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Old 16th February 2013, 03:22 PM   #11
gabdx is offline gabdx  Canada
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I will try this out before going to transformer splitter...

I don't know which way to take 1, 2, 3 and the need for the capacitor on the grid 2. I learned that I could use feedback from the output transformer and send it to Grid 1 or Grid 2, but I ignore the pro or cons.
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Old 17th February 2013, 05:32 AM   #12
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No CCS will work without some bias voltage.
You should give positive bias to tubes or connect the lower end of the CCS to negative voltage instead of GND.

For example LM317 regulator works fine with some 20 V bias.
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Old 17th February 2013, 12:20 PM   #13
gabdx is offline gabdx  Canada
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Hi, I actually use figure 1 from lm334 with the positive voltage of the cathodes. I know it can be improved with thermal stability (figure 3) and it can oscillate if the stage overloads because not enough cathode potential will exist.
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Old 20th February 2013, 12:36 AM   #14
gabdx is offline gabdx  Canada
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Quote:
Originally Posted by gabdx View Post
I will try this out before going to transformer splitter...

I don't know which way to take 1, 2, 3 and the need for the capacitor on the grid 2. I learned that I could use feedback from the output transformer and send it to Grid 1 or Grid 2, but I ignore the pro or cons.
I will use Grid 2 similar to LEAK amplifiers. Now about the values of resistors I have no clue to give me a start...
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Old 23rd February 2013, 03:28 AM   #15
gabdx is offline gabdx  Canada
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I just don't know for the feedback and values of resistors.

I am figuring out if it needs capacitors because the KT88 are biased individually per grid and it could upset the transformer ability to split the music if there is modulation and different fields.

*** maybe I will abandon this idea and adopt this instead: input -- long tail pair -- capacitors -- KT88
I will just do that without capacitors, 0 caps amplifier (haha 2 transformers) I saw that the transformers allow for indifidual biasing current to circulate in both half without any issues.
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