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Janky Tape Echo

An open source, DIY tape echo effect for guitars, vocals, and synthesisers.

Real tape echo

This isn't a digital emulation, but instead a real magnetic tape echo that uses cassette heads and magnetic tape for lots of warm, crunchy, warbly echo. Add a lo-fi cassette vibe to your sound.

Indifferent Engine cassette echo

Made from readily available parts

The primary design principle is to enable the project to be built by as many people as possible, as easily as possible. All parts are selected to be easy to source online.

3D printed

Designed to be printed on any home FDM 3D Printer with a print area of 175mm x 155mm x 50mm or bigger using PLA, ABS or PETG filaments.

Janky Tape Echo code

Digital control

The motor controller is driven digitally by an Arduino Nano board. This allows for modulating the motor control signal for added warbles, flutters and wow using simple software.

Fully open source

​Want to make your own improvements and upgrades?


The design is fully open source, including all source CAD, Eagle schematic files, Arduino code and PCB gerbers. We also provide PCB blanks that have the jacks and potentiometers in the correct places to fit the 3D printed parts, so that you can easily make your own board layouts.


Make the design better and share it with the world. 

Licensed under GNU Public License v3.0

Indifferent Engine - Janky Tape Echo CAD
Tape Cassette


  • Cheap and relatively easy to fix yourself to keep it running. Break something? Print more parts at home!

  • Uses readily available cassette machine parts that can be found online. There are also no exotic electronic or hardware parts - we try to use easy-to-find parts like TL072 op-amps rather than discrete transistors that are becoming rare.

  • Uses simple cassette tape for making replacement tape loops

  • The design is free and open source. We sell PCBs on our merch store to make it easier for you to build and so that you can support the band. But, you don't even have to source a PCB from us - gerbers are provided for you to take to any PCB manufacturer - or to make your own boards if you know how.

  • Customisable. Want to make your own modifications? Perhaps add stereo, or an expression pedal or extra switches and potentiometers? It's entirely open source, so go right ahead. We even provide PCB blanks to make it easy for you to make your own customised boards.

  • 3D printed parts can be printed in PLA filament for easy home printing. All parts are also designed to print without supports.

  • Pre-printed parts and full kits are available on our merch store.


  • Requires more maintenance than commercially available pedals. Expect to have to change tape loops and perform maintenance yourself.

  • Requires a 3D printer. Any reasonable home FDM printer will do, but is a big expense if you don't already have access to one. Pre-printed parts are also available on our merch store.

  • It's big, for a stompbox. If you want something smaller, simpler and more dependable for your pedalboard then there are great commercial, digital pedals available that get a really good approximation of the tape sound.

  • It's really janky. Really. This isn't a clean sounding echo - it has a lo-fi, noisy cassette vibe. Even at minimum-jank this thing adds a lot of warble and character.

  • Complicated to build. It's not often that a DIY stompbox requires not just electronics, but software, 3D printing, moving parts and redundant magnetic tape media. There are a lot of challenges to making a working, reliable device. But, it is a lot of fun and we provide detailed build instructions.

  • Minimal direct support is offered by us. We provide instructions and videos and provide full kits, PCBs and 3D printed parts for saleso that you don't have to  make or source your own parts. But, beyond that, we only offer support via our discord channel. If something we've sold you is faulty, then of course get in touch via E-mail (reply to your order confirmation E-mail). However, we won't help you debug your rats nest of wiring or dodgy soldering job. If you're having problems with your build, head to the Discord channel where we're happy to answer questions and give general feedback and advice, as well as there being other Janky builders who might be able to help. Or, just come and say hi!

  • If we catch you selling these devices we will find you and force you to come to one of our floor shows where we can full-throat scream right in your sad little face.

Broken Cassette Tape
feral 1 nov 2021 (8).jpg

Have A Listen



You can download the project files hereEverything you need to make a Janky is the available for free.

You can also check out our GitHub page, if that's your thing.


Buy Stuff

If you'd like to support the band, we do sell some stuff you can use to build your Janky Tape Echo. You don't need to buy anything from us to make a Janky, but it'd really help us out. All money will go into making music and more open source pedal designs.

We have full kits available to pre-order. We also have PCBs, 3D printed parts, some fancy looking reels and acrylic windows which you can grab separately if you'd rather 3D print your own parts. If you are not grabbing a full kit, then you will need to find the electronic parts, cassette player and various other hardware pieces yourself - check the Bill Of Materials file in the project download for a complete list of all the parts and some helpful links to suppliers.

We also have some band merch - grab a T-shirt!


Build Instructions

A detailed build guide is available here.


It features a lot of images, so it might be a little slow to load.


Get Help

You can chat with us and other Janky builders on our discord channel. Ask for help, share progress and post pics of your build.

Note that the band only offer minimal direct help to people - we will help by answering questions and giving general advice on our discord channel, but we can't offer in-depth debugging support. Mostly we're trying to build a community of friendly pedal hackers who help one-another.


Join The Mailing List

Want to hear about new stuff before everyone else? Join the mailing list!


Where do I find everything I need?

The project is entirely open source. You can grab what you need from here. Alternatively, you can check out the project on our GitHub page.

​Do you sell assembled pedals?

No. We only build these for ourselves and - occasionally - for musicians we have played with or that we respect. Please don't contact us asking us to build you one unless your name is Omar Rodriguez-López. We're not hyper-libertarian capitalist gangster pirates, so we currently have no plans to sell completed tape echo pedals. Maybe in the future when we're hard up for cash.

Do you sell kits?

We have a pre-order open for this, yes. Check out our merch store.

Can I release my own version?

Yes - however, you must release it as sources and you cannot charge money for it. You must also credit Indifferent Engine, this is a requirement of the GNU Public License. Support the open source community, you scallywag.

Where can I find build instructions?

Build instructions are on this very website. Go here. They are very slow to load due to the huge amount of content.

How much does the janky tape echo cost to build?

That depends. If you already own all the tools needed and are building from scratch then we estimate that you can build a tape echo for between £150 and £200 UK pounds. This includes the cost of getting a PCB from us. This assumes you already have the necessary tools - for example, a 3D printer. If you want to make sourcing everything much easier, then you can buy a full kit from us for around £260 (check out the merch store) - however this obviously is more expensive as it includes our labour and profit. If you want to make one entirely yourself but don't have any tools, then it gets expensive quickly; 3D printers are generally pretty affordable these days - the printer we use most often is a Prusa Mini+ and can be had for ~£400. However, if you don't have a printer already that's a big outlay for a single pedal build. There are print-on-demand services worldwide that will print the parts for you, but be aware they are usually very expensive. When it comes to PCBs, it'll probably prove more expensive to make your own boards unless you have access to the tools to do it yourself, purely because we order boards in bulk. There are ways you can save money - for one you can source cheaper parts. The supplier we use for electronics is expensive, we use Mouser because they stock everything we need in one place and so it's simple to order. But, if you shop around you can get parts much cheaper than we get them for. You can also use cheaper filaments to 3D print with or use less filament (print with less in-fill). A good way to save money would also be to rework the electronics to use a cheaper microprocessor. The Arduino Nano boards we use are expensive - it's likely we'll look at reworking the digital electronics around something significantly cheaper such as a Pi Pico in a future update. You could do this work yourself, though. Open source, baby!

I'm having trouble with my build, where can I get help?

We have a discord server where you can chat with us and other Janky builders to get help and share tips and photos. The band are usually hanging around in there and will chime in with words of encouragement, however we don't offer in-depth support. Of course if you suspect a board we've sold you is faulty then get in touch - however, this is very, very unlikely. If you're having trouble it's almost certainly that you've made a mistake somewhere. There is also a debugging section at the bottom of the build instructions.

Where can I find tape heads?

Check E-bay, AliExpress, BangGood etc. Failing that - buy a broken second hand cassette machine and take the heads out of that. You'll need a read head, write head and erase head. Read and write heads are generally interchangeable. Erase heads are specifically designed for that purpose. You will only find erase heads in tape players that have a recording function. You need an active erase head - not one of those little passive magnet ones. Please don't destroy a perfectly good, working tape machine to just harvest the heads - there's loads of broken ones out there that can be recycled. The majority of broken machines are due to mechanical issues and so the heads are almost certainly going to be fine - maybe just give them a clean with some isopropanol.

Can I base my echo around a different tape machine than the one specified in the bill of materials?

In theory yes - but you would need to do some CAD work to make the 3D printed parts fit your machine. How extensive that would be depends on the machine you're trying to use. There's a rumour that these new tape machines that we use are based around the only transport that's still manufactured new. If that's true, then it means if you buy a brand new (not New-Old-Stock) machine, then it will have this transport in. So maybe it doesn't matter unless you want to use a vintage machine?

Why didn't you design this to use cassettes rather than a tape loop?

There's no simple way to include 3 heads when using a standard C cassette. Cassettes have 3 openings along the top to interface with the machine, but one of these would be used by the pinch roller that drives the tape through the machine. That leaves two spaces for heads. This means that in order to get the three functions we need - erase, write and read - you would need to find a single head that provided two of these functions. There are combined erase and write heads available which can do this job. However, in our experience, they are much harder to source.

Why didn't you board-mount the remote-switching jack?

Because we hit the maximum board size for the free version of Eagle. We're too poor to buy an Eagle subscription, but also want to keep the project free to develop for the open source community - if we keep the board size under the maximum size for the free version then anyone can develop new designs without needing a subscription. We provide PCB blanks that only has the jacks and pots on (so that the jacks and controls are in the correct place to mount on the 3D printed parts) for you to experiment with your own layout and own modified electronics.

Are you continuing to develop improvements yourselves?

Yes. We're also developing other crazy ideas, so give us a follow. We post frequently on instagram about new projects and music.

I'd like to make my own modifications, any ideas on what cool things I could add?

Yep, there's loads of scope to make modifications. You could make two devices and connect the Arduinos together over serial so that they can synchronise their motor speeds. Then you have a stereo tape machine - one for left, one for right. But why not just use one machine - as cassettes support stereo - I hear you ask? Well, because this way the left and right machines will run at slightly different speeds due to subtle variations in motor speed and will thus create a really cool stereo chorus effect. You could even add a control to increase the variation in motor speed between the 2 devices to widen the chorusing effect. Maybe make the 2 machines into one 3U rack-mount case for your studio? We provide extra pads on the PCB next to the Arduino for access to IO pins for adding controls - so, why not add some simple switches or extra potentiometers to change the janky-ness behaviour on the front panel? Or perhaps push the guitar signal into an ADC channel on the Arduino and use it to create an envelope follower that adjusts the delay time based on what you play? Or add an external expression pedal jack via ADC? Try allowing the user to use multiple read (or write) heads at the same time for interesting rhythmic effects. Why not reuse parts of the design to make a simple cassette-synth? Or any crazy cassette based thing you can imagine.

How can I support the project?

Just support the band. Listen to our music. Buy some merch. Consider buying your PCBs from us, grab a T-Shirt while you're at it. Come to a show when we roll through your town. Ask your local promoters to book us. Let us sleep on your floor.

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