There are so many things that you can achieve with passive EQ options (capacitor value, pot value, phase, tone, etc). But how are active EQ's created? Take the OBP-3... it's a box. You send wires to pots and you control the box. How do they create it? Is it computer-style wizardry or a complex setup of micro-capacitors and resistors and such? Is there any info in books or on the web that shows you how to create an active preamp from scratch? Obviously, Mike Pope, The guys from EMG, Mr. Aguilar, Roger Sadowsky, and Bill Bartolini (to name a few) learned somewhere how to do this.