amp build 2- the Dirty Cow
Another 386-based lo-fi bass amp build, again inspired by ideas from Beavis Audio Research and Runoffgroove. This one is a bit more complicated, incorporating power supply filtering (via 220uF capacitor), buffered input (via 2N5951 transistor), and a tone control (from the Beavis Audio article on the Big Muff Pi tone stack, inserted between volume control and 386 input pin).
The input section (including buffer) is like the one from the Beavis Audio Noisy Cricket design, but with the BMP tone stack instead of the one from the Cricket. Also, I used a single 100nF cap in place of the 47nF specified in the Cricket schematic, and omitted the second input cap. The rest of the design is inspired very much by the Grace Overdrive design from Runoffgroove, with a larger output cap.
Perhaps you’re wondering where the name came from… well, like the Candy Land Combo, the Dirty Cow gets its name from its enclosure:
The jack with the red plug in it is the input, output is on the back. There is a power switch and LED, and the knobs (from left) are: gain, tone, and volume. Their placement is a bit misleading, since I went with a “non-master” volume setup (the volume is on the input, not the output). That also means the volume and gain knobs are interactive, allowing for a more adjustable response. Compared to the Candy Land amp, this one is a little louder, but is also capable of more sounds approaching “clean” territory. Here’s some audio (kinda sloppy playing, sorry)- first up, a cleanish tone (same active Ibanez bass as last time) volume just over 3/4, gain lowish):
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and here’s a more distorted one (volume and gain around 3/4):
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…and some even sloppier guitar playing, gain and volume cranked (passive-pickup cheap Strat copy):
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