Version 4
SHEET 1 1760 680
WIRE -16 48 -80 48
WIRE 112 48 64 48
WIRE 368 48 112 48
WIRE 368 64 368 48
WIRE 112 80 112 48
WIRE 256 144 208 144
WIRE 368 144 368 128
WIRE 368 144 336 144
WIRE -80 192 -80 48
WIRE 112 208 112 160
WIRE 368 208 368 144
WIRE 208 240 208 144
WIRE 208 240 144 240
WIRE 496 240 400 240
WIRE 560 240 496 240
WIRE 496 288 496 240
WIRE 208 336 208 240
WIRE 256 336 208 336
WIRE 368 336 368 272
WIRE 368 336 336 336
WIRE 368 352 368 336
WIRE -80 448 -80 272
WIRE 112 448 112 272
WIRE 112 448 -80 448
WIRE 368 448 368 416
WIRE 368 448 112 448
WIRE 496 448 496 368
WIRE 496 448 368 448
WIRE -80 480 -80 448
FLAG -80 480 0
FLAG 560 240 OUT
IOPIN 560 240 Out
SYMBOL res 96 64 R0
WINDOW 3 40 74 Left 2
WINDOW 0 45 37 Left 2
SYMATTR Value 100k
SYMATTR InstName R2
SYMBOL res 80 32 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 39k
SYMBOL cap 352 64 R0
WINDOW 0 43 6 Left 2
WINDOW 3 42 33 Left 2
SYMATTR InstName C1
SYMATTR Value 330pF
SYMBOL cap 352 352 R0
WINDOW 0 45 24 Left 2
WINDOW 3 42 51 Left 2
SYMATTR InstName C2
SYMATTR Value 2.7nF
SYMBOL voltage -80 176 R0
WINDOW 0 7 110 Left 2
WINDOW 123 7 136 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value2 AC 1
SYMATTR Value ""
SYMBOL res 352 128 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 2.2Meg
SYMBOL res 352 320 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R4
SYMATTR Value 220k
SYMBOL res 480 272 R0
SYMATTR InstName R5
SYMATTR Value 1Meg
SYMBOL Misc\\urc 128 288 R180
WINDOW 0 72 76 Right 2
WINDOW 3 41 49 Left 2
WINDOW 123 40 14 Left 2
SYMATTR InstName P1
SYMATTR Value {Rbass}
SYMATTR Value2 n={k}
SYMATTR Prefix X
SYMATTR SpiceModel aud r=
SYMBOL Misc\\urc 384 288 R180
WINDOW 0 72 76 Right 2
WINDOW 3 41 50 Left 2
WINDOW 123 40 20 Left 2
SYMATTR InstName P2
SYMATTR Value {Rtreb}
SYMATTR Value2 n={k}
SYMATTR Prefix X
SYMATTR SpiceModel aud r=
TEXT -16 536 Left 2 !.param Rbass=500k
TEXT -16 568 Left 2 !.param Rtreb=250k
TEXT -16 496 Left 2 !.ac oct 40 80 8000
TEXT -16 616 Left 2 !.step param k 0 1 0.1111
TEXT 320 496 Left 2 !.subckt aud 1 2 3 ; audio taper\n.params r=1e6, n=.5\n+ x=100**limit(.001,n,.999)/100\nRa 1 3 {x*r}\nRb 3 2 {(1-x)*r}\n.ends aud