Annoying speaker buzz when plugged on same mains as computers and gear

Discussion in 'GEAR Talk Forum' started by Fab, Jan 12, 2019.

  1. Fab

    Fab protect your ears!

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    Feb 18, 2016
    Hey there,

    I had this problem in my last place too, the solution was to have the powered speakers go through a 20m long extension lead and into a different wall socket than my main computers and gear.

    I think the problem had something to do with an electrical loop of sorts, the speakers do not make the buzzing sound in any case when they were not connected to the audio interface.

    If there are any secret electricians that have had this problem and can point me towards a cause + why a long extension lead fixes the problem, I'd be grateful to know.

    Thanks,

    At the moment my solution is to cry myself to sleep...

    ^ and also an extension lead :)

    Fab
     
  2. pderbidge

    pderbidge Senior Member

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    I could be wrong but I think even really good electricians will tell you that these kinds of issues are all trial an error. Power has a mind of it's own and noises, hums, hiss, etc.. will seem to develop anywhere it feels like it. I suppose the cleaner you can make your power through power conditioners etc... will help but still not a guarantee and also quite expensive. You just have to take it one at a time til you isolate the issue and then solve it.
    Here are some various troubleshooting tips I've found helpful over the years.
    1. Try a Surge protector or some type of power conditioner, preferably one with some audio noise filtering. Furman is pretty good at this.

    2. Check your cables. 90% of the time a badly made or failing cable is the culprit.

    3. Ground loop issues (usually that 60hz hum)-
    - Eliminate the ground from the outlet on each piece of equipment one at a time and if it goes away, consider a ground loop eliminator like this
    NOte: It's usually not a good idea to eliminate a ground permanently as it is there for protection which is why I recommended the Hum X as a solution once you found the ground problem. You could technically just keep the ground eliminated but then you run the risk of not keeping your equipment protected.
    - If the hum doesn't go away from eliminating the ground on a plug then start unplugging the 1/4 inch, XLR or RCA cables one at a time and if removing one removes the ground then try a filter on that cable.

    4. Computer noise: Sometimes the noise is coming from some interference in the computer.
    - Try a different USB cable to your audio interface.
    - Try a USB filter
    - Unplug the front audio jacks on your pc going to the motherboard. They can act as large antennas picking up any noise in the system and projecting it through the soundcard. This was an issue I recently had with a new computer build.

    I'm sure others will think of many more.
     
    Last edited: Jan 12, 2019
  3. wst3

    wst3 my office these days

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    I do not mean to sound critical or mean, but that could not be further from the truth. Electrical noise problems in studios are well understood, and easily (not always inexpensively) solved.

    Be very careful purchasing power conditioners, the vast majority are a step above snake oil. Among other things, avoid MOVs at all costs. Not only do they do little to suppress surges, but they can (will) fail, and there will be no indication thereof. They can also exacerbate noise problems.

    It certainly makes sense to check cables, but in my experience that has seldom been the root cause. Still, absolutely worth the time.

    NEVER ELIMINATE THE SAFETY GROUND!!!!!!!!!!

    This is reckless, and dangerous, and just a plain bad idea. Do not do it. If you need to troubleshoot use a transformer on audio lines. That will identify the problem. Hum-X is not good as a solution, but it can be handy as a troubleshooting tool.

    Now we are getting somewhere. The only way to diagnose the problem is systematic troubleshooting, and it sounds like you've taken most of the steps, but you didn't necesarilly document them so that they can help you.

    Very rare these days, but it can be identified easily enough through systematic troubleshooting.

    Here's the 5 cent version:
    • You need to identify the noise - is it power line frequency (hum) or radio frequency (buzz)?
    • You need to identify the aggressor (source of the noise) and the victim (how the noise is getting into the system).
    • You need to provide clean power and a clean, low impedance path to ground for every power source.
    • You need to provide a low impedance path to ground for every audio device.
    • You should avoid single-ended inputs at all costs.
    • You should check for poorly designed ("Pin 1 Problem") inputs.
    Your solution will become obvious somewhere along the line there. If this is all gibberish you might want to find a competent audio designer or technician to help (not do the work for you, use this as a chance to learn something new!).

    Solving electrical noise problems in a studio is neither rocket science nor voodoo. Please don't get sucked into either extreme.
     
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  4. dgburns

    dgburns splunge

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    I recently had a 20 amp service run from the main panel to my gear. It made a huge improvement, I have lowered the noise floor and it sounds great. Actually it sounds so much better, I’m a bit taken back. Only thing I can think of is the upgraded wire gauge and the isolation to the main panel.

    I used to use a balanced power unit, and just retired it.
     
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  5. wst3

    wst3 my office these days

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    Balanced power, or more accurately symmetrical power, is often a solution looking for a problem. It isn't snake oil, exactly, but it isn't the one-size-fits-all solution it claims to be. It addresses a very specific problem that is not present in most modern studios. On the other hand, it will eliminate noise from an old guitar amplifier like magic!

    If you have time, patience, and budget here is a recipe for an electrically quiet studio:
    1. Provide one (or more) dedicated power circuits, nothing with a motor or ballast should be on these circuits. If you want to get insanely cautious provide one circuit for analog power supplies and a separate one for switching supplies. Not worth the effort these days, but for those who want to take every possible step<G>!
    2. Use an isolation transformer to derive a sub-panel to feed the studio (this will mean something to your electrician even if it sounds like a foreign language to you)
    3. Use isolated ground outlets. As another extreme measure, run a separate ground wire from each outlet to the common for the studio.
    4. If you have any single-ended inputs convert them to balanced. You can use an active device (That Corp InGenius(tm)) or transformers.
    5. There is no need to balance the source. If you have a particularly troublesome source you can try "Impedance balancing", it can help the input stage reject noise.
    6. Check every input for the Pin 1 Problem, or assume they all have it and connect all shields to the chassis (probably the biggest bang for the buck).
    7. Use quality twisted pair cable to eliminate magnetic (60 Hz) hum pickup. Shielding is not required.
    8. If you have RFI (buzz vs hum) problems use a braided shield cable and ground it (to the chassis) at both ends.
    9. If you must disconnect a shield always do so at the source.
    10. Avoid (if possible) cable with foil shields and drain wires, they are susceptible to noise pickup.
    11. Insure that ALL wire is appropriately sized - meaning one size larger than required<G>.
    12. Use only quality connectors - they aren't cheap, but they are also less susceptible to noise pickup
    13. Keep different signal types and levels separated but at least six inches (not always easy!)
    14. Avoid wall warts and line lumps like the plague - which they are. If you have to use them place them as far away as possible from any audio circuit. Or replace them with a properly constructed power supply
    15. While patchbays are awfully handy (and they are) keep the number of patch points to a minimum. This is the exact opposite of conventional wisdom 20 years ago... the world is changing.
    There are probably other measures, but these are the ones that come to mind immediately, and these are the ones that have consistently worked for me.
     
  6. pderbidge

    pderbidge Senior Member

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    Okay? I'm not sure what you mean by "further from the truth" but I think someone experienced with electricity and audio could certainly get to the bottom of the issue quicker than others so I'll grant you that. I just don't know if everyone has access to someone like that and thus it becomes a matter of trial and error for the less experienced.

    I agree with this. All I'm saying is starting with the cleanest power is a step towards avoiding these issues in the first place but not a fail safe. What you determine as the method of getting to "clean power" is up to you and your own research. Lots of different products and opinions on this.


    I can see this being less of an issue in the studio so my experience has been with mainly live gigs in which case the root cause is quite often a bad cable, but in a studio where the cables don't get moved around a lot then yeah, I can see where perhaps it isn't as big of an issue.

    Um, I think I did said eliminating the ground is a bad idea long term but in order to test for an issue I don't see a problem with temporarily testing without a ground to diagnose if that is what is causing an issue. In over 30 years I have never once had an issue doing this and I've had to troubleshoot a lot of gear for live events. Of course carefully do so, but even plugging and unplugging gear with a ground you still have to be careful about it, but once you've found that a ground is a problem then the solution should be something that still keeps the equipment grounded and in tact like the product I linked to. I'm not touting that as a the best product for the solution. It's used more of a get by for the night solution in weekend warrior gigs but I'm sure there are better more robust long term solutions for the studio.

    I'm glad you agree, I guess?

    I agree and hopefully I didn't come across as saying such. All I said is it is a matter of trial and error, even for an experienced person. Thanks for dissecting my post for me though.
     
    Last edited: Jan 13, 2019
  7. wst3

    wst3 my office these days

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    Clearly you are one of the small group of people that could probably get away with troubleshooting by defeating the safety ground. But you do not know the skill set of the person you are talking to, or anyone else that might be listening. There are a handful of specific faults that would be instantly dangerous without a safety ground. Rare? Yes. Impossible? No. So I never suggest this as a troubleshooting step, and in fact it is probably the only bait to which I rise these days<G>!


    I certainly did not start out to dissect! I think we have different concepts of trial and error. To me it connotes someone trying this and that until they find a solution. To you perhaps it is more disciplined?

    What I do know is that there are a LOT of folks with experience and knowledge, they don't "try" anything, they make measurements and then they solve the problem. No trial required.

    Which is why I suggest that there are two solutions here:
    1) do it yourself, learn something, and then carry one. This applies to room acoustics, mixing, pretty much everything really, if you are curious then scratch that itch.
    2) hire someone who knows the ropes - it will save you a lot of time, and in many cases it can save you money, since you aren't purchasing things that don't solve the problem.

    Plus, it looks like I was a bit of a grump when I wrote that... sorry!
     
  8. pderbidge

    pderbidge Senior Member

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    Clearly I do not, however I'll be the first to admit that while I've had experience troubleshooting these situations in live events as a weekend warrior for many many years doing sound for customers and other times with friends that do this full time for pro audio companies, I do not consider myself a professional in this area and I am definitely not a professional when it comes to setting up studio equipment other than the gear I've set up in my own humble home studio. I am only relaying my experience but I do understand I may just be one of the lucky few and just havne't realized it yet. I am not completely ignorant to electricity as my grandfather was an electrician by trade and taught his children who has taught me a few things but that's not the same as someone who specializes in Studio and professional audio gear as it sounds like you may do. I wired my last home entirely by myself but once again that has nothing to do with troubleshooting a music studio. If your skill set is specific to this area then I am more than happy to defer to your advice on the matter. I don't need to be right for sake of argument and I'd rather be corrected than give out bad advice. After all I value the truth more than winning an internet argument.

    Yes, my definition of trial and error would be to first find out the possible causes of the specific problem and how to test for it and "then" test for it. After all you can't find the solution until you know the actual problem and verify what the problem is.

    This is the part I'm most curious about. How do they make their measurements? Are they using just a volt meter or are there other tools involved? (I'm a bit of tool collector so I'm always looking for an excuse for new tools:) )


    Don't worry about it. Tone is a very tricky thing to decipher through a blog so I wasn't trying to automatically assume you were being grumpy. I'm sure I must have seemed a bit grumpy myself.
     
  9. Nick Batzdorf

    Nick Batzdorf Moderator

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    Bill, what's the reason for separating the analog and switching power supplies? I've never heard that before, and it's intriguing.

    Also, you say to avoid MOVs - which means all garden-variety surge-protected power strips. How do they create problems?

    I have two isolation transformer boxes in my room. They work really well, effectively lifting the grounds for you - safely - while also filtering line noise. One of them is a Midi Motor Humbuster, from a company that's long gone, and the other one was given to me and has no brand name (must be custom-made).

    Are there any sources for similar boxes? They can't be outrageously expensive, at least compared to the ones you put by your breaker, because the only expensive parts are the gnarly 1:1 transformer, probably some big caps, and the 3U rack cases.
     
  10. Nick Batzdorf

    Nick Batzdorf Moderator

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    Bonus question: daisy-chaining circuit-protected power strips is bad because you can overload them.

    But I've heard that you can create a fault condition doing that. What's the mechanism?
     
  11. wst3

    wst3 my office these days

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    The most important tool is a screwdriver to disconnect things<G>! But it does help to have a good idea which direction to look.

    The most important tool in my bag is a "Pin 1" tester. This identifies devices that are susceptible to noise. Jensen posted an app note HERE that shows how to build one.

    I put this reading list together some time ago. I just checked, and as of right this second all the links are good<G>.

    Neil Muncy (sadly departed) is the man who coined the term, and in fact rediscovered the Pin 1 problem (the ancients are stealing our ideas!). Unfortunately I believe all his papers were published in the AES Journal, and you can't read them for free unless you are a member. Which is a shame, the man was a giant - he was a recording engineer, console and studio designer, Ampex tape deck guru, and all around nice guy. He recorded several segments for the AES Oral History project, all of which are on Youtube:
    Neil Muncy On Grounding
    Neil Muncy "Early Multitrack Recording"
    AES Oral History 004: Neil Muncy
    Neil Muncy "Early Studio Equipment Design"

    Phil Giddings has published a book and dozens of articles.
    A New and Important Audio Equipment Evaluation Criteria
    Technical Grounding Theory and Issues
    Power and Ground Update
    Shielding
    Implementing Electronic-Systems Wiring--Signal Cables
    A Perspective on Noise in Audio and Video Systems
    Implementing Building Electrical Wiring: AC and Ground
    Grounded Power Systems
    Equipment Wiring: Internal to Electronic Equipment

    Jim Brown is another leading light on the topic.
    Pin 1 Revisited
    Pin 1 Revisited Part 2
    Shield Current Induced Noise
    Shield Current Induced Noise Part 2
    Ham Radio Presentation (I do wish he'd edit this into a paper!)

    Rane Corporation used to publish technical notes at an alarming rate. Here are a couple I keep at my desk:
    Grounding and Shielding Audio Devices
    Sound System Interconnection

    Allen Burdick published A Clean Audio Installation Guide years ago, he has since retired, his document has not!

    Then there is Bill Whitlock - he has forgotten more about audio engineering than most of us will ever know. He has shared a few of his papers and presentations through the Jensen Transformer web site. Of particular interest are his papers on building a Pin-1 tester and his explanation of ground loops (spoiler alert, they are ever where and they are not evil!) You need to create an account on their web site to access the papers, which is unfortunate, but Bill is no longer the chief cook and bottle washer there (he is, quite deservedly, retired).

    Middle Atlantic is another web site that requires at least an email address, but their paper: "IntegratingElectronic Equipment and Power into Rack Enclosures" represents some of the best thinking on the subject.

    On the other side of the pond they do things a little differently. Tony Waldron is the British equivalent of Jim Brown I think. He has several papers as well:
    A Practical Interference Free Audio System (Part 1)
    A Practical Interference Free Audio System (Part 2)
    Bonding Cable Shields at Both Ends to Reduce Noise

    Of course if you want to go to the horse's mouth that would be Henry Ott. His books are the academic benchmark, he has a web site filled with papers and tech tips, well worth at least perusing.

    I know this is wandering off course a little bit, but this is good solid information, so if you are the curious type have at it!
     
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  12. pderbidge

    pderbidge Senior Member

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    Awesome! I'm going to bookmark these for future use. Thanks.
     
  13. TheSteven

    TheSteven Lunatic in training...

  14. Wolfie2112

    Wolfie2112 Senior Member

    This +1000. It's a great way to kill yourself.
     
  15. Wolfie2112

    Wolfie2112 Senior Member

    I had a "hum" in my studio recently, after several hours of trial and error, it turned out to be my old Mackie Big Knob.
     
  16. Nick Batzdorf

    Nick Batzdorf Moderator

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