If you're Eurorack curious but short on space or cash — or simply allergic to 3.5mm patch cables — Softube's Modular might be for you.
Softube's Modular plug-in has been around for a couple of years, but has recently enjoyed renewed attention with some exciting new modules and excellent price deals. Competition has also hotted up in the virtual modular market, so now seems like a good time to take a deeper look.
Modular's concept is simple: it's a virtual Eurorack synth environment in a plug-in (VST, AU, AAX). It behaves in software just like its hardware equivalents and features movable modules, front-panel cable patching, and integration with your host DAW via virtual MIDI/CV/clock converters. Like other Eurorack sims, Modular seduces with the possibility of building a modular synth at a fraction of the cost of hardware, and with instant patch recall and the chance to start afresh whenever you want. But can software really capture the essence of the Eurorack experience?
Click & Collect
The basic Modular plug-in includes a selection of core modules to get you started. You can then expand your palette by purchasing additional individual modules. The base package is very inexpensive considering how much is included. You get all the modules you need to integrate with your DAW and external hardware, and a slew (sorry) of utilities, sequencers, mixers and performance panels. The core synthesis blocks — oscillators, envelope, LFO, VCA —are direct simulations of several ubiquitous Doepfer A-100 series modules and are also included as standard.
A number of add-ons come from Softube themselves in the form of 'modularised' versions of their plug-in effects. This includes the TSAR-1 and Tube Delay, which just happen to be my go-to reverb and echo plug-ins. Softube have also broken out the separate voice modules from their drum machine plug-in Heartbeat. The Softube extras are not sold separately for Modular, they are 'Modular-ready', so if you buy the plug-ins you can also use them as modules.
Perhaps the biggest appeal of Modular is the availability of several third-party add-ons that are faithful ports of real hardware modules. The range isn't huge, but it's very high quality, with some killer modules from Intellijel, Mutable Instruments, Buchla, 4ms and Doepfer. You might not be able to buy a Clouds hardware module any more, but you can now have it running as a plug-in.
Plug Me In
Modular doesn't have a stand-alone app, it's inserted as a stereo instrument plug-in in your DAW of choice. (There's also an FX variant of the plug-in if you want to process audio from your DAW). A fresh instance of Modular presents you with an empty rack, and a palette of all your modules. In most cases you'll start with some selections from the 'DAW and MIDI Interfacing' section, in order to get MIDI and/or clock in from your DAW or further afield. Audio outputs, on the other hand, are built into the 'case', along with Modular's mode buttons. There's a main stereo pair that routes directly out of the plug-in, and four further aux outs that can be picked up by other channels in your DAW.
You could just dive in and start adding modules, but Modular has another option that you won't find on your real-world rack: presets. There's a built-in patch browser, but I was pleased to see that the native VST and AAX preset systems are also supported. The on-board browser is tag-based, so lets you search by sound character and which modules are used in the patch. Factory presets using paid-for modules are also distinguished by name. Patches can have custom icons and info text, and can be rated.
Spending some time with the library is a good way to get a feel for what Modular is capable of. There's an awful lot to explore, covering lots of classic synth sounds, sequences and drones, and some Heartbeat-based drum machines and grooveboxes. It's a great learning resource for newbs and experts alike. You can pick apart and reverse engineer other people's patches, picking up new ideas and possibilities to break out of your own patching comfort zones.
After some preset browsing I was suitably reassured that Modular is the real deal sonically, not to mention inspired by the cunning patch wizardry on offer and keen to try with a blank canvas. After dropping in the obligatory MIDI to CV converter, the obvious place to start was the Doepfer VCO from the standard toolkit. This is the familiar, versatile A-110 oscillator featuring multiple shapes with discrete outputs, sync, and pulse‑width mod.
Continuing down Predictable Avenue I added the Doepfer VCA and VCF. Making connections follows the tried and tested click-and-drag convention. While you're holding the mouse, suitable patch destinations light up green. Cabling stays hidden until you hover the mouse over a port. Though there are mult devices available, you don't need them to patch from a source to multiple destinations. Thus you can freely connect gate, note and clock, etc, from your MIDI interface modules to anywhere they're needed.
I put together a fairly standard 'My First Patch' arrangement (see screen) so I could get a feel for the system and how responsive the sound is. After lots of tweaking I concluded that the sound modelling is definitely complex and dynamic. At least with these Doepfer modules there's a distinct non-linearity to the results, with both the VCA and filter sensitive to the level and frequency spectrum of the inputs.
With a handful of modules in my rack, the plug-in window started to feel cramped. On my MacBook Pro the plug-in window defaulted to viewing about one and a half rows in height, and in the region of 80HP across (eight Doepfer A110 VCOs). I really wanted to see at least two rows without scrolling around, but you can't manually resize the window. Instead Modular chooses a fixed window size based on your screen resolution. With my retina MacBook Pro at its default resolution (equivalent to 1680x1050), Modular stuck stubbornly to its smallest size.
To get the window size to bump up to the next level I needed to switch to 1920x1080, or plug into an external display and relaunch. This then showed two rows and a wider range. There are some cryptic settings for limiting the size to Small or Medium on large screens. It took me a number of experiments and relaunches to figure out that Medium was the biggest I was going to get, and there's no way to force this at lower resolutions. Why not just allow the window to be resized freely? It's not like the contents needs to change, just the visible area.
Even without using the optional extra modules Modular has plenty for a huge range of possibilities. The A-100 modules take care of the main palette of VCO, noise and randomness sources, envelope generator, LFO and ring modulator. These modules have been the foundation of many an IRL Eurorack case. There's also a simple sine source among the huge bank of basic grey utility modules.
There are four-input mixers for audio and CV, a crossfader, and a Polarizing Mixer that can be used as a general purpose four-input attenuvertor. There's a panner module, but no stereo mixer, which can be limiting when trying to incorporate stereo effects. Rather than lashing something up with multiple mono mixers, I tended to run effects directly out of the stereo auxes and balance using my DAW faders. This is great, though if you save this patch it may not have the supporting routing structure when you recall it in another project.
There are no fewer than four built-in sequencer modules. Traditional CV sequencing is taken care of by 8‑ and 16‑step modules with variable pattern length and on-board chromatic note quantisers. A dedicated quantiser module is also provided for constraining to custom scales. Longer sequences can be created with multiple sequencers and some clever patching of resets and logic gates.
The circular Penta sequencer offers an alternative approach, and percussion sequencing is handled by a four‑lane, 16‑step trigger sequencer. Polyphonic patches are facilitated by a Quad MIDI to CV module, providing round‑robin management of up to four voices.
Rule Of Thirds
Inevitably the shiny third-party modules that Softube had kindly unlocked for me proved too tempting to ignore for long. The Buchla 259E is a highlight, offering a huge and wonderful range of sonic fodder, not to mention modulation sources for use across your rack. This pairs nicely with Doepfer's optional A-101-2 Low Pass Gate for West Coast synthesis styles. The 101-2 is also noteworthy in that it was modelled on multiple units, and adds a switch for selecting been three different vactrols with different characters.
A personal favourite is Intellijel's Rubicon, an incredibly malleable FM playground with the ability to slow its waveform down to zero and back the other way. I also love the Korgasmatron, ostensibly a dual‑filter module but a seriously gnarly FM sound design workshop in its own right. I'd also put the 4ms Pingable Envelope Generator down as an essential, giving you a brilliantly versatile and playable function generator.
On the digital side are Braids and Clouds from Mutable Instruments, both of which are no longer available to buy as hardware modules. Braids is a really useful, multi-algorithm sound source. Clouds is the much beloved granular texture synthesizer that kind of became the sound of modular for a while. Overused or not, I love it. Yes, you can get a Max For Live version but it's great to have it in its original form and available in all your hosts.
Modular is not all straight-up emulation. One thing that Softube have added to the pot is a system of performance macros. These are provided as a set of modules that you can use to create a custom control panel for your patch, with key parameters collected into one place.
Several different combinations of knobs, faders and switches are provided, plus a level meter and signal LED. A single control from any modules in your patch can be mapped to each performance control, and you can customise the control range with maximum and minimum settings. Setup is straightforward, and mapped parameters are indicated by colour, though not colour-coded to their macro.
This is really useful for making large racks playable, and has been utilised throughout the factory presets so that you can get tweaking and sound shaping without understanding how a patch works. There is room for improvement, though. For a start it would be nice if you could map more than one parameter to a macro. And, frustratingly, after mapping a control to a performance module, you can't change it directly.
The Performance panels are a great touch, but MIDI control of Modular's parameters is a little lacking. There's no MIDI learn feature for assigning CCs to hardware controllers. The basic MIDI to CV module includes Mod Wheel and Aftertouch, but no other ways to bring CC modulation or control in. Thankfully all parameters in a patch are available for host DAW automation. If you use a controller or host that controls via automation instead of MIDI (eg. EuCon, Native Instruments) then you're in luck. In fact I found the best Modular experience was running hosted in Komplete Kontrol or Maschine. All the factory patches are NKS ready, have audio previews, and meticulously mapped controls with pages for each module.
Modular is currently the closest direct simulation of Eurorack available in a plug-in. It sounds fantastic and offers many modules that are virtual recreations of real (and choice) hardware modules. As well as a synth, you can use Modular as an insert effect, so it adds an experimental signal processing toy box to your DAW. There are some basic things that would make Modular better to use, such as a freely resizable plug-in window, and more MIDI modulation and control possibilities.
Softube make it clear in the manual that you can't fully replicate the physical experience of using a modular synth in software. Using a hardware synth puts you into a different headspace, there's a relationship between your physical movement and the sound that forms a more direct feedback loop.
There is, though, a lot of upside in the form of patch saving and recall, DAW automation and portability. You can rebuild your rack any time and use multiples of any module (although there's a danger that you only ever scratch the surface of things). But it's not a zero-sum game — if you're a hardware Eurorack fan, Modular is great for prototyping new ideas or purchase options, and there's always the possibility of connecting the software and hardware domains via a suitable audio interface. Above all, Modular makes modular synthesis accessible to many more people, and at a much lower cost.
Competition in the Eurorack sim arena comes primarily from VCV Rack. This is a stand-alone app which is available free, with an open ecosystem of both free and paid-for add-on modules. More Mutable Instruments modules are available here, although they're disguised as 'Audible Instruments'. VCV Rack has a great UI and sounds the business, but integration with DAWs is via a bridge plug-in and less straightforward. A recently added Host module allows VST plug-ins to run inside the Rack.
Another newcomer is Voltage Modular, which works in much the same way as the others, and offers an easy route in for third-party developers. It has some clever UI features that aim to side-step some of the usability issues in other software modulars. It has its own graphical style that I'm not fond of, and I'm not convinced that the sound is quite up there with the competition yet.
Reaktor Blocks was the attempt by the daddy of software synth environments to create a Eurorack-like platform. I still think it's sonically in a class of its own, but has been held back by lack of easy cable patching. Rumour has it, however, that NI are working on an update with true front-panel patching.
- Works exactly like a modular, inside your DAW.
- Official emulations of real‑world modules.
- Can be inserted as an effect to process your DAW tracks.
- Great NKS support.
- No MIDI learn or general CC control implementation.
- Frustrating fixed window size system.
Modular is the closest simulation of Eurorack you can get as a plug-in.