Tube Converter - Yellow Jacket® YJS, for fixed-biased tubes

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Tube Converter - Yellow Jacket® YJS, for fixed-biased tubes

$29.95
In Stock

The YJS 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 YJS is for amps with fixed bias power tubes. (Fixed bias tubes have their cathode connected directly to ground and a negative DC voltage applied to their control grid). See P-SAYJ-C for cathode-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%. The triode version provides a greater power reduction and more linearity than the standard (pentode) version.
  • 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, plug the EL84s into the Yellow Jacket® converters, turn on the amp and play.

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

Part Numbers
TypeOur Part NumberUPC/EAN
Standard (Pentode)P-SAYJ
Reduced Power (Triode)P-SAYJ-TRIODE841358108457
Product Measurements by Type
Item Diameter1.301 in.
Item Height, without pins2.18 in.
Item Height, with tube5.0 in.
Packaging Information
Packaging Dimensions3.75 in. × 1.25 in. × 1.25 in.
Weight (Packaging)0.111 lbs.
Product Measurements by Item
P-SAYJ - Standard (Pentode) versionItem Diameter1.301 in.
Item Height, without pins2.18 in.
Item Height, with tube5.0 in.
P-SAYJ-TRIODE - Reduced Power (Triode) versionItem Diameter1.301 in.
Item Height, without pins2.18 in.
Item Height, with tube5.0 in.

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Product Reviews

5.00 out of 5 based on 2 reviews
whitbysound - April 25th, 2022
5 out of 5

Have 4 YJS for a Marshall 210H. Can be used as quad, duplex or in concert with the original tubes. Switch out matched quads of J/J, Sovtek, TAD and Mullard EL84s. Along with the original Marshall tubes and some TADs, a total sound machine. Side bar: also purchased TAD Tone Bones, DO NOT purchase Tone Bones which cause massive cavitation noise. Stick to the Yellow Jackets, can't go wrong or run out of options.

Steve F. - March 7th, 2022
5 out of 5

Tonal game changer for me! The Yellow Jacket YJS allowed me to achieve the natural overdrive tone I was seeking in my JCM 800 and my 59 Bassman Reissue without having to crank the amps to an ear splitting volume. I have tried power soaks and pedals but nothing compares to the simplicity of using the Yellow Jacket YJS.

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