phase inverter, tube type and gain.

[Andy Le Blanc]

I was playing with the Idea of using a 12au7 as LTCC PI, and was curios if anybody had done so,.

pretty familiar with 12ax7 and 12at7 in a fender circuit and values, but I'm just getting around to 12au7, and 12ay7, even 5751 in that portion of the gain structure,
wondering if others had already played around there.

[Phil_S]

Well, Andy, as you know all of this is really over my head, but I am interested anyway. I am thinking that for a CC PI, the 12AU7 has got to be a great choice. It is the king of current in common guitar tubes. So, I did a quick search and turned up this example of a 12AY7 and thought you might want to see it, as the site appears to be guitar oriented (rather than audiophool), though this particular one seems to be more audio oriented. http://www.lwharpamps.com/stereo.html

[roberto]

The classical 12Asomething7 swap it's something everyone has done, but I think you mean experimentation on good polarization of PI with those tubes.

I've experimented something with 10mA like tubes, but never found a configuration I liked. I'm going more and more into 12ax7 (I want my EI tubes back!) with few feedback (around 100k on 4k7, 4ohm tap), so something going the opposite.