Dave, please tell me which of my two circuits in 735 isn't balanced and why. I'm serious; this is not a rhetorical question. Please reply.
The one with no loads, a 10.1Kohm plate resistor and a 10K ohm cathode resistor?
Or the one with total loads seen by both the P and K as 10K?
I'll comment on your sims in the subsequent post.
The one with no loads, a 10.1Kohm plate resistor and a 10K ohm cathode resistor?
Or the one with total loads seen by both the P and K as 10K?
I'll comment on your sims in the subsequent post.
Chris,
How is starting with unbalanced loads and balancing them any different from starting with balanced loads and unbalancing one?
you need to change the load at both nodes at the same time.
here is what I get when I use your values.
Notice that the output impedance of the plate is now 1.5K || 10.1K and that of the cathode is 1.5K||10K
dave
How is starting with unbalanced loads and balancing them any different from starting with balanced loads and unbalancing one?
you need to change the load at both nodes at the same time.
here is what I get when I use your values.
Notice that the output impedance of the plate is now 1.5K || 10.1K and that of the cathode is 1.5K||10K
dave
Dave, regarding your sims in 740:
The simplest way for me to express the problem I have with what you advocate in 740 is as follows. Please tell me if you disagree with anything in the steps below, and why. Please don’t ignore the things I write the way some do. I am more than willing to reply to everything you propose. I ask a similar commitment of those whom I agree to discuss things with.
1. Suppose I created a circuit similar to a Cdyne, but I used it as a single ended amplifier with a P resistor of 10K and a K resistor of 5K.
2. There is nothing to keep balanced in this circuit.
3. To determine the resistance at any point in this circuit, I divide V_open_circuit by I_short_circuit.
4. To determine Zplate, I note Vp_open_circuit. I short P to ground through a 1e-99 ohm resistor and measure the current through it. I divide the voltage by the current to get Zp.
5. Now I slowly increase the K resistor to 10K. Eventually, the K and P resistors are both 10K. At this point, without touching the circuit, I change my mind and decide I want use it as a balanced Cathodyne.
6. Please explain at what point and why in the process of step 5 I suddenly have to change my impedance test method to add a short to ground at K. (It would surely give me the wrong answer to do so in step 1!)
The simplest way for me to express the problem I have with what you advocate in 740 is as follows. Please tell me if you disagree with anything in the steps below, and why. Please don’t ignore the things I write the way some do. I am more than willing to reply to everything you propose. I ask a similar commitment of those whom I agree to discuss things with.
1. Suppose I created a circuit similar to a Cdyne, but I used it as a single ended amplifier with a P resistor of 10K and a K resistor of 5K.
2. There is nothing to keep balanced in this circuit.
3. To determine the resistance at any point in this circuit, I divide V_open_circuit by I_short_circuit.
4. To determine Zplate, I note Vp_open_circuit. I short P to ground through a 1e-99 ohm resistor and measure the current through it. I divide the voltage by the current to get Zp.
5. Now I slowly increase the K resistor to 10K. Eventually, the K and P resistors are both 10K. At this point, without touching the circuit, I change my mind and decide I want use it as a balanced Cathodyne.
6. Please explain at what point and why in the process of step 5 I suddenly have to change my impedance test method to add a short to ground at K. (It would surely give me the wrong answer to do so in step 1!)
OK boys and girls.
The job today is to design an LCR phono stage and we have a box full of ideal 6K LCR RIAA modules to use.
The boss says we need a single ended output and the ability to invert phase and demands the input signal must feed the grid of a 6DJ8 with matched 22K resistors in the plate and cathode. It is also required that the 6K LCR be driven from exactly a 6K source.
What value resistor do you place in series with the input of the LCR fed by the plate?
What value resistor do you place in series wiht the input of the LCR fed by the cathode?
dave
The job today is to design an LCR phono stage and we have a box full of ideal 6K LCR RIAA modules to use.
The boss says we need a single ended output and the ability to invert phase and demands the input signal must feed the grid of a 6DJ8 with matched 22K resistors in the plate and cathode. It is also required that the 6K LCR be driven from exactly a 6K source.
What value resistor do you place in series with the input of the LCR fed by the plate?
What value resistor do you place in series wiht the input of the LCR fed by the cathode?
dave
I would think things change when you decide you are interested in the output of both the plate and the cathode at the same time.
As for my problem.... Please help me... The boss is breathing down my neck and I can't screw up because Christmas is around the corner, and I ain't gonna have no money to buy my son the G.I. Joe with the kung-fu grip!
dave
As for my problem.... Please help me... The boss is breathing down my neck and I can't screw up because Christmas is around the corner, and I ain't gonna have no money to buy my son the G.I. Joe with the kung-fu grip!
dave
Yes . . . probably
ut the RIAA filter before the PI so your question will really be OT Yves.
I fail to see how my situation is off topic. It is simply showing an application using a cathodyne where the source impedance needs to be increased to a specific value in order to make a filter behave properly.
It is an actual real world application that can be measured and verified.
I only get one chance at picking those resistors and K-mart is having a sale on toys.
dave
It is an actual real world application that can be measured and verified.
I only get one chance at picking those resistors and K-mart is having a sale on toys.
dave
When you manipulate only the plate you get the plate output impedance.
When you manipulate only the cathode, get the cathode output impedance.
When you manipulate both you get the cathodyne output impedance.
Quid Pro Quo.
A friend called me and there are only 4 GI-joes with kung-fu grip left on the shelves.
what values of resistors do I use?
I think it should be 6000- the source impedance from the plate and 6000- the source impedance from the cathode but what numbers do I use for those impedances?
dave
dave
When you manipulate only the cathode, get the cathode output impedance.
When you manipulate both you get the cathodyne output impedance.
Quid Pro Quo.
A friend called me and there are only 4 GI-joes with kung-fu grip left on the shelves.
what values of resistors do I use?
I think it should be 6000- the source impedance from the plate and 6000- the source impedance from the cathode but what numbers do I use for those impedances?
dave
dave
Dave, I'm sorry, but I don't see how your response answers my question. I don't have the "that" yet.
I want to know at what step in the process I described the method of impedance measurement has to change and why. Please address the steps and the final question and give me an answer or find a flaw somewhere.
Circuit parameters and measurement techniques don't change simply because people's intentions do.
Can you please draw a block diagram for your problem to clarify it so that we can start to think about it. (You can leave out the G.I. Joe pictures. )
I want to know at what step in the process I described the method of impedance measurement has to change and why. Please address the steps and the final question and give me an answer or find a flaw somewhere.
Circuit parameters and measurement techniques don't change simply because people's intentions do.
Can you please draw a block diagram for your problem to clarify it so that we can start to think about it. (You can leave out the G.I. Joe pictures. )
OK.
here is the block diagram. you can pick any tube you want and name your plate and cathode impedances. Use a 12AX7 and insert a negative value for R if you feel you need to.
I also want to mention that the ideal 6K LCR is a constant impedance "T" network that provides a 6K load to the source independent of what happens behind it.
(edit) oops... forgot the coupling caps to the LCR. Please mentally insert them and consider them infinite and ideal.
Sorry for the following but ever since I..... ummm.... I mean my boy saw Billy Valentine talk of the kung fu grip he just needed to have it.
dave
here is the block diagram. you can pick any tube you want and name your plate and cathode impedances. Use a 12AX7 and insert a negative value for R if you feel you need to.
I also want to mention that the ideal 6K LCR is a constant impedance "T" network that provides a 6K load to the source independent of what happens behind it.
(edit) oops... forgot the coupling caps to the LCR. Please mentally insert them and consider them infinite and ideal.
Sorry for the following but ever since I..... ummm.... I mean my boy saw Billy Valentine talk of the kung fu grip he just needed to have it.
dave
Last edited:
OK, Dave, thanks for the block diagram, I'll think on it. The problem seems to simplify to thinking of the LCR as a 6K load looking toward (but not connected to) the Cdyne.
Also, the LCRs inputs must see 6K.
We get to choose R1=R2, ?1 and ?2.
Please provide answers to posts 745 and 746 and I'll give you my reply.
Also, the LCRs inputs must see 6K.
We get to choose R1=R2, ?1 and ?2.
Please provide answers to posts 745 and 746 and I'll give you my reply.
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