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THD Yellow Jacket Converters w/EL84 Duet Tubes Single

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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 types.How do they work?They give you simple Class-A operat... Click To Read More About This Product

Available 01-09-2018 You will not be charged until order ships. Email me when this is in stock.

Gear returned in mint condition. If you're looking for a virtually new instrument in possibly less-than-perfect packaging, this is a great value.
  • Includes 45-Day, No-Hassle Returns
  • Includes full manufacturer's warranty
Gear returned in great condition, with only minor signs of use, such as slight scuffs or pick marks. It looks and plays like new and may be considered an equivalent to display units found in retail stores.
  • Includes 45-Day, No-Hassle Returns
  • Includes full manufacturer's warranty
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Ship to Store Available in: 3-7 Days (estimated) Fairfax, VA (15.38  mi) View More Stores For Availability Store Information


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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 types.

How do they work?
They give you simple Class-A operation from any amp.Yellow Jacket Converters not only rearrange the pin locations of the tubes, but also provide the necessary current limiting on the screens and cathode as well as blocking the amplifier's grid bias voltage, while configuring the EL84 in a Class-A, Self-adjusiting cathode-bias circuit. In other words, there are no adjustments to make and no modifications necesary, you simply plug the Yellow Jackets 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 EL84's into the Yellow Jackets, turn on the amp and play.

How will they change my amplifier?
It's like getting a whole new amplifier! In Champ and Deluxe type amplifiers, the Yellow Jackets output is smooth, strong and more even than with the stock 6V6s. When the Yellow jackets Converters are installed inlarger amplifiers intended for 6L6s or EL34 output tubes, the high plate and screen voltages are reduced as well as current limited to protect the EL84 and to drop output power. When a pair of Yellow Jackets are used in a Marshall 50 watt or similar amplifier, the overall power drops to about 20 watts and takes on more of the character of an old Vox AC30. The distortion is smoother and more even and the output is both substantially reduced and more compressed due to the Class-A nature of the Yellow Jackets. In a 100 watt amp like a Twin Reverb or Marshall 100, either two or four Yellow Jackets can be used. If only two are used and the other two sockets are left empy, the output is dropped to about 20 watts. With four in place, the amp puts out about 40 watts and takes on a whole new warmth and richness.

In the cases of the YJ7591 converters, the overall ouput power remains the same, but the sound becomes fuller and the extinct 7591 are replaced with common and inexpensive EL84 tubes. In old Ampeg Reverb Rockets and the like, you experience a warmth and sweetness that you could never get with the now unavailable 7591 tubes.

Will they hurt my amp?
No! Yellow Jacket converters are safe for all amplifiers and transformers. As all Yellow Jacket Converters internally limit voltage and current they put no extra strain on amplifiers' power and output transformers or internal components. Using the Yellow Jackets in higher powered amplifiers actually reduces the strain on the transformers and internal components because it reduces the overall wattage of the system. Furthermore, the heater (or filament) current of the EL84 is lower than that of the 6L6, EL34 or 7591, so the Yellow Jacket will reduce the strain on the filament windings of the power transformer as well.


  • Can be used in place of 6V6, 6L6, EL34, 7027 6550 (under 520 volts) and 7591 types
  • Work in any amplifier that takes these tube types, as long as the plate voltage is under 520 VDC
  • Revitalizes the sound of your amp
  • Also work in tube Hi-Fi equipment
  • Customer Reviews

Review Snapshot

by PowerReviews
THDYellow Jacket Converters w/EL84 Duet Tubes

(based on 1 review)

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Reviewed by 1 customer

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(11 of 12 customers found this review helpful)


Sweet sound, much more managable volume.

By Aaron

from Napoleon, OH

Comments about THD Yellow Jacket Converters w/EL84 Duet Tubes:

I installed two of these in a Randall MTS RM100 reducing the overall power from 100 watts down to about 20. It was incredibly easy, simply plug and play. They do not even require a re-bias. From the time I opened the package, I was playing within 10 minutes. These made my volume much more manageable. For me, the RM100 was really overkill, but I love everything about it. It sounds and looks killer. The only downside of the amp for me was that the volume was very difficult to manage in the confines of my small playing space. With the Yellow Jackets, it is still loud enough to decimate my neighborhood, knocking children off skateboards and making decent folks run for their lives. The master volume is much less sensitive and affords me the opportunity to dial in exactly the volume I need. I am playing a lot more through my RM100 thanks to these tubes. In closing I will list the pros and cons of these tubes (for those who�ۡ���ve skipped the narrative). Pros: 1) They sound incredible. 2) Very easy to install 3) More manageable volume, but leaves plenty of headroom. 4) Owns noobs and heals the sick. Cons: 1) A tad pricy. 2) I should have bought them sooner. You really can�ۡ���t go wrong with these.

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