So what? The loads are connected to ground. That's where we measure them (those of us who actually build and test things) and how the voltages are detected by following stages (if one actually builds amplifiers). The symmetry forces their currents to cancel.
The "equal source impedance" model I presented gives accurate results. The fact that one can model it in other ways doesn't change that- the word "model" is the operant term here.
The "equal source impedance" model I presented gives accurate results. The fact that one can model it in other ways doesn't change that- the word "model" is the operant term here.
Try #908 as-is. It has equal Z and can drive non-linear loads into A2.
Because inductive couplings (at low frequency) prevent DC pumping.
The main coupling is capacitive, and not abusing transformer coupling
to even the split. Transformer has 2K2 incentive not to get involved
and let the caps do the job...
Change ratio of cathode feedback attenuation, so its not same as Mu.
Observe what non-equal Z's then do with non-linear but equal loads.
This test might be valid, because DC pumping is no longer complicating
interpretation of the result.
Even with local impedance not equal, global feedback path is probably
forcing splitter impedance very close to equal. We may have to open
the big loop too, to tell any difference.
Because inductive couplings (at low frequency) prevent DC pumping.
The main coupling is capacitive, and not abusing transformer coupling
to even the split. Transformer has 2K2 incentive not to get involved
and let the caps do the job...
Change ratio of cathode feedback attenuation, so its not same as Mu.
Observe what non-equal Z's then do with non-linear but equal loads.
This test might be valid, because DC pumping is no longer complicating
interpretation of the result.
Even with local impedance not equal, global feedback path is probably
forcing splitter impedance very close to equal. We may have to open
the big loop too, to tell any difference.
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"So what?" Well, here’s what: You now accept that you are measuring the P - K impedance, not two separate P and K to ground impedances.
The reason that your prediction is successful is that it is that P-K impedance, and not the P and K to ground impedances, that is crucial in determining balanced Cdyne operation.
It is wholly appropriate that you now place the name of your model, "equal source impedance" in quotes. Because you clearly haven't measured the impedances of the two sources which you claim to be equal. You’ve only measured the impedance of one.
It is crucial, when modeling, to know what is being modeled.
The reason that your prediction is successful is that it is that P-K impedance, and not the P and K to ground impedances, that is crucial in determining balanced Cdyne operation.
It is wholly appropriate that you now place the name of your model, "equal source impedance" in quotes. Because you clearly haven't measured the impedances of the two sources which you claim to be equal. You’ve only measured the impedance of one.
It is crucial, when modeling, to know what is being modeled.
KenPeter, I'd like to take a look at the 908 circuit and get a better feel for it. I think it'd be best to start with the simpler case, without global feedback, and then add it back in.
Do you have any thoughts about the difference between its operation and that of the earlier circuit with no caps bypassing the transformer? I guess the bandwidth of the newer one would be better.
Hope the beer was good. You don't mix that with soldering irons, do you?
Do you have any thoughts about the difference between its operation and that of the earlier circuit with no caps bypassing the transformer? I guess the bandwidth of the newer one would be better.
Hope the beer was good. You don't mix that with soldering irons, do you?
In this case, they are equivalent. The symmetry argument is a feature, not a bug.
Demonstrably false in general.
I have a three node network, P, K and ground. There is a 100 ohm resistor between P and K, a 10K resistor from P to (G)round and a 20K resistor from K to G.
The total impedances Zpg, Zkg and Zpk are unequal, and the sum of any two are unequal to the other.
It’s rather strange that you would be making predictions about impedances that we both now agree you were not measuring before, and in fact have yet to even propose, let alone prove, a correct method of testing.
I have a three node network, P, K and ground. There is a 100 ohm resistor between P and K, a 10K resistor from P to (G)round and a 20K resistor from K to G.
The total impedances Zpg, Zkg and Zpk are unequal, and the sum of any two are unequal to the other.
It’s rather strange that you would be making predictions about impedances that we both now agree you were not measuring before, and in fact have yet to even propose, let alone prove, a correct method of testing.
I interpreted "So what" in 941 to mean that you accept the point that you were only measuring Zpk. I stated that in 943. You had no response to that then. Why has it suddenly become an issue in 946? Are you suddenly claiming that you were measuring P and K to G impedances after all? Do we have to go back to that again?
At least don't go back on what you've already said. And let's not get off on a red hering.
I have a three node network, P, K and ground. There is a 100 ohm resistor between P and K, a 10K resistor from P to (G)round and a 20K resistor from K to G.
The total impedances Zpg, Zkg and Zpk are unequal, and the sum of any two are unequal to the other.
There is no promise of the symmetry you keep calling for. Simply because you have created a model that has symmetry and makes a prediction that is useful does not validate the model.
Your argument begs the question – assumes the conclusion. It’s similar to the following:
A model states that objects must be viewed through rose-tinted goggles to view the object’s color. The model’s statement that rose is the only color in existence is vindicated by implementing the model. Therefore, the model is correct.
At least don't go back on what you've already said. And let's not get off on a red hering.
I have a three node network, P, K and ground. There is a 100 ohm resistor between P and K, a 10K resistor from P to (G)round and a 20K resistor from K to G.
The total impedances Zpg, Zkg and Zpk are unequal, and the sum of any two are unequal to the other.
There is no promise of the symmetry you keep calling for. Simply because you have created a model that has symmetry and makes a prediction that is useful does not validate the model.
Your argument begs the question – assumes the conclusion. It’s similar to the following:
A model states that objects must be viewed through rose-tinted goggles to view the object’s color. The model’s statement that rose is the only color in existence is vindicated by implementing the model. Therefore, the model is correct.
Your constraints constrain your model – not the circuit. To assume otherwise is voodoo-like: make a model of something, do something to it, conclude the thing that was modeled must be affected. (Put on your rose-tinted goggles.)
You are simply begging the question: assume a model that requires balance. When the model does something useful, assume it correctly defines the circuit.
I already demonstrated that your model measured Zpk, not Zpg, not Zpk. You did not even attempt to refute that: your response was, "So what."
You have no basis on which to assert anything about something you haven't measured.
You are simply begging the question: assume a model that requires balance. When the model does something useful, assume it correctly defines the circuit.
I already demonstrated that your model measured Zpk, not Zpg, not Zpk. You did not even attempt to refute that: your response was, "So what."
You have no basis on which to assert anything about something you haven't measured.
No, it requires equal loads; balance is the result, not the constraint. You're putting words in my mouth again. Please refrain from that.
There is no imperative to assume a model that is capable only of handling a balanced case. That was your choice. The proper approach is to model the general case and then investigate specific ones, not jump to the conclusion you want and declare the model has proven itself. Rose tinted goggles again.
I'm describing what you're doing, not quoting you. There's a difference.
I've proven your model measures Zpk, not Zpg nor Zkg. You have provided no basis on which to make assertions about the latter two.
Willful ignorance of a proof, especially in the face of no attempt at its refutation, is no defense against its conclusions. For you, this proof is simply an inconvenient truth.
I'm describing what you're doing, not quoting you. There's a difference.
I've proven your model measures Zpk, not Zpg nor Zkg. You have provided no basis on which to make assertions about the latter two.
Willful ignorance of a proof, especially in the face of no attempt at its refutation, is no defense against its conclusions. For you, this proof is simply an inconvenient truth.
Other than experimental verification as the circuit is actually used. When you stoop to doing an actual experiment, I'll re-engage. Until then, this is useless.
There you go, threatening to run away from an inconvenient fact.
There is a thing called “design of experiment (DOE).” Unless you know what you’re measuring, it’s absurd to view bench testing as your salvation. There is no way to bench test a “design of experiment.” You must actually think it through. Unless you do, you’re just flailing away with a soldering iron and test clips.
I’ve proven why your design of experiment to measure Zkg and Zpg was flawed, and that you were measuring Zpk instead.
When you actually design an experiment which measures Zkg and Zpg, it might be worth the trouble of bench testing it. But I’d sure want to know why I couldn’t analyze it before I went through the trouble.
There is a thing called “design of experiment (DOE).” Unless you know what you’re measuring, it’s absurd to view bench testing as your salvation. There is no way to bench test a “design of experiment.” You must actually think it through. Unless you do, you’re just flailing away with a soldering iron and test clips.
I’ve proven why your design of experiment to measure Zkg and Zpg was flawed, and that you were measuring Zpk instead.
When you actually design an experiment which measures Zkg and Zpg, it might be worth the trouble of bench testing it. But I’d sure want to know why I couldn’t analyze it before I went through the trouble.
It's also pretty ironic that you demand that I experimentally verify the Figure 2 double-Thevenin test circuit that you presented in your article with an algebraic argument!
I'll provide experimental evidence that your test circuit puts no current into ground when AC-shorting ground to the P and K if you'll agree that that means that it's not measuring the plate and cathode impedances to ground.
Deal?
Or is this "experimental verification" stuff just another red herring?
I'll provide experimental evidence that your test circuit puts no current into ground when AC-shorting ground to the P and K if you'll agree that that means that it's not measuring the plate and cathode impedances to ground.
Deal?
Or is this "experimental verification" stuff just another red herring?
What you do in your spare time is your own business.
This whole discussion reminds me of Einstein trying to demonstrate that the Heisenberg uncertainty principle was false by constructing one thought experiment after another, all in vain. Why isn't there any discussion of the oscillograms from the original article that show the circuit to be intrinsically balanced?
John
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Difference that the first sim transformer coupled. And that transformer
phase splitting (non-intentional) would have invalidated the Cathodyne
experiment. There was also 2K2 damping in the signal path to prevent
the resonant LC tank (also non-intentional) from ringing.
The second moves 2K2 damping out of the signal path, and helps the
transformer look more like resistors to GND for audio frequencies, but
a short circuit to GND for DC. Cap coupling is dominant, and perhaps
close enough to a traditional setup to test some theories.
But there are yet a few minor problems holding back the experiment.
Both have the closed global negative feedback loop that needs to go.
And need to figure how we can dial cathode feedback from unity to 1/Mu
without ruining DC bias for cathode, or presenting uneven resistance for
the split.
What the beer lacked in quality was more than made up in quantity.
jlsem, I like your humor!
The Cdyne with identical P & K loads has equal and opposite P & K voltages (is that what you mean by "intrinsically balanced"?) It has to. Since the current going into the plate must come out the cathode and the loads are equal, Ohm’s Law demands this. There is no need to invoke Cdyne electrode impedances to obtain this outcome.
Tony, I'm pretty much a theoretical kind of guy. I’ve written a number of articles for Audio Amateur/xpress and EDN over the years. That, and maybe (re-)discovery and popularization of the Mu Follower have been my contributions. I find the analyses and derivations of circuit performance to be fascinating. That's probably why it's so important to me to get the basics right. If you’re looking for me to impress you with my designs, I’m afraid that’s not going to happen.
The Cdyne with identical P & K loads has equal and opposite P & K voltages (is that what you mean by "intrinsically balanced"?) It has to. Since the current going into the plate must come out the cathode and the loads are equal, Ohm’s Law demands this. There is no need to invoke Cdyne electrode impedances to obtain this outcome.
Tony, I'm pretty much a theoretical kind of guy. I’ve written a number of articles for Audio Amateur/xpress and EDN over the years. That, and maybe (re-)discovery and popularization of the Mu Follower have been my contributions. I find the analyses and derivations of circuit performance to be fascinating. That's probably why it's so important to me to get the basics right. If you’re looking for me to impress you with my designs, I’m afraid that’s not going to happen.
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