Old tube radios are sometimes converted into amps for a few purposes: one being to make guitar amplifiers, and another as a makeshift public address system. Many vintage radios already have most of the correct parts to be converted into a tube amp. The easiest approach is to find one that already had a phono jack as an auxiliary output in place. Look for radios that have a good audio output section with two transformers (one for power and the other for sound) or 6V6 tube(s).
Instructions
Connecting an Audio input Jack to a Tube Radio
1. Mount a 1/4-inch phono jack to radio at a convenient location, like through the radio chassis or the radio's housing of wood or plastic. Screws and nuts are used for chassis, while a longer threaded jack with a hexagonal nut is used for wood or plastic.
2. Solder the insulated stripped wire to the mounted jack center post. Note: Wood or plastic mounted jacks require a connection from outer part of jack to the chassis.
3. Remove the center wire on the radio's volume control. Tape it and leave it in place for possible reconnection later if the radio portion is to be used.
4. Solder the stripped end of the insulated wire from the jack center post to the center post of the volume control.
5. Plug in your auxiliary audio source (i.e., mike or guitar) and adjust the volume control.
Tags: center post, volume control, converted into, jack center, jack center post, phono jack