12V overdrive question

[Colas LeGrippa]

I just finished another tube overdrive stompbox and I was very surprised to see that a 12AU7 yields out more power than a 12AX7. Someone can tell me why ?
Here ls the schematics  I just drawn

[Colas LeGrippa]

More pics

[Colas LeGrippa]

Regulated power supply

[Colas LeGrippa]

Omg, not exactly the same dimensions as the original one.....😀

[shooter]

a 12AU7 yields out more power than a 12AX7. Someone can tell me why ?

Cuz the datasheet says so
1.2W pd ax
2.75W pd au
If you mean louder, can't help ya there 

[Colas LeGrippa]

Much louder, by 50 percent..I did mot think a low voltage stompbox would scrape off the paint from my walls like this one does.

[PRR]

> surprised to see that a 12AU7 yields out more power than a 12AX7

AU conducts better. Passes more current. At a mere 12V, that counts for a LOT.

The old-guy guide was to run a B+ at least as high as the tube Mu. Otherwise the bias is unstable. 12AX7 should have 100V supply. 12AU7 is from a family which often found itself on a 22.5V battery. The guide hides some assumptions, and late Tung-Sol could do some better. But good to keep in mind.

[Colas LeGrippa]

I'll  keep that in mind that' s for sure.
Thanks for explanations.


Coppola.