Photo Gallery Page 4
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Very Large and Very small
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This is my biggest amp to date, a 300 watt guitar amp with lots of bells and whistles. Here you see its humble beginnings as a bare chassis with layout paper stuck to it. 
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... and here you see the current status (as of May, 2002). This is a sneak preview of what the finished project will look like. All the power supplies and the PA are done and working well. Next step - preamps wiring. Click here or on the banner above to see the step-by-step evolution of this project. Click here for more pictures. |
Baby Bear
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'Way on the other end of the spectrum, here's "Baby Bear,", which might quite possibly be the World's Smallest Tube Guitar Amp. It's built around subminiature hearing-aid tubes, sporting a power output of a whopping 1.8 milliwatts. (That's right, "milli;" in other words, 0.0018 watts). 
It's entirely appropriate that it be housed in a Celestial Seasonings tea tin... notice the little tube radio that Sleepytime Bear is nodding off to? The 12AX7 is in the picture just to give an idea of the scale of this little project. Unfortunately, it still has "issues" as of this writing (May 2002) so it's not ready to be worked up into an article yet. Mainly, it doesn't have enough gain as an instrument amplifier, and its performance as a preamp are rather "restrained" also. 
However, in the interest of Mad Science, the schematic is published at the end of this page. It's basically the recommended mode of operation in hearing-aid service, one of the applications to which these little tubes were placed. ... and here it is with the cover open. Notice that the tiny tea-tin even includes the power supply! Filament voltage provided by an AA cell, and the zapping-high B+ of 24 volts is provided by a pair of 123A cells in series. Battery comparments and main "chassis" fashioned from perf-board. |
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Enough of this, take me to Fred's artsy side!