Turning A Broken Bass Into A Headless Bass

January 11, 2013 by Brian Benchoff 5 Comments

bass

A while back [Michael] inherited a broken bass guitar from a friend. The headstock for this bass was cracked right down the middle, and the friend attempted a repair with a bolt and a couple of washers. After trying to figure out what the addition of a bolt was trying to accomplish, [Michael] set to work repairing this bass and ended up doing a headless conversion.

A headless bass, just as the name implies, does away with the headstock and moves the tuners to the other side of the guitar – in [Michael]’s case, right below the bridge. After sawing off the broken headstock above the truss rod, [Michael] made a string retainer and bolted it on to the remainder of the neck.

The tuners had to be moved, of course, so [Michael] routed out a section of the body below the bridge. Four holes were drilled and the original tuners slipped right in. The result is a perfectly functional bass that would fit right in to the tour van of an 80’s metal band.

You can check out [Michael]’s bass down in the pocket.

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A Really, Really Tiny Tube Amp

January 11, 2013 by Brian Benchoff 37 Comments

After building his first tube amp from a kit, he set to work on his next amp build. Since tube amps are a much more experimental endeavor than their solid state brethren, [Jarek] decided to make his next amp unique with military surplus subminiature tubes, and in the process created the smallest tube amp we’ve ever seen.

Instead of bulky 12AX7s and EL34s tubes usually found in tube amp build, [Jarek] stumbled upon the subminiature dual triode 6021 tube, originally designed for ballistic missiles, military avionics, and most likely some equipment still classified to this day. These tubes not only reduced the size of the circuit; compared to larger amps, this tiny amplifier sips power.

The 100+ Volts required to get the tubes working is provided by a switched mode power supply, again keeping the size of the final project down. The results are awesome, as heard in the video after the break. There’s still a little hum coming from the amp, but this really is a fabulous piece of work made even more awesome through the use of very tiny tubes.

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Letting [Euler] Help Out With PCB Fabrication

January 11, 2013 by Brian Benchoff 20 Comments

drillin

Since [Alessio] has been etching his own PCBs, he’s hit upon the most tedious part of the process, and the reason homebrew SMD boards are so awesome: drilling your own boards is a pain. While [Alessio]’s CNC mill takes care of most of the work, aligning the pre-drilled boards and correcting for any scaling issues from the mask is a bit difficult. With the help of a transform matrix, though, drilling PCBs has never been easier.

While the Gcode running the mill may be accurate, the actual manufactured PCBs might not be. If the extents on [Alessio]’s board aren’t exactly aligned with the axes of the CNC mill, the drill holes end up where they’re supposed to be. To solve this problem, [Alessio] wrote a PCB drilling transformational matrix calculator. The basic idea is by drilling just a few holes, [Alessio] is able to calculate any offset required in the Gcode with the help of a little bit of linear algebra.