Billm Audio’s ongoing collaboration with David Allen of Allen Amplification pays off again–a real upgrade power transformer! The new TP24 power transformer fits exactly and addresses a number of Blues Junior modification issues:
More heater power for octal conversions. While it’s not necessary for 6V6 output tubes, it’s essential for getting full power from the 5881 or 6L6GC.
More plate voltage. An additional 25 volts of B+ provides more headroom without exceeding the 400 volt rating of the coupling capacitors.
More reserve power. There’s lots of current on tap for a powerful, effortless sound.
Designed for the Blues Junior’s bridge rectifier power supply and includes the bias/solid state winding.
Cooler running under load, no overload or sag issues, as you would get with the stock PT and 5881s or 6L6s.
Click for larger image.
As you can see, the TP24 has nearly twice as much core as the stock power transformer and has an internal bell end for maximum hum protection. The TP24 benefits any Blues Junior, but it delivers the most with 5881s or 6L6s when paired with the TO26 output transformer.
New! The bias board gives you proper bias regulation for all octal tubes with the higher voltages produced by the TP24.
With the Series III, introduced in September, 2010, Fender implemented a “sparkle mod,” which means that they removed a voicing capacitor, C9 on the cream board, which limited the amp’s high-frequency brightness. The Series III is definitely brighter than previous BJrs, but it can also be harsh and strident, even irritating. The Sparkle Control makes the amount of sparkle reduction adjustable from zero (stock Series III) to the same as the series II, to even darker, like the old green board (1995-2000) Blues Juniors. When you pull up on the knob, it defeats the control and gives you the stock BJr III amount of sparkle. Read more here: Sparkle Control.
Back on September 1, 2010, when the Blues Junior Series III was introduced, I went to Guitar Center and bought the first one they’d been shipped. I promptly took it home and had in pieces on my bench. Fender claims a bunch of improvements, but only two of them affect tone: the “sparkle” mod and the new Lightning Bolt speaker. continue reading…
This brilliant new output transformer, co-developed with Allen Amps’ David Allen, is a breakthrough for the Blues Junior, Pro Junior, Princeton Reverb Reissue, and Super Champ XD. Designed from the ground up to provide big-transformer performance in the least possible space, the TO20 is built by respected US manufacturer Heyboer, fits the stock mounting holes in all of these amps and has the same height as the stock transformer. The “widebody” core is made of premium M6 steel, which has superior magnetic properties, allowing maximum efficiency and power transfer from primary to secondary. The low-profile TO20 outweighs the stock OT by at least half a pound! Continue reading.
New! I finally added some sound files so you can hear what it sounds like.
Or as close as I can figure, given the number of components I’ve ordered over the years, shipping records, etc.
I decided to pull out all the stops on this one. I started with a basic black Blues Junior, the perfect platform for a stealth amp that can blow away some much more expensive hardware.
With 5881s, it puts out 25 watts and sounds awesome!
By popular demand! People have been asking me for years for a standby switch on the Blues Junior, and here it is.
There isn’t room inside the chassis for another switch next to the power switch, even if you relocate the pilot light. Yes, you could cram a cheesy little switch in there, but we’re talking high voltage here, and only a heavy-duty switch will do. Fortunately, Carling, the same company that makes the power switch that’s in your Blues Junior, makes a clever progressive switch. It has three positions: off, standby, on–very logical. In standby, the high voltage supply is cut off. The filament and bias supplies receive power.
Welcome to the new home of the Billm mods for the Fender Blues Junior and other amps. This is the main site; information on my old site, http://home.comcast.net/~machrone/bluesjunior.htm is probably out of date.
This is the 1000th Billm-modded Blues Junior.
There isn’t room inside the chassis for another switch next to the power switch, even if you relocate the pilot light. Yes, you could cram a cheesy little switch in there, but we’re talking high voltage here, and only a heavy-duty switch will do. Fortunately, Carling, the same company that makes the power switch that’s in your Blues Junior, makes a clever progressive switch. It has three positions: off, standby, on–very logical. In standby, the high voltage supply is cut off. The filament and bias supplies receive power.