I've been wanting to get into eurorack for a very long time. I own four semimodular synthesizers, a beatstep pro and sq1, and even bought a Behringer CP1 A months a go because i found it very cheap on eBay which I havent touched at all.

cheap is not often associated with good... the b-company power supply is almost definitely not powerful enough to power the 6u 104hp case you envisage - just checked and you've got 2 - might work... remember the semis will want power and you need to leave at least 25-30% headroom on each rail

My goal:
I want this rack to be focused only one thing, and thats glitchy percusive/drum sounds. I'm not interested in creating a basic 'kick snare hat' sort of drum machine since I already have a Digitakt and RD9 for more conventional drum sounds. What I really want is to be able to explore sound design but in a rythmic way, both in terms of sequencing and sound modulation.

so in my mind that would be oscillators, vcas, envelopes, lfos, filters and maybe an effect module or 2

I will list some of the artists that inspire me in order to give a clearer understanding of the sound I'm trying to achieve: Aphex Twin, Floating Points, Jean Jelinek, uZiq, Squarepusher, Venetian Snares, etc...

I already have a Neutron and DFAM, also I will be using my Beatstep pro as the main sequencer (which has a probability function and can kind of work as a basic 'generative' sequencer). I want to start with a 6U 104hp case in which I want to put both Neutron and DFAM and I'll just remoove them as I get more modules.

The rack I've planned:

I would have helped here and posted a link to the url of your actual rack... but I couldn't be bothered to sift through 8 racks to find the right one... jpgs are shite...

- I want to bring effects in and out at random times. Would Pamelas New Workout combined with Twiigs allow me to send random clocked gates to the mix inputs of the effects I've put in the rack?

I'd tend towards Pams Pro Workout as this will probably allow you to do this in a single module - and use envelopes not gates

  • One of the most important effects I wan to have is a beatrepeat which would allow me to modulate the lenght of the repeats triggered randomly at clocked intervals. Would Databender be able to do that? Are there any better alternatives?

worth looking at: clouds clone with the kammerl beat repeat firmware... you'll probably want attenuators for modulation

  • I have not included any VCAs, envelopes or utility modules, this is becuase the three voices I have in the rack already have built in VCAs and envelopes, plus the Neutron has two attenuators, slew limiter and a basic sample and hold. Am I missing something important here? This is the first time I build a eurorack synthesizer and I'm worried that I might not even know what I dont know.

are the vcas, envelopes and other fundamentally important utilities patchable and still usable in the semis? I doubt it... think again these are all fundamental sound design building blocks... you probably want a lot more of them, not less

  • Is it absolutely necessary to have an output module? I've seen a lot of people on youtube mixing eurorack signals with outboard mixers and not getting a lot of noise. My idea is to mix all the voices with the STMX module, then send the output into Databender as a final effect and then from Databender straight into my Mackie CR-1604 mixer. Would I be ok doing that?

it is not necessary to have an output module... but it really depends on whether or not whatever you are sending it to can cope with modular levels without clipping

s0, it will probably work.. but as @ferranadsr said I wouldn't want to go straight into an outboard mixer with the output of an effects module - a more fully featured mixer with a send/returmn facility would be a better idea...

I have watched all of Grant Boss's videos on youtube a million times, and pretty much I want to be able to do what he does but in a waaaaaaaay smaller case.

this is probably unrealistic... you may be able to achieve a small subset of what he does, but generally people have large cases for a reason... one of which is being able to run multiple voices and effects chains at once - which you won't really be able to do in a small case

"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia

Utility modules are the dull polish that makes the shiny modules actually shine!!!

sound sources < sound modifiers < modulation sources < utilities