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Old 15th May 2013, 12:54 AM   #1
RevMen is offline RevMen  United States
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Default 6922 preamp idea

I would like to build a line stage preamp using a pair of 6922's and as few parts as possible. This is my second attempt at creating a circuit like this. I think I've got it, but of course it would be wise to get some more knowledgeable people to view it before I build it and subject it to high voltage.

So does this make sense, what I've done? I've attached the schematic and the load lines for both stages.
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File Type: png 6922 pre schem 1.PNG (18.6 KB, 230 views)
File Type: png GS OP 1.png (344.5 KB, 224 views)
File Type: png CF OP 1.png (346.8 KB, 187 views)
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Old 15th May 2013, 01:10 AM   #2
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The grid voltage is usually lower than the cathode.
As you show loadlines with negative grid bias, I'm
assuming you knew what you were doing and must
have mixed up the drawing.
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Old 15th May 2013, 02:02 AM   #3
RevMen is offline RevMen  United States
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Rookie mistake. Thanks for pointing that out.

121V should be 111V. That actually makes 27k the exact right value instead of the closest value, so that's good.

I've attached the fixed schematic.
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Old 15th May 2013, 02:16 AM   #4
AJT is offline AJT  Philippines
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you can read upon Broskie's CCDA......CCDA: constant-current-draw amplifier

i do no think you really need that high a B+, from 100 to 200 volts is plenty....better to keep the plate voltage at 90 volts max...
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Old 15th May 2013, 05:16 AM   #5
Bonsai is offline Bonsai  Taiwan
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Should this not be in the tubes section?
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Amplifier Design and Construction for MUSIC! http://hifisonix.com/
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Old 15th May 2013, 09:54 AM   #6
AJT is offline AJT  Philippines
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thread moved....
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Old 15th May 2013, 10:37 AM   #7
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I would replace the 16K resistor with a DN2540 configured as a CCS.

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