Can I mod this circuit to use 6922 tubes? - diyAudio
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Old 23rd September 2005, 11:17 AM   #1
DirkD is offline DirkD  South Africa
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Default Can I mod this circuit to use 6922 tubes?

Hi there

I built a clone of the Conrad Johnson PV10A, and was wondering if it would be possible to mod it for use with 6922 tubes.

Regards

Dirk
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Old 23rd September 2005, 11:34 AM   #2
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Default 6922 mod

Yes you can, but that is like a new preamp. you have to change the cathode resistors for proper working, the RIAA must change and so on. The B+ supply is a little bit high for 6922.

Reinhard
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Old 23rd September 2005, 11:34 AM   #3
DirkD is offline DirkD  South Africa
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B.T.W. plaese ignore the phono stage. I am only interested in the line stage. Here is the component list.
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Old 23rd September 2005, 11:40 AM   #4
SY is offline SY  United States
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You can use the same topology, but going from a 12A*7 type to 6922 will involve a complete redesign. All operating points will be different, gain structure will be different, power supply requirements will be different, biasing will be different. Other than that...
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Old 23rd September 2005, 07:00 PM   #5
amperex is offline amperex  United States
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Default Fuzzy schematic

If I see the tubes right, they are 12AU7 to be replaced with 6922. Have you tried Brimar 12AU7 or Amperex 6085? They may outperform the 6922.

Note: 600 ma on the 6085 filaments, should not be a problem with the transformer operating too hot.
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