Manley MASSIVE PASSIVE STEREO TUBE EQ - MSMP 1998 - 2/2004 - Manual (Page 13)

Normal Shelf Wide Bandwidth
(slope =about 4 to 5 dB/oct)
Special Shelf Medium Bandwidth
(slope = about 8 to 10 dB/oct)
"Pultec Shelf" Narrow Bandwidth
Bell Cut Narrow Bandwidth
(just for reference)
22 Hz Shelf Wide Bandwidth
22 Hz Shelf Narrow Bandwidth
33 Hz Shelf Wide Bandwidth
33 Hz Shelf Medium Bandwidth
22Hz and 33Hz are different shelves when the Bandwidth is Narrow
The top graph is for the other 20 Low shelves
LOW SHELF CURVES
Just like most EQs, a 100Hz low shelf
doesn't reach "max" until about 10 Hz.
13