• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Gyrator PSU's in tube amps

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hey guys,

I am going to give my SE amp a makeover in the coming weeks. New OPTs, new PT, maybe even going PSE. A guitar playing friend has recommended the use of a gyrator in the power supply. It sounds like a great idea on paper, however I've noticed that very few hi-fi designs use them. I would use it to eliminate electrolytic caps from the amplifier entirely. Why aren't there very many hi-fi amps that use this fairly simple design?

Regards
-Moose
 
A gyrator would present a dynamic impedance. In a guitar amp this would be desired as it creates the "voltage sag" that makes the guitar amp sound the way it does.

For hi-fi, a gyrator would be detrimental to the sound. Here we want to maintain a smooth, ripple free, low output impedance power supply that can handle transients easily. Try a voltage regulator or even a real CLC (capacitor-choke-capacitor) topology for the power supply. Google PSUD 2 to get the power supply designer.
 
A gyrator uses a capacitor to stand in for an inductor.
If you are trying to get rid of electrolytics, perhaps you meant a cap multiplier?
They are very similar circuits, yet react in opposite phase.

Both types have one issue in common. They do not store energy that can later
fill gaps in the ripple.
 
Last edited:
No, it's not a great idea, to use gyrator in PS. Just a R-C with high time constant feeding one source follower is much better. A parametric shunt regulator shunted by relatively big capacitance with source follower is even better: it brings up output voltage slowly and softly, and stays on the level stabilized by the shunt regulator.

Voltage sag can be created by a single additional R-C filter.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.