Bugera 333XL 212 Combo Tube Questions

[Muskratt]

I have read on the Bugeras 333xl tubes that they are propriatory per socket.
I have four 12AX7 Sockets all Bugera's Premium Tubes

1=12AX7A
2=12AX7B
3=12AX7B
4=12AX7C

And the Power Tubes are Bugeras Premium EL34's Matched.

So my Question is in the number 2, 3 and 4th Socket do I have to use those exact tubes here or does anyone know of some alternates/equivalent tubes?




I know the ECC is the European Designation. I been around here and their looking but most stray off topic rather then answering the question directly..
So how about some input..

Thank You!

[Enzo]

Oh, they are claiming to have tested and sorted the preamp tubes, and selected them for various characteristics. However, a 12AX7 is still a 12AX7, so you can use ANY 12AX7 in any of those sockets. SOme tubes will be more microphonic than others. It will matter most in the first socket. If you install a tube and it is overly microphonic, then try a different one in the socket and move the noisy one to a later socket. A tube that is overly sensitive in the first socket will probably work just fine in the phase inverter position.

[Muskratt]

Hey Enzo,

Thanks for getting back so soon. OK I just wanted to try to make REAL Sure of this. I can understand that the Pre in number one can be more Microphonic, so that is easy to understand.
Now the next thing on the Phase inverter tube is there any specifics for this socket. By what your saying above is just placing the more sensitive down the line doesn't effect the sound as bad as the first tube.
So now I should be able to make better sense of the tube sets that I can buy for them.

Anyone else with Bugeras care to chime in do so..

[Enzo]

Nothing in particular about the phase inverter, I just picked it as a place where a tube that was too microphonic for the first stage might work perfectly well there. The phase inverter is late in the amp, the signal levels are very large compared to the first stage, and it is not a high gain stage either. So it just doesn;t much care about microphonics unless they are really bad.

And be aware that these concerns are universal, and not specific to Bugera amps. I'd tell you the same thing if we were discussing a Fender Hot Rod DeVille.

[Muskratt]

Thanks Again Enzo,

That makes it easy to understand. Thought i would post this as a topic for any other 333/333XL fans out there. It really sounds as if the Bugera company has a recommendation on what preferred tubs they want in certain sockets rather then letting the owner decide the tube brand and tone characteristics.
So in essence I could throw all three of my MESA 12AX7A tubes in there to see what it yields.

Interesting...

[Enzo]

Nothing cosmic, they want the lowest noise tubes in the first sockets. That way their amplifiers are the least noisy they can be.

[Muskratt]

Awesome, Now if I wasn't below poverty and could afford a few new tubes and a BIAS Probe I could get into the next stage of maintaining my gear.
Thx Enzo!

Your up for a Golden Tube Award!