Posted: Thu Jul 07, 2011 2:54 am Post subject: common input preamp tube question ?
Hello, I am not sure if this is the right place to post but I have just bought a rm100 second hand , the amp has been used a lot but the seller had it retubed not too long ago with some Mullard el34's. I have since then sold the old modules and got 3 new ones ( I play high gain ) but it does not look like he changed the three 12ax7 common input tubes that are in the head on the left side. Do these have a effect on the sound they are pretty old.
To change these do you have to do any bias or is it just a matter of take them out and put new ones in, I dont know a lot about this sort of thing ?
Joined: 17 Nov 2008 Posts: 1337 Location: Bristol, VA
Posted: Thu Jul 07, 2011 6:38 am Post subject:
Pull em out, put new ones in. No biasing required.
The one closest to the guitar input is the input tube. I like a TAD 7025 or Tung Sol 12AX7 here.
After that, is the FX loop buffer. This one doesn't matter too much, but a Tung Sol will work.
The one closest to the power tubes is the phase inverter. This is the last gain stage processing the signal before the power section. I will ALWAYS recommend a nice NOS 5751 in there (Phillips, RCA, GE, etc.). Tung Sol will work though. _________________ RM100M w/ Tung Sol 5881's
Blackface(self modded), Ultra Lead, SL+(out of commission), Ultra XL (self modded)
Vader 2x12 Cab
Edwards E-AL-128 with a Seymour Duncan JB
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum