why concern yourself with phase shift? that is a least concern imho...
how many gains? how many gain stages do you need? can you do it in one stage?
what are you trying to do? a power amp or a line stage with balanced outputs?
settle these first and worry about phase shift later...or else do direct coupling between stages if you know how...
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1. 90 degrees out of phase?
Loudspeakers, not amplifiers.
That sounds like a single pole crossover, 6dB/Octave:
A series inductor for the woofer(45 degrees Lag [-]),
And a series capacitor for the tweeter (45 degrees Lead [+]).
+45 and - 45 is 90 degrees differential.
Each speaker is at 0.707 of the voltage (1/2 power; -3dB) at the crossover frequency.
What a great phase and power relationship (simple too).
For a more refined crossover:
Try the Linkwitz - Riley 24dB/Octave
Do not complain about the complexity; that kind of performance justifies it.
Or, for a preamp that has two outputs that are 90 degrees phase shifted, one output a low pass, and one output a high pass . . .
We have electronic single pole crossover filters for Bi-Amping to mono-blocks and from there to a woofer and a tweeter. The speaker system does not need the passive inductor and capacitor mentioned above. You need 2 power amplifiers for Left channel, and 2 power amplifiers for right channel.
2. Push pull output tubes are 180 degrees out of phase.
So are phase inverters, balanced stages, etc.
Loudspeakers, not amplifiers.
That sounds like a single pole crossover, 6dB/Octave:
A series inductor for the woofer(45 degrees Lag [-]),
And a series capacitor for the tweeter (45 degrees Lead [+]).
+45 and - 45 is 90 degrees differential.
Each speaker is at 0.707 of the voltage (1/2 power; -3dB) at the crossover frequency.
What a great phase and power relationship (simple too).
For a more refined crossover:
Try the Linkwitz - Riley 24dB/Octave
Do not complain about the complexity; that kind of performance justifies it.
Or, for a preamp that has two outputs that are 90 degrees phase shifted, one output a low pass, and one output a high pass . . .
We have electronic single pole crossover filters for Bi-Amping to mono-blocks and from there to a woofer and a tweeter. The speaker system does not need the passive inductor and capacitor mentioned above. You need 2 power amplifiers for Left channel, and 2 power amplifiers for right channel.
2. Push pull output tubes are 180 degrees out of phase.
So are phase inverters, balanced stages, etc.
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Why concern myself with phase change is a valid question.
Every thing that I have learned in my life AND retained was because i asked a question.. out loud or to my self...
While some know so much they don't remember when it was all a mystery.. the pursuit of knowledge can sometimes be best served in these pages... you cant ask a book a question lol...
an earlier response reminded me that most audio signal levels with correctly chosen caps, the effect of phase wasn't a concern.
I actually admonished myself for not simply hooking up a signal through a coupling cap and actually measuring the phase... but with a full time gig, side gig and responsibilities.. cut myself slack 🙂
After these posts, and searching books, the web and 300b amp schematics, I still see no explanations this type of stage for amplification. The white cathode follower does not have the grid directly coupled to the plate and b++ of the previous stage. One of the twin triodes cathode being tied to the plate of the tubes section..
Quite along time ago, someone at one of the forums commented the following with respect to my amps schematic.. "C7 is part of the SRPP/cascode arrangement of the 6SN7, blocking DC to the lower grid, an arrangement I'm not familiar with."
Im not alone lol...
1st, i truly want to understand what its doing and how. I have my guess based on what I have learned about triodes in general but would love to confirm...
2nd I find it odd that it could be so unique.. tube technology has been around for quite a while, im sure almost nothing new is or can be done with tubes and passives alone... that said im certain someone will say its used all the time and give a bunch of examples (I hope!!!)
Every thing that I have learned in my life AND retained was because i asked a question.. out loud or to my self...
While some know so much they don't remember when it was all a mystery.. the pursuit of knowledge can sometimes be best served in these pages... you cant ask a book a question lol...
an earlier response reminded me that most audio signal levels with correctly chosen caps, the effect of phase wasn't a concern.
I actually admonished myself for not simply hooking up a signal through a coupling cap and actually measuring the phase... but with a full time gig, side gig and responsibilities.. cut myself slack 🙂
After these posts, and searching books, the web and 300b amp schematics, I still see no explanations this type of stage for amplification. The white cathode follower does not have the grid directly coupled to the plate and b++ of the previous stage. One of the twin triodes cathode being tied to the plate of the tubes section..
Quite along time ago, someone at one of the forums commented the following with respect to my amps schematic.. "C7 is part of the SRPP/cascode arrangement of the 6SN7, blocking DC to the lower grid, an arrangement I'm not familiar with."
Im not alone lol...
1st, i truly want to understand what its doing and how. I have my guess based on what I have learned about triodes in general but would love to confirm...
2nd I find it odd that it could be so unique.. tube technology has been around for quite a while, im sure almost nothing new is or can be done with tubes and passives alone... that said im certain someone will say its used all the time and give a bunch of examples (I hope!!!)
The White cathode follower is a self-driven push-pull buffer stage, with low output impedance.
Original patent from the 1940s:
https://www.pearl-hifi.com/06_Lit_A...04/Sec_19/991_White_Follower_Optimization.pdf
Original patent from the 1940s:
https://www.pearl-hifi.com/06_Lit_A...04/Sec_19/991_White_Follower_Optimization.pdf
how about first learning how each stage in a tube amp works,
the dc biasing of any circuit is supposed to be the easy part,
the ac response is the hard part, first things first..
you sound to me like you are confused...
you are trying to gobble up knowledge all at once, try one by one..
gain and phase go together, and phase is not constant with frequency, so that at high frequencies, compensation maybe required for stability..
the dc biasing of any circuit is supposed to be the easy part,
the ac response is the hard part, first things first..
you sound to me like you are confused...
you are trying to gobble up knowledge all at once, try one by one..
gain and phase go together, and phase is not constant with frequency, so that at high frequencies, compensation maybe required for stability..
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Passive circuits are always taught first, for very good reasons. Only after having understanding at that level
can one hope to understand active circuits.
can one hope to understand active circuits.
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So i have a fundamental knowledge of triode basics. At whatever bias you choose, and without a signal at the grid, the tube is hopefully conducting in the middle of its range inbetween cutoff and saturation while the plate is at a certain voltage. A small signal at the grid increases current through the plate to cathode depending on that grid voltage. The tube amplifys this using dc current from plate to cathode and the coupling cap between the plate resistor and plate blocks the dc, allowing only the amplified signal to the next stage.
What gets me here is the grid on the first stage is directly coupled to b+. No coupling cap. Im guessing the capacitance of both stages acts as a coupling cap.
What im fuzzy about is the cathode on pin6 is coupled/driving the plate on pin 2. From my mind bending meditation i can only assume there is some push pull action happening here, which might only be increasing voltage instead of current (or visa versa)
Alot of folks are suggesting i learn the basics instead of telling me whats going on themselves.. isnt the term used today gas lighting lol?? Im not suggesting anyone who says learn the fundamentals is wrong. Im trying to do exactly that lol...
Lastly, not everyone learns the same way. Without going sideways on this thread, many folks dont even think the same way. That said my approach to understanding anything may not be typical but has served me well at least in half of my life lol...
What gets me here is the grid on the first stage is directly coupled to b+. No coupling cap. Im guessing the capacitance of both stages acts as a coupling cap.
What im fuzzy about is the cathode on pin6 is coupled/driving the plate on pin 2. From my mind bending meditation i can only assume there is some push pull action happening here, which might only be increasing voltage instead of current (or visa versa)
Alot of folks are suggesting i learn the basics instead of telling me whats going on themselves.. isnt the term used today gas lighting lol?? Im not suggesting anyone who says learn the fundamentals is wrong. Im trying to do exactly that lol...
Lastly, not everyone learns the same way. Without going sideways on this thread, many folks dont even think the same way. That said my approach to understanding anything may not be typical but has served me well at least in half of my life lol...
I will take a shot.
First, assume that there is no significant phase shift across any of the capacitors. They are simply DC blocking coupling caps.
Second, show the load connected to the junction of the bottom plate of the lower tube and the cathode of the upper tube.
Think about how current can be delivered to the load.
The upper tube delivers load current in a cathode follower like action. Because its plate is not connected directly to a supply, but through a resistor it also behave as an amplifier. When driving the load with current to increase voltage, current in the plate resistor also increases. This causes the upper tube plate voltage to decrease.
The upper tube plate signal is then coupled to the grid of the lower tube. This signal decreases the lower tube plate current and allows (in the limit) for all the upper tube cathode current to flow into the load instead of being partially diverted through the lower tube.
Reverse the signal direction, the upper tube cuts off, and the lower tube turns on. Now current is pulled out of the load instead.
First, assume that there is no significant phase shift across any of the capacitors. They are simply DC blocking coupling caps.
Second, show the load connected to the junction of the bottom plate of the lower tube and the cathode of the upper tube.
Think about how current can be delivered to the load.
The upper tube delivers load current in a cathode follower like action. Because its plate is not connected directly to a supply, but through a resistor it also behave as an amplifier. When driving the load with current to increase voltage, current in the plate resistor also increases. This causes the upper tube plate voltage to decrease.
The upper tube plate signal is then coupled to the grid of the lower tube. This signal decreases the lower tube plate current and allows (in the limit) for all the upper tube cathode current to flow into the load instead of being partially diverted through the lower tube.
Reverse the signal direction, the upper tube cuts off, and the lower tube turns on. Now current is pulled out of the load instead.
This White Cathode Follower has unity gain , the top tube is the cathode follower and the lower tube is like an active resistor . The top plate low value resistor is just for producing a voltage for driving the lower tube , which of course in inverted from input like in a push-pull self split (inverting) stage ... but with no voltage gain .
Capacitors don't play any role in the phase invertion , is just the normal 180dgr phase shift from grid to plate in a tube
Capacitors don't play any role in the phase invertion , is just the normal 180dgr phase shift from grid to plate in a tube
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if you post a complete picture or a circuit, then we can discuss issues to your heart's content...
it is hard to read minds in front of a pc monitor...
the schematics is our language that everyone can understand...
There's a closely related thread which boiled down to a discussion on the difference between phase VS polarity shift as both are causally used interchangeably by many.
https://www.diyaudio.com/community/threads/single-ended-phase-clarification.395503/
https://www.diyaudio.com/community/threads/single-ended-phase-clarification.395503/
Boom! SRPP .. Ultima did it..
See tubecad has a writeup on it...
Also glad to see that my meditation was worth it, it behaves like a class a push pull amp increasing voltage for driving the 300b..
Phase versus Polarity,
Most people do not understand the difference, as evidenced by the fact that we are already at Post # 37, and some of you still do not get it.
Just go study "Group Delay".
When you can properly understand Group Delay, then come back to this thread.
(if you thought phase and polarity was difficult to understand, how about Group Delay?)
I bet that a lot of the Posters and Readers at the Loudspeakers Multi-Way Threads understand Group Delay.
Now, Multi-Way loudspeakers is a great application of the Tri-Concepts:
Phase
Polarity
Group Delay
Have Fun!
Most people do not understand the difference, as evidenced by the fact that we are already at Post # 37, and some of you still do not get it.
Just go study "Group Delay".
When you can properly understand Group Delay, then come back to this thread.
(if you thought phase and polarity was difficult to understand, how about Group Delay?)
I bet that a lot of the Posters and Readers at the Loudspeakers Multi-Way Threads understand Group Delay.
Now, Multi-Way loudspeakers is a great application of the Tri-Concepts:
Phase
Polarity
Group Delay
Have Fun!
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I am reminded of a high frequency application.
A ground plane is covered with an insulating Substrate.
A strip line conductor is placed on top of the same Substrate.
A square wave is applied to the line conductor and ground plane.
Most of the signal power goes down between the strip line and ground plane.
It has a particular velocity, it is less than the speed of light.
Some of the signal power goes down between the strip line and the capacity field of the air around the top of the strip line.
It has a particular velocity, it is almost the speed of light.
As a result, the first part of the square wave is from the strip line / air path.
It arrives Before the strip line / substrate square wave arrives.
What a distorted square wave we get.
Many digital communication circuits on the board (substrate) have to do battle with this distortion of the square wave.
(is it a "ONE", or a "Zero", ??? You Better wait until the air path distortion is over, to see which it is).
A ground plane is covered with an insulating Substrate.
A strip line conductor is placed on top of the same Substrate.
A square wave is applied to the line conductor and ground plane.
Most of the signal power goes down between the strip line and ground plane.
It has a particular velocity, it is less than the speed of light.
Some of the signal power goes down between the strip line and the capacity field of the air around the top of the strip line.
It has a particular velocity, it is almost the speed of light.
As a result, the first part of the square wave is from the strip line / air path.
It arrives Before the strip line / substrate square wave arrives.
What a distorted square wave we get.
Many digital communication circuits on the board (substrate) have to do battle with this distortion of the square wave.
(is it a "ONE", or a "Zero", ??? You Better wait until the air path distortion is over, to see which it is).
Back in the Usenet days there was a guy (of course it was a guy - females rarely issue death threats over definitions of words) who would go DefCon if somebody used the term "group delay". He would insist it be called "phase noise". I never understood and he never explained this choice. Maybe he was the Unibomber?
All good fortune,
Chris
All good fortune,
Chris
the simplest way is to give your driver tube more plate voltage, and more plate current to drive the miller caps at higher frequencies...