Another post in a series of legendary tube brands. This time I will go into details of General Electric (GE) Five-Star Brand.
Right out of the gate GE mentions in their literature that Five-Star Brand is not a “Selected” brand, but tubes that have been specifically designed for high-reliability – take that Genalex 🙂
The brand has been created in response to requirements from airlines that made conventional tubes unsuitable for aeronautical applications. Later on, military JAN specifications were incorporated into the program. The brand itself was launched in 1951 – the earliest high-reliability tube brand as far as I know.
Some of the major improvements in Five-Star Brand include:
- Redesign for higher heater current with a heavier heater wire to reduce burn-out
- The second coating on all bends of a heater wire
- Use of gold-plated grids for reduced grid emission
- Redesign to withstand shock and vibrations: multiple supports added, clamps on vertical support tabs were welded in place to increas structural strength, etc.
- Fifty-hour aging on all tubes directly at the factory.
- Many improvements in quality control
- Each mica was doubled (2 micas on the top of each other)
- Triple-Mica was introduced, where applicable, to improve initial leakage characteristics – by keeping conductive deposits of the getter material of the top mica with electrodes.
- In applications where vibrations were an issue, a shorter plate was introduced (12ax7 -> GL-5751)
Great list, which some similarities with Sylvania Gold Brand, but it looks like they didn’t go as deep as Sylvania. However, based on my experience, Five-Star brand has some incredibly good sounding tube GL-5751 Black Plates, GL-6386, GL-6072, etc.
A list of tubes in Five-Star family (not complete). All Five-Star tubes start with GL-: