Older tubes from Telefunken and Amperex used to flash metal directly onto the base of the tube between pins 2 and 7. I can only assume this was to reduce the number of physical leads inside the bottle. The JJ EF806-S is a very good replica of a Telefunken and uses this method today. Here is a quote from an old Amperex data sheet for the EF86: JJ EF806 is a pretty good tube, the only thing missing is EF86 marking because it is not near specifications of real EF806. Requires sorting to get low noise and tight bias as ral tube of this type should have. Microphonics are not an issue in combo amps, so we finally have an EF86 type that works at this conditions.

Adding an EF86 to any tube amplifier. The EF86 pentode. Vox used'em, and so did Matchless and Dr.Z. They are cool tubes, and they have a different personality than the more common 12AX7 preamp stage. The problem with having an itch for a EF86 is that, in most cases, a EF86 based amplifier is well over $1000. Watford Valves, one of Europe's leading suppliers of tested, graded and guaranteed valves to the professional music industry. We offer some of the most comprehensive testing facilities available today. Feb 27, 2012 · Here's my latest build - an extremely simple single ended circuit with an EF86 preamp and Hall Amplification's VVR for voltage/power scaling. It can be run with either an EL34 for 8 watts, or a ...