Petite sampling rack advice?

Hello,

I'm looking to build my first rack, mainly for sample manipulation and integration with VCV Rack. The ER-301 would be the main sound source along with the Nebulae. The Catalyst looks fun for Octatrack-style crossfading between parameters. I have a Pyramid and Bitwig for sequencing and additional modulation, and a MIDI controller via the FH-2 for more knobs.

Any glaring omissions or missteps? More subtle problems? I know more VCAs is kind of a mantra, but I'm hoping that the ER-301, VCV Rack, and even Disting could fill that role - along with filters and everything else - while I'm getting my feet wet.

My main concern is power: I have the Pittsburgh Lifeforms Research Console, which has 1 Amp +12V, -12V, and +5V. The MG planner shows a power consumption of 1140 mA +12V / 183 mA -12V, but the Nebulae can run on 5V, which brings it down to 822 mA +12V / 176 mA -12V. Am I calculating that correctly and being conservative enough?

I'm not entirely sure I know what I'm doing, but am reading up, trying the put together something modest with lots of learning potential, and hoping not to electrocute myself. Any advice would be greatly appreciated.

Thank you,

Tyson

https://www.modulargrid.net/e/modules__racks/data_sheet/1042792

Rule #1: never assume that the MG amperage figures are correct. ALWAYS overestimate your current needs.

Rule #2: Since there's a spike in current draws when you turn a device on, even if your operating current is 822 mA, that doesn't mean your inrush current is also 822 mA. And it only takes a fraction of a second for certain components in an overtaxed power supply to go "pop!".

Rule #3: When speccing power supply current figures, take your MG module amperage sum, then add 1/3rd as much more to that figure. Then add more besides that. You DO NOT want to push a power supply; instead, you want that power supply to loaf along like its not got much to do. This adds up as lower operating temps in the case, more stability across the system, and less component stress.

So, given the 1140 mA figure (I don't recommend using 5V unless necessary...keep things simple), you really need something with about 1.5A to get bulletproof operation. 1A with that = BOOM! or something similarly unpleasant along those lines. And if you do go the 5V route, you're still not 100% guaranteed that that'll work...1.25A for 822 mA is more sensible.

EDITED Nov 14th 2019, 00:21

Hi Lugia,

Thanks for your detailed reply. Unfortunately, it's not what I wanted to hear, so I demand a retraction. How dare you lecture me about some made up "rules" after I put my heart and soul into that theoretical rack?

No, seriously, thank you. Is there a downside to powering the Nebulae with 5V other than needing to keep a separate tally of the power usage? According the the ER-301's website, its peak current is 250 12V+ rather than the 300 listed on MG, which would bring the 12V+ total down to 772. I understand that the consumption listings in MG shouldn't be taken as gospel, but it seems I'm painfully close to being able to safely power this little rack with the supplied power. And I admit, just aesthetically, I'd rather not have two separate "on" switches, even if - especially if - one isn't being used.

But I'm prepared to hear what I don't want to hear.

Thank you,

Tyson

Did some checking, and the VRL cab's 5V line has 1A available. My concern was that the Nebulae v2 would draw too much for that, but Qu-bit's own data shows it as having a draw of 47 mA on +12, 7 mA on -12, and 271 mA on the 5V bus. If you can get your +12V bus draw down to 700 mA-ish, you should be in the right current ballpark. But again, check the manufacturer websites for the data here, since everything's getting close to those P/S limits.

The other thing I'd consider changing would be the mixer. A better choice would actually be the Happy Nerding 3x Stereo Mixer, I think...while it draws more than the JPSynth one and has one less stereo input, it's also 2 hp smaller and because it has an onboard TRS out that can be used for headphones, it eliminates the need for the HPO, and that opens up another 2 hp. The Nebulae should then fit into the space occupied by the Catalyst (move that to the other row), and this puts your free 4 hp in the other row for use by another module.

EDITED Nov 14th 2019, 23:19

Hi Lugia,

Thanks for your detailed reply. Unfortunately, it's not what I wanted to hear, so I demand a retraction. How dare you lecture me about some made up "rules" after I put my heart and soul into that theoretical rack?

No, seriously, thank you. Is there a downside to powering the Nebulae with 5V other than needing to keep a separate tally of the power usage? According the the ER-301's website, its peak current is 250 12V+ rather than the 300 listed on MG, which would bring the 12V+ total down to 772. I understand that the consumption listings in MG shouldn't be taken as gospel, but it seems I'm painfully close to being able to safely power this little rack with the supplied power. And I admit, just aesthetically, I'd rather not have two separate "on" switches, even if - especially if - one isn't being used.

But I'm prepared to hear what I don't want to hear.

Thank you,

Tyson

-- tyson

Hi Tyson,

I'm going to include some info that's loosely related to your posts and some that's more on target.

Some modules offer alternative powering solutions and set-ups. For example, modules with vacuum tubes in them may require additional power supplies because of the huge draw from tubes at start-up. Erica has a vacuum tube series that requires a separate "tube warmer" power supply for start-up. I believe they may have solved the issue for later models in the series. But if you see a tube in your gear... you really want to focus on start-up voltage draws. What Lugia said is important.

Digital modules are noisy. It's just a fact of life; especially with modules with display screens. Digital modules are also built to different specifications depending on the builder. You might find people putting digital modules in a separate case or in a corner of their case away from modules that might be more sensitive. Some modules, like those from Noise Engineering, have a toggle switch on the back that allows them to be powered from the 5v bus in order to improve interference.

If you hear the term "passive" it means the module requires no power. A passive mult or a simple attenuator would be examples. Some will work passively, but have "active" portions. The Noise Engineering "Mutis Jovis" is passive four channel mute module, for example. It works passively. But if you plug it in, the LEDs indicating signal level will work.

Hope the information is helpful in some part.

EDITED Nov 15th 2019, 21:08

Hi Lugia and Ronin,

Thanks for your help and for all the information. I looked at replacing the 8 HP mixer with the Happy Nerding 6 HP one, but there still wasn't quite enough room for the Nebulae on the bottom. I was racking my brain, so to speak, and had a very unoriginal idea: adding more space. With a third, separate rack in front (Pittsburgh Cell DC with +12V 900mA), I'd have plenty of power for the ER-301 and the Catalyst, and could also play it separately from the rest of the rack: on the couch or at a cafe, or possibly even on a couch at a cafe.

With the top two rows, I added the Magneto and two Xaoc modules. The total +12V consumption for those two rows, (with the Nebulae on 5V) is 727mA, which seems to be sufficiently safe.

But is it too safe? I mean, from a sampling/sound design perspective? I realize this is much more subjective territory, but the Magneto is taking up a lot of real estate, relatively. And while I love the look of the two Xaoc modules together, and the potential for slow and evolving modulation, maybe I could replace one of them with something more wild and/or crazy? As for digital vs. analog modules, this rack seems to be on the extreme digital end, which I don't mind if it's not distractingly noisy.

I had planned on just getting the ER-301 and the ES-8 to play around with Mutable stuff on VCV Rack, but now I'm in full modular avarice mode. Realistically, there are going to be gaps on the rack while I try to make up my mind and get good deals. The ER-301 is the one module I'm married to, and which will hopefully arrive next month. The Catalyst and Expert Sleepers stuff has been ordered. The rest, except for the headphone out, is still mostly up in the air.

Thanks again for your help.

Tyson

https://www.modulargrid.net/e/modules__racks/data_sheet/1052041

EDITED Nov 17th 2019, 00:41

For what you are planning, the lack of filters, VCAs, VCFs, attenuators and attenuverters, you are just going to have a very expensive and poorly functioning sampler on your desk.

You've fallen into the same pit as most people new to Eurorack fall into. You seem to not understand HOW a control voltage environment works and you're cherry picking modules that you seem to like. You really need to educate yourself how Eurorack/modular synthesis works and start planning AFTER.

I realize that you're planning for this to work with VCV Rack. But there are gaping holes here. I'm not picking on you. I hope everything works out well and you get everything out of your gear you're looking for. But this build is just lacking.