I am doing simulation on distortion on 3EF OPS. My base stop resistor from driver to power transistor is 3.3ohm. Base stop resistor from pre-driver to driver is 47ohm.
I get rid of all the base stop resistors and I lower the 3H by a little over 3dB at 30Vpeak output. That is significant!!! I tried reducing to 2.2ohm and 20ohm resp. It's only about 1dB reduction. When I reduce to 1ohm, that really helps also. But that's very low value.
I use 5 pairs of power transistors. My question is whether it's effective to use ferrite beats on the base lead instead to tame the oscillation. If so what kind?
Attached is the asc file, no base stop, 20 ohm on driver and 0.22ohm on power transistor, the last graph is 47ohm and 0.33 original.
In the asc file, the circuit on the right is the original circuit with 47ohm and 3.3ohm base stop. The left circuit is no base stop.
Thanks
I get rid of all the base stop resistors and I lower the 3H by a little over 3dB at 30Vpeak output. That is significant!!! I tried reducing to 2.2ohm and 20ohm resp. It's only about 1dB reduction. When I reduce to 1ohm, that really helps also. But that's very low value.
I use 5 pairs of power transistors. My question is whether it's effective to use ferrite beats on the base lead instead to tame the oscillation. If so what kind?
Attached is the asc file, no base stop, 20 ohm on driver and 0.22ohm on power transistor, the last graph is 47ohm and 0.33 original.
In the asc file, the circuit on the right is the original circuit with 47ohm and 3.3ohm base stop. The left circuit is no base stop.
Thanks
Last edited: