This model of Yellow Jackets® converter, the YJ7591, is a specialized, current-limiting/voltage-conditioning adapter for use in most amplifiers which use 7591 output tubes. All Yellow Jackets® converters come with JJ Brand EL84/6BQ5 vacuum tubes. Converts most audio amplifiers with 7591s to EL84s without modification or rebiasing. Converts: Class AB to Class A operation Drops Output Power: Slightly. Safe for all common amplifiers and transformers. Yellow Jackets® converters are a type of specialized adapter which permit the use of EL84/6BQ5 power tubes in place of 6V6, 6L6, EL34, and 7591 type vacuum tubes. Yellow Jackets® converters allow you to harness the musicality of EL84 vacuum tubes in amps that don't use them already - it's like getting a whole new amplifier! In place of a 6V6 a Yellow Jackets® converter will even out the tone and make it sound stronger. In larger amps that use two 6L6, 6550, 7027 or EL34 power tubes the Yellow Jackets® converter will drop the output power to about 15 to 20 watts, giving it more of a vintage VOX AC30 sound. In amps that take four power tubes the Yellow Jackets® converter will sweeten the tone and make it more dynamic. There is no rebiasing involved, which makes modifying your amp's tone very easy. More...

This model of Yellow Jackets® converter, the YJ20, is a specialized, current-limiting/voltage-conditioning adapter for use in most amplifiers which use 6V6 output tubes, or other similar-based tubes, such as the 6F6, 6G6, 6K6, 6Y6, etc. All Yellow Jackets® converters come with JJ Brand EL84/6BQ5 vacuum tubes. Converts most audio amplifiers with 6V6s and similar-based tubes to EL84s without modification or rebiasing. Converts: Class AB to Class A operation Drops Output Power: Does not drop power. Safe for all common amplifiers and transformers. Yellow Jackets® converters are a type of specialized adapter which permit the use of EL84/6BQ5 power tubes in place of 6V6, 6L6, EL34, and 7591 type vacuum tubes. Yellow Jackets® converters allow you to harness the musicality of EL84 vacuum tubes in amps that don't use them already - it's like getting a whole new amplifier! In place of a 6V6 a Yellow Jackets® converter will even out the tone and make it sound stronger. In larger amps that use two 6L6, 6550, 7027 or EL34 power tubes the Yellow Jackets® converter will drop the output power to about 15 to 20 watts, giving it more of a vintage VOX AC30 sound. In amps that take four power tubes the Yellow Jackets® converter will sweeten the tone and make it more dynamic. There is no rebiasing involved, which makes modifying your amp's tone very easy. More...

This model of Yellow Jackets® converter, the YJR, is an adapter for use in most amplifiers which use 5AR4, 5U4, or 5Y3 tubes or other similar tubes. This Yellow Jacket® is a solid state device and as such does not come with vacuum tubes. Converts most audio amplifiers which use a vacuum tube rectifier 5AR4, 5U4 or 5Y3 to a solid state device. Safe for all common amplifiers and transformers. All Yellow Jackets® have a two year warranty against manufactured defects.