So I have a Rosie in my Case, really nice that I can fade in between oscillators and effects but I also know that I can use an external mixer for the same thing, patching directly out of a VCA is also a thing and it would help free up some HP to add some more utility: S&H, Envelope Follower, maybe even some more VCAs.

I was thinking of replacing the Rosie with a Cold Mac, I love the Mannequins line of modules and really think that having Cold Mac along with some LFOs and other VCAs would be really fun for slowly blending sounds in and out of the patch. Would love some critique on the decision.

no boollie pls ModularGrid Rack

External mixers:
The are less expensive than mixer modules.
They offer more features.
They don't eat up HP space.

Internal mixers:
Operate at synth level.
Can offer CV controllable features like pan, volume, etc.
Fit conveniently in your case.

If you're using an external mixer, you output synth levels from your case into line level inputs. Some mixers can handle it... others can't. You may need some sort of synth-to-line-level converters. If you pass an output from the mixer back to Eurorack, the volume levels will be a lot lower and you'll have to boost the signal somewhere (which can introduce problems with noise-floor, etc.). If you want to use a Eurorack effects unit from an external mixer's aux output... you'll see what I mean.

Eurorack mixers are bloody expensive with only a handful of channels and they take up a lot of HP. If you're lucky they might have EQ and maybe one or two aux sends but usually not.

So it comes down to needs, knowledge, and budget. Each approach offers pros and cons and there really isn't a "best practice" model out there. You just have to pick your poison.

Hmm... about reducing the level of the synth to line level. This is something that the VCA could do, right? I would think that if the level begins to exceed what, say directly to a speaker without the mixer between them, it would begin to clip and distort the signal and stress the material of the speaker. Do you mean that if it were to REALLY exceed line level it might cause me to smell burnt circuits?

Should I test it out just to be sure: both directly to the speaker and also through the mixer? Could I monitor the level on the mixer's VU meter?

A VCA can be used to attenuate the signal. But that's just one signal. With a mixer, I assume you will have multiple channels of Eurorack level audio. So you'd need an attenuator for each signal. Six signals would mean six attenuators. If you're using a VCA for each, that's six VCAs. Which is expensive for just simple passive attenuation. Your mixer may have enough headroom without it and then you can turn down the input trim if possible. It really depends on the design of your mixer.

I wouldn't plug Eurorack levels directly to a powered speaker. You might end up blowing it up with high levels overloading or high levels of DC current being powered through the amps if the speaker isn't guarded against DC.

You can always conservatively try out the inputs by using an attenuator pot'ed all the way down then bringing up the levels while carefully listening and watching the meters on the mixer. But I wouldn't do something like taking the raw output of an oscillator and plugging it into the mixer.

hmm... You made me consider a slight edit to the rack. I think I might add a Doepfer A-183-1 for passive attenuation of the synth into my mixer from which I can monitor from. If I don't monitor the levels from the mixer I would have a Rosie that I don't really get much out of. I could now just use a Quad VCA for mingling the Eurorack levels and then output them to the attenuators.

It would still eat up a ton of my VCAs but I also have better control of their level this way. I'm sure that would work for putting them into a mixer now, right?

Passing DC to your amp and speakers: this video should explain very quickly why you don't want that to happen. Ever.

My suggestion to all of this is to actually use a...yep...Eurorack stereo mixer with proper VCAs, CV control over panning, AUX send/returns, and so forth. Yes, they cost money and yes, they take up space. But they're the right choice inasmuch as, in this build, they're the right tool for the job. If the idea here is to control the shifting from sound to sound in an even manner via modulation, sure, you could kludge together a bunch of VCAs and attenuators and so forth. Or just do this, plus an isolating output module to both attenuate the synth-level stereo feed and to provide isolation to keep from passing DC, prevent ground loop and noise issues, etc.

Let's look at this...right now, you have a Rosie as a "mixer" (it technically isn''s a crossfader with a cue line and headphone amp) and you're considering using the Quad VCA and two A-183-1s as VCA + attenuation (which, I note, does ZERO for DC issues and noise/ground loops between your mixer and the modular). This, totalled in hp, is 30 hp altogether. And in monetary terms, all of those are $408.

Without chucking the Quad VCA (you need that!), let's see what we can do. My suggestion would be to look at the Qu-bit Mixology, which is one of the cheaper and smaller full-CV stereo output mixers at 28 hp and $399. This gives you full CV over levels, AUX sends, and panning over four channels, plus stereo AUX return, metering, mute and solo switches. Adding a suitable and well-featured stereo output for this leads to Bastl's Ciao!, which offers balanced TRS 1/4" outputs, two stereo input pairs (the second can be used for a second signal chain, or for paralleling another stereo effect), headphone amp, clip indicators, and so on in 5 hp at $122(ish). So, $113 higher in price but MUCH more extensive in terms of features. And only 3 hp bigger in terms of "footprint". Frankly, the price and size difference vs. benefit...for me, at least...would point me more in the direction of the Mixology/Ciao! pair. It does everything necessary for not much more in about the same space.

That's a bit concerning. Considering the fact that I would have to remove some other modules to make room for a built in mixer like from WMD or Qu-bit. I like the idea of Bastl's Ciao! being the EOC module to make sure the signals that pass through are set for other devices to handle: appropriate level and appropriate signal type.

I like the idea of Qu-bit's mixer since the externel one I have can be used to EQ it along with my other peripherals and instruments. Speaking of, I do have a skiff from before. I use it for controllers, like Pittsburgh Modular's KB-1 and pressure points for a more hands on touch to they system, but, admittedly, I rarely use since I just prefer to clock Maths and Just Friends and allow the patch to run off of them.
I wouldn't have an issue replacing those controllers with these mixing tools, and I help keep the 9U case as is while also freeing up space for some more modules in it. Would that be a good plan to start?

If you really want to do outboard mixing, you don't necessarily need a whole lot of VCAs as was being suggested here.. that'd be a horrendous waste of useful VCAs in your limited rack IMO. Especially when you can just use passive attenuators to turn the levels down from your 10V modular to ~1V mixer levels.

Look into getting some attenuator adaptor cables like this:
The attenuator is built into the cable so you don't have to use any rack space to go from your modules straight to the mixer.

Or if you don't want a bunch of dongles, then you can use a module like the Levit8 that would have many attenuators packed in a small space. There are quite a lot of options for you to consider.

I do all my mixing in-rack, however, as I like how streamlined that is. But this is also the most expensive possible option.

Hello VolatileReaction and Lugia,

Lugia, why you didn't show me straight away that video about DC level blowing a speaker? ;-) Ha, ha, very clear demonstration.

By the way, why not using Doepfer A-138o & A-138p, that's only 20 HP, also 4 channel mixer, extendable with yet another 4 channels (or even more if you like), it has Aux & Panning too however it's less than half the money and you save a bit rackspace too?

VolatileReaction, I went through that DC part of output signals too, see the discussion at the Modular Discussions section and the thread ACL & Waldorf modules, then scroll below till after about two-third of the discussion, where I started to worry about DC signals, there also Lugia and Wiggler55550 provided useful information about this matter.

If you want to save rackspace, why don't start with Doepfer A-138o & p set, it saves you 8 HP (so that's one module for something else! :-) ) and it's less than half of the price of the Mixology. If you need more channels in the future and if you have more rackspace in the future then you can add one or more A-138p modules to increase the number of channels since that module setup is chainable (one A-138p module has 4 channels).

Good luck with your rack planning, it looks very interesting too me!

Thanks for all the feedback. I'd always see small output modules on the edges of most cases ad found them a bit lacking. I like the idea of using a mixer to properly EQ and blend signals together, it's why I liked the cross fader from the Rosie. Now, I'd like something a bit more involved with the rest of the case that instead allows me to push a few signals out while also letting me to route effects, filters, and modulation.

Thanks for all the suggestions; definitely have something to think over now.

Output modules are yet another set of collective victims of "Sexy Module Syndrome". Frankly, they're just not sexy, as a rule. But they're pretty essential, IMHO. It's convenient to have your level step-down inside your cab, for one thing. And if the module has ganged attenuation for stereo level control...well, bonus! But the critical thing with these is to find ones that have isolation and/or balancing transformers. For one thing, these help you avoid ground loop hum and "dirty" power noise. But also, transformer isolation is a sure-fire avoidance for passing DC through your audio output...because transformers don't pass DC, period. And as an extra benefit, you can overdrive and saturate output transformers to add a little warm crunchiness to your sound.

Like anything else that doesn't fit into Sexy Module Syndrome...they're not sexy, but that doesn't mean they're useless!