The Sphere 900 Graphic EQ offers nine frequencies occurring in natural octave steps, that can be boosted or cut simultaneously. The rotary switches offers a visual display of the shape of the audio signal being modified. 

The frequencies are 50,100,200,400,800,1600,3200,6400 and 12800Hz. The presence range of 6.4 kHz can be shifted to 8kHz or 5kHz, or (if both switches are in the on position) to 4kHz. Each frequency can be boosted to +12db or attenuated to-15db.