In the maker movement, the ability to solder is one of the great dividing lines – rather like compiling your own kernel in Linux programming. Just as a programmer who has not compiled a kernel is often limited, unless you know how to solder, the work you can do is limited, as well as the do-it-yourself (DIY) kits you can assemble. To help bridge this divide, Audio Builders Workshop (ABW) [1] has developed two kits to teach soldering basics: a metronome that emits a regular number of beats per minute to mark the musical frequency of sound, and a low pass filter that controls sound levels. Armed with these kits, ABW has held soldering workshops around Boston. In the last year or so, it has also started making the kit available to other interested groups and holding workshops from Anaheim to Frankfurt.

ABW is a special interest group of musicians, educators, and tinkerers in the Boston chapter of the Audio Engineering Society (AES), sponsored by Analog Devices, Inc. and Mouser Electronics. ABW was founded by Owen Curtain, who explains, "I held the first Audio Builders Workshop as a way to learn more about product development. When 50 people showed, I decided to continue with more events. Within a year, we had held lectures on operational amps, a Compressor Hackathon, and a DSP lecture series. With small groups, we also built microphones, DI boxes, and microphone preamps." This work is carried on by a small group of regulars plus volunteers recruited for specific events.

Brewster LaMacchia, a core ABW participant, notes that the group has "been focused on DIY rather than specific open source thinking. While the source of the hardware is there, I don't think there's an open hardware license on most of the commercial DIY company offerings." However, for all practical purposes and by any definition, the kits can be described as open hardware even without the formality of a license. Moreover, the build instructions are released under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

According to LaMacchia, the kits arose out of the realization when holding workshops (Figure 1) that "many people were interested but had never soldered before and were hesitant to spend a few hundred dollars on something that looked overwhelming to someone who's never touched a soldering iron. We thought a low cost kit would be a good way to get started, but most of those are cheap kits with very limited build information. So the idea became 'let's offer a low cost kit with extensive build documentation and hold group learn-to-solder events to introduce people to building their own audio gear'."

Figure 1: One of ABW's soldering workshops held in the Boston area.

Chris Kinkaid, another ABW regular, adds, "We've seen how excited first-time DIYers get about building audio gear. This year ABW has been invited to speak and workshop at half a dozen different events, but it's been tough because this is a labor of love and we all have day jobs as engineers and teachers. But we are currently navigating how we can take on more of these events and grow the mission of ABW. As educators and engineers, we know how empowering it is to understand how the tools we use every day work, and we want to help others in that discovery."

The Kits

Both of ABW's current kits (Figure 2) are musically oriented, because many AES members are either musicians or involved in music production. "They're probably more fun than blinky-light ones," LaMacchia adds, referring to similar kits on the market. He goes on to explain that the metronome is built using 555-based circuits (one with three 5K Ohm resistors), a common choice for hundreds of beginner projects. The metronome includes a line-out jack, so it can be used with other equipment, while the low pass filter can be built into a guitar pedal. Neither kit includes a case, although one could easily be made with a 3D printer or by following the build instructions and modifying a standard plastic case.

Figure 2: The two kits laid out: the metronome (left) and the low pass filter (right).

Besides the kits, users will need a 9V battery, and a soldering kit that includes a soldering iron, solder, wire strippers, needle nose pliers, and wire cutters. The build instructions also suggest that users read some preliminary online instructions on the basics of soldering, such as MightyOhm's solder comic [2]. The kits are designed for users to gain experience soldering, rather than to teach them from the very beginning. However, such preliminaries would presumably be covered in a workshop, and the build instructions include useful items such as basic safety precautions. Slightly more advanced topics, such as reading resistor color codes and how to orient capacitors and diodes, are given in the build instructions [3]. To further simplify the process, the kits' circuit boards are labeled to reduce the chance of error.

The build instructions are similar to the highest level of verbosity in some command-line tools: likely to be annoying to experts, but full of valuable information for those who need it. No assumption of previous expertise is made, so the result is a primer on basic electronic concepts. The primer is enhanced by high-resolution images of resistors and other hardware and sharp close-up images of routine tasks like bending leads with needle nose pliers.

After this basic information, the build instructions get down to assembly, starting with an overview, and giving hints that can help orient users as they work. The instructions close with detailed troubleshooting suggestions. The result is some of the best technical documentation I have seen in 25 years of writing instructions. Moreover, in the unlikely event that a solo user needs more help, they can access the notes for workshop leaders [4] or ask for help on Facebook [5].

LaMacchia estimates that an expert could assemble one of the kits in 20 minutes, largely because of the labels on the PCBs. However, he adds, "we find that most people who have never touched a soldering iron leave with a working metronome in 1.5 to 2 hours. The low pass filter takes slightly longer."

More importantly, of course, those who complete a kit (Figure 3) leave with soldering experience. "In terms of feedback," LaMacchia says, "it's been absolutely fantastic. We have had so many people walk in with a 'I'm not sure I can do this' outlook and when they hear that tick-tick-tick of the metronome are literally jumping up and down saying, 'I made this and it works!' Particularly in the groups, there's a lot of high-fiving and selfies with working hardware going on. As an instructor at these events, it's really rewarding."

Figure 3: The two assembled kits mounted on a plastic board. The metronome is on the left.

Future Plans

Having created the kits and workshops, ABW is starting to distribute both more widely. "We now have a group of volunteers in New York City that are working to replicate what we've done here in Boston," LaMacchia says."They held one even this fall and more are in the works. We're also reaching out to other AES sections, as well as educators." One especially successful off-shoot is Pathfinders Outdoors, run by Buddy Lee Dobberteen, which runs build workshops for veterans with PTSD [6].

In addition, after a token crowdfunding campaign, the kits are now being sold on Crowd Supply [7], a crowdfunding site that specializes in open hardware.

In 2019, ABW has spent most of its time developing the kits. In the near future, it hopes to return to a breadboard kit it developed in 2018. The idea is to have a kit full of audio parts that people could use as they see fit – "something like the old Radio Shack 100-in-1 kit, brought in to the open source/sharing age," says LaMacchia. "We hope to get back to that project, as well as some other ideas that we have for related low-cost ways to introduce people to DIY audio electronics. In the longer term, we want to have some offerings for digital signaling processing. That topic is more complex, but we've had a lot of interest from the AES members about some software equivalent to the 'learn to solder concept' – that is, a way to ease people with no background in to it."

Perhaps ABW could consider the option of shipping its kits with soldering kits and cases to offer more complete experiences to users – and to spare them the annoyance of having to wait while they order additional supplies. However, so far as the goal of teaching soldering, ABW succeeds outstandingly, providing a detailed, hands on experience with concrete results. It's the sort of knowledge that both makers and supporters of open hardware need for their movements to succeed.