Yes, in my opinion, the high voltage (40-50V) is the key to the Boogie EQ. You'll need to put a lot of 9V batteries in series to get that kind of voltage in a pedal if you're going to try to implement the Boogie EQ circuit.
Also, because the design for the Boogie EQ is so old, it also uses real inductors and discrete transistors. The boogie EQ is weird and I don't think that anyone would build it that way today. It's not a bad design (no, it sounds quite good to me, in fact), it's just weird by today's standards.
A more modern design (like used common EQ pedals) would utilize op-amps and would probably not use inductors. Op-Amps and Inductor-less design is not necessarily inferior...in fact, they are usually much more consistent and repeatable from unit to unit (and in achieving the designer's desired center frequencies). The down-side of op-amps and inductor-less is that it might not sound, feel, or behave exactly the same as the boogie EQ. Notice the gigantic drop in mids in moving the 750Hz slider that last 1/4" from above the bottom to actually at the bottom? That's weird, and distinctly boogie. A modern design wouldn't necessarily do that.
Anyway, good luck with your EQ search. Simply buying an EQ pedal from the guitar store is probably the easiest approach. A rack EQ will have better quality, but then you've got to carry around a rack. Or you could trade your Boogie for one with the built-in EQ. Tough choices.
Chip
