Background electric noise problem

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anre
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Background electric noise problem

Post by anre » Fri Feb 14, 2020 11:36 am

Hi! I would like to address my question to anyone who had similar issue with the background noise like mine. You can hear it in my short video. I normalized audio, so it sounds exaggerated, and while I'm playing it is not audible under the sound of synths, however in quieter conditions the noise is pretty annoying. I suppose that in conditions of big sound on the stage this is really inappropriate and unacceptable, as well as for recording process. I wonder what can cause such type of noise and how I can prevent it. There are mother-32 and neutron in the case. When I tested the neutron in its native case it didn't produce such high pitched noise (I didn't test mother-32 though).

A little sad story:
There are other modules in the case, such as After Later Audio uBurst and Antumbra Atom (they produce more or less similar issue), all is mixed in Blue Latern Modules Sir MixALot. I bought the case pretty recently, it was assembled with its power supply. Once I started using it one sad thing has happened with it. There was one more module in it, however when I tested the neutron outside the case (took it out from case to set up with computer via usb) while the case was power on, a tip of the mini jack cable has touched the power bus in the case. Another tip was connected to a poor module powered in the case. It caused short circuit in the module and it died. I couldn't power it on anymore. So sad. Now you can see a piece of carton instead of it on the video.

I wonder if this accident could cause any damage in the filters of the power bus? or could it damage something in other modules (for example in MixALot) that normally filters out or reduces such noise? I can guess that the module received the entire strike and died, but it was patched to all other modules via its cv outputs, that's why I'm worried about them too.

It happened right after I started using the case and I can't compare how it sounded before and after. Although I have another power supply, but it doesn't sound clean as well with MixALot (relatively the same problem), however before the new case I used that power supply and didn't notice such noise.

I have no expertise in electronics to understand the nature of such noise and estimate possible consequences of the accident . Please help me if you have experience with something like this.

Thanks.


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Re: Background electric noise problem

Post by djs » Fri Feb 14, 2020 12:11 pm

What happens if you unplug the power for all modules from the case except for the mixalot? I mean, plug the mixalot into the audio output with nothing running into it? Does the noise still occur? If you add the modules back in one at a time, does one particular one bring in the noise?

Also, what's the power capability of the case?
"Noise is what the Earth is made of" - David Bowie

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Re: Background electric noise problem

Post by anre » Tue Feb 18, 2020 9:32 am

djs wrote:
Fri Feb 14, 2020 12:11 pm
What happens if you unplug the power for all modules from the case except for the mixalot? I mean, plug the mixalot into the audio output with nothing running into it? Does the noise still occur? If you add the modules back in one at a time, does one particular one bring in the noise?

Also, what's the power capability of the case?
I've done what you suggested to me. It turned out that I have 2 problems with noise: a parasite high pitched noise and noise produced when I'm touching the cables. I've made two videos for each. The first video contains my comments to let you undestand what I'm doing, on the second video I'm simpy touching the cable to cause the noise.



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Re: Background electric noise problem

Post by djs » Tue Feb 18, 2020 10:54 am

What happens if you move the mixalot to a different power bus board? Or change the inputs on the mixer to different channels for the mixalot and the mother 32? Can you recreate this noise without the mixer in the loop?
"Noise is what the Earth is made of" - David Bowie

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Re: Background electric noise problem

Post by loydb » Wed Feb 19, 2020 7:10 am

Watching...

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Re: Background electric noise problem

Post by Graham Hinton » Wed Feb 19, 2020 7:45 am

anre wrote:
Tue Feb 18, 2020 9:32 am
It turned out that I have 2 problems with noise: a parasite high pitched noise and noise produced when I'm touching the cables
The high pitched whine is 1kHz which is probably the switching frequency of your switched mode PSU. You get pickup when you touch the cables because the system is not grounded and so you have no screening.

You should be using a TS to TRS cable going to the mixer, but that won't solve the problem of your case.

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Re: Background electric noise problem

Post by anre » Wed Feb 19, 2020 1:09 pm

Graham Hinton wrote:
Wed Feb 19, 2020 7:45 am
The high pitched whine is 1kHz which is probably the switching frequency of your switched mode PSU. You get pickup when you touch the cables because the system is not grounded and so you have no screening.

You should be using a TS to TRS cable going to the mixer, but that won't solve the problem of your case.
Could you give me some advice about how this problem is traditionaly solved, please. How likely that it's been caused by that accident with the short circuit? I mean some damage in the PSU or in the modules that might have caused such abnormal behaviour, e.g. impaired filtering of the whine.

For the second issue. Is it possible to add ground to the case itself? Usually I play without an extrernal mixer, just with headphones connected to MixALot.

Thanks you. I appreciate any information about this.

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Re: Background electric noise problem

Post by Graham Hinton » Wed Feb 19, 2020 3:13 pm

anre wrote:
Wed Feb 19, 2020 1:09 pm
Could you give me some advice about how this problem is traditionaly solved, please.
The well established tradition is to replace the PSU and case. Sorry, I know that is not what you want to hear, but there are lots of second rate cases out there slapped together without considering the correct electrical requirements. If it doesn't have a 3 pin IEC mains inlet don't waste your time and money.
How likely that it's been caused by that accident with the short circuit? I mean some damage in the PSU or in the modules that might have caused such abnormal behaviour, e.g. impaired filtering of the whine.
Most PSUs have some protection on their outputs so that is unlikely, but not impossible. PSUs are expected to get shorted whereas modules are not.
For the second issue. Is it possible to add ground to the case itself?
Yes, if you know what you are doing. The problem is that there is unlikely to be any ground available so you need another connector on the case and most busboards don't provide a suitable connection point anyway.

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Re: Background electric noise problem

Post by anre » Thu Feb 20, 2020 7:41 am

Most PSUs have some protection on their outputs so that is unlikely, but not impossible. PSUs are expected to get shorted whereas modules are not.
I thought the same that there should have been some protection. However the module, which patch cable fell on the board, died. Does it mean that the board didn't have a proper protection agains short circuits? Can such things happen with other high quality PSU's? I've seen many times on the Internet how people are playing their partly filled modulars without any blank panels to cover the gaps where the patch cables may fall to and cause a terrible situatution like mine. Relying on them I didn't think that there was any risk to get the system shorted.

Image
Yes, if you know what you are doing. The problem is that there is unlikely to be any ground available so you need another connector on the case and most busboards don't provide a suitable connection point anyway.
The power brick does have 3 pin IEC mains inlet. I use a standard Mean Well GST60A15-P1J. However I don't know whether it passes grounding further to the outputs. It's what I'm curious about as well. On the inlets of the PSU there are 3 pins, but only 2 of them are used. Does that mean that those 2 are used for + and -, and that free one is supposed to be ground but not used for some reason?

Image

Image

The PSU I use is https://www.clank.eu/xpsu, and as far as I understand it's introduced as a safe, quiet and high quality power supply. P.S.: I am not trying to blame the PSU and its manufacturer. I'm quite a newbie, hopefully I do something wrong and there is a solution. Thanks.

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Re: Background electric noise problem

Post by Fog Door » Thu Feb 20, 2020 8:17 am

people are playing their partly filled modulars without any blank panels to cover the gaps
I do not know a thing about electrical matters, but just from a common sense point of view, that is not a good idea. Although depending upon the orientation of your case, the risk of something horrible happening will vary. Sorry to hear you've had the bad luck to learn that the hard way though.

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Re: Background electric noise problem

Post by cptnal » Thu Feb 20, 2020 9:47 am

Fog Door wrote:
Thu Feb 20, 2020 8:17 am
people are playing their partly filled modulars without any blank panels to cover the gaps
I do not know a thing about electrical matters, but just from a common sense point of view, that is not a good idea. Although depending upon the orientation of your case, the risk of something horrible happening will vary. Sorry to hear you've had the bad luck to learn that the hard way though.
Indeed. All it takes is one stray patch cable. :deadbanana:
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Re: Background electric noise problem

Post by anre » Thu Feb 20, 2020 10:10 am

I've contacted the manufacturer which I had ordered the case at and their engineer kindly replied to me that I'm using a wrong power brick. They recommend Mean Well GSM60A15-P1J, while I use Mean Well GST60A15-P1J. I did know that they recommend that "GSM" power brick for the power supply, but I already had the "GST" one by the moment the case was delivered to me. I didn't think that there is any significant difference between them. However they told me that there is only difference and it's in grounding. GSM is grounded to home ground, GST is floating. They are sure that this is the reason of the issue (at least of the one with pickups).

I've ordered the GSM power brick and when I perform testing with it I will post back about the results.

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Re: Background electric noise problem

Post by Blairio » Thu Feb 20, 2020 12:40 pm

cptnal wrote:
Thu Feb 20, 2020 9:47 am
Fog Door wrote:
Thu Feb 20, 2020 8:17 am
people are playing their partly filled modulars without any blank panels to cover the gaps
I do not know a thing about electrical matters, but just from a common sense point of view, that is not a good idea. Although depending upon the orientation of your case, the risk of something horrible happening will vary. Sorry to hear you've had the bad luck to learn that the hard way though.
Indeed. All it takes is one stray patch cable. :deadbanana:
I haven't had any noise problems that led me to getting rid of kit. I have however had heat problems resulting in oscillators with less than ideal temperature compensation being given the heave-ho. The odd ( or more accurately strategically placed blank space can help in this regard.

Yes, it may be possible to drop a cable through a blank, but remember the target for a cable is a 3.5mm hole. If we can't hit that target, we are in trouble

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Re: Background electric noise problem

Post by cptnal » Thu Feb 20, 2020 2:17 pm

Blairio wrote:
Thu Feb 20, 2020 12:40 pm
cptnal wrote:
Thu Feb 20, 2020 9:47 am
Fog Door wrote:
Thu Feb 20, 2020 8:17 am
people are playing their partly filled modulars without any blank panels to cover the gaps
I do not know a thing about electrical matters, but just from a common sense point of view, that is not a good idea. Although depending upon the orientation of your case, the risk of something horrible happening will vary. Sorry to hear you've had the bad luck to learn that the hard way though.
Indeed. All it takes is one stray patch cable. :deadbanana:
I haven't had any noise problems that led me to getting rid of kit. I have however had heat problems resulting in oscillators with less than ideal temperature compensation being given the heave-ho. The odd ( or more accurately strategically placed blank space can help in this regard.

Yes, it may be possible to drop a cable through a blank, but remember the target for a cable is a 3.5mm hole. If we can't hit that target, we are in trouble
Also true. But have you ever left a cable hanging for later use? Then there's the carnage that is unpatching! :woah:
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Re: Background electric noise problem

Post by Graham Hinton » Thu Feb 20, 2020 2:52 pm

anre wrote:
Thu Feb 20, 2020 7:41 am
Does it mean that the board didn't have a proper protection agains short circuits? Can such things happen with other high quality PSU's?
It's nothing to do with the PSU, it's a problem between that module and the busboard.
Modules are normally protected at the power inputs against incorrect connection, but you can't expect protection against patch cables being dropped at random places. Outputs are normally protected against shorts to 0V, but not necessarily to other voltages. You may have been unlucky and touched the -12V rail while the output was at +10V or similar.
I've seen many times on the Internet how people are playing their partly filled modulars without any blank panels to cover the gaps where the patch cables may fall to and cause a terrible situatution like mine. Relying on them I didn't think that there was any risk to get the system shorted.
You can win Russian Roulette many times, but you only lose once.
The power brick does have 3 pin IEC mains inlet. I use a standard Mean Well GST60A15-P1J. However I don't know whether it passes grounding further to the outputs. It's what I'm curious about as well. On the inlets of the PSU there are 3 pins, but only 2 of them are used. Does that mean that those 2 are used for + and -, and that free one is supposed to be ground but not used for some reason?
It's not + and - its Live and Neutral AC mains. If the ground pin is connected it is usually only for the internal chassis or "frame ground". Connecting the ground through to the outputs is no use because it is then sharing a current carrying long cable. You need a direct connection. When I said " If it doesn't have a 3 pin IEC mains inlet" I was referring to a case not an external brick. You will never get proper grounding using a brick.
Image
No, that is a break contact. The normal usage would be an internal battery in a pedal that is cut out by connecting an external wallwart.

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Re: Background electric noise problem

Post by anre » Thu Mar 05, 2020 6:51 am

Today the new power brick Mean Well gsm60a15p1j was delivered to me and finally I've done the testing. And fortunatelly the grounding noise, when I touch the cables, has disappeared. I am happy with this and express a lot of thanks to the manufacturer for the recommendations. It turned out that very similar models of power bricks may have significant differences when it comes to the grounding noise.

However, another type of noise, that is 1Khz produced when Atom Antumbra is powered to the same board, still exists. Therefore I have questions to owners of Atom Antumbra, if any of them are reading this post. Could you share your experience with this module? Do you have similar noise problem with it as I have with mine? And what solution have you found? I guess that other cheap modules may produce the same noise too, so this is addressed to them too.

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Re: Background electric noise problem

Post by Graham Hinton » Thu Mar 05, 2020 8:09 am

anre wrote:
Thu Mar 05, 2020 6:51 am
However, another type of noise, that is 1Khz produced when Atom Antumbra is powered to the same board, still exists.
Look up the spec of that module: +12V @ 130mA and -12V @ 10mA.
That tells you what you need to know. The difference of 120mA is flowing into your 0V and that will contain the 1kHz.

Three things have to be in place to have an interference problem: A source of interference, modules sensitive to interference, and a means of coupling them. Remove any one of those three and you don't have a problem.

Eurorack was never designed for modules like this, all the early modules had lower currents and the current differences were small so there were not large currents going in to the 0V. If you want to use digital modules and sensitive analogue modules in the same case you need a much lower resistance in the 0V distribution as that is the means of coupling. Lower than ribbon cables and pcbs can provide.

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Re: Background electric noise problem

Post by anre » Sat Mar 07, 2020 3:08 am

Graham Hinton wrote:
Thu Mar 05, 2020 8:09 am
anre wrote:
Thu Mar 05, 2020 6:51 am
However, another type of noise, that is 1Khz produced when Atom Antumbra is powered to the same board, still exists.
Look up the spec of that module: +12V @ 130mA and -12V @ 10mA.
That tells you what you need to know. The difference of 120mA is flowing into your 0V and that will contain the 1kHz.
I also have After Later Audio uBurst that has specs like +12V:120mA -12V:10mA, that is similar to the specs of Atom, but it's much much quieter, I would rather say that I can hear some little 1kHz noise only at super extreme level of amplification, which I would never hear normally. It is powered to the same board and doesn't make pickups to other modules. In opposite to this the whine of Atom is pretty audible at quiet moments in songs and in pauses when no other sounds are produced.

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Re: Background electric noise problem

Post by Graham Hinton » Sat Mar 07, 2020 8:03 am

anre wrote:
Sat Mar 07, 2020 3:08 am
I also have After Later Audio uBurst that has specs like +12V:120mA -12V:10mA, that is similar to the specs of Atom, but it's much much quieter, I would rather say that I can hear some little 1kHz noise only at super extreme level of amplification, which I would never hear normally. It is powered to the same board and doesn't make pickups to other modules. In opposite to this the whine of Atom is pretty audible at quiet moments in songs and in pauses when no other sounds are produced.
The large differences in currents is a warning that a module might be a problem, rather than confirmation that it is. The currents will be an average DC current plus an AC current dependent on what the module is actually doing. For example, modules with 7-segment LED displays often cause interference due to the displays being scanned at audio frequency and comparatively large currents being switched. The Atom is scanning knobs all the time. That could be solved by better design, but that won't happen any time soon or be retroactive. It wouldn't hurt to discuss this problems with the module maker.

You can waste a lot of time hunting down modules that cause such problems and modules that are sensitive to them and then you never know that it won't happen again if you decide to buy another module. You can't fix inherent module problems, only decide not to use them when that was the module you really liked. The common factor is the power distribution and that is what needs addressing. Getting power from a case maker is like getting brain surgery from a plumber. So what do you want, form or function?

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Re: Background electric noise problem

Post by anre » Wed Mar 11, 2020 4:06 am

This seems to be the case, thank you a lot Graham for your help in understanding my problem, your knowledge is precious for me.

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Re: Background electric noise problem

Post by Clank » Sat Mar 14, 2020 5:18 pm

Graham Hinton wrote:
Sat Mar 07, 2020 8:03 am
Getting power from a case maker is like getting brain surgery from a plumber. So what do you want, form or function?
This is so rude, you don't know each others, our products and our backgrounds.

If you're after large studio cases and linear power supply I do understand, for sure they are better on the paper, but we're talking of psus for small travel cases which has to be light and transportable so switching power is pretty the unique answer.I think our psus does a really great job since is the first time someone experience a noise problem which btw I'm pretty sure, like you said at the end, comes from the modules itself.
From what you wrote in this thread I doubt you had only passed 5 minutes to read the description or specs of our psu so I don't think I'll pass more than this time after you.
Helping people to resolve problems is really nice but please don't insult other work without first be sure of what are you speaking about.
Cheers.

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Re: Background electric noise problem

Post by Graham Hinton » Sat Mar 14, 2020 8:59 pm

Clank wrote:
Sat Mar 14, 2020 5:18 pm
If you're after large studio cases and linear power supply I do understand, for sure they are better on the paper, but we're talking of psus for small travel cases which has to be light and transportable so switching power is pretty the unique answer.
This is not about linear vers. switch mode. The fact that you think it is shows that you don't understand the problem.
It's about grounding and distribution.
like you said at the end, comes from the modules itself.
I didn't say that, I said "The common factor is the power distribution and that is what needs addressing."
From what you wrote in this thread I doubt you had only passed 5 minutes to read the description or specs of our psu so I don't think I'll pass more than this time after you.
You don't actually have a spec to read, just hype.
I don't need to see more than the dc jack and exposed switch on the outside of the case to know that it's not going to solve the problem and the pictures above confirm that. It's just another copy of an Americanised Eurorack case like have been causing similar problems for years, however nice the Rexine is.
Helping people to resolve problems is really nice but please don't insult other work without first be sure of what are you speaking about.
I know what I'm talking about.
As you are in Italy are you aware that this case needs CE certification to be legal to sell in the EU? I don't see any CE marks.

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Re: Background electric noise problem

Post by MindMachine » Sat Mar 14, 2020 11:31 pm

anre wrote:
Thu Feb 20, 2020 7:41 am

Image

The PSU I use is https://www.clank.eu/xpsu, and as far as I understand it's introduced as a safe, quiet and high quality power supply. P.S.: I am not trying to blame the PSU and its manufacturer. I'm quite a newbie, hopefully I do something wrong and there is a solution. Thanks.
That looks bunk. Worse than what I build for myself. Sorry that does not add to your conversation but I would run away and buy something else. It looks weak and homebrew.

Hinton is not going to pamper you but he will set you straight on the issues at hand. That looks suspect.
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Re: Background electric noise problem

Post by Clank » Sun Mar 15, 2020 12:05 pm

If you know how a DC jack works, you should also know that the uncovered PIN Is actually disconnected whenerer any dc jack is plugged in..the case Is grounded thru it's own brick converter as long as you buy a grounded one.
What else?

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Re: Background electric noise problem

Post by Pelsea » Sun Mar 15, 2020 12:50 pm

Perhaps he was referring to the uninsulated clips on the power switch?
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