Dual Amplifier Band Pass

I've modified the Sedra-Espinosa design to enable use of the DABP in parametric equalizers. The new constant Q control provides a range of 0.4 to ~2.7 as drawn. Modification for high-Q applications is simple, with a Johnson noise tradeoff at the input. For mastering engineers and light-touch mixers seeking a very low noise, low-Q design, this may be a better starting point than the State Variable Filter. It involves no inversion or summing and it can be set up for a Q range of 0.2 to 1.0 with just a triple 10k log pot.