Last week was busy in the shop.
This is a 2-watt per-channel stereo power amp built for our friends K&D. It is tiny (only 10 inches wide). The form of the amplifier was driven by the styling of these beautiful black-lucite vintage speakers which complete the set.
The speakers were made by Speak-Easy Intercom of Kansas City, likely in the early 50′s. They are handmade from individual pieces of black lucite. I found them with the original base-station for the intercom, all in flawless condition. I replaced the drivers in the speaker cabinets. This tiny tube-audio system is intended as a casual background-music-listening setup for the home or office.
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A couple more ‘Recycled’ Tweed Champ Clones were born last week as well. These are headed for sale at Main Drag Music in Brooklyn.
I have decided on the name ‘Cassius’ for these and all future small single-ended 5watt guitar amps. ‘Cassius’ being the name of the most famous Champ of the 20th century.
I built these with identical circuits, very true to the circa 1955 5E1 schematic. They use a 6V6 output tube with a 12AX7 preamp tube. They have choke transformers and a feedback circuit. The output transformer is mounted directly on the 8″ Alnico speaker in order to conserve space. I used a 6X5 rectifier tube rather than a 5Y3 so that i could use a slightly smaller-sized power transformer. The 6X5 is an excellent tube which was used in a great amount of pro-audio equipment in the 50s. These amps also will also accept 12AY7 preamp tubes for a different breakup.
These amps are very small and lightweight. They sound fantastic. Extremely dynamic. The range of sound that you can generate using the volume knob on the guitar is outstanding. The small Alnico speaker magnet make these amps less efficient than some other 5 watt amps, which makes these ideal for apartment dwellers (or anyone who lives with other people!).
Up next: this week I will be building a similar ‘recycled’ guitar amp, but scaled up: a 12-watt “Tweed Deluxe-type” amplifier with a 12″ field coil speaker.