Below you will find the location of each of the Jecht Spheres in Final Fantasy X.

Locations:
1st Jecht Sphere: Spherimorph Boss Fight, Macalania.
2nd Jecht Sphere: Besaid Village, to the right of the temple entrance.
3rd Jecht Sphere: SS Liki, on the bridge board at Besaid.
4th Jecht Sphere: Luca stadium, Basement A.
5th Jecht Sphere: Mi’ihen highroad, oldroad, south.
6th Jecht Sphere: Moonflow, South Wharf.
7th Jecht Sphere: Thunder Plains, South.
8th Jecht Sphere: Macalania Woods, South.
Auron’s Sphere: Mushroom Rock Road, Precipice.
Braska’s Sphere: Mountain Trail, Mt. Gagazet.