General Electric JAN metal base 6550A matched pair, 1985
The GE 6550A metal base is heavy a powertetrode produced for the Joint Army Navy. Popular in guitar and audio amplifiers as a heavy duty power tube respectively. One of the few American 6550A's still available.
GE (General Electric)
Founded by Thomas Edison, the inventor of light bulb, in 1892, General Electric or GE for short has become one of the largest corporations in the world.
Important steps towards the improvement of the electron tube by GE are a better diffusion pump to create a better vacuum in the tube and a process to prolong the life of the tungsten filament (tungsten wire or filament in English).
In the 1950s, GE started a project to improve the lifespan and reliability of their tubes and this resulted in the so-called 'Five Star Series'. The best-known signal tube in that series is the GL-5751 a tube with a 30% lower gain than the 12AX7
In 1945, GE took over the famous tube brand Ken-Rad (Kentucky Radio Corporation) and continued to produce tubes in Kentucky under that name until 1952
TubeDirect strives to offer both GE and Ken-Rad NOS tubes in its product range. This NOS (New Old Stock, not second-hand) tubes are used by reliable suppliers from the USA and tested for delivery by us and provided with an individual test report. Multiple tubes of the same type are matched as much as possible. See also our articles about testing and matching tubes.
This set of tubes is matched. This means that the measured values of the tubes fall within the same range and thus perform equally.
This is important for two reasons:
1. To obtain the same gain factor per tube.
2. For the same amount of quiescent current per tube.
The first requirement speaks for itself and the second requirement prevents the one tube where a higher quiescent current or bias is needed to make it work in the linear region will also be worn out earlier. Both new tubes and our NOS tubes can be ordered separately.