Can I mod this circuit to use 6922 tubes?

DirkD · 23rd September 2005, 11:17 AM

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

reinhard · 23rd September 2005, 11:34 AM

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

DirkD · 23rd September 2005, 11:34 AM

B.T.W. plaese ignore the phono stage. I am only interested in the line stage. Here is the component list.

SY · 23rd September 2005, 11:40 AM

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...

amperex · 23rd September 2005, 07:00 PM

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.

23rd September 2005, 11:34 AM	#2
reinhard diyAudio Member Join Date: Dec 2000 Location: Germany	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

23rd September 2005, 11:40 AM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	You can use the same topology, but going from a 12A7 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... __________________ “Listening to records is like ***ing a picture of Brigitte Bardot.” - Sergiu Celibidache

23rd September 2005, 07:00 PM	#5
amperex diyAudio Member Join Date: Feb 2005 Location: MI	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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