A Guide To Starting A Eurorack Synthesizer System : Ask.Audio

Feel like surfing the rising tide of patch cables and joining the eurorack revolution? Here are a few things to consider before getting your feet wet. I recently went through this process and started my own system, and I thought it would be helpful to share the information that I gathered along the way. I’m assuming you already have a basic understanding of synthesis and CV if you’re here. If you don't then these video courses in The AskAudio Academy are worth watching.

A 2Egress 18U168HP case all filled up and ready for action!

The Intent

I think an important step in the planning process of your system is to decide what you hope to get out of your future modular. Do you want a monophonic synth, a drum machine, an effects processor, a complex modulation source, a companion to another piece of gear, or some other combination of these options? There’s no wrong answer, and you might change direction after you start your system, but it’s a good idea to have some kind of target in mind at the beginning.

Once you decide on your target, this will slightly narrow the range of modules you’ll need to research to make your system work. This will help you determine how large a case you will need, which will dictate your budget, which could in turn make you rethink your plan and start all over again.

Doepfer has a number of case options available

Unless you recently stumbled upon a suitcase full of money, chances are that when you start your system you’ll only be able to afford a few modules because the case and power supply will tap your resources (or at least that was my situation). Having a focus will help you buy the essential modules first and avoid some of the more exciting distractions out there. It’s tempting to gravitate to the more sexy and exotic modules, but you’re going to need some utilities to tie them all together.

Mixers, multipliers, attenuators, inverters, inputs, outputs, envelopes, LFOs and VCAs might not be as sexy as oscillators, sequencers, effects and filters but they are essential to providing a usable and flexible system. Conversely, it’s also tempting to pick up cheaper modules when you might be better off saving up for the big guys that offer broader functionality and superior sound quality.

1U Tile modules can offload utility functions to free up your 3U space

That being said, your intention will inevitably evolve with time. You might decide that the first batch of modules aren’t giving you the results you expected, or you might completely change direction once you discover a new module. This is the nature of eurorack, for better or worse. It has an almost unlimited range of customization. Speaking of customization, Mutable Instruments modules often even have third-party firmware updates available that can completely change their behaviour. But I digress…

Clouds and a few other modules from Mutable Instruments have third-party firmware updates available by donation from Parasites

Luckily, there is an active secondhand market for modules, and fairly low depreciation so you won’t take a bath if you end up deciding one of your modules has to go. In fact, a used case can be a good way to save a bit of money when you’re starting your system. Often cases will be outgrown and need to be replaced (or paired with new cases) so they do pop up on the used market from time to time.

The First Steps

Before you go all in, it might be worth considering getting something self contained. There are a number of options nowadays that provide great flexibility along with the potential to integrate into a eurorack system. Make Noise, Doepfer, and Pittsburgh Modular each have options for small complete systems, which can save you the trouble of sorting out everything individually.

Moog Mother32 Semi-Modular Desktop Synth

The Moog Mother 32 is a self-contained tabletop semi modular that offers a nicely functional analog synth voice with a sequencer. The Arturia Microbrute works great as a controller and has envelope and LFO outputs along with modulation inputs.

The Arturia Microbrute proves that good things can come in small packages

The Elektron Analog Four, while not exactly cheap, has some fantastic features, including a sequencer track devoted to CV, that make it a great modular companion. There’s also the Studio Electronics Boomstars which come in different filter flavours. You won’t get the same variety of patch points as most Eurorack systems, but it can be a simpler and cheaper way to get started.

SE Electronics Boomstar in its blue Arp flavour

Generally, I find starting small and expanding slowly is the best way to go. By adding one module at a time you get a chance to really thoroughly understand one piece before adding another. Often when people get too many things at once they don’t dig in to the same degree and end up missing out on interesting features. However, if you are trying to create a monosynth you’ll want to make sure you have the necessary components: Oscillators, a filter, an envelope or two, an LFO, and a VCA. You’ll probably also want a mixer of some kind, a multiplier and some sort of trigger source like a sequencer or midi input.

Intellijel’s Audio Interface II lets your system interact with the outside world

Bear in mind that eurorack signal levels are much hotter than line level. Therefore, you should attenuate the signal somehow before plugging your system into any line level gear. If you just plug a set of headphones into an oscillator you’ll get a very loud output in one ear (and possibly tinnitus!). Conversely, if you want to run something external through your system, you’ll need to boost the signal first to get it to an adequate level. There are a number of modules available made specifically for this purpose, such as Intellijel’s Audio Interface II

The Size

Elite Modular has some beautiful larger cases

Knowing what you want out of your system will help you determine how many modules you’ll need to accomplish your goal. Most experienced knob twiddlers will advise you to get a bigger case than you think you’ll need, or you’ll risk quickly outgrowing your available space. Eurorack size is measured in U vertically and HP horizontally. 1U is the standard size for a single piece of rack-mounted electronic equipment and is equal to 1.75-inches (or 44.45 mm). Most Eurorack modules are 3U in height, but there are a variety of 1U tile sized units out there (just be aware that Doepfer and Intellijel tiles will not fit in Synthrotek or Erthenvar cases).

Intellijel’s 7U cases feature a strip for tile modules

I’ve heard HP described as both horizontal pitch and hole points, either way 1HP is equal to 5 mm. Hole points always made more sense to me because it corresponds to the number of spaces available in your rails for screws. The most common sizes are 48HP, 84HP (which is the same width as a 19” rack) and 104HP.

Pittsburgh Modular has a great little desktop 48HP case

Having used both a modestly sized Doepfer A-100 and a small 48HP case, I opted to get a 6U 104HP case and felt that was a good compromise. Big enough that I could make a decently functional unit, but small enough that it wouldn’t completely dominate my space and be impossible to move. Because I have an Arturia Beatstep Pro, a MicroBrute, and an MFB Kraftzwerg, they allowed me to offload some of the tasks that I would otherwise have to accomplish in Eurorack. I also felt that a size limitation would prevent things from getting out of control (hopefully).

Dark Modular made a case specifically for HP Lovecraft fans to summon eldritch tones of indescribable horror

The Case

Your case is probably the aspect where you have the widest price range. Cases can be exotic, ergonomic, portable, expandable, and sometimes beautiful. Or they can be more simple and utilitarian. Of course there’s always the option to make something yourself if you are so inclined. You can even shove them in cardboard if you want. Tip Top’s Happy Ending Kit is probably one of the most popular cheap options, and Art For the Ears has a similar alternative. Basically you get a set of 84HP rails, and a set of end cheeks that can either sit on a desk or be mounted in a 19” rack enclosure. This gives you the option of having something stationary or potentially portable. Intellijel, Art for the Ears, and 4MS have clever options for expansion by adding additional skiffs or boats. Some companies only sell cases with power supplies, some without, and some offer power solutions separately.

Art For The Ears rack mountable ears sit nicely on a tabletop

The rails of the case are where you screw in your modules. Some rails have sliding nuts while others use threaded nut strips. Strips are far less fiddly as you don’t have to slide the nut into position before you install a module. You also don’t have to worry about running into the mistake of finding all your sliding nuts on the other side of a module and having to disassemble everything before you can install your new module. Strips aren’t a lot more expensive so in my opinion it’s worth it to get them and save yourself the potential headaches (especially if you’re as clumsy with your tools as me).

Synthrotek’s Deluxe Power Module offers the often underestimated feature of the cool skull graphic

The Power

The power supply for your system is a commonly underestimated and misunderstood part of the equation. Some manufacturers sell power supplies separately, sometimes even as kits, so you can provide your own case and power it. Some cases integrate the power supply and connect in a more discrete location on the side or back, while others require a 1U or 3U module space to be connected on the front. Some have you connect your modules directly to them, and others distribute power through boards or ribbon cables. Modules potentially require power on three voltage rails: +12, -12, and +5. It’s important that your power supply provides enough amps for all your modules on each voltage rail. Underpowering your modules can cause them to behave erratically (even more so than usual!) and can potentially damage them.

4MS has a clever means of expanding on their power system

When you buy a module, it will usually have the ribbon cable attached. You’ll notice a red stripe on one end of the ribbon cable, this is to mark the -12V side. Different manufacturers use different labelling schemes. You might see Stripe, or Negative, or -12V or Red, and both the module and power connection use the same orientation. In any event the cable should only fit one way, so there’s nothing to worry about, right? Mostly right. In some cases you might get a misaligned ribbon cable so it’s a good idea to check it before plugging it in, firing it up and potentially frying your new module that you’ve been waiting to try. Most manufacturers take measures to protect their products from this scenario, but not all do, so it’s better to be safe than sorry. On the plastic header of each side of the ribbon cable you should be able to see a small triangle, which should align with the red stripe. If it doesn’t, you should refer to your manufacturer to make sure everything is correct before proceeding.

Intellijel has differently sized power supplies with differently sized robots depending on the size of the intended case.

If you want more detail you can check this out: https://www.muffwiggler.com/forum/viewtopic.php?t=15109

Here’s a breakdown of some of the available power supplies sold separately.

There’s also a far more thorough collection of power supplies and specifications here: https://docs.google.com/spreadsheets/d/17qu-PkyJnjZf9YzhNYy7X7-d-lmZqhahyUW0YM1b2N0/edit#gid=0

2Egress has some striking case designs and gives you the option to buy them with or without power

The Community

If you’re feeling confused after looking at those power specifications, fear not! Modular Grid will calculate your requirements and warn you of any potential issues. It’s also a handy way to plan your system because you can create a virtual rack and play with different arrangements without having to reach for a screwdriver. They even have an “Optimize Rack Space” function that will make the most of your HP and might allow you to squeeze in another slim module. Or it might make you come up with new patching ideas. You can search for modules by type, manufacturer, and specific HP sizes, as well as check out descriptions, pictures, and videos. There is also a marketplace and forum where you can discuss, buy and sell modules. Overall it’s a pretty essential resource for Eurorack and I highly recommend it.

I still don’t get the connection between cats and synthesizers, but it’s there

For better or worse, the Muffwiggler forums are like Gearslutz for Eurorack. Forums can have lots of helpful information and they can be a great place to have your questions answered, learn about a product you’re thinking of purchasing, or discover new inspiring ways of using things you already have. On the other hand, they can fall victim to the usual pitfalls of forums.

Recently I’ve found the Eurorack Facebook groups to be a friendly, welcoming, and informative environment with more tolerance of n00bs. Plus, the Canadian Modular Synth Exchange is a great group for canucks to pick up modules second hand or pass on units that need to make room in the rack. Facebook identities force a certain level of accountability that forums lack.

Facebook Eurorack Synthesizer Group: https://www.facebook.com/groups/403937676290574/

The Conclusion

Starting a Eurorack system is not an undertaking to be taken lightly, but I think a lot of people think it’s more complicated or daunting than it really is. It’s certainly not cheap, but neither are the best synthesizers on the market. Eurorack offers a level of flexibility impossible to achieve with fixed architecture synthesizers, and an unparalleled sonic quality. Presets are not possible, but I don’t think any user really laments their absence. I find creating patches to be an almost meditative process. I love observing as a sound takes shape and experimenting with new layers of modulation and hearing the results. The ephemeral nature of these patches is part of the inherent charm of the medium.

Scentury Cedar sells custom wood cases on Etsy

If you do decide to start a system, remember that at the end of the day it is YOUR system, and it should function the way you want. While it can be helpful to get advice from more experienced users, take it with a grain of salt and decide what will work best for you. If you want to make a 9U 104HP rack of Distings in a gutted vintage radio, go for it!

Hopefully you’ve found this guide helpful. If you have any questions, if there’s anything I’ve missed, or if you have any gems of wisdom to share about starting a system, I encourage you to post them below.