Simple DIY synths you can build without soldering

Not just a toy: These synth kits are surprisingly powerful yet easy to build

In the early days of synthesizers, hobbyists and enthusiasts would grab a copy of Electronics Today, pore over some schematics and get soldering to get the latest developments or save money on high-end (or fun) instruments. These days, though there’s absolutely nothing stopping you doing that, it’s a lot harder to find the time or avoid the distractions for a big project.

You can still get a feeling of accomplishment by building your own synth from less complex kits, though – and you often get something that sounds bigger than the cost, too. This is a quick list (I’ve yet to review all them – but watch this space) of the projects you’ll find today.

As a musician, you may find an inspirational lo-fi sound, an unusually powerful synth, something that just clicks for a new pattern or just a distraction from endless presets and libraries.

Parents may find these engaging electronic and software tools perfect for STEM learning at home, as well as potentially introducing a love of creating music.

Either way, they’re affordable, accessible and fun!

Modal CRAFTsynth – two oscillator monophonic virtual analogue

Street price: £45 (rrp £79) – Gear4Music

Craftsynth

This unusual little three-dimensional puzzle looks simple – and it’s easily assembled in a few minutes, like a snap-together plastic model. It’s small, and the kit comprises 22 parts but doesn’t include a speaker of any kind, or battery holder (you can add one) – it does have a headphone socket and level control though, and a direct line-out.

An efficient user interface allows scales to be played, and sound can be controlled with presets on the synth itself. Some analogue-style knobs allow sound shaping, but it’s best when connected via USB to the Modal app, which opens up the synth engine fully.

And it’s a deeply impressive synth engine (read the full review) for less than £50 (current price from Gear4Music). In analogue terms, it’s got two oscillators, with six waveforms (both offer sine, triangle and saw, with Osc 1 adding PWM, and Osc 2 square and white noise) with mix, detune and FM; however, that’s largely to keep things simple.

It’s actually got eight oscillators…

An 8 oscillator monosynth?

To give the CRAFTsynth some of the punch associated with Modal’s analogue synthsizers, and introduce something far beyond the predictable ‘two-oscillator monosynth’ sound, it uses 8 oscillators grouped as four-per-voice. A similar architecture is used on the SKULPT and CRAFTsynth 2.0, very greater power and flexibility, and it’s exceptionally effective.

To fatten the sound without the sort of complexity you’d associate with such a complex source, there’s an unusual ‘spread’ control which detunes all 8 oscillators for remarkably complex, phase-shifting and evolving sounds. This mode can also form chords, working in conjunction with Osc 2’s detune amount, creating a surprising, full and pleasant sound for a simple £50 monosynth.

Sound is then shaped with two ADSR envelope generators and a MIDI-clock syncable LFO with four traditional waveforms, plus their inverse shapes, that can be sent to six destinations. A synthesizer without some sort of filter would barely be a synth at all, so there’s a state-variable filter that can do low-pass, high-pass or band-pass.

Want more? There are effects, too. MIDI-synched delay and waveshaping distortion. Approximately 10-15 minutes after the components are fished out of the box, this little synth has the potential to sound considerably bigger…

Did I mention this is £50 and could be assembled by most 10 year olds who can cope with Lego Technic?

The CRAFTsynth's power becomes more obvious when connected to Modal's app - on iOS, Android, Mac OS or Windows

Although a lot of DIY kits are focused on ‘getting away from the iPad’ – this is one that comes alive with something to control it, and Modal’s own app not only gives access to all the synth parameters, it makes them a lot easier to understand. It’s offered on desktop/laptop computers, iOS and Android.

It also gives access to virtual keyboards, sequencers and recording while interacting with a real synth – but you can play it as is, just add headphones or a portable speaker with line input.

If you don’t want to build it yourself, Modal also make a non-kit CRAFTsynth 2.0 – which has a different voice architecture and costs around £120.

Korg NTS-1 Nu:Tekt – high-quality synth + programming

Street price: £99 – find offers on Amazon UK

Korg NTS-1 Nu:Tekt synth kit

In recent years, Korg’s embraced the DIY community more than any ‘mainstream’ music firm, offering up kits of classic synths like the MS-20, as well as the low-cost Volcas and Monotron-type devices that are quite hackable, recreating the ARP 2600 and supporting the unusual Japanese Reon drift box synths.

The NTS-1 is something else, though, embracing the ‘out of the box’ cool that modern kit synths bring without the soldering iron stress or component sourcing. Careful selection of materials and a really clever approach to design means it feels like a surprisingly high quality gadget when finished, too.

It’s a simple enough project to build, with a single oscillator monophonic synth the result – at least, in theory. The NTS-1 is most than just a DIY box of bleeps. Volca and other ‘tiny synth’ enthusiasts will appreciate the sync in/out sockets, it has MIDI in via 3.5mm TRS and an audio input, too. The headphone output doubles as line-out, so it needs a bit of gain through a mixer – the opposite of the built-in very vocal and clear speaker!

A ribbon keyboard, with a configurable preset-interval arpeggiator, plays the sounds into three user-definable stereo effect slots, vastly expanding the sonic palette of the little synth (which isn’t that limited to start with, thanks to the NTS-1 Digital Kit). Aftermarket support is impressive, with many free, donationware or reasonably priced oscillator and effects modules that are also supported by the polyphonic synthesizers in the expandable ‘logue family.

Although the controls are simple, it’s got full MIDI over USB support. This tiny synth will easily add something to most project studios and given the flexibility of the programmable oscillator, multi-mode filter and stereo effects, it won’t be a forgotten gift for a musician like a monotron or similar might end up being.

logue SDK – programming synth components

Extending the capabilities of this miniature synth is a set of programming tools that’s not just limited to a £99 ‘toy’ – it’s the same system that supports the powerful prologue and minilogue xd synthsizers. You can download different oscillators and effect modulations with the included library program, dramatically extending the sound beyond a normal single-oscillator synth.

For very advanced builders, the logue-sdk (software development kit) is not user-friendly, but does provide an incentive to learn C/C++ and Linux software development tools.

If you’re looking at this from a parent’s perspective, you may need to provide some help and support getting started, but never underestimate what your kids can learn.

LittleBits & Korg synth kit

Street price: £139 to £169 – find offers on Amazon UK

LittleBits synth kit with Korg NTS-1 and SQ-1 sequencer

This one’s suitable for slightly younger electronics fans, and it’s relatively expensive for the scope of the sounds you’ll get out of it – but it’s very, very clever. LittleBits are electronic modules that snap together magnetically, and the Korg synth kit is part of a wider collection of kits that could, in theory, work together; synth sounds and robots? How much more retrowave do you need in one place?

The LittleBits synth components (pictured above in a custom stand, with NTS-1 and SQ-1 sequencer) include a decent small speaker, a couple of oscillators, a filter, envelope keyboard and mini sequencer, plus the bits to hook them up. Rather than waiting for me to review one (unlikely) – read this review on Sound on Sound for a thorough and fair overview of what you get. Ultimately though there is an element of reconfigurable invention involved, it’s closer to those old ‘electronic science projects’ you’d get from Tandy/RadioShack with springs, beepers and wires than a magnetic modular synth.

But the potential’s there for it to be much more, and it’s a very safe, comfortable way of introducing younger kids to electronics and sound.

Modal CRAFTrhythm – 8 track drum machine

Retail price: £99 – Gear4Music (not currently available).

Modal CRAFTrhythm is an 8-track sample-based drum machine that's surprisingly powerful

Following the mini-desktop format of the CRAFTsynth, the Modal CRAFTrhythm (read the full review) is the ideal partner for Modal’s mini kit synthesizer. It’s described as a sampler occasionally, but it’s a sample-based drum machine – there’s no ability to record with the hardware.

Although this sold out in June 2020, I’m leaving it here in case more stock appears, or another run is made.

It’s as easy to build as the CRAFTsynth, with slot-together boards and the option of battery or USB power (battery pack not included), and fully operational without needing to use a computer; just plug in headphones and play. For the price, it’s also surprisingly sophisticated.

There are preset sounds, but you can load your own CD-quality (16-bit, 44.1KHz – but mono) samples into the 15Mb of available memory, with up to 5Mb for a single sample – just under a minute. Samples are arranged into kits of 8 sounds, and you can have 8 kits – 64 sounds in total. If you think that doesn’t sound like much, remember that classic sample-based drum machines worked with a fraction of the space!

Each track has basic level and pan controls (the output is stereo, from mono samples), a dedicated adjustable filter with attack, hold, decay envelope, plus envelopes for pitch and level as well.

Astounding sophistication for a ‘kit’

Sequencing is handled by a traditional 8 track, 16 step grid, and you can have 16 patterns stored. Pattern chains of up to 16 patterns are possible, with repeats; combined with pitch adjustment, time stretching and sample speed, and the ability to automate four parameters, the CRAFTrhythm packs a huge amount into a tiny, and affordable kit.

Although the CRAFTrhythm is an inexpensive, uncased slot-together kit, it’s backed up by a deeply impressive desktop and mobile app – the same app that controls all Modal’s smaller synths. This user-friendly interface gives intuitive access to pattern chaining, sample library, time signatures and a full host of other deep programming options that would suit machines costing considerably more.

Plus it sounds good.

Parameter automation, or animation, in the CRAFTrhythm app

Naturally it’s controllable via MIDI over USB, and like the CRAFTsynth, has an easy-to-use app for programming, playing and saving presets via computer or smartphone.

Gear4Music also offered a bundle of both CRAFTsynth and CRAFTrhythm, which depends on stock levels.

Zynthian – advanced Pi workstation

Cost: Up to £299, depending on spec – direct from Zynthian

The open-source Zynthian project is a kit thanks to a devoted team who have pulled together several Raspberry Pi components to support a software-based synthesizer. It’s different from the other kits here, in that the kind of device you’re building and the power available (comparable to a higher-end smartphone or tablet) is more like gathering a set of software plugins for your computer – but it’s also a very rewarding, powerful project.

Zynthian kits come with everything included to build a versatile synth workstation, apart from a MIDI keyboard. Included is the Raspberry Pi computer, display, case, interfaces and audio interface, as well as a fitted carry case. You can choose less-expensive kits if you have some components or want to assemble and solder boards.

No soldering is required on the full V3 kit, but there are several electronic components to handle with care; most 13-14 year olds should have no trouble with it, and younger kids who are into electronics will really enjoy the results – but there’s an extra hurdle: software setup and configuration. You need to get a MicroSD memory card and install the Zynthian software, which will be easier with an HDMI monitor or TV and a USB keyboard and mouse.

The Zynthian’s included here because, in spirit, it’s a synth you can build without specialised skills, at home, and it’s got serious power, emulating several instruments at once, an effects unit, a sequencer and a sampler. It’s open-source and constantly evolving, and very actively supported too.

Teenage Engineering PO Modular – IKEA-style synthesis

Cost: POM 400 – £499, POM 170 £399

It’s pretty – but it’s also relatively expensive. Teenage Engineering stuff is rarely cheap – even the Pocket Operators have gone from £49 to over-£200 single-board synths – however, it is a kit, and it doesn’t require any special skills to make. It is also quite impressive, if you step away from the fact that you had to fold-it yourself.

Teenage Engineering has updated the modulars here – but the prices, and abilities remain the same. POM 400, POM 170 and POM 16 have improved assembly, better power supply management, PO-sync and other synchronisation improvements, better oscillator setup and improved controls, as appropriate to each model.

The PO 400 – above – is a proper scaled-down modular synth, plus it’s yellow which always goes a long way to making things good in my book. Construction involves folding the metalwork, which is an interesting change from the caseless or slot-together of most DIY kits, and a speaker and battery are included. It doesn’t have to be upright – the front panel can be installed so the modular lies on the back, angled up – and you can hook a PSU up instead of the eight batteries it consumes.

How it sounds is the main thing. Videos I’ve seen from Cuckoo, BoBeats and so forth all have one thing in common – it’s kinda thin and electronic-sounding in a way that I wouldn’t associate with an analogue modular. I’m sure it’s capable of much more, but mostly it reminds me of a box of angry Stylophones and monotrons – it would be nice to see some demos that allow sounds to evolve, rather than rapidly-sequenced squawks.

You’ll need some sort of CV controller to ‘play’ it, though there’s a sequencer built in – an Arturia Beatstep Pro, Keystep or almost anything else with CV output is better value. There’s no USB, no app, no… well. It’s a modular analogue synth.

There’s a smaller, more obviously synthy PO Modular too, the PO 170.

As you can see, there’s much less to play with, but it includes a sequencer keyboard arrangement.

Much as the TE PO Modulars are visually appealing, and easy to understand in terms of sound design, even without a review I know that there are much better projects out there, which will provide a more satisfying synthesizer at the end and more fun in building, too.

If the idea of a modular synth appeals, you could drop that £499 on a set of modules from Behringer’s new range.

Building a virtual synth – cheating?

There’s a lot more to building a synth – in the holistic sense – than slotting together some electronic boards and pushing a few kobs on. If you’re interested in the sound design and shaping, but not so much the mechanical bits, you can use virtual components to build a synthesizer from scratch entirely on your computer.

VCV Rack – virtual modular

VCV Rack is an open-source virtual modular synthesizer that lets you build a a Eurorack synth of immense potential on your computer. It’s both brilliantly simple, and infuriatingly fiddly, in that your library of modules is a logged-in account and you have to synchronise your computer to the account to add ones from the library.

VCV Rack is a free, open-source virtual modular synthesizer for Windows, Mac OS or Linux

The library of modules is immense, and premium models are reasonably priced; the layout of spaces, power bus and module designs makes conceptualising and playing a sophisticated synth before investing in hardware very easy.

Many modules are based on real hardware you can buy – there are over 2,000 modules in the library already, and the learning all focused on how to make sounds, not how to use the app.

It costs nothing to get started, but the scope of the display is almost too vast, with very small menus (and menus within a window on Mac OS). Niggles aside, this really is a no-brainer for getting into modular.

NI Reaktor – flexible synth toolbox

Native Instruments’ Reaktor is a great starting point for a hand-holding, commercially polished system – though it’s not cheap at £179. It’s visual, easy to understand and exceptionally powerful, with many commercial plugins coded in Reaktor’s environment and delivered with Reaktor Player.

Native Instruments Reaktor Player

Drag and drop blocks or go virtual-component level, construct a dream synth using a wide array of virtual modules, and then create something unique for your musical creations. It’s mature, stable and supported in Windows and Mac OS, and comes with a decent number of pre-built instruments and effects as well.

It’s theoretically possible to build an entire studio in Reaktor.

Arturia Modular V

if you just want to get a better understanding of how synthesizers work, without having to actually build the synthesizer entirely, Arturia Modular V is a good choice. It’s a replica of a classic Moog (plus a few extra modules) – the machine that defined ‘synthesizer’ for most of us, and you just connect the components the way you want. At €149, it’s an affordable way to get your hands on one of the most famous synthesizers in the world.

It comes with a full set of presets, as well, so it’s very user-friendly and educational, showing how the sounds are created as well as being musical from the start, where other processes will involve a lot of bleeps, squawks and high-pitched noises…

There are many options for this type of plugin, but Arturia’s polished GUI and great documentation makes it a safe and rewarding choice for absolute beginners as well as experienced producers. It sounds excellent, too – if anyone wants to lend me the real one for comparison, just get in touch!

You can get a similar experience on iPad from Moog themselves, with the Model 15 app for around £28.99

SynthEdit – program VSTs

SynthEdit is a Windows environment for creating virtual synthesizers that are compatible with the VST format used in Cubase and other applications. It’s relatively straightforward, and thoroughly proven – plenty of emulations of classic synths have been created in SynthEdit. It’s also relatively affordable, and you can sell the plugins you’ve created if they’re good enough (many people distribute their work free while learning, before moving on to develop more specialised, powerful instruments in other environments).

Csound – musical programming language

The living-dinosaur of virtual instruments is Csound. Don’t let me tell you the history and stuff – read the website – but it’s been around since 1985 and is a programming language for music and instruments. It’s quite complex to get to grips with, but a deeply educational process in terms of structure and benefits from knowledge of musical theory, composition, sound structure and synthesis alike.