Hi!
This is my first post here, I came asking to review the amp I'm designing:
I triode-strapped the tube so it would be easier to wind the transformer (lower primary impeadance=less turns). In the attavhments you can see diffrent feedback methods.
This is my first post here, I came asking to review the amp I'm designing:
I triode-strapped the tube so it would be easier to wind the transformer (lower primary impeadance=less turns). In the attavhments you can see diffrent feedback methods.
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Okay, got it!
View attachment cathodefeedback.pdf
View attachment grid_feedback.pdf
View attachment no_feedback.pdf
View attachment schem.pdf
BTW. It seems that all of my posts have to be approved by a mod before they show up? Is it because I'm a new user? How to get rid of it?
View attachment cathodefeedback.pdf
View attachment grid_feedback.pdf
View attachment no_feedback.pdf
View attachment schem.pdf
BTW. It seems that all of my posts have to be approved by a mod before they show up? Is it because I'm a new user? How to get rid of it?
I can now access your pdfs and will take a look at them later.
Moderator approval will stop after you've made a few legitimate posts.
Re 'asking to review the amp' - do you have any specific questions you would like to ask?
Moderator approval will stop after you've made a few legitimate posts.
Re 'asking to review the amp' - do you have any specific questions you would like to ask?
I shall leave it to the valve experts to comment on your cathode and grid feedback loops.
The cathode feedback loop on the single ended ECL82 amplifier that I built certainly differs from yours.
The cathode feedback loop on the single ended ECL82 amplifier that I built certainly differs from yours.
Hi Gamebuster!
I suggest you do a bit more research on how global negative feedback (GNFB) works.
Essentially, you have to feed a small fraction of the output voltage back to the input. This is done using a voltage divider consisting of two resistors. You have included one of these resistors in your circuit, but not the other one.
See Figure 31 in the link below where R1 and R2 form the voltage divider. (Note also that the capacitor Csn is in parallel with R1 and not in series as shown in your circuit.)
4.4 Global Negative Feedback in a vacuum tube amplifier - Vacuum Tube Amplifiers - DIY
I suggest you do a bit more research on how global negative feedback (GNFB) works.
Essentially, you have to feed a small fraction of the output voltage back to the input. This is done using a voltage divider consisting of two resistors. You have included one of these resistors in your circuit, but not the other one.
See Figure 31 in the link below where R1 and R2 form the voltage divider. (Note also that the capacitor Csn is in parallel with R1 and not in series as shown in your circuit.)
4.4 Global Negative Feedback in a vacuum tube amplifier - Vacuum Tube Amplifiers - DIY
Oh, now I see, you put a aditional resistor between the cathode bias and ground, you apply the feedback on that point by a parralel resistor-capacitor combo.
Now a transformer question:
How may turns on the primary of a 1.44 sqr cm transformer core to steer a 8 ohm speaker off the secondary? 33 times the sqrt of primary impedance?
BTW. I love this forum, it's much friendlier than stack exchange!
Now a transformer question:
How may turns on the primary of a 1.44 sqr cm transformer core to steer a 8 ohm speaker off the secondary? 33 times the sqrt of primary impedance?
BTW. I love this forum, it's much friendlier than stack exchange!
Global feedback seems to be so confusing to a number of people. For the most part, I do not use GNF, but when I do, it is only for 2 stages.
I do use 2 other kinds of negative feedback: Triode wiring a Pentode or Beam Power tube. Ultra Linear output.
I do use 2 other kinds of negative feedback: Triode wiring a Pentode or Beam Power tube. Ultra Linear output.
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