PSU3-Case build questions


#1

What is your opinion on buying a mains inlet with filter for a PSU3 based Case?
Is it a waste of money or worth it?

On wiki i also read (google translated) “When a grounded device (such as a computer) is connected to a non-grounded device, such as a hi-fi amplifier, through an unbalanced signal connection, the Y-capacitors, the grounding line of the signal cable, and the ground of the computer often extend across the sub-distribution transformer reaching humming loop, which can be heard clearly.”

Hope the translation makes quite sense. To me it sounds there can be also some disadvantages, but wouldn’t that be the case anyway, with or without filter?

Btw: would it make sense to choose an inlet with currant rating lower than 10A?


#2

the first question is: do you have noise/hum problems with your modular?
if you do, there is several things you can try before buying a mains inlet filter.
The PSU3 should be grounded to protective earth or am I wrong about that?

Btw: would it make sense to choose an inlet with currant rating lower than 10A?

do you mean an inlet on your wall that is rated for less than 10A? Why would that make a difference?


#3

The case is not built yet. I am collecting the last parts to go building it (and let a pro wire it).
The reason i came up with this in the first place is because i read somewhere else that someone should save money for this and that and get a filter inlet instead.

For grounding issues i added a soldering tag to my shopping cart as the psu3 wiring plan suggested (http://www.doepfer.de/a100_man/A100PSU3_wiring.pdf).

Until now i used a DIY-Kit#1 Case and never had any real problems, except some humming when i put the external transformer too close, but i did not ground it (to the rails or so) because the manual said only to to so in an non wooden case. I though read that i should, i don’t wanna highjack my own thread, but i guess wiring the internal supply-PCB to the rails would be the right thing to do?

10A current rating: I mean the inlet i put right into the case’s wall, plus i wouldn’t know, that’s the reason i asked.

So i guess i should order just as the wiring plan suggests, some inlet that can hold a 250V fuse (800mA) and has a switch (which i prefer of course) and not bother with a 30€ filter.


#4

I have absolutely no idea if a filter will do anything or not, so I cannot help you with that. I did some thorough research into the “noise problems” matter some time ago and have a relatively good idea where most noise problems with modular systems come from, but it’s a very complicated matter.
Usually the main problem is with bad PSUs and badly designed modules. Switching PSUs are the worst when it comes to noise, linear would be best and hybrid ones (like the PSU3) usually are somewhere in the middle ground.
A client of mine wrote this very informative introduction to power distribution, which of course related to them developing their own busboard system, but which I find a great read since it’s both easy to read and kind of exhaustive on the matter.
I also went through most of Graham Hinton’s post on MW and have worked with Genus Modu, who recently released this: http://genusmodu.com/products/libb.html
I’ll paste my reply from a thread on llllllll.co about noise problems, maybe it can be useful:

Not an EE either, but I’ve gotten a bit into “noise paranoia” recently and have started to check all my modules and the PSU for noise… just to find out that yes my PSU (TipTop Zeus) does produce a bit of noise, but it’s so low I can totally ignore it. Still I had some big problems in the past and I wish I had known some things I now know back then. So here’s a quick list that might help you:

  • usually the noise comes from the PSU (except if it’s EM-related) and propagates on the 0V bus (confusingly often called “ground”).
  • if you have noise problems 99% of the time it’s due to having a switching PSU, so if you can, get a linear one, or at least a good hybrid one.
  • if your PSU does not connect to protective earth (the third pin of your wall wart) it might also worsen things in certain situations.
  • ground lifts sometimes work, sometimes not. If you’re just using the modular at home/in the studio that might be doing the trick, but if you need to use the modular in different places, better solve the problem from the ground up.
  • first of all there’s modules that inject noise into the system, and there’s modules that are prone to receiving noise. So I would also ask: did you try to put the modules into the case one by one to see which ones were causing the problems? Sometimes this is a matter of having a wrong circuit design, sometimes it’s an inherent thing to the circuit. For example: overdrives, waveshapers, preamps and VCA that go beyond unity gain will apmplify the noise in the circuit. So if these produce the noise, you need to find out where it comes from, because it’s not a problem of the module’s circuit being done wrong.

Also, about “noise filtering busboards”: I’ve done some research into the matter and to me it seems there is no conclusive proof that these actuallty do much more than cost money. What seems to work is to have a busboard system with a very low-resistance 0V bus. I.e. things like Hinton’s busbars or busboards with thicker copper layers, but that will be expensive.


#5

Thanks for the content.

I also read about the libb on MW a while ago but i went with Doepfer bus boards since i got three boards for the price of one libb. And the oversea customs stuff means hassle to me. The last bit of your pasted comment also refers to the libb, right? I just thought about returning my A-100 Boards and get the libb because i saw i’d only need two of them instead of three (16 instead of 14 headers), meaning i could afford them if it’s well worth it. But i’m confused, and it sounds like it’s not.

So if it’s either robbing a bank and choose Hinton or sticking to the Doepfer route I assume the PSU3 (plus Doepfer bus boards) will be enough upgrade compared to my actual DIY-Kit-PSU and since i have limited budget i think it’s better to spend it on a good audio interface (sold my x32-rack and am left with a defective mackie onyx and a cinch 30€ behringer one :frowning:),


#6

No the quote above was a reply to a person who was having noise issues with his system, and I was trying to point him at possible causes.
Just to be clear: I’m not trying to sell you a LIBB, and I don’t get any share on the LIBBs that get sold.
I am running my system from 3 TipTop Studiobus Zeus powered busboards and am totally fine with that. I do have a bit of noise, but that is so low that I need to crank up the monitors at max to hear it, so basically my system is pretty decent noise-wise.
There’s only 1 situation where the noise can get a bit noticeable and that’s when I do record the modular in multiple takes. With each take the noise gets louder and when you start having 10 tracks you start to hear the noise on very silent passages.
I think you’ll very likely be fine with just the stock busboards and the PSU3, or at least I’d wait for them to arrive, put all the modules in see how it works/sounds before spending money for a solution to a problem you might not even have.
Once you have your system, do one thing: put in a mixer or mixing VCA (possibly a Mutable, so you can rule out sloppy circuit design), keep all the volumes at zero and connect the output to a mixer/PA. Then listen, or record it into your DAW. If you can hear noise at normal monitoring levels, then there’s something wrong. If you can’t hear anything you’re probably good.
You can still have noise problems later on if for example you use: preamp modules, waveshapers, distortions, or any other high-gain circuit which might amplify the noise, that is apparently normal and not due to bad design. Some modules tend to inject noise into the system and some tend to pick it up (in both cases it’s due to bad circuit design, but these things are more common in eurorack then you might think).


#7

If you are building the case yourself why don’t you just go for a meanwell and some diy busboards?


#8

@Papernoise: Don’t worry, i’m not feeling pushed either side and appreciate your input.

@shiftr: Because i have no clue. If you think there are easy alternatives feel free to point me at it. I can still return my PSU3. I read a lot about bad power supplys (*) and the trouble they can cause, so i thought getting the PSU3 is a good compromise between wrapping my mind around how to wire a PSU and solid quality.

(*) Don’t get me wrong, i “know” MW is far from manufacturing bad power solutions and since i spotted MW being on the PSU3 too i thought this would be fair enough.


#9

OK… The PSU3 uses linear regulators after a switching power supply. The meanwell is a switching power supply. There is debate about linear vs switching power supply’s. The meanwell is so much used in eurorack that i don’t think you’d run into any trouble. But of course there might be this one peculiar module out there that doesn’t like it.
The main point is the huge price difference. https://nl.mouser.com/ProductDetail/MEAN-WELL/RT-65B?qs=l0g2inPJSHND8ryGZwADcw%3D%3D
You’re not going wrong with a PSU3. The wiring job for the meanwell and the PSU3 is just the same.

I don’t think you need a filter on your AC power inlet. Those thing are mostly designed for the other way around. That is to prevent the mains net to get contaminated from spikes by equipment. Unless you 're planning on using some some strong electromotors in your case i don’t think it will be a problem.

With a normally good PSU you shouldn’t notice anything from your mains net.

Mains filter also won’t help with hum problems. That usually has to to with proper grounding and shielding and sometime with ground loops.

It all depends on how much you are willing to spend ofcourse and what quality you are looking for.


#10

I have to differ on this point. The Meanwell is used a lot in eurorack because it’s cheap not because it’s the best solution. Many people have run into problems with it. It’s certainly not the best option out there, actually it’s probably one of the worst (not the worst of course, there’s still the µZeus and some others :slight_smile: ). I had my good share of issues with it in the past.
In an ideal world, if you don’t have any high-gain circuits in your modular you could as well go with a Meanwell, since the noise floor isn’t that high you’d ever notice. But the problem is that modulars are very complex systems and many modules are not really designed properly, so there’s many factors that might amplify that noise. Buttom line is: less noise you have to start with, the better!

I had 3 cases with Meanwell PSUs. They are a solid powering option if you’re really on a budget and actually are better than many other switchers. You can tame the noise a bit by properly wiring it to protective earth (as explained by Graham Hinton on MW… you basically just do some redundant wiring from the busboard and PSU directly to the protective earth pin on the inlet and use a thick low-resistance wire).

Chek this thread here for more info: https://www.muffwiggler.com/forum/viewtopic.php?t=131748&highlight=&sid=357f8820fff159b9c37e3808cfa4ce54

If you really want to make a carefully pondered choice then maybe learn a bit about power and how that works, a good place to start is maybe this:
https://rabidelephant.com/pages/power
It gives you a relatively through introduction to the matter written in a not too technical way. I did understand a lot of things thanks to it.
This said, if you really want a Meanwell I have a used one for sale, but I wouldn’t recommend it.


#11

Also you might want to check this:


#12

That is a useful list!

It’s good to have different opinions!. I’ll add that my experience and opinion mostly is based on working with eurorack on a budget. I’ve collected quite a big eurorack system past 4 years which is almost completely DIY expect for some Mutable Instrument prototypes.
I wouldn’t be in eurorack if i wasn’t doing it on a budget. I’ve got 2 6U and 1 9U cases now which i’ve all build myself for less than €100 per case.
If you are buying a case of €500 euro and spending €3000 on modules to fill it i makes much more sense to spend some more money on a PSU.


#13

I think the PSU question is mostly one that relates to “bad case scenarios” and to how likely these are to happen.
One of the most frustrating things is switching on your modular with the intention to have a good time making a patch and then having to spend those 2 hours (or whatever it is) troubleshooting a problem which prevents you from enjoying the experience.
A cheap switching PSU might make this more likely, but of course it might as well never happen at all.

that’s how I started out as well, so I can relate to that very well. My first cases were filled with DIY modules (some of them I had put together in doubtful ways), my first busboards were just a piece of stripboard with connectors soldered on and my PSU was a Meanwell RT-60B. I did probably borderline on electrocuting myself a couple of times. Looking back it was both foolish and a waste of money. I sure have learned something from it, but it could have gone wrong in many ways.
One big error I have done back then is to listen to people telling me what I should do, without questioning their suggestions and without reading up how things work. So one big suggestion I want to make: don’t assume anything we say here is true. There’s people out there who know what they talk about, Graham Hinton knows what he’s talking about, Phil from Rabid Elephant sure did his homework and there’s many other people out there. But you also probably best take everything the experts say with a grain of salt and please don’t just do something that somebody on a forum – who you don’t know much about – suggested.

If I’d go back I’d just get a Doepfer 6U case and be done with it, would have cost me less, put my life less in danger and I’d probably still have it, though I also have a Meanwell-powered case which does work decently after doing some proper ground wiring.


#14

The article on rabidelephant is a great read, thanks.

I wanted to create a thread here to ask for advice from the start and before buying anything, but somehow i didn’t.

I also considered to just go with a LC9 in the first place, but i didn’t like the rails being lower than the sides of the case and that i couldn’t lay it down on its back because of the mains in. So i decided to build something similar on my own.

Another reason to build it myself is that i love to learn a lot from doing it. Years ago i wouldn’t know what to do when my bicycle light breaks, now modular taught me.

Concerning the low-resictance thick wire for grounding: I would go with this, 1.5mm litz wire, if i wouldn’t have read about it better be low resistant and thick. But this is, right? Would you (or Graham Hinton) possibly mean something completely different?

Once again thank you for your input, much appreciated.


#15

You can ask him directly on MW (if you’re registered there). IIRC solid core wire would be even better. No idea what the resistance of this type of wire is, I don’t see any info on Reichelt.
I’m sure Hinton meant some specific type of wire, which I was never able to find though.
In my previous case building attempts I used more or less the same wire you linked, though that does not mean it’s the right thing to do :slight_smile: