What is Saptak?
Saptak stands for “gamut” or ” series of seven notes”. It comprises of the set of swaras, Sa, Re, Ga, Ma, Pa, Dha, Ni which makes up a musical scale in Indian classical music.  It is usually practiced against a drone.
What are the types of Saptak?
Hindustani classical music is made up of three saptaks namely, Mandra Saptak, Madhya Saptak, and Taar Saptak. The middle scale is called Madhya Saptak. This is the most used scale in singing. With reference to the Madhya saptak, the lower scale is known as Mandra or Kharaj Saptak and the higher scale is called as Taar Saptak.
Why to practice Saptak?
Practicing Saptak helps in increasing your vocal agility. Ascending and Descending the Saptak is a good vocal exercise for singers working on vocal agility. Hence, It is a good practice for anyone training to sing to practice Saptak on a daily basis. Singing the different Swaras in the saptak has a positive effect on the body, mind and the consciousness. The swaras also affect our feelings and emotions. Hence, practising swaras and saptaks have a very positive mental impact in our lives as well.
Concept of ‘Saptak’ and vocal registers
 – https://rajenjani.in/tag/mandra-saptak/
Other Important Hindustani Music Concepts