On Fri, 18 May 2007 08:28:06 -0400, "jack" wrote:

OK, and here's what the error on your network looks like when it is
simulated -- plugging the time constants into a "transfer function" -- you
should be able to do better than 0.1dB -- my Audio Research SP8 is acurate
to this level.

If you'll look carefully at Orig.png, attached to my original post,
you'll see that the resistor you've labelled R3 should be 47 ohms.

If you make this change, you should get an error curve like the one I've
attached to this post, showing that even with component values not equal to
the theoretical, the error is +- .01 dB.

If you use the theoretical values (good to only 12 digits), the error is
substantially better than +- 1 nano dB, limited only by the number of
digits used in the arithmetic. Your simulator will have to do its
computations with at least 12 digit arithmetic to see this result. The
RIAA curve you compare to must include a 4th time constant of .07492 uS
because that is what the theoretical values were calculated with.

The theoretical values are for these time constants:

T1 = 3180 uS
T2 = 318 uS
T3 = 75 uS
T4 = .07492 uS

R1 = 47.0000000000 ohms
R2 = 470454.868661 ohms
R3 = 68368.6219769 ohms
C1 = 4648.06079550 pF
C2 = 1595.29788607 pF

And, of course, these reference designators are the ones I used in my
original post, not the ones you chose.