I know that. I also know its a long thread. Folks keep coming at me from the wrong angle. I used that as a reason for evidence of something else....
The whisper game, is now the reading game...
I have been guilty of jumping into a thread thinking I was on track, meanwhile I was way off... so I get it..
Its all good, and TY for the links...
If I keep typing, someone will say I'm reinventing the wheel or the wheel was never really needed, or ...
Maybe try this: referring to tikiroo's excellent example in post #32, notice that the idling point he chose, 200 VDC and 40mA, is the same for both examples.
This is also true for both DC and AC loadlines. Both pass thru a common center point at idle. In fact, both are special cases, and there are an infinite number of real loadlines, different at every frequency, and they all pass through the same idle point.
The special case of DC, zero frequency, is the most vertical, and is a straight line. At all other frequencies, the loadline is rotated counterclockwise (more horizontal), but all pass through the idling point. At .0001 Hz the loadline is only very slightly different than for DC. At higher frequencies, reactive components start becoming significant.
When we get up into the operating range of the output transformer it (the transformer) becomes perfect enough to be ignored, and only its reflected load need be considered. We pretend that this is a resistor, although real speakers are definitely not, and draw a mythical loadline representing what the mythical resistor would do. We call *this* the AC loadline, although we all really know it's a fiction, a working concept. Note that this loadline, like all others, passes through our idling point.
At still higher frequencies, above the working range of the transformer, parasitic capacitances dominate the load, so the loadline starts to rotate clockwise. And at very, very high frequencies the loadline rotates back closer and closer to the DC loadline.
Off topic, but perhaps interesting later, real loadlines are always elliptical because parasitic reactive components are always present. If the load is elliptical enough, we need to insure that it all fits onto our graph. (Single-ended amplifiers cannot have negative current. Semicon amplifiers have SOA limitations. Etc.)
All good fortune,
Chris
This is also true for both DC and AC loadlines. Both pass thru a common center point at idle. In fact, both are special cases, and there are an infinite number of real loadlines, different at every frequency, and they all pass through the same idle point.
The special case of DC, zero frequency, is the most vertical, and is a straight line. At all other frequencies, the loadline is rotated counterclockwise (more horizontal), but all pass through the idling point. At .0001 Hz the loadline is only very slightly different than for DC. At higher frequencies, reactive components start becoming significant.
When we get up into the operating range of the output transformer it (the transformer) becomes perfect enough to be ignored, and only its reflected load need be considered. We pretend that this is a resistor, although real speakers are definitely not, and draw a mythical loadline representing what the mythical resistor would do. We call *this* the AC loadline, although we all really know it's a fiction, a working concept. Note that this loadline, like all others, passes through our idling point.
At still higher frequencies, above the working range of the transformer, parasitic capacitances dominate the load, so the loadline starts to rotate clockwise. And at very, very high frequencies the loadline rotates back closer and closer to the DC loadline.
Off topic, but perhaps interesting later, real loadlines are always elliptical because parasitic reactive components are always present. If the load is elliptical enough, we need to insure that it all fits onto our graph. (Single-ended amplifiers cannot have negative current. Semicon amplifiers have SOA limitations. Etc.)
All good fortune,
Chris
Chris,
I will try and grasp all said earlier. That said, I honestly only wanted to understand 1/2 of step 2, but as things go, folks felt it important to throw in the OPT and ac analysis to step 20. I hadn't gotten that far lol... My fault, but I suspect nothing engineered correctly in my amp. I suspect it might be close enough but not close enough for me. Its a hunch, and unfounded but I figured I would start with a known issue in this amp. I have measured the WR of the OPT and on 8 ohm tap have 18:1 and 4 ohm tap have 26:1..
I will try and grasp all said earlier. That said, I honestly only wanted to understand 1/2 of step 2, but as things go, folks felt it important to throw in the OPT and ac analysis to step 20. I hadn't gotten that far lol... My fault, but I suspect nothing engineered correctly in my amp. I suspect it might be close enough but not close enough for me. Its a hunch, and unfounded but I figured I would start with a known issue in this amp. I have measured the WR of the OPT and on 8 ohm tap have 18:1 and 4 ohm tap have 26:1..
Doh!
Chris, (and to all who tried in earnest to penetrate my extra thick cranium)
The following Universal loadline calculator for vacuum tubes - Vacuum Tube Amplifiers - DIY
tied EVERYTHING up lol..
Now, I get it. And, re-reading what was written, well.. I'm pretty much freaking embarrassed. Thanks to all for the help...
Chris, (and to all who tried in earnest to penetrate my extra thick cranium)
The following Universal loadline calculator for vacuum tubes - Vacuum Tube Amplifiers - DIY
tied EVERYTHING up lol..
Now, I get it. And, re-reading what was written, well.. I'm pretty much freaking embarrassed. Thanks to all for the help...
Great links!! Thank you...
Only in the 50's did folks mix learning with almost a comic book like layout..
Think Im going to load up the laser printer lol....
i am building a 300b for a friend, will use the 12gn7 fatboy as voltage amp in a pentode ode, thinking 400v plate and 60ma plate current, 3.5k plate load...