Audio Builders Workshop
Audio & Music

ABW Metronome & Low-pass Filter Kits

Two fun audio projects for learning to solder

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If you’re interested in learning how to solder for the first time or you want a fun new project to keep your soldering-skills sharp, these kits are for you! The ABW Metronome Kit and Low Pass Filter Kit were designed specifically with education in mind. Basic audio gear is a great vessel for hands-on solder education because you can see and hear the results.

Learn to Solder by Building Audio Gear

Audio Builders Workshop (ABW) is a program that works to provide educational opportunities for anyone to learn more about audio. To encourage musicians and audio engineers to build their own gear, ABW started to run build sessions for everything from microphones to guitar effects pedals. We quickly realized that while people were interested in building their own audio gear, many were intimidated by the cost and/or complexity of the projects.

That’s when we developed these low-cost, simple kits based on audio - to allow people to gain confidence to tackle commercial DIY audio kits. The kits work well for individuals as well as in group build environments.

Metronome and Low Pass Filter mounted on plexiglass for a demo.

If you’ve never soldered before, these kits are a great place to start

While a group build event with staff available to answer any questions you have is nice, we find that most people who read over the Solder Comic can start right in on building the kits without problems. There are also a large number of videos and other learn-to-solder guides that can be found with a quick query on the ‘net, search for soldering tutorial.

The Metronome Kit

This kit is the easier of the two and the one we suggest for group builds with people who have never soldered before. The final result produces a steady beat with a wide range of tempos. The kit offers three output methods:

The switch allows the speaker to be shut off, allowing use of the LED or line out for cases where the speaker noise would be problematic. The circuit is powered by a 9 V battery.

The PCB is a single-sided board, which means that if you make an assembly error, unsoldering components is easier than with the typical two-sided board.

An experienced person can build the kit in under 20 minutes. When we run group build sessions, most people finish in 90 minutes, with a few going to two hours.

Kit Contents

A 9 V battery is not included.

Certain tools are required for this kit.

Instructions can be downloaded from the project site.

We suggest that the kit be placed in a case to make it easier to use and to protect it from damage. A case is not included. Designing your own case is also a great way to personalize your metronome. The build directions show an example case from a stock plastic box purchased from a local art supply store chain.

The Low-pass Filter Kit

This kit includes all the components needed to create an analog audio effect capable of processing audio in real time. The analog audio effect in the spotlight is an adjustable resonant low-pass filter. Similar to what you hear from a synthesizer or a DJ, the filter adds texture to existing sound, instruments, music, microphones, and more. With a bit more experimental effort, this kit can be an avenue to explore other filter shapes or even a self-oscillating voice, producing its own audio to pull you into the crafty world of making electronic music.

The knob (potentiometer) controls the cutoff frequency of the filter. This controls the range of high frequencies allowed to pass to the output with a narrow boost at the end of this range.

Low-pass Filter Frequency simulation.

Power is applied via 9 V battery or DC wallwart. The audio input source and output to an amplifier (or other effects) are connected to the circuit via a 1/4" phone jack.

The PCB is a double sided board, which makes it slightly more challenging to unsolder components if you make an assembly error, but any errors wouldn’t be a show stopper. You’d just get some extra desoldering practice.

An experienced user can complete this kit within 30 minutes. When we run group build sessions, most people finish in 2 hours, with a few going on longer than 2 hours.

Kit Contents

A 9 V battery is not included.

Certain tools are required for this kit.

Instructions can also be downloaded from here.

We suggest that the kit be placed in a case to make it easier to use and to protect it from damage. A case is not included. Designing your own case is a great way to personalize your filter. A metal box will offer shielding, and the design can be used with a blank stomp-box type enclosure, though you may want to modify the wiring hookup to use a bypass switch.

Comparison to Other Kit Brands

555 based Yes NoYes
Line out Yes NoYes (needs external components for line level)
Speaker Yes NoYes
LED Yes NoNo
Reverse polarity protection Yes YesNo
Detailed assembly directions 27 pages of 'em NoReasonable
Planner for group builds Yes NoNo
All design files provided as source? Yes Schematic PDF onlySchematic PDF only
Backed by ABW? Yes Sure, we'll still help youDitto

This table compares the Metronome kit specifically. There aren’t a lot of Low-pass Filter kits out there, because it’s so simple.

What is Audio Builders Workshop?

ABW is part of the Boston section of the Audio Engineering Society, the global professional organization for people involved with all aspects of sound reproduction, either on a academic basis or as practitioners. ABW works to provide educational opportunities for anyone to learn more about audio. While nominally many of those activities take place in the Boston area, ABW volunteers are found worldwide and ABW has supported events in Boston, across the US, and most recently in Europe.

As a volunteer group, we were not able to easily provide kits to others outside of the workshops, so we turned to Crowd Supply to handle procuring the parts for the kits and all sales and distribution.

Previously someone wanting to do a group build would have had to deal with procuring their own parts and PCB blanks. Now, with Crowd Supply, you can simply place an order and the kits will be delivered to your doorstep. For group builds, we have created multi-kit packages to keep the cost as low as we can. Learn to solder with friends!

You can find out more about ABW on our website: You can also find the build directions and full details of the kits there as well. We also have a Facebook page for discussing DIY as well as answering questions about the kits. If you’re interested about some of ABW’s other activities, including a back catalog of talks and presentations, please check out our YouTube channel.

If you’re a professional in the audio field and not yet an AES member, please see the AES website for more information about joining. A large number of the AES journal articles and convention proceedings are now published for OpenAccess, so you don’t need to be a member if you would like to read those articles.

Growing Interest in DIY Audio Gear

DIY audio gear has seen a resurgence in the past few years, with a wide range of kits for use in home recording studios, guitar effects, and other audio applications available from lots of vendors. That’s why ABW began - to help people who were interested in building their own gear get started.

We knew that others doing STEM outreach programs as well as educators in music/audio technology were also looking for kits that would be used to teach the basics. Looking around, the low cost kits we found seemed to lack detailed documentation, as well as no guidance as to how to use them as part of group build. We also considered the people who were building these kits outside of a group build session; if they got frustrated or stuck because there was no place to go for help, then we would have failed to get people interested in more involved DIY audio projects.

The Metronome and Low-pass Filter kits were developed with the following requirements in mind:

Accessible for All Skill-levels

ABW has run a number of Learn to Solder workshops with both kits. Participants range from students to retired electrical engineers who were looking for a fun little project to do.

Organizing Group Builds

Yes - there are many small electronics kits that are available for purchase. However, what ABW has found is that people are reluctant to make the leap if it looks overwhelming - especially to someone who’s never picked up a soldering iron. By organizing a Learn to Solder session as part a larger event, people become much more willing to make the plunge.

ABW has offered sessions both where people have to reserve seats ahead of time as well as on a "walk in" basis. Other groups have organized events and asked ABW to attend to offer the learn to solder sessions.

For people interested in supporting STEM activities, we’ve created an event guide to help you plan out what is needed.
If you’re not part of a group already doing activities, we suggest checking in with your local maker space, as they probably have the facilities and enough soldering stations to hold an event.

Metronome kit building workshop during Crowd Supply's Teardown 2019.
Metronome kit building workshop during Crowd Supply's Teardown 2019.

Open Source Hardware

All materials, including both the design files and the documentation, are released under the Creative Commons 4.0 BY-SA license. You’re free to take these files and modify them to produce different hardware.

Tools Needed

Here’s a list of tools you need to assemble these kits:

About Soldering Irons

Cheap soldering irons don’t have temperature control and results may not be as good as with temperature controlled irons.

We’re sure once you do this project you’ll want to take on more, so go ahead and spend the extra $20 for a decent iron. In addition to the soldering iron you’ll need solder and some solderwick to deal with removing parts should you make an ‘oops’.

In the US, leaded solder is readily available and it’s much easier to work with than unleaded solder, so we suggest 67/37 Pb/Sn. Get the no-clean flux type as that will also make your life easier. Please follow all of the normal safety guides. Outside of the US you most likely will end up with lead-free solder, SAC305 is typically used. With the lead-free solder’s higher melting point it will be easier to damage the PCBs so please keep that in mind.

Setting Up Your Workspace

If you’re going to build on a regular basis you’ll want to have good quality tools.

When you set up your work area you’ll want to protect the surface you’re working on with a mat. A small fan to suck the fumes from the solder flux is also a good idea. Do not set up the fan to blow at you as that would prevent the joint temperature form getting hot and you’ll end up with bad solder joints.

If you have a local electronics store that sells parts and tools (there are a few left, in the Boston area we have three) it’s probably worthwhile to purchase there as you’ll get some advice. It won’t be as cheap as the online stores but you also avoid some of the uncertainty and most likely the kits sold at retail will be of better quality. Online you can find basic kits for $20 and ones that add a multimeter (very useful for finding problems) and a wider array of tools for around $40.

Manufacturing Plan

ABW has partnered with Crowd Supply and its network of suppliers to source the components for the kits. Crowd Supply will also handle all of the distribution. Except for the power switch on the metronome board, there are multiple vendors for all of the parts and we do not expect any problems making the kits available.

Of course sometimes things go wrong and that leads to delays in getting your order shipped. We’ll make sure to communicate status updates should Mr. Murphy pay us a visit.

In the Press

Hackster News

"Soldering is a great skill to learn, and ABW released a pair of kits that help build that skill... looks to be a great deal." "

Linux Magazine

"When it comes to DIY maker projects, if you don't know how to solder, your options are limited. Audio Builders Workshop remedies this with two kits, plus workshops, to give you hands on soldering experience."

All About Circuits

"[T]his project uses basic audio gear as a means for learning how to solder for the first time, or sharpen your soldering skills."

Ask a Question

Produced by Audio Builders Workshop in Boston, MA.

Sold and shipped by Crowd Supply.

Metronome Kit

One Metronome Kit. Assembly required. Includes PCB (blank), electrical components, 9 V battery clip, phone jack, and wire. Note: 9 V battery is NOT included.

$19 $8 US Shipping / $18 Worldwide

Low Pass Filter Kit

One Low Pass Filter (LPF) Kit. Assembly required. Includes PCB (blank), electrical components, 9 V battery clip, 1/4 phone jacks, power connectors, and wire. Note: 9 V battery is NOT included.

$19 $8 US Shipping / $18 Worldwide

About the Team

Audio Builders Workshop

Boston, MA  ·

Audio Builders Workshop (ABW) is a working group of the Boston section of the Audio Engineering Society. ABW's mission is to provide educational opportunities for anyone interested in any and all aspects of audio.

Brewster LaMacchia
Michael Swanson

See Also

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