Gyrator Filter

[BRSHiFi]

http://www.triodeel.com/images/b9b.gif

The filters for this EQ look like a type of gyrator. Does anyone know the equations on how to calculate the resistor and capacitor values based off of Fc and Q?

The only reliable gyrator source I was able to find used opamps which are easy enough to work with, but nothing for tubes.

 

[Wavebourn]

So what is the difference?

 

[BRSHiFi]

The inverting and non inverting inputs are both used.

http://upload.wikimedia.org/wikipedia/commons/1/16/Op-Amp_Gyrator.svg

 

[tinitus]

thought I had seen another thread

http://www.diyaudio.com/forums/tubes-valves/210700-tone-controls.html

 

[Simon B]

Both inputs are shown as being used, and the diagram is a bit ic specific. The op-amp is wired as a unity gain voltage follower, with hi-z in, lo-z out.

Perhaps this might help:



The voltage follower can be implemented with valves, transistors or ic op-amps. This also applies to operational amplifiers.

 

[BRSHiFi]

Guitar Pedals: Gyrator Filter Calculator

I found a calculator here for determining the values of the center frequency and Q factor. Anyone know what the equations are?

I know that:

- The amplifier, R, and C substitute for an inductor. Each inductor has a Q factor. This can obviously be influenced by R and C for a synthetic inductor.

- RL is the series resistor for the inductor substitute.

- center frequency = BQ

- L = Rl * R * C