Power for a 13.5V DC circuit

Hi all --

I have breadboarded out this circuit to make a snare drum sound: Image - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting

However, I would like to power this circuit with a 9V battery if it were possible. I have tried removing some components to lessen the circuit load, but they cause the sound to deteriorate.

This circuit needs at least 13V to sound good. Any ideas about how I could modify it so that it would only require 9V or less? Otherwise, I may just connect two 9Vs together and use a voltage divider for installing this circuit into a stomp box.