On the dark Esquire circuit reduce the value of the cap that's going to ground and you'll get volume back, try from .05 or whatever's in there to .01. More volume less capacitance so you could go down to 5 nanofarads. The resistor is the resonant peak and the cap in series with the resistor is the resonant frequency. Leave the resistor, try a .03uf. Want more highs try .02uf. The resistor will keep the emphasis on the lows.