I just spend a coupla grand on the best studio monitors, signal processors and monster cables. I just finished connecting everything and, yay! I just met the studiofile's worst enemy. You spend the extra money getting the best cables and monitors only to have to deal with ground loop.

I isolated the problem to my dbx 266xl compressor.

It seems that there are two solutions:
This: http://www.sweetwater.com/store/detail/CleanBoxII/ for $35.
What this does is break the ground in the audio cables.

And this: http://www.sweetwater.com/store/detail/HumX/ for $70.
What this does is safely remove the ground from the electric signal.

Does anyone have experience? Is there any other solutions?

It would also work - and be much cheaper - to use a 3 - 2 prong electric adapter - http://www.adorama.com/ZZAC32.html for $1.50, but all the article's I read on ground loop say this is dangerous and can cause electrocution. Is this really the case? I've never heard of someone being electrocuted because of one of those... and we're only talking about a signal compressor - not a refrigerator. (As you can tell I'm trying to get out of spending another $35 - 70 -- but not if its trully dangerous.)

Thanks in advance,
Chony

Chony,

Hook up the inexpensive ground defeater, then using a volt-meter measure the potential difference between the ungrounded device and other devices used in the operation. If the measured voltage is less than a few volts, both AC and DC, you should not have a safety problem using the ground defeater. However, if the reading is 12 volts or higher, AC or DC, there is a potential for electric shock.

Good Luck,

Gary

I stand to be corrected here, but my understanding is that when different equipment is connected together they are all earthed through the first piece of equipment. So the problem of looping occurred because there are too many pieces of equipment each of them earthed.
The solution is disconnect each piece of equipment in turn until the problem is solved.
Everything should be safe because as stated above each part is earthed through the previous piece of equipment it is connected to.
Start by disconnecting each piece from the end of the chain.

[This message has been edited by Graham UK (edited 03-10-2005).]

Chony,
In case you have more as one power circuit in your studio, just unplug the dbx from the circuit where all the other devices are and take the power from another circuit.

Mots likely the problem is gone.
(IF the dbx is the problem)

(You could test ofcourse by getting power from your kitchen or another place )

Dear Chony;

I am curious as to what your " best " monitors that you just purchased are?


Regards;
BN

Thank you everyone for your replies:

Gary - what you say sounds like the best idea, as I did try using a two prong just to test, and it eliminated 80% of the hum. If I only knew what a volt meter is. I'll have to ask my friends - hopefuly somone has one.

Graham - I've isolated the offending machine - its my dbx compressor. But I don't understand what you mean by "disconnecting" the equipment. If its disconnected, it can't be used - which is not exactly a solution. Additionally, every machine needs its own grounding as they are only connected via audio cables - which do not pass on the ground.

Fred - thanks for the idea. If I'm desperate I'll do this. I'd rather not have extention cords running through my hallway!

BN - Event Precision 8s. Originally I was thinking of spending $300 on monitors, but I wasn't satisfied until I heard these. I closed my eyes, swallowed, and laid the money down, and try not to remember that I ever had it. I have learned so much about sound just by listening to these beauties. http://www.zzounds.com/item--EVEASP8

Anyone with more ideas - please let me know!

It is common pracice in pro studios to link all the earths together and ground through one earthing point (usually the desk)to remove earth hum problems and also to ensure that every unit is earthed correctly - by disconnecting each piece of equipment, or as you have done in your case with the dbx, you have isolated the problem - you may also find that a lot of signal to noise ratio can be minimalised by running every piece of equipment at +4db, i.e that every lead has an earth (balanced cable) rather than being simply 2core or monojack (unbalanced), running as a 3core wiring system greatly improves the electrical performance for not much bigger cost although if you're soldering the plugs yourself it can be a real pain. Also, there used to be a problem with certain equipment that was wired for live, which involved swapping the functions of pins 2 and 3 (I think) in 3 core cable so this could also be a problem. Hope this helps

chony. I perhaps did not make myself very clear...when I say disconnect...I mean disconnect the earth from the mains plug on certain pieces of equipment.
audio cable connections have an earth as well as the signal so also carry earth from one piece of equipment to another. Plus if you have the mains earth connected on all the pieces just count up all the earth connections you can have....this can cause earth looping.

It has been my experience that most ground loops are the result of poor quality power supplies, many of which now come in the form of external supplies, also known as "Wall Warts." Instead of a pure DC signal emitted from the power supply, there is often a considerable component of AC ripple. This is because most power supplies no longer us AC filter chokes, which eliminated the problem of AC ripple in a DC circuit.

Additonally, some of the components we now use have differing ground systems. Not all equipment utilizes a negative ground throughout the system. Some have floating grounds, which cause their own set of headaches when it comes to 60hz humm.

Fortunately, most are low voltage systems, therefore, some of these problems can be eliminated, or at least reduced by the use of ground defeater adapter plugs. I have always been a stickler for properly grounding all electrical and electronic devices, however, I encontered a similar problem with my laptop computer's power supply. It was poorly designed, and the 60hz humm it produced when hooked up to my keyboard, amp, and other allied equipment was horendous. By unplugging each device until the humm dissapeared I was able to isolate the offending gear, the laptop computer. A $1.25 ground defeater solved the problem, and after measuring the electrical potential between the laptop and all other pieces of equipment, there was no electrical potential, therefore no concern for electrical shock hazard.

Good luck, and I hope you are able to isolate the remaining hummm or interference as well.

Gary

Choney, any luck with fixing the ground loop problem? I am experiencing the same issues. Please let me know if you've tried one of those Hum-X products, I would be interested in the results.

Thanks!