So my Fender Blues Jr has begun to hiss (I am guessing it's time to get new tubes).

It uses 3 12AX7 and 2 E 84 tubes. What are the differences in different brands of tubes, does it matter much? I found them for $10 online, do they need to be matched and have balanced triodes or not?

If I tried to do this myself, do I just unscrew the old tubes and screw in the new ones? How does biasing work for the blues jr and would anyone have any suggestions on how I could go about biasing the amp? If I bias it wrong or mess up somehow what will happen, tubes won't last as long? Worse Case?

Also, the amp is relatively loud, is this due to the biasing or the tubes or what, how could I fix that a bit?

There is only one guy in town that does this, and because of that he is a dick and won't even give me price estimates for the work, so I am kind of determined to do it myself.

Edit: How can I tell the year of this amp, it isn't evident anywhere on it as far as I can see.
Standard Fender Telecaster
Fender Blues Jr
Last edited by zipppy2006 at May 24, 2008,
Read this . That gives a description of some popular tube brands. I believe that the biasing on the Blues Jr. is fixed so you can't change it. Not sure though. To replace the tubes, just pull them straight out of the socket and put the new ones in. It takes 10 minutes tops.

And for the date,
Quote by Random Site

All Fender amplifiers, manufactured after 1989 include a date code on the amplifier.
This code is located on the "QA" (Quality Assurance) sticker, which may be found on the back of the amp chassis. The sticker is a Black and Silver label, which contains several lines for "sign-offs" at the completion of sound and electrical tests, where applicable. The last line will have 2 letters of the alphabet either printed or written by hand. These letters are the production date code for the amplifier. The first letter refers to the year, and the second letter refers to the month of manufacture. The codes are:
1990-A 1991-B 1992-C 1993-D 1994-E 1995-F 1996-G 1997-H 1998-I
1999-J 2000-K 2001-L 2002-M 2003-N 2004-O 2005-P 2006-
Last edited by Geartrigger at May 24, 2008,
cool, anyone know how to tell the year of these things?
Standard Fender Telecaster
Fender Blues Jr
I retubed my Twin with the Fender tubes that don't need rebiasing. They work fine.
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