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.
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.
Like the previous Recycled Champs, these are freshly-built guitar amplifiers, built with largely new components, into antique cabinets. In this case, factory/school PA speaker boxes.
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.
7 replies on “some recent pieces”
those are some handsome, handsome beasts
Great job. I’m in the process of building a Champ right now. Could you post or send some pictures of the circuit board? That’s my concern right now – and I’d like to have something to model after.
Thanks – Jerry
hi jerry. i actually don’t have photos of the circuits (there are no circuit boards, btw – it’s all point-to-point wiring with a few terminal strips thrown in), and all of these have sold, so i can’t photo them for you. You can google ‘fender champ layout’ to see how leo did it – this is a good place to start -but don’t get too hung up on copying his layout exactly. just remember these basic tips: *keep all leads as short as possible. *put the input stage as far away from the power transformer as you can. *keep the heater wires twisted and away from the audio path. Now, i also recommend using a 10gauge copper ground ‘buss’ wire which only attached to the chassis at the input jack, but Leo did not do this and his amps all sound great so….
It’s silly to use a tube rectifier in a Class A single ended amp. They don’t modulate the power supply, so there is no sonic effect.
You can use two common flat pack 6/12-120/240 four winding transformers instead of a purpose built power transformer by wiring them back to back, if you don’t need a 5 volt rectifier winding. Gateway in St. Louis has these for about a buck and a half apiece.
Hi Gary. Care to send me a link? I can’t find such an item on their website. c.
Do you sell just the internals? I already have the box.
Just came across your page after a web search for 6V6 amps. I, too am of the (very strong) opinion that the absolute best-ever sounding audio amp is one with a 12AX7 preamp, and 6V6 output. END OF STORY!!!