I'm in deep and need help....

[G-Box]

Hi folks,

I've reached wits end with an electrical issue that is limiting my ability to get clean sound going in my studio. Over one year later, hundreds of hours of 'community service' by my local electrical contractors, over $100K spent by my local electrical company (Pacfic Gas & Electric) to clena transformer banks, wire them different ways, and finally removing all my neighbors from the transformer bank.... isolation transformers in my building.... and still I have a relentless 'ground' problem that foils my ability to get clean electric guitar sounds.

I would honestly document the entire process here, as I likely will be compiling something for my next wave of assistance I intend to seek, but as of right now I am waving my white 'surrender' flag, sending an SOS, asking if anyone knows an EXPERIENCED electrical troubleshooter, particular experienced with grounding issues (a bonus if they are experienced with solar power and inverters, as the building I am in has a tenant that used a solar backup system for their network and online business.)

The short end of the issue is that when I turn on a moderate to high level of gain on my electric guitar amps, I amplify what sounds like 60 cycle hum. Single coil and humbucking guitars are both prone to the sound. The kicker is, however, I can touch the metal portion of my guitar and make the problem go more or less away, even with humbucking guitars/Strats in hum cancelling mode. I have one guitar with substantially less hum (it's a strat with DiMarzio vintage 'noiseless' pickups with a lead-painted pickup cavity), which suggests the problem may be RF or EMF. However, there are certain mics that attract the problem as well, and the problem can go away completely with varying combinations of ground lifts, using direct boxes to reamp/absorb the buzz, snipping the connector on pin 1 in and XLR connector, etc etc etc. I have had an industrial isolation transformer custom built to clean up the power on the main panel of my studio, and the truth is the electrical was completely wired for the studio in mind -- there are no ground faults/receptacles that are visible, and the 'musical outlets' all feature 'home run' ground wires back to the panel (terminating in a bundled, or star ground), and no lighting/dimmers/ etc share the same phase of power as the musical outlets.

Ultimately, I'm fairly certain that the right candidate to help me solve this would need to come to my facility and attempt to mitigate this issue over the course of a week or so -- it has baffled some truly gifted EE's, but unfortunately none of the troubleshooters I've had can hear the nature of the problem conclusively (they're not studio rats/musicians themselves), so I am desperately seeking someone who operates in this capacity regularly and can offer some guidance/troubleshooting.

Please please PLEASE call/contact me if you have anybody in mind -- I am at wits end and my already stressed pocketbook can not harbor the problems much longer..............

THANK YOU EVERYONE.

[Soundman2020]

Hey Andy, welcome!

I'm not a huge expert on this, but I've gone through my fair share of tracking down similar grounding issues at video post facilities, which I used to design and install for a living, so I do understand where you are coming from, and how immensely frustrating this can be. I'd almost rather have a root-canal job done without anesthetic than try to track down some kinds of hum!

Some suggestions that might (or might not) help:

Your experts have probably already tried these, but it might be worth going over them again.

First, have you actually checked to see what kind of grounding problem you have? You say your system is star-grounded, in which case you should have no potential difference between the ground pins on all of your plugs. But have you checked? Have you actually gone around all your plugs with a good voltmeter, and measured the voltage on all of the ground pins? If you have ANY pair of plugs that show a difference of more than about 50 mv, then you have a good hint as to where your problem is coming from.

But don't just measure voltage: also measure resistance between the ground pins on all plugs. Under no-load conditions you might not see any voltage but still have a problem. so measure the actual ground resistance. It should be really, really close to zero ohms. You should only see the inherent resistance of the grounding conductor, and not a single fraction of an ohm more than that.

If that all checks out OK, then how about your neutral to ground bridge? Depending on where you live in the world, and what your local electrical code says, your neutral and ground conductors should be bridged together in the distribution panel, or at the closest transformer, and therefore they should be at exactly the same voltage. So if you measure the voltage between ground and neutral at any socket, it should be less than 100 mv (don't try measuring resistance here, if the power is turned on!). Anything over 100 mv is a red flag.

OK, so if all of the above is in line, how about your ground grid itself? Did you check that the central point for your star grounding really is well grounded? A single copper rod stuck into the ground a couple of inches won't cut it. You should have a proper grid, consisting of several rods buried down several feet underground, in a square pattern several feet across, and joined together with thick copper conductors. That grid is, in turn, connected at only one point to the central hub of your star ground system.

So you have all of that in place? Now its time to strip down your system to the minimal possible expression, and start working your way out from there. Unplug EVERYTHING in your entire studio. If it uses electricity and is part of the building (inside or out), turn it off and physically disconnect the plug from the socket. Computers, coffee pots, copiers, telephone exchange, servers, heaters, air conditioners, printers, radios, TVs, lamps, etc. Everything. Turn of all the lights, too. Use a battery operated lamp for light, if you have to. Have NOTHING AT ALL on in the entire building. Now plug in ONLY your amp and guitar. Nothing else. Everything in the entire building is DEAD except for your amp and guitar. Do you still have a hum problem? If so, then the problem is either in your amp, or it is in your guitar, or it is in the cable, or you have some major external EMF source really close to your building. There are no other choices. Any cell phone towers nearby? Heavy industry nearby? High tension power lines nearby? Radio / TV transmitters nearby? Etc. If you are dead certain that your amp, guitar and cable are perfect, then those are the only remaining possibilities. There is a solution for dealing with that to, but it's a biggie: Faraday cage. Hopefully, you do NOT need to go there...

Assuming you now have a clean setup with no hum. This is good news! You have a clean starting point! Now is is time to expand the system, bit by bit, one thing at a time, until you get the first hint of hum. Deal with that, then move on to the next one, turning on and connecting one thing at a time, and dealing with each of them in turn.

You most likely have more than one problem, especially considering that multiple people have played around with multiple things over time, so you really will need to go over the entire studio, one cable at a time, one piece of equipment at a time, testing everything and putting it all back in order. You say that you have tried multiple combinations of lifted grounds, snipped grounds, isolation transformers, etc., so all of those are now potential sources of problems, and all will need to be fixed. All cables, plugs, ground lifts, etc. will need to be checked physically and with a meter, to make certain they are set correctly. All of your racks, and each item in each rack will have to be checked, one by one, to fix whatever has been broken by well-intentioned but possibly misguided folks, trying their best but actually making things worse.

Depending on the size of your studio, it might well take more than a week to do this.

Unfortunately, in the worst case, you might now have so many problems that only a drastic solution will fix them all. In a couple of similar cases, we had to rip out everything and re-wire it entirely (both power and signal), since it was quicker and cheaper to do that than to pay experienced technicians for days of work, tracing one single faulty cable through a complicated run all over the building. On the two cases that I can think of where I had to do that for customers, it did work in the end, but boy did it cost them! Shutting down your entire facility for a month is a major big deal, and re-wiring it is an even BIGGER deal ( ) but if this is really important to you, it might be the only way to get it done right, once and for all.

But hopefully it wont actually come to that, and you'll find the culprits early on, with the procedure I outlined! It's better to give you the really bleak picture up front, then you discover a pleasant surprise after only two or three days of fiddling, than to expect to have it fixed in a jiffy but then spend weeks (and big bucks) without any results...

All I can say is: Good luck! You really will need it. Solving hum issues like this can be a huge PITA, (and a huge PITW).


- Stuart -

[G-Box]

Wow, Stuart, I can't thank you enough. Having chased this issue for the better part of a year, it has become increasingly frustrating and obviously very impactful on my business. I took a large enough risk making a leap and expanding my 10 year old studio business in a small market during a weak economy, but to emerge on the other side of this expansion with a ground problem of sorts has literally taken all I have to stomach through, both mentally and financially. It has only been on the grace and generosity of several local contractors and engineers that I have had the luck to perservere. With my helpers' interest waning, and the future of my studio seemingly in the wings, to have my call for assistance last night answered so thoroughly and so quickly means more to me than you could possibly understand.

The studio is located in Santa Cruz -- central California, about one hour south of San Francisco, about one mile from the Monterey Bay coastline. PG&E, our local electrical/gas utility company has been engaged in the troubleshooting of my issues since our first tests proved that something out-of-the-ordinary was occurring. The short end of it is that they deemed it feasible to completely separate my building's main power distribution panel from any neighboring buildings in this semi-industrial neighborhood. As it stands, between my studio, which is using roughly 30 amps of power at a maximum at any given time, and the neighboring CAD software development company in my building (which likely uses a similar draw at peak), there really isn't much power being drawn at any one time from the transformer bank located at the base of our driveway (which is suspended up high on a utility pole.)


So your time and energy are not in vain, I will follow up in the next couple of evenings when I have more time with a thorough floor plan and a bit more detail of the tests we have performed. I am quite certain that most of the points you have addressed have been checked and re-checked, but some of the issues you have brought to my attention underscore the importance of speaking directly with an electrical contractor who has an appreciation/understanding of the type of critical needs of a recording studio facility. If a day or two are all that are needed to strip down each receptacle, outlet by outlet, checking resistance and voltage, etc, it is time well-spent now, if only to re-document the troubleshooting steps so we can proceed with clarity.

You have literally thrown me a lifeline, if only emotionally, to perservere. I will remain in touch for the benefit of everyone here that may at some point be needing the assistance of the hell I've been going through.

Thanks once again- and particularly, thank you to John Sayers' and team for providing this forum for such helpful processes to exist.

Best,