Difference between 12AU7 and 12AU7A


Anyone out there know what the difference between these two tubes is? All 9 pin mini dual triodes suppossedly can be rolled into the voltage amp stage of my Llano Trinity 300.
128x128swampwalker
Iasi- Don't try that sub unless you have a Llano amp, or get an OK from a tube expert. Llano amps have a unique design that allows this to substitution.
well, i'm new to tubes, but i have a question...what is the difference between 12AU7 and 12AX7?...can i replace the U with the X?...thanx
Hi,

Saw your post and was wondering what tubes are you using in your Trinity's. What do you like about what you are using? Have you used any others?

I'm looking to put new tubes into my Trinitiy's and know next to nothing about the choices. And Randy took the tube help sheet off the website. Any thoughts appreciated.

Keep up the good work in the wetlands.

-- Bob
What are you using in your Trinity's. What do you like about what you are using? Have you used any others?

I'm looking to put new tubes into my Trinitiy's and know next to nothing about the choices. And Randy took the tube help sheet off the website.
Both tubes are electrically identical. The "A" is a slightly more rugged construction which results in lower output microphonics. The "A" designation is more for application purposes, designed to be used in a series heater circuit of tv's, radios and other older electronics. But for modern audio, the 12V circuits are not in series and therefore should make no difference which designation you use. As for sound, tubes are different and I cannot really say if the "A" is better/worse for a particular application for a given tube.