Tube Converter - Yellow Jacket® YJC, for cathode-biased tubes

Tube Converter - Yellow Jacket® YJC, for cathode-biased tubes

Yellow Jacket
Tube Converter - Yellow Jacket® YJC, for cathode-biased tubes image 1
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The YJC is a specialized, current-limiting/voltage-conditioning adapter for use in most 20 to 100 watt amps that use 6L6, EL34, 6550 or 6V6 output tubes. The YJC is for use in amps with cathode-biased power tubes. Cathode-biased power tubes have a bias resistor connected from their cathode to ground. The ground wire of the YJC is used to bypass the amp’s cathode bias components so the Yellow Jacket® converter’s internal bias components are used instead. See P-SAYJ for fixed-biased tubes.

  • Converts most audio amplifiers with 6L6s, EL34s, 6550s, or 6V6s and similar-based tubes to EL84s without modification or rebiasing.
  • Converts: Class AB to Class A operation
  • Drops Output Power: 50% to 70%.
  • Safe for all common amplifiers and transformers.

Converter-only. Tubes not included. Requires an EL84 vacuum tube (see accessories below for options).


Yellow Jacket® 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 Jacket® 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!

There is no rebiasing involved, which makes modifying your amp's tone very easy. Yellow Jacket® converters give you simple Class-A operation from any amp. They not only rearrange the pin locations of the tubes, but also provide the necessary plate voltage drop and current limiting on the screens as well as blocking the amplifier's grid bias voltage while configuring the EL84 in a Class-A, self-adjusting cathode-bias circuit. In other words, there are no adjustments to make and no modifications necessary, you simply plug the Yellow Jacket® into the amp's output tube sockets, (in cathode-bias amplifiers) screw the ground wires under one of the output tube socket mounting screws, plug the provided EL84s into the Yellow Jacket® converters, turn on the amp and play.

All Yellow Jacket® converters have a one year warranty against manufactured defects.

Product Measurements by Type
Item Diameter1.301 in.
Item Height, without pins2.18 in.
Item Height, with tube5.0 in.
Packaging Information
Packaging Dimensions4.75 in. × 2.25 in. × 1.33 in.
Weight (Packaging)0.111 lbs.

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