Look at the collector currents of Q6 and Q8. One not end and the other flows.
BE capacity is not enough to blow off steam, currents can be huge.
Reality is always much better. Thank measured and verified. In the measurement can be a problem, increase currents ...
Okay, I was confused because I didn't see these strange artifacts even at 1MHz. It turns out I've got enough OLG at those frequencies that they don't show up in the output devices but in the drivers. In fact, I have to drive it into .4 ohms just to see it. The slew rate of this amplifier is 124V/uS, at least in the simulator.
- keantoken
- keantoken
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Thank you.
I use very fast transistors for VAS and outputs, so this is less of a problem at high frequencies, than if you used, say 2N3055.
Of course, this is just simulation. Not to say it is not fairly accurate, but the circuit has a long ways to go yet if I decide to try building it.
Anyways, how do you get rid of these transverse currents? With this amp there is not much to gain at audio frequencies but... If I ever want to make my own radio station it'll be plug and play!
- keantoken
I use very fast transistors for VAS and outputs, so this is less of a problem at high frequencies, than if you used, say 2N3055.
Of course, this is just simulation. Not to say it is not fairly accurate, but the circuit has a long ways to go yet if I decide to try building it.
Anyways, how do you get rid of these transverse currents? With this amp there is not much to gain at audio frequencies but... If I ever want to make my own radio station it'll be plug and play!
- keantoken
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Just for the info, I based my circuit on this:
http://www.diyaudio.com/forums/solid-state/154670-my-folded-cascode-vas-linearity-investigation.html
I saw the opportunity to make a smoke machine with Q8 and Q9; the LTP can draw an (for the sake of discussion) indefinite amount of current out of Q8 and Q9, which then goes to the VAS transistors, which then supply an indefinite amount of current to the outputs, although by this time the VAS will be operating in class AB. Since Ic vs. Vbe is exponential, the LTP's don't have to go far to coax several hundred mA out of Q8 and Q9, which makes this amp fairly rugged if you give it good/enough OP's. Although considering, some current limiting should be in place so it doesn't destroy itself or a finger should it be shorted.
- keantoken
http://www.diyaudio.com/forums/solid-state/154670-my-folded-cascode-vas-linearity-investigation.html
I saw the opportunity to make a smoke machine with Q8 and Q9; the LTP can draw an (for the sake of discussion) indefinite amount of current out of Q8 and Q9, which then goes to the VAS transistors, which then supply an indefinite amount of current to the outputs, although by this time the VAS will be operating in class AB. Since Ic vs. Vbe is exponential, the LTP's don't have to go far to coax several hundred mA out of Q8 and Q9, which makes this amp fairly rugged if you give it good/enough OP's. Although considering, some current limiting should be in place so it doesn't destroy itself or a finger should it be shorted.
- keantoken
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To achieve the minimum Vdif, we set the best symmetry.
Working points are at the top characteristics.
An externally hosted image should be here but it was not working when we last tested it.
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