Zobel

[CSandrelli]

HI,
I built myself an amp with irfp240/9240 which has soft clipping at any frequency. I noticed that BEFORE the Zobel L//R network (0.7uH//10ohm) on a 10ohm//470nF load oscillates little, but AFTER the network oscillates a lot, as shown in the photo...in any case the probes are connected to the terminals of the amp and not after the meters of cable, is this behavior normal?
Thank you

 

[kapitiaudio]

I think some ringing is normal with the output inductor. If you want to reduce it, you can reduce the value of the damping resistor from 10R to something like 2R2.

 

[rayma]

Yes, that is passive ringing, not oscillating.

 

[Hennady Kovalsky]

в

I noticed that BEFORE the Zobel L//R network (0.7uH//10ohm) on a 10ohm//470nF load oscillates little, but AFTER the network oscillates a lot, as shown in the photo...in any case the probes are connected to the terminals of the amp and not after the meters of cable, is this behavior normal?

This is how it looks in the model (see attachments) I took as an example a common amplifier based on bipolar transistors

 

[Hennady Kovalsky]

here is a version of a composite amplifier with an L/R circuit, here 0.7uH / 2 Ohm.