Yellow Jacket Tube ConvertersYellow Jacket® tube converters allow EL84 power tubes to be used in place of the most common guitar amp power tubes, including 6L6, EL34, 6V6, 7027, 6550, and 7591. Most Yellow Jacket® converters provide a substantial output power reduction and a "self-bias" Class A configuration for the EL84 so that no bias adjustment is required. Yellow Jacket® converters are like getting a whole new amp.
Tube Converter - Yellow Jacket® YJ20, for low-power amps
The YJ20 is for use in most amplifiers using 6V6 output tubes. The YJ20 is similar to the YJC but does not drop the plate and screen voltages. It is meant for use in lower power output amps (20 watts or less) when no power reduction is desired.