The Blues Junior is a tube guitar amplifier introduced in 1995 by the Fender company.
It is aimed at achieving the warm, tube-driven tone common in many styles of American blues and blues rock dating back to the 1950s, while remaining both portable and affordable.
The Fender Blues Junior is most similar to the Fender Blues Deluxe, which adds a "drive" channel, an effects loop, and uses 6L6GC output tubes for 40 watts of rated output.
Another method of dating a tweed Fender Champ is by serial number.
On my 1959 tweed Champ amplifier, the serial number is located right in front of the fuse cap.
The switch to the cream-colored boards reflects the change in where the amps were manufactured, from USA to Mexico.
The cream-colored board is laid out entirely differently from the green board. The older amps tend to sound darker, while the new ones are brighter with more emphasis on treble tones.
Fender introduced the Blues Junior in 1995 and has revised and updated the amp periodically since then.
The Blues Junior history can be divided into two major categories: the early amps with green circuit boards and the later ones with cream-colored boards.
It is stamped into the chrome chassis with a white letter “C” (for Champ) and the serial number, also in white.
As you can see from the photo below, the serial number of my amp is C 09556.
The codes can be handwritten, which can occasionally make the letters hard to decipher. There is no reliable way to date 2003–2005 amps other than to ask Fender customer support to look up the date from the serial number.
Amps made in 2006 have a small metal "Fender 60th Anniversary" button on the back plate. In 2010 Fender updated their line of hot rod model amps and released the "Blues Junior III," adding many physical changes to the standard black tolex model.
The "Blonde" and "Brown Tolex" Blues Juniors feature traditional Fender Tolex upholstery in their respective colors, while the Sunburst Ash edition features an ash cabinet with a sunburst stain.