Impedances question

[Rafa]

In a tonestack; is the same the original circuit compared to a ciruit which is exactly the same but all the impedances are divided by a factor of 50 for eg?

[frank_p]

Are you talking about all the values that are in in tone-stack ? I think you don't see the problem correctly. If all values of the components are divided by a factor, only the shape of the effect on different frequencies (all values changes) would be conserved.  You have to work in the frequecy domain or complex plane.

[R.G.]

If you change the impedance of all the parts by the same factor, the frequency behavior of the tone stack remains exactly the same.

What is NOT the same is the effect on the source driving the input to the tone stack, and the input to the signal after the tone stack. If you lower the impedance of all parts of the tone stack, then the source driving into the tone stack must work that factor harder. For instance, if you lower everything by 10:1, then it takes 10 times as much current to drive the tone stack to the same voltages; so the driver must be able to provide that current. This is not always true with a tube driving a tone stack, so you may have to put a cathode follower onto it to drive the tone stack.

If you raise the impedance of the whole tone stack, then its output impedance is raised, and the tone stack cannot drive as low an impedance following stage.