The Yellow Jacket YJS Power Tube Conver allows you to convert amplifiers that use Octal tube sockets (EL34, 6L6, 6440, 6V6) to use EL-84s instead, allowing you to lower the output wattage/volume, and explore new tonal characters.
The YJSD is a Duet of their YJShort - Standard Duet Class-A Tube Convertors, and includes a set of matched EL84 tubes.
The YJShort is shorter than the standard YJS converter, allowing for use in amps that do not have room for the standard converters. It is a specialized, current-limiting/voltage-conditioning adapter for use in most 20 to 100 watt amps which use 6L6, EL34, 6550 or 6V6 output tubes. All Yellow Jackets converters come with JJ Brand EL84/6BQ5 vacuum tubes.
Yellow Jackets are specialized adapters which permit the use of EL84/6BQ5 power tubes in place of 6V6, 6L6, EL34, 7027, 6550 (under 520 volts), and 7591 types. They will work in any amplifier that takes these tube types, as long as the plate voltage is under 520 VDC. This accounts for over 98% of the tube guitar amplifiers on market. (They also work in tube Hi-Fi equipment!) Because the Yellow Jackets ignore the amplifier’s grid bias voltage, it is possible to take them in an out at will to adjust your power level and sound for the individual gig or session.
Class-A With Any Amp!
Yellow Jacket Converters not only rearrange the pin locations of the 9-pin EL84 tube bases to permit them to work in 8-pin sockets, but also perform a number of essential electronic functions that permit the EL84s to function well and sound great in your amplifier. These functions include: 1) Reducing the voltage on the plates of the tubes, 2) Reducing the voltage and limiting the current on the screens of the tubes, 3) Blocking the amplifi er’s DC bias voltage from reaching the control grids of the EL84s, 4) Giving the control grids of the EL84s their own ground reference resistor for gain control, 5) Giving the EL84 its own cathode-bias (selfbias) circuit to enable it to run safely and squarely in the Class-A range.
Like Getting a Whole New Amplifier!
In Champ and Deluxe type amplifi ers, the Yellow Jackets output is smooth, strong and more even than with the stock 6V6s. When the Yellow Jacket Converters are installed in larger two-tube amplifi ers intended for 6L6, 6550, 7027, or EL34 output tubes, the output power drops to about 15 to 20 watts and the amplifi er 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 than stock 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 YJSs can be used. If only two are used and the other two (inside or outside) sockets are left empty, 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. A further option in a 4-tube amplifi er is to leave two of the original tubes in place and replace the other two with Yellow Jackets. This gives a combination of Class-A and Class-AB operation and sounds quite sweet and complex. The pick attack si tight and punchy from the power of the two Class-AB tubes and the sustain is taken over by the Yellow Jackets operating in Class-A. Try it, you’ll like it!
Replaces the Rare 7591 Tube!
In the case of replacing 7591s, the overall output power remains the same, but the sound becomes fuller, and the extinct 7591s 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 rare 7591 tubes. Safe for All Amplifier and Transformers As all Yellow Jacket Converters internally limit voltage and current, they put no extra strain on the amplifier’s 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, 6550, 7027, EL34 or 7591, so using the Yellow Jackets will reduce the strain on the filament windings of the power transformer as well.
Safe for All Amplifier and Transformers
As all Yellow Jacket Converters internally limit voltage and current, they put no extra strain on the amplifier’s 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, 6550, 7027, EL34 or 7591, so using the Yellow Jackets will reduce the strain on the filament windings of the power transformer as well.
Features:
• YJShort Standard Version Drops Output Power 50% to 70%
• Converts most audio amplifiers with 6L6s, EL34s, 6550s or 6V6s to EL84s without modification or rebiasing.
• One year warranty for manufacturer defects
• Safe for all common amplifiers and transformers
• Short enough to fit in most Blackface Fender heads
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