Replacing 12AX7 with 6922

[amey01]

In short, can it be done? For my preamp, I was told "Yes", but I have doubts. Anyone?

 

[slowGEEZR]

Check this out. It appears the heaters are different...
http://www.diytube.com/phpBB2/viewt...ghlight=&sid=ac0ba2a40dd8e72c9fe05e391b3ea765

 

[amey01]

Check this out. It appears the heaters are different...
http://www.diytube.com/phpBB2/viewt...ghlight=&sid=ac0ba2a40dd8e72c9fe05e391b3ea765

So bad advice I was given there. Thought so. Thanks Steve.

 

[sebrof2000]

Funny you should post this. I have a DIY integrated that uses 6922 for the driver. The original design used 12AX7 but it was modified, so I dropped a pair of 12AX7s in and no sound. I'll probably rewire at some point just for kicks.

 

[risabet]

In short, can it be done? For my preamp, I was told "Yes", but I have doubts. Anyone?

No, different pinouts. The 12AX7 is first, the 6922 is second.

 

[miljac]

12AX7 has a heater 12.3V and the midpoint is at pin 9. 6922 heats with 6.3V and pin 9 is the screen (reduces crosstalk).

Also the tubes have different characteristics and operating points. Once heating issues have been resolved there still remains the problem of surrounding circuitry. Both tubes could work with same resistor values but what is optimal for one tube is not optimal for the other.

I would either leave it "as is" or go to someone who really understands tubes to make the necessary changes. Since you're in Australia and if you really want to do it, you might try to talk to Joe Rasmussen.

Here is the link: http://www.customanalogue.com

 

[amey01]

12AX7 has a heater 12.3V and the midpoint is at pin 9. 6922 heats with 6.3V and pin 9 is the screen (reduces crosstalk).

Also the tubes have different characteristics and operating points. Once heating issues have been resolved there still remains the problem of surrounding circuitry. Both tubes could work with same resistor values but what is optimal for one tube is not optimal for the other.

I would either leave it "as is" or go to someone who really understands tubes to make the necessary changes. Since you're in Australia and if you really want to do it, you might try to talk to Joe Rasmussen.

Here is the link: http://www.customanalogue.com

Thanks for that! I intend to leave it at the 12AX7 for now - I can't believe someone has plainly told me that the 6922 is a suitable replacement!!

Thanks everyone!

 

[risabet]

Thanks for that! I intend to leave it at the 12AX7 for now - I can't believe someone has plainly told me that the 6922 is a suitable replacement!!

Thanks everyone!

In this hobby opinions are like a&^holes! Caveat Emptor

 

[tonepub]

The 6922 is not a replacement for the 12AX7, AU7 or AT7.

The 5751 can be swapped for the 12AX7, though it does have lightly lower gain...

The 6922 can be swapped with 6DJ8 and 7308

You can get a lot of good info at

www.thetubestore.com

Best of luck

 

[amey01]

The 6922 is not a replacement for the 12AX7, AU7 or AT7.

The 5751 can be swapped for the 12AX7, though it does have lightly lower gain...

The 6922 can be swapped with 6DJ8 and 7308

You can get a lot of good info at

www.thetubestore.com

Best of luck

Thanks Jeff!