This section contains detailed technical information and pretty much everything you need to know about the miniature B9A tubes (12AX7, 12AU7 and 12AT7 types) utilised in the larger Effectrode effects pedals and in the Binson Echorec tube echo-delay machines and the subminiature types used in our smaller pedals. It also contains fascinating historical articles about these marvellous devices and vacuum tubes in general.
The detailed drawing below, taken from the 1950 edition of the RCA Receiving Tube Manual, clearly shows the internal construction of a miniature signal tube.