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Please please help me with my electrical buzz problem!!

Discussion in 'Electronic Repair Modifications DIY' started by skinicod, Sep 17, 2012.

  1. skinicod

    skinicod Active Member

    Hello all,


    Not sure if this is the correct place to post this - but I am desperately trying to eliminate some electrical buzz in my studio. I have a room in a basement of a building and from between 9am to 6pm I have a strong hum coming through my speakers - and all transformers in the studio have the same kind of buzz coming out of them. I have not been able to establish what is causing the buzz, and I have very little control of what else is going on in the building.


    To that end I have tried the following to eliminate the problem:


    1) Unplugging everything and plugging them in one by one - nothing helped
    2) Having all equipment tested for faults - no problems
    3) I bought an Airlink balanced transformer 2000VA 230v to 230v CTE Three UK sockets (link here - Conditioning Balanced power supply: CBS2000: 2000VA 230v to 230v CTE Three UK sockets). Absolutely no change.
    4) Given number 2 and the fact that 3 didn't work, I tried removing the earth from the power source (I know this is very dangerous, but I was desperate to see if this would help) - no change.


    Does anyone have any suggestions as what might be the problem, or indeed a suggested solution.


    Any help would be amazing,


    Thanks guys,


    Paul.
     
  2. Boswell

    Boswell Moderator Distinguished Member

    Explain a bit more about the 9am - 6pm time frame. Is this the only time you are in the studio, or does the hum start abruptly at 9am and stop abruptly at 6pm?

    Is there a good ground connection available in your studio so you do not have to rely on mains ground?

    Do you get the same hum on headphones plugged into the phones output of your audio interface? If not, are your speakers powered monitors or are they passive driven by a power amp? Do you hear the hum when the powered monitors or power amps have no input cable plugged into them?

    Have you tried using a UPS (Uninterruptable Power Supply) of the type that does continuous synthesis?
     
  3. dvdhawk

    dvdhawk Well-Known Member

    You are in extremely capable hands with Sir Boswell, but if I may add a couple more questions that might help you narrow this down:


    What kind of things (outside of your control) happen in the rest of the building (or neighboring buildings)? Business / manufacturing - anything else that might use machinery, or be transmitting something, polluting the power, or radiating interference during business hours like clockwork?

    Is this hum like anything else you have heard before?

    Does it happen weekends and holidays when other businesses would be closed?

    Is the hum audible / visible in your recordings made 9am-6pm?
    Then is it present in the playback at 5pm still present after hours?

    Was there ever a time this problem didn't exist?
    If yes, what new equipment / cables have you added since then?



    Best of luck! We'll be watching for updates.
     
  4. skinicod

    skinicod Active Member

    Hey guys, thanks for the replies. I'll try and answer as best as I can:

    Basically around 6pm the hum disappears - I've said 9 am, but in truth I've never got in earlier than this! It is also mainly happens during the week - which is why I suspect it has something to do with the neighbouring businesses. That said as far as I am aware the other business in the building are on a different phase of electricity to me, though someone recently told me that this might not isolate them from causing the issue. To add further frustration, the hum does sometimes appear outside of these times.

    I have to rely on the mains ground - my thinking with getting the balanced power supply I mentioned in my first post, was to isolate the mains, as I believed (and this probably shows my very limited knowledge) that putting a transformer between my wall socket mains supply and the power supplied to the studio, would in effect isolate me from all mains problems. I have possibly purchased the wrong item, and a UPS might be better - and I did look for one here in the UK, but all the ones I found seemed to only supply direct mains electricity until such time as there was an issue, at which point they switched over to the battery.

    No audible hum is there on my headphones, but when recording through my microphone I do get some fundamental interference around 60hz and down. I think this may be due to the transformer on the mic itself, which is also plugged into the mains. I am going to try and record using a non powered mic to see if the issue still remains.

    My monitors are powered Adam A7's, and the buzz is coming through both when connected to an audio input, and when not.

    The buzz that comes through on these monitors is much higher than the 60hz down that I get on the recordings (possibly these are separate issues).

    In addition a lot of my wall warts have a similar acoustical buzz to the monitors.

    With regards to the building - it is an old church building that has been totally redeveloped inside - the church still use a main hall above my studio, to one side of me is are two shop, both of which operate normal retail hours (likely candidate for a cause of the issue - but unlikely i'm going to be able to get them to do anything to solve the issue!). Above the church hall are private flats. There is a lift (elevator) that goes up to the church and the flats, and behind my studio is a car park. The car park has various air conditioner units piped down from the flats in it, (though these come on and off all the time and don't seem to effect me). The car park also has an electric door (again this is constantly opening and shutting throughout the day and never causes a problem). In addition, there are water pumps which are on permanently to keep the basement of the church free from ground water.

    I share my electricity supply with the church.

    The buzz has only been there to my knowledge for the last 2 months, and I have not brought in any new equipment of cables in that time (bar the CBS2000 mentioned in my first post, which purchased to try and eliminate the problem).

    With regards to the sound of the buzz, it sound like a fly - though not as intense.

    Hope all that helps!

    Cheers,

    Paul.
     
  5. Boswell

    Boswell Moderator Distinguished Member

    Two significant points there.

    Firstly, what sort of transformer do you have on the microphone that is plugged into the mains? Is it an external power supply to give phantom power to the mic?

    Secondly, you get the buzz from the Adam A7 monitors when connected to an audio input, and when not.. Is the level of the buzz affected by the volume control (lower front panel) on the monitors both with a cable connected and with no cable?
     
  6. skinicod

    skinicod Active Member

    Hey Boswell,

    The mic is a SE z5600a tube mic, and the mains box powers the tube.

    The buzz does increase and decrease with the volume of the A7's both with and without audio cakes attached.

    Cheers,

    Paul.
     
  7. Boswell

    Boswell Moderator Distinguished Member

    You seem to be saying that the buzz is being generated by the Adam powered loudspeakers. Does this mean that if you record and mix some tracks to CD and then play the CD elsewhere on another hi-fi or studio system, there is no buzz audible?

    I like the concept of having audio cakes attached to your speakers. This is maybe where the ground currants are getting in.
     
  8. RemyRAD

    RemyRAD Well-Known Member

    Buzz and hum are two different types of problems. Hum generally indicates grounding issues. Buzz usually indicates improperly wired cables, electrical interference from heavy industrial items, improper wiring schemes. But if the speakers in and buy themselves, not connected to anything sit and buzz, is the input to those speakers shorted? If they're not shorted, all bets are off. Because if they're not shorted inputs, it's working like an antenna. If the inputs are shorted and the buzz continues through the speakers, there may be some fault in the speakers? Have you tried alternate sets of monitors and/or amplifiers? Switching power supplies that are used in many items today similar to that of computer power supplies I have found to be quite problematic when used for audio purposes. I personally prefer old-fashioned linear power supplies that include heavy Transformers because of the similar issues like you are having. This is not always possible with every piece of equipment. But it is possible to try and find and isolate where this is emanating from. Not every piece of equipment plays well with every other piece of equipment. Sometimes the best equipment assembled willy-nilly together can pose issues. Having the best stuff doesn't mean you're going to get the best stuff if one place presents an untenable amount of electrical interference and/or RFI. I was in an industrial park surrounded by high tech defense contractors such as General Dynamics, Lockheed Martin, Northrop Grumman, BA E. systems. And at random times day and night, cell phone service would be a abruptly interrupted. Since my recent move, this is no longer happening. I have surmised that many of these defense contractors are utilizing high level radar and other items that might be in testing procedures causing this? It could also be Dulles international Airport and my close proximity to their radar systems? But now I am actually closer to the Dulles airport radar systems that I was to the defense contractors and this problem is no longer happening. So sometimes it's location, location, location. Then your only course of action is to move.

    I may offer up one other suggestion. Try getting some chicken wire fencing and surround your equipment with the chicken wire fencing and grounding the chicken wire fencing. This is actually necessary for a client of mine (a prominent conductor here in the Washington DC area) because his stereo system/home entertainment system, had an incessant buzz, all of the time. The problem there was that he was around in very close proximity to the three high powered VHF TV stations and at least 12 FM radio station antenna towers. Every piece of equipment had this buzz in it. Putting chicken wire around his home entertainment equipment actually solved the problem. This same chicken wire completely surrounds studio A NBC-TV, DC. We never had any interference problems in studio A nor in our control rooms because of the heavy RFI shielding from the tower that was 1000 feet above us. You might be experiencing some kind of interference from a daytime directional AM radio station? When the sun goes down, they go off the air. RFI is a big problem, everywhere and especially here in this part of Washington DC where all the TV and radio stations are closely packed together within blocks of each other. And these are not AM stations but FM and television that also pose the same kind of buzzing RFI interference. There could be some kind of medical imaging equipment next door to you such as CT scanners, MRI scanners, x-ray machines, etc.. These are powerful devices that produce incredible waves of RFI. While your equipment may not be sensitive to their fundamental frequency, it doesn't eliminate harmonically related RFI. All wires, balanced or unbalanced, become full wave receiving antennas. Balanced circuitry usually prevents you hearing any buzz but at the same time, it is still modulating the balanced audio which causes its own type of intermodulation distortion superimposed on the otherwise quiet audio. So a lot of people have this condition without ever hearing it because they don't know what it's supposed to sound like without it. They may even wonder why their pristine high cost equipment doesn't sound as good as they heard somewhere else? And it's for reasons like those I mentioned. People misunderstand that common mode rejection only reject certain things. It doesn't reject everything.

    Your balanced power supply device does not necessarily provide electrical isolation. It provides balanced power. So perhaps a simple solitary AC mains power transformer may be a better solution as it provides actual electrical isolation and not balanced power. Those are two different things. And ya can actually use both of those together should you so desire because we do know that balanced power can offer up a lower noise level in your equipment. But you might need to isolate that power before going into the balanced power converter? And you currently have no way of isolating your power without a power isolation transformer. These Transformers in and buy themselves, depending on how many amps you need delivered can become quite costly. My 75 amp power isolation transformer cost me over $1000, twenty plus years ago and made all the difference in the world for me. Because it isolates my electrical feed from the AC mains. It also allows me to step up or step down the voltage with different available transformer taps. Quite handy. Quite necessary.

    104-240 V up or down on both sides of the transformer
    Mx. Remy Ann David
     
  9. dvdhawk

    dvdhawk Well-Known Member

    Is there any chance you could post a recording of the offending noise?
     
  10. DrGonz

    DrGonz Active Member

    As usual Remy hit the head of the nail very very well here. The very second I read that the buzz happened during the day and not so much at night made me think of AM radio signal interference. Isolation transformers are basically useless these days unless you open them up and remove the ground to make them truly isolated. Joining the balanced power w/ an isolation transformer sounds like an ingenious way to set up your power source in a studio. Yes it would be nice to hear a sample so all these great posters above can really tell a buzz from a hum...
     

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