Source Audio ZIO User Manual page 12

As seen above, the FOCUS control significantly shapes the low-end response of the pedal.
SCOOP Toggle Switch
The SCOOP Toggle Switch is a 2-way ON/OFF toggle switch. Flip to the ON (up) position to activate
the mid-scoop circuit. This circuit is an emulation of the Pultec equalizing trick, similar to the
"Studio" mode on the original guitar-focused ZIO: essentially a gentle low-mid cut to reduce "muddy"
frequencies, countered by a very subtle bass boost centered at 40Hz, and a rather dramatic shift in
the high frequencies, starting at 750Hz and peaking around 6kHz.
Shown below are frequency graphs of the SCOOP toggle switch in action, starting with flat (no
SCOOP, all other controls flat), then SCOOP enabled.
Flat:
SCOOP enabled:
SA272 ZIO Analog Bass Preamp + D.I. User Guide 12