Mean Well PSU

Hi all, I’m building another eurorack case (6U 104hp) that will mostly be filled with MI modules. I used a Mean Well RTB50 PSU with with my last case and considered buying an RT65 for this new build, however, I’ve been advised against it on a FB group…I wish to ask what you guys think, is the Mean Well noisy, not safe, generally not good for eurorack?

Thanks In Advance

Adam

I’m running a 180hp, 4 row case on three meanwell supplies (one for each rail) an I never had problems with noise or interference.
I think it largely depends on your wiring - use thick wires and wire everthing up with a central GND star point.
Also it very much depends on the modules you want to use. Some are poorly designed and pick up noise easily. Not a problem with MI modules, but maybe you want to later use other brands, too?

I think for 6U, 104hp, that -12V rail may be underpowered at just 500mA. Why not use three separate meanwells (one for each rail)?

A while ago I quickly drew this up for someone in a Synth DIY group on facebook:

Thank you very much :slight_smile: The diagram will be very helpful! 6U is only two rows and will house about 14 modules…I will get the RT65B…Slighty off topic, I bought a distribution board from a guy on here I think it was (Frank, fcd72?) is he still frequenting these parts as I’d quite like another one as it was perfect for the job :smile:

You can very simply build one yourself with stripboard. The traces are correct already, so you simply have to sodler the headers to the stripboard and you’re ready to go.
I would, however, recommend to thicken up the traces with some solid wire. Just solder the wire directly onto the traces of the stripboard.

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That is a brilliant idea! Thanks

There’s basically two big disadvatages of the open-frame Meanwell PSUs: one is that you have a direct connection from inside the case to 220V (or 110V), not a problem if you know what you’re doing, but maybe something that is sometimes a bit underestimated (as in, you might expose yourself to electrocution if you don’t do things properly). The other downside is noise and ripple. This is a much more complicated subject and a lot of people will tell you very different things about it.
My personal opinion and experience is that in most cases you can get away with a Meanwell if you stay clear from badly designed modules (but how do you know a module is badly designed? There’s some very popular brands, which have some rather badly designed modules) and wire things up properly. There’s also some types of circuits which can raise the noise floor: compressors, VCAs that amplify beyond unity gain, distortion, wavefolders, mic preamps etc. In some cases you might hear the noise more, in others less (eg. a distortion is might be less probablematic).
There’s also different types of noise. I have 3 different cases here: one that runs from a Meanwell RT-65B, one with 3 TipTop Zeus boards (not uZeus). The Meanwell makes a pretty characteristic high-pitched whine, the TipTop sounds more like analogue white noise.
I did check the peak values of the noise I have in the system (not a scientific test, just something to see how much noise I had) and the Meanwell was around -70dB, while the TipTop was around -80dB. 2 different systems with different modules, so I take these figures with a pinch of salt. Fact is, if I record 10 tracks from the Meanwell I get to hear the noise really well, it’s more audible also because of the spectrum. The one from the TipTop gets masked much more easily by the actual music I’m making.
Would I buy another Meanwell, probably not? Does it work, yes, but you need to be aware of the limitations. It’s certainly not the best solution, it’s also not the worst, likely in the lower spectrum quality-wise, but it’s cheap and easily available.

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Interesting. I never experienced a high pitched noise with my rack. What module did you “listen to” when you observed this?
I had my system playing really loud in a dance club and didn’t notice anything.

Sidenotes...

I have lots of MI modules but also the guinguin MME (minimoog clone) and various other “analog” (potentially not properly designed) modules. I’m using my own output module (really just two opamp stages with some mixing in between) and I enter my Behringer XAir mixer with an unbalanced signal at modular levels (pad enabled in the mixer).

Thanks for all the input guys. I think I will go for the meanwell, or if work goes well may push the boat out and get the Doepfer PSU3…that seems to be a decent PSU by all accounts!

With the Meanwell, just make sure that each rail is loaded to the specified amount. If it isn’t, you will get significant ripple and noise in the audible spectrum. But with adequate load on each and every rail, I have found them to be remarkably quiet. First-gen Braids modules which require 5V are a great way of loading up the 5V rail, btw.

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The Doepfer PSU3 uses Meanwell power supplies (then linear regulator)

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Okay thanks…I’ve made my mind up, I’m getting the meanwell :smiley:

The quick&dirty test was done with a 3U system with a mix of modules (mostly Mutable and Hexinverter). I used the Colour Palette and I think Shades to check the noise floor. My test usually works like this: use a VCA or mixer with nothing plugged in, I connect its output to my computer’s audio interface (Presonux Firebox). I set the modules’ output volume so that an oscillator plugged into it, plays at about -12dB in the DAW. Now see what the peakmeter says and maybe look at the spectrum using FFT.
My conclusions of these simple tests (which were just a way to see how well that combination of modules would work with that PSU) were more or less these:

  • while a patch is playing, even at louder levels, the noise is inaudible. It’s almost inaudible also with nothing playing, since at -70dB it’s really hard to hear anything except if you really crank up the volume. It should of course be noted that usually the system will not be silent, though of course ymmv, for eg. if you make really quiet music, or like me you use the modular to process field recordings this is a different thing, than if you make dance music with a relatively high and more or less consistent level.
  • I did use this system with different combinations of modules in several live situations and also never heard any noise.
  • I did start to have some minor problems only when recording several takes from the system into the DAW (or using a looper and overdubbing a lot), since with every layer the noise-floor gets louder and it can become quite loud if you do that a lot.

it should be noted that I did do some redundant wiring from the PSU and busboard to protective earth on the power inlet to prevent noise problems, and that did seem to work. Unfortunately I didn’t do some more proper testing, but years ago I had a lot of noise coming out of this system (but with different modules)… probably some module with bad circuit design, but I never really did troubleshoot that, and later I did change a lot of modules anyway. So to be honest, it’s just my speculation that the wiring has improved things, based on the fact that I did not hear any more noise after that.

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Great! Thank you for the detailed answer. Yes, I rarely made quiet music with this rack and I don’t do massive overdubbing, so thats probably why I didn’t notice anything.

What do you mean by that? Do you mean a star ground like in my image above? Or did you add additional wires in parallel to the existing ones? Because that can intruduce ground loops, but maybe inside the case it’s not as noticable over the positive effect of the (overall) thicker wires.

But, one thing I forgot to say earlier, a whine-y type of sound is probably normal for “pure” switching PSUs, and it does make the noise a bit easier to hear than something that is more like white noise (frequencies more evenly spread out over the whole spectrum).
But hey, it could be just mine, I certainly did not make a thorough, scientific test. But it would be interesting to hear what you can hear with yours.

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FWIW, I found that the level of the high-pitched noise went down when more power was drawn from the PSU.

I have 3 cases with meanwell PSU’s i never noticed any high pitched wine.
Maybe i’ll have to look for it better :slight_smile:

I can totally confirm that. If you have no modules at all plugged in it makes a lot of noise and the more current the system draws the less it gets… until you reach the upper limit I guess. I’ve never had enough modules (or modules that power-hungry) in the system to test that though.

I tested this when I first got an RT-60B. The audible whine, and the ripple on the supply rails, is quite bad until you load each rail to the specified minimum. Then , within 100mA of that minimum, the whine drops away, and so does the ripple. 100mA above the minimum and no whine is audible and the ripple is very small and above 60kHz. But you need to load each rail. Not just some of the rails. All complaints about whine and ripple from genuine Meanwell supplies stem from inadequate loading, I suspect.

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from what i understand it will happily load more than 500mA on the -12V rail.