Jan Didden also managed to get an amplifier that is partly based on error feedforward to work, but he doesn't do the addition straight at the output. See
https://www.linearaudio.net/sites/linearaudio.net/files/UK-1 2008040241_0.pdf
or search for paX and Jan Didden.
Of course there is also QUAD current dumping. It does add the correction signal at the output, but the addition is frequency-dependent (voltage divider consisting of a resistor and an inductor). It's famous, so you can find information about it all over the place.
https://www.linearaudio.net/sites/linearaudio.net/files/UK-1 2008040241_0.pdf
or search for paX and Jan Didden.
Of course there is also QUAD current dumping. It does add the correction signal at the output, but the addition is frequency-dependent (voltage divider consisting of a resistor and an inductor). It's famous, so you can find information about it all over the place.
An opamp output cannot be coupled to a high power output with or without a capacitor because it is a low voltage and current device. The source and load impedance's of both signals need to be matched in order to influence the high-power output signal.
Your best high power option is probably a pair of equal amplifiers in bridge configuration across your load, one with your main signal the other with the error signal having the appropriate phase.
Your best solution is likely to be to add the error signal at low opamp level to the amplifier's input.
Your best high power option is probably a pair of equal amplifiers in bridge configuration across your load, one with your main signal the other with the error signal having the appropriate phase.
Your best solution is likely to be to add the error signal at low opamp level to the amplifier's input.
At first sight, it looks like a trivial variant of current dumping that they shouldn't have got a patent on.
"An opamp output cannot be coupled to a high power output with or without a capacitor because it is a low voltage and current device. The source and load impedance's of both signals need to be matched in order to influence the high-power output signal."
How do i do that?
"Your best high power option is probably a pair of equal amplifiers in bridge configuration across your load, one with your main signal the other with the error signal having the appropriate phase. Your best solution is likely to be to add the error signal at low opamp level to the amplifier's input."
It's not my best option. The best option is always to solve the problem, rather than get around it with excuses.
How do i do that?
"Your best high power option is probably a pair of equal amplifiers in bridge configuration across your load, one with your main signal the other with the error signal having the appropriate phase. Your best solution is likely to be to add the error signal at low opamp level to the amplifier's input."
It's not my best option. The best option is always to solve the problem, rather than get around it with excuses.
How about the first post on this marathon thread? (The consensus seems to have been that it’s not worth the effort, but enjoy experimenting!)
I realize that this solves a special case (crossover distortion), but it might give you some ideas.
I realize that this solves a special case (crossover distortion), but it might give you some ideas.
Current Dumping topology can achieve Class-A performance with zero biased output stage. It sounds like a fairy tale. Yet, it is true.
The famous Quad 405 amplifier is one of the examples. Please see the attached document if you want to learn more about Quad 405.
How it works, "Current Dumping for Dummies". https://connerlabs.org/current-dumping-for-dummies/
Conceptual Diagram.
What is crazier is that you can actually build it with an opamp. Modern opamps perform much better than than than the Class-A stage of Quad 405 back in 70s.
As the opamp is precompensated...
The famous Quad 405 amplifier is one of the examples. Please see the attached document if you want to learn more about Quad 405.
How it works, "Current Dumping for Dummies". https://connerlabs.org/current-dumping-for-dummies/
Conceptual Diagram.
What is crazier is that you can actually build it with an opamp. Modern opamps perform much better than than than the Class-A stage of Quad 405 back in 70s.
As the opamp is precompensated...
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Was there a consensus? I unwatched the thread somewhere around post 120 because it had turned into a rather erratic monologue. In any case, Acoustical/QUAD has sold current dumping amplifiers for decades and they work.
To be honest, I did the same. It got a bit annoying after a while. But if I recall correctly, based on the simulations they ran, I didn’t see any huge improvements over good old negative feedback.
Be that as it may, it does offer a way of adding the output of an opamp to the output of a power amplifier, which might help the OP.