Difference between 12AU7 and 12AU7A

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.