THD YELLOW JACKET® YJ7591 CONVERTERS

• Converts most audio amplifiers with 7591 and similar-based tubes to EL84/6BQ5 tubes without modification or rebiasing.

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

• Slight power reduction from 7591.

• Safe for all common amplifiers and transformers.

• EL84/6BQ5 tube not included but available from Radio Daze.

INSTALLATION
1.  With your amplifier cold and turned off, remove the 7591tubes 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, 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.  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.

If you are not sure if the YJ7591 Yellow Jacket will work in your application, 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's Brown Deluxe Amp (6G3), Princeton, Tremolux (5G9, 6G9) and Vibrolux (5F11, 6G11) to name a few.

If your amp uses 6V6 output tubes, you need the YJ20 Yellow Jacket.  If your amp uses 6L6, 6550 or EL34 family tubes, you should use the YJS Yellow Jacket.  The correct unit can be obtained from Radio Daze.  If you need to exchange it, please contact the THD factory.