I've read many threads. One thing is for sure - Where do I start?

  1. Get a case with a power supply unit (PSU). There's several brands to choose from and you decide from your budget.
  2. Get something that make sounds. VCO's - Voltage Controlled Oscillator - is a good idea. There is several brands out there.
  3. Get a filter. The sound of a VCO is very boring, however a filter makes it come alive.
  4. Get an ADSR - A: Attack, D: Decay, S: Sustain, R: Release. You will need one!
  5. Get a VCA (or two) with CV (Control Volt). A must have!
  6. LFO - Low frequency oscillator - in order to manipulate the sound from the VCO.
  7. Cables. 3,5 mm and in different colors - blue for audio and red for CV etc.
  8. Start making music!

Once you have this you can add modules: sequencers, multis (passive or bufferd), clocks, MIDI/CV converters, delays, reverbs...and more!
My suggestion: read about the modules you're interested in! Make a budget. You can easily go too far and end up with economically problems.

Good luck!


I would agree...up to a point. This would be a good course of action if MG didn't exist, and/or if dealing with a very limited build overall. However, given that we DO have this site as both a reference and a testbuild sandbox, there needs to be some prefatory points to that list...

1) Make your ModularGrid build bigger than you know it should be. This can then be pared down in size over time prior to making any move toward purchasing physical devices. Once you have that under control, then start considering cases, preferably ones that offer room to expand from your build's basic elements...because you're going to want to do that, eventually.

2) Two VCOs are always better, even if one is a simpler device and the other is more complex. The ability to detune, mix different waveforms, have one modulated and the other not, and the like results in a far richer palette of sounds. This doesn't necessarily require a separate mixer, also, as there are VCFs that have dual audio inputs available.

3) Some VCFs are not necessarily the ones you would start with. Your best bet is a state-variable VCF, which allows for low, high, and bandpass (and sometimes notching) in the same module, sometimes with separate outputs for each available simultaneously. Keep in mind that the VCF is the "timbral heart" of any synth, and that you will be playing it in of itself just as much as any other controller-connected device such as VCOs, etc.

4) When looking for envelope generators, there are actually two basic types: ADSR and AR (or AD, depending on how they treat incoming gates). Many of the latter have the ability to loop their envelope settings, also. It's also important that there are at least two EGs in a synth...one for applying to the filter for timbral modulation, and another for use with the main audio VCA for dynamic modulation. Technically, you can use one for both, but the results are far better with two separate ones under the same gate/trigger control.

5) VCAs: there are two types of these. Linear VCAs tend to be more useful for modulating the levels of CVs, modulating signals, and so on, and these also tend to be DC-coupled so that they can pass sub-audio signals. Exponential VCAs, however, are what's needed for best performance with audio, since human hearing responds to changes in apparent loudness as an exponential curve.

6) Modulation circuits come in more flavors than just simple LFOs. One can use looping AD envelope generators, which allows the user to define the rise and fall rates of the modulation curve. Then there are voltage-controlled slope generators, which are like those but which allow CV control over the rise and fall rates; these circuits are the backbone of such Eurorack staples as the Maths, for example. LFOs can also have delays, which allow the user to define the time needed for the LFO to reach full amplitude; this is useful to allow variable vibrato and/or tremolo effects depending on note length. This is also a situation where more than one is much better than just one, hence multiple-circuit modules such as the Maths, Batumi, et al.

7) Multiples are and AREN'T necessary...it depends on the build size. If you're only dealing with sending your pitch CV to two or three VCOs, you won't need a buffered mult. Those are useful when you have several VCOs (or other CV destinations) for the same CV and you'll need to regenerate that CV to prevent tuning issues due to voltage sags from the exponential converters in those modules. Also, if you have a small build and need every last hp for primary functionality, consider using inline multiples, stackcables, and so on instead of dedicated mult modules. But you'll invariably find that your build needs at least one multiple module, preferably something with at least a pair of 1 - 3 mults. And remember, you can't use multiples as mixers without a certain level of risk to any module that doesn't have diode protection on the output; mults are only designed to split outgoing signals, not to combine incoming ones.

8) You will need something at the end of your audio chain to attenuate your signal level. Synthesizer levels often exceed 5V peak-to-peak, and this is usually too hot for the front ends of many mixers. Either add a passive attenuator at that final point, or an output module that's designed for stepping the level down to proper 1.2 or .775V p-2-p line levels.

9) Colored patch cables are...pretty. And that's about it. As long as YOU know what you're doing in YOUR patch, it doesn't matter what color the patchcables are. This really only applies to systems such as Buchlas, where you have separate paths for audio and control signals...and in those cases, the cables are terminated differently anyway. Buy plenty of cables that you can afford, but don't splurge on decorative notions.

This is all based on some 40-ish years of experience of poking around with these things, across many years of their development...where some things have definitely changed, but many of these basics still remain the same.

There are some that would say that building a subtractive monophonic Synth using modular gear is almost missing the point. I don’t necessarily agree, but it raises the central and FIRST question you should ask: what is it that you want your modular to do? No one can tell you, that is for you to figure out and it very much determines what build you should explore.
I think that the extensive modulation options of pretty much every parameter in many modules offers unique sonic possibilities, even in a subtractive synth. In addition to the excellent points that Lugia made, consider that many well revered standard hardware synths use multiple envelopes and LFOs per voice: pitch, volume, filter at a minimum and that some of them are five or six stage (delay, attach, hold, decay, sustain, release). A four multi stage envelope module is ideal and XAOC Zadar reigns supreme here. LFOs also in fours (Batumi), so that you can get some tremolo and movement (pitch, volume, PHASE, PWM etc.).
That said, I personally would consider Zadar and Batumi a must for any monophonic subtractive build. Also, I’d second the SVF comment, albeit I would advise to also include one of the really interesting multi-mode filters, such as Three Sisters, QPAS, or Belgrade as they REALLY open up sound sculpting.
Lastly, Reverb and Delay are must have effects, followed by Chorus and Phaser. Classics for a reason. Also, here is where things get interesting, as you can do neato things with a sequencer and those parameters. At a minimum, add a decent multi FX (Black Hole DSP2) and Pamela’s New Workout. Sending a Euclidean sequenced saw to the reverb size can make for some interesting effects.

Now for the interesting and unique:
Sample based sound engines: 4ms Stereo Triggered Sampler and MN Morphagene. The former is better suited for pre-sliced samples (albeit you can experiment with start and length parameters) while the latter is just awesome for all sorts of sonic mayhem that involve dynamic playback speeds and slicing (including triggered) and cross fading. Both are excellent choices. Both can do granular synthesis, albeit the Morphagene with its dedicated CV control has a bit of an edge here.

Additive synthesis:
Audiospektri HG-16 is high on my want list for this purpose, albeit, I could see some of the FPGA based technology really take a hold here. XAOC Odessa should be interesting, but I’m really hoping for a true FFT based engine at some point (Fast Fourrier Transformation) with full control over the resulting harmonics. Any sound source can go in, like a sampler, but it is actually re-created using additive synthesis.

Wavetable synthesizer:
Preferably with custom wavetables to be loaded. The Piston Honda MKIII is a nice example of what can be done with this, particularly the CV controlled morphing. The more you like percussive noise, the more you need to look into this. Manis Iteritas and the other Wavetable Oscillators from Noise Engineering reign here.

FM synthesis:
Bring on the noise! Akemies Taiko and Castle. Harsh, metallic, mental. Love it, but I’m out of space.

Sequencers and clock:
The beating heart of your setup. Nothing comes close to Tempi+Rene MKII, albeit for percussion I’d suggest a Trigger Riot. These can be easily substituted for using a MIDI-to-CV module and whatever other sequencer you have. The Mutant Brain is a decent choice.

The unsung heroes:
It is ALL about generating and mangling CV. That became clear VERY fast to me. Hence, modules that attenuate, modulate, cross-modulate, and otherwise combine CV are the heart of what makes a modular unique. This has been my biggest epiphany since I ventured in head on. Half of your setup will easily be those types of modules and 2/3rd will generate and mangle CV without ever making a sound themselves.
Modules I love:
WMD Triple Bipolar - CV controlled attenuverter with three individual channels and a SUMMED out, also does fine work on audio signals
Noise Engineering Roti Polar - Four CV input attenuverting mixer (e.g. add two envelopes with opposing signs to get a bidirectional envelope to control the playback speed of a Morphagene)
4ms VCA Matrix - it’s big, yes, but it’s a CV modulated four channel CV mixer for all weird complex waveforms
Ornament & Crime - for the ASR alone
Branches - a dual Bernoulli gate: if you have two different timbral versions of a sound (two oscillators or two Signal paths) having a probabilized sequence of the two can be fun. Example: open and closed hi-hat in a percussive sequence
Marbles: still very much learning how to use it, but we all love happy accidents, don’t we?

The OP is building a simple monophonic synthesizer. Honestly, you'd be happier buying a TB303 clone or a Neutron. They are much more sophisticated than the OP build and a lot cheaper.

An oscillator, a filter, a couple of EGs and VCAs... there's no need to get into modular for that. Where modular shines IS the modulation. Pick-out and design your modulation FIRST then worry about oscillators and filters. You'll have a much better time even with the most basic of oscillators with some great modulation, than you will have with the most complex of oscillators that only have two EGs and an LFO to play with.

The most overlooked functionality are EFFECTS. Most synth patches sound pretty dull and dry without effects. But they seem to be an afterthought when people are first putting their kit together. Do NOT skimp on the effects. They are 1/2 of your sound.

Don't be afraid to be wrong. You'll make a lot of them. You'll have lots of modules you buy today that you'll regret (not deeply) later. Keep them around until you know you'll never touch them again. You'll also find the modules you curse today might be that special dash of seasoning later on.

Wellll...not just mod sources, tho. Knowing the oscillator (or better, "audio generator") compliment does go quite a bit of the way toward determining your modulation needs. Filters, VCA...those are sort of givens. But if you do a build with a pair of complex oscillators, these need different modulation schemes than would, say, a wavetable oscillator plus a very basic VCO for sound fattening. Or two (or three, or more) plain-jane VCOs in general. It's actually one of the stumbling blocks...when picking the audio gens, you do have to have part of your thought processes working a few steps ahead, and that's not always the easiest bit of multitasking.