THD YELLOW JACKET® YJC CONVERTERS

• Converts most audio amplifiers with 6L6, EL34, 6550 or 6V6 tubes to  EL84/6BQ5 tubes without modification or rebiasing.

• Converts from Class-AB to Class-A operation.

• Drops output power by 50% to 70%.

• Safe for all common amplifiers and transformers.

• Connects to chassis-ground for cathode biased amps.

• EL84/6BQ5 tube not included but is available separately.

INSTALLATION
1.  With your amplifier cold and turned off, remove the 6V6, 6L6, EL34 or 6550 tubes from their sockets. (Use a towel to protect your hands if the tubes are hot.)

2)  Place the Yellow Jacket Converter in the tube sockets. If your amplifier is cathode-biased, screw the ground wire under the tube socket mounting screw (to provide an adequate ground connection), and install an EL84 tube into the Yellow Jacket.  If it is grid-biased, you can ignore the ground wires.  Make sure that all pins are properly aligned and do not force anything.  It should all go smoothly if the tubes are properly aligned.

3)  Turn the amp on, let it warm up, and play. Your amp is now running in Class-A mode with and EL84 output tube.

You do not have to adjust the bias of your amplifier as the Yellow Jackets themselves create their own cathode bias circuit, ignoring the bias settings in your amp.  This also means that when you put your old tubes back into your amplifier, your bias will be set just as you left it.

Yellow Jackets are NOT to be used in amplifiers with extremely high plate voltages such as Marshall Majors, Ampeg SVT's, Hi-Watt 200's and Orange 120's.  These amplifiers have too high a plate voltage and will damage the EL84's and possibly the Yellow Jackets themselves.

If you are not sure if the YJC Yellow Jacket will work in your amp, please feel free to contact THD at the factory either by phone or e-mail.  They will be happy to advise you on your individual situation.

Amplifiers which vary the bias voltage to create tremelo effect will not have any tremolo effect when using the Yellow Jackets.  This includes the Fender Vibro-Champ,  Brown Deluxe Amp (6G3), Princeton, Tremolux (5G9, 6G9) and Vibrolux (5F11, 6G11) to name a few.

For 6V6 amps where you do not want to drop the power of the amplifiers (other than Jim Kelley Amps which require the voltage reduction circuitry), the YJ20 can be ordered.

If your amp uses 7591 output tubes, you need the YJ7591 Yellow Jacket. The correct unit can be obtained from Radio Daze.  If you need to exchange it, please contact the THD factory.