The result is a display you can trust on notes that last many seconds.
The tuning range extends down to A-1 at 13.75 Hz, the lowest note in the bundled Ultra-Low A-1-G4 tuning (the engine's analysis floor is 13 Hz). The tuner tracks several of its harmonics at the same time, each as its own harmonic ring.
Who tunes below 20 Hz?
Most tuners are built for guitar and stop caring below the low E at about 82 Hz. Real music goes much lower:
- 32-foot organ stops. The lowest pipe of a 32-foot rank speaks at about 16 Hz, and it must hold pitch against pipes two octaves higher.
- Sub bass synth patches. Sub oscillators and sine basses often sit at 13 to 30 Hz in electronic, film and game work.
- Extended-range basses. Multi-scale and sub instruments reach below the standard bass guitar range.
- Piano modeling and extended keyboards. Instruments modeled or built below the piano A0 at 27.5 Hz need a tuner that follows them there.
- Sound design. Drone, effect and room-tone work where the fundamental is felt more than heard.
How can a tuner hear A-1 at 13.75 Hz?
First, a tuner does not need to hear a note the way you do. A strobe tuner measures phase: where the waveform is in its cycle, sample after sample. A 13.75 Hz wave is slow, but its phase is just as measurable as a 440 Hz one, as long as the signal is really there in your mic or track.
Second, resolution. Explained without the engineering:
Imagine filming a hummingbird. At normal speed the wings are a blur. Slow the film down and each wing beat becomes distinct. StroboPro does the same thing with samples. At a 48 kHz input, the Ultra-Low A-1-G4 tuning can use a 6 kHz analysis stream. With the same frequency measurement, the frequency steps are now about 2.9 Hz apart instead of about 23.4 Hz apart, which is what makes a 13.75 Hz note resolvable at all.
The Ultra-Low A-1-G4 tuning applies this automatically. It keeps the extra detail for the deepest notes, then shows the harmonic rings that fit safely for the note it finds. You never configure a sample rate or a decimation factor.
A display you can read at any depth
Deep notes are slow, but the display stays alive. StroboPro shows several harmonics of your note at once as independent harmonic rings. Each ring rotates when that harmonic is off pitch and stops moving when it is on pitch. The direction shows sharp or flat and the speed shows how far off it is.
Because every harmonic is tracked independently, you see whether a low note is truly settled or whether its overtones are still drifting, which is exactly the information that matters on long, deep sustains.
Try the ultra-low tuner free
The tuner and the Ultra-Low A-1-G4 tuning (A-1 at 13.75 Hz up to G4) are free on every surface. Pick it from the instrument selector:
- Web: open the Ultra-Low A-1-G4 tuning or tap the button above to start immediately in your browser.
- Mobile: the same tuning and range in the iOS and Android apps.
- DAW: the free StroboPro plugin analyzes your track audio directly, with the same multi-harmonic strobe display.
Related guides
Frequently asked questions
What is the lowest note StroboPro can tune?
The lowest note in the bundled Ultra-Low A-1-G4 tuning is A-1 at 13.75 Hz (the engine's analysis floor is 13 Hz). On the deepest notes, especially below the low E of a bass, the reading takes longer to settle and can wobble by a few cents. Hold the note and let it ring before you tune.
Can humans hear A-1 at 13.75 Hz?
13.75 Hz is below the typical human hearing threshold of about 20 Hz, so you feel it more than you hear it. A strobe tuner can still measure A-1 because it compares the phase of each harmonic against its own reference, not loudness. You do need a microphone or interface that captures the low end honestly.
Do I need special equipment for ultra-low tuning?
No special tuner hardware. Use a microphone or audio interface that passes low frequencies, or skip the microphone entirely with the free StroboPro plugin and analyze a track inside your DAW.
Is the ultra-low tuner free?
Yes. The tuner and the Ultra-Low A-1-G4 tuning are free on the web, on iOS and Android, and in the StroboPro DAW plugin.
Support independent development with Pro
I keep the core StroboPro tuner free. Pro supports ongoing work on Cloud Sync, AI Tuning, and the Piano Tuning Assistant.
Published by Applicaudia, the maker of StroboPro.
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