PORTable Amplifier...
I’ll see myself out…
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Schematic
Based around an LM386 power amplifier IC, a speaker from an old surround system, and the box from a bottle of Grahams 20 year old.
Wirings pretty much taken directly from the datasheet, but with a toggle switch for on/off and the feedback resistor between pins 1 and 8 fiddled with for some more gain. I initially fiddled with the capacitor as well to correct the frequency response but I preferred the sound of the response when combined with the tube as it was.
Assembly
The bottom of the tube came off with some plier since it was originally crimped on. The lid was retained for use to replace the bottom whilst the speaker was to fill the top.
I built the circuit onto a bit of stripboard. Turned out quite neat to be fair.
The board was fastened to the inside of the tube using a glob of fixall.
The speaker had the flanges bent over with some pliers and some gentle persuasion. It as then mounted at the top of the tube facing upwards with pop-rivets using the original mounting holes. This gave for some quite considerable sound from the speaker, amplified massively by the tube.
The best solution for the 9V battery was to mount it using velcro to the inside. Since the bottom of the tube was removable this also gave enough room to stuff a spare guitar lead inside for safe keeping.
Sounds perfik.
Noice.