Can I mod this circuit to use 6922 tubes?

[DirkD]

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]

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

 

[DirkD]

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

 

[SY]

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]

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.