Hi friends! I was cleaning and discovered that i have 145 volts DC regulated power supply and bunch of 6J1 tubes. I think i can find 6 or 12 volts supply, so i am thinking about building something. Buffer or preamp. Sure i searched, but i would like simple verified schematics someone tested and is happy with it. Not that crappy 'fever 6j1' which circulates around.
Wonder if you ended up testing out that buffer circuit?
I've get some GE tubes that I want to use for something interesting. Did you see any other hopeful candidates?
I've get some GE tubes that I want to use for something interesting. Did you see any other hopeful candidates?
I have not done anything yet, I was hoping to receive some feedback, or some verified schematics. Oh well. I will put it together in a day or two.
Just do it.
Nothing is going to break, or be bad.
I don't think one could find a more vanilla 0 dB buffer, than this.
You don't even need a 'case' for it, to try.
Just use alligator-clips on the bend.
And set up the power supply bit on a tiny breadboard.
Don't forget that the 10 kΩ resistor in the power supply is going to get hot. Use a 5 watt part, or a string of lower-watt, lower-Ω parts to make the 10 kΩ.
⋅-=≡ GoatGuy ✓ ≡=-⋅
Nothing is going to break, or be bad.
I don't think one could find a more vanilla 0 dB buffer, than this.
You don't even need a 'case' for it, to try.
Just use alligator-clips on the bend.
And set up the power supply bit on a tiny breadboard.
Don't forget that the 10 kΩ resistor in the power supply is going to get hot. Use a 5 watt part, or a string of lower-watt, lower-Ω parts to make the 10 kΩ.
⋅-=≡ GoatGuy ✓ ≡=-⋅
Minor weird think happened when i put volume pot infront of it. I got nice 250k alps pot, so i put it on input, and when its in zero volume position, there is small buzz. When i turn it up a little, it goes away. No buzz all the way up to full volume. What is going on?
One thing i do not understand, that schematics claims there should be negative 1.9 volts on the grid. Negative. Where does one generate negative volts? Its only powered by asymetrical power supply. I measure above fifty volts on the grid, positive off course.
Why do they expect grid to get negative? Towards what reference? I measure only agaist the ground.
Why do they expect grid to get negative? Towards what reference? I measure only agaist the ground.
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in the schematic you started with, the second grid is connected to the anode which is a fairly traditional way to turn a pentode into a triode, by feeding back the signal from the anode to the second grid
however when you are using it as a cathode follower the signal is now on the cathode and if you want to use this in Triode mode you need a way to feedback the signal from the cathode to the second grid - I have attached an example from Broskie of how to do it
however when you are using it as a cathode follower the signal is now on the cathode and if you want to use this in Triode mode you need a way to feedback the signal from the cathode to the second grid - I have attached an example from Broskie of how to do it
Attachments
My understanding is that grid voltage is measured between the grid and cathode.
The negative is caused by the pure magic happening inside the tube.
The negative is caused by the pure magic happening inside the tube.
ok, that makes sense, i got -2volts there, thanks
how about that weird pot behavior at zero volume
i replaced with another pot, the same
looks like I need to put the pot on output
how about that weird pot behavior at zero volume
i replaced with another pot, the same
looks like I need to put the pot on output
i am starting to get frustrated with this
i put volume pot on output and it does not like it either, there is buzz at certain positions
when i remove the pot, all is good, nice sound, no hum or buzz
weird
i am going to give it a rest, I got other projects to finish
i put volume pot on output and it does not like it either, there is buzz at certain positions
when i remove the pot, all is good, nice sound, no hum or buzz
weird
i am going to give it a rest, I got other projects to finish
just found one defective leaky capacitor in filament (I use dc on filament to eliminate hum) and all is good
now to put it in the box!
now to put it in the box!
