This is the first concept for my eurorack synth. I plan to build the rack over the course of 2019. My plan is to gradually buy modules and getting to know them before buying more modules. Along the way there will be probably be many adjustment and changes. Nonetheless this is my first concept based on videos I saw on the net and some advice I got from people.

My aim is to be able to generate percussive and rhythmic sounds/loops as well as melodic synth sounds.
As you might notice from looking at the top 1u row, this is most likely going to be built into an intellijel 7u rack.

Any suggestions or changes needed? What do you think?

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One thing that comes to mind: with as many clock signals as this will have going on, you should look into some logic modules to create more intricate behavior with the gates you'll be using. On a similar note, a couple of comparators would also come in handy for similar reasons...you can use those to derive gate on/offs from CV levels coming out of the Stillson Hammer, for example. Maybe take the Switch Matrix out for some of that, potentially adding a much smaller thing like a Doepfer A-151 to swap sequencer CV outs to create longer sequences. Maybe toss out the uScale, also, since the Stillson has some potent onboard quantization. You can also recover another 4 hp in your top row by swapping the Maths out for a pair of Doepfer A-171-2 VC Slope Gens (basically they're akin to half a Maths each, minus a few extra jacks that you can work around). Even more space can be regained by swapping the Rings and Tides for Codex Modulex's 8 hp versions of each. See how much space you can get back by doing things like this; empty space eventually = more modules, after all! ;)

How do you intend to mix your audio signals together? The Quadratt has four inputs and they are simply mono.

@Lugia: I'll definitly design a rack with the modifications as you suggested and see where that brings me. I'll post it here once it's done.

@Ronin1973: You're totally right, that's something I'll have to take into account. Although, the Veils also acts as a mixer. So wouldn't it be possible to take the mixed output from that and route it to one channel in the Quadratt, or am I misunderstanding how the Veils actually works? If it works this would give me 7 channels to play with.

Do you think it's also a good idea to have the shakmat time wizard and the pamela's new workout, seems there's quiet some overlapping in their functions?

Veils functions similar to the Quadratt EXCEPT you have CV control of each output volume. I wouldn't define either of these as a proper mixer, though you can use them as basic mixers or submixers. I would think about all of your outputs (drum modules, FX units, etc.) and figure out how many audio signals you might want to mix together at once. With eight "mixer" inputs (seven if you're cascading one unit into another), you're going to probably be short when it comes to a complicated patch.

Look into the Roland 531, Happy Nerding PanMix, Pittsburgh Modular Lifeforms System Interface, and Blue Lantern Stereo Sir Mix A Lot. All of them are 6 input mixers with pan capabilities on all/most channels depending on the unit. With exception to the Blue Lantern, they all have headphone outputs as well.

You probably won't need a decent mixer to begin with. The Quadratt and Veils will be enough to get you going. But as you start to flush out your case, you'll probably want one.

Yeah...while the Time Wizard does contain some logic capabilities (albeit not on the same level as a full-on Boolean gate setup), for the most part the Pam's does what it does. The question would then be whether you'd get more mileage out of the additional functions the Time Wizard offers versus the extra two channels of trigs on the Pam's. But...also, have a look at the Pexp-1 and 2, which are expanders for the NEW Workout and which offer some functions that need to be considered.

My performance mixer fave as of late is different from Ronin's. Qu-bit's Mixology is a four-in, stereo-out...but offers CV control over per-channel level, AUX send, and pan, with a proper AUX mono send and stereo return, which means it plays nicely with reverbs, choruses, and most other FX that tend toward that routing. You also get manual solo and mute per channel as well, which can come in handy when programming complex patches.

As for the Veils, tho...again, Codex Modulex shrank that down to 8 hp and brought the price in cheaper. So ultimately, you could add a pair of those for a hair under $300, giving you eight VCAs with variable response curves, potential submix abilities, and a compliment of VCAs of that size would then easily allow you to CV level control both audio and CV, again upping the potential complexity.

I re-organized some things in the rack based on your advice.
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  • I replaced the mutable instruments with their codex modulex counterparts, adding a second 4xVCA.
  • Removed de Shakmat Time Wizard (because some redundancy with the Pam's new workout)
  • Removed the sequential switch matrix
  • Added the mutamix (doesn't necessarily needs to be that one)
  • Added a 2hp switch
  • Added the Kinks
  • Added 2 doepfer A-167 comparators
  • Added 2 doepfer A-171 slope generators

What do you think?

Also, about the doepfer's, could you elaborate a little? I understand how they work and what they do, but I'm not sure how to use them withing a modular setup. Many resources online explain their basic functions but don't explain what the advantages are of having them in a rack.

Get rid of the Mutamix since you have two u4xVCAs and replace it with the Happy Nerding PanMix. Now you have a stereo mixer with a headphone out built in. You can get rid of the Intellijel Headphone Out and the blank panel and pop in another Intellijel buffered mult or the Intellijel ZeroScope.

Also, you're 1HP over on your bottom row.

Yep...the PanMix or the Roland 500 series output mixer are decent choices here since you have ample VCAs now to handle your input levels.

The Serge VCS (the originator of the Doepfer A-171-2) is a very prized module. It can function as a slew limiter, an envelope generator, a LFO, a VCO, and probably a few other things that just aren't coming to mind right now. Ken Stone took the original Serge design and added a few tweaks, then Doepfer took Ken's design and did a couple more. It's literally a "Swiss Army Knife" module. MakeNoise's Maths is pretty much two of these under one panel (making the Maths more like the Serge Dual Universal Slope Gen) and added a little bit of logic/arithmetical function voodoo...but it's also 4 hp larger than a pair of A-171-2s, and the additional functionalities are easy enough to replicate on your own.

Basically, what you're looking at is a pair of CVable slews...rise and fall...with the ability to change the slew rate via any sort of incoming modulation. Feeding this with an existing CV results in portamento-type behavior, but with the ability to voltage control the rates. Now, that's where it gets weird, as the module can also output its own CV that rises and falls according to the slew rate levels. This can be done as a one-shot on a gate/trigger, making the module behave like a 2-stage envelope gen...or it can be looped, making it act like a LFO with a user-defined waveform via the slew rates. But it gets even crazier, since the Exp CV point accepts 1V/8va CV just like a VCO...and then you have a VCO with a user-definable waveform. Oh, and since you can feed the slew rates separately, you can make that waveform shift all over the place constantly, yielding some wild waveshaping action that most average everyday VCOs cannot match. And those are just for starters...with a couple of additional modules of various sorts, you can make these act as a little analog computational "brain", bouncing their functions of of each other and outputting loads of modulated CV craziness. This last bit is what the Maths is best at...but you can get there with a pair of A-171-2s, an adder, maybe a comparator or two and some simple Boolean logic, and wind up with a little more user-definability than the Maths. Fun!

Thanks for the detailed explanations, really appreciate it. Following both your advice I switched the mutamix with the panmix. Can't wait to get started with it.
As I said in my first post, this thing is gonna be built at a slow rate, mainly because I wan't to get to know my modules first before buying some new ones. Any suggestions on which ones to buy first? Some starting combinations that might provide some great fun in the beginning?

The rack now looks like this
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Ah...one more tweak, this time for the comparators. Jettison the Doepfers and use the Joranalogue Dual Window Comparator instead. Not only does this jam both comparators into the space one Doepfer uses, these are WINDOW comparators...which means they can trigger gates from several different comparator states (below, in window, not in window, above) instead of simply one via a combination of the comparators themselves and some logic onboard the module.

First modules here, I'd say: the entire tile row (may as well have that in place, since its your main utility set), uRinks, uMotion, Kinks, A-171-2s, Sisters and Stillson Hammer, just to get your basic synthesis functions in hand. Last in should be your drums and sampler players...because you may find things along the way that suggest to you that 1) you might not need them and 2) there are ideas emerging from your discoveries with the synthesis aspect that demand a shift in module implementations.


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On another note, do you have any opinions about codex modulex being an exact copy of mutable instruments modules? I saw some discussions online about how the creator of Mutable Instruments is not happy about those copies. Apparently the initial intent of releasing his code open source was to share the knowledge to the community but not for having other companies making profit of his work by simply copying his stuff. I'm not sure how I should think about that.

Anyway, just for the sake of trying, and as I was left over with some space I tried putting some of the original mutables inside the rack. Although I had to ditch something and for now removed one doepfer A-171-2, although I'm not quite sure what the overall impact will be. I still have 8 vca's but now it's one from mutable and another from codex modulex.

Here's that rack:

ModularGrid Rack

Still not bad, even with the extra space taken up by the MI modules.

My take on the Mutable thing is this: if Olivier comes out with a successor device (as in Plaits succeeding its predecessor, Braids), that would tend to indicate Mutable's signed off on those earlier designs, so copy away. I do see his point about the currently-active parts of his line, though...but at the same time, there's two points that nag at me. First up, the main reasons why I myself would use the Codex Modulex clones would be 100% based on their size. If Mutable could give me a Veils in 8 hp, I'd certainly rather have that...but Veils fits in 12, and when you need to cram functionality into limited space, hp count is everything. After all, it's why 2hp and Erica's PICO series seem to turn up in a vast amount of builds...people get that point.

The second thing is that open source insistance. Several years back when there were far fewer Eurorack manufacturers, that philosophy make way more sense. But now, in times where massive retailers such as Thomann and Sweetwater sell Eurorack gear, when there's a pile of manufacturers vying for business, open source is a BAD idea. If Mutable's module designs weren't as amazing as they are, Olivier Gillet wouldn't have this problem. But those amazing designs are a double-edged sword if they're not carefully managed like other important intellectual properties. Open source is applaudable...unless the concept boomerangs back around to kick your own ass, then it's very much a royal pain! This isn't like other firms just wholesale ripping off other firms' designs; there's a tacit "approval" for these designs to be used by third parties. But I think some better foresight about modular synthesis's exploding desirability might've been useful here.

You make a valid point, thanks for sharing your thoughts on that subject.

I'm still working on this rack. Tried some other configurations.

Compared to the previous concept I removed the stillson hammer, the pamela NEW workout and the fourbricks rook and replaced them with the Eloquencer. It's less performance/hands on oriented but has 8 cv outs and plenty of features.

I also got rid of the two 4xVCA and the panmix to replace it with the wmd permormance due to come out this year I believe. One thing I'm not sure of if this can replace the VCA's I had. My thinking is that the WMD performance mixer has CV control over level and pan over 8 channel . So it can act as a proper VCA I asssume?

The two Pico Drums were replaced by 2 x 2HP play.
With the space I won I also put back in the Maths.

One thing I'm not sure of if I should keep it is the comparator. I still fail to see how I can use it. I understand the way it works (generating a gate or a trigger as a result of comparing two signals) but cannot think of any practical uses I might have with it. So far I didn't find a demo online making use of a comparator in patch.

Any suggestions or ideas about this build?

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