Shruti Box Online: Sa, Pa and Ma Drone
A shruti box holds the drone that Indian singers tune to: Sa, usually with Pa, sounding without a break. This shruti box online opens on C♯ (1½ kattai, black 1) with Sa and Pa in a reed-like tone, so you can press Play and start your riyaz. Choose any scale from C to B, swap Pa for Ma, add the lower Sa and set the volume so the drone sits just under your voice.
Kattai, harmonium key and Sa frequency
Sa in the third octave at A4 = 440 Hz; the same names apply to every octave.
| Sa | Kattai | Harmonium key | Hz |
|---|---|---|---|
| C3 | 1 | white 1 | 130.81 |
| C♯3 | 1½ | black 1 | 138.59 |
| D3 | 2 | white 2 | 146.83 |
| D♯3 | 2½ | black 2 | 155.56 |
| E3 | 3 | white 3 | 164.81 |
| F3 | 4 | white 4 | 174.61 |
| F♯3 | 4½ | black 3 | 185.00 |
| G3 | 5 | white 5 | 196.00 |
| G♯3 | 5½ | black 4 | 207.65 |
| A3 | 6 | white 6 | 220.00 |
| A♯3 | 6½ | black 5 | 233.08 |
| B3 | 7 | white 7 | 246.94 |
How to use it
- Press Play with the volume low, then raise it until the drone is just under your voice.
- Tap one of the common Sa notes, or pick any Sa with Note and Octave under Settings; the line under the frequency shows its kattai and its white/black key number.
- In Settings, keep add Pa (fifth) for Sa–Pa, or tick Ma instead of Pa for ragas that leave out Pa; add lower Sa for a deeper drone.
- Choose a tone there too: Shruti box is reed-like, Tanpura is brighter, Sine and Triangle are softer for headphones.
- Sing Sa and hold it until it blends with the drone, then move on to your alankars. Esc or Stop ends the sound.
Help and explanations
Everything is synthesized in your browser: there is no recording of a real box, nothing to download and nothing sent anywhere. Like an electronic shruti box, it keeps a steady pitch for as long as you need, and where the browser allows it the screen stays on while it plays.
Shruti box for riyaz: what the drone does
A drone is a fixed reference: when your voice drifts sharp or flat, the beating against Sa makes it audible at once, and Pa frames the octave so you always know where the middle of your scale is. That is why riyaz usually starts with a long, quiet Sa against the drone, then Pa, then upper Sa, before any sargam or composition. Hold each note until the sound is smooth, rest, and repeat; the timer under the note shows how long the session has been running.
Carnatic and Hindustani singers use the same drone; only the names of the swaras change (Ri and Da in Carnatic, Re and Dha in Hindustani). Sa–Pa suits most ragas. For ragas without Pa, such as Malkauns, singers tune the drone to Sa and Ma; tick Ma instead of Pa and the second reed moves to Ma. Pa and Ma are tuned as pure intervals above Sa (3:2 and 4:3). If you want to see how close your sung Sa is, open the voice tuner in another tab while the drone plays.
Choosing your shruti by voice: kattai and white/black numbers
Your shruti is the pitch of your Sa, and it should come from your voice: choose the scale where lower Pa still sounds clear and upper Sa is easy. As tendencies, many adult men sing around C to D♯ (1 to 2½ kattai) and many women around F to A♯ (4 to 6½ kattai), but voices vary a lot. The vocal range test measures your range first, so you can pick a Sa with numbers instead of guessing.
In Carnatic music the pitch is named in kattai: C is 1 kattai, C♯ 1½, D 2, D♯ 2½, E 3, F 4, F♯ 4½, G 5, G♯ 5½, A 6, A♯ 6½ and B 7 (there is no 3½, because E to F is a semitone). Harmonium players in Hindustani music count keys instead: white 1 (safed 1) is C, black 1 (kali 1) is C♯, white 2 is D, and so on up to white 7, B. This page shows both under the note, following the key numbering of the HBCSE (TIFR) harmonium worksheet and the usual kattai chart. A few teachers and boxes start the count on another note, so if a number does not match, trust the note name and the Hz.
Shruti box, tanpura or harmonium?
A shruti box is a small wooden box with free metal reeds and bellows: you open the stops for Sa, Pa or Ma and pump, and it holds those notes steadily. A tanpura is plucked: its four strings, usually tuned Pa–Sa–Sa–Sa, and its buzzing jawari bridge give a shimmering drone full of overtones. A harmonium has a keyboard, so besides drones it plays melodies and the swaras you are about to sing.
For a brighter, tanpura-style Sa, try the tanpura drone; to tune a real tanpura string by string, use the tanpura tuner. If you want to play sargam on keys while a Sa and Pa drone sounds underneath, open the online harmonium. For a drone on any note for other instruments, the general drone note page has the same engine with sine, triangle and organ tones.
Tips
- Tune your Sa with the drone alone first, then add Pa: a single Sa makes drifting easier to hear.
- Ragas that leave out Pa, such as Malkauns, are usually practised with Sa and Ma.
- With headphones, use the Shruti box or Sine tone at a low volume for long sessions.
- Change the scale one semitone at a time; if upper Sa feels hard, the scale is too high for today.
Frequently asked questions
Is this shruti box online free? Do I need an app?
It is free and runs in the browser on phones, tablets, laptops and PCs, with no download or sign-up. You can add the page to your home screen to open it like a shruti box app.
What do 1 kattai, 5 kattai and the other numbers mean?
Kattai is the Carnatic way of naming the pitch of Sa: 1 kattai is C, 1½ is C♯, 2 is D, 2½ is D♯, 3 is E, 4 is F, 4½ is F♯, 5 is G, 5½ is G♯, 6 is A, 6½ is A♯ and 7 is B.
What do white 1 and black 1 mean?
It is the harmonium key numbering used in Hindustani music: white 1 is C, black 1 is C♯, white 2 is D, black 2 is D♯, white 3 is E, white 4 is F, black 3 is F♯, white 5 is G, and so on to white 7, B.
Can I use this shruti box for Carnatic music?
Yes. Set your Sa in kattai, keep Sa and Pa, and practise sarali, janta and other varisais against it. The drone is the same for Carnatic and Hindustani singing.
When should I use Sa and Ma instead of Sa and Pa?
When the raga leaves out Pa, as Malkauns does, or when your teacher asks for a Ma drone. Tick Ma instead of Pa; the second reed moves from Pa (3:2) to Ma (4:3).
Is it the same as a real shruti box?
No. It is a synthesized reed tone with two slightly detuned reeds and no bellows, so its pitch never wavers. That steadiness is what a drone needs; the warmth of a wooden box needs the real instrument.
Does the page record my voice?
No. The shruti box does not use the microphone; it only plays sound, and your scale and settings are saved in this browser.