The Big 6

One of the most important foundation block of the theory of Carnatic music is the system of rAgas. Besides being a scientific system of classification, ragas are capable of generating one or emotions (or rasAs) - such as pathos (karuNa), devotion (bhakti), valour (vIrya), joy (hAsya), etc.

Although a great number of rAgas find place in concert renditions, six ragas stand out - in terms of classicism, popularity, grandeur, and even being yard-sticks to evaluate the vidwat of musicians. These ragas are (in order of their appearance in the mELakaRta scheme):

• tODi
• bhairavi
• kharaharapRiya
• kAmbhOji
• shankarAbharaNam
• kalyANi 

Alapanas and kRiti renditions in these rAgas usually happen to be the "main" item in Carnatic concerts - Purists such as MS Subbulakshmi, Semmangudi Srinivasa Iyer, DK Pattammal and KV Narayanaswamy would abide by this unwritten rule almost every time, although there is an increasing tendency these days to present RTPs (Ragam Tanam Pallavis) in sub-main rAgas (such as sAveri or latAngi), lighter rAgas (like behAg and kApi) or even rare rAgas and vivAdi rAgas.

Semmangudi

DK Pattammal

KV Narayanaswamy

MS Subbulaksmi

"The purists"

Four of these are mELa rAgas or parent rAgas, the other two are janya rAgas.  bhairavi inherits from the naTabhairavi mELa whereas kAmbhOji is a janya of the harikAmbhOji mELa. Interestingly, both are bhAshAnga rAgas; meaning they also have anya swarAs which are not found in their parent mELas. bhairavi takes the chaturashra dhaivata (D2) and it is used in the ascending sequences like P D2 N2 S. The descending passages remain true to the naTabhairavi mELa's structure, as in N2 D1 P. In the case of kAmbhOji, the anya swara is kAkali nishAda (N3) and is not as extensive in usage as D2 of bhairavi. N3 appears in what is called a vishesha pRayOga, which is S N3 P D2 S.

Another point to note is that kalyANi is the lone pRathi madhyama: all the other rAgas are shuddha madhyama. This is in concordance with the smaller number of pRathi madhyama rAgas that are in vogue.

Among the Trinity, contributions to kharaharapRiya have come in only from Saint Tyagaraja - it remains a mystery as to why the others didn't compose any kRitis in this rAga.

Most of the kRitis in these ragas are viLamba kAla (slow-tempo or medium-tempo) with long-drawn phrases, although there are a few racy numbers as well. This suggests the importance of gamakAs in these rAgas. 

Due to the sampooRNa (having all swaras) nature and also being samvAdi, these rAgas offer immense scope for improvisation - in particular, rAga AlApana can technically last for a long duration without the phrases getting redundant or repetitive. Stalwarts are known to have sung AlAps for hours; exploring new realms of creativity each time.