The tambura, tanpura, tamburi (Bengali: তানপুরা) is a long-necked plucked lute (a stringed instrument) found in different forms in Indian music culture. Hindustani musicians speak of 'tanpura' whereas Carnatic musicians say 'tambura'; 'tamburi' is a smaller instrument used for accompanying instrumental soloists. For practical use, all these types are called 'tanpura' in the text.
The body shape of the tanpura somewhat resembles that of the sitar, but it has no frets – as the strings are always plucked at their full lengths. One or more tanpuras may be used to accompany vocalists or instrumentalists. It has four or five (rarely six) wire strings, which are plucked one after another in a regular pattern to create a harmonic resonance on the basic note or keynote (bourdon or drone function). Tanpuras form the root of the ensemble and indeed of the music itself, as the tanpura creates an acoustic dynamic reference chord from which the ragas derive their distinctive character, color and flavor. Concerning its history, a quote from A. D. Ranade: 'The first unambiguous reference to the tanpura is in Sangit Parijat (1620). It is neither mentioned by the earlier texts nor does it find a place in sculptures'. An electronic tanpura, a small box that imitates the sound of a tanpura, is often used in contemporary Indian classical music performances instead of, or in addition to a tanpura.
Tanpuras come in different sizes and pitches: larger "males", smaller "females" for vocalists, and a yet smaller version is used for accompanying sitar or sarod, called tamburi. Male vocalists pitch their tonic note (Sa), often at C♯; female singers usually a fifth higher, though these tonic notes may vary according to the preference of the singer, as there is no absolute and fixed pitch-reference in the Indian classical music systems. The male instrument has an open string length of approximately one metre; the female is three-fourths of the male. The standard tuning is 5-8-8-1 (sol do' do' do) or, in Indian sargam, PA-sa-sa-SA. For ragas that omit the fifth tone, pa, the first string is tuned down to the natural fourth: 4-8-8-1 or Ma-sa-sa-Sa. Some ragas require a less common tuning with shuddh NI (one semitone below octave sa), NI-sa-sa-SA. With a five-string instrument, the seventh or NI (natural minor or major 7th) can be added: PA-NI-sa-sa-SA (5-7-8-8-1)or MA-NI-sa-sa-SA (4-7-8-8-1).
The name tanapura is probably derived from tana, referring to a musical phrase, and pura, which means "full" or "complete". Both in its musical function and how it works, the tanpura is unique in many ways. It does not partake in the melodic part of the music, but it supports and sustains the melody by providing a colourful and dynamic harmonic resonance field based on one precise tone, the basic note or key note. Also, it is not played in rhythm with the music, as the precise timing of plucking a cycle of four strings in a continuous loop is a determinant factor in the resultant sound.
The special overtone-rich sound and the audible movement in the inner resonances of tone is achieved by applying the principle of jivari or 'jawari' which creates a sustained "buzzing" sound in which particular harmonics will resonate with focused clarity. Jiva refers to "soul", that which gives life, implying that the tanpura embodies an "animated" tone quality. Another linguistic reference is 'sawari' which means 'saddle'. The principle of jivari can be compared to the prismatic refraction of white light into the colours of the rainbow, as its acoustic twin principle at work, amplifying the inner resonances of a tone to audible harmonics.
To achieve this effect, the strings pass over a wide, arched bridge, the front of which slopes gently away from the surface of the strings. When a string is plucked, it has an intermittent periodical grazing contact with the bridge; this intermittent grazing of the string on the curved bridge will move around in the sonation process, as the points of contact will gradually shift, being a compound function of amplitude, the curvature of the bridge, pitch and string tension. When the string is plucked, it has a large amplitude, moving up and down and contacting the bridge on the down-phase. As the energy of the string's movement gradually diminishes, the contact point of the string with the bridge slowly creeps up the slope of the bridge like a wave out of the sea spending itself on the beach. Depending on scale and pitch, this can take between three and ten seconds. This dynamic process can be fine-tuned using a cotton thread between string and bridge: by shifting the thread, the grazing contact sequence is shifted to a different position on the bridge, changing the harmonic content. Every single string produces its own cascading range of harmonics and, at the same time, builds up a particular resonance. According to this principle, tanpuras are attentively tuned to achieve a particular tonal shade relative to the tonal characteristics of the raga. These more delicate aspects of tuning are directly related to what Indian musicians call raga svaroop, which is about how characteristic intonations are important defining aspects of a particular raga. The tanpura's particular setup, with the cotton thread as a variable focus-point, made it possible to explore a multitude of harmonic relations produced by the subtle harmonic interplay in time of its four strings.
Tanpuras are designed in three different styles:
- Miraj style: the favourite form of tanpura for Hindustani performers. It is usually between three to five feet in length, with a carved, rounded resonator plate (tabli) and a long, hollow straight neck, in section resembling a rounded capital D. The round lower chamber to which the tabli, the connecting heel-piece and the neck (dandh) are fixed is cut from a selected and dried gourd (tumba). Wood used is either tun or teak; bridges are usually cut from one piece of bone.
- Tanjore style: this is a south Indian style of tambura, used widely by Carnatic music performers. It has a somewhat different shape and style of decoration from that of the miraj, but is otherwise much the same size. Typically, no gourd is used, but the spherical part is gouged out of a solid block of wood. The neck is somewhat smaller in diameter. Jackwood is used throughout; bridges are usually cut from one piece of rosewood. Often, two rosettes are drilled out and ornamented with inlaywork.
- Tamburi: small-scale instruments, used for accompanying instrumental soloists. It is two to three feet long, with a flat bed-pan type wooden body with a slightly curved tabli. It may have from four to six strings. Tamburi are tuned to the higher octave and are the preferred instruments for accompanying solo performances by string-playing artists, as the lighter, more transparent sound does not drown out the lower register of a sitar, sarod, or sarangi. To simply state that the tanpura supplies the drone in the tonic key is accurate insofar that it is an understatement: the tanpura-accompaniment is the "alpha et omega" of melody, or rather, ragas. In the hands of masters the tanpura will reveal the precise tonal shade that is perfectly suited for the chosen raga that will be played or sung.
- "FUNDAMENTALS OF RAG". chandrakantha. Retrieved 3 June 2013.
- Shri Ashok D. Ranade:Hindustani Classical Music, Keywords and concepts, New Delhi: Promilla & Co 1990, source for Sangit Parijat is Ahobal Pandit, translated by Kalind-Hatvas, Sangeet Karyalaya 1971
- Wim van der Meer - Joep Bor: De roep van de Kokila, historische en hedendaagse aspekten van de Indiase muziek; Martinus Nijhoff / 's-Gravenhage 1982, ISBN 90 247 9079 4
- Hindustani Music, 13th to 20th centuries, editors: Joep Bor, Françoise Delvoye, Jane Harvey & Emmy te Nijenhuis; Codarts, Manohar 2010
- Nazir Ali Jairazbhoy:The Rags of North Indian Music: Their Structure and Evolution Popular Prakashan:Bombay 1995, ISBN 81-7154- 395-2 (First published by Faber and Faber, 1971)
- http://repository.ias.ac.in/69870/1/69870.pdf Sir C V Raman, FRS, M.A., D.Sc. (Hon), Palit Professor of Physics at Kolkata University, Nobel Prize, 1930: On some Indian string instruments (1921)
- http://scholar.google.nl/scholar?hl=nl&q=P.K.+Pandya%3A+Beyond+Swayambhu+Gandhar&btnG=&lr= (article by P.K. Pandya: Beyond Swayambhu Gandhar: an analysis of perceived tanpura notes)
- Audio samples: http://glorian.bandcamp.com/album/tanpura-sounds-2 (recordings of tanpura at various pitches)
- see the article:  In this essay the essentials of the tanpura are discussed, its essential function as harmonic foundation in Indian Classical Music, how the characteristic sound is attained, information on the intricacies of tuning and in which, in short, its musical and artistic merits are elaborated. The versatility in tuning and the natural beauty of the sound of an expertly maintained and tuned instrument is argued to be its own best defense against the less demanding electronic tanpura, which ultimately is a one-size-fits-all matter that will not help music forward in the long term.