The B9 from Electro Harmonix is a great organ emulator for guitar and we take it one step farther giving you fine-tune control over the B9's on-board "Mod" knob by use of an external expression pedal or an extra on-board expression knob. The B9's Mod knob controls the speed of chorus/vibrato across all the various B9 modes.…this is what you would consider the rotary speaker effect and vibe'y type sounds of organs. By controlling the B9's Mod knob through expression, you can fine-tune your organ modulation on-the-fly and hands-free, just like you would a real organ.
After the Mod is complete, the red "Mod" knob on the B9 pedal will also allow you to set the limit on the maximum heel-down slow speed. [Please note: With the red knob all the way to the left, the expression will not operate.] As you rotate the red Mod knob to the right, you limit the slowest setting of available Mod knob.
Here are the Mod options:
Add Expression Jack:
This option allows you to plug in an expression pedal such as the M-Audio EX-P and control the B9's Modulation knob on-the-fly by use of the expression pedal. Using an expression pedal changes the speed of the B9's chorus/vibrato.