🚀 go-pugleaf

    I need the transfer function for the basic 3-band tone controls 
diagrammed below:

	       C1
in------------|  |-------	
	|		| Treble
	<		< Pt
     R1 >		><-----out
	<      C2	<
	|_____|  |______|
	|		|
	|		< Bass
	|		> Pb
	|      C3	<
	|_____|  |______|
			|
			< Midrange
			> Pm
			<
			|
   	              -----
  		       ---
		        -

Additionally, consider 2 cases:
	1. The circuit is buffered by op-amps.
	2. The circuit input is a high-impedance tube output and
           the circuit output is buffered.

Instead of a full transfer function, I imagine that good approximations
for the individual transfer function of each band would be more useful
since I just want to tweak things intelligently.

Thanks in advance,
jr