TP24 Power Transformer
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.
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. There’s no particular reason to choose a 5881 over a 6L6GC, unless you like the sweet tone of a particular tube, such as the Tung-Sol reissue 5881. The 6L6 delivers more bass and more clean headroom:
When paired with the TO26 output transformer, the TP24 can drive a pair of 6L6s to a clean 30 watts, with all of the effortless, big-plate sound you expect from a 6L6 amp, but still in the Blues Junior’s convenient form. We provide the TP24 with leads trimmed for the Blues Junior and high-quality, double-crimped push-on connectors for easy installation.
With EL84s or 6V6s and either the TO20 or TO22 output transformer, you’ll hear additional clean headroom and the additional punch you get from having all the current on tap that the tubes can use. There is no sag.
New video: Here’s a link to a demonstration of the TP24 with EL84s. The higher voltage brings out the glassy nature of the EL84s, which the Blues Junior otherwise masks. The presence and sparkle controls help you dial back if you find it a bit too aggressive:
New! The bias board gives you proper bias regulation for all octal tubes with the higher voltages produced by the TP24. It, and the basic mods kit, are essential for proper operation of the TP24.