Grounding Buzz + (Possible) Hum in Home Studio

Discussion in 'Recording/Live Sound' started by MagnumSSS, Apr 24, 2016.

  1. MagnumSSS

    MagnumSSS Member

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    Hey everyone, first time posting in this particular forum so I hope it's the right place.

    I'm a guitarist and worked with a contractor to build my home studio last spring and I'm having some ground buzz and hum issues (I believe they're separate issues).
    • First, when I touch anything metal on my guitar (either humbuckers or single coils), the ground buzz goes away. Thus, I'm pretty sure that this is a grounding issue.
    • Second, my 80 watt boutique Fender Showman clone has a very obvious hum when I crank up the volume...but less obvious when the volume is donw. The hum changes in intensity when I change the pickup selector on my guitars. One has Harmonic Design Z90s, the other has Gibson PAF Humbuckers. The bridge pickup is about twice as close to the strings as the neck pickup, and it makes a more audible hum. Seems related. Obvious? LOL. My Super Reverb and Princeton Reverb do this as well. Is this normal? It very well may be and I just need to live with it.
    I took everything out of the equation by unplugging everything in the room (ductless mini split HVAC unit, iMac, monitors, audio interface, other amps, pedalboard, humidifier...everything). I then plugged straight into my amp with a single guitar cable and the amp was the only thing plugged into the wall in the entire room. I experience the two issues mentioned above. No other electrical device in the room could be contributing to the problem with this approach.

    My neighbor is my electrician so I have some good details about my room:
    • There's 5 completely separate circuits in the room:
      1. Lights (not using LEDs, but using a dimmer)
      2. ductless minisplit (HVAC)
      3. south wall outlets
      4. north wall outlets
      5. east wall outlets
    • The 15 amp circuits use 14 gauge wire and are isolated with #10 gauge ground wire (two sizes bigger than they really need to be...so this is good).
    • The grounds are isolated at a junction box (in between main electrical panel and the studio) before coming into the studio.
    • We measured the voltage current and it's 126.1 - 126.2 volts (steadily bouncing between those two numbers)
    I have a lot of detail about my room in this blog post: http://www.sixstringsoul.com/how-to-build-a-home-studio/.

    Here's two potential issues that I wanted to run by you all:
    • I have hat channel in the walls, decoupling the drywall from the studs via whisper clips. The room is 10x17 and there is a 2" metal hat channel rod attached horizontally along the studs, the entire length of each wall. They are vertically spaced two feet apart. So, I think there's 4 rods on each wall, the complete width of the wall. Also on the ceiling. That's a lot of metal in the walls. See my blog post for a picture. I'm essentially in a metal cage. There's two layers of drywall and a layer of green glue in between each layer of drywall. Could the hat channel be acting like an antenna and perhaps my amp, guitar pickups, and or speakers (which have huge magnets) are sucking some noise in from the hat channel in the walls?
    • I use a dimmer...and it does affect the nature of the noise (and gets slightly quieter when the light is off), but even with the lights circuit completely shut off...I still have the two issues mentioned at the top of this post.
    The only solutions, at this point, that I can think of, are products like these:
    Is this my best route to solve my two issues? Any other thoughts?

    Thanks,
    Dan
     
  2. pbmw

    pbmw Member

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    It's the dimmer
     
  3. ronzie

    ronzie Member

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    ^^^ Yup...

    How many phases do you have???

    AC and lights on the same phase.

    Audio on it's own phase.

    Then there's the load balance issue...
     
  4. MagnumSSS

    MagnumSSS Member

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    Thanks for the replies.

    We had the power turned off to all circuits (including the lights) except for the circuit with the outlet that I was using to test the amp. How could the dimmer be possibly be causing an issue if there was no power to the lights?

    About phases and load balance, I'm not sure what your exactly referring to. Mind offering a bit more detail? I'm no expert in electricity :)
     
  5. pbmw

    pbmw Member

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    The dimmer is basically a big L pad. Like a big wire wound resistor. It will induce a current 90 degrees out of phase. I'm not sure if it's wired so the coil portion of the dimmer is before the switch or not but I'll bet it's the dimmer.
    I went through the same thing in my studio before I just took it out and used low wattage bulbs in my lamps.
    Hope this sheds a little light ...:)
     
    buddaman71 likes this.
  6. MagnumSSS

    MagnumSSS Member

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    Thanks @pbmw ... can the dimmer contribute to EMF interference? I emailed Ebtech and they suggested this test:

    "When you here the Hum or buzz turn the volume knob on the guitar all the way down to see if it goes away. If it does it is EMF interference. This can be caused simply by the 120vac running in the conduit pipes in the wall or maybe fluorescent lighting in the room or a power transformer outside near the house or high tension power lines outside the house."

    I did that test, and the buzz and hum (both issues) go away. So, by his recommendation, my problem is EMF interference.

    Thoughts?
     
  7. ronzie

    ronzie Member

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    What I'm sensing here there are more problems than meets the eye. But don't sweat. It can be dealt with and there's only so much you can do without spending $$$.

    Your dedicated studio panel is pulled from the main panel that delivers to the rest of the house. If everything in the house isn't unplugged for the test, everything is suspect.
    It's neutral to ground current that's creating the hum and it's harmonics. Where is the dedicated panels isolated ground going? Is it floating or is attached/bonded to the main panel ground? Is it a home run directly to earth or tied to a cold water pipe? Where is the Main panel's ground going?

    Phases relate to the service the electric company gives you and your local codes. Single phase, two phase, three phase (etc) and it's based on residential V commercial.
    My guess is you have 2 phase to be able to create 220vac. In two phase, the raw panel is layed out so that every other breaker picks off a single phase. Counting down the panel starting on the left side breaker 1,3,5(etc) is one phase and 2,4,6 is the other phase. Those are separate taps from the electric company transformer on a pole or in the street. The other tap from the transformer is the neutral which is shared by the two phases to create the 120 vac referenced to ground.

    If you put a load on one phase, say washer and dryer, electric stove etc and run them, then put only a charging cell phone on the other phase you have a load imbalance with current delivery from the street transformer. That imbalance/stress shows up on the neutral to all circuits as ground current. Heat and noise. That just a simplistic illustration.

    I'm not saying you have a load imbalance problem, but I think it helps describe the issues that crop up.

    Th dimmer won't necessarily be a problem with the breaker off, provided it's functioning properly. I would guess you have a modern dimmer like a Lutron and those things are a Triac circuit and not a hum bucking autoformer/dimmer. They dump hash down the neutral because of their opposing diode design. When they go bad they can add nasty buzz to other circuits on it's phase even with the breaker off. You would have to pull the dimmer out off circuit to make the test. But I doubt it's bad. It's just talking to sensitive stuff (your audio) that's living on the same phase.

    126vac is a hair hot. It can screw with the power supply section of your amp and stress rectifier tubes and filter caps and put them over the edge. In turn it throws the bias of the amp off..

    Gotta go.
     
  8. maydaynyc

    maydaynyc Supporting Member

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    I have a similar problem in my studio. I even had the problem when I used a battery powered amp not hooked up to AC at all. From my research and various vendor opinions it seems that I have wires running across sprinkler pipes in the basement ceiling directly below my studio that is causing the problem. That would make sense because when I bring my guitar/battery powered amp down to the basement and hold the guitar up to the sprinkler pipes the noise gets louder the closer the pickups are to the pipe. But my problem is that there are tons of wires running through various conduit and over and under pipes (my studio is in an old retail strip mall building), some of which are not even in my premises but neighboring tenants. I would love to have someone come in to help diagnose and fix but the cheapest estimates I got were thousands of dollars just to come look with no guarantees they could fix it.

    I'm watching this thread with interest, I hope you find a good solution and that it can apply to my problem!
     
  9. MagnumSSS

    MagnumSSS Member

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    @ronzie - Thank you for your detail. Some feedback:
    • The dedicated panels isolated ground is going straight down into the earth. My electrician said it's a copper rod going 8 feet down into the ground. He also grounded our plumbing where the water main just comes into the house.
    • What are the solutions to a load imbalance, if one exists?
    • Yeah, I think it's a Lutron dimmer (just Googled it). You're suggesting that it's "talking" to my guitar equipment...even when it's completely off (no lights) or even further when the circuit is disconnected?
    • As for the 126 volt reading, in order to keep it at a steady 120v, would I have to get an isolation transformer such as http://www.amazon.com/Tripp-Lite-Isolation-Transformer-Outlet/dp/B00006HPFH
    @maydaynyc - Yeah it's frustrating and I think the problems are often so unique for everyone, that without expert advice like everyone chiming on this thread, we'd be up shiht creek!

    On a side note, the guy from Ebtech suggested this device: http://www.morleypedals.com/delc.html. He said that they do not have a device that will remove EMF interference that goes on the power plug, as the interference is coming from the front side of the amp. If he's right, then it has to be something like the dimmer, the phase of the wiring, the hat channel (metal cage) acting as an antenna, etc...right?

    Thanks, you all.
     
  10. jmoose

    jmoose Member

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    That sounds pretty normal to me... some buzz with electric guitars & amps is pretty typical. If things "shut up" a bit, or a lot a bit when you touch the metal parts of the guitar, say the strings & tuning machines then you're properly grounded there. If it got louder, or didn't change that'd usually be a fault in the guitar wiring.

    Likewise amps buzz, they make noise. Sky is blue dogs bark and Satan Claus, he's out there. If you unplugged & shut off everything else including the dimmer then chances are this is "normal" and yeah, you probably need to learn to live with it.

    If its the fault of a dimmer, even a cheap one... its going to introduce noise only when on and at an intermediate position. If its off, or full on it probably won't interject noise anywhere else. Single coil guitars are more prone to this sort of interference... spin around and "find Mecca" - aka the quiet spot.

    Noise on power comes across from one or two ways, its directly injected or its airborne. EMI/RFI. You can search for airborne noise with a battery powered AM radio, turn to a quiet weak spot on the dial and walk around holding it up to things... when you find the culprit its going to get louder.

    Another,newer form of noise... which usually plagues older buildings now is "PLC" or Power Line Communications.

    Stuff like automatic meter reading, broadband transmissions over AC power etc. Nasty stuff.

    https://en.wikipedia.org/wiki/Power-line_communication

    Given the descriptions it sounds like your place is properly wired with decent precautions. Power noise can be a nightmare and very costly to sort out, stumping even the best electricians because its like chasing a ghost. If in doubt bring your rig to a friends house or studio, is there an equal amount of noise there? Yes? Then you have nothing to worry about!
     
  11. MagnumSSS

    MagnumSSS Member

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    @jmoose - There must be no noise darnit! No noise! LOL

    I did the whole spin around approach when holding my guitar and sitting on my chair. With all circuits off except for the outlet that the guitar amp is plugged into, the only time the noise gets louder is when I spin and face my speakers. That's to be expected, however.

    Now, when the dimmer is on at about halfway or full up, that DOES create an additional slight boost in the buzz I'm hearing.

    And remember, this happens with both humbuckers and my Z90s (which are humbucker sized P90s, which are essentially single coils).

    Something's up, and I want to fix it. Any more advice?
     
  12. MagnumSSS

    MagnumSSS Member

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    One more thought, would adding a ground rod down through the concrete patio into the earth, from the sub-panel/junction box that is right outside my studio (all 5 circuits feed into this sub-panel/junction box from the main panel), be something worth doing? Perhaps that additional grounding would help?
     
    Last edited: Apr 25, 2016
  13. jmoose

    jmoose Member

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    Again this all sounds perfectly normal.

    Any standard dimmer between on, and off, is going to throw EMI/RFI trash into unbalanced signals and giant magnets, aka pickups.

    The only fix, given that everything else is in spec would be to rip out the $10 dimmers and replace them with proper variac dimmers. Not cheap, and you'll have to rip a large hole in the wall both for the physical space and additional framing to reinforce their weight.

    Otherwise ronize gave you a good punch list to work through with your electrician neighbor. Failing any of that drink more whiskey, it'll help with the buzzes...or drink less! All depending... YMMV etc.
     
  14. MagnumSSS

    MagnumSSS Member

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    I agree. The dimmer has to go. But even when the dimmer circuit is off (I mean completely cut out via the main panel...getting no power), I still have a (quieter) buzz issue...even with humbuckers. It goes away when I touch the strings, which I've now been reading that a lot of people say is normal. Still sucks.

    There is also a low level hum (60 cycle?). Both the hum and the buzz go away as I turn down my guitar volume knob.

    I'll talk through this with my electrician. Still feels like a crap shoot.

    Oh, and my lights dim slightly in the studio every once in a while. Maybe once or twice an hour? Could it be a load imbalance or something caused by some device/appliance running off another circuit in the house? Maybe the furnace kicking on?
     
  15. Motterpaul

    Motterpaul Tone is in the Ears

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    As Jmoose said - your guitar noise is simple RF (radio freq) hiss your pickups are picking up. Stand facing North and slowly rotate 360 degrees. If it changes you can be sure you are merely an antenna. The answer is better, shorter cables, humbucking pickups, or just living with the noise because you will never hear it when you are playing.

    The Dimmer is also a problem - you just can't have dimmers in studios. They put a hum on the line. If you must have dimmers use variacs to actually reduce voltage only on the lines the lights are on (it's overkill, but it works)

    Finally - have you actually put a metal pole into the earth someplace close to your junction box? This is where the actual "grounding" happens.
     
  16. MagnumSSS

    MagnumSSS Member

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    Thanks for chiming in @Motterpaul - Yeah I'm aware of the baseline hiss that is mostly unavoidable with guitar pickups, but it's more than what I'm used to. It doesn't change when I spin around on my chair (unless I face my speakers, which is obviously going to cause some feedback). I have great cables (Evidence Audio for the most part). Even the Les Paul with the Gibson PAF humbuckers has an extraordinary amount of hiss.

    The dimmer has to go. Totally agree. That will be one of my first moves.

    My main electrical panel on the outside wall of the house has a copper grounding rod going straight down into the ground. That should be good. However, the junction box on the outside wall of my studio (that is about 20 feet away from the main electrical panel), which has 5 circuit lines running through conduit to it, is NOT grounded with it's own dedicated copper grounding rod going down into the earth (through my concrete patio). The grounds for these 5 circuits are going through the conduit back to the main electrical panel...and (I assume) are connected to the main grounding rod going down to the earth from the main electrical panel. A friend recommended that I also ground this junction box with its own copper rod going down into the ground. I'm trying to get some clarity as to whether this will actually have an impact. Thoughts?
     
  17. ronzie

    ronzie Member

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    I checked your blog and your looking good!

    Please correct me if I'm wrong... It wouldn't be the first time.
    The big thing I noticed is the use of plastic outlets and Romex. Is this correct? Using "1900" boxes and Bx cable do one of 2 things; it either acts as a ground and shield in a non-isolated ground system and/or it acts as a shield in a isolated ground system (UG system). With the plastic stuff you get no shielding from EMF/RFI.

    Yes, you can use modern dimmers, but they should not change the buzz depending on the position of the slider. In a properly installed system, as in proper polarity on the hot and neutrals on all of the circuits, proper shielding on the runs and a grounding system to a singular point, they work without a hitch(until they burn out). They also cannot live on the same phase as the audio stuff. That's problem if your house is only single phase.

    The hat channel isn't an issue. It can't receive and transmit. It's a blind alley. If it was the channel, you'd connect all of the channel with a beefy wires then pull that to ground
    to the sub panels isolated ground bar.

    Pulling a "second ground" will do you no good. It appears you already have 2 grounds, hence the 60hz hum loop(and it's harmonics)you're hearing. The main panel and the sub panel need to be bonded at one point only. My best guess is the main house panel (box) itself is the main grounding point. Then the sub panels isolated ground bar should be bonded to the main panel box itself and the main panel goes to your grounding rod.

    Brown outs can occur for a few reasons. The electric co. transformer is on the edge and can't deliver the current, a breaker may be weakening(or not properly rated), the wiring at the box may not be screwed down tight (same with outlets). A start up motor (charging a cap) on an appliance could be hurt and needs to pull more juice than it's rated for etc....

    Way too many questions without being there to be of any help. But you have two main problems. A ground loop of some sort and EMF/RFI. The loop should be easy
    with some investigation. The noise attacking your pickups, not so easy. Get rid of the loop first.

    You can't have a load imbalance in a single phase system. Any word on how many phases you have???
     
  18. MagnumSSS

    MagnumSSS Member

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    Thanks, @ronzie :)

    Interesting point about the plastic outlets and Romex. It seems like the1900 boxes (which are metal) will help regardless of how the grounds are wired to/in my studio (either grounding or shielding). Since my electrician is going to isolate the grounds (in the junction box outside my studio wall...which is connected 20 feet away to the main panel), then it seems they will then provide shielding? I'm sure he can replace some or all of the outlets (maybe just the ones that I plan to plug my amps into?), but it sounds like a big job to rewire the whole room with Bx cable (?) instead of Romex and only "hope" that it helps. Thoughts there?

    Yes, the ground wires that feed into the studio circuitry head back to the junction box outside my studio wall, which then heads back (via conduit along my outside wall) back to the main panel 20 feet away.

    I'm going to have my electrician let me know about my phase setup. I've made notes to have him ensure that the studio lighting, studio HVAC (and appliances in the house) are all using circuits on a DIFFERENT phase than the studio outlets (which I plug music gear into).

    Does this help clarify or change anything? Any other thoughts? I'm trying to get my shortlist down for my electrician to address. Here it is so far:
    • Isolate the grounds
    • Replace the dimmer with a normal light switch
    • Replace the plastic outlet boxes with 1900 boxes (metal) - If possible, also replace Romex wire with Bx cable
    • Check how many phases that I have (Two?) - Ensure that the studio lighting, studio HVAC (and appliances in the house) are all using circuits on a DIFFERENT phase than the studio outlets (which I plug music gear into).
    Anything else I should add to this list?

    Thanks all!
     
  19. MagnumSSS

    MagnumSSS Member

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  20. football

    football Silver Supporting Member

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