I don't think so because you can hear the oscillation through the speaker.
I think that is time for oscilloscope....
Ok. Here is the scope at the output, no load, no input signal.
Most of the time is 21.7Mhz.
Most of the time is 21.7Mhz.
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No, but changed with 22pf COG, same things.
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OK I think I know what's provoking this. Connect 100pF(not critical 220pF is ok too) NP0 between base and ground of Q5 and Q6. This is cascode and it can oscillate.
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Please Damir see post#130
Two smd 220pf cog one at the base of Q5 and one at the base of Q6.
Two smd 220pf cog one at the base of Q5 and one at the base of Q6.
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Yes I've seen it.
Could you add two more caps 220pF between other side of resistors R11, R12 and ground.
Yes but not now, i need a break 😉
Now i will start to thinking about those 5401,,5551.
They are from UTC.
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Ok. I wll try other 5401,5551 and your new suggestion tomorrow. 🙂
Is it tested by someone else?
Did you built this?
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You can try here BC546B and BC556B, be aware that pins are differently positioned.
I have tried both, same problem
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OITPC combine with ODNF? Interesting.
In all topology that use OITPC, I found at low level the harmonic level is almost monotonic, but at high level depend on topology. I think, OITPC only reduce high order distortion at low level.
I think in amplifier, output stage is highest distortion source. So, ODNF is one solution to reduce output stage distortion. But I do not like use op-amp for ODNF. I think, we can make discrete op-amp for ODNF easily, because it do not need DC precision and very low noise.
I hope we can make class AB amplifier with harmonic profile like class A. But we need new thread for this.