## Using Laplace equations for inverse RIAA

LT spice, Curve Captor, PSUDII and whatever other sims you can think of.

andyn
Posts: 6
Joined: Mon Nov 26, 2007 2:22 pm

### Using Laplace equations for inverse RIAA

I had a look thru the Help text and did a Google. I understand the equation to use to construct an inverse RIAA which is

laplace=(1+1.003180*S)*(1+1.000075*S)/((1+1.000318*S)*(1+1.00000318*S))

if one wishes to include the 3.18uS time constant as well.

I have tried the voltage controlled current source but to no avail. I get a variety of error messages.

Does anyone have the answer?

It seems doing things with a laplace equation may be easier and also quicker than an inverse RIAA network - which vary in accuracy.

AndyN
jlevro
Posts: 1
Joined: Thu Aug 04, 2011 1:48 pm

### Re: Using Laplace equations for inverse RIAA

andyn wrote:I had a look thru the Help text and did a Google. I understand the equation to use to construct an inverse RIAA which is

laplace=(1+1.003180*S)*(1+1.000075*S)/((1+1.000318*S)*(1+1.00000318*S))

if one wishes to include the 3.18uS time constant as well.

I have tried the voltage controlled current source but to no avail. I get a variety of error messages.

Does anyone have the answer?

It seems doing things with a laplace equation may be easier and also quicker than an inverse RIAA network - which vary in accuracy.

AndyN
Sorry, I just stumbled across this, and I don't see that it's ever been answered.

Use a voltage-dependent voltage source (e or e2). Set the value to:

Laplace=(((s*T0+1)*(s*T2+1))/((s*T1+1)*(s*T3+1))). Then add Spice directives:

.param T0=3180us
.param T1=318us
.param T2=75us
.param T3=3.18us

Seems to work for me.

JL