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Originally Posted by ts31966
I have found exactly the same thing Marty. V1 and V2 makes the amps tone. The rest of the tubes just need to be quiet. But the 5150 is set up a little differently than most amps. Channel 1 and 2 are similar but channel 3 has its own voicing.
I haven't bought a tube tester. I need to learn more. I want the amplitrex but I don't know if it is worth it for me.
Tell me this Marty, I have this tube that sounds great but on channel 3 with the gain maxed out and the guitar volume maxed out the tube starts freaking out. It makes all kinds of weird noises and the distortion from the tube is all over the place. The tube is not microphonic. The tube is a black plate brimar labeled raytheon.
Also Marty what do you know about 12dt7's. I have a whole bunch of black plate raytheons. They sound great for channel 1 and 2 but channel 3 doesn't have as much gain with them in the v1 and v2 position.
I am thinking that both triodes do not have the same gain in this tube and this is lowering the output on channel 3. I am going to have to call fender Monday about that.
Most of my tubes are old. They sound great but I think they need to burn in. Have you guys had experience with tubes settling once you leave them powered on for awhile?
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Well the EVH's are super high gain heads and they have a fairly complicated preamp section. How do they split the tubes between channels 1, 2 and 3?
About the Brimar. It almost sounds like a rattling plate. The plate are welded to a post and if one (or some) of the welds come loose, the plate will move microscopically. However, it could also be that when the controls are fully maxed out, the tube is suffering from threshold distortion. Apparently, you can stick other tubes in there and max them out and there isn't any problems. Is this correct?
12DT7's a rare and a superior sub for any 12AX7. Both sides are rated at 100mu, the same as a 12AX7. However, the rP (plate resistance) is different than that of a 12AX7. A 12DW7 is the one that is lopsided. It is 100mu on triode one and 17 on triode two. This is basically 1/2 of a 12AX7 and 1/2 of a 12AU7. You are not going to realize much gain in V3. This is probably your tone stack section (it is for a Marshall). You will want a tube in here that adds flavor to the tone controls and is somewhat balanced. It doesn't have to be perfect and it doesn't have to be a high gain tube. Just a decent one. (Those 12DT7's are expensive. Did you get them a long time ago? I haven't seen any for sale for a long time.)
As far as how the tubes work in Channel Three? Well, if the tubes are kicking butt in Channel 1 and 2, they should do the same in Channel 3. Yes, you may want to consult Fender on that. Hopefully they won't frown about you changing out the tubes. You know, warranty issues???
As far as old tubes go. I have found that an old good tube will get a little stronger the longer it is on. Not much but some. I have taken readings on a tube and then left it intentionally in the tester for an hour and then retested it. Some tubes read the same and some read a little stronger.
Hope this helps. Marty