Background electric noise problem

Anything modular synth related that is not format specific.

Moderators: lisa, luketeaford, Kent, Joe.

Post Reply
anre
Learning to Wiggle
Posts: 5
Joined: Fri Feb 14, 2020 10:42 am

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.


djs
Super Deluxe Wiggler
Posts: 1091
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

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

anre
Learning to Wiggle
Posts: 5
Joined: Fri Feb 14, 2020 10:42 am

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.



djs
Super Deluxe Wiggler
Posts: 1091
Joined: Wed Sep 01, 2010 8:36 am
Location: South Beloit, IL

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

loydb
Super Deluxe Wiggler
Posts: 1097
Joined: Sat Feb 13, 2010 6:45 pm
Location: Austin, USA

Re: Background electric noise problem

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

Watching...
15U 168hp Zebrawood case Build Log [FINISHED]: https://www.muffwiggler.com/forum/viewt ... p?t=134540
MFOS Ultimate Expand-o-tron Build Log: http://www.electro-music.com/forum/view ... 797#308797
MFOS Mini-Controller Build Log [FINISHED!]: http://www.electro-music.com/forum/view ... hp?t=42968

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3008
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

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.

anre
Learning to Wiggle
Posts: 5
Joined: Fri Feb 14, 2020 10:42 am

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.

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3008
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

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.

anre
Learning to Wiggle
Posts: 5
Joined: Fri Feb 14, 2020 10:42 am

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.

User avatar
Fog Door
Wiggling with Experience
Posts: 433
Joined: Sun Feb 24, 2019 1:04 pm
Location: Down, down, down the dark ladder

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.

User avatar
cptnal
Super Deluxe Wiggler
Posts: 3623
Joined: Wed Jun 14, 2017 2:48 am
Location: People's Republic of Scotland

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:

anre
Learning to Wiggle
Posts: 5
Joined: Fri Feb 14, 2020 10:42 am

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.

User avatar
Blairio
Super Deluxe Wiggler
Posts: 1692
Joined: Mon Oct 07, 2013 9:50 pm
Location: Glasgow, Scotland

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

User avatar
cptnal
Super Deluxe Wiggler
Posts: 3623
Joined: Wed Jun 14, 2017 2:48 am
Location: People's Republic of Scotland

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:

User avatar
Graham Hinton
Super Deluxe Wiggler
Posts: 3008
Joined: Fri Jul 02, 2010 6:28 pm
Location: England
Contact:

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.

Post Reply

Return to “Modular Synth General Discussion”